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acrac_69401_2
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Acute Nonspecific Chest Pain Low Probability of Coronary Artery Disease PCAs
|
SPECT or SPECT/CT MPI Rest and Stress Although stress single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) has comparable utility to stress echocardiography for the overall detection of ischemia in the emergency room setting [25], there is no relevant literature supporting its use in the setting of acute nonspecific chest pain with low probability of CAD. US Echocardiography Transthoracic Resting Resting transthoracic echocardiography is of utility to document anatomic abnormalities that may be the cause of nonischemic cardiac pains in the acute setting, such as diseases of the myocardium or pericardium or cardiac masses, to improve diagnostic accuracy and efficiency [22]. Resting transthoracic echocardiography has the ability to characterize wall contractile function, and because of its ability to be deployed at the bedside, this consensus report by the European Association of Cardiovascular Imaging and the Acute Cardiovascular Care Association supports its use to triage patients with acute chest pain [22]. US Echocardiography Transesophageal Transesophageal echocardiography is typically reserved for instances when nonischemic causes of acute chest pain, such as thoracic dissection, are under clinical consideration. It may be used as a follow-up to a nondiagnostic transthoracic study but is sometimes chosen initially when transthoracic echocardiography is anticipated to be nondiagnostic, such as related to patient body habitus or inability to comply with breathing instructions [22]. There is no relevant literature supporting its use in the setting of acute nonspecific chest pain with low probability of CAD. Acute Nonspecific Chest Pain There is no relevant literature to support the use of CTA chest with intravenous (IV) contrast in the evaluation of acute nonspecific chest pain of suspected cardiac etiology as an initial imaging test.
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Acute Nonspecific Chest Pain Low Probability of Coronary Artery Disease PCAs. SPECT or SPECT/CT MPI Rest and Stress Although stress single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) has comparable utility to stress echocardiography for the overall detection of ischemia in the emergency room setting [25], there is no relevant literature supporting its use in the setting of acute nonspecific chest pain with low probability of CAD. US Echocardiography Transthoracic Resting Resting transthoracic echocardiography is of utility to document anatomic abnormalities that may be the cause of nonischemic cardiac pains in the acute setting, such as diseases of the myocardium or pericardium or cardiac masses, to improve diagnostic accuracy and efficiency [22]. Resting transthoracic echocardiography has the ability to characterize wall contractile function, and because of its ability to be deployed at the bedside, this consensus report by the European Association of Cardiovascular Imaging and the Acute Cardiovascular Care Association supports its use to triage patients with acute chest pain [22]. US Echocardiography Transesophageal Transesophageal echocardiography is typically reserved for instances when nonischemic causes of acute chest pain, such as thoracic dissection, are under clinical consideration. It may be used as a follow-up to a nondiagnostic transthoracic study but is sometimes chosen initially when transthoracic echocardiography is anticipated to be nondiagnostic, such as related to patient body habitus or inability to comply with breathing instructions [22]. There is no relevant literature supporting its use in the setting of acute nonspecific chest pain with low probability of CAD. Acute Nonspecific Chest Pain There is no relevant literature to support the use of CTA chest with intravenous (IV) contrast in the evaluation of acute nonspecific chest pain of suspected cardiac etiology as an initial imaging test.
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69401
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acrac_69401_3
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Acute Nonspecific Chest Pain Low Probability of Coronary Artery Disease PCAs
|
V/Q Scan Lung Tc-99m ventilation-perfusion (V/Q) lung scan may be performed to detect a pulmonary embolism. There is no relevant literature to support the use of V/Q scanning in the evaluation of acute nonspecific chest pain of a cardiac etiology as an initial imaging test. Alternatively, evaluating CCTA versus stress MPI, a randomized controlled single-center study of 400 patients, validated against invasive angiography, documented a comparable length of stay (CCTA 28.9 hours versus MPI 30.1 hours) as well as no differences in major cardiovascular events at 40 months [28]. Another randomized controlled study comparing CCTA with SPECT MPI in 598 participants with low to intermediate risk documented time to diagnosis (CCTA 8.1 hours versus MPI 9.4 hours) and length of stay (CCTA 19.7 hours versus MPI 23.5 hours) (both P = . 002) [29]. The CATCH (CArdiac cT in the treatment of acute CHest pain) trial examined long- term outcomes of CCTA versus standard care in the setting of low-risk acute chest pains in a randomized cohort of 600 participants, with the outcome being MACE at 19 months. Overall occurrence of a primary endpoint was CCTA (n = 16) versus standard care (n = 47) (P = . 04) [30]. A meta-analysis of 37 trials (involving 7,800 patients), compared CCTA, stress echocardiography, and MPI SPECT validated against invasive angiography, or late MACE, in the acute chest pain setting. Weighted mean sensitivity, specificity, positive predictive value, negative predictive value, and total diagnostic accuracy were as follows: CCTA 95%, 99%, 84%, 100%, 99%, respectively; stress echocardiography 84%, 94%, 73%, 96%, 96%, respectively; and SPECT 85%, 86%, 57%, 95%, 88%, respectively. The investigators concluded there was no difference in negative predictive value but that CCTA had superior performance over stress echocardiography and MPI for the other indexes [31].
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Acute Nonspecific Chest Pain Low Probability of Coronary Artery Disease PCAs. V/Q Scan Lung Tc-99m ventilation-perfusion (V/Q) lung scan may be performed to detect a pulmonary embolism. There is no relevant literature to support the use of V/Q scanning in the evaluation of acute nonspecific chest pain of a cardiac etiology as an initial imaging test. Alternatively, evaluating CCTA versus stress MPI, a randomized controlled single-center study of 400 patients, validated against invasive angiography, documented a comparable length of stay (CCTA 28.9 hours versus MPI 30.1 hours) as well as no differences in major cardiovascular events at 40 months [28]. Another randomized controlled study comparing CCTA with SPECT MPI in 598 participants with low to intermediate risk documented time to diagnosis (CCTA 8.1 hours versus MPI 9.4 hours) and length of stay (CCTA 19.7 hours versus MPI 23.5 hours) (both P = . 002) [29]. The CATCH (CArdiac cT in the treatment of acute CHest pain) trial examined long- term outcomes of CCTA versus standard care in the setting of low-risk acute chest pains in a randomized cohort of 600 participants, with the outcome being MACE at 19 months. Overall occurrence of a primary endpoint was CCTA (n = 16) versus standard care (n = 47) (P = . 04) [30]. A meta-analysis of 37 trials (involving 7,800 patients), compared CCTA, stress echocardiography, and MPI SPECT validated against invasive angiography, or late MACE, in the acute chest pain setting. Weighted mean sensitivity, specificity, positive predictive value, negative predictive value, and total diagnostic accuracy were as follows: CCTA 95%, 99%, 84%, 100%, 99%, respectively; stress echocardiography 84%, 94%, 73%, 96%, 96%, respectively; and SPECT 85%, 86%, 57%, 95%, 88%, respectively. The investigators concluded there was no difference in negative predictive value but that CCTA had superior performance over stress echocardiography and MPI for the other indexes [31].
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69401
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acrac_69401_4
|
Acute Nonspecific Chest Pain Low Probability of Coronary Artery Disease PCAs
|
A meta-analysis of randomized controlled trials evaluating CCTA versus usual care for triaging patients in the emergency room setting documented efficiencies of CCTA for discharge disposition but increased downstream invasive coronary angiography and revascularization [32]. Hemodynamic assessment using flow indexes, derived from biophysical modeling of CTA-derived data, is a recent development. A small, single-center study was validated in animals (with CT-documented flow correlated with microsphere-determined flow; R-squared = 0.90, P < . 001) and also explored in 39 human participants with acute chest pain and normal coronaries, documenting excellent interobserver correlation (R = 0.96, P < . 0001) and agreement [33]. Although a report on the initial 1,000 participants in the international, multicenter, prospective, real-world registry, ADVANCE (Assessing Diagnostic Value of Non-invasive FFRCT in Coronary Care), has documented that CTA stenosis severity had an increased likelihood of an abnormal fractional flow reserve-CT, the utility of this measure was limited in practice, given that mild lesions could result in ischemia whereas intermediate to severe lesions could be nonflow limiting [34]. In addition, in common with the preponderant focus of other leading existing clinical trials exploring the utility of fractional flow reserve-CT, these studies were evaluated in stable chest pain cohorts, as opposed to the acute chest pain setting of the present discussion. Alternate approaches use concurrent CT perfusion (CTP) assessment to augment the anatomic data with functional characterization. In a subanalysis of 183 ROMICAT I (Rule Out Myocardial Infarction by Computer Assisted Tomography) participants, rest CTP predicted ACS independently of obstructive anatomic assessment, and sensitivity for detection of Acute Nonspecific Chest Pain
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Acute Nonspecific Chest Pain Low Probability of Coronary Artery Disease PCAs. A meta-analysis of randomized controlled trials evaluating CCTA versus usual care for triaging patients in the emergency room setting documented efficiencies of CCTA for discharge disposition but increased downstream invasive coronary angiography and revascularization [32]. Hemodynamic assessment using flow indexes, derived from biophysical modeling of CTA-derived data, is a recent development. A small, single-center study was validated in animals (with CT-documented flow correlated with microsphere-determined flow; R-squared = 0.90, P < . 001) and also explored in 39 human participants with acute chest pain and normal coronaries, documenting excellent interobserver correlation (R = 0.96, P < . 0001) and agreement [33]. Although a report on the initial 1,000 participants in the international, multicenter, prospective, real-world registry, ADVANCE (Assessing Diagnostic Value of Non-invasive FFRCT in Coronary Care), has documented that CTA stenosis severity had an increased likelihood of an abnormal fractional flow reserve-CT, the utility of this measure was limited in practice, given that mild lesions could result in ischemia whereas intermediate to severe lesions could be nonflow limiting [34]. In addition, in common with the preponderant focus of other leading existing clinical trials exploring the utility of fractional flow reserve-CT, these studies were evaluated in stable chest pain cohorts, as opposed to the acute chest pain setting of the present discussion. Alternate approaches use concurrent CT perfusion (CTP) assessment to augment the anatomic data with functional characterization. In a subanalysis of 183 ROMICAT I (Rule Out Myocardial Infarction by Computer Assisted Tomography) participants, rest CTP predicted ACS independently of obstructive anatomic assessment, and sensitivity for detection of Acute Nonspecific Chest Pain
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69401
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acrac_69401_5
|
Acute Nonspecific Chest Pain Low Probability of Coronary Artery Disease PCAs
|
One specialized protocol of coronary CTA is the triple rule out examination, which uses a specific contrast acquisition scanning protocol to enable assessment of the pulmonary arteries, the aorta and the coronary arteries [37]. For the purpose of this document, the triple rule out is considered part of the CTA coronary arteries. CT Chest Without IV Contrast Noncontrast chest CT can assess for the presence of a pericardial effusion, epipericardial fat necrosis, and other noncardiac causes of chest pain. There is no relevant literature to support the use of CT chest without IV contrast in the evaluation of acute nonspecific chest pain with low probability of CAD as an initial imaging test. CT Chest With IV Contrast Noncontrast chest CT can assess for the presence of a pericarditis, epipericardial fat necrosis, and other noncardiac causes of chest pain. There is no relevant literature to support the use of CT chest with IV contrast in the evaluation of acute nonspecific chest pain with low probability of CAD as an initial imaging test. CT Chest Without and With IV Contrast Chest CT without and with IV contrast as a follow-up to a suspicious finding suggested by radiographs of the chest is typically not used [20,38]. There is no relevant literature to support the use of CT chest without and with IV contrast in the initial imaging evaluation of acute nonspecific chest pain with low probability of CAD. CT Heart Function and Morphology With IV Contrast In a single-center retrospective analysis of 225 patients, heart morphology and function indexes, as a derivative of a CCTA study, have been shown to correlate with MACE at 13 months [39]. There is no relevant literature to support use of this test as an initial imaging strategy. See the CTA coronary arteries section above for coronary artery assessment.
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Acute Nonspecific Chest Pain Low Probability of Coronary Artery Disease PCAs. One specialized protocol of coronary CTA is the triple rule out examination, which uses a specific contrast acquisition scanning protocol to enable assessment of the pulmonary arteries, the aorta and the coronary arteries [37]. For the purpose of this document, the triple rule out is considered part of the CTA coronary arteries. CT Chest Without IV Contrast Noncontrast chest CT can assess for the presence of a pericardial effusion, epipericardial fat necrosis, and other noncardiac causes of chest pain. There is no relevant literature to support the use of CT chest without IV contrast in the evaluation of acute nonspecific chest pain with low probability of CAD as an initial imaging test. CT Chest With IV Contrast Noncontrast chest CT can assess for the presence of a pericarditis, epipericardial fat necrosis, and other noncardiac causes of chest pain. There is no relevant literature to support the use of CT chest with IV contrast in the evaluation of acute nonspecific chest pain with low probability of CAD as an initial imaging test. CT Chest Without and With IV Contrast Chest CT without and with IV contrast as a follow-up to a suspicious finding suggested by radiographs of the chest is typically not used [20,38]. There is no relevant literature to support the use of CT chest without and with IV contrast in the initial imaging evaluation of acute nonspecific chest pain with low probability of CAD. CT Heart Function and Morphology With IV Contrast In a single-center retrospective analysis of 225 patients, heart morphology and function indexes, as a derivative of a CCTA study, have been shown to correlate with MACE at 13 months [39]. There is no relevant literature to support use of this test as an initial imaging strategy. See the CTA coronary arteries section above for coronary artery assessment.
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69401
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acrac_69401_6
|
Acute Nonspecific Chest Pain Low Probability of Coronary Artery Disease PCAs
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MRA Chest Without and With IV Contrast MR angiography (MRA) has potential uses in the nonischemic setting if acute thoracic aorta conditions, including dissection or intramural hematoma, or aneurysm or pulmonary embolism are being considered [40]. There is no relevant literature to support the use of MRA chest without and with IV contrast for the evaluation of the coronaries or the heart structures in the setting of acute nonspecific chest pain with low probability of CAD. MRA Chest Without IV Contrast MRA has potential uses in the nonischemic setting if acute thoracic aorta conditions, including dissection or intramural hematoma, or aneurysm or pulmonary embolism are being considered [40]. There is no relevant literature to support the use of MRA chest without IV contrast for the evaluation of the coronaries or the heart structures in the setting of acute nonspecific chest pain with low probability of CAD. MRI Heart Function and Morphology Without IV Contrast Pericarditis, as a cause of chest pain, can be potentially excluded by direct assessment of pericardial thickness on noncontrast MRI heart function and morphology images [41]. Characterization of other myocardial and pericardial conditions would optimally require administration of a gadolinium contrast agent. There is no relevant literature to support the use of MRI as an initial imaging test in the patient with acute nonspecific chest pain with a low probability of CAD. MRI Heart Function and Morphology Without and With IV Contrast Although there has been increasing use of MRI with a contrast agent to document clinically suspected myocarditis in patients who have been ruled out for acute myocardial infarction, these are typically patients who have had elevated troponins and thus would not fall in the low probability category [42,43].
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Acute Nonspecific Chest Pain Low Probability of Coronary Artery Disease PCAs. MRA Chest Without and With IV Contrast MR angiography (MRA) has potential uses in the nonischemic setting if acute thoracic aorta conditions, including dissection or intramural hematoma, or aneurysm or pulmonary embolism are being considered [40]. There is no relevant literature to support the use of MRA chest without and with IV contrast for the evaluation of the coronaries or the heart structures in the setting of acute nonspecific chest pain with low probability of CAD. MRA Chest Without IV Contrast MRA has potential uses in the nonischemic setting if acute thoracic aorta conditions, including dissection or intramural hematoma, or aneurysm or pulmonary embolism are being considered [40]. There is no relevant literature to support the use of MRA chest without IV contrast for the evaluation of the coronaries or the heart structures in the setting of acute nonspecific chest pain with low probability of CAD. MRI Heart Function and Morphology Without IV Contrast Pericarditis, as a cause of chest pain, can be potentially excluded by direct assessment of pericardial thickness on noncontrast MRI heart function and morphology images [41]. Characterization of other myocardial and pericardial conditions would optimally require administration of a gadolinium contrast agent. There is no relevant literature to support the use of MRI as an initial imaging test in the patient with acute nonspecific chest pain with a low probability of CAD. MRI Heart Function and Morphology Without and With IV Contrast Although there has been increasing use of MRI with a contrast agent to document clinically suspected myocarditis in patients who have been ruled out for acute myocardial infarction, these are typically patients who have had elevated troponins and thus would not fall in the low probability category [42,43].
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69401
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acrac_69401_7
|
Acute Nonspecific Chest Pain Low Probability of Coronary Artery Disease PCAs
|
A recent review article has reported on the utility of MRI heart function and morphology without and with IV contrast as a prognosticator of myocardial damage and its complications in the clinical setting of acute coronary syndrome; however, such patients Acute Nonspecific Chest Pain typically present with signs or symptoms of myocardial ischemia, unlike the nonspecific signs and symptoms of the cohort of the present topic [41]. There is no relevant literature to support the use of MRI as an initial imaging test in the patient with acute nonspecific chest pain with a low probability of CAD. In this clinical scenario, the presentation and etiology, although not common, can be occasionally useful in the appropriate setting. MRI Heart With Function and Vasodilator Stress Perfusion Without and With IV Contrast Vasodilator stress challenge with first-pass perfusion imaging, rather than inotropic stress, can be used to assess for the evaluation of myocardial ischemia [31]. There is no relevant literature to support the use of MRI as an initial imaging test in the patient with acute nonspecific chest pain with a low probability of CAD. MRI Heart With Function and Inotropic Stress Without IV Contrast An inotropic stress challenge with assessment of wall contractile function, rather than vasodilator stress, can be used to assess for the evaluation of myocardial ischemia [31]. There is no relevant literature to support the use of MRI as an initial imaging test in the patient with acute nonspecific chest pain with a low probability of CAD. MRI Heart With Function and Inotropic Stress Without and With IV Contrast There is no relevant literature to support the use of MRI as an initial imaging test in the patient with acute nonspecific chest pain with a low probability of CAD.
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Acute Nonspecific Chest Pain Low Probability of Coronary Artery Disease PCAs. A recent review article has reported on the utility of MRI heart function and morphology without and with IV contrast as a prognosticator of myocardial damage and its complications in the clinical setting of acute coronary syndrome; however, such patients Acute Nonspecific Chest Pain typically present with signs or symptoms of myocardial ischemia, unlike the nonspecific signs and symptoms of the cohort of the present topic [41]. There is no relevant literature to support the use of MRI as an initial imaging test in the patient with acute nonspecific chest pain with a low probability of CAD. In this clinical scenario, the presentation and etiology, although not common, can be occasionally useful in the appropriate setting. MRI Heart With Function and Vasodilator Stress Perfusion Without and With IV Contrast Vasodilator stress challenge with first-pass perfusion imaging, rather than inotropic stress, can be used to assess for the evaluation of myocardial ischemia [31]. There is no relevant literature to support the use of MRI as an initial imaging test in the patient with acute nonspecific chest pain with a low probability of CAD. MRI Heart With Function and Inotropic Stress Without IV Contrast An inotropic stress challenge with assessment of wall contractile function, rather than vasodilator stress, can be used to assess for the evaluation of myocardial ischemia [31]. There is no relevant literature to support the use of MRI as an initial imaging test in the patient with acute nonspecific chest pain with a low probability of CAD. MRI Heart With Function and Inotropic Stress Without and With IV Contrast There is no relevant literature to support the use of MRI as an initial imaging test in the patient with acute nonspecific chest pain with a low probability of CAD.
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69401
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acrac_69401_8
|
Acute Nonspecific Chest Pain Low Probability of Coronary Artery Disease PCAs
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MRA Coronary Arteries Without and With IV Contrast There is no relevant literature to support the use of MRA coronary arteries without and with IV contrast in the initial imaging evaluation of acute nonspecific chest pain with low probability of CAD. MRA Coronary Arteries Without IV Contrast There is no relevant literature to support the use of MRA coronary arteries without IV contrast in the initial imaging evaluation of acute nonspecific chest pain with low probability of CAD. Arteriography Coronary In the acute chest pain setting, invasive coronary angiography is typically undertaken in patients with elevated troponins when there is concern for an acute myocardial infarction/ischemia. There are limited data on its use in the low pretest probability setting of CAD without signs of myocardial ischemia or infarction. Recent studies have proposed triaging of patients for invasive coronary angiography using ischemia stress testing or, alternatively, CCTA coronary anatomy characterization prior to invasive angiography to increase the diagnostic yield [44]. Radiography Ribs and Thoracic Spine Musculoskeletal conditions such as rib fractures can be identified using radiographs, ideally justified by localized pain symptoms. Conditions that may cause thoracic pain such as scoliosis or diffuse idiopathic skeletal hyperostosis are findings that may be detected incidentally on such an examination. There is no relevant literature to support the use of radiographs of the ribs or thoracic spine in the evaluation of acute nonspecific chest pain with low probability of CAD as an initial imaging test. Nuclear Medicine Scan Gallbladder History, physical examination, and subsequent laboratory markers may implicate upper abdomen solid organs as a potential source of nonspecific chest pain. Abdominal ultrasonography is an efficient means of excluding acute cholecystitis as a source of chest pain in the acute setting.
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Acute Nonspecific Chest Pain Low Probability of Coronary Artery Disease PCAs. MRA Coronary Arteries Without and With IV Contrast There is no relevant literature to support the use of MRA coronary arteries without and with IV contrast in the initial imaging evaluation of acute nonspecific chest pain with low probability of CAD. MRA Coronary Arteries Without IV Contrast There is no relevant literature to support the use of MRA coronary arteries without IV contrast in the initial imaging evaluation of acute nonspecific chest pain with low probability of CAD. Arteriography Coronary In the acute chest pain setting, invasive coronary angiography is typically undertaken in patients with elevated troponins when there is concern for an acute myocardial infarction/ischemia. There are limited data on its use in the low pretest probability setting of CAD without signs of myocardial ischemia or infarction. Recent studies have proposed triaging of patients for invasive coronary angiography using ischemia stress testing or, alternatively, CCTA coronary anatomy characterization prior to invasive angiography to increase the diagnostic yield [44]. Radiography Ribs and Thoracic Spine Musculoskeletal conditions such as rib fractures can be identified using radiographs, ideally justified by localized pain symptoms. Conditions that may cause thoracic pain such as scoliosis or diffuse idiopathic skeletal hyperostosis are findings that may be detected incidentally on such an examination. There is no relevant literature to support the use of radiographs of the ribs or thoracic spine in the evaluation of acute nonspecific chest pain with low probability of CAD as an initial imaging test. Nuclear Medicine Scan Gallbladder History, physical examination, and subsequent laboratory markers may implicate upper abdomen solid organs as a potential source of nonspecific chest pain. Abdominal ultrasonography is an efficient means of excluding acute cholecystitis as a source of chest pain in the acute setting.
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69401
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acrac_3194112_0
|
Screening for Abdominal Aortic Aneurysm
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CT Abdomen and Pelvis With IV Contrast As mentioned from the CT angiography (CTA) abdomen and pelvis without and with intravenous (IV) contrast section below, contrast-enhanced CT scans have not been generally accepted as a first-line screening tool for AAA [13]. Increasing number of abdominal CT scans in most hospitals results in diagnosis of many incidental AAAs. Retrospective review studies of abdominal CT scans done for a variety of reasons showed a prevalence of 2.2% to 5.8% for AAA [14,15]. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through representation of such organizations on expert panels. Participation on the expert panel does not necessarily imply endorsement of the final document by individual contributors or their respective organization. Reprint requests to: [email protected] Screening for Abdominal Aortic Aneurysm CT Abdomen and Pelvis Without and With IV Contrast Again, as mentioned from the CTA abdomen and pelvis without and with IV contrast section below, contrast- enhanced CT scans have not been generally accepted as a first-line screening tool for AAA [13]. CT Abdomen and Pelvis Without IV Contrast Noncontrast CT can be considered as a screening examination for AAA, which can be especially beneficial in the setting of obesity or poor sonographic window. One study reported that noncontrast CT was superior to ultrasound (US) concerning sensitivity ranging from 83% to 89% depending on the measured plane when compared to US with 57% to 70%, although specificity was high for both studies measuring 98% and 99%, respectively [13]. With modern CT imaging technology, noncontrast CT has been proposed as an alternative screening method to offer more reliable examinations with additional information, including aortic wall calcifications, as well as thoracic and iliac aortic abnormality [13].
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Screening for Abdominal Aortic Aneurysm. CT Abdomen and Pelvis With IV Contrast As mentioned from the CT angiography (CTA) abdomen and pelvis without and with intravenous (IV) contrast section below, contrast-enhanced CT scans have not been generally accepted as a first-line screening tool for AAA [13]. Increasing number of abdominal CT scans in most hospitals results in diagnosis of many incidental AAAs. Retrospective review studies of abdominal CT scans done for a variety of reasons showed a prevalence of 2.2% to 5.8% for AAA [14,15]. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through representation of such organizations on expert panels. Participation on the expert panel does not necessarily imply endorsement of the final document by individual contributors or their respective organization. Reprint requests to: [email protected] Screening for Abdominal Aortic Aneurysm CT Abdomen and Pelvis Without and With IV Contrast Again, as mentioned from the CTA abdomen and pelvis without and with IV contrast section below, contrast- enhanced CT scans have not been generally accepted as a first-line screening tool for AAA [13]. CT Abdomen and Pelvis Without IV Contrast Noncontrast CT can be considered as a screening examination for AAA, which can be especially beneficial in the setting of obesity or poor sonographic window. One study reported that noncontrast CT was superior to ultrasound (US) concerning sensitivity ranging from 83% to 89% depending on the measured plane when compared to US with 57% to 70%, although specificity was high for both studies measuring 98% and 99%, respectively [13]. With modern CT imaging technology, noncontrast CT has been proposed as an alternative screening method to offer more reliable examinations with additional information, including aortic wall calcifications, as well as thoracic and iliac aortic abnormality [13].
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3194112
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acrac_3194112_1
|
Screening for Abdominal Aortic Aneurysm
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When compared to CTA, a study reported that the low-dose noncontrast CT exhibited similar accuracy and reproducibility of measurements in AAA [16]. CTA Abdomen and Pelvis With IV Contrast Contrast-enhanced CT scans are known to be more precise when compared to US, with near 100% sensitivity and specificity, and are more reliable than US at determining size and extent and demonstrating adjacent structures, and are not degraded by bowel gas or obesity. Although contrast-enhanced CTA is an effective diagnostic tool, it has not been generally accepted as a screening tool due to its use of IV contrast [12,13]. CTA imaging of AAA is now well-established and is a popular imaging choice for diagnostic and presurgical/intervention study and sometimes surveillance of AAA, with particular strength in demonstrating the size, extent, and other characteristics of an aneurysm and associated aortic branch disease. The difference between US and CTA measurements of AAA were reported, with general accusation that US underestimates AAA diameter and that CT demonstrates a closer reflection of the actual diameter, with parallel debate over the ideal measuring method without complete consensus [17,18]. Recent updates from the 2018 The Society for Vascular Surgery guidelines for the care of AAA patient now recommends using the outer wall to outer wall for measurement of the maximum aneurysm diameter [6], moving away from the inner wall to inner wall measurements. CTA Abdomen and Pelvis Without and With IV Contrast Noncontrast CT scans were not commonly used as a primary screening tool for AAA in the past, but recent studies have explored their potential as an alternative method [13,19]. One such study of 533 patients reported a higher sensitivity (83%-89% versus 57%-70%) with high specificity over 98% when compared to US [12].
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Screening for Abdominal Aortic Aneurysm. When compared to CTA, a study reported that the low-dose noncontrast CT exhibited similar accuracy and reproducibility of measurements in AAA [16]. CTA Abdomen and Pelvis With IV Contrast Contrast-enhanced CT scans are known to be more precise when compared to US, with near 100% sensitivity and specificity, and are more reliable than US at determining size and extent and demonstrating adjacent structures, and are not degraded by bowel gas or obesity. Although contrast-enhanced CTA is an effective diagnostic tool, it has not been generally accepted as a screening tool due to its use of IV contrast [12,13]. CTA imaging of AAA is now well-established and is a popular imaging choice for diagnostic and presurgical/intervention study and sometimes surveillance of AAA, with particular strength in demonstrating the size, extent, and other characteristics of an aneurysm and associated aortic branch disease. The difference between US and CTA measurements of AAA were reported, with general accusation that US underestimates AAA diameter and that CT demonstrates a closer reflection of the actual diameter, with parallel debate over the ideal measuring method without complete consensus [17,18]. Recent updates from the 2018 The Society for Vascular Surgery guidelines for the care of AAA patient now recommends using the outer wall to outer wall for measurement of the maximum aneurysm diameter [6], moving away from the inner wall to inner wall measurements. CTA Abdomen and Pelvis Without and With IV Contrast Noncontrast CT scans were not commonly used as a primary screening tool for AAA in the past, but recent studies have explored their potential as an alternative method [13,19]. One such study of 533 patients reported a higher sensitivity (83%-89% versus 57%-70%) with high specificity over 98% when compared to US [12].
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3194112
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acrac_3194112_2
|
Screening for Abdominal Aortic Aneurysm
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The added benefit of the noncontrast CT when performed in addition to the CTA is that it allows for a more accurate detection of aneurysm calcification and thoracic and iliac lesions compared to US. MRA Abdomen and Pelvis With IV Contrast Similar to the CT, MR angiography (MRA) is also highly accurate in detecting AAA and shows excellent reproducibility in between MRI examinations but has not been accepted as a screening tool [13]. MRA can serve as an alternative tool for CT or US. MRA has the potential to provide further information on AAA beyond its morphology, for example, AAA wall strain and stiffness, which may contribute to better understanding of AAA pathophysiology, biomechanics, and risk for rupture [20]. MRA Abdomen and Pelvis Without and With IV Contrast There is insufficient evidence to support noncontrast MRA as a screening examination for AAA. However, a prospective study of nonenhanced MRA compared with contrast-enhanced CTA demonstrated equivalent accuracy of measurements in preoperative planning for endovascular aortic repair (EVAR) of AAA [21]. Noncontrast MRA sequences such as 3-D noncontrast black-blood cardiovascular MR technique has been studied with compressed sensing to decrease its long scan time [22]. MRA Abdomen and Pelvis Without IV Contrast There is insufficient evidence to support the use of a noncontrast MRA as a screening examination for AAA. MRI Abdomen and Pelvis With IV Contrast There is insufficient evidence to support the use of MRI that lacks MRA sequences as a screening examination for AAA. Screening for Abdominal Aortic Aneurysm MRI Abdomen and Pelvis Without and With IV Contrast There is insufficient evidence to support the addition of a noncontrast MRI as a screening examination for AAA. MRI Abdomen and Pelvis Without IV Contrast There is insufficient evidence to support a noncontrast MRI as a screening examination for AAA.
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Screening for Abdominal Aortic Aneurysm. The added benefit of the noncontrast CT when performed in addition to the CTA is that it allows for a more accurate detection of aneurysm calcification and thoracic and iliac lesions compared to US. MRA Abdomen and Pelvis With IV Contrast Similar to the CT, MR angiography (MRA) is also highly accurate in detecting AAA and shows excellent reproducibility in between MRI examinations but has not been accepted as a screening tool [13]. MRA can serve as an alternative tool for CT or US. MRA has the potential to provide further information on AAA beyond its morphology, for example, AAA wall strain and stiffness, which may contribute to better understanding of AAA pathophysiology, biomechanics, and risk for rupture [20]. MRA Abdomen and Pelvis Without and With IV Contrast There is insufficient evidence to support noncontrast MRA as a screening examination for AAA. However, a prospective study of nonenhanced MRA compared with contrast-enhanced CTA demonstrated equivalent accuracy of measurements in preoperative planning for endovascular aortic repair (EVAR) of AAA [21]. Noncontrast MRA sequences such as 3-D noncontrast black-blood cardiovascular MR technique has been studied with compressed sensing to decrease its long scan time [22]. MRA Abdomen and Pelvis Without IV Contrast There is insufficient evidence to support the use of a noncontrast MRA as a screening examination for AAA. MRI Abdomen and Pelvis With IV Contrast There is insufficient evidence to support the use of MRI that lacks MRA sequences as a screening examination for AAA. Screening for Abdominal Aortic Aneurysm MRI Abdomen and Pelvis Without and With IV Contrast There is insufficient evidence to support the addition of a noncontrast MRI as a screening examination for AAA. MRI Abdomen and Pelvis Without IV Contrast There is insufficient evidence to support a noncontrast MRI as a screening examination for AAA.
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3194112
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acrac_69455_0
|
Incidentally Detected Indeterminate Pulmonary Nodule PCAs
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Introduction/Background A pulmonary nodule is defined as a well or poorly defined rounded opacity measuring <3 cm in diameter [1-5]. Nodules are classified as solid, part-solid, and ground-glass on CT, based on their attenuation, allowing for a more accurate assessment of malignancy risk. Ground-glass nodules are areas of increased attenuation through which underlying structures such as vessels remain visible [3]. Incidental pulmonary nodules are common, with reported frequencies ranging from 5.6% to 51% on CT and 0.1% to 7% on chest radiographs [5-7]. While it is estimated that 70% to 97% of incidental pulmonary nodules are benign [8], most are indeterminate for malignancy when first encountered making their management challenging. Additional methods that can enhance the detection and characterization of lung nodules include computer-aided detection systems [18-20], pulmonary vessel subtraction [21,22], deep convolutional neural networks [23], and other artificial intelligence algorithms [24]. While some practices use these methods, a detailed discussion falls outside of the scope of this document. aUniversity of Wisconsin School of Medicine and Public Health, Madison, Wisconsin. bPanel Chair, Duke University, Durham, North Carolina. cStanford University Medical Center, Stanford, California; The Society of Thoracic Surgeons. dMayo Clinic, Rochester, Minnesota; Commission on Nuclear Medicine and Molecular Imaging. eEmory University Hospital, Atlanta, Georgia. fNew York University Langone Health, New York, New York; IF Committee. gHampton VA Medical Center, Hampton, Virginia. hUniversity of Michigan Health System, Ann Arbor, Michigan. iVanderbilt University Medical Center, Nashville, Tennessee; American College of Chest Physicians. jUniversity of Arizona College of Medicine, Phoenix, Arizona. kMedical University of South Carolina, Charleston, South Carolina; IF Committee. lMallinckrodt Institute of Radiology, Saint Louis, Missouri.
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Incidentally Detected Indeterminate Pulmonary Nodule PCAs. Introduction/Background A pulmonary nodule is defined as a well or poorly defined rounded opacity measuring <3 cm in diameter [1-5]. Nodules are classified as solid, part-solid, and ground-glass on CT, based on their attenuation, allowing for a more accurate assessment of malignancy risk. Ground-glass nodules are areas of increased attenuation through which underlying structures such as vessels remain visible [3]. Incidental pulmonary nodules are common, with reported frequencies ranging from 5.6% to 51% on CT and 0.1% to 7% on chest radiographs [5-7]. While it is estimated that 70% to 97% of incidental pulmonary nodules are benign [8], most are indeterminate for malignancy when first encountered making their management challenging. Additional methods that can enhance the detection and characterization of lung nodules include computer-aided detection systems [18-20], pulmonary vessel subtraction [21,22], deep convolutional neural networks [23], and other artificial intelligence algorithms [24]. While some practices use these methods, a detailed discussion falls outside of the scope of this document. aUniversity of Wisconsin School of Medicine and Public Health, Madison, Wisconsin. bPanel Chair, Duke University, Durham, North Carolina. cStanford University Medical Center, Stanford, California; The Society of Thoracic Surgeons. dMayo Clinic, Rochester, Minnesota; Commission on Nuclear Medicine and Molecular Imaging. eEmory University Hospital, Atlanta, Georgia. fNew York University Langone Health, New York, New York; IF Committee. gHampton VA Medical Center, Hampton, Virginia. hUniversity of Michigan Health System, Ann Arbor, Michigan. iVanderbilt University Medical Center, Nashville, Tennessee; American College of Chest Physicians. jUniversity of Arizona College of Medicine, Phoenix, Arizona. kMedical University of South Carolina, Charleston, South Carolina; IF Committee. lMallinckrodt Institute of Radiology, Saint Louis, Missouri.
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Incidentally Detected Indeterminate Pulmonary Nodule PCAs
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mJohn H. Stroger, Jr. Hospital of Cook County, Chicago, Illinois; American College of Physicians. nNational Institutes of Health, Bethesda, Maryland. oLoyola University Chicago, Stritch School of Medicine, Department of Radiation Oncology, Cardinal Bernardin Cancer Center, Maywood, Illinois; Commission on Radiation Oncology. pDuke University School of Medicine, Durham, North Carolina; The Society of Thoracic Surgeons. qThe University of Texas MD Anderson Cancer Center, Houston, Texas. rSpecialty Chair, Ohio State University Wexner Medical Center, Columbus, Ohio. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through representation of such organizations on expert panels. Participation on the expert panel does not necessarily imply endorsement of the final document by individual contributors or their respective organization. Reprint requests to: [email protected] Incidentally Detected Indeterminate Pulmonary Nodule Discussion of Procedures by Variant Variant 1: Adult greater than or equal to 35 years of age. Incidentally detected indeterminate pulmonary nodule on chest radiograph. Next imaging study. CT Chest Without IV Contrast For individuals with an indeterminate pulmonary nodule detected on chest radiograph, ACCP guidelines recommend reviewing prior studies to determine stability. If the nodule has been stable for at least 2 years, no further workup is advised. If stability cannot be determined, guidelines recommend performing a chest CT to better characterize the nodule [2]. There are advantages of using CT as the first step in the characterization of pulmonary nodules detected on radio- graphs. Overlapping structures that might be causing pseudonodules are removed. Certain nodule characteristics suggestive of benign etiology are better appreciated by CT and can avoid additional workup.
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Incidentally Detected Indeterminate Pulmonary Nodule PCAs. mJohn H. Stroger, Jr. Hospital of Cook County, Chicago, Illinois; American College of Physicians. nNational Institutes of Health, Bethesda, Maryland. oLoyola University Chicago, Stritch School of Medicine, Department of Radiation Oncology, Cardinal Bernardin Cancer Center, Maywood, Illinois; Commission on Radiation Oncology. pDuke University School of Medicine, Durham, North Carolina; The Society of Thoracic Surgeons. qThe University of Texas MD Anderson Cancer Center, Houston, Texas. rSpecialty Chair, Ohio State University Wexner Medical Center, Columbus, Ohio. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through representation of such organizations on expert panels. Participation on the expert panel does not necessarily imply endorsement of the final document by individual contributors or their respective organization. Reprint requests to: [email protected] Incidentally Detected Indeterminate Pulmonary Nodule Discussion of Procedures by Variant Variant 1: Adult greater than or equal to 35 years of age. Incidentally detected indeterminate pulmonary nodule on chest radiograph. Next imaging study. CT Chest Without IV Contrast For individuals with an indeterminate pulmonary nodule detected on chest radiograph, ACCP guidelines recommend reviewing prior studies to determine stability. If the nodule has been stable for at least 2 years, no further workup is advised. If stability cannot be determined, guidelines recommend performing a chest CT to better characterize the nodule [2]. There are advantages of using CT as the first step in the characterization of pulmonary nodules detected on radio- graphs. Overlapping structures that might be causing pseudonodules are removed. Certain nodule characteristics suggestive of benign etiology are better appreciated by CT and can avoid additional workup.
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Incidentally Detected Indeterminate Pulmonary Nodule PCAs
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For example, diffuse, central, laminated, or popcorn calcifications patterns are predictors of benign etiology (odds ratio [OR] = 0.07-0.20) [28]. Macroscopic fat is another indicator of benign etiology typical of hamartomas, which cannot be appreciated on radiographs. The mean attenuation value of indeterminate benign and malignant nodules on unenhanced CT is not significantly different and therefore not useful in their differentiation. However, multiple imaging features that increase the risk of malignancy are best characterized on CT, including nodule size, morphology, location, multi- plicity, or the presence of emphysema or fibrosis. Unsuspected associated processes such as lymphadenopathy can sometimes be detected on CT, and CT can help with planning next steps such as biopsy when indicated [2]. CT Chest Without and With IV Contrast There is no relevant literature to support the use of dynamic contrast-enhanced CT in the initial evaluation of incidentally detected indeterminate pulmonary nodules on chest radiographs. IV contrast is not required to identify or initially characterize pulmonary nodules on CT [27]. CT Chest With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT in the initial evaluation of incidentally detected indeterminate pulmonary nodules on chest radiographs. IV contrast is not required to identify or initially characterize pulmonary nodules on CT [27]. Cancer staging, an incidental mass workup, and nodules with associated lymphadenopathy fall outside of the scope of this document. FDG-PET/CT Whole Body There is no relevant literature to support the use of fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG)-PET/CT in the initial evaluation of incidentally detected indeterminate pulmonary nodules on chest radiographs. FDG-PET/MRI Whole Body There is no relevant literature to support the use of FDG-PET/MRI in the evaluation of incidentally detected indeterminate pulmonary nodules.
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Incidentally Detected Indeterminate Pulmonary Nodule PCAs. For example, diffuse, central, laminated, or popcorn calcifications patterns are predictors of benign etiology (odds ratio [OR] = 0.07-0.20) [28]. Macroscopic fat is another indicator of benign etiology typical of hamartomas, which cannot be appreciated on radiographs. The mean attenuation value of indeterminate benign and malignant nodules on unenhanced CT is not significantly different and therefore not useful in their differentiation. However, multiple imaging features that increase the risk of malignancy are best characterized on CT, including nodule size, morphology, location, multi- plicity, or the presence of emphysema or fibrosis. Unsuspected associated processes such as lymphadenopathy can sometimes be detected on CT, and CT can help with planning next steps such as biopsy when indicated [2]. CT Chest Without and With IV Contrast There is no relevant literature to support the use of dynamic contrast-enhanced CT in the initial evaluation of incidentally detected indeterminate pulmonary nodules on chest radiographs. IV contrast is not required to identify or initially characterize pulmonary nodules on CT [27]. CT Chest With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT in the initial evaluation of incidentally detected indeterminate pulmonary nodules on chest radiographs. IV contrast is not required to identify or initially characterize pulmonary nodules on CT [27]. Cancer staging, an incidental mass workup, and nodules with associated lymphadenopathy fall outside of the scope of this document. FDG-PET/CT Whole Body There is no relevant literature to support the use of fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG)-PET/CT in the initial evaluation of incidentally detected indeterminate pulmonary nodules on chest radiographs. FDG-PET/MRI Whole Body There is no relevant literature to support the use of FDG-PET/MRI in the evaluation of incidentally detected indeterminate pulmonary nodules.
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Incidentally Detected Indeterminate Pulmonary Nodule PCAs
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Image-Guided Transthoracic Needle Biopsy There is no relevant literature to support the use of image-guided transthoracic needle biopsy (TNB) in the initial evaluation of incidentally detected indeterminate pulmonary nodules on chest radiographs. MRI Chest Without IV Contrast There is no relevant literature to support the use of MRI chest in the initial evaluation of incidentally detected indeterminate pulmonary nodules on chest radiographs. Incidentally Detected Indeterminate Pulmonary Nodule MRI Chest Without and With IV Contrast There is no relevant literature to support the use of dynamic MRI chest in the initial evaluation of incidentally detected indeterminate pulmonary nodules on chest radiographs. Radiography Chest About 20% of suspected nodules on chest radiographs prove to be pseudonodules. These are generally caused by rib fractures, skin lesions, anatomic variants, or overlapping structures [25]. Repeat radiographs with nipple markers, chest fluoroscopy, oblique chest views, and dual-energy subtraction radiography have been described to help distinguish between a pulmonary nodule and a pseudonodule to avoid additional or invasive workup [25]. There is insufficient literature to support their widespread use, and validation studies are needed to measure the effectiveness of newer techniques like dual-energy subtraction. Despite the lack of sufficient literature supporting these methods, the panel consensus was that a repeat chest radiograph is a common practice and may be a useful next step when a pseudonodule is suspected on a radiograph. When encountering indeterminate solid nodules on chest radiograph, ACCP guidelines recommend thin-section chest CT as the next step unless prior imaging is available to prove stability over 2 years (grade 1C recommendation) [2]. The purpose is to better characterize the nodule and asses its malignant potential.
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Incidentally Detected Indeterminate Pulmonary Nodule PCAs. Image-Guided Transthoracic Needle Biopsy There is no relevant literature to support the use of image-guided transthoracic needle biopsy (TNB) in the initial evaluation of incidentally detected indeterminate pulmonary nodules on chest radiographs. MRI Chest Without IV Contrast There is no relevant literature to support the use of MRI chest in the initial evaluation of incidentally detected indeterminate pulmonary nodules on chest radiographs. Incidentally Detected Indeterminate Pulmonary Nodule MRI Chest Without and With IV Contrast There is no relevant literature to support the use of dynamic MRI chest in the initial evaluation of incidentally detected indeterminate pulmonary nodules on chest radiographs. Radiography Chest About 20% of suspected nodules on chest radiographs prove to be pseudonodules. These are generally caused by rib fractures, skin lesions, anatomic variants, or overlapping structures [25]. Repeat radiographs with nipple markers, chest fluoroscopy, oblique chest views, and dual-energy subtraction radiography have been described to help distinguish between a pulmonary nodule and a pseudonodule to avoid additional or invasive workup [25]. There is insufficient literature to support their widespread use, and validation studies are needed to measure the effectiveness of newer techniques like dual-energy subtraction. Despite the lack of sufficient literature supporting these methods, the panel consensus was that a repeat chest radiograph is a common practice and may be a useful next step when a pseudonodule is suspected on a radiograph. When encountering indeterminate solid nodules on chest radiograph, ACCP guidelines recommend thin-section chest CT as the next step unless prior imaging is available to prove stability over 2 years (grade 1C recommendation) [2]. The purpose is to better characterize the nodule and asses its malignant potential.
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Incidentally Detected Indeterminate Pulmonary Nodule PCAs
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To our knowledge, there is no relevant literature describing effective ways to discriminate between benign and malignant nodules on radiographs [2]. The mean attenuation value of indeterminate benign and malignant nodules on unenhanced CT is not significantly different and therefore not useful in their differentiation. However, multiple imaging features that increase the risk of malignancy are best characterized on CT including nodule size, morphology, location, multiplicity, or the presence of emphysema or fibrosis. Even though nodules <6 mm have a malignancy risk <1%, an optional follow- up CT can be recommended if some of these features are present (see Appendix 1). CT Chest With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT in the evaluation of incidentally detected indeterminate pulmonary nodules measuring <6 mm on chest CT. IV contrast is not required to identify or determine stability of pulmonary nodules [27]. FDG-PET/MRI Whole Body There is no relevant literature to support the use of FDG-PET/MRI in the evaluation of incidentally detected indeterminate pulmonary nodules. MRI Chest Without IV Contrast There is no relevant literature to support the use of MRI chest in the evaluation of incidentally detected indeterminate pulmonary nodules measuring <6 mm on chest CT. MRI Chest Without and With IV Contrast There is no relevant literature to support the use of dynamic MRI chest in the evaluation of incidentally detected indeterminate pulmonary nodules measuring <6 mm on chest CT. Female sex is included in the Brock University prediction model as a predictor of lung cancer [28]. Our literature search included a study by Chilet-Rosell et al [33] evaluating management differences between 545 men and 347 women from two institutions following the detection of incidental pulmonary nodules over 5 years. If the nodule was detected by CT, men were more likely to have immediate testing than women (P < .
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Incidentally Detected Indeterminate Pulmonary Nodule PCAs. To our knowledge, there is no relevant literature describing effective ways to discriminate between benign and malignant nodules on radiographs [2]. The mean attenuation value of indeterminate benign and malignant nodules on unenhanced CT is not significantly different and therefore not useful in their differentiation. However, multiple imaging features that increase the risk of malignancy are best characterized on CT including nodule size, morphology, location, multiplicity, or the presence of emphysema or fibrosis. Even though nodules <6 mm have a malignancy risk <1%, an optional follow- up CT can be recommended if some of these features are present (see Appendix 1). CT Chest With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT in the evaluation of incidentally detected indeterminate pulmonary nodules measuring <6 mm on chest CT. IV contrast is not required to identify or determine stability of pulmonary nodules [27]. FDG-PET/MRI Whole Body There is no relevant literature to support the use of FDG-PET/MRI in the evaluation of incidentally detected indeterminate pulmonary nodules. MRI Chest Without IV Contrast There is no relevant literature to support the use of MRI chest in the evaluation of incidentally detected indeterminate pulmonary nodules measuring <6 mm on chest CT. MRI Chest Without and With IV Contrast There is no relevant literature to support the use of dynamic MRI chest in the evaluation of incidentally detected indeterminate pulmonary nodules measuring <6 mm on chest CT. Female sex is included in the Brock University prediction model as a predictor of lung cancer [28]. Our literature search included a study by Chilet-Rosell et al [33] evaluating management differences between 545 men and 347 women from two institutions following the detection of incidental pulmonary nodules over 5 years. If the nodule was detected by CT, men were more likely to have immediate testing than women (P < .
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Incidentally Detected Indeterminate Pulmonary Nodule PCAs
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001), and women were followed-up more frequently than men (P < . 001). In the multivariate analysis adjusted by age, smoking status, chronic obstructive pulmonary disease, and nodule characteristics, women were still more likely than men to be followed-up (P = . 002). The median time between nodule detection and those diagnosed with lung cancer was 1.5 months for men and 4.2 months for women (no statistical difference). Authors raise the question that management variability could be related to a false belief that lung cancer is considered a disease of men. This was a small study, and further research exploring management differences are warranted to better understand the impact of sex in the management of lung nodules. Vascularity differences between benign and malignant nodules have been described showing that malignant nodules are more vascular [30]. Nodule enhancement, which reflects vascularity, can be quantified with dynamic contrast- enhanced CT. This technique is highly sensitive in detecting malignant nodules but is nonspecific, mainly because of active inflammatory and infectious nodules also showing high vascularity [2,28]. Different enhancement cut-off values have been proposed to help with this problem. Lower cut-offs generally come with higher sensitivity but decreased specificity. Perfusion values are also influenced by technique, highlighting the need to be cautious when generalizing study results [34]. Incidentally Detected Indeterminate Pulmonary Nodule selection bias. Radiation dose was also discussed, suggesting their technique might not be appropriate for women with low pretest probability of malignancy [29]. Several other series have reported low specificity values [2,32]. Although enhancement patterns of solid nodules have been widely studied, this is not the case for part-solid nodules.
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Incidentally Detected Indeterminate Pulmonary Nodule PCAs. 001), and women were followed-up more frequently than men (P < . 001). In the multivariate analysis adjusted by age, smoking status, chronic obstructive pulmonary disease, and nodule characteristics, women were still more likely than men to be followed-up (P = . 002). The median time between nodule detection and those diagnosed with lung cancer was 1.5 months for men and 4.2 months for women (no statistical difference). Authors raise the question that management variability could be related to a false belief that lung cancer is considered a disease of men. This was a small study, and further research exploring management differences are warranted to better understand the impact of sex in the management of lung nodules. Vascularity differences between benign and malignant nodules have been described showing that malignant nodules are more vascular [30]. Nodule enhancement, which reflects vascularity, can be quantified with dynamic contrast- enhanced CT. This technique is highly sensitive in detecting malignant nodules but is nonspecific, mainly because of active inflammatory and infectious nodules also showing high vascularity [2,28]. Different enhancement cut-off values have been proposed to help with this problem. Lower cut-offs generally come with higher sensitivity but decreased specificity. Perfusion values are also influenced by technique, highlighting the need to be cautious when generalizing study results [34]. Incidentally Detected Indeterminate Pulmonary Nodule selection bias. Radiation dose was also discussed, suggesting their technique might not be appropriate for women with low pretest probability of malignancy [29]. Several other series have reported low specificity values [2,32]. Although enhancement patterns of solid nodules have been widely studied, this is not the case for part-solid nodules.
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Incidentally Detected Indeterminate Pulmonary Nodule PCAs
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Cohen et al [35] retrospectively studied the differences in semiautomated attenuation measurements on unenhanced and enhanced CTs of 53 adenocarcinomas presenting as part-solid nodules. The study showed that most parameters were significantly increased on enhanced CT, including longest transverse diameter of the whole nodule, the solid component, nodule volume and mass, solid component volume and mass, and nodule attenuation. The only parameter that was not significantly elevated was the solid component attenuation, highlighting that caution must be taken when comparing part-solid nodules obtained on studies with and without IV contrast. The role of FDG-PET/CT in the differentiation of benign from malignant nodules has been extensively studied and relies on measuring glucose metabolism, which is typically elevated on malignant lesions. Reported sensitivities and specificities range from 88% to 96% and 77% to 88%, respectively [1,5,32]. Given PET limited spatial resolution, its use in the management of incidental pulmonary nodules is suggested for nodules >0.8 cm [2,9,40]. Nodule size (generally >0.8 cm), nodule attenuation, selected patient cohorts, how a malignant nodule is defined, Incidentally Detected Indeterminate Pulmonary Nodule and technical factors vary by study and should be considered when making conclusions about reported sensitivities and specificities. PET/CT and contrast-enhanced CT have been compared for the evaluation of solitary pulmonary nodules on small series, with results favoring PET/CT over dynamic CT. Christensen et al [36] showed sensitivities and specificities of 96% and 76% for PET/CT versus 100% and 29% for dynamic CT. Yi et al showed sensitivity, specificity, and accuracy of 96%, 88%, and 93% for PET/CT versus 81%, 93%, and 85% for dynamic CT, respectively [5,32]. False-negative results on PET/CT go beyond small nodule size (<0.8 cm).
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Incidentally Detected Indeterminate Pulmonary Nodule PCAs. Cohen et al [35] retrospectively studied the differences in semiautomated attenuation measurements on unenhanced and enhanced CTs of 53 adenocarcinomas presenting as part-solid nodules. The study showed that most parameters were significantly increased on enhanced CT, including longest transverse diameter of the whole nodule, the solid component, nodule volume and mass, solid component volume and mass, and nodule attenuation. The only parameter that was not significantly elevated was the solid component attenuation, highlighting that caution must be taken when comparing part-solid nodules obtained on studies with and without IV contrast. The role of FDG-PET/CT in the differentiation of benign from malignant nodules has been extensively studied and relies on measuring glucose metabolism, which is typically elevated on malignant lesions. Reported sensitivities and specificities range from 88% to 96% and 77% to 88%, respectively [1,5,32]. Given PET limited spatial resolution, its use in the management of incidental pulmonary nodules is suggested for nodules >0.8 cm [2,9,40]. Nodule size (generally >0.8 cm), nodule attenuation, selected patient cohorts, how a malignant nodule is defined, Incidentally Detected Indeterminate Pulmonary Nodule and technical factors vary by study and should be considered when making conclusions about reported sensitivities and specificities. PET/CT and contrast-enhanced CT have been compared for the evaluation of solitary pulmonary nodules on small series, with results favoring PET/CT over dynamic CT. Christensen et al [36] showed sensitivities and specificities of 96% and 76% for PET/CT versus 100% and 29% for dynamic CT. Yi et al showed sensitivity, specificity, and accuracy of 96%, 88%, and 93% for PET/CT versus 81%, 93%, and 85% for dynamic CT, respectively [5,32]. False-negative results on PET/CT go beyond small nodule size (<0.8 cm).
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Incidentally Detected Indeterminate Pulmonary Nodule PCAs
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Certain malignant tumors show low metabolic activity including carcinoid and adenocarcinoma regardless of size (those with predominant ground-glass component, small solid components, and mucinous type). PET/CT is not a reliable test to distinguish benign from malignant ground-glass nodules (or part-solid nodules with small solid components). Because of the indolent behavior of ground-glass nodules, PET/CT sensitivity is low and follow-up chest CT is preferred [9,26-28]. Defective technique can also result in false-negative studies [4,41,42]. False-positive results on PET/CT also exist, mostly infectious and inflammatory lesions and less frequently sarcoidosis and rheumatoid nodules. Decreased FDG-PET/CT specificity to differentiate benign from malignant nodules has been recognized in regions with high prevalence of lung infections and reported as low as 25% in areas of endemic tuberculosis [40,43]. A meta-analysis of 70 studies showed FDG-PET/CT specificity adjusted for endemic infectious lung disease was 61% (95% CI, 49%-72%) compared to nonendemic regions 77% (95% CI, 73%-80%) [40,44]. Reyes et al [45] conducted a retrospective study comparing 351 biopsy-proven granulomatous and malignant nodules in a coccidioidal endemic region. Authors found that an elevated maximum standardized uptake value (SUVmax) was the only distinguishing feature between benign and malignant nodules. All nodules with SUVmax >5.9 were malignant, but there was overlap in nodules with SUVmax <5.9. Using an SUVmax <5.9, the sensitivity and specificity were 69% and 100%, respectively. This limitation should be recognized in endemic areas because it could alter the choice of next steps to more conservative options such as short-term follow-up CT. FDG-PET/MRI Whole Body There is no relevant literature to support the use of PET/MRI in the initial evaluation of incidentally detected pulmonary nodules. The use of FDG-PET/MRI in humans was first described in the early 2000s.
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Incidentally Detected Indeterminate Pulmonary Nodule PCAs. Certain malignant tumors show low metabolic activity including carcinoid and adenocarcinoma regardless of size (those with predominant ground-glass component, small solid components, and mucinous type). PET/CT is not a reliable test to distinguish benign from malignant ground-glass nodules (or part-solid nodules with small solid components). Because of the indolent behavior of ground-glass nodules, PET/CT sensitivity is low and follow-up chest CT is preferred [9,26-28]. Defective technique can also result in false-negative studies [4,41,42]. False-positive results on PET/CT also exist, mostly infectious and inflammatory lesions and less frequently sarcoidosis and rheumatoid nodules. Decreased FDG-PET/CT specificity to differentiate benign from malignant nodules has been recognized in regions with high prevalence of lung infections and reported as low as 25% in areas of endemic tuberculosis [40,43]. A meta-analysis of 70 studies showed FDG-PET/CT specificity adjusted for endemic infectious lung disease was 61% (95% CI, 49%-72%) compared to nonendemic regions 77% (95% CI, 73%-80%) [40,44]. Reyes et al [45] conducted a retrospective study comparing 351 biopsy-proven granulomatous and malignant nodules in a coccidioidal endemic region. Authors found that an elevated maximum standardized uptake value (SUVmax) was the only distinguishing feature between benign and malignant nodules. All nodules with SUVmax >5.9 were malignant, but there was overlap in nodules with SUVmax <5.9. Using an SUVmax <5.9, the sensitivity and specificity were 69% and 100%, respectively. This limitation should be recognized in endemic areas because it could alter the choice of next steps to more conservative options such as short-term follow-up CT. FDG-PET/MRI Whole Body There is no relevant literature to support the use of PET/MRI in the initial evaluation of incidentally detected pulmonary nodules. The use of FDG-PET/MRI in humans was first described in the early 2000s.
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Incidentally Detected Indeterminate Pulmonary Nodule PCAs
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PET/MRI integrates anatomic and functional MRI data with the metabolic information of PET. Interest around PET/MRI includes functional information and higher soft-tissue contrast resolution. An international survey of active whole- body PET/MRI sites showed oncology as its main application. Perceived challenges to its widespread use included study duration (2 times longer than a typical PET/CT), lack of standardized protocols, and challenges with interpretation (>80% sites had radiologist and nuclear medicine physicians jointly reporting as opposed to 40% for PET/CT) [46]. When imaging the lungs, PET/MRI faces the same challenges as lung MRI. Small nonavid nodules are usually missed, and finding precise anatomic correlates for areas of lung uptake can be difficult. 9 Incidentally Detected Indeterminate Pulmonary Nodule 21.4% of the missed nodules were rated malignant. This resulted in one patient being upstaged from tumor stage I to IV [50]. Further advances on PET/MRI are needed before it is implemented in clinical practice, and current research points toward its use in oncology as opposed to incidental pulmonary nodule characterization. The most common complication of TNB is pneumothorax, and rates vary in series based on technique and study design. Two meta-analysis reported pooled rates of pneumothorax and hemoptysis of 19% to 25.3% and 4.1% to 12%, respectively [52,56]. Other studies report pneumothorax in 16% to 45% of cases and pneumothorax requiring a chest tube in 1.8% to 15% [52,53,56]. A meta-analysis of 46 studies from 2010-2015 described complication rates of CT-guided core-needle and FNA biopsy. They found that minor complications were more common in FNA, major complications were rare, and that smaller nodules, larger needle diameter, and increased transverse lung were risk factors for FNA complications. Complication rate for core biopsy was 38.8% versus 24.0% for FNA (P < . 001).
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Incidentally Detected Indeterminate Pulmonary Nodule PCAs. PET/MRI integrates anatomic and functional MRI data with the metabolic information of PET. Interest around PET/MRI includes functional information and higher soft-tissue contrast resolution. An international survey of active whole- body PET/MRI sites showed oncology as its main application. Perceived challenges to its widespread use included study duration (2 times longer than a typical PET/CT), lack of standardized protocols, and challenges with interpretation (>80% sites had radiologist and nuclear medicine physicians jointly reporting as opposed to 40% for PET/CT) [46]. When imaging the lungs, PET/MRI faces the same challenges as lung MRI. Small nonavid nodules are usually missed, and finding precise anatomic correlates for areas of lung uptake can be difficult. 9 Incidentally Detected Indeterminate Pulmonary Nodule 21.4% of the missed nodules were rated malignant. This resulted in one patient being upstaged from tumor stage I to IV [50]. Further advances on PET/MRI are needed before it is implemented in clinical practice, and current research points toward its use in oncology as opposed to incidental pulmonary nodule characterization. The most common complication of TNB is pneumothorax, and rates vary in series based on technique and study design. Two meta-analysis reported pooled rates of pneumothorax and hemoptysis of 19% to 25.3% and 4.1% to 12%, respectively [52,56]. Other studies report pneumothorax in 16% to 45% of cases and pneumothorax requiring a chest tube in 1.8% to 15% [52,53,56]. A meta-analysis of 46 studies from 2010-2015 described complication rates of CT-guided core-needle and FNA biopsy. They found that minor complications were more common in FNA, major complications were rare, and that smaller nodules, larger needle diameter, and increased transverse lung were risk factors for FNA complications. Complication rate for core biopsy was 38.8% versus 24.0% for FNA (P < . 001).
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Major complications were 5.7% and 4.4% for core biopsy and FNA, respectively (no statistical significance). Pooled complication rates for CT-guided core-needle biopsy included pneumothorax 25.3%, pneumothorax requiring intervention 5.6%, pulmonary hemorrhage 18.0%, and hemoptysis 4.1%. For FNA, complication rates were lower: 18.8%, 4.3%, 6.4%, and 1.7%, respectively [56]. A retrospective single-institution study of 550 patients found no statistical differences between pneumothorax rates between 18-G and 20-G CT-guided pulmonary nodule biopsies (25.6% versus 28.7%, respectively). Chest tube insertion rate for 18-G and 20-G was 4.8% versus 5.6%, 10 Incidentally Detected Indeterminate Pulmonary Nodule MRI Chest Without IV Contrast There is no relevant literature to support the use of MRI chest in the evaluation of incidentally detected indeterminate pulmonary nodules. MRI has been increasingly studied as an alternative method in the evaluation of incidental pulmonary nodules over the last decades, with reported sensitivities ranging from 26% to 96% for various MRI sequences [54]. Major limitations for accurate nodule characterization include artifact from respiratory and cardiac motion and poor image contrast in lung MRI. Motion artifact in pulmonary MRI results from longer sequence acquisition times compared to CT. Faster sequences and techniques have been studied to address this problem [57]. A small series by Heye et al [58] using a fast sequence reported a nodule detection rate of 45.5% compared to CT, along with a high number of false-positive nodules related to motion artifact. Nodule size is another well-known limiting factor for many MRI sequences. Overall, MRI might have a future role as a complementary tool in the stratification of incidental pulmonary nodules, possibly multiparametric MRI, but further research and validation studies are required before MRI is implemented in clinical practice.
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Incidentally Detected Indeterminate Pulmonary Nodule PCAs. Major complications were 5.7% and 4.4% for core biopsy and FNA, respectively (no statistical significance). Pooled complication rates for CT-guided core-needle biopsy included pneumothorax 25.3%, pneumothorax requiring intervention 5.6%, pulmonary hemorrhage 18.0%, and hemoptysis 4.1%. For FNA, complication rates were lower: 18.8%, 4.3%, 6.4%, and 1.7%, respectively [56]. A retrospective single-institution study of 550 patients found no statistical differences between pneumothorax rates between 18-G and 20-G CT-guided pulmonary nodule biopsies (25.6% versus 28.7%, respectively). Chest tube insertion rate for 18-G and 20-G was 4.8% versus 5.6%, 10 Incidentally Detected Indeterminate Pulmonary Nodule MRI Chest Without IV Contrast There is no relevant literature to support the use of MRI chest in the evaluation of incidentally detected indeterminate pulmonary nodules. MRI has been increasingly studied as an alternative method in the evaluation of incidental pulmonary nodules over the last decades, with reported sensitivities ranging from 26% to 96% for various MRI sequences [54]. Major limitations for accurate nodule characterization include artifact from respiratory and cardiac motion and poor image contrast in lung MRI. Motion artifact in pulmonary MRI results from longer sequence acquisition times compared to CT. Faster sequences and techniques have been studied to address this problem [57]. A small series by Heye et al [58] using a fast sequence reported a nodule detection rate of 45.5% compared to CT, along with a high number of false-positive nodules related to motion artifact. Nodule size is another well-known limiting factor for many MRI sequences. Overall, MRI might have a future role as a complementary tool in the stratification of incidental pulmonary nodules, possibly multiparametric MRI, but further research and validation studies are required before MRI is implemented in clinical practice.
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69455
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acrac_69455_10
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Incidentally Detected Indeterminate Pulmonary Nodule PCAs
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Current pulmonary nodule guidelines do not include MRI in the management algorithms for incidental pulmonary nodules [2,9]. MRI Chest Without and With IV Contrast There is no relevant literature to support the use of dynamic MRI chest in the evaluation of incidentally detected indeterminate pulmonary nodules. MRI has been increasingly studied as an alternative method in the evaluation of incidental pulmonary nodules over the last decades, with reported sensitivities ranging from 26% to 96% for various MRI sequences [54]. Major limitations for accurate nodule characterization include artifact from respiratory and cardiac motion and poor image contrast in lung MRI, which are addressed on the MRI Chest Without IV Contrast section. Similar to dynamic contrast-enhanced CT, dynamic MRI techniques have been proposed to differentiate benign from malignant pulmonary nodules. Reported sensitivities range from 52% to 100%, specificities from 17% to 100%, and accuracies from 58% to 96% [54,64]. Factors contributing to the wide ranges include variable study design, different sequences studied, and lower performance in cohorts living in areas with high prevalence of active infection. The authors have looked into improving the performance of dynamic contrast-enhanced MRI by adding semiquantitative analysis [65] or combining it with additional sequences, with a small series showing improved specificity and minimal improved accuracy in differentiating benign from malignant solitary nodules [54,66]. Incidentally Detected Indeterminate Pulmonary Nodule Overall, MRI might have a future role as a complementary tool in the stratification of incidental pulmonary nodules, possibly multiparametric MRI, but further research and validation studies are required before MRI is implemented in clinical practice. Current pulmonary nodule guidelines do not include MRI in the management algorithms for incidental pulmonary nodules [2,9].
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Incidentally Detected Indeterminate Pulmonary Nodule PCAs. Current pulmonary nodule guidelines do not include MRI in the management algorithms for incidental pulmonary nodules [2,9]. MRI Chest Without and With IV Contrast There is no relevant literature to support the use of dynamic MRI chest in the evaluation of incidentally detected indeterminate pulmonary nodules. MRI has been increasingly studied as an alternative method in the evaluation of incidental pulmonary nodules over the last decades, with reported sensitivities ranging from 26% to 96% for various MRI sequences [54]. Major limitations for accurate nodule characterization include artifact from respiratory and cardiac motion and poor image contrast in lung MRI, which are addressed on the MRI Chest Without IV Contrast section. Similar to dynamic contrast-enhanced CT, dynamic MRI techniques have been proposed to differentiate benign from malignant pulmonary nodules. Reported sensitivities range from 52% to 100%, specificities from 17% to 100%, and accuracies from 58% to 96% [54,64]. Factors contributing to the wide ranges include variable study design, different sequences studied, and lower performance in cohorts living in areas with high prevalence of active infection. The authors have looked into improving the performance of dynamic contrast-enhanced MRI by adding semiquantitative analysis [65] or combining it with additional sequences, with a small series showing improved specificity and minimal improved accuracy in differentiating benign from malignant solitary nodules [54,66]. Incidentally Detected Indeterminate Pulmonary Nodule Overall, MRI might have a future role as a complementary tool in the stratification of incidental pulmonary nodules, possibly multiparametric MRI, but further research and validation studies are required before MRI is implemented in clinical practice. Current pulmonary nodule guidelines do not include MRI in the management algorithms for incidental pulmonary nodules [2,9].
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69455
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acrac_69455_11
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Incidentally Detected Indeterminate Pulmonary Nodule PCAs
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Radiography Chest There is no relevant literature to support the use of chest radiographs in the evaluation or follow-up of incidentally detected indeterminate pulmonary nodules on chest CT. Radiograph sensitivity for detecting nodules is low, with a significant number of nodules missed [5]. Most nodules <1 cm are not visible in chest radiographs [9]. In addition, radiographs lack the resolution to adequately characterize nodules. Variant 4: Adult greater than or equal to 35 years of age. Incidentally detected indeterminate pulmonary nodule on incomplete thoracic CT (eg, CT abdomen, neck, spine, etc). Next imaging study. Lungs are partially seen on CT from other body parts including neck, spine, heart, and abdomen. Pulmonary nodules are frequently encountered on these studies and are described as the most common incidental finding by some authors [67-69]. Reported nodule incidence ranges from 8% to 23% for coronary CT angiography [7,69,70], 16.4% to 28.2% for patients undergoing CT for transcatheter aortic valve implantation [67,68,71], and 2.5% to 39.1% for abdominal CTs [72-74]. The most updated Fleischner Society guidelines address the management of nodules found on incomplete thoracic CT. Please refer to Appendix 3 for details. CT Chest Without and With IV Contrast There is no relevant literature to support the use of dynamic contrast-enhanced CT in the evaluation of incidentally detected indeterminate pulmonary nodules encountered on incomplete thoracic CT. Incidentally Detected Indeterminate Pulmonary Nodule CT Chest With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT in the evaluation of incidentally detected indeterminate pulmonary nodules encountered on incomplete thoracic CT. Cancer staging, an incidental mass workup, and nodules with associated lymphadenopathy fall outside of the scope of this document.
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Incidentally Detected Indeterminate Pulmonary Nodule PCAs. Radiography Chest There is no relevant literature to support the use of chest radiographs in the evaluation or follow-up of incidentally detected indeterminate pulmonary nodules on chest CT. Radiograph sensitivity for detecting nodules is low, with a significant number of nodules missed [5]. Most nodules <1 cm are not visible in chest radiographs [9]. In addition, radiographs lack the resolution to adequately characterize nodules. Variant 4: Adult greater than or equal to 35 years of age. Incidentally detected indeterminate pulmonary nodule on incomplete thoracic CT (eg, CT abdomen, neck, spine, etc). Next imaging study. Lungs are partially seen on CT from other body parts including neck, spine, heart, and abdomen. Pulmonary nodules are frequently encountered on these studies and are described as the most common incidental finding by some authors [67-69]. Reported nodule incidence ranges from 8% to 23% for coronary CT angiography [7,69,70], 16.4% to 28.2% for patients undergoing CT for transcatheter aortic valve implantation [67,68,71], and 2.5% to 39.1% for abdominal CTs [72-74]. The most updated Fleischner Society guidelines address the management of nodules found on incomplete thoracic CT. Please refer to Appendix 3 for details. CT Chest Without and With IV Contrast There is no relevant literature to support the use of dynamic contrast-enhanced CT in the evaluation of incidentally detected indeterminate pulmonary nodules encountered on incomplete thoracic CT. Incidentally Detected Indeterminate Pulmonary Nodule CT Chest With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT in the evaluation of incidentally detected indeterminate pulmonary nodules encountered on incomplete thoracic CT. Cancer staging, an incidental mass workup, and nodules with associated lymphadenopathy fall outside of the scope of this document.
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69455
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acrac_69338_0
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Sudden Onset of Cold Painful Leg
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Introduction/Background Acute onset of a cold, painful leg, also known as acute limb ischemia (ALI), describes the sudden loss of perfusion to the lower extremity and carries significant risk of morbidity and mortality. The pathophysiology primarily relates to acute arterial ischemia, in which there is often insufficient vascular collateralization to perfuse the lower extremity. A minority of cases may be related to a severe presentation of venous thrombotic disease. Known as phlegmasia cerulea dolens, this condition presents with lower extremity dusky discoloration, massive swelling, and pain. These clinical differences allow for differentiation from acute arterial ischemia. ALI requires rapid identification and treatment. The objectives of diagnostic imaging include confirmation of diagnosis, identifying the location and extent of vascular occlusion, and preprocedural/presurgical planning. The published literature regarding imaging of peripheral artery disease (PAD) focuses almost exclusively on patients with chronic PAD. This includes asymptomatic PAD, leg pain with exertion (ie, intermittent claudication), and critical limb ischemia (defined as chronic leg or foot pain at rest, skin ulceration, or gangrene). By comparison, the literature on imaging patients with ALI is very limited. Consequently, the following discussion relies heavily on studies of patients with chronic PAD. This document has separated imaging appropriateness based on the clinical scenario of suspected ALI for which signs and symptoms may include pain, pallor, paresthesia/paralysis, poikilothermia, and pulselessness, or more rarely with symptoms of phlegmasia cerulea dolens as described above, acknowledging that some patients may present with any combination of the above or other comorbidities that may require imaging. Additionally, compartment syndrome also induces acute ischemia via a separate mechanism of tissue pressurization within a fixed volume, often in the setting of trauma or other injury.
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Sudden Onset of Cold Painful Leg. Introduction/Background Acute onset of a cold, painful leg, also known as acute limb ischemia (ALI), describes the sudden loss of perfusion to the lower extremity and carries significant risk of morbidity and mortality. The pathophysiology primarily relates to acute arterial ischemia, in which there is often insufficient vascular collateralization to perfuse the lower extremity. A minority of cases may be related to a severe presentation of venous thrombotic disease. Known as phlegmasia cerulea dolens, this condition presents with lower extremity dusky discoloration, massive swelling, and pain. These clinical differences allow for differentiation from acute arterial ischemia. ALI requires rapid identification and treatment. The objectives of diagnostic imaging include confirmation of diagnosis, identifying the location and extent of vascular occlusion, and preprocedural/presurgical planning. The published literature regarding imaging of peripheral artery disease (PAD) focuses almost exclusively on patients with chronic PAD. This includes asymptomatic PAD, leg pain with exertion (ie, intermittent claudication), and critical limb ischemia (defined as chronic leg or foot pain at rest, skin ulceration, or gangrene). By comparison, the literature on imaging patients with ALI is very limited. Consequently, the following discussion relies heavily on studies of patients with chronic PAD. This document has separated imaging appropriateness based on the clinical scenario of suspected ALI for which signs and symptoms may include pain, pallor, paresthesia/paralysis, poikilothermia, and pulselessness, or more rarely with symptoms of phlegmasia cerulea dolens as described above, acknowledging that some patients may present with any combination of the above or other comorbidities that may require imaging. Additionally, compartment syndrome also induces acute ischemia via a separate mechanism of tissue pressurization within a fixed volume, often in the setting of trauma or other injury.
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acrac_69338_1
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Sudden Onset of Cold Painful Leg
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This entity may manifest overlapping symptomatology with ALI and should be excluded clinically before consideration of imaging modalities. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through representation of such organizations on expert panels. Participation on the expert panel does not necessarily imply endorsement of the final document by individual contributors or their respective organization. Reprint requests to: [email protected] Sudden Onset of Cold, Painful Leg Linear gadolinium-based agents used in contrast-enhanced MRI have previously been associated with nephrogenic systemic fibrosis (NSF) in patients with underlying renal dysfunction. However, in patients with acute kidney injury or stage 4/5 chronic kidney disease with current generation macrocyclic and linear agents (group II, ie, gadobenate dimeglumine, gadobutrol, gadoterate meglumine, gadoteridol, gadoxetic acid disodium) the risk of NSF is suggested to be so low that the potential harm of delaying or withholding contrast is likely to outweigh the risk of NSF in most clinical situations [5]. Group III agents (ie, gadoxetic acid disodium) have thus far demonstrated no unconfounded cases of NSF, although evidence is still limited. Of note, there is increasing evidence that gadolinium deposition occurs within the brain parenchyma, namely, within the dentate nuclei and globus pallidus, although with unknown clinical significance; this remains a topic of interest within MRI contrast safety [6]. Contrast-enhanced ultrasound (US) using microbubble-based intravenous (IV) contrast is being applied to a growing number of scenarios to demonstrate findings typically seen on contrast-enhanced CT and MRI. Early evidence has suggested the potential use of contrast-enhanced 3-D US to create targeted volumetric mapping of patent lower extremity arteries [7].
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Sudden Onset of Cold Painful Leg. This entity may manifest overlapping symptomatology with ALI and should be excluded clinically before consideration of imaging modalities. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through representation of such organizations on expert panels. Participation on the expert panel does not necessarily imply endorsement of the final document by individual contributors or their respective organization. Reprint requests to: [email protected] Sudden Onset of Cold, Painful Leg Linear gadolinium-based agents used in contrast-enhanced MRI have previously been associated with nephrogenic systemic fibrosis (NSF) in patients with underlying renal dysfunction. However, in patients with acute kidney injury or stage 4/5 chronic kidney disease with current generation macrocyclic and linear agents (group II, ie, gadobenate dimeglumine, gadobutrol, gadoterate meglumine, gadoteridol, gadoxetic acid disodium) the risk of NSF is suggested to be so low that the potential harm of delaying or withholding contrast is likely to outweigh the risk of NSF in most clinical situations [5]. Group III agents (ie, gadoxetic acid disodium) have thus far demonstrated no unconfounded cases of NSF, although evidence is still limited. Of note, there is increasing evidence that gadolinium deposition occurs within the brain parenchyma, namely, within the dentate nuclei and globus pallidus, although with unknown clinical significance; this remains a topic of interest within MRI contrast safety [6]. Contrast-enhanced ultrasound (US) using microbubble-based intravenous (IV) contrast is being applied to a growing number of scenarios to demonstrate findings typically seen on contrast-enhanced CT and MRI. Early evidence has suggested the potential use of contrast-enhanced 3-D US to create targeted volumetric mapping of patent lower extremity arteries [7].
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69338
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acrac_69338_2
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Sudden Onset of Cold Painful Leg
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Using CT angiography (CTA), novel techniques such as 3-D fluoroscopy-CT fusion software have demonstrated potential to augment intraprocedural arterial navigation [8]. Investigations into combined noncontrast CT and MR angiography (MRA) fusion have also been undertaken, combining the vessel wall detail of CT with the luminal detail of MRI in preprocedural vessel mapping [9]. However, evidence remains limited for these techniques in the diagnosis of ALI. All elements are essential: 1) timing, 2) reconstructions/reformats, and 3) 3-D renderings. Standard CTs with contrast also include timing issues and reconstructions/reformats. Only in CTA, however, is 3-D rendering a required element. This corresponds to the definitions that the CMS has applied to the Current Procedural Terminology codes. Sudden Onset of Cold, Painful Leg Discussion of Procedures by Variant Variant 1: Sudden onset of cold, painful leg. Suspected vascular compromise. Initial imaging. Arteriography Lower Extremity Catheter arteriography (digital subtraction angiography [DSA]) performed with iodinated contrast remains the definitive method for anatomic evaluation of lower extremity peripheral arterial disease, providing dynamic, time- resolved evaluation of vascular anatomy and vascular flow [11]. However, noninvasive cross-sectional angiography techniques (ie, CTA and MRA) are increasingly performed to confirm disease with a high degree of accuracy before the decision to catheterize and perform angiographic intervention [12-18]. Catheter arteriography is typically performed in the intraprocedural setting for interventional planning and imaging confirmation of therapeutic objectives [19,20]. The main disadvantages of arteriography are related to the invasive nature of the procedure, which imparts risks of vascular injury, infection, bleeding, and other complications [11,21], and which may require additional interventions and prolonged hospital stay.
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Sudden Onset of Cold Painful Leg. Using CT angiography (CTA), novel techniques such as 3-D fluoroscopy-CT fusion software have demonstrated potential to augment intraprocedural arterial navigation [8]. Investigations into combined noncontrast CT and MR angiography (MRA) fusion have also been undertaken, combining the vessel wall detail of CT with the luminal detail of MRI in preprocedural vessel mapping [9]. However, evidence remains limited for these techniques in the diagnosis of ALI. All elements are essential: 1) timing, 2) reconstructions/reformats, and 3) 3-D renderings. Standard CTs with contrast also include timing issues and reconstructions/reformats. Only in CTA, however, is 3-D rendering a required element. This corresponds to the definitions that the CMS has applied to the Current Procedural Terminology codes. Sudden Onset of Cold, Painful Leg Discussion of Procedures by Variant Variant 1: Sudden onset of cold, painful leg. Suspected vascular compromise. Initial imaging. Arteriography Lower Extremity Catheter arteriography (digital subtraction angiography [DSA]) performed with iodinated contrast remains the definitive method for anatomic evaluation of lower extremity peripheral arterial disease, providing dynamic, time- resolved evaluation of vascular anatomy and vascular flow [11]. However, noninvasive cross-sectional angiography techniques (ie, CTA and MRA) are increasingly performed to confirm disease with a high degree of accuracy before the decision to catheterize and perform angiographic intervention [12-18]. Catheter arteriography is typically performed in the intraprocedural setting for interventional planning and imaging confirmation of therapeutic objectives [19,20]. The main disadvantages of arteriography are related to the invasive nature of the procedure, which imparts risks of vascular injury, infection, bleeding, and other complications [11,21], and which may require additional interventions and prolonged hospital stay.
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69338
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acrac_69338_3
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Sudden Onset of Cold Painful Leg
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Arteriography has been criticized for its imperfect evaluation of outflow vessels, specifically for limited visualization of pedal vasculature and patent distal vessels beyond significant obstructive lesions [22]. Preprocedural examinations including duplex US, MRA, or CTA may provide useful information given these considerations and to inform preprocedural/presurgical planning [8]. CTA Abdomen and Pelvis with Bilateral Lower Extremity Runoff With IV Contrast CTA is useful in the diagnosis of ALI and peripheral arterial disease [12-18]. CTA in multiple meta-analyses has demonstrated sensitivity and specificity for detecting hemodynamically significant arterial stenosis of up to 96% and 96%, respectively, relative to DSA [15,18,23,24]. This cross-sectional imaging technique has several advantages over catheter arteriography via the manipulation of acquired imaging data, which includes thin axial, multiplanar, 3-D volume rendering, and maximum intensity projection reconstructions [25]. Additionally, poststenotic or postocclusive vascular anatomy and collateralization may be better demonstrated using CTA than by catheter arteriography. Compared to MRA, CTA demonstrates superior spatial resolution and shorter scan time, contributing to lower likelihood of motion degradation. CTA generally also is less susceptible to severe image degradation due to metal artifact. A major disadvantage of CTA is its limited ability to depict the lumen in heavily calcified arteries. Artifact induced by calcium can lead to an overestimation of stenosis [26]. Dual-energy CTA can be employed to reduce beam- hardening artifact from calcium or vascular stents [27,28]. CTA of the abdomen and pelvis can be obtained in addition to the lower extremity when aortoiliac disease is a concern or if the aorta and iliac arteries have not already been imaged and to assess for vascular suitability before endovascular intervention.
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Sudden Onset of Cold Painful Leg. Arteriography has been criticized for its imperfect evaluation of outflow vessels, specifically for limited visualization of pedal vasculature and patent distal vessels beyond significant obstructive lesions [22]. Preprocedural examinations including duplex US, MRA, or CTA may provide useful information given these considerations and to inform preprocedural/presurgical planning [8]. CTA Abdomen and Pelvis with Bilateral Lower Extremity Runoff With IV Contrast CTA is useful in the diagnosis of ALI and peripheral arterial disease [12-18]. CTA in multiple meta-analyses has demonstrated sensitivity and specificity for detecting hemodynamically significant arterial stenosis of up to 96% and 96%, respectively, relative to DSA [15,18,23,24]. This cross-sectional imaging technique has several advantages over catheter arteriography via the manipulation of acquired imaging data, which includes thin axial, multiplanar, 3-D volume rendering, and maximum intensity projection reconstructions [25]. Additionally, poststenotic or postocclusive vascular anatomy and collateralization may be better demonstrated using CTA than by catheter arteriography. Compared to MRA, CTA demonstrates superior spatial resolution and shorter scan time, contributing to lower likelihood of motion degradation. CTA generally also is less susceptible to severe image degradation due to metal artifact. A major disadvantage of CTA is its limited ability to depict the lumen in heavily calcified arteries. Artifact induced by calcium can lead to an overestimation of stenosis [26]. Dual-energy CTA can be employed to reduce beam- hardening artifact from calcium or vascular stents [27,28]. CTA of the abdomen and pelvis can be obtained in addition to the lower extremity when aortoiliac disease is a concern or if the aorta and iliac arteries have not already been imaged and to assess for vascular suitability before endovascular intervention.
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acrac_69338_4
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Sudden Onset of Cold Painful Leg
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CTA is considered the diagnostic reference standard over catheter angiography for aortic imaging [29,30]. CTA Lower Extremity with IV Contrast CTA is useful in the diagnosis of ALI and peripheral arterial disease [12-18]. CTA in multiple meta-analyses has demonstrated sensitivity and specificity for detecting hemodynamically significant arterial stenosis of up to 96% and 96%, respectively, relative to DSA [15,18,23,24]. This cross-sectional imaging technique has several advantages over catheter arteriography via the manipulation of acquired imaging data, including thin axial, 3-D volume rendering, and maximum intensity projection reconstructions [25]. Additionally, poststenotic or postocclusive vascular anatomy and collateralization may be better demonstrated using CTA than by catheter arteriography. Compared to MRA, CTA demonstrates superior spatial resolution and shorter scan time, contributing to lower likelihood of motion degradation. CTA generally also is less susceptible to severe image degradation due to metal artifact. A major disadvantage of CTA is its limited ability to depict the lumen in heavily calcified arteries. Artifact induced by calcium can lead to an overestimation of stenosis [26]. Dual-energy CTA can be employed to reduce beam- hardening artifact from calcium or vascular stents [27,28]. CTA of the abdomen and pelvis can be obtained in addition to the lower extremity when aortoiliac disease is a concern or if the aorta and iliac arteries have not already been imaged. The lack of visualization of the abdominal Sudden Onset of Cold, Painful Leg aorta and iliac vessels precludes evaluation for suitability before endovascular intervention or if pathology extends cranially beyond the lower extremities. MRA Abdomen and Pelvis with Bilateral Lower Extremity Runoff With IV Contrast The widespread adoption of 3T magnets has allowed for higher spatial resolution and signal-to-noise ratio acquisitions.
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Sudden Onset of Cold Painful Leg. CTA is considered the diagnostic reference standard over catheter angiography for aortic imaging [29,30]. CTA Lower Extremity with IV Contrast CTA is useful in the diagnosis of ALI and peripheral arterial disease [12-18]. CTA in multiple meta-analyses has demonstrated sensitivity and specificity for detecting hemodynamically significant arterial stenosis of up to 96% and 96%, respectively, relative to DSA [15,18,23,24]. This cross-sectional imaging technique has several advantages over catheter arteriography via the manipulation of acquired imaging data, including thin axial, 3-D volume rendering, and maximum intensity projection reconstructions [25]. Additionally, poststenotic or postocclusive vascular anatomy and collateralization may be better demonstrated using CTA than by catheter arteriography. Compared to MRA, CTA demonstrates superior spatial resolution and shorter scan time, contributing to lower likelihood of motion degradation. CTA generally also is less susceptible to severe image degradation due to metal artifact. A major disadvantage of CTA is its limited ability to depict the lumen in heavily calcified arteries. Artifact induced by calcium can lead to an overestimation of stenosis [26]. Dual-energy CTA can be employed to reduce beam- hardening artifact from calcium or vascular stents [27,28]. CTA of the abdomen and pelvis can be obtained in addition to the lower extremity when aortoiliac disease is a concern or if the aorta and iliac arteries have not already been imaged. The lack of visualization of the abdominal Sudden Onset of Cold, Painful Leg aorta and iliac vessels precludes evaluation for suitability before endovascular intervention or if pathology extends cranially beyond the lower extremities. MRA Abdomen and Pelvis with Bilateral Lower Extremity Runoff With IV Contrast The widespread adoption of 3T magnets has allowed for higher spatial resolution and signal-to-noise ratio acquisitions.
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acrac_69338_5
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Sudden Onset of Cold Painful Leg
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In multiple meta-analyses and prospective studies, contrast-enhanced MRA for the detection of hemodynamically significant arterial stenosis has yielded a sensitivity and specificity up to 97% and 96%, respectively, when compared to DSA [31-34]. Compared to CTA, MRA does not suffer from artifact related to calcium within small vessels. In addition, time- resolved sequences allow for dynamic visualization and separation of arterial and venous flow, allowing for increased diagnostic accuracy. In a study comparing to DSA, contrast-enhanced, time-resolved MRA at 3T with calf compression to prevent venous contamination demonstrated superior visualization of below-the-knee arterial vasculature than DSA [35]. Contrast-enhanced MRA may be an optimal imaging modality for patients at high risk for calcification of the distal arterial vessels, particularly patients with suspected significant arterial calcific plaque burden [16,36]. The imaging-related disadvantages of MRA include low signal-to-noise ratio, limited spatial resolution, longer acquisition times, and a greater potential for artifact-related image degradation, namely, from motion and susceptibility from metal stents and orthopedic hardware; techniques have been developed to address some of these issues [37-40]. Safety risks inherent to MRI should also be considered, such as magnetic field bioeffects. MRA of the abdomen and pelvis can be obtained in addition to bilateral lower extremity runoff when aortoiliac disease is a concern or if the aorta and iliac arteries have not already been imaged and to assess for vascular suitability before endovascular intervention. MRA Abdomen and Pelvis with Bilateral Lower Extremity Runoff Without IV Contrast Noncontrast MRA techniques have been in use for decades in the form of 2-D and 3-D time-of-flight. However, noncontrast MRA is rarely used in the setting of PAD or ALI because of long acquisition times relative to contrast- enhanced MRA and CTA.
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Sudden Onset of Cold Painful Leg. In multiple meta-analyses and prospective studies, contrast-enhanced MRA for the detection of hemodynamically significant arterial stenosis has yielded a sensitivity and specificity up to 97% and 96%, respectively, when compared to DSA [31-34]. Compared to CTA, MRA does not suffer from artifact related to calcium within small vessels. In addition, time- resolved sequences allow for dynamic visualization and separation of arterial and venous flow, allowing for increased diagnostic accuracy. In a study comparing to DSA, contrast-enhanced, time-resolved MRA at 3T with calf compression to prevent venous contamination demonstrated superior visualization of below-the-knee arterial vasculature than DSA [35]. Contrast-enhanced MRA may be an optimal imaging modality for patients at high risk for calcification of the distal arterial vessels, particularly patients with suspected significant arterial calcific plaque burden [16,36]. The imaging-related disadvantages of MRA include low signal-to-noise ratio, limited spatial resolution, longer acquisition times, and a greater potential for artifact-related image degradation, namely, from motion and susceptibility from metal stents and orthopedic hardware; techniques have been developed to address some of these issues [37-40]. Safety risks inherent to MRI should also be considered, such as magnetic field bioeffects. MRA of the abdomen and pelvis can be obtained in addition to bilateral lower extremity runoff when aortoiliac disease is a concern or if the aorta and iliac arteries have not already been imaged and to assess for vascular suitability before endovascular intervention. MRA Abdomen and Pelvis with Bilateral Lower Extremity Runoff Without IV Contrast Noncontrast MRA techniques have been in use for decades in the form of 2-D and 3-D time-of-flight. However, noncontrast MRA is rarely used in the setting of PAD or ALI because of long acquisition times relative to contrast- enhanced MRA and CTA.
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acrac_69338_6
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Sudden Onset of Cold Painful Leg
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However, hardware advances and faster, novel sequences such as quiescent interval slice- selective MRA and flow-sensitive dephasing have demonstrated comparable diagnostic accuracies to contrast- enhanced MRA in the evaluation of PAD in multiple prospective studies and trials [41-43]. The imaging-related disadvantages of MRA relative to CTA include lower signal-to-noise ratio, limited spatial resolution, longer acquisition times, and a greater potential for artifact-related image degradation, namely, from motion and susceptibility from metal stents and orthopedic hardware; techniques have been developed to address some of these issues [37-40]. MRA of the abdomen and pelvis can be obtained in addition to bilateral lower extremity runoff when aortoiliac disease is a concern or if the aorta and iliac arteries have not already been imaged and to assess for vascular suitability for endovascular intervention. MRA Lower Extremity Without and With IV Contrast The widespread adoption of 3T magnets has allowed for higher spatial resolution and signal-to-noise ratio acquisitions. In multiple meta-analyses and prospective studies, contrast-enhanced MRA for the detection of hemodynamically significant arterial stenosis has yielded a sensitivity and specificity up to 97% and 96%, respectively, when compared to DSA [31-34]. Compared to CTA, MRA does not suffer from artifact related to calcium within small vessels. In addition, time- resolved sequences allow for dynamic visualization and separation of arterial and venous flow, allowing for increased diagnostic accuracy. In a study comparing to DSA, contrast-enhanced, time-resolved MRA at 3T with calf compression to prevent venous contamination demonstrated superior visualization of below-the-knee arterial vasculature than DSA [35].
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Sudden Onset of Cold Painful Leg. However, hardware advances and faster, novel sequences such as quiescent interval slice- selective MRA and flow-sensitive dephasing have demonstrated comparable diagnostic accuracies to contrast- enhanced MRA in the evaluation of PAD in multiple prospective studies and trials [41-43]. The imaging-related disadvantages of MRA relative to CTA include lower signal-to-noise ratio, limited spatial resolution, longer acquisition times, and a greater potential for artifact-related image degradation, namely, from motion and susceptibility from metal stents and orthopedic hardware; techniques have been developed to address some of these issues [37-40]. MRA of the abdomen and pelvis can be obtained in addition to bilateral lower extremity runoff when aortoiliac disease is a concern or if the aorta and iliac arteries have not already been imaged and to assess for vascular suitability for endovascular intervention. MRA Lower Extremity Without and With IV Contrast The widespread adoption of 3T magnets has allowed for higher spatial resolution and signal-to-noise ratio acquisitions. In multiple meta-analyses and prospective studies, contrast-enhanced MRA for the detection of hemodynamically significant arterial stenosis has yielded a sensitivity and specificity up to 97% and 96%, respectively, when compared to DSA [31-34]. Compared to CTA, MRA does not suffer from artifact related to calcium within small vessels. In addition, time- resolved sequences allow for dynamic visualization and separation of arterial and venous flow, allowing for increased diagnostic accuracy. In a study comparing to DSA, contrast-enhanced, time-resolved MRA at 3T with calf compression to prevent venous contamination demonstrated superior visualization of below-the-knee arterial vasculature than DSA [35].
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acrac_69338_7
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Sudden Onset of Cold Painful Leg
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Contrast-enhanced MRA may be an optimal imaging modality for patients at high risk for calcification of the distal arterial vessels, particularly patients with suspected significant arterial calcific plaque burden [16,36]. The imaging-related disadvantages of MRA relative to CTA include lower signal-to-noise ratio, limited spatial resolution, longer acquisition times, and a greater potential for artifact-related image degradation, namely, from motion and susceptibility from metal stents and orthopedic hardware; techniques have been developed to address some of these issues [37-40]. Sudden Onset of Cold, Painful Leg MRA of the abdomen and pelvis can be obtained in addition to bilateral lower extremity runoff when aortoiliac disease is a concern or if the aorta and iliac arteries have not already been imaged. The lack of visualization of the abdominal aorta and iliac vessels precludes evaluation for suitability before endovascular intervention or if pathology extends cranially beyond the lower extremities. MRA Lower Extremity Without IV Contrast The imaging-related disadvantages of MRA relative to CTA include lower signal-to-noise ratio, limited spatial resolution, longer acquisition times, and a greater potential for artifact-related image degradation, namely, from motion and susceptibility from metal stents and orthopedic hardware; numerous techniques have been developed to address some of these issues [37-40]. Compared to MRA abdomen and pelvis with bilateral lower extremity runoff without IV contrast, the lack of visualization of the abdominal aorta and iliac vessels precludes evaluation for suitability for possible endovascular intervention or if pathology extends cranially beyond the lower extremities. US Duplex Doppler Aorta Abdomen Duplex Doppler US is a noninvasive, portable imaging modality that can be quickly performed and repeated without potential risk.
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Sudden Onset of Cold Painful Leg. Contrast-enhanced MRA may be an optimal imaging modality for patients at high risk for calcification of the distal arterial vessels, particularly patients with suspected significant arterial calcific plaque burden [16,36]. The imaging-related disadvantages of MRA relative to CTA include lower signal-to-noise ratio, limited spatial resolution, longer acquisition times, and a greater potential for artifact-related image degradation, namely, from motion and susceptibility from metal stents and orthopedic hardware; techniques have been developed to address some of these issues [37-40]. Sudden Onset of Cold, Painful Leg MRA of the abdomen and pelvis can be obtained in addition to bilateral lower extremity runoff when aortoiliac disease is a concern or if the aorta and iliac arteries have not already been imaged. The lack of visualization of the abdominal aorta and iliac vessels precludes evaluation for suitability before endovascular intervention or if pathology extends cranially beyond the lower extremities. MRA Lower Extremity Without IV Contrast The imaging-related disadvantages of MRA relative to CTA include lower signal-to-noise ratio, limited spatial resolution, longer acquisition times, and a greater potential for artifact-related image degradation, namely, from motion and susceptibility from metal stents and orthopedic hardware; numerous techniques have been developed to address some of these issues [37-40]. Compared to MRA abdomen and pelvis with bilateral lower extremity runoff without IV contrast, the lack of visualization of the abdominal aorta and iliac vessels precludes evaluation for suitability for possible endovascular intervention or if pathology extends cranially beyond the lower extremities. US Duplex Doppler Aorta Abdomen Duplex Doppler US is a noninvasive, portable imaging modality that can be quickly performed and repeated without potential risk.
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acrac_3188532_0
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Fibroids
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Introduction/Background Uterine fibroids (leiomyomas or myomas) are the most common neoplasm of the uterus. They are composed of benign smooth muscle cells embedded in an extracellular matrix of collagen, fibronectin, and proteoglycan [1]. The prevalence of fibroids varies with race. Black women have an estimated incidence of fibroids by age 50 exceeding 80%, whereas White women have an incidence approaching 70% [2]. Although incompletely understood, fibroid etiology is multifactorial. A combination of genetic alterations and endocrine, autocrine, environmental, and other factors such as race, age, parity, and body mass index all play a role in fibroid development. Black women are more likely to develop clinically significant disease at an earlier age and are subject to racial disparities, including higher rates of surgical intervention when compared with medical therapy, as well as lower rates of minimally invasive approaches [3-6]. Fibroid-associated symptoms peak in the perimenopausal years and decline after menopause. Menorrhagia is the most frequent symptom and often results in iron deficiency anemia. Other common symptoms include dysmenorrhea, pelvic pain and pressure, urinary urgency and frequency, and constipation. Fibroids may also impair fertility and/or cause obstetric complications [7]. Despite the high prevalence and protean symptoms, there are few randomized trials to guide therapy. Patient preferences and symptom severity help inform treatment choice with options ranging from medical therapy to surgery. Hysterectomy is curative. One-half to one-third of the approximately 600,000 hysterectomies performed annually in the United States are for symptomatic fibroids [1,4]. Uterine sparing therapies include medical therapy (eg, GnRH agonists, levonorgestrel-releasing intrauterine devices, contraceptive steroid hormones, and tranexamic acid), myomectomy, endometrial ablation, uterine fibroid embolization (UFE), MR-guided focused ultrasound (MRgFUS), and laparoscopic radiofrequency ablation.
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Fibroids. Introduction/Background Uterine fibroids (leiomyomas or myomas) are the most common neoplasm of the uterus. They are composed of benign smooth muscle cells embedded in an extracellular matrix of collagen, fibronectin, and proteoglycan [1]. The prevalence of fibroids varies with race. Black women have an estimated incidence of fibroids by age 50 exceeding 80%, whereas White women have an incidence approaching 70% [2]. Although incompletely understood, fibroid etiology is multifactorial. A combination of genetic alterations and endocrine, autocrine, environmental, and other factors such as race, age, parity, and body mass index all play a role in fibroid development. Black women are more likely to develop clinically significant disease at an earlier age and are subject to racial disparities, including higher rates of surgical intervention when compared with medical therapy, as well as lower rates of minimally invasive approaches [3-6]. Fibroid-associated symptoms peak in the perimenopausal years and decline after menopause. Menorrhagia is the most frequent symptom and often results in iron deficiency anemia. Other common symptoms include dysmenorrhea, pelvic pain and pressure, urinary urgency and frequency, and constipation. Fibroids may also impair fertility and/or cause obstetric complications [7]. Despite the high prevalence and protean symptoms, there are few randomized trials to guide therapy. Patient preferences and symptom severity help inform treatment choice with options ranging from medical therapy to surgery. Hysterectomy is curative. One-half to one-third of the approximately 600,000 hysterectomies performed annually in the United States are for symptomatic fibroids [1,4]. Uterine sparing therapies include medical therapy (eg, GnRH agonists, levonorgestrel-releasing intrauterine devices, contraceptive steroid hormones, and tranexamic acid), myomectomy, endometrial ablation, uterine fibroid embolization (UFE), MR-guided focused ultrasound (MRgFUS), and laparoscopic radiofrequency ablation.
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acrac_3188532_1
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Fibroids
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Of these, myomectomy and UFE are the most common, and in a recent multicenter, randomized, open-label trial comparing myomectomy to UFE, both therapies resulted in equivalent symptomatic improvement at 2 years [8]. Special Imaging Considerations Saline infusion sonohysterography (SIS), a minimally invasive procedure distending the endometrial cavity with saline, enables better delineation between endometrial pathologies (polyps, hyperplasia, synechiae, etc) and submucosal fibroids. Studies have shown an overall good agreement (kappa 0.80) between 3-D SIS and diagnostic hysteroscopy to classify submucosal fibroids [9,10]. SIS has also been shown to accurately depict the percentage intracavitary component of submucosal fibroids, a finding that often has treatment implications [11,12]. Three-dimensional transvaginal ultrasound (3-D TVUS) is a reconstruction of the US volumetric data into high- resolution multiplanar imaging, including real-time surface rendered images [13]. In initial assessment, 3-D US has been used along with 2-D US for uterine pathologies, mostly submucosal fibroids, and endometrial polyps. A study of 139 cases comparing 3-D US against hysteroscopy in diagnosing uterine cavity abnormalities showed a sensitivity and specificity of 87% and 100% in diagnosing submucosal leiomyoma [14]. However, another study showed no significant advantage of 3-D US over 2-D US in estimating intracavitary protrusion of submucosal Reprint requests to: [email protected] Fibroids fibroid with a reference standard of hysteroscopy and a moderate interobserver agreement of 3-D US for submucosal fibroid [15]. US elastography/sonoelastography is a technique that measures tissue strain. Strain elastography used with routine TVUS has shown increased diagnostic accuracy in identifying myometrial pathologies (fibroids and adenomyosis) from normal myometrium [16,17].
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Fibroids. Of these, myomectomy and UFE are the most common, and in a recent multicenter, randomized, open-label trial comparing myomectomy to UFE, both therapies resulted in equivalent symptomatic improvement at 2 years [8]. Special Imaging Considerations Saline infusion sonohysterography (SIS), a minimally invasive procedure distending the endometrial cavity with saline, enables better delineation between endometrial pathologies (polyps, hyperplasia, synechiae, etc) and submucosal fibroids. Studies have shown an overall good agreement (kappa 0.80) between 3-D SIS and diagnostic hysteroscopy to classify submucosal fibroids [9,10]. SIS has also been shown to accurately depict the percentage intracavitary component of submucosal fibroids, a finding that often has treatment implications [11,12]. Three-dimensional transvaginal ultrasound (3-D TVUS) is a reconstruction of the US volumetric data into high- resolution multiplanar imaging, including real-time surface rendered images [13]. In initial assessment, 3-D US has been used along with 2-D US for uterine pathologies, mostly submucosal fibroids, and endometrial polyps. A study of 139 cases comparing 3-D US against hysteroscopy in diagnosing uterine cavity abnormalities showed a sensitivity and specificity of 87% and 100% in diagnosing submucosal leiomyoma [14]. However, another study showed no significant advantage of 3-D US over 2-D US in estimating intracavitary protrusion of submucosal Reprint requests to: [email protected] Fibroids fibroid with a reference standard of hysteroscopy and a moderate interobserver agreement of 3-D US for submucosal fibroid [15]. US elastography/sonoelastography is a technique that measures tissue strain. Strain elastography used with routine TVUS has shown increased diagnostic accuracy in identifying myometrial pathologies (fibroids and adenomyosis) from normal myometrium [16,17].
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3188532
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acrac_3188532_2
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Fibroids
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On sonoelastography, foci of adenomyosis are seen as brighter irregular shaped lesions (because of the presence of endometrial glands and stroma implanted within the myometrium), whereas fibroids are seen as well-delineated dark areas (secondary to stiffer/compressed smooth muscle fibers) [18,19]. Compression sonoelastography is a method of applying gentle compression causing alteration in size and shape of the lesion based on the tissue stiffness, which can be qualitatively (as a color map) or quantitatively recorded. Studies have shown high interobserver and intermethod agreement for the measurement of uterine and fibroid volumes on compression elastography [19] and excellent agreement between elastography-based diagnosis of fibroids and adenomyosis with MRI-based diagnosis [18]. The role of artificial intelligence in imaging fibroids is currently under investigation. There are several studies evaluating machine learning with textural analysis to improve the diagnostic accuracy of differentiating fibroids from sarcomas [20]. OR Discussion of Procedures by Variant Variant 1: Clinically suspected fibroids. Initial imaging. CT Pelvis There is no relevant literature to support the use of pelvic CT without or with intravenous (IV) contrast as initial imaging modality for clinically suspected fibroids. MRI Pelvis MRI excels at identifying and mapping fibroids [21-25]. When MRI is clinically useful, the use of a gadolinium- based IV contrast agent is preferred for identification of fibroid vascularity and other characteristics [26]. Please see the ACR Manual on Contrast Media for additional information [27]. Signal intensity and contrast enhancement allow diagnosis of fibroids to include size, number and location, and assessment of vascularity and to help characterize them as classic, degenerated (hyaline, carneous, hydropic, fatty, cystic, and myxoid), cellular, or atypical [28-30].
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Fibroids. On sonoelastography, foci of adenomyosis are seen as brighter irregular shaped lesions (because of the presence of endometrial glands and stroma implanted within the myometrium), whereas fibroids are seen as well-delineated dark areas (secondary to stiffer/compressed smooth muscle fibers) [18,19]. Compression sonoelastography is a method of applying gentle compression causing alteration in size and shape of the lesion based on the tissue stiffness, which can be qualitatively (as a color map) or quantitatively recorded. Studies have shown high interobserver and intermethod agreement for the measurement of uterine and fibroid volumes on compression elastography [19] and excellent agreement between elastography-based diagnosis of fibroids and adenomyosis with MRI-based diagnosis [18]. The role of artificial intelligence in imaging fibroids is currently under investigation. There are several studies evaluating machine learning with textural analysis to improve the diagnostic accuracy of differentiating fibroids from sarcomas [20]. OR Discussion of Procedures by Variant Variant 1: Clinically suspected fibroids. Initial imaging. CT Pelvis There is no relevant literature to support the use of pelvic CT without or with intravenous (IV) contrast as initial imaging modality for clinically suspected fibroids. MRI Pelvis MRI excels at identifying and mapping fibroids [21-25]. When MRI is clinically useful, the use of a gadolinium- based IV contrast agent is preferred for identification of fibroid vascularity and other characteristics [26]. Please see the ACR Manual on Contrast Media for additional information [27]. Signal intensity and contrast enhancement allow diagnosis of fibroids to include size, number and location, and assessment of vascularity and to help characterize them as classic, degenerated (hyaline, carneous, hydropic, fatty, cystic, and myxoid), cellular, or atypical [28-30].
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3188532
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acrac_3188532_3
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Fibroids
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Conventional MRI, however, cannot accurately differentiate fibroids from sarcomas, a critical distinction for surgical planning and optimizing outcomes [31-33]. Diffusion- weighted imaging with apparent diffusion coefficient (ADC), especially when incorporated into an MRI algorithm, has shown promising results in distinguishing the two entities [20,34-40]. In a large, case-controlled retrospective study of women with atypical uterine masses, a diagnostic algorithm based on enlarged lymph nodes, peritoneal implants, high diffusion MRI signal, and low ADC values was developed and validated. The resulting algorithm achieved a 98% sensitivity and a 96% specificity in the training set and 83% to 88% sensitivity and 97% to 100% specificity in the validation sets [34]. Machine learning with texture analysis is under investigation and may have the potential to improve diagnostic accuracy [20]. MRI can differentiate fibroids from alternative or comorbid conditions such as adenomyosis and endometriosis that often cause similar symptoms [41,42]. US Pelvis Transabdominal A combination of transabdominal US (TAUS) and TVUS of the pelvis is the most useful modality in the initial evaluation of suspected uterine fibroid or abnormal uterine bleeding [43-45]. TAUS is often useful in significantly Fibroids enlarged fibroid uterus or large subserosal/pedunculated fibroids that may render poor visualization on TVUS because of limited field-of-view from poor acoustic penetration. A potential limitation of TAUS is the poor acoustic window from decompressed urinary bladder, retroverted uterus, large body habitus, and bowel gas [46]. US Pelvis Transvaginal TVUS provides higher contrast and spatial resolution and should be combined with the TAUS whenever possible to evaluate suspected uterine fibroid [46,47]. TVUS has a reported sensitivity of 90% to 99% for detecting uterine fibroids and a sensitivity of 90% and specificity of 98% for the diagnosis of submucosal fibroids [43,48,49].
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Fibroids. Conventional MRI, however, cannot accurately differentiate fibroids from sarcomas, a critical distinction for surgical planning and optimizing outcomes [31-33]. Diffusion- weighted imaging with apparent diffusion coefficient (ADC), especially when incorporated into an MRI algorithm, has shown promising results in distinguishing the two entities [20,34-40]. In a large, case-controlled retrospective study of women with atypical uterine masses, a diagnostic algorithm based on enlarged lymph nodes, peritoneal implants, high diffusion MRI signal, and low ADC values was developed and validated. The resulting algorithm achieved a 98% sensitivity and a 96% specificity in the training set and 83% to 88% sensitivity and 97% to 100% specificity in the validation sets [34]. Machine learning with texture analysis is under investigation and may have the potential to improve diagnostic accuracy [20]. MRI can differentiate fibroids from alternative or comorbid conditions such as adenomyosis and endometriosis that often cause similar symptoms [41,42]. US Pelvis Transabdominal A combination of transabdominal US (TAUS) and TVUS of the pelvis is the most useful modality in the initial evaluation of suspected uterine fibroid or abnormal uterine bleeding [43-45]. TAUS is often useful in significantly Fibroids enlarged fibroid uterus or large subserosal/pedunculated fibroids that may render poor visualization on TVUS because of limited field-of-view from poor acoustic penetration. A potential limitation of TAUS is the poor acoustic window from decompressed urinary bladder, retroverted uterus, large body habitus, and bowel gas [46]. US Pelvis Transvaginal TVUS provides higher contrast and spatial resolution and should be combined with the TAUS whenever possible to evaluate suspected uterine fibroid [46,47]. TVUS has a reported sensitivity of 90% to 99% for detecting uterine fibroids and a sensitivity of 90% and specificity of 98% for the diagnosis of submucosal fibroids [43,48,49].
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3188532
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acrac_3188532_4
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Fibroids
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Three- dimensional TAUS and TVUS along with Doppler has shown high accuracy in differentiating uterine fibroids from adenomyosis with a sensitivity, specificity, and negative predictive value of 93%, 96%, and 88% for fibroids and 96%, 93%, and 98% for adenomyosis [50]. In a meta-analysis by Bittencourt et al [51], the pooled sensitivity and specificity of 2-D TVUS with SIS in diagnosing submucosal fibroids was 94% and 81%, respectively. The limitations of TVUS are a limited depth of penetration and a shallow focal length that can limit the evaluation of large or subserosal/pedunculated fibroids. US Duplex Doppler Pelvis Although Doppler imaging is labeled under separate imaging procedure per ACR methodology, this document considers it to be a standard component of pelvic US. Color Doppler is routinely used in pelvic US examinations to evaluate internal vascularity of pelvic/uterine findings and to differentiate between vascular and nonvascular tissue [47]. US duplex Doppler evaluation may also help in differentiating submucosal/intracavitary fibroids from endometrial polyps. Visualization of a vascular pedicle on transvaginal color Doppler imaging has a specificity of 95% to 98% and a negative predictive value of 81% to 94% for the detection of endometrial polyps [57,58]. Variant 2: Known fibroids. Treatment planning. Initial imaging. CT Pelvis There is no relevant literature to support the use of pelvic CT without or with IV contrast as initial imaging in treatment planning for symptomatic fibroids. CT, however, can better delineate calcified fibroids relative to US and MRI that may have treatment implications. MRI Pelvis MRI is superior to US (transabdominal followed by transvaginal) for identifying and mapping fibroids and may alter management in up to 28% of patients [22-25,59-61]. When MRI is clinically useful, the use of a gadolinium- based IV contrast agent is preferred [26]. Please see the ACR Manual on Contrast Media for additional information [27].
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Fibroids. Three- dimensional TAUS and TVUS along with Doppler has shown high accuracy in differentiating uterine fibroids from adenomyosis with a sensitivity, specificity, and negative predictive value of 93%, 96%, and 88% for fibroids and 96%, 93%, and 98% for adenomyosis [50]. In a meta-analysis by Bittencourt et al [51], the pooled sensitivity and specificity of 2-D TVUS with SIS in diagnosing submucosal fibroids was 94% and 81%, respectively. The limitations of TVUS are a limited depth of penetration and a shallow focal length that can limit the evaluation of large or subserosal/pedunculated fibroids. US Duplex Doppler Pelvis Although Doppler imaging is labeled under separate imaging procedure per ACR methodology, this document considers it to be a standard component of pelvic US. Color Doppler is routinely used in pelvic US examinations to evaluate internal vascularity of pelvic/uterine findings and to differentiate between vascular and nonvascular tissue [47]. US duplex Doppler evaluation may also help in differentiating submucosal/intracavitary fibroids from endometrial polyps. Visualization of a vascular pedicle on transvaginal color Doppler imaging has a specificity of 95% to 98% and a negative predictive value of 81% to 94% for the detection of endometrial polyps [57,58]. Variant 2: Known fibroids. Treatment planning. Initial imaging. CT Pelvis There is no relevant literature to support the use of pelvic CT without or with IV contrast as initial imaging in treatment planning for symptomatic fibroids. CT, however, can better delineate calcified fibroids relative to US and MRI that may have treatment implications. MRI Pelvis MRI is superior to US (transabdominal followed by transvaginal) for identifying and mapping fibroids and may alter management in up to 28% of patients [22-25,59-61]. When MRI is clinically useful, the use of a gadolinium- based IV contrast agent is preferred [26]. Please see the ACR Manual on Contrast Media for additional information [27].
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3188532
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acrac_3188532_5
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Fibroids
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Fibroid location, volume, number, T1- and T2-weighted signal intensity, and enhancement provide important pretreatment information [25,62-65]. Intracavitary fibroids may be amenable to hysteroscopic resection, whereas submucosal, intramural, and broad-based subserosal fibroids are amenable to UFE. Cervical fibroids may not respond as well or have a durable response to embolization. Submucosal and intramural fibroids that contact the endometrium may be expelled following successful UFE in 2.2% to 7.7% of cases [1,25,66]. Pedunculated fibroids, depending on location and stalk caliber, may be treated hysteroscopically, laparoscopically, or with UFE [25]. Postcontrast imaging allows assessment of fibroid viability, uterine artery anatomy, and detection of ovarian arterial collateral supply to the uterus [67-71]. Nonviable/autoinfarcted fibroids, found in up to 20% of UFE candidates, do not respond to UFE and are therefore important to identify at time of treatment planning [71]. A meta-analysis on the utility of ADC values concluded that, because of heterogeneity, it is unclear whether ADC values are useful to predict UFE response [72]. Conventional MRI, however, cannot accurately differentiate fibroids from sarcomas, a critical distinction for surgical planning and optimizing outcomes [31-33]. Diffusion-weighted imaging with ADC, especially when Fibroids incorporated into an MRI algorithm, has shown promising results in distinguishing the two entities [20,34-40]. In a large, case-controlled retrospective study of women with atypical uterine masses, a diagnostic algorithm based on enlarged lymph nodes, peritoneal implants, high diffusion MRI signal, and low ADC values was developed and validated. The resulting algorithm achieved a 98% sensitivity and a 96% specificity in the training set and 83% to 88% sensitivity and 97% to 100% specificity in the validation sets [34]. Machine learning with texture analysis is under investigation and may have the potential to improve diagnostic accuracy [20].
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Fibroids. Fibroid location, volume, number, T1- and T2-weighted signal intensity, and enhancement provide important pretreatment information [25,62-65]. Intracavitary fibroids may be amenable to hysteroscopic resection, whereas submucosal, intramural, and broad-based subserosal fibroids are amenable to UFE. Cervical fibroids may not respond as well or have a durable response to embolization. Submucosal and intramural fibroids that contact the endometrium may be expelled following successful UFE in 2.2% to 7.7% of cases [1,25,66]. Pedunculated fibroids, depending on location and stalk caliber, may be treated hysteroscopically, laparoscopically, or with UFE [25]. Postcontrast imaging allows assessment of fibroid viability, uterine artery anatomy, and detection of ovarian arterial collateral supply to the uterus [67-71]. Nonviable/autoinfarcted fibroids, found in up to 20% of UFE candidates, do not respond to UFE and are therefore important to identify at time of treatment planning [71]. A meta-analysis on the utility of ADC values concluded that, because of heterogeneity, it is unclear whether ADC values are useful to predict UFE response [72]. Conventional MRI, however, cannot accurately differentiate fibroids from sarcomas, a critical distinction for surgical planning and optimizing outcomes [31-33]. Diffusion-weighted imaging with ADC, especially when Fibroids incorporated into an MRI algorithm, has shown promising results in distinguishing the two entities [20,34-40]. In a large, case-controlled retrospective study of women with atypical uterine masses, a diagnostic algorithm based on enlarged lymph nodes, peritoneal implants, high diffusion MRI signal, and low ADC values was developed and validated. The resulting algorithm achieved a 98% sensitivity and a 96% specificity in the training set and 83% to 88% sensitivity and 97% to 100% specificity in the validation sets [34]. Machine learning with texture analysis is under investigation and may have the potential to improve diagnostic accuracy [20].
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3188532
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acrac_3188532_6
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Fibroids
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For patients undergoing MRgFUS, prediction models and multivariate analyses have found that nonperfused volume, a surrogate of symptom improvement, is a function of fibroid signal intensity, peak and time to peak enhancement, subcutaneous fat thickness, and distance from spine. A nonperfused volume >80% predicted clinical success in more than 80% of patients [73-76]. US Pelvis Transabdominal A combination of TAUS and TVUS of the pelvis is a frequently used imaging modality in pretreatment evaluation of known uterine fibroids [77,78]. TAUS is often useful in significantly enlarged fibroid uterus or large subserosal/pedunculated fibroids that may render poor visualization on TVUS because of limited field-of-view from poor acoustic penetration. A limitation of TAUS is a poor acoustic window from decompressed urinary bladder, retroverted uterus, large body habitus, and bowel gas [46]. US Pelvis Transvaginal TVUS provides higher contrast and spatial resolution and should be combined with the TAUS whenever possible to evaluate suspected uterine fibroid [46,47]. TVUS has a reported sensitivity of 90% to 99% for detecting uterine fibroids and a sensitivity of 90% and specificity of 98% for the diagnosis of submucosal fibroids [43,48,49]. The limitations of TVUS are a limited depth of penetration and a shallow focal length that can limit the evaluation of large or subserosal/pedunculated fibroids. The presence of numerous fibroids may also pose challenge in clearly delineating and precisely measuring the fibroids because of too poor an acoustic window. US Duplex Doppler Pelvis Although Doppler imaging is labeled under separate imaging procedure per ACR methodology, this document considers it to be a standard component of pelvic US. Color and spectral Doppler are routinely used in pelvic US examinations to evaluate internal vascularity of pelvic/uterine findings and to differentiate between vascular and nonvascular tissue [47].
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Fibroids. For patients undergoing MRgFUS, prediction models and multivariate analyses have found that nonperfused volume, a surrogate of symptom improvement, is a function of fibroid signal intensity, peak and time to peak enhancement, subcutaneous fat thickness, and distance from spine. A nonperfused volume >80% predicted clinical success in more than 80% of patients [73-76]. US Pelvis Transabdominal A combination of TAUS and TVUS of the pelvis is a frequently used imaging modality in pretreatment evaluation of known uterine fibroids [77,78]. TAUS is often useful in significantly enlarged fibroid uterus or large subserosal/pedunculated fibroids that may render poor visualization on TVUS because of limited field-of-view from poor acoustic penetration. A limitation of TAUS is a poor acoustic window from decompressed urinary bladder, retroverted uterus, large body habitus, and bowel gas [46]. US Pelvis Transvaginal TVUS provides higher contrast and spatial resolution and should be combined with the TAUS whenever possible to evaluate suspected uterine fibroid [46,47]. TVUS has a reported sensitivity of 90% to 99% for detecting uterine fibroids and a sensitivity of 90% and specificity of 98% for the diagnosis of submucosal fibroids [43,48,49]. The limitations of TVUS are a limited depth of penetration and a shallow focal length that can limit the evaluation of large or subserosal/pedunculated fibroids. The presence of numerous fibroids may also pose challenge in clearly delineating and precisely measuring the fibroids because of too poor an acoustic window. US Duplex Doppler Pelvis Although Doppler imaging is labeled under separate imaging procedure per ACR methodology, this document considers it to be a standard component of pelvic US. Color and spectral Doppler are routinely used in pelvic US examinations to evaluate internal vascularity of pelvic/uterine findings and to differentiate between vascular and nonvascular tissue [47].
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3188532
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acrac_3188532_7
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Fibroids
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The growth of a uterine fibroid is proportional to its vascularity, and determining growth potential of the fibroid is helpful in clinical decision making [79,80]. Uterine artery Doppler flow measurements with peak systolic velocity >64 cm/s in uteri with fibroids have been shown as a predictor of UFE failure [81]. In a study by Nieuwenhuis et al [82], fibroid vascularization evaluated by 3-D TVUS with power Doppler correlated with fibroid volume and predicted fibroid growth rate per year. However, MRI pelvis has a higher sensitivity and accuracy than US in identifying number, location, size, volume, and vascularity of uterine fibroids for treatment planning [24,49,59]. Variant 3: Known fibroids. Surveillance or posttreatment imaging. CT Pelvis Although CT pelvis has no direct role in routine surveillance or posttreatment follow-up of uterine fibroids, CT, preferably with IV contrast, may be used following UFE in patients with pelvic pain, fever for acute postprocedural complications such as infection, hemorrhage, or pelvic venous thrombosis [83]. The overall serious post-UFE complication rate is 1.25%, with pulmonary embolism and infection (endometritis, pyometra, pyomyoma) occurring in up to 0.25% and 2% of patients, respectively [25,41,83]. MRI Pelvis When MRI is clinically indicated, the use of a gadolinium-based IV contrast agent is preferred [26]. Please see the ACR Manual on Contrast Media for additional information [27]. Routine posttreatment surveillance is controversial, and there is no consensus when to image asymptomatic women postintervention. Most studies evaluate patients immediately, 3 months, and/or 12 months after treatment and rely on T1-weighted, T2-weighted, and postcontrast sequences. Parameters commonly assessed include uterine volume, fibroid volume, percent infarcted/nonperfused volume, ovarian arterial collateral supply to the uterus, and fibroid location [25,41,67,70,83-87].
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Fibroids. The growth of a uterine fibroid is proportional to its vascularity, and determining growth potential of the fibroid is helpful in clinical decision making [79,80]. Uterine artery Doppler flow measurements with peak systolic velocity >64 cm/s in uteri with fibroids have been shown as a predictor of UFE failure [81]. In a study by Nieuwenhuis et al [82], fibroid vascularization evaluated by 3-D TVUS with power Doppler correlated with fibroid volume and predicted fibroid growth rate per year. However, MRI pelvis has a higher sensitivity and accuracy than US in identifying number, location, size, volume, and vascularity of uterine fibroids for treatment planning [24,49,59]. Variant 3: Known fibroids. Surveillance or posttreatment imaging. CT Pelvis Although CT pelvis has no direct role in routine surveillance or posttreatment follow-up of uterine fibroids, CT, preferably with IV contrast, may be used following UFE in patients with pelvic pain, fever for acute postprocedural complications such as infection, hemorrhage, or pelvic venous thrombosis [83]. The overall serious post-UFE complication rate is 1.25%, with pulmonary embolism and infection (endometritis, pyometra, pyomyoma) occurring in up to 0.25% and 2% of patients, respectively [25,41,83]. MRI Pelvis When MRI is clinically indicated, the use of a gadolinium-based IV contrast agent is preferred [26]. Please see the ACR Manual on Contrast Media for additional information [27]. Routine posttreatment surveillance is controversial, and there is no consensus when to image asymptomatic women postintervention. Most studies evaluate patients immediately, 3 months, and/or 12 months after treatment and rely on T1-weighted, T2-weighted, and postcontrast sequences. Parameters commonly assessed include uterine volume, fibroid volume, percent infarcted/nonperfused volume, ovarian arterial collateral supply to the uterus, and fibroid location [25,41,67,70,83-87].
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3188532
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acrac_3188532_8
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Fibroids
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Following technically successful UFE, >90% fibroid infarction on postcontrast imaging correlates with better symptom control and fewer reinterventions [88]. Fibroid location after treatment is also important, especially in cases of suspected fibroid expulsion, which occurs in 2.2% to 7.7% of cases [1,25,66]. Fibroids Specifically, intracavitary devascularized fibroid location predisposes to fibroid expulsion. Several studies show an association between diffusion-weighted imaging and ADC values and fibroid devascularization after UFE and MRgFUS [89-94]. Quantitative perfusion parameters have also been used to predict immediate MRgFUS ablation response [95]. US Pelvis Transabdominal A combination of TAUS and TVUS of the pelvis is a frequently used imaging modality in surveillance and posttreatment follow-up of known uterine fibroids [77,78]. TAUS is often useful in significantly enlarged fibroid uterus or large subserosal/pedunculated fibroids that can have poor visualization on TVUS because of limited field- of-view from poor acoustic penetration. Another potential limitation of TAUS is a poor acoustic window from decompressed urinary bladder, retroverted uterus, large body habitus, and bowel gas [46]. US Duplex Doppler Pelvis Although labeled under separate imaging procedure per ACR methodology, this document considers Doppler imaging to be a standard component of pelvic US. Color Doppler has been routinely used in pelvic US examinations to evaluate internal vascularity of pelvic/uterine findings and differentiate between vascular and nonvascular tissue [47]. UFE results in a marked reduction in fibroid size and disappearance of intrafibroid vascularity without a reduction in uterine vascularization that can be assessed with Doppler US [100].
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Fibroids. Following technically successful UFE, >90% fibroid infarction on postcontrast imaging correlates with better symptom control and fewer reinterventions [88]. Fibroid location after treatment is also important, especially in cases of suspected fibroid expulsion, which occurs in 2.2% to 7.7% of cases [1,25,66]. Fibroids Specifically, intracavitary devascularized fibroid location predisposes to fibroid expulsion. Several studies show an association between diffusion-weighted imaging and ADC values and fibroid devascularization after UFE and MRgFUS [89-94]. Quantitative perfusion parameters have also been used to predict immediate MRgFUS ablation response [95]. US Pelvis Transabdominal A combination of TAUS and TVUS of the pelvis is a frequently used imaging modality in surveillance and posttreatment follow-up of known uterine fibroids [77,78]. TAUS is often useful in significantly enlarged fibroid uterus or large subserosal/pedunculated fibroids that can have poor visualization on TVUS because of limited field- of-view from poor acoustic penetration. Another potential limitation of TAUS is a poor acoustic window from decompressed urinary bladder, retroverted uterus, large body habitus, and bowel gas [46]. US Duplex Doppler Pelvis Although labeled under separate imaging procedure per ACR methodology, this document considers Doppler imaging to be a standard component of pelvic US. Color Doppler has been routinely used in pelvic US examinations to evaluate internal vascularity of pelvic/uterine findings and differentiate between vascular and nonvascular tissue [47]. UFE results in a marked reduction in fibroid size and disappearance of intrafibroid vascularity without a reduction in uterine vascularization that can be assessed with Doppler US [100].
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3188532
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acrac_3098416_0
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Chronic Liver Disease
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Introduction/Background Chronic liver disease encompasses a variety of causes of chronic liver injury, including nonalcoholic fatty liver disease, hepatitis C, hepatitis B, alcohol-related liver disease, primary sclerosing cholangitis, autoimmune hepatitis, and others. These diseases can progress to hepatic fibrosis and cirrhosis, with associated complications of portal hypertension, gastrointestinal hemorrhage, refractory ascites, hepatic encephalopathy, and primary liver cancer [1- 3]. Liver disease accounts for approximately 2 million deaths per year worldwide, 1 million due to complications of cirrhosis and 1 million due to viral hepatitis and hepatocellular carcinoma. Cirrhosis and liver cancer account for 3.5% of all deaths worldwide [4]. In the United States, the leading cause of cirrhosis is hepatitis C, with approximately 1.3% of the population having chronic hepatitis C infection [1-3], and mortality related to cirrhosis and liver cancer is underestimated and may be increasing [5,6]. The progression of hepatic fibrosis to compensated cirrhosis to decompensated cirrhosis can be slow and clinically silent. Although the standard for diagnosis of hepatic fibrosis and cirrhosis is liver biopsy, this technique is costly, plagued by sampling errors, can be morbid, and is not well accepted for longitudinal disease monitoring [7,8]. Thus, accurate noninvasive methods are desperately needed for establishing and grading severity of liver fibrosis as well as monitoring disease progression or response to therapy. Although a variety of serum markers exist for this purpose, they are inaccurate for intermediate stages of fibrosis, and imaging by conventional ultrasound (US), CT, and MRI is frequently performed to assess for cirrhosis and its complications in this patient population [9]. More advanced techniques such as MR elastography and US have been shown to be more accurate than conventional morphological imaging methods and are gaining acceptance for these applications.
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Chronic Liver Disease. Introduction/Background Chronic liver disease encompasses a variety of causes of chronic liver injury, including nonalcoholic fatty liver disease, hepatitis C, hepatitis B, alcohol-related liver disease, primary sclerosing cholangitis, autoimmune hepatitis, and others. These diseases can progress to hepatic fibrosis and cirrhosis, with associated complications of portal hypertension, gastrointestinal hemorrhage, refractory ascites, hepatic encephalopathy, and primary liver cancer [1- 3]. Liver disease accounts for approximately 2 million deaths per year worldwide, 1 million due to complications of cirrhosis and 1 million due to viral hepatitis and hepatocellular carcinoma. Cirrhosis and liver cancer account for 3.5% of all deaths worldwide [4]. In the United States, the leading cause of cirrhosis is hepatitis C, with approximately 1.3% of the population having chronic hepatitis C infection [1-3], and mortality related to cirrhosis and liver cancer is underestimated and may be increasing [5,6]. The progression of hepatic fibrosis to compensated cirrhosis to decompensated cirrhosis can be slow and clinically silent. Although the standard for diagnosis of hepatic fibrosis and cirrhosis is liver biopsy, this technique is costly, plagued by sampling errors, can be morbid, and is not well accepted for longitudinal disease monitoring [7,8]. Thus, accurate noninvasive methods are desperately needed for establishing and grading severity of liver fibrosis as well as monitoring disease progression or response to therapy. Although a variety of serum markers exist for this purpose, they are inaccurate for intermediate stages of fibrosis, and imaging by conventional ultrasound (US), CT, and MRI is frequently performed to assess for cirrhosis and its complications in this patient population [9]. More advanced techniques such as MR elastography and US have been shown to be more accurate than conventional morphological imaging methods and are gaining acceptance for these applications.
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3098416
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acrac_3098416_1
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Chronic Liver Disease
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Hepatocellular carcinoma (HCC) is the most common primary liver cancer arising in patients with cirrhosis, and the American Association for the Study of Liver Disease (along with other major international guidelines) recommends surveillance for HCC in patients with cirrhosis who would benefit from early detection of HCC [10,11]. Imaging plays a central role in detection, staging, and treatment guidance for HCC. Surveillance has traditionally been performed with conventional US, followed by contrast-enhanced CT or MRI used for definitive diagnosis and staging of HCC [12,13]. However, there may be an emerging role for MRI-based surveillance in patients whose livers are poorly assessed by US. Contrast-enhanced US (CEUS) is becoming established as an accurate technique for assessment of liver masses, including HCC [14]. Discussion of Procedures by Variant Variant 1: Chronic liver disease. Diagnosis and staging of liver fibrosis. Initial imaging. Patients with chronic liver disease can present with findings of frank cirrhosis and portal hypertension, including jaundice and ascites. However, in many patients, the severity of liver disease is not apparent based on clinical or laboratory findings. In general, imaging can be helpful to confirm the presence of cirrhosis based on morphological aDuke University Medical Center, Durham, North Carolina. bPanel Vice Chair, Northwestern University, Chicago, Illinois. cPanel Chair, Johns Hopkins University School of Medicine, Baltimore, Maryland. dUniversity of Arizona, Banner University Medical Center, Tucson, Arizona. eBaylor University Medical Center, Dallas, Texas; American Association for the Study of Liver Diseases. fMontefiore Medical Center, Bronx, New York. gUMass Medical School, Worcester, Massachusetts. hUniversity of Florida College of Medicine, Gainesville, Florida. iNew York University Medical Center, New York, New York. jStanford University Medical Center, Stanford, California. kUniversity of Alabama Medical Center, Birmingham, Alabama.
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Chronic Liver Disease. Hepatocellular carcinoma (HCC) is the most common primary liver cancer arising in patients with cirrhosis, and the American Association for the Study of Liver Disease (along with other major international guidelines) recommends surveillance for HCC in patients with cirrhosis who would benefit from early detection of HCC [10,11]. Imaging plays a central role in detection, staging, and treatment guidance for HCC. Surveillance has traditionally been performed with conventional US, followed by contrast-enhanced CT or MRI used for definitive diagnosis and staging of HCC [12,13]. However, there may be an emerging role for MRI-based surveillance in patients whose livers are poorly assessed by US. Contrast-enhanced US (CEUS) is becoming established as an accurate technique for assessment of liver masses, including HCC [14]. Discussion of Procedures by Variant Variant 1: Chronic liver disease. Diagnosis and staging of liver fibrosis. Initial imaging. Patients with chronic liver disease can present with findings of frank cirrhosis and portal hypertension, including jaundice and ascites. However, in many patients, the severity of liver disease is not apparent based on clinical or laboratory findings. In general, imaging can be helpful to confirm the presence of cirrhosis based on morphological aDuke University Medical Center, Durham, North Carolina. bPanel Vice Chair, Northwestern University, Chicago, Illinois. cPanel Chair, Johns Hopkins University School of Medicine, Baltimore, Maryland. dUniversity of Arizona, Banner University Medical Center, Tucson, Arizona. eBaylor University Medical Center, Dallas, Texas; American Association for the Study of Liver Diseases. fMontefiore Medical Center, Bronx, New York. gUMass Medical School, Worcester, Massachusetts. hUniversity of Florida College of Medicine, Gainesville, Florida. iNew York University Medical Center, New York, New York. jStanford University Medical Center, Stanford, California. kUniversity of Alabama Medical Center, Birmingham, Alabama.
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3098416
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acrac_3098416_2
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Chronic Liver Disease
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lUniversity of Alabama Medical Center, Birmingham, Alabama. mJohns Hopkins Bayview Medical Center, Baltimore, Maryland. nUniversity of Illinois College of Medicine, Chicago, Illinois; American College of Physicians. oJohns Hopkins Hospital, Baltimore, Maryland. pSpecialty Chair, Virginia Commonwealth University Medical Center, Richmond, Virginia. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels. Participation by representatives from collaborating societies on the expert panel does not necessarily imply individual or society endorsement of the final document. Reprint requests to: [email protected] Chronic Liver Disease features. For patients without cirrhosis, determining the presence and severity of earlier stages of liver fibrosis may help guide management. CT Abdomen Noncontrast CT has limited utility in the assessment of hepatic fibrosis because it relies on the demonstration of gross structural changes, which are typically not present until very advanced stages of the disease. Contrast- enhanced CT can be more useful because it can demonstrate parenchymal heterogeneity and enhancement of lattice- like macroscopic bands of fibrosis throughout the hepatic parenchyma [21,22]. CT perfusion has been described for the assessment of hepatic fibrosis and cirrhosis, predominantly relying on increased proportion of arterial blood supply to the liver as fibrosis progresses [23]. However, this methodology is highly technique dependent and requires substantial postprocessing and therefore is not considered a clinical standard method for establishing the diagnosis of cirrhosis. There is no relevant literature that demonstrates incremental value of combining noncontrast with contrast-enhanced CT for this application. FDG-PET/CT Skull Base to Mid-Thigh Fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG)-PET is not a useful test for detecting liver fibrosis.
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Chronic Liver Disease. lUniversity of Alabama Medical Center, Birmingham, Alabama. mJohns Hopkins Bayview Medical Center, Baltimore, Maryland. nUniversity of Illinois College of Medicine, Chicago, Illinois; American College of Physicians. oJohns Hopkins Hospital, Baltimore, Maryland. pSpecialty Chair, Virginia Commonwealth University Medical Center, Richmond, Virginia. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels. Participation by representatives from collaborating societies on the expert panel does not necessarily imply individual or society endorsement of the final document. Reprint requests to: [email protected] Chronic Liver Disease features. For patients without cirrhosis, determining the presence and severity of earlier stages of liver fibrosis may help guide management. CT Abdomen Noncontrast CT has limited utility in the assessment of hepatic fibrosis because it relies on the demonstration of gross structural changes, which are typically not present until very advanced stages of the disease. Contrast- enhanced CT can be more useful because it can demonstrate parenchymal heterogeneity and enhancement of lattice- like macroscopic bands of fibrosis throughout the hepatic parenchyma [21,22]. CT perfusion has been described for the assessment of hepatic fibrosis and cirrhosis, predominantly relying on increased proportion of arterial blood supply to the liver as fibrosis progresses [23]. However, this methodology is highly technique dependent and requires substantial postprocessing and therefore is not considered a clinical standard method for establishing the diagnosis of cirrhosis. There is no relevant literature that demonstrates incremental value of combining noncontrast with contrast-enhanced CT for this application. FDG-PET/CT Skull Base to Mid-Thigh Fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG)-PET is not a useful test for detecting liver fibrosis.
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3098416
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acrac_3098416_3
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Chronic Liver Disease
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Data are limited regarding its utility, and no advantage over alternative imaging or serum tests has been demonstrated. MR Elastography Abdomen MR elastography is currently the most accurate imaging modality for the diagnosis and staging of hepatic fibrosis [24,25]. MR elastography compares favorably with US shear wave elastography (SWE), in part, because of improved performance in patients with obesity [26]. MR elastography does have limitations in patients with hepatic iron deposition and patients imaged at 3T due to susceptibility artifacts, which can result in undersampling of the liver or nondiagnostic evaluations. Stiffness measurement may also be confounded by parenchymal edema, inflammation, cholestasis, cardiogenic hepatic congestion, recent meal, and other factors [27]. MRI Abdomen Conventional MRI can be used to assess the same structural changes as those visualized on CT, with the added advantage of greater visibility of bands of fibrosis on both noncontrast and contrast-enhanced sequences [28]. However, its utility for detecting early liver fibrosis remains limited because these changes do not occur until fibrosis has progressed to a very advanced stage. A number of advanced MRI techniques have been assessed for detecting liver fibrosis. Diffusion-weighted imaging has been used to assess the restriction of free water proton movement in the hepatic parenchyma as a marker of collagen deposition, the microscopic manifestation of liver fibrosis. A meta-analysis of studies on diffusion- weighted imaging for this application showed that diffusion-weighted imaging was most useful for detecting advanced fibrosis but had lower performance for detecting early fibrosis (sensitivity 77%, specificity 78%) [29]. Additionally, questions about the optimal acquisition technique and image processing methodologies (apparent diffusion coefficient, intravoxel incoherent motion, etc) remain unresolved.
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Chronic Liver Disease. Data are limited regarding its utility, and no advantage over alternative imaging or serum tests has been demonstrated. MR Elastography Abdomen MR elastography is currently the most accurate imaging modality for the diagnosis and staging of hepatic fibrosis [24,25]. MR elastography compares favorably with US shear wave elastography (SWE), in part, because of improved performance in patients with obesity [26]. MR elastography does have limitations in patients with hepatic iron deposition and patients imaged at 3T due to susceptibility artifacts, which can result in undersampling of the liver or nondiagnostic evaluations. Stiffness measurement may also be confounded by parenchymal edema, inflammation, cholestasis, cardiogenic hepatic congestion, recent meal, and other factors [27]. MRI Abdomen Conventional MRI can be used to assess the same structural changes as those visualized on CT, with the added advantage of greater visibility of bands of fibrosis on both noncontrast and contrast-enhanced sequences [28]. However, its utility for detecting early liver fibrosis remains limited because these changes do not occur until fibrosis has progressed to a very advanced stage. A number of advanced MRI techniques have been assessed for detecting liver fibrosis. Diffusion-weighted imaging has been used to assess the restriction of free water proton movement in the hepatic parenchyma as a marker of collagen deposition, the microscopic manifestation of liver fibrosis. A meta-analysis of studies on diffusion- weighted imaging for this application showed that diffusion-weighted imaging was most useful for detecting advanced fibrosis but had lower performance for detecting early fibrosis (sensitivity 77%, specificity 78%) [29]. Additionally, questions about the optimal acquisition technique and image processing methodologies (apparent diffusion coefficient, intravoxel incoherent motion, etc) remain unresolved.
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3098416
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acrac_3098416_4
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Chronic Liver Disease
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MR perfusion techniques have been described and found to be relatively accurate for the diagnosis and staging of liver fibrosis [30]. However, like CT perfusion, these are dependent on details of the acquisition and processing techniques and can be quite laborious, so they are not broadly used in clinical practice. US Abdomen Conventional US can be used in the assessment of liver fibrosis for detecting ultrastructural changes such as surface nodularity, coarsened echotexture, and lobar atrophy/hypertrophy, similar to conventional CT and MRI [24,33,34]. Chronic Liver Disease US has an advantage in that high spatial resolution imaging of the liver surface can be performed with high frequency transducers, which can demonstrate subtle surface nodularity. US Abdomen with IV Contrast US abdomen with IV contrast or CEUS has been assessed for evaluation of liver fibrosis. Similar to CT and MRI perfusion techniques, CEUS uses contrast media transit characteristics to make deductions about liver hemodynamics that relate to the presence and severity of liver fibrosis [35,36]. Although early data on the utility of CEUS for assessing liver fibrosis and portal hypertension are promising, this is an area of ongoing research at this time. US Duplex Doppler Abdomen Doppler US can demonstrate hemodynamic alterations indicative of portal hypertension, though these are typically only seen in the setting of long-standing fibrosis or cirrhosis [40,41]. Though only moderately sensitive for advanced fibrosis/cirrhosis, it can be used for initial assessment of patients with suspected long-standing chronic liver disease in combination with conventional grayscale US. Cirrhosis due to vascular conditions is a special case in which surveillance for HCC is more complex. Underlying vascular conditions include Budd-Chiari syndrome, hepatic congestion particularly in the setting of congenital heart disease, hereditary hemorrhagic telangiectasia, and others.
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Chronic Liver Disease. MR perfusion techniques have been described and found to be relatively accurate for the diagnosis and staging of liver fibrosis [30]. However, like CT perfusion, these are dependent on details of the acquisition and processing techniques and can be quite laborious, so they are not broadly used in clinical practice. US Abdomen Conventional US can be used in the assessment of liver fibrosis for detecting ultrastructural changes such as surface nodularity, coarsened echotexture, and lobar atrophy/hypertrophy, similar to conventional CT and MRI [24,33,34]. Chronic Liver Disease US has an advantage in that high spatial resolution imaging of the liver surface can be performed with high frequency transducers, which can demonstrate subtle surface nodularity. US Abdomen with IV Contrast US abdomen with IV contrast or CEUS has been assessed for evaluation of liver fibrosis. Similar to CT and MRI perfusion techniques, CEUS uses contrast media transit characteristics to make deductions about liver hemodynamics that relate to the presence and severity of liver fibrosis [35,36]. Although early data on the utility of CEUS for assessing liver fibrosis and portal hypertension are promising, this is an area of ongoing research at this time. US Duplex Doppler Abdomen Doppler US can demonstrate hemodynamic alterations indicative of portal hypertension, though these are typically only seen in the setting of long-standing fibrosis or cirrhosis [40,41]. Though only moderately sensitive for advanced fibrosis/cirrhosis, it can be used for initial assessment of patients with suspected long-standing chronic liver disease in combination with conventional grayscale US. Cirrhosis due to vascular conditions is a special case in which surveillance for HCC is more complex. Underlying vascular conditions include Budd-Chiari syndrome, hepatic congestion particularly in the setting of congenital heart disease, hereditary hemorrhagic telangiectasia, and others.
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3098416
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acrac_3098416_5
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Chronic Liver Disease
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The utility of imaging for diagnosis of cirrhosis and accuracy for characterizing HCC is less well established, particularly because these patients often develop benign regenerative liver nodules. Optimal utilization of imaging in these patients must be established for each condition based on available data and is not addressed in this document. Chronic Liver Disease in whom the utility of US may be limited. Little value has been demonstrated for the addition of noncontrast to contrast-enhanced CT in this setting. FDG-PET/CT Skull Base to Mid-Thigh FDG-PET/CT is not a useful test for screening or surveillance for HCC. FDG uptake by HCC is highly variable, and combined with high background liver FDG uptake, the PET portion of these examinations adds little to multiphase contrast-enhanced CT [49]. MR Elastography Abdomen MR elastography has been investigated for the assessment of focal liver lesions with modest success [50]. However, limited spatial resolution and coverage of MR elastography renders it of limited utility for screening and surveillance. MRI Abdomen Dynamic contrast-enhanced MRI has been shown to be the most accurate modality in detecting and characterizing HCC, with sensitivity reported between 47% to 95% even for lesions <2 cm [46-48,51-54]. MRI most commonly serves as a second-line confirmatory diagnostic test for assessing nodules detected with US, though it may have a role for screening and surveillance of patients in whom US is expected to be of lower utility [55]. Because the detection and characterization of HCC relies mainly on the perfusion features of liver lesions, MRI without IV contrast is not typically performed for this purpose. MRI with hepatobiliary contrast agents has been shown to be similarly sensitive for detection of HCC compared with extracellular agents, and potentially more sensitive (up to 96% in a recent meta-analysis but only 88% in a more recent study) for detection of small lesions [56].
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Chronic Liver Disease. The utility of imaging for diagnosis of cirrhosis and accuracy for characterizing HCC is less well established, particularly because these patients often develop benign regenerative liver nodules. Optimal utilization of imaging in these patients must be established for each condition based on available data and is not addressed in this document. Chronic Liver Disease in whom the utility of US may be limited. Little value has been demonstrated for the addition of noncontrast to contrast-enhanced CT in this setting. FDG-PET/CT Skull Base to Mid-Thigh FDG-PET/CT is not a useful test for screening or surveillance for HCC. FDG uptake by HCC is highly variable, and combined with high background liver FDG uptake, the PET portion of these examinations adds little to multiphase contrast-enhanced CT [49]. MR Elastography Abdomen MR elastography has been investigated for the assessment of focal liver lesions with modest success [50]. However, limited spatial resolution and coverage of MR elastography renders it of limited utility for screening and surveillance. MRI Abdomen Dynamic contrast-enhanced MRI has been shown to be the most accurate modality in detecting and characterizing HCC, with sensitivity reported between 47% to 95% even for lesions <2 cm [46-48,51-54]. MRI most commonly serves as a second-line confirmatory diagnostic test for assessing nodules detected with US, though it may have a role for screening and surveillance of patients in whom US is expected to be of lower utility [55]. Because the detection and characterization of HCC relies mainly on the perfusion features of liver lesions, MRI without IV contrast is not typically performed for this purpose. MRI with hepatobiliary contrast agents has been shown to be similarly sensitive for detection of HCC compared with extracellular agents, and potentially more sensitive (up to 96% in a recent meta-analysis but only 88% in a more recent study) for detection of small lesions [56].
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3098416
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acrac_3098416_6
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Chronic Liver Disease
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However, challenges with transient respiratory motion artifacts, judging washout, and other technical limitations must be considered [57,58]. US Abdomen with IV Contrast CEUS has been shown to be highly sensitive for the diagnosis of HCC at centers of excellence [14,67,68]. However, CEUS requires focused observation of a single region of interest, and although the ability to reinject after a period of washout allows for more than one region to be evaluated during a single examination, this may not be well-suited for whole-liver assessment as is needed for screening and surveillance [69]. Chronic Liver Disease US Shear Wave Elastography Abdomen The use of SWE has been described for assessment of focal liver lesions in a limited number of small studies [70,71]. However, SWE assessments are typically performed slice by slice; thus, the technique is poorly suited to whole- liver surveillance. To date, most reported investigations on the application of SWE in the liver have focused on liver fibrosis assessment and, to a lesser extent, on differentiating benign from malignant focal lesions. US Duplex Doppler Abdomen Doppler US is typically performed in conjunction with conventional grayscale US assessment. The duplex Doppler component may add value to the grayscale examination, allowing tumor in vein to be more readily identified. Variant 3: Chronic liver disease. Previous diagnosis of HCC. Post-treatment monitoring for HCC. Treatment options for patients with HCC may include liver transplantation, surgical resection, external beam radiation therapy, chemotherapy, and locoregional treatments, including percutaneous ablative and embolic modalities. After liver transplantation and surgical resection with negative margins, the goal of post-treatment monitoring is surveillance for new foci of HCC. After treatments in which the HCC is not actually removed, both monitoring of the treatment site as well as surveillance for distant foci of HCC must be accomplished.
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Chronic Liver Disease. However, challenges with transient respiratory motion artifacts, judging washout, and other technical limitations must be considered [57,58]. US Abdomen with IV Contrast CEUS has been shown to be highly sensitive for the diagnosis of HCC at centers of excellence [14,67,68]. However, CEUS requires focused observation of a single region of interest, and although the ability to reinject after a period of washout allows for more than one region to be evaluated during a single examination, this may not be well-suited for whole-liver assessment as is needed for screening and surveillance [69]. Chronic Liver Disease US Shear Wave Elastography Abdomen The use of SWE has been described for assessment of focal liver lesions in a limited number of small studies [70,71]. However, SWE assessments are typically performed slice by slice; thus, the technique is poorly suited to whole- liver surveillance. To date, most reported investigations on the application of SWE in the liver have focused on liver fibrosis assessment and, to a lesser extent, on differentiating benign from malignant focal lesions. US Duplex Doppler Abdomen Doppler US is typically performed in conjunction with conventional grayscale US assessment. The duplex Doppler component may add value to the grayscale examination, allowing tumor in vein to be more readily identified. Variant 3: Chronic liver disease. Previous diagnosis of HCC. Post-treatment monitoring for HCC. Treatment options for patients with HCC may include liver transplantation, surgical resection, external beam radiation therapy, chemotherapy, and locoregional treatments, including percutaneous ablative and embolic modalities. After liver transplantation and surgical resection with negative margins, the goal of post-treatment monitoring is surveillance for new foci of HCC. After treatments in which the HCC is not actually removed, both monitoring of the treatment site as well as surveillance for distant foci of HCC must be accomplished.
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3098416
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acrac_3098416_7
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Chronic Liver Disease
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Thus, whole- liver surveillance remains an important goal after treatment. CT Abdomen CT of the abdomen without and with IV contrast is an accurate method for detecting recurrence of HCC following locoregional therapy, resection, or transplantation. After locoregional therapy, including a precontrast phase, CT is strongly recommended because treatment can render a lesion or perilesional treatment zone high in attenuation (particularly when ethiodized oil is used in embolization), which can confound the interpretation of the hepatic arterial phase [72,73]. Noncontrast CT has a limited role because the detection of recurrent HCC relies primarily on detecting abnormal tumor perfusion. Dual-energy CT can be utilized to derive virtual unenhanced images and/or iodine maps for the same purpose as a dedicated precontrast acquisition. [74]. The National Comprehensive Cancer Network guidelines recommend CT or MRI every 3 to 6 months for 2 years and then every 6 to 12 months after HCC resection, whereas the European Association for the Study of the Liver recommends multiphase CT or MRI to assess response 1 month after resection or locoregional or systemic therapies, followed by one imaging technique every 3 months to complete at least 2 years, and then regular US every 6 months thereafter [75]. FDG-PET/CT Skull Base to Mid-Thigh The utility of FDG-PET/CT in HCC patients has primarily been investigated in the pretreatment setting; little data are available regarding post-treatment monitoring [76]. Because of the need for multiple repeated examinations and efficacy of multiphase contrast-enhanced CT and MRI, FDG-PET/CT is infrequently used for monitoring for HCC recurrence. MR Elastography Abdomen MR elastography has been investigated for the assessment of focal liver lesions with modest success [50]. However, limited spatial resolution and coverage of MR elastography renders it of limited utility for screening and surveillance.
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Chronic Liver Disease. Thus, whole- liver surveillance remains an important goal after treatment. CT Abdomen CT of the abdomen without and with IV contrast is an accurate method for detecting recurrence of HCC following locoregional therapy, resection, or transplantation. After locoregional therapy, including a precontrast phase, CT is strongly recommended because treatment can render a lesion or perilesional treatment zone high in attenuation (particularly when ethiodized oil is used in embolization), which can confound the interpretation of the hepatic arterial phase [72,73]. Noncontrast CT has a limited role because the detection of recurrent HCC relies primarily on detecting abnormal tumor perfusion. Dual-energy CT can be utilized to derive virtual unenhanced images and/or iodine maps for the same purpose as a dedicated precontrast acquisition. [74]. The National Comprehensive Cancer Network guidelines recommend CT or MRI every 3 to 6 months for 2 years and then every 6 to 12 months after HCC resection, whereas the European Association for the Study of the Liver recommends multiphase CT or MRI to assess response 1 month after resection or locoregional or systemic therapies, followed by one imaging technique every 3 months to complete at least 2 years, and then regular US every 6 months thereafter [75]. FDG-PET/CT Skull Base to Mid-Thigh The utility of FDG-PET/CT in HCC patients has primarily been investigated in the pretreatment setting; little data are available regarding post-treatment monitoring [76]. Because of the need for multiple repeated examinations and efficacy of multiphase contrast-enhanced CT and MRI, FDG-PET/CT is infrequently used for monitoring for HCC recurrence. MR Elastography Abdomen MR elastography has been investigated for the assessment of focal liver lesions with modest success [50]. However, limited spatial resolution and coverage of MR elastography renders it of limited utility for screening and surveillance.
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3098416
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acrac_3098416_8
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Chronic Liver Disease
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MRI Abdomen MRI of the abdomen without and with IV contrast is highly sensitive for detecting HCC recurrence. Multiple contrast mechanisms (perfusion, diffusion, hepatobiliary agent uptake, intrinsic T1- and T2-weighted signal intensity) can be used for assessment; however, arterial phase hyperperfusion remains the mainstay for detection of HCC recurrence. Both the National Comprehensive Cancer Network and the European Association for the Study of the Liver recommend CT or MRI at regular intervals for at least 2 years for follow-up of patients with treated HCC [77]. The role of hepatobiliary MRI in this setting remains controversial. It has been shown to increase sensitivity for detection of small lesions, but may overdiagnose premalignant lesions [78]. In addition, imaging artifacts are more common with gadoxetate disodium, the primary agent used for hepatobiliary imaging, and use of hepatobiliary agents may reduce the yield of the early perfusion assessment of lesions [57]. Because the detection and characterization of HCC relies mainly on the perfusional features of liver lesions, MRI without IV contrast is not typically performed for this purpose. However, noncontrast MRI may be a reasonable modality for surveillance, because it offers the best differentiation between types of soft tissues of the available noncontrast modalities. Chronic Liver Disease US Abdomen Because of the importance of vascular perfusion and the absence of morphological changes in early HCC recurrence, US is not typically utilized as the only surveillance modality for assessing for recurrent HCC following treatment. The European Association for the Study of the Liver recommends multiphase CT or MRI to assess response 1 month after resection or locoregional or systemic therapies, followed by one imaging technique every 3 months to complete at least 2 years, and then regular US every 6 months thereafter [77].
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Chronic Liver Disease. MRI Abdomen MRI of the abdomen without and with IV contrast is highly sensitive for detecting HCC recurrence. Multiple contrast mechanisms (perfusion, diffusion, hepatobiliary agent uptake, intrinsic T1- and T2-weighted signal intensity) can be used for assessment; however, arterial phase hyperperfusion remains the mainstay for detection of HCC recurrence. Both the National Comprehensive Cancer Network and the European Association for the Study of the Liver recommend CT or MRI at regular intervals for at least 2 years for follow-up of patients with treated HCC [77]. The role of hepatobiliary MRI in this setting remains controversial. It has been shown to increase sensitivity for detection of small lesions, but may overdiagnose premalignant lesions [78]. In addition, imaging artifacts are more common with gadoxetate disodium, the primary agent used for hepatobiliary imaging, and use of hepatobiliary agents may reduce the yield of the early perfusion assessment of lesions [57]. Because the detection and characterization of HCC relies mainly on the perfusional features of liver lesions, MRI without IV contrast is not typically performed for this purpose. However, noncontrast MRI may be a reasonable modality for surveillance, because it offers the best differentiation between types of soft tissues of the available noncontrast modalities. Chronic Liver Disease US Abdomen Because of the importance of vascular perfusion and the absence of morphological changes in early HCC recurrence, US is not typically utilized as the only surveillance modality for assessing for recurrent HCC following treatment. The European Association for the Study of the Liver recommends multiphase CT or MRI to assess response 1 month after resection or locoregional or systemic therapies, followed by one imaging technique every 3 months to complete at least 2 years, and then regular US every 6 months thereafter [77].
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3098416
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acrac_69460_0
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First Trimester Vaginal Bleeding
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Introduction/Background Ultrasound (US) is the primary imaging modality in the evaluation of patients presenting with vaginal bleeding in the first trimester of pregnancy. Magnetic resonance imaging (MRI) and computed tomography (CT) play a minor role in problem-solving the causes of bleeding but may be useful when US is severely limited, for an unusual ectopic pregnancy, or when uncommon diagnoses are suspected. US correlated with serum human chorionic gonadotrophin (hCG) levels and clinical presentation can usually differentiate causes of first-trimester bleeding. These include normal intrauterine pregnancy (IUP) with or without a subchorionic hematoma, nonviable IUP, gestational trophoblastic disease (GTD), and ectopic pregnancy, which can all present with vaginal bleeding. Bleeding in the first trimester occurs in 7% to 27% of pregnancies, with an overall risk of miscarriage of approximately 12% [1]. US can usually differentiate an intrauterine from an ectopic pregnancy and a viable from a nonviable IUP. An overview of relevant US findings follows. Although it is important to diagnose ectopic pregnancies and nonviable IUPs, one should also guard against injury to normal pregnancies. Potential harm to a normal pregnancy can occur because of overinterpretation of a single US, misunderstanding the usefulness of the discriminatory level or serial values of hCG, and inappropriate treatment with methotrexate or dilation and curettage [2]. Variant 1: First trimester vaginal bleeding. Positive urine or serum pregnancy test. US Transvaginal Intrauterine fluid collection The first visible US evidence of an IUP is a small spherical fluid collection with a hyperechoic rim, representing the gestational sac, located within the endometrium. Using high-frequency transvaginal transducers (generally about 7 MHz or higher), gestational sacs as small as 2 to 3 mm in mean sac diameter (MSD) may be visualized, corresponding to 4.5 to 5 weeks of gestation [3].
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First Trimester Vaginal Bleeding. Introduction/Background Ultrasound (US) is the primary imaging modality in the evaluation of patients presenting with vaginal bleeding in the first trimester of pregnancy. Magnetic resonance imaging (MRI) and computed tomography (CT) play a minor role in problem-solving the causes of bleeding but may be useful when US is severely limited, for an unusual ectopic pregnancy, or when uncommon diagnoses are suspected. US correlated with serum human chorionic gonadotrophin (hCG) levels and clinical presentation can usually differentiate causes of first-trimester bleeding. These include normal intrauterine pregnancy (IUP) with or without a subchorionic hematoma, nonviable IUP, gestational trophoblastic disease (GTD), and ectopic pregnancy, which can all present with vaginal bleeding. Bleeding in the first trimester occurs in 7% to 27% of pregnancies, with an overall risk of miscarriage of approximately 12% [1]. US can usually differentiate an intrauterine from an ectopic pregnancy and a viable from a nonviable IUP. An overview of relevant US findings follows. Although it is important to diagnose ectopic pregnancies and nonviable IUPs, one should also guard against injury to normal pregnancies. Potential harm to a normal pregnancy can occur because of overinterpretation of a single US, misunderstanding the usefulness of the discriminatory level or serial values of hCG, and inappropriate treatment with methotrexate or dilation and curettage [2]. Variant 1: First trimester vaginal bleeding. Positive urine or serum pregnancy test. US Transvaginal Intrauterine fluid collection The first visible US evidence of an IUP is a small spherical fluid collection with a hyperechoic rim, representing the gestational sac, located within the endometrium. Using high-frequency transvaginal transducers (generally about 7 MHz or higher), gestational sacs as small as 2 to 3 mm in mean sac diameter (MSD) may be visualized, corresponding to 4.5 to 5 weeks of gestation [3].
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First Trimester Vaginal Bleeding
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Prior to the identification of a yolk sac or embryo in the gestational sac, the intradecidual sign may be helpful to confirm an IUP. The intradecidual sign consists of an intrauterine fluid collection with a hyperechoic rim located in the endometrium separate from the central echogenic line that represents the collapsed endometrial cavity [4,5]. This sign, which can be visualized as early as 4.5 weeks, increases the probability of an IUP but is not reliable for diagnosing an IUP [6,7]. It can be difficult to apply the intradecidual sign in some patients, as the central echogenic line is not always evident. The double decidual sac sign, typically defined as two echogenic rings around the intrauterine fluid collection, is another finding that seems to increase the likelihood of an IUP but is not a reliable sign and is of limited usefulness for confirming an IUP [7-9]. The intradecidual sign and the double decidual sac sign both have poor interobserver agreement and neither is required for the diagnosis of an IUP [7]. Before a yolk sac or embryo is seen, there has been concern that fluid in the endometrial cavity, sometimes termed a pseudogestational sac, might be confused for a gestational sac. However, pseudogestational sacs can usually be recognized based on their shape (acute angle at the edge), contents (internal echoes), or location (in the endometrial cavity) [10]. If a nonspecific fluid collection in the uterus does not have the features of a pseudogestational sac, it should be interpreted as likely representing a gestational sac, and one should generally Reprint requests to: [email protected] First Trimester Vaginal Bleeding not undertake a treatment that could cause unintended harm to an IUP [7,10]. Rarely, a decidual cyst [11] could be mistaken for a gestational sac but usually does not have an echogenic rim and is usually not adjacent to the central echogenic line of the collapsed endometrial cavity.
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First Trimester Vaginal Bleeding. Prior to the identification of a yolk sac or embryo in the gestational sac, the intradecidual sign may be helpful to confirm an IUP. The intradecidual sign consists of an intrauterine fluid collection with a hyperechoic rim located in the endometrium separate from the central echogenic line that represents the collapsed endometrial cavity [4,5]. This sign, which can be visualized as early as 4.5 weeks, increases the probability of an IUP but is not reliable for diagnosing an IUP [6,7]. It can be difficult to apply the intradecidual sign in some patients, as the central echogenic line is not always evident. The double decidual sac sign, typically defined as two echogenic rings around the intrauterine fluid collection, is another finding that seems to increase the likelihood of an IUP but is not a reliable sign and is of limited usefulness for confirming an IUP [7-9]. The intradecidual sign and the double decidual sac sign both have poor interobserver agreement and neither is required for the diagnosis of an IUP [7]. Before a yolk sac or embryo is seen, there has been concern that fluid in the endometrial cavity, sometimes termed a pseudogestational sac, might be confused for a gestational sac. However, pseudogestational sacs can usually be recognized based on their shape (acute angle at the edge), contents (internal echoes), or location (in the endometrial cavity) [10]. If a nonspecific fluid collection in the uterus does not have the features of a pseudogestational sac, it should be interpreted as likely representing a gestational sac, and one should generally Reprint requests to: [email protected] First Trimester Vaginal Bleeding not undertake a treatment that could cause unintended harm to an IUP [7,10]. Rarely, a decidual cyst [11] could be mistaken for a gestational sac but usually does not have an echogenic rim and is usually not adjacent to the central echogenic line of the collapsed endometrial cavity.
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acrac_69460_2
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First Trimester Vaginal Bleeding
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The discriminatory level of hCG refers to the level at which a gestational sac should always be seen on transvaginal US in a normal singleton IUP and has historically been suggested as 1,000 to 2,000 mIU/mL [12,13]. However, even a level of 2,000 mIU/mL has been found to be too low to exclude a normal IUP [14-16]. If there is no transvaginal US evidence of a gestational sac when a single serum hCG is 3,000 mIU/mL or higher, it is unlikely there will be a viable IUP [17]. For a hemodynamically stable patient with no sonographic evidence of an IUP or ectopic pregnancy, management decisions should generally not be made based on a single hCG level [16,17] . Follow-up hCG assay and US are usually appropriate in such a scenario. Definite intrauterine gestation The yolk sac, a thin-walled, spherical structure with an anechoic center, is the first sonographic feature that confirms an IUP [8]. It is usually visualized by transvaginal US in a gestational sac >8 mm in MSD [18]; however, in some normal pregnancies the gestational sac will be larger before a yolk sac is seen [19]. The embryo will initially appear as a thickened, linear echogenic structure at the edge of the yolk sac. With transvaginal US, the embryo is usually seen by about 6 weeks gestational age and by the time the gestational sac grows to a MSD of 16 mm; however, in some normal pregnancies the gestational sac will be larger before an embryo is seen [20]. Once an IUP is definitely established by US, various US findings may be seen that are associated with a nonviable IUP. These include bradycardia [23,24], small gestational sac compared to embryo [25], enlarged amniotic cavity [26], empty amniotic cavity [27], absence of cardiac activity with visualization of the amnion [28], and abnormal size or shape of the yolk sac [29]. However, these findings are not definitive for a nonviable IUP, and in these situations, follow-up US in correlation with serial quantitative serum beta hCG measurements is often useful.
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First Trimester Vaginal Bleeding. The discriminatory level of hCG refers to the level at which a gestational sac should always be seen on transvaginal US in a normal singleton IUP and has historically been suggested as 1,000 to 2,000 mIU/mL [12,13]. However, even a level of 2,000 mIU/mL has been found to be too low to exclude a normal IUP [14-16]. If there is no transvaginal US evidence of a gestational sac when a single serum hCG is 3,000 mIU/mL or higher, it is unlikely there will be a viable IUP [17]. For a hemodynamically stable patient with no sonographic evidence of an IUP or ectopic pregnancy, management decisions should generally not be made based on a single hCG level [16,17] . Follow-up hCG assay and US are usually appropriate in such a scenario. Definite intrauterine gestation The yolk sac, a thin-walled, spherical structure with an anechoic center, is the first sonographic feature that confirms an IUP [8]. It is usually visualized by transvaginal US in a gestational sac >8 mm in MSD [18]; however, in some normal pregnancies the gestational sac will be larger before a yolk sac is seen [19]. The embryo will initially appear as a thickened, linear echogenic structure at the edge of the yolk sac. With transvaginal US, the embryo is usually seen by about 6 weeks gestational age and by the time the gestational sac grows to a MSD of 16 mm; however, in some normal pregnancies the gestational sac will be larger before an embryo is seen [20]. Once an IUP is definitely established by US, various US findings may be seen that are associated with a nonviable IUP. These include bradycardia [23,24], small gestational sac compared to embryo [25], enlarged amniotic cavity [26], empty amniotic cavity [27], absence of cardiac activity with visualization of the amnion [28], and abnormal size or shape of the yolk sac [29]. However, these findings are not definitive for a nonviable IUP, and in these situations, follow-up US in correlation with serial quantitative serum beta hCG measurements is often useful.
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First Trimester Vaginal Bleeding
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Subchorionic hematomas are not an infrequent finding during the first trimester. They are usually small and not thought to substantially increase the risk of a nonviable pregnancy. Large (two-thirds or more of the gestational sac circumference) subchorionic hematomas may be associated with an increased risk of nonviable pregnancy [30]. Ectopic pregnancy Whenever an IUP is not identified in a patient with a positive pregnancy test, extrauterine locations for the pregnancy should be carefully evaluated [31,32]. This involves identification of the ovaries and corpus luteum along with a careful search for any extraovarian mass that is not a paraovarian cyst or pedunculated fibroid because the vast majority of ectopic pregnancies are in the fallopian tube. Ectopic pregnancies are located ipsilateral to the corpus luteum in 70% to 80% of cases [33,34] and it is important to distinguish between the First Trimester Vaginal Bleeding Although visualization of an extrauterine gestational sac with a live embryo is 100% specific for an ectopic pregnancy, this situation is uncommon [39]. More common, though slightly less specific, is an extrauterine mass with a fluid center and hyperechoic periphery, which has been termed a tubal ring [40,41]. Additionally, the ectopic pregnancy may appear as a nonspecific heterogeneous mass with no identifiable gestational sac within it. This latter appearance has been reported as the most common sonographic finding of a tubal pregnancy [39]. Even with such a nonspecific-appearing mass, tubal pregnancy is likely when the mass is outside the ovary (with no other obvious cause, such as a pedunculated fibroid or paraovarian cyst) in a patient with a positive serum hCG and no sonographic evidence of an IUP [41]. Given the potential for inappropriate management with methotrexate or surgical intervention, the diagnosis of ectopic pregnancy should generally be based on positive findings and not solely on the absence of an IUP.
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First Trimester Vaginal Bleeding. Subchorionic hematomas are not an infrequent finding during the first trimester. They are usually small and not thought to substantially increase the risk of a nonviable pregnancy. Large (two-thirds or more of the gestational sac circumference) subchorionic hematomas may be associated with an increased risk of nonviable pregnancy [30]. Ectopic pregnancy Whenever an IUP is not identified in a patient with a positive pregnancy test, extrauterine locations for the pregnancy should be carefully evaluated [31,32]. This involves identification of the ovaries and corpus luteum along with a careful search for any extraovarian mass that is not a paraovarian cyst or pedunculated fibroid because the vast majority of ectopic pregnancies are in the fallopian tube. Ectopic pregnancies are located ipsilateral to the corpus luteum in 70% to 80% of cases [33,34] and it is important to distinguish between the First Trimester Vaginal Bleeding Although visualization of an extrauterine gestational sac with a live embryo is 100% specific for an ectopic pregnancy, this situation is uncommon [39]. More common, though slightly less specific, is an extrauterine mass with a fluid center and hyperechoic periphery, which has been termed a tubal ring [40,41]. Additionally, the ectopic pregnancy may appear as a nonspecific heterogeneous mass with no identifiable gestational sac within it. This latter appearance has been reported as the most common sonographic finding of a tubal pregnancy [39]. Even with such a nonspecific-appearing mass, tubal pregnancy is likely when the mass is outside the ovary (with no other obvious cause, such as a pedunculated fibroid or paraovarian cyst) in a patient with a positive serum hCG and no sonographic evidence of an IUP [41]. Given the potential for inappropriate management with methotrexate or surgical intervention, the diagnosis of ectopic pregnancy should generally be based on positive findings and not solely on the absence of an IUP.
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First Trimester Vaginal Bleeding
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Assessment of any free intraperitoneal fluid is important in the evaluation for an ectopic pregnancy. In this setting, echoes within the free fluid are often due to blood. Trace anechoic free fluid in the pelvis is generally normal. The presence of more than a normal small amount of free fluid or echoes within the fluid, even without identification of an extraovarian mass, is concerning for an ectopic pregnancy [42-44]. However, this finding is not specific and can also occur for other reasons, such as rupture of a hemorrhagic ovarian cyst with an early, nonvisualized IUP. A minority of ectopic pregnancies occur in locations other than the fallopian tube. The most common nontubal locations are interstitial, cervical, and within a Cesarean section scar. Three-dimensional US may be useful if an interstitial pregnancy is suspected but the diagnosis is uncertain based on 2-D US [45]. Rudimentary horn and abdominal pregnancies are less common, and ovarian ectopic pregnancy is rare. Coexisting intrauterine and extrauterine pregnancy (sometimes referred to as a heterotopic pregnancy) is rare, though is more likely to occur in women undergoing assisted reproduction techniques [46]. In general, for a woman with a spontaneously occurring pregnancy, identification of an IUP excludes a coexisting ectopic pregnancy with near complete certainty. However, the adnexa should still be routinely evaluated. Other causes of PUL include an early IUP (<4.5-5 weeks) or a nonvisualized ectopic pregnancy. A small minority of patients with PUL (probably about 7%-20% but likely more toward the lower end of that range), will later be diagnosed with an ectopic pregnancy [48]. Patients with a PUL can pose a diagnostic challenge. If the patient is hemodynamically stable, follow-up hCG and/or US should generally be performed before surgical or medical therapy is undertaken, regardless of the initial hCG level [15,16].
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First Trimester Vaginal Bleeding. Assessment of any free intraperitoneal fluid is important in the evaluation for an ectopic pregnancy. In this setting, echoes within the free fluid are often due to blood. Trace anechoic free fluid in the pelvis is generally normal. The presence of more than a normal small amount of free fluid or echoes within the fluid, even without identification of an extraovarian mass, is concerning for an ectopic pregnancy [42-44]. However, this finding is not specific and can also occur for other reasons, such as rupture of a hemorrhagic ovarian cyst with an early, nonvisualized IUP. A minority of ectopic pregnancies occur in locations other than the fallopian tube. The most common nontubal locations are interstitial, cervical, and within a Cesarean section scar. Three-dimensional US may be useful if an interstitial pregnancy is suspected but the diagnosis is uncertain based on 2-D US [45]. Rudimentary horn and abdominal pregnancies are less common, and ovarian ectopic pregnancy is rare. Coexisting intrauterine and extrauterine pregnancy (sometimes referred to as a heterotopic pregnancy) is rare, though is more likely to occur in women undergoing assisted reproduction techniques [46]. In general, for a woman with a spontaneously occurring pregnancy, identification of an IUP excludes a coexisting ectopic pregnancy with near complete certainty. However, the adnexa should still be routinely evaluated. Other causes of PUL include an early IUP (<4.5-5 weeks) or a nonvisualized ectopic pregnancy. A small minority of patients with PUL (probably about 7%-20% but likely more toward the lower end of that range), will later be diagnosed with an ectopic pregnancy [48]. Patients with a PUL can pose a diagnostic challenge. If the patient is hemodynamically stable, follow-up hCG and/or US should generally be performed before surgical or medical therapy is undertaken, regardless of the initial hCG level [15,16].
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First Trimester Vaginal Bleeding
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Gestational trophoblastic disease When US does not show an intrauterine gestational sac, but rather a hyperechoic area in the endometrium with multiple cystic spaces [51], one should consider a complete molar pregnancy, the most common form of GTD. In the earlier part of the first trimester, this classic appearance may be absent and the sonographic findings more variable [52,53]. Complete molar pregnancy can sometimes appear similar to RPOC. Partial molar pregnancy can First Trimester Vaginal Bleeding be more difficult to diagnose sonographically than complete molar pregnancy [54,55] but should be considered if an embryo is present with cystic change in the early placenta. The US findings of partial molar pregnancy overlap those of a nonviable IUP with hydropic degeneration of the early placenta. The hCG is often, but not always, inappropriately elevated with GTD. Definitive diagnosis is based on histopathological evaluation of uterine contents. US Transabdominal Most research studies have used transvaginal US, and there is little evidence in regards to diagnosis of nonviable IUP with transabdominal US alone. Transabdominal US may be adequate in some patients if the diagnosis is clear, such as when a viable IUP and normal adnexa are demonstrated in a patient with no risk factors for heterotopic pregnancy. Transabdominal US is more likely to be adequate later in the first trimester as opposed to the early first trimester. Ectopic pregnancy If an abnormal amount of free intraperitoneal fluid is identified in the pelvis, transabdominal US should be used to evaluate the flanks and dependent locations in the right upper (Morison pouch) and left upper quadrants. It is difficult to reliably predict tubal rupture by US [39]. Larger amounts of free intraperitoneal fluid correlate with ruptured ectopic pregnancy, but in about one-third of cases with a large amount of free intraperitoneal fluid, the fallopian tubes are intact [56].
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First Trimester Vaginal Bleeding. Gestational trophoblastic disease When US does not show an intrauterine gestational sac, but rather a hyperechoic area in the endometrium with multiple cystic spaces [51], one should consider a complete molar pregnancy, the most common form of GTD. In the earlier part of the first trimester, this classic appearance may be absent and the sonographic findings more variable [52,53]. Complete molar pregnancy can sometimes appear similar to RPOC. Partial molar pregnancy can First Trimester Vaginal Bleeding be more difficult to diagnose sonographically than complete molar pregnancy [54,55] but should be considered if an embryo is present with cystic change in the early placenta. The US findings of partial molar pregnancy overlap those of a nonviable IUP with hydropic degeneration of the early placenta. The hCG is often, but not always, inappropriately elevated with GTD. Definitive diagnosis is based on histopathological evaluation of uterine contents. US Transabdominal Most research studies have used transvaginal US, and there is little evidence in regards to diagnosis of nonviable IUP with transabdominal US alone. Transabdominal US may be adequate in some patients if the diagnosis is clear, such as when a viable IUP and normal adnexa are demonstrated in a patient with no risk factors for heterotopic pregnancy. Transabdominal US is more likely to be adequate later in the first trimester as opposed to the early first trimester. Ectopic pregnancy If an abnormal amount of free intraperitoneal fluid is identified in the pelvis, transabdominal US should be used to evaluate the flanks and dependent locations in the right upper (Morison pouch) and left upper quadrants. It is difficult to reliably predict tubal rupture by US [39]. Larger amounts of free intraperitoneal fluid correlate with ruptured ectopic pregnancy, but in about one-third of cases with a large amount of free intraperitoneal fluid, the fallopian tubes are intact [56].
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First Trimester Vaginal Bleeding
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Clotted blood in the pelvis can sometimes be mistaken for mesentery or blend in with adjacent organs such as the uterus and be difficult to recognize. US Duplex Doppler When a normal or potentially normal IUP is present, pulsed Doppler US (whether spectral, color, or power Doppler) of the pregnancy should generally be avoided in the first trimester due to concerns about potential bioeffects in the developing embryo [57-59]. Documentation of embryonic cardiac activity is best done with M- mode US as the heart rate can be measured. Video clips can also be used to document embryonic cardiac activity. Once a normal IUP has been excluded, Doppler US may be useful when other diagnoses such as RPOC are suspected. Doppler US is not generally needed to make a diagnosis of GTD, but may be helpful as an ancillary tool in the management of some patients with GTD [60,61]. Doppler US is rarely useful for diagnosing tubal pregnancies as both the corpus luteum and a tubal pregnancy often have flow detected peripherally. Although Doppler US could conceivably be useful in some nontubal ectopic pregnancies such as cervical, interstitial, or Cesarean section scar pregnancies, its diagnostic utility for these diagnoses has not been well established in the literature. MRI While an early pregnancy may be recognized on MRI, it generally is due to unintentional imaging of the pregnancy [67]. MRI is rarely needed for evaluating an IUP or tubal pregnancy. However, one may occasionally recognize tubal pregnancies on MRI [68], and MRI may be helpful as a problem-solving tool for nontubal ectopic pregnancies or GTD [69-71]. MRI may also help in cases of unusual implantation sites or in women with uterine anomalies. In pregnancy, gadolinium should be used with caution and only when critical and the potential benefits are felt to be justified [72]. Gadolinium is not generally recommended in a normal first-trimester pregnancy. MRI without gadolinium is thought to be safe in the first trimester of pregnancy [73].
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First Trimester Vaginal Bleeding. Clotted blood in the pelvis can sometimes be mistaken for mesentery or blend in with adjacent organs such as the uterus and be difficult to recognize. US Duplex Doppler When a normal or potentially normal IUP is present, pulsed Doppler US (whether spectral, color, or power Doppler) of the pregnancy should generally be avoided in the first trimester due to concerns about potential bioeffects in the developing embryo [57-59]. Documentation of embryonic cardiac activity is best done with M- mode US as the heart rate can be measured. Video clips can also be used to document embryonic cardiac activity. Once a normal IUP has been excluded, Doppler US may be useful when other diagnoses such as RPOC are suspected. Doppler US is not generally needed to make a diagnosis of GTD, but may be helpful as an ancillary tool in the management of some patients with GTD [60,61]. Doppler US is rarely useful for diagnosing tubal pregnancies as both the corpus luteum and a tubal pregnancy often have flow detected peripherally. Although Doppler US could conceivably be useful in some nontubal ectopic pregnancies such as cervical, interstitial, or Cesarean section scar pregnancies, its diagnostic utility for these diagnoses has not been well established in the literature. MRI While an early pregnancy may be recognized on MRI, it generally is due to unintentional imaging of the pregnancy [67]. MRI is rarely needed for evaluating an IUP or tubal pregnancy. However, one may occasionally recognize tubal pregnancies on MRI [68], and MRI may be helpful as a problem-solving tool for nontubal ectopic pregnancies or GTD [69-71]. MRI may also help in cases of unusual implantation sites or in women with uterine anomalies. In pregnancy, gadolinium should be used with caution and only when critical and the potential benefits are felt to be justified [72]. Gadolinium is not generally recommended in a normal first-trimester pregnancy. MRI without gadolinium is thought to be safe in the first trimester of pregnancy [73].
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acrac_69460_7
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First Trimester Vaginal Bleeding
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First Trimester Vaginal Bleeding RPOC may be identified by MRI, but MRI has little role in making the diagnosis of RPOC. RPOC and GTD may both manifest as an enhancing endometrial mass but are usually distinguishable on clinical grounds [74]. Contrast-enhanced pelvic MRI may be helpful to evaluate the extent of myometrial invasion and local extrauterine spread of GTD [75]. Uterine AVM can also be diagnosed with MRI [76]. CT An early IUP may be recognized on CT, but it is usually due to unintentional imaging of the pregnancy [67]. Because of its ionizing radiation, CT is generally not performed to evaluate vaginal bleeding in the first trimester of pregnancy. CT may identify an ectopic pregnancy [68], but reported cases of ectopic pregnancy diagnosed on CT were often performed for other reasons or in patients not known to be pregnant [77,78]. When a patient is clinically unstable, emergent care should generally not be delayed by additional imaging with CT or MRI. RPOC may be identified by CT, particularly when an enhancing mass is seen, but CT has little role in making the diagnosis of RPOC and the findings overlap those of GTD [74]. In patients with GTD, CT may be helpful in evaluating the extent of extrauterine spread [75]. Summary of Recommendations Transvaginal and transabdominal US are the most appropriate imaging modalities in patients with abnormal vaginal bleeding in the first trimester of pregnancy. Transvaginal US is generally the preferred modality. Transabdominal US is often complementary to transvaginal US and may sometimes be adequate alone. Although there are references that report on studies with design limitations, 6 good-quality studies provide good evidence. Safety Considerations in Pregnant Patients Imaging of the pregnant patient can be challenging, particularly with respect to minimizing radiation exposure and risk.
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First Trimester Vaginal Bleeding. First Trimester Vaginal Bleeding RPOC may be identified by MRI, but MRI has little role in making the diagnosis of RPOC. RPOC and GTD may both manifest as an enhancing endometrial mass but are usually distinguishable on clinical grounds [74]. Contrast-enhanced pelvic MRI may be helpful to evaluate the extent of myometrial invasion and local extrauterine spread of GTD [75]. Uterine AVM can also be diagnosed with MRI [76]. CT An early IUP may be recognized on CT, but it is usually due to unintentional imaging of the pregnancy [67]. Because of its ionizing radiation, CT is generally not performed to evaluate vaginal bleeding in the first trimester of pregnancy. CT may identify an ectopic pregnancy [68], but reported cases of ectopic pregnancy diagnosed on CT were often performed for other reasons or in patients not known to be pregnant [77,78]. When a patient is clinically unstable, emergent care should generally not be delayed by additional imaging with CT or MRI. RPOC may be identified by CT, particularly when an enhancing mass is seen, but CT has little role in making the diagnosis of RPOC and the findings overlap those of GTD [74]. In patients with GTD, CT may be helpful in evaluating the extent of extrauterine spread [75]. Summary of Recommendations Transvaginal and transabdominal US are the most appropriate imaging modalities in patients with abnormal vaginal bleeding in the first trimester of pregnancy. Transvaginal US is generally the preferred modality. Transabdominal US is often complementary to transvaginal US and may sometimes be adequate alone. Although there are references that report on studies with design limitations, 6 good-quality studies provide good evidence. Safety Considerations in Pregnant Patients Imaging of the pregnant patient can be challenging, particularly with respect to minimizing radiation exposure and risk.
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acrac_3099659_0
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Thoracic Aortic Aneurysm or Dissection Treatment Planning and Follow Up
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Introduction/Background Since the first thoracic aorta endograft device was approved by the FDA in 2005, thoracic endovascular aortic repair (TEVAR) has undergone rapid evolution and is now applied to a range of aortic pathologies, including trauma, aneurysm, dissections, intramural hematoma (IMH), penetrating atherosclerotic ulcer (PAU), and even persistent congenital malformations such as aortic co-arctation [1,2]. TEVAR has also been used as a bridge treatment before open repair in patients with aortic infections who develop circulatory collapse or fistulization to adjacent structures [3,4]. Compared with open surgical repair, TEVAR has demonstrated favorable perioperative morbidity and mortality data for many forms of thoracic aorta pathology [5]. TEVAR also allows for intervention in patients with more extensive comorbidities that would otherwise preclude open surgical repair [6]. In certain patient groups, including variant anatomy such as aberrant right subclavian artery with aneurysmal degeneration of the vessel origin, hybrid open and endovascular procedures are performed wherein affected visceral branch vessels are surgically revascularized with concomitant or staged endovascular exclusion of the primary aortic pathology [7-9]. Thoracic aortic aneurysms are defined as permanent dilation of the thoracic aorta by more than 2 SDs over the mean. Based on population studies, the thoracic aorta is generally considered aneurysmal at 4 cm. Up to one-third of thoracic aortic aneurysms extend into the abdominal aorta, increasing complexity of endovascular or surgical repair [10]. Intervention is indicated when aneurysm diameter exceeds 5.5 cm or demonstrates rapid growth [10]. More conservative thresholds are implemented in patients with underlying connective tissue disorders or a bicuspid aortic valve.
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Thoracic Aortic Aneurysm or Dissection Treatment Planning and Follow Up. Introduction/Background Since the first thoracic aorta endograft device was approved by the FDA in 2005, thoracic endovascular aortic repair (TEVAR) has undergone rapid evolution and is now applied to a range of aortic pathologies, including trauma, aneurysm, dissections, intramural hematoma (IMH), penetrating atherosclerotic ulcer (PAU), and even persistent congenital malformations such as aortic co-arctation [1,2]. TEVAR has also been used as a bridge treatment before open repair in patients with aortic infections who develop circulatory collapse or fistulization to adjacent structures [3,4]. Compared with open surgical repair, TEVAR has demonstrated favorable perioperative morbidity and mortality data for many forms of thoracic aorta pathology [5]. TEVAR also allows for intervention in patients with more extensive comorbidities that would otherwise preclude open surgical repair [6]. In certain patient groups, including variant anatomy such as aberrant right subclavian artery with aneurysmal degeneration of the vessel origin, hybrid open and endovascular procedures are performed wherein affected visceral branch vessels are surgically revascularized with concomitant or staged endovascular exclusion of the primary aortic pathology [7-9]. Thoracic aortic aneurysms are defined as permanent dilation of the thoracic aorta by more than 2 SDs over the mean. Based on population studies, the thoracic aorta is generally considered aneurysmal at 4 cm. Up to one-third of thoracic aortic aneurysms extend into the abdominal aorta, increasing complexity of endovascular or surgical repair [10]. Intervention is indicated when aneurysm diameter exceeds 5.5 cm or demonstrates rapid growth [10]. More conservative thresholds are implemented in patients with underlying connective tissue disorders or a bicuspid aortic valve.
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3099659
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acrac_3099659_1
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Thoracic Aortic Aneurysm or Dissection Treatment Planning and Follow Up
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Acute aortic syndromes, broadly defined as a disease spectrum encompassing PAU, IMH, and aortic dissection, may be treated with conservative medical therapy or surgical or endovascular intervention, depending on the presentation. The goal of endovascular stent grafting in these conditions is to maintain true lumen patency, prevent aneurysmal degeneration, and, in the case of dissection, seal intimal tears and induce thrombosis in the false lumen [11]. When clinically suspected, acute aortic syndrome requires immediate diagnostic evaluation to exclude an impending vascular catastrophe. Indications for surgical intervention in these conditions include lack of symptomatic improvement with medical therapy, resistant hypertension, rapid expansion of IMH or false lumen, and concern for impending rupture [5,12-15]. It has been shown that nearly 50% of acute aortic syndrome patients will develop a recurrent acute aortic event within 1 to 2 years of initial presentation, underscoring the need for close follow-up in this population [16]. With the exception of trauma, the vast majority of aortic pathologies arise in patients aged 60 to 80 years. Risk factors include male gender, long-standing hypertension, hyperlipidemia, arteriosclerosis, and smoking [17]. However, there are a variety of genetic syndromes and single-gene mutation conditions that confer a higher risk of thoracic aortic aneurysm and dissection in younger patients, including Marfan syndrome (associated with FBN1 mutations), Loeys-Dietz syndrome (associated with TGFB and SMAD mutations), and familial thoracic aorta aneurysm leading to aortic dissections (associated with ACTA2 mutations) [18]. Even when syndromes are not suspected, patients with a bicuspid aortic valve or a strong family history of aortic disease have higher risk of
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Thoracic Aortic Aneurysm or Dissection Treatment Planning and Follow Up. Acute aortic syndromes, broadly defined as a disease spectrum encompassing PAU, IMH, and aortic dissection, may be treated with conservative medical therapy or surgical or endovascular intervention, depending on the presentation. The goal of endovascular stent grafting in these conditions is to maintain true lumen patency, prevent aneurysmal degeneration, and, in the case of dissection, seal intimal tears and induce thrombosis in the false lumen [11]. When clinically suspected, acute aortic syndrome requires immediate diagnostic evaluation to exclude an impending vascular catastrophe. Indications for surgical intervention in these conditions include lack of symptomatic improvement with medical therapy, resistant hypertension, rapid expansion of IMH or false lumen, and concern for impending rupture [5,12-15]. It has been shown that nearly 50% of acute aortic syndrome patients will develop a recurrent acute aortic event within 1 to 2 years of initial presentation, underscoring the need for close follow-up in this population [16]. With the exception of trauma, the vast majority of aortic pathologies arise in patients aged 60 to 80 years. Risk factors include male gender, long-standing hypertension, hyperlipidemia, arteriosclerosis, and smoking [17]. However, there are a variety of genetic syndromes and single-gene mutation conditions that confer a higher risk of thoracic aortic aneurysm and dissection in younger patients, including Marfan syndrome (associated with FBN1 mutations), Loeys-Dietz syndrome (associated with TGFB and SMAD mutations), and familial thoracic aorta aneurysm leading to aortic dissections (associated with ACTA2 mutations) [18]. Even when syndromes are not suspected, patients with a bicuspid aortic valve or a strong family history of aortic disease have higher risk of
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The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels. Participation by representatives from collaborating societies on the expert panel does not necessarily imply individual or society endorsement of the final document. Reprint requests to: [email protected] Regardless of the pathology at play, the TEVAR procedure is similar. Access in TEVAR procedures is increasingly obtained percutaneously via the common femoral artery, although femoral artery cutdowns are still performed in up to 20% of cases. Although obesity was once considered a relative contraindication to percutaneous access, recent literature has demonstrated that it does not affect procedural success rates in the hands of an experienced surgeon or interventionalist [24]. The most important factor in percutaneous vessel selection appears to be vessel diameter, with common femoral artery diameters >8 to 9 mm exhibiting lower rates of complication [25,26]. Careful attention to preoperative imaging is then paid to the involved landing zones of the thoracic aorta. Proximal and distal landing zones should ideally be 2 to 3 cm in length to ensure an adequate seal and decreased rates of endoleaks, aneurysmal degeneration, and device migration [27]. When the proximal landing zone approaches the aortic arch vessels, the possibility of the stent graft occluding a vessel ostium arises. In such cases, vascular bypass or a staged or hybrid approach may be necessary to ensure patency. If aortic pathology extends into the abdominal aorta, care must be taken to assess for possible stent coverage of major branch vessels; when this situation arises, more involved repairs are necessary.
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Thoracic Aortic Aneurysm or Dissection Treatment Planning and Follow Up. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels. Participation by representatives from collaborating societies on the expert panel does not necessarily imply individual or society endorsement of the final document. Reprint requests to: [email protected] Regardless of the pathology at play, the TEVAR procedure is similar. Access in TEVAR procedures is increasingly obtained percutaneously via the common femoral artery, although femoral artery cutdowns are still performed in up to 20% of cases. Although obesity was once considered a relative contraindication to percutaneous access, recent literature has demonstrated that it does not affect procedural success rates in the hands of an experienced surgeon or interventionalist [24]. The most important factor in percutaneous vessel selection appears to be vessel diameter, with common femoral artery diameters >8 to 9 mm exhibiting lower rates of complication [25,26]. Careful attention to preoperative imaging is then paid to the involved landing zones of the thoracic aorta. Proximal and distal landing zones should ideally be 2 to 3 cm in length to ensure an adequate seal and decreased rates of endoleaks, aneurysmal degeneration, and device migration [27]. When the proximal landing zone approaches the aortic arch vessels, the possibility of the stent graft occluding a vessel ostium arises. In such cases, vascular bypass or a staged or hybrid approach may be necessary to ensure patency. If aortic pathology extends into the abdominal aorta, care must be taken to assess for possible stent coverage of major branch vessels; when this situation arises, more involved repairs are necessary.
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Despite the promise of TEVAR, it must be emphasized that the procedure is technically complex and has significant perioperative mortality of up to 12.5%, as reported in one series examining thoracoabdominal aneurysm endograft repair [28]. Frequent intraoperative complications include damage of the target vessel and its branches, device malposition, and access problems. Significant perioperative complications abound, including stroke, persistent renal dysfunction, and paraplegia or paraparesis secondary to spinal cord ischemia. [7,29]. Because late endoleaks have been reported in 10% to 41% of cases, continuous surveillance imaging is necessary to gauge the need for reintervention [30]. Additional postoperative complications include progressive aneurysmal degeneration of the aorta as well as potentially life-threatening complications such as retrograde dissection [31]. A commonly cited disadvantage of TEVAR with respect to open repair is the high rate of reintervention. For example, a recent study demonstrated a 32% reintervention rate at 4.7 years after aortic dissection repair [32]. A caveat is that the presence of an existing endograft can reduce operative risk in subsequent procedures. In cases of distal aneurysmal degeneration in the setting of prior TEVAR for chronic type B dissection, the indwelling endograft can serve as the attachment point for a new aortic graft, thereby reducing the extent and risk associated with reintervention [33]. Open surgical repair remains the treatment of choice in cases of acute Stanford type A dissection. This is because of the myriad anatomic constraints imposed by the proximity to the coronary ostia, aortic root or valve, and brachiocephalic trunk [11]. Use of TEVAR in asymptomatic, uncomplicated, chronic Stanford type B dissection is also controversial, with mixed survival benefit results when comparing TEVAR with optimized medical therapy [34,35].
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Thoracic Aortic Aneurysm or Dissection Treatment Planning and Follow Up. Despite the promise of TEVAR, it must be emphasized that the procedure is technically complex and has significant perioperative mortality of up to 12.5%, as reported in one series examining thoracoabdominal aneurysm endograft repair [28]. Frequent intraoperative complications include damage of the target vessel and its branches, device malposition, and access problems. Significant perioperative complications abound, including stroke, persistent renal dysfunction, and paraplegia or paraparesis secondary to spinal cord ischemia. [7,29]. Because late endoleaks have been reported in 10% to 41% of cases, continuous surveillance imaging is necessary to gauge the need for reintervention [30]. Additional postoperative complications include progressive aneurysmal degeneration of the aorta as well as potentially life-threatening complications such as retrograde dissection [31]. A commonly cited disadvantage of TEVAR with respect to open repair is the high rate of reintervention. For example, a recent study demonstrated a 32% reintervention rate at 4.7 years after aortic dissection repair [32]. A caveat is that the presence of an existing endograft can reduce operative risk in subsequent procedures. In cases of distal aneurysmal degeneration in the setting of prior TEVAR for chronic type B dissection, the indwelling endograft can serve as the attachment point for a new aortic graft, thereby reducing the extent and risk associated with reintervention [33]. Open surgical repair remains the treatment of choice in cases of acute Stanford type A dissection. This is because of the myriad anatomic constraints imposed by the proximity to the coronary ostia, aortic root or valve, and brachiocephalic trunk [11]. Use of TEVAR in asymptomatic, uncomplicated, chronic Stanford type B dissection is also controversial, with mixed survival benefit results when comparing TEVAR with optimized medical therapy [34,35].
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Relative contraindications to TEVAR include inadequate proximal or distal seal zones, aortic size discrepancies with respect to manufacturer guidelines, inadequate access, and extensive circumferential thrombus or atheroma at the desired landing zones [27]. Imaging plays a vital role in the pre- and postintervention assessment of TEVAR patients. Accurate characterization of pathology and evaluation for high-risk anatomic features are necessary in the planning phase, whereas careful assessment for graft stability, aortic lumen diameter, and presence of endoleak are paramount in the follow-up period. Because imaging studies carry inherent risk, careful attention must be paid to utilize the most efficacious study that will limit morbidity to the patient while identifying important complications before they become problematic. One finding that has become increasingly clear is that the thoracic aorta demonstrates dynamic changes after TEVAR. As the natural history of post-TEVAR patients evolves, the importance of these gradual changes will become clearer. For example, up to 73% of patients undergoing repair of acute type B aortic dissection will show aortic growth or new aneurysm at 5 years after TEVAR [14]. Although reintervention is not necessary in all cases, close follow-up is mandatory given the propensity for dynamic vascular changes over time. Therefore, TEVAR should be thought of more as a chronic management tool than as definitive intervention. Thoracic Aorta Interventional Planning and Follow-Up Overview of Imaging Modalities A variety of imaging modalities are available for the evaluation and follow-up of thoracic aortic pathology. Advances in imaging technology over the past 2 decades have greatly expanded the role of noninvasive cross- sectional imaging in the pre- and postintervention periods.
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Thoracic Aortic Aneurysm or Dissection Treatment Planning and Follow Up. Relative contraindications to TEVAR include inadequate proximal or distal seal zones, aortic size discrepancies with respect to manufacturer guidelines, inadequate access, and extensive circumferential thrombus or atheroma at the desired landing zones [27]. Imaging plays a vital role in the pre- and postintervention assessment of TEVAR patients. Accurate characterization of pathology and evaluation for high-risk anatomic features are necessary in the planning phase, whereas careful assessment for graft stability, aortic lumen diameter, and presence of endoleak are paramount in the follow-up period. Because imaging studies carry inherent risk, careful attention must be paid to utilize the most efficacious study that will limit morbidity to the patient while identifying important complications before they become problematic. One finding that has become increasingly clear is that the thoracic aorta demonstrates dynamic changes after TEVAR. As the natural history of post-TEVAR patients evolves, the importance of these gradual changes will become clearer. For example, up to 73% of patients undergoing repair of acute type B aortic dissection will show aortic growth or new aneurysm at 5 years after TEVAR [14]. Although reintervention is not necessary in all cases, close follow-up is mandatory given the propensity for dynamic vascular changes over time. Therefore, TEVAR should be thought of more as a chronic management tool than as definitive intervention. Thoracic Aorta Interventional Planning and Follow-Up Overview of Imaging Modalities A variety of imaging modalities are available for the evaluation and follow-up of thoracic aortic pathology. Advances in imaging technology over the past 2 decades have greatly expanded the role of noninvasive cross- sectional imaging in the pre- and postintervention periods.
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Computed tomography angiography (CTA) and, to a slightly lesser extent, magnetic resonance angiography (MRA) are now the preferred modalities in the assessment of the thoracic aorta given superior anatomic accuracy, capacity to discern relevant complications, and ability to infer dynamic vascular information [36]. Catheter angiography has largely been replaced by CTA and MRA for diagnostic evaluation but remains a useful tool in cases where acute intervention is required. Ultrasound (US), echocardiography, radiography, and select nuclear medicine studies currently play an adjunctive role in the evaluation and follow-up of thoracic aortic disease and are principally utilized to answer specific anatomic and prognostic questions. A variety of factors contributes to the appropriateness of each imaging study, including acuity of the pathologic process, planned intervention, patient age, medical comorbidities, and endograft composition. For the purposes of distinguishing between CT and CTA, ACR AC topics use the definition in the Practice Parameter for the Performance and Interpretation of Body Computed Tomography Angiography (CTA) [37]: All elements are essential: 1) timing, 2) reconstructions/reformats, and 3) 3-D renderings. Standard CTs with contrast also include timing issues and reconstructions/reformats. Only in CTA, however, is 3-D rendering a required element. This corresponds to the definitions that the Centers for Medicare & Medicaid Services has applied to the Current Procedural Terminology codes. Discussion of Procedures by Variant Variant 1: Planning for pre-thoracic endovascular repair (TEVAR) of thoracic aorta disease. CTA Multidetector CT is the imaging modality of choice for preoperative assessment before TEVAR because of short scan times and superior spatial and temporal resolution [38,39]. CTA is unmatched in its ability to provide isotropic data as well as robust and homogeneous intraluminal contrast enhancement [36].
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Thoracic Aortic Aneurysm or Dissection Treatment Planning and Follow Up. Computed tomography angiography (CTA) and, to a slightly lesser extent, magnetic resonance angiography (MRA) are now the preferred modalities in the assessment of the thoracic aorta given superior anatomic accuracy, capacity to discern relevant complications, and ability to infer dynamic vascular information [36]. Catheter angiography has largely been replaced by CTA and MRA for diagnostic evaluation but remains a useful tool in cases where acute intervention is required. Ultrasound (US), echocardiography, radiography, and select nuclear medicine studies currently play an adjunctive role in the evaluation and follow-up of thoracic aortic disease and are principally utilized to answer specific anatomic and prognostic questions. A variety of factors contributes to the appropriateness of each imaging study, including acuity of the pathologic process, planned intervention, patient age, medical comorbidities, and endograft composition. For the purposes of distinguishing between CT and CTA, ACR AC topics use the definition in the Practice Parameter for the Performance and Interpretation of Body Computed Tomography Angiography (CTA) [37]: All elements are essential: 1) timing, 2) reconstructions/reformats, and 3) 3-D renderings. Standard CTs with contrast also include timing issues and reconstructions/reformats. Only in CTA, however, is 3-D rendering a required element. This corresponds to the definitions that the Centers for Medicare & Medicaid Services has applied to the Current Procedural Terminology codes. Discussion of Procedures by Variant Variant 1: Planning for pre-thoracic endovascular repair (TEVAR) of thoracic aorta disease. CTA Multidetector CT is the imaging modality of choice for preoperative assessment before TEVAR because of short scan times and superior spatial and temporal resolution [38,39]. CTA is unmatched in its ability to provide isotropic data as well as robust and homogeneous intraluminal contrast enhancement [36].
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In cases of proximal thoracic aorta pathology, electrocardiography (ECG) gating can help achieve motion-free images along with ideal contrast enhancement. Acquisition of thin-section (0.5 to 2.0 mm) axial images with subsequent reconstruction of multiplanar reformats, maximum-intensity projections, curved planar reformats, and volume-rendered images allows for precise assessment of aortic anatomy [10,26]. Centerline or double oblique measurements are critical to avoid errors based on aortic obliquity; such measurements are easily obtained with modern postprocessing software [40]. More advanced postprocessing techniques such as 3-D virtual angioscopy, which affords a virtual endoluminal view, have shown utility in the surgical planning period [41]. Because thoracic aorta pathology often extends to involve the abdominal aorta, imaging of the chest, abdomen, and pelvis is standard in evaluation of vascular pathology. CTA can also identify higher-risk features and findings that may predict higher rates of postintervention complications. For example, it has been shown that increasing aortic tortuosity, which can be expressed as index values based on CTA measurements, is associated with increased risk of endoleak, stroke, and reduced survival after TEVAR for thoracic aortic aneurysm [42,43]. In patients with acute aortic dissection, the presence of a single entry, as opposed to multiple sites, is associated with higher aortic growth rates, possibly because of deranged inflow and outflow dynamics; CTA has been shown to reliably detect entry tears with 82% sensitivity and 100% specificity [44]. When abdominal visceral branches are involved and there is potential for celiac trunk or superior mesenteric artery coverage by the stent graft, CTA can help determine the presence of collateral vessels [45]. In the absence of collaterals, an open surgical or hybrid approach may be necessary to avoid visceral ischemia.
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Thoracic Aortic Aneurysm or Dissection Treatment Planning and Follow Up. In cases of proximal thoracic aorta pathology, electrocardiography (ECG) gating can help achieve motion-free images along with ideal contrast enhancement. Acquisition of thin-section (0.5 to 2.0 mm) axial images with subsequent reconstruction of multiplanar reformats, maximum-intensity projections, curved planar reformats, and volume-rendered images allows for precise assessment of aortic anatomy [10,26]. Centerline or double oblique measurements are critical to avoid errors based on aortic obliquity; such measurements are easily obtained with modern postprocessing software [40]. More advanced postprocessing techniques such as 3-D virtual angioscopy, which affords a virtual endoluminal view, have shown utility in the surgical planning period [41]. Because thoracic aorta pathology often extends to involve the abdominal aorta, imaging of the chest, abdomen, and pelvis is standard in evaluation of vascular pathology. CTA can also identify higher-risk features and findings that may predict higher rates of postintervention complications. For example, it has been shown that increasing aortic tortuosity, which can be expressed as index values based on CTA measurements, is associated with increased risk of endoleak, stroke, and reduced survival after TEVAR for thoracic aortic aneurysm [42,43]. In patients with acute aortic dissection, the presence of a single entry, as opposed to multiple sites, is associated with higher aortic growth rates, possibly because of deranged inflow and outflow dynamics; CTA has been shown to reliably detect entry tears with 82% sensitivity and 100% specificity [44]. When abdominal visceral branches are involved and there is potential for celiac trunk or superior mesenteric artery coverage by the stent graft, CTA can help determine the presence of collateral vessels [45]. In the absence of collaterals, an open surgical or hybrid approach may be necessary to avoid visceral ischemia.
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CTA may also be able to guide device selection. One complication after TEVAR is the development of a bird- beak endograft configuration in the proximal landing zone, which portends a higher risk of endoleak. This configuration results most commonly when the proximal landing zone sits within a highly curved or angulated Thoracic Aorta Interventional Planning and Follow-Up aortic arch [46]. Specially designed endografts that are less susceptible to these morphologic changes can therefore be selected when preoperative imaging identifies problematic anatomy. An important subset of TEVAR is its use in repair of pathologies involving the aortic arch. A detailed understanding of the spatial relationship of the arch vessels and the luminal changes throughout the diseased arch is required for proper patient and device selection [47]. Minimum proximal and distal landing-zone intervals are necessary, with reported values in the literature ranging from 20 to >50 mm [25,48]. When the proximal landing zone approaches or overlaps the origin of the left subclavian artery, there is an increased possibility of endoleak; in such cases, embolization of the artery or vascular bypass may be considered. Several commercially available devices require a normal-caliber proximal aorta with narrow acceptable landing-zone diameter ranges; for example, a recently approved multibranch endograft system requires a proximal aortic landing-zone diameter between 24 and 30 mm, thereby severely limiting the potential patient population [49,50]. Endograft sizing is of critical importance because an undersized graft may lead to fixation and sealing compromise, with resultant type I endoleaks and graft migration. It must be anticipated that most aortas increase in diameter over time as a result of age-related change and progression of aneurysmal disease in affected patients [51].
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Thoracic Aortic Aneurysm or Dissection Treatment Planning and Follow Up. CTA may also be able to guide device selection. One complication after TEVAR is the development of a bird- beak endograft configuration in the proximal landing zone, which portends a higher risk of endoleak. This configuration results most commonly when the proximal landing zone sits within a highly curved or angulated Thoracic Aorta Interventional Planning and Follow-Up aortic arch [46]. Specially designed endografts that are less susceptible to these morphologic changes can therefore be selected when preoperative imaging identifies problematic anatomy. An important subset of TEVAR is its use in repair of pathologies involving the aortic arch. A detailed understanding of the spatial relationship of the arch vessels and the luminal changes throughout the diseased arch is required for proper patient and device selection [47]. Minimum proximal and distal landing-zone intervals are necessary, with reported values in the literature ranging from 20 to >50 mm [25,48]. When the proximal landing zone approaches or overlaps the origin of the left subclavian artery, there is an increased possibility of endoleak; in such cases, embolization of the artery or vascular bypass may be considered. Several commercially available devices require a normal-caliber proximal aorta with narrow acceptable landing-zone diameter ranges; for example, a recently approved multibranch endograft system requires a proximal aortic landing-zone diameter between 24 and 30 mm, thereby severely limiting the potential patient population [49,50]. Endograft sizing is of critical importance because an undersized graft may lead to fixation and sealing compromise, with resultant type I endoleaks and graft migration. It must be anticipated that most aortas increase in diameter over time as a result of age-related change and progression of aneurysmal disease in affected patients [51].
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Although open repair is traditionally pursued for proximal aorta pathology, endovascular stent grafting is possible in certain cases of type A dissection and proximal thoracic aortic aneurysm. A 2011 study demonstrated a 98% technical success rate for TEVAR in the treatment of 45 patients with type A dissection in which the entry tear was at least 2.5 cm from the coronary ostia [52]. Notably, transposition of the supra-aortic vessels was necessary in nearly half of the patients in this study to ensure an adequate landing zone. Other authors recommend a minimum distance of 1 cm from the intimal tear entry site to the sinotubular junction and brachiocephalic trunk [11]. CTA is essential in planning for these cases to avert compromise of coronary and brachiocephalic circulation as well as aortic valve dysfunction. An essential aspect of pre-TEVAR planning is evaluation of the iliofemoral vasculature. Thoracic aorta endografts tend to be larger than their abdominal counterparts, requiring insertion sheaths with outer diameters up to 27 French. For this reason, a minimum vessel diameter of at least 8 to 9 mm is preferred [25,26]. Additionally, increased vessel depth, degree of femoral artery calcification, and iliofemoral tortuosity have been shown to be negative predictors of percutaneous TEVAR success [24]. All of these variables are readily evaluable with CTA and, in conjunction with sound clinical judgment, can be used to avoid the dreaded complication of iliac disruption necessitating open surgical repair. In cases of unfavorable anatomy, surgical or endovascular conduits have been shown to reliably facilitate endovascular repair [53]. The radiation dose associated with properly performed CT examinations in the evaluation of thoracic aortic disease is not of significant concern [54].
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Thoracic Aortic Aneurysm or Dissection Treatment Planning and Follow Up. Although open repair is traditionally pursued for proximal aorta pathology, endovascular stent grafting is possible in certain cases of type A dissection and proximal thoracic aortic aneurysm. A 2011 study demonstrated a 98% technical success rate for TEVAR in the treatment of 45 patients with type A dissection in which the entry tear was at least 2.5 cm from the coronary ostia [52]. Notably, transposition of the supra-aortic vessels was necessary in nearly half of the patients in this study to ensure an adequate landing zone. Other authors recommend a minimum distance of 1 cm from the intimal tear entry site to the sinotubular junction and brachiocephalic trunk [11]. CTA is essential in planning for these cases to avert compromise of coronary and brachiocephalic circulation as well as aortic valve dysfunction. An essential aspect of pre-TEVAR planning is evaluation of the iliofemoral vasculature. Thoracic aorta endografts tend to be larger than their abdominal counterparts, requiring insertion sheaths with outer diameters up to 27 French. For this reason, a minimum vessel diameter of at least 8 to 9 mm is preferred [25,26]. Additionally, increased vessel depth, degree of femoral artery calcification, and iliofemoral tortuosity have been shown to be negative predictors of percutaneous TEVAR success [24]. All of these variables are readily evaluable with CTA and, in conjunction with sound clinical judgment, can be used to avoid the dreaded complication of iliac disruption necessitating open surgical repair. In cases of unfavorable anatomy, surgical or endovascular conduits have been shown to reliably facilitate endovascular repair [53]. The radiation dose associated with properly performed CT examinations in the evaluation of thoracic aortic disease is not of significant concern [54].
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Potential nephrotoxicity from iodinated contrast in patients with impaired renal function is the primary concern in this patient population, although the benefits of obtaining key diagnostic information typically outweigh the low risk of developing contrast-induced nephropathy [55]. Utilization of modern CT optimization techniques, such as high-pitch spiral CT imaging, low kilovolt (peak) imaging, wide-area detectors, and iterative reconstruction techniques, allows for lower volumes of contrast and lower radiation dose with adequate diagnostic image quality [39,56,57]. CT CT Unenhanced CT is useful for identification of aortic size, acute IMH, and aortic calcification. In conjunction with CTA, sensitivity for detection of IMH is as high as 96%, and sensitivity and specificity for detection of the intimal flap in aortic dissection approach 100% [11,39]. Moreover, unenhanced CT can delineate complications related to acute aortic syndromes such as mediastinal or pericardial hemorrhage and rupture. The addition of CTA allows for comprehensive assessment of other sequelae, including end-organ ischemia, acute aortic valvular insufficiency, intravascular thrombus, and supra-aortic, coronary, and mesenteric vascular involvement [25,39,58]. The use of contrast-enhanced CT and multiphase CT (without and with contrast) can provide similar information to CTA with regard to the anatomic extent of vascular pathology. Often, such studies are pursued to investigate other clinical questions or vague presentations and incidentally reveal significant vascular findings in the thoracic aorta. The lack of standard thin-section image acquisition, arterial-phase bolus timing, and 3-D renderings with these techniques is the principal limitation, and therefore CTA is the preferred imaging modality for the dedicated workup of thoracic aorta diseases [37,39].
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Thoracic Aortic Aneurysm or Dissection Treatment Planning and Follow Up. Potential nephrotoxicity from iodinated contrast in patients with impaired renal function is the primary concern in this patient population, although the benefits of obtaining key diagnostic information typically outweigh the low risk of developing contrast-induced nephropathy [55]. Utilization of modern CT optimization techniques, such as high-pitch spiral CT imaging, low kilovolt (peak) imaging, wide-area detectors, and iterative reconstruction techniques, allows for lower volumes of contrast and lower radiation dose with adequate diagnostic image quality [39,56,57]. CT CT Unenhanced CT is useful for identification of aortic size, acute IMH, and aortic calcification. In conjunction with CTA, sensitivity for detection of IMH is as high as 96%, and sensitivity and specificity for detection of the intimal flap in aortic dissection approach 100% [11,39]. Moreover, unenhanced CT can delineate complications related to acute aortic syndromes such as mediastinal or pericardial hemorrhage and rupture. The addition of CTA allows for comprehensive assessment of other sequelae, including end-organ ischemia, acute aortic valvular insufficiency, intravascular thrombus, and supra-aortic, coronary, and mesenteric vascular involvement [25,39,58]. The use of contrast-enhanced CT and multiphase CT (without and with contrast) can provide similar information to CTA with regard to the anatomic extent of vascular pathology. Often, such studies are pursued to investigate other clinical questions or vague presentations and incidentally reveal significant vascular findings in the thoracic aorta. The lack of standard thin-section image acquisition, arterial-phase bolus timing, and 3-D renderings with these techniques is the principal limitation, and therefore CTA is the preferred imaging modality for the dedicated workup of thoracic aorta diseases [37,39].
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Thoracic Aorta Interventional Planning and Follow-Up MRA Similar to CT, magnetic resonance imaging (MRI) of the thoracic aorta can be performed with and without intravenous contrast. The principle advantage of MRI over CT is the lack of ionizing radiation, making it a particularly attractive imaging option in young patients. MRI is a more time-consuming study than CT, necessitating a stable patient. Importantly, MRI confers similar sensitivity and specificity as CTA and transesophageal echocardiography (TEE) for detection of dissection flaps, although like TEE it is less accurate for detection of branch vessel involvement [59]. There are a variety of unenhanced MRA techniques, including time of flight, phase-contrast imaging, ECG-gated fast spin-echo, and steady-state free precession (SSFP). SSFP, for example, has been shown to have equal accuracy for the assessment of aortic diameter compared with contrast-enhanced MRA (CE-MRA) [60]. The SSFP technique is also useful for visualization of dissection flaps [39]. General limitations with unenhanced MRA include loss of signal due to turbulent flow, long acquisition times, susceptibility to field inhomogeneity and motion, and the need for considerable patient cooperation for sequences requiring breath holding [36]. CE-MRA using 3-D spoiled gradient-echo sequences is the preferred MRI technique for thoracic aortic imaging, providing superior arterial signal, high spatial and contrast resolution, and rapid data acquisition during a single breath hold [36,39]. ECG gating may be added for motion-free evaluation of the ascending aorta and aortic root. Similar to the typical multiphasic CTA protocol, CE-MRA studies generally consist of unenhanced, arterial, and delayed-phase images. Various triggering methods can be used to ensure adequate gadolinium contrast opacification.
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Thoracic Aortic Aneurysm or Dissection Treatment Planning and Follow Up. Thoracic Aorta Interventional Planning and Follow-Up MRA Similar to CT, magnetic resonance imaging (MRI) of the thoracic aorta can be performed with and without intravenous contrast. The principle advantage of MRI over CT is the lack of ionizing radiation, making it a particularly attractive imaging option in young patients. MRI is a more time-consuming study than CT, necessitating a stable patient. Importantly, MRI confers similar sensitivity and specificity as CTA and transesophageal echocardiography (TEE) for detection of dissection flaps, although like TEE it is less accurate for detection of branch vessel involvement [59]. There are a variety of unenhanced MRA techniques, including time of flight, phase-contrast imaging, ECG-gated fast spin-echo, and steady-state free precession (SSFP). SSFP, for example, has been shown to have equal accuracy for the assessment of aortic diameter compared with contrast-enhanced MRA (CE-MRA) [60]. The SSFP technique is also useful for visualization of dissection flaps [39]. General limitations with unenhanced MRA include loss of signal due to turbulent flow, long acquisition times, susceptibility to field inhomogeneity and motion, and the need for considerable patient cooperation for sequences requiring breath holding [36]. CE-MRA using 3-D spoiled gradient-echo sequences is the preferred MRI technique for thoracic aortic imaging, providing superior arterial signal, high spatial and contrast resolution, and rapid data acquisition during a single breath hold [36,39]. ECG gating may be added for motion-free evaluation of the ascending aorta and aortic root. Similar to the typical multiphasic CTA protocol, CE-MRA studies generally consist of unenhanced, arterial, and delayed-phase images. Various triggering methods can be used to ensure adequate gadolinium contrast opacification.
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Thoracic Aortic Aneurysm or Dissection Treatment Planning and Follow Up
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Because the images are acquired in a near-isotropic fashion, similar multiplanar reformats to those used in CTA can be produced [39]. In addition to characterizing the extent of aortic pathology and providing precise, highly reproducible aortic measurements, CE-MRA has particular efficacy in delineation of mural thrombus versus intramural blood when CT results are equivocal [10,61]. It is also useful in the differentiation of aortic wall inflammation from intramural hemorrhage and atheroma [36]. A point of caution in the interpretation of MRA is to use source images for measurements, as maximum-intenstiy projection images may obscure the vessel wall and lead to underestimation of lumen size [10]. More advanced magnetic resonance (MR) applications allow flow mapping via time-resolved imaging techniques. Such techniques allow for the evaluation of abnormal vascular anatomy, atherosclerotic plaque burden, collateral blood flow, and hemodynamic parameters in the involved segment of aorta [36,39]. Although CE-MRA is preferred for the aforementioned reasons, certain situations exist in which unenhanced MRA is desirable. These include patients with poor intravenous access; advanced, dialysis-dependent renal failure with glomerular filtration rate <30 mL/min/1.73 m2 (because of the risk of nephrogenic systemic fibrosis); and pregnancy (because of the possible teratogenic effects of gadolinium-based contrast agents) [55,60,62]. Aortography Catheter angiography has largely been replaced by cross-sectional imaging in the evaluation of patients with suspected aortic pathology. An exception is in cases of coexisting malperfusion involving the coronary, visceral, or cerebral circulations. In such cases, angiography allows for evaluation and possible revascularization of the affected vascular bed along with further characterization of aortic pathology [45,61,63].
|
Thoracic Aortic Aneurysm or Dissection Treatment Planning and Follow Up. Because the images are acquired in a near-isotropic fashion, similar multiplanar reformats to those used in CTA can be produced [39]. In addition to characterizing the extent of aortic pathology and providing precise, highly reproducible aortic measurements, CE-MRA has particular efficacy in delineation of mural thrombus versus intramural blood when CT results are equivocal [10,61]. It is also useful in the differentiation of aortic wall inflammation from intramural hemorrhage and atheroma [36]. A point of caution in the interpretation of MRA is to use source images for measurements, as maximum-intenstiy projection images may obscure the vessel wall and lead to underestimation of lumen size [10]. More advanced magnetic resonance (MR) applications allow flow mapping via time-resolved imaging techniques. Such techniques allow for the evaluation of abnormal vascular anatomy, atherosclerotic plaque burden, collateral blood flow, and hemodynamic parameters in the involved segment of aorta [36,39]. Although CE-MRA is preferred for the aforementioned reasons, certain situations exist in which unenhanced MRA is desirable. These include patients with poor intravenous access; advanced, dialysis-dependent renal failure with glomerular filtration rate <30 mL/min/1.73 m2 (because of the risk of nephrogenic systemic fibrosis); and pregnancy (because of the possible teratogenic effects of gadolinium-based contrast agents) [55,60,62]. Aortography Catheter angiography has largely been replaced by cross-sectional imaging in the evaluation of patients with suspected aortic pathology. An exception is in cases of coexisting malperfusion involving the coronary, visceral, or cerebral circulations. In such cases, angiography allows for evaluation and possible revascularization of the affected vascular bed along with further characterization of aortic pathology [45,61,63].
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3099659
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acrac_3099659_12
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Thoracic Aortic Aneurysm or Dissection Treatment Planning and Follow Up
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Angiography has gained traction in the hybrid operating-room approach to acute type A aortic dissection, in which diagnostic and interventional angiography techniques are combined with open surgical repair [63]. Catheter angiography allows for assessment of luminal size of the iliofemoral system but is limited in its ability to assess for atherosclerotic plaque burden [56]. Additionally, digital subtraction angiography remains the gold standard for preintervention visualization of the artery of Adamkiewicz, an important consideration when there is high concern for spinal cord ischemia [64]. TEE and TTE In hemodynamically unstable patients, transthoracic echocardiography (TTE) is a useful imaging study for rapid evaluation of valvular function, aortic root dilation, and thoracic aortic dissection. This can be further supplemented with TEE, which allows for comparatively superior anatomic evaluation and can be left in place for intraoperative monitoring [61,65]. Although offering comparable sensitivities to CT and MRI for detection of thoracic aortic dissection, TEE is limited in its sensitivity for detection of branch vessel involvement and delineation of pathology below the gastroesophageal junction [59]. Echocardiography can also evaluate for concomitant cardiovascular disease and identify patients in whom coronary revascularization or valvular repair may be indicated [54,66]. Thoracic Aorta Interventional Planning and Follow-Up IVUS Similar to intraprocedural TEE, intravascular US (IVUS) is an additional adjunctive imaging tool that can aid in optimal visualization of intimal tears, ideal endograft positioning, assessment of branch vessel patency, and detection of abnormal flow within the false lumen and excluded aneurysm sac after endograft placement [67].
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Thoracic Aortic Aneurysm or Dissection Treatment Planning and Follow Up. Angiography has gained traction in the hybrid operating-room approach to acute type A aortic dissection, in which diagnostic and interventional angiography techniques are combined with open surgical repair [63]. Catheter angiography allows for assessment of luminal size of the iliofemoral system but is limited in its ability to assess for atherosclerotic plaque burden [56]. Additionally, digital subtraction angiography remains the gold standard for preintervention visualization of the artery of Adamkiewicz, an important consideration when there is high concern for spinal cord ischemia [64]. TEE and TTE In hemodynamically unstable patients, transthoracic echocardiography (TTE) is a useful imaging study for rapid evaluation of valvular function, aortic root dilation, and thoracic aortic dissection. This can be further supplemented with TEE, which allows for comparatively superior anatomic evaluation and can be left in place for intraoperative monitoring [61,65]. Although offering comparable sensitivities to CT and MRI for detection of thoracic aortic dissection, TEE is limited in its sensitivity for detection of branch vessel involvement and delineation of pathology below the gastroesophageal junction [59]. Echocardiography can also evaluate for concomitant cardiovascular disease and identify patients in whom coronary revascularization or valvular repair may be indicated [54,66]. Thoracic Aorta Interventional Planning and Follow-Up IVUS Similar to intraprocedural TEE, intravascular US (IVUS) is an additional adjunctive imaging tool that can aid in optimal visualization of intimal tears, ideal endograft positioning, assessment of branch vessel patency, and detection of abnormal flow within the false lumen and excluded aneurysm sac after endograft placement [67].
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3099659
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acrac_3099659_13
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Thoracic Aortic Aneurysm or Dissection Treatment Planning and Follow Up
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US In cases where thoracic aortic disease does not extend into the abdomen and no cross-sectional imaging of the iliofemoral system is available, US duplex Doppler of the iliofemoral arteries is useful for assessing adequate access. US duplex Doppler allows for assessment of vessel diameter and plaque burden along the anterior aspect of the vessel. In one recent series examining the use of US-guided femoral access in abdominal aortic endovascular aneurysm repair patients, intraoperative US guidance was shown to significantly reduce operative time and access wound complications [68]. Although similar dedicated studies are not available for TEVAR, the underlying principle is directly transferrable. Similarly, IVUS at the time of intervention has been shown to provide reliable information regarding iliofemoral morphology and atherosclerotic disease burden [56]. Radiography Chest radiographs will demonstrate abnormalities in a large percentage of patients with acute thoracic aorta pathology. For example, in patients presenting with acute aortic dissection, >80% demonstrated chest radiograph abnormalities, with mediastinal widening seen in just over 50% of cases [59,69]. However, radiography can only alert to an underlying abnormality and provides no specific information regarding type of pathology or detailed anatomic information necessary for interventional planning. FDG-PET/CT Nuclear medicine studies play a limited role in the workup of acute aortic pathology. In patients presenting with acute type B aortic dissection, greater uptake of fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG) in the aortic wall as seen on positron emission tomography (PET)/CT has been shown to predict rupture and dissection propagation [70]. The optimal CTA protocol for TEVAR follow-up is not well defined. Most commonly a triphasic protocol is performed with acquisition of unenhanced, arterial, and delayed-phase (60-120 seconds after injection) imaging.
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Thoracic Aortic Aneurysm or Dissection Treatment Planning and Follow Up. US In cases where thoracic aortic disease does not extend into the abdomen and no cross-sectional imaging of the iliofemoral system is available, US duplex Doppler of the iliofemoral arteries is useful for assessing adequate access. US duplex Doppler allows for assessment of vessel diameter and plaque burden along the anterior aspect of the vessel. In one recent series examining the use of US-guided femoral access in abdominal aortic endovascular aneurysm repair patients, intraoperative US guidance was shown to significantly reduce operative time and access wound complications [68]. Although similar dedicated studies are not available for TEVAR, the underlying principle is directly transferrable. Similarly, IVUS at the time of intervention has been shown to provide reliable information regarding iliofemoral morphology and atherosclerotic disease burden [56]. Radiography Chest radiographs will demonstrate abnormalities in a large percentage of patients with acute thoracic aorta pathology. For example, in patients presenting with acute aortic dissection, >80% demonstrated chest radiograph abnormalities, with mediastinal widening seen in just over 50% of cases [59,69]. However, radiography can only alert to an underlying abnormality and provides no specific information regarding type of pathology or detailed anatomic information necessary for interventional planning. FDG-PET/CT Nuclear medicine studies play a limited role in the workup of acute aortic pathology. In patients presenting with acute type B aortic dissection, greater uptake of fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG) in the aortic wall as seen on positron emission tomography (PET)/CT has been shown to predict rupture and dissection propagation [70]. The optimal CTA protocol for TEVAR follow-up is not well defined. Most commonly a triphasic protocol is performed with acquisition of unenhanced, arterial, and delayed-phase (60-120 seconds after injection) imaging.
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3099659
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acrac_3099659_14
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Thoracic Aortic Aneurysm or Dissection Treatment Planning and Follow Up
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The utility of the unenhanced phase is to differentiate extraluminal calcification or postendoleak intervention material from extraluminal contrast seen on contrast-enhanced images. Although comprehensive, such a protocol delivers a high radiation dose. Some institutions employ a late delayed phase of 300 seconds to better visualize low-flow endoleaks [72]. With regard to endoleak, type I endoleaks occurring at the proximal (Ia) or distal (Ib) landing zones are the most common cause for reintervention following TEVAR, occurring in up to 15% of cases [75]. In contrast to abdominal aorta endovascular repair where type II endoleaks are most common, type II endoleaks occur in a small percentage of TEVAR patients, likely because of fewer patent collateral vessels in the thorax compared with the abdomen [76]. Furthermore, type II endoleaks are not associated with increased risk of thoracic aorta rupture and are often managed conservatively. Types III, IV, and V endoleaks occur much less frequently, with type III being the only subtype other than type I to require immediate therapy [72]. Thoracic Aorta Interventional Planning and Follow-Up It has been shown that luminal diameter as determined from 3-D measurements correlates well with aortic luminal area during the postoperative period and can be used as a proxy for luminal blood flow [77]. This applies to both true and false lumens in cases of dissection, although the relationship becomes less clear with large false lumen diameters because of the propensity for complex luminal configuration. Serial evaluation of true and false lumen diameters via CTA in the postintervention period is a marker for vascular remodeling. Recent midterm results from the VIRTUE Registry demonstrate similar rates of vascular remodeling in patients with uncomplicated acute and subacute type B dissections.
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Thoracic Aortic Aneurysm or Dissection Treatment Planning and Follow Up. The utility of the unenhanced phase is to differentiate extraluminal calcification or postendoleak intervention material from extraluminal contrast seen on contrast-enhanced images. Although comprehensive, such a protocol delivers a high radiation dose. Some institutions employ a late delayed phase of 300 seconds to better visualize low-flow endoleaks [72]. With regard to endoleak, type I endoleaks occurring at the proximal (Ia) or distal (Ib) landing zones are the most common cause for reintervention following TEVAR, occurring in up to 15% of cases [75]. In contrast to abdominal aorta endovascular repair where type II endoleaks are most common, type II endoleaks occur in a small percentage of TEVAR patients, likely because of fewer patent collateral vessels in the thorax compared with the abdomen [76]. Furthermore, type II endoleaks are not associated with increased risk of thoracic aorta rupture and are often managed conservatively. Types III, IV, and V endoleaks occur much less frequently, with type III being the only subtype other than type I to require immediate therapy [72]. Thoracic Aorta Interventional Planning and Follow-Up It has been shown that luminal diameter as determined from 3-D measurements correlates well with aortic luminal area during the postoperative period and can be used as a proxy for luminal blood flow [77]. This applies to both true and false lumens in cases of dissection, although the relationship becomes less clear with large false lumen diameters because of the propensity for complex luminal configuration. Serial evaluation of true and false lumen diameters via CTA in the postintervention period is a marker for vascular remodeling. Recent midterm results from the VIRTUE Registry demonstrate similar rates of vascular remodeling in patients with uncomplicated acute and subacute type B dissections.
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3099659
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acrac_3099659_15
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Thoracic Aortic Aneurysm or Dissection Treatment Planning and Follow Up
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Along with other studies demonstrating a mortality benefit in the treatment of subacute to chronic uncomplicated type B dissections, these data suggest that TEVAR is a viable alternative treatment option in the management of these patients compared with optimized medical therapy [12,33,34,78]. Partial false lumen thrombosis is an important predictor of regional luminal growth and reintervention rate. Although incompletely understood, this is postulated to be due to a regional increase in luminal pressure owing to small diameter [79]. Chronic dissections tend to show lesser degrees of remodeling, perhaps because of the frequent presence of multiple intimal tears and development of intercostal collaterals in these patients [14,80]. When there is a question of false lumen thrombosis status, the absence of contrast enhancement on arterial and early delayed-phase CTA does not necessarily indicate complete thrombosis given the possibility of a low-flow state. In such cases, more-delayed imaging demonstrates higher sensitivity for detection of partial thrombosis [81]. Similar to the findings seen in TEVAR for aortic dissection, there is significant vascular remodeling when TEVAR is used for IMH or PAU, with near-complete normalization of aortic diameter at 1 year as measured on CTA [13,82]. CTA is also the preferred imaging modality of choice for evaluation of endograft infection, one of the most serious complications after TEVAR. A recent study demonstrated that in the small number of patients with an infected endograft, CTA suggested the diagnosis in 78% of cases, with the most common findings being periaortic inflammation and erosion into surrounding structures [83]. The principle disadvantages of CTA in the follow-up period are potential nephrotoxicity and cumulative radiation dose, particularly in younger patients.
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Thoracic Aortic Aneurysm or Dissection Treatment Planning and Follow Up. Along with other studies demonstrating a mortality benefit in the treatment of subacute to chronic uncomplicated type B dissections, these data suggest that TEVAR is a viable alternative treatment option in the management of these patients compared with optimized medical therapy [12,33,34,78]. Partial false lumen thrombosis is an important predictor of regional luminal growth and reintervention rate. Although incompletely understood, this is postulated to be due to a regional increase in luminal pressure owing to small diameter [79]. Chronic dissections tend to show lesser degrees of remodeling, perhaps because of the frequent presence of multiple intimal tears and development of intercostal collaterals in these patients [14,80]. When there is a question of false lumen thrombosis status, the absence of contrast enhancement on arterial and early delayed-phase CTA does not necessarily indicate complete thrombosis given the possibility of a low-flow state. In such cases, more-delayed imaging demonstrates higher sensitivity for detection of partial thrombosis [81]. Similar to the findings seen in TEVAR for aortic dissection, there is significant vascular remodeling when TEVAR is used for IMH or PAU, with near-complete normalization of aortic diameter at 1 year as measured on CTA [13,82]. CTA is also the preferred imaging modality of choice for evaluation of endograft infection, one of the most serious complications after TEVAR. A recent study demonstrated that in the small number of patients with an infected endograft, CTA suggested the diagnosis in 78% of cases, with the most common findings being periaortic inflammation and erosion into surrounding structures [83]. The principle disadvantages of CTA in the follow-up period are potential nephrotoxicity and cumulative radiation dose, particularly in younger patients.
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3099659
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acrac_3099659_16
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Thoracic Aortic Aneurysm or Dissection Treatment Planning and Follow Up
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A study evaluating radiation exposure during TEVAR and subsequent follow-up found that cumulative lifetime radiation exposure in these patients is likely to exceed 350 mSv, conferring an increased lifetime risk of at least 2.7% for developing solid-organ malignancy or leukemia [84]. The development of ever-advanced iterative reconstruction algorithms permits the use of lower tube energies, thereby allowing for reduced patient radiation exposure. A recent study highlighted radiation dose reductions ranging from 63% to 69% at standard kilovolt (peak) using a fully iterative reconstruction algorithm as compared with standard filtered back-projection without appreciable changes in conspicuity of endoleaks or in-stent thrombosis [85]. Dual-energy acquisition offers the possibility of eliminating the unenhanced phase via the creation of a virtual noncontrast image set. Another recent study demonstrated near-perfect correlation between single- and dual-phase dual-energy scans in comparison with a traditional three-phase protocol, with 19.5% and 64.1% less radiation exposure, respectively [72]. CT CT Although not ideal given the inability to directly detect endoleaks, unenhanced CT can still offer valuable follow- up information in TEVAR patients with chronic renal insufficiency and stent grafts not amenable to MRA. Unenhanced CT is useful in the assessment of graft migration, aortic rupture, and delineation of vascular calcifications, hematoma, and surgical material that could otherwise be confused for endoleak on CTA examinations [36]. Additionally, by using aneurysm sac diameter as a proxy for graft and anastomotic integrity, unenhanced CT can indirectly suggest endoleak if sac volume increases over time by more than 2% [86]. In patients with stable findings on early postintervention imaging and a low risk of graft complications, follow-up with unenhanced CT complemented by CTA when questions arise may be a viable strategy.
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Thoracic Aortic Aneurysm or Dissection Treatment Planning and Follow Up. A study evaluating radiation exposure during TEVAR and subsequent follow-up found that cumulative lifetime radiation exposure in these patients is likely to exceed 350 mSv, conferring an increased lifetime risk of at least 2.7% for developing solid-organ malignancy or leukemia [84]. The development of ever-advanced iterative reconstruction algorithms permits the use of lower tube energies, thereby allowing for reduced patient radiation exposure. A recent study highlighted radiation dose reductions ranging from 63% to 69% at standard kilovolt (peak) using a fully iterative reconstruction algorithm as compared with standard filtered back-projection without appreciable changes in conspicuity of endoleaks or in-stent thrombosis [85]. Dual-energy acquisition offers the possibility of eliminating the unenhanced phase via the creation of a virtual noncontrast image set. Another recent study demonstrated near-perfect correlation between single- and dual-phase dual-energy scans in comparison with a traditional three-phase protocol, with 19.5% and 64.1% less radiation exposure, respectively [72]. CT CT Although not ideal given the inability to directly detect endoleaks, unenhanced CT can still offer valuable follow- up information in TEVAR patients with chronic renal insufficiency and stent grafts not amenable to MRA. Unenhanced CT is useful in the assessment of graft migration, aortic rupture, and delineation of vascular calcifications, hematoma, and surgical material that could otherwise be confused for endoleak on CTA examinations [36]. Additionally, by using aneurysm sac diameter as a proxy for graft and anastomotic integrity, unenhanced CT can indirectly suggest endoleak if sac volume increases over time by more than 2% [86]. In patients with stable findings on early postintervention imaging and a low risk of graft complications, follow-up with unenhanced CT complemented by CTA when questions arise may be a viable strategy.
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3099659
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acrac_3099659_17
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Thoracic Aortic Aneurysm or Dissection Treatment Planning and Follow Up
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MRA MRA MRI after TEVAR suffers from severe susceptibility to artifacts relating to the stainless steel used in many stent graft types, obscuring surrounding relevant anatomy and limiting evaluation for endoleak [39,84]. One particular Thoracic Aorta Interventional Planning and Follow-Up group in which MRI is a preferred imaging modality is patients in whom nitinol stents are placed. This is because these endografts do not produce susceptibility artifacts, thereby allowing adequate visualization of the underlying vasculature [74]. Various studies have demonstrated comparable to superior sensitivities in detection of endoleak with MRA compared with CTA when such stents are used [87,88]. Additional research has shown that in patients with MR-compatible endografts, unenhanced MRA can reliably assess stent position and geometry, whereas CE- MRA can sufficiently evaluate endograft hemodynamics and aortic diameter [89]. A principal advantage of MRI in the follow-up period is its lack of ionizing radiation. In younger patients in whom cumulative radiation dose from repeat CT examinations is of particular concern, placement of an MR- compatible endograft should strongly be considered so that routine MRI surveillance can be obtained [61]. As noted previously, the use of CE-MRA is limited in cases of severe renal dysfunction and pregnancy. Aortography Given its invasiveness, catheter angiography is not a routine surveillance tool after TEVAR. However, in cases where significant endoleaks are identified on cross-sectional imaging or where the origin of endoleak is unclear, catheter angiography is indispensable for further anatomic characterization as well as definitive treatment [76]. TEE and TTE In cases where the extent of residual aortopathy is confined to the aortic root or proximal aorta dilation, TTE may play an adjunctive surveillance role, reducing the frequency of CT or MR surveillance [61].
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Thoracic Aortic Aneurysm or Dissection Treatment Planning and Follow Up. MRA MRA MRI after TEVAR suffers from severe susceptibility to artifacts relating to the stainless steel used in many stent graft types, obscuring surrounding relevant anatomy and limiting evaluation for endoleak [39,84]. One particular Thoracic Aorta Interventional Planning and Follow-Up group in which MRI is a preferred imaging modality is patients in whom nitinol stents are placed. This is because these endografts do not produce susceptibility artifacts, thereby allowing adequate visualization of the underlying vasculature [74]. Various studies have demonstrated comparable to superior sensitivities in detection of endoleak with MRA compared with CTA when such stents are used [87,88]. Additional research has shown that in patients with MR-compatible endografts, unenhanced MRA can reliably assess stent position and geometry, whereas CE- MRA can sufficiently evaluate endograft hemodynamics and aortic diameter [89]. A principal advantage of MRI in the follow-up period is its lack of ionizing radiation. In younger patients in whom cumulative radiation dose from repeat CT examinations is of particular concern, placement of an MR- compatible endograft should strongly be considered so that routine MRI surveillance can be obtained [61]. As noted previously, the use of CE-MRA is limited in cases of severe renal dysfunction and pregnancy. Aortography Given its invasiveness, catheter angiography is not a routine surveillance tool after TEVAR. However, in cases where significant endoleaks are identified on cross-sectional imaging or where the origin of endoleak is unclear, catheter angiography is indispensable for further anatomic characterization as well as definitive treatment [76]. TEE and TTE In cases where the extent of residual aortopathy is confined to the aortic root or proximal aorta dilation, TTE may play an adjunctive surveillance role, reducing the frequency of CT or MR surveillance [61].
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3099659
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acrac_3099659_18
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Thoracic Aortic Aneurysm or Dissection Treatment Planning and Follow Up
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TEE provides suboptimal evaluation of suspected endoleak and should be considered only in patients in whom CTA is precluded because of severe renal dysfunction or contrast allergy [84]. US US US duplex Doppler is an alternative modality for follow-up of abdominal aortic endovascular aneurysm repair with high specificity for detection of endoleaks and high accuracy for evaluation of aneurysm sac size. The addition of contrast material makes US an even more sensitive and specific test than CTA for characterization of endoleaks [90]. Its use in TEVAR is impractical in the chest given poor acoustic windows but may provide diagnostic information for the abdominal aspect of the stent graft [38]. Radiography Radiography in the postintervention period has traditionally been used to evaluate for stent migration and integrity [71]. However, given ever-increasing improvements in CT imaging quality as well as the low incidence of stent graft fractures with currently available endograft devices, the utility of radiographic follow-up is increasingly limited [38]. surveillance interval is unclear and may be procedure and patient specific. In the postintervention follow-up evaluation, CTA is the imaging modality of choice, given its sensitivity for the detection of endoleaks, changes in aortic/aneurysm diameter, evaluation of false lumen thrombosis, and Thoracic Aorta Interventional Planning and Follow-Up assessment for device migration and integrity. MRA can provide equivalent information and is preferred for long-term follow-up of younger patients given the lack of ionizing radiation, but it can be used only with MR- compatible stent grafts. Although there are references that report on studies with design limitations, 37 well-designed or good-quality studies provide good evidence. Relative Radiation Level Designations 30-100 mSv 10-30 mSv
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Thoracic Aortic Aneurysm or Dissection Treatment Planning and Follow Up. TEE provides suboptimal evaluation of suspected endoleak and should be considered only in patients in whom CTA is precluded because of severe renal dysfunction or contrast allergy [84]. US US US duplex Doppler is an alternative modality for follow-up of abdominal aortic endovascular aneurysm repair with high specificity for detection of endoleaks and high accuracy for evaluation of aneurysm sac size. The addition of contrast material makes US an even more sensitive and specific test than CTA for characterization of endoleaks [90]. Its use in TEVAR is impractical in the chest given poor acoustic windows but may provide diagnostic information for the abdominal aspect of the stent graft [38]. Radiography Radiography in the postintervention period has traditionally been used to evaluate for stent migration and integrity [71]. However, given ever-increasing improvements in CT imaging quality as well as the low incidence of stent graft fractures with currently available endograft devices, the utility of radiographic follow-up is increasingly limited [38]. surveillance interval is unclear and may be procedure and patient specific. In the postintervention follow-up evaluation, CTA is the imaging modality of choice, given its sensitivity for the detection of endoleaks, changes in aortic/aneurysm diameter, evaluation of false lumen thrombosis, and Thoracic Aorta Interventional Planning and Follow-Up assessment for device migration and integrity. MRA can provide equivalent information and is preferred for long-term follow-up of younger patients given the lack of ionizing radiation, but it can be used only with MR- compatible stent grafts. Although there are references that report on studies with design limitations, 37 well-designed or good-quality studies provide good evidence. Relative Radiation Level Designations 30-100 mSv 10-30 mSv
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3099659
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acrac_69481_0
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Head Trauma PCAs
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Introduction/Background Head trauma (ie, head injury) is a significant public health concern and is a leading cause of morbidity and mortality in children and young adults. According to the Centers for Disease Control and Prevention, head trauma resulted in over 2.5 million emergency department (ED) visits in the United States in 2014 (63% increase from 2006) with nearly 290,000 hospitalizations and 57,000 deaths [1]. Common mechanisms of injury include falls, motor vehicle accidents, and acts of violence. Athletic and military personnel are additionally susceptible to sport- and blast- related exposures. Many individuals seek medical attention after a disruption in the normal function of the brain (eg, concussions with transient loss of consciousness [LOC] or post-traumatic amnesia [PTA]); these cases would meet the definition of a traumatic brain injury (TBI). OR aUniformed Services University, Bethesda, MarylandbPanel Chair, Montefiore Medical Center, Bronx, New York. cOhio State University, Columbus, Ohio. dDuke University School of Medicine, Durham, North Carolina; American College of Emergency Physicians. eOttawa Hospital Research Institute and the Department of Radiology, The University of Ottawa, Ottawa, Ontario, Canada; Canadian Association of Radiologists. fMayo Clinic, Rochester, Minnesota. gUniversity of New Mexico, Albuquerque, New Mexico; American College of Physicians. hUniversity of California Los Angeles, Los Angeles, California. iEinstein Healthcare Network, Philadelphia, Pennsylvania. jUniversity of California Los Angeles, Los Angeles, California; American Academy of Neurology. kOregon Health & Science University, Portland, Oregon. lLittleton Adventist Hospital, Littleton, Colorado; Neurosurgery expert. mR. Adams Cowley Shock Trauma Center, University of Maryland Medical Center, Baltimore, Maryland. nJohn H. Stroger, Jr. Hospital of Cook County, Chicago, Illinois; Neurosurgery expert.
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Head Trauma PCAs. Introduction/Background Head trauma (ie, head injury) is a significant public health concern and is a leading cause of morbidity and mortality in children and young adults. According to the Centers for Disease Control and Prevention, head trauma resulted in over 2.5 million emergency department (ED) visits in the United States in 2014 (63% increase from 2006) with nearly 290,000 hospitalizations and 57,000 deaths [1]. Common mechanisms of injury include falls, motor vehicle accidents, and acts of violence. Athletic and military personnel are additionally susceptible to sport- and blast- related exposures. Many individuals seek medical attention after a disruption in the normal function of the brain (eg, concussions with transient loss of consciousness [LOC] or post-traumatic amnesia [PTA]); these cases would meet the definition of a traumatic brain injury (TBI). OR aUniformed Services University, Bethesda, MarylandbPanel Chair, Montefiore Medical Center, Bronx, New York. cOhio State University, Columbus, Ohio. dDuke University School of Medicine, Durham, North Carolina; American College of Emergency Physicians. eOttawa Hospital Research Institute and the Department of Radiology, The University of Ottawa, Ottawa, Ontario, Canada; Canadian Association of Radiologists. fMayo Clinic, Rochester, Minnesota. gUniversity of New Mexico, Albuquerque, New Mexico; American College of Physicians. hUniversity of California Los Angeles, Los Angeles, California. iEinstein Healthcare Network, Philadelphia, Pennsylvania. jUniversity of California Los Angeles, Los Angeles, California; American Academy of Neurology. kOregon Health & Science University, Portland, Oregon. lLittleton Adventist Hospital, Littleton, Colorado; Neurosurgery expert. mR. Adams Cowley Shock Trauma Center, University of Maryland Medical Center, Baltimore, Maryland. nJohn H. Stroger, Jr. Hospital of Cook County, Chicago, Illinois; Neurosurgery expert.
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69481
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acrac_69481_1
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Head Trauma PCAs
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oAlbert Einstein College of Medicine Montefiore Medical Center, Bronx, New York, Internal Medicine Physician. pWeill Cornell Medicine, New York, New York. qColumbia University Medical Center, New York, New York. rUniversity of Cincinnati Medical Center, Cincinnati, Ohio. sSpecialty Chair, Atlanta VA Health Care System and Emory University, Atlanta, Georgia. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through representation of such organizations on expert panels. Participation on the expert panel does not necessarily imply endorsement of the final document by individual contributors or their respective organization. *The views expressed in this manuscript are those of the author and do not reflect the official policy of the Department of the Army/Navy/Air Force, Department of Defense, or United States Government. Reprint requests to: [email protected] Arteriography Cervicocerebral There is no relevant literature to support the use of catheter angiography in the initial imaging evaluation of acute head trauma. Head Trauma CTA Head and Neck There is no relevant literature to support the use of CT angiography (CTA) in the initial imaging evaluation of acute head trauma without suspected vascular injury (see Variants 8 and 9 when suspected). FDG-PET/CT Brain There is no relevant literature to support the use of fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG)-PET/CT in the initial imaging evaluation of acute head trauma. HMPAO SPECT or SPECT/CT Brain There is no relevant literature to support the use of hexamethylpropyleneamine oxime (HMPAO) single-photon emission computed tomography (SPECT) or SPECT/CT in the initial imaging evaluation of acute head trauma. MR Spectroscopy Head There is no relevant literature to support the use of MR spectroscopy (MRS) in the initial imaging evaluation of acute head trauma.
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Head Trauma PCAs. oAlbert Einstein College of Medicine Montefiore Medical Center, Bronx, New York, Internal Medicine Physician. pWeill Cornell Medicine, New York, New York. qColumbia University Medical Center, New York, New York. rUniversity of Cincinnati Medical Center, Cincinnati, Ohio. sSpecialty Chair, Atlanta VA Health Care System and Emory University, Atlanta, Georgia. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through representation of such organizations on expert panels. Participation on the expert panel does not necessarily imply endorsement of the final document by individual contributors or their respective organization. *The views expressed in this manuscript are those of the author and do not reflect the official policy of the Department of the Army/Navy/Air Force, Department of Defense, or United States Government. Reprint requests to: [email protected] Arteriography Cervicocerebral There is no relevant literature to support the use of catheter angiography in the initial imaging evaluation of acute head trauma. Head Trauma CTA Head and Neck There is no relevant literature to support the use of CT angiography (CTA) in the initial imaging evaluation of acute head trauma without suspected vascular injury (see Variants 8 and 9 when suspected). FDG-PET/CT Brain There is no relevant literature to support the use of fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG)-PET/CT in the initial imaging evaluation of acute head trauma. HMPAO SPECT or SPECT/CT Brain There is no relevant literature to support the use of hexamethylpropyleneamine oxime (HMPAO) single-photon emission computed tomography (SPECT) or SPECT/CT in the initial imaging evaluation of acute head trauma. MR Spectroscopy Head There is no relevant literature to support the use of MR spectroscopy (MRS) in the initial imaging evaluation of acute head trauma.
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69481
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acrac_69481_2
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Head Trauma PCAs
|
MRA Head and Neck There is no relevant literature to support the use of MR angiography (MRA) in the initial imaging evaluation of acute head trauma. MRI Functional (fMRI) Head There is no relevant literature to support the use of functional MRI (fMRI) in the initial imaging evaluation of acute head trauma. MRI Head There is no relevant literature to support the use of MRI in the initial imaging evaluation of acute head trauma (please see Variant 4 for discussion of MRI after negative head CT). MRI Head with DTI There is no relevant literature to support the use of diffusion tensor imaging (DTI) in the initial imaging evaluation of acute head trauma. Radiography Skull There is no relevant literature to support the use of radiographs in the initial imaging evaluation of acute head trauma (replaced by CT, which is more sensitive for neurosurgical lesions). Arteriography Cervicocerebral There is no relevant literature to support the use of catheter angiography in the initial imaging evaluation of acute head trauma. Head Trauma military personnel, per Department of Defense guidelines, a positive CT would prompt reclassification from mild to moderate TBI [18]. In the vast majority of these patients, CT will be negative for acute traumatic findings, so patients can be safely discharged rather than admitted as long as the neurologic examination is also normal (negative predictive value of 100% for neurologic deterioration requiring surgical intervention) [19]. One analysis quantified the risk of deterioration with both normal CT and neurologic examination as very low (0.006%), recommending discharge regardless of whether there was a responsible adult available to observe the patient [7]. It is important for mild TBI discharge instructions to be provided in written form; they should discuss why or when to return to the ED, plus educational information on postconcussive symptoms [20].
|
Head Trauma PCAs. MRA Head and Neck There is no relevant literature to support the use of MR angiography (MRA) in the initial imaging evaluation of acute head trauma. MRI Functional (fMRI) Head There is no relevant literature to support the use of functional MRI (fMRI) in the initial imaging evaluation of acute head trauma. MRI Head There is no relevant literature to support the use of MRI in the initial imaging evaluation of acute head trauma (please see Variant 4 for discussion of MRI after negative head CT). MRI Head with DTI There is no relevant literature to support the use of diffusion tensor imaging (DTI) in the initial imaging evaluation of acute head trauma. Radiography Skull There is no relevant literature to support the use of radiographs in the initial imaging evaluation of acute head trauma (replaced by CT, which is more sensitive for neurosurgical lesions). Arteriography Cervicocerebral There is no relevant literature to support the use of catheter angiography in the initial imaging evaluation of acute head trauma. Head Trauma military personnel, per Department of Defense guidelines, a positive CT would prompt reclassification from mild to moderate TBI [18]. In the vast majority of these patients, CT will be negative for acute traumatic findings, so patients can be safely discharged rather than admitted as long as the neurologic examination is also normal (negative predictive value of 100% for neurologic deterioration requiring surgical intervention) [19]. One analysis quantified the risk of deterioration with both normal CT and neurologic examination as very low (0.006%), recommending discharge regardless of whether there was a responsible adult available to observe the patient [7]. It is important for mild TBI discharge instructions to be provided in written form; they should discuss why or when to return to the ED, plus educational information on postconcussive symptoms [20].
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69481
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acrac_69481_3
|
Head Trauma PCAs
|
CTA Head and Neck There is no relevant literature to support the use of CTA in the initial imaging evaluation of acute head trauma without suspected vascular injury (see Variants 8 and 9 when suspected). FDG-PET/CT Brain There is no relevant literature to support the use of FDG-PET/CT in the initial imaging evaluation of acute head trauma. HMPAO SPECT or SPECT/CT Brain There is no relevant literature to support the use of SPECT in the initial imaging evaluation of acute head trauma. MR Spectroscopy Head There is no relevant literature to support the use of MRS in the initial imaging evaluation of acute head trauma. MRA Head and Neck There is no relevant literature to support the use of MRA in the initial imaging evaluation of acute head trauma. MRI Functional (fMRI) Head There is no relevant literature to support the use of fMRI in the initial imaging evaluation of acute head trauma. MRI Head There is no relevant literature to support the use of MRI in the initial imaging evaluation of acute head trauma (please see Variant 4 for discussion of MRI after negative head CT). MRI Head with DTI There is no relevant literature to support the use of DTI in the initial imaging evaluation of acute head trauma. Radiography Skull There is no relevant literature to support the use of radiographs in the initial imaging evaluation of acute head trauma (replaced by CT, which is more sensitive for neurosurgical lesions). Head Trauma Arteriography Cervicocerebral There is no relevant literature to support the use of catheter angiography in the initial imaging evaluation of acute head trauma. CT Head Head CT is useful for the evaluation of moderate, severe, or penetrating acute head trauma. Multiplanar reformatted images have been shown to increase diagnostic accuracy and should be included [16,17].
|
Head Trauma PCAs. CTA Head and Neck There is no relevant literature to support the use of CTA in the initial imaging evaluation of acute head trauma without suspected vascular injury (see Variants 8 and 9 when suspected). FDG-PET/CT Brain There is no relevant literature to support the use of FDG-PET/CT in the initial imaging evaluation of acute head trauma. HMPAO SPECT or SPECT/CT Brain There is no relevant literature to support the use of SPECT in the initial imaging evaluation of acute head trauma. MR Spectroscopy Head There is no relevant literature to support the use of MRS in the initial imaging evaluation of acute head trauma. MRA Head and Neck There is no relevant literature to support the use of MRA in the initial imaging evaluation of acute head trauma. MRI Functional (fMRI) Head There is no relevant literature to support the use of fMRI in the initial imaging evaluation of acute head trauma. MRI Head There is no relevant literature to support the use of MRI in the initial imaging evaluation of acute head trauma (please see Variant 4 for discussion of MRI after negative head CT). MRI Head with DTI There is no relevant literature to support the use of DTI in the initial imaging evaluation of acute head trauma. Radiography Skull There is no relevant literature to support the use of radiographs in the initial imaging evaluation of acute head trauma (replaced by CT, which is more sensitive for neurosurgical lesions). Head Trauma Arteriography Cervicocerebral There is no relevant literature to support the use of catheter angiography in the initial imaging evaluation of acute head trauma. CT Head Head CT is useful for the evaluation of moderate, severe, or penetrating acute head trauma. Multiplanar reformatted images have been shown to increase diagnostic accuracy and should be included [16,17].
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69481
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acrac_69481_4
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Head Trauma PCAs
|
Overall, a normal CT tends to be associated with better outcomes than an abnormal CT, and in one study of 72 patients without systemic injury, focal hemorrhages >4.1 mL predicted a 2-fold greater risk of a poor outcome than patients with smaller lesions [31]. In the setting of penetrating head trauma, most commonly gunshot wounds (including self-inflicted), only 10% survive to reach the hospital, where morbidity and mortality remain extremely high. CT findings associated with an especially poor prognosis include brain stem and bilateral hemispheric injuries [30]. Traditional CT scoring systems for ICH and mass effect (eg, Marshall, Rotterdam) have been shown to predict mortality in moderate to severe head trauma. The NeuroImaging Radiological Interpretation System is a more recently developed CT scoring system, which uses standardized terminology from the National Institutes of Health common data elements for TBI imaging and which offers improved prediction of clinical disposition and management in TBI patients (ie, who will need prolonged admissions or neurosurgical procedures), beyond prediction of mortality alone [32,33]. CTA Head and Neck There is no relevant literature to support the use of CTA in the initial imaging evaluation of acute head trauma without suspected vascular injury (see Variants 8 and 9 when suspected). Please refer to discussion under Variants 8 and 9 on clinical risk factors that are associated with intracranial vascular injury and would support the use of CTA/CT venography (CTV). FDG-PET/CT Brain There is no relevant literature to support the use of FDG-PET/CT in the initial imaging evaluation of acute head trauma. HMPAO SPECT or SPECT/CT Brain There is no relevant literature to support the use of SPECT in the initial imaging evaluation of acute head trauma. MR Spectroscopy Head There is no relevant literature to support the use of MRS in the initial imaging evaluation of acute head trauma.
|
Head Trauma PCAs. Overall, a normal CT tends to be associated with better outcomes than an abnormal CT, and in one study of 72 patients without systemic injury, focal hemorrhages >4.1 mL predicted a 2-fold greater risk of a poor outcome than patients with smaller lesions [31]. In the setting of penetrating head trauma, most commonly gunshot wounds (including self-inflicted), only 10% survive to reach the hospital, where morbidity and mortality remain extremely high. CT findings associated with an especially poor prognosis include brain stem and bilateral hemispheric injuries [30]. Traditional CT scoring systems for ICH and mass effect (eg, Marshall, Rotterdam) have been shown to predict mortality in moderate to severe head trauma. The NeuroImaging Radiological Interpretation System is a more recently developed CT scoring system, which uses standardized terminology from the National Institutes of Health common data elements for TBI imaging and which offers improved prediction of clinical disposition and management in TBI patients (ie, who will need prolonged admissions or neurosurgical procedures), beyond prediction of mortality alone [32,33]. CTA Head and Neck There is no relevant literature to support the use of CTA in the initial imaging evaluation of acute head trauma without suspected vascular injury (see Variants 8 and 9 when suspected). Please refer to discussion under Variants 8 and 9 on clinical risk factors that are associated with intracranial vascular injury and would support the use of CTA/CT venography (CTV). FDG-PET/CT Brain There is no relevant literature to support the use of FDG-PET/CT in the initial imaging evaluation of acute head trauma. HMPAO SPECT or SPECT/CT Brain There is no relevant literature to support the use of SPECT in the initial imaging evaluation of acute head trauma. MR Spectroscopy Head There is no relevant literature to support the use of MRS in the initial imaging evaluation of acute head trauma.
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69481
|
acrac_69481_5
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Head Trauma PCAs
|
MRA Head and Neck There is no relevant literature to support the use of MRA in the initial imaging evaluation of acute head trauma. MRI Functional (fMRI) Head There is no relevant literature to support the use of fMRI in the initial imaging evaluation of acute head trauma. MRI Head There is no relevant literature to support the use of MRI in the initial imaging evaluation of acute head trauma (please see Variant 4 for discussion of MRI after negative head CT). MRI Head with DTI There is no relevant literature to support the use of DTI in the initial imaging evaluation of acute head trauma. Radiography Skull There is no relevant literature to support the use of radiographs in the initial imaging evaluation of acute head trauma (replaced by CT, which is more sensitive for neurosurgical lesions). Head Trauma Arteriography Cervicocerebral There is no relevant literature to support the use of catheter angiography in the short-term follow-up imaging evaluation of acute head trauma. There is some controversy about the necessity, with other guidelines recommending against routine repeat CT in the presence of a normal initial CT and in the absence of neurologic deterioration [2]. A single-center 2-year retrospective study of 2,444 ED patients with head trauma of varying severity and a negative head CT (80.8% of all scans) found a very low rate (1 case or 0.04%) of intracranial complications within 72 hours. Of the discharged patients (74.1%), <1% returned to the ED and received a repeat CT (all negative). Of the admitted patients (25.9%), <10% received a repeat CT, with only one positive for a small parietal lobe contusion, which was not visible on the initial CT and did not require neurosurgical intervention [34]. There is also some controversy about the necessity of routine observation and repeat CT in head trauma patients with coagulopathy and a normal initial CT.
|
Head Trauma PCAs. MRA Head and Neck There is no relevant literature to support the use of MRA in the initial imaging evaluation of acute head trauma. MRI Functional (fMRI) Head There is no relevant literature to support the use of fMRI in the initial imaging evaluation of acute head trauma. MRI Head There is no relevant literature to support the use of MRI in the initial imaging evaluation of acute head trauma (please see Variant 4 for discussion of MRI after negative head CT). MRI Head with DTI There is no relevant literature to support the use of DTI in the initial imaging evaluation of acute head trauma. Radiography Skull There is no relevant literature to support the use of radiographs in the initial imaging evaluation of acute head trauma (replaced by CT, which is more sensitive for neurosurgical lesions). Head Trauma Arteriography Cervicocerebral There is no relevant literature to support the use of catheter angiography in the short-term follow-up imaging evaluation of acute head trauma. There is some controversy about the necessity, with other guidelines recommending against routine repeat CT in the presence of a normal initial CT and in the absence of neurologic deterioration [2]. A single-center 2-year retrospective study of 2,444 ED patients with head trauma of varying severity and a negative head CT (80.8% of all scans) found a very low rate (1 case or 0.04%) of intracranial complications within 72 hours. Of the discharged patients (74.1%), <1% returned to the ED and received a repeat CT (all negative). Of the admitted patients (25.9%), <10% received a repeat CT, with only one positive for a small parietal lobe contusion, which was not visible on the initial CT and did not require neurosurgical intervention [34]. There is also some controversy about the necessity of routine observation and repeat CT in head trauma patients with coagulopathy and a normal initial CT.
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69481
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acrac_69481_6
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Head Trauma PCAs
|
One prospective cohort study of 859 older adults (>55 years of age) with head trauma and a negative CT found a very low rate (3 cases or 0.3%) of delayed traumatic ICH within 14 days, and only 1 of the 3 cases occurred in a patient on anticoagulant or antiplatelet medication (warfarin with a positive repeat CT at 5 days) [35]. The authors conclude the risk of delayed ICH is low, even on anticoagulant or antiplatelet medication, and does not merit routine observation and repeat CT; however, the study is limited by the small number of patients in each anticoagulant and antiplatelet group. CTA Head and Neck There is no relevant literature to support the use of CTA in the short-term follow-up imaging evaluation of acute head trauma without suspected vascular injury (see Variants 8 and 9 when suspected). FDG-PET/CT Brain There is no relevant literature to support the use of FDG-PET/CT in the short-term follow-up imaging evaluation of acute head trauma. HMPAO SPECT or SPECT/CT Brain There is no relevant literature to support the use of SPECT in the short-term follow-up imaging evaluation of acute head trauma. MR Spectroscopy Head There is no relevant literature to support the use of MRS in the short-term follow-up imaging evaluation of acute head trauma. Head Trauma MRA Head and Neck There is no relevant literature to support the use of MRA in the short-term follow-up imaging evaluation of acute head trauma. MRI Functional (fMRI) Head There is no relevant literature to support the use of fMRI in the short-term follow-up imaging evaluation of acute head trauma. MRI Head Although brain MRI is not the most useful initial imaging modality for the evaluation of acute head trauma, it may be indicated as a follow-up study when there are persistent neurologic deficits that remain unexplained after the head CT [2]. MRI is more sensitive than CT for subtle findings adjacent to the calvarium or skull base (eg, small cortical contusions and subdural hematomas) [29].
|
Head Trauma PCAs. One prospective cohort study of 859 older adults (>55 years of age) with head trauma and a negative CT found a very low rate (3 cases or 0.3%) of delayed traumatic ICH within 14 days, and only 1 of the 3 cases occurred in a patient on anticoagulant or antiplatelet medication (warfarin with a positive repeat CT at 5 days) [35]. The authors conclude the risk of delayed ICH is low, even on anticoagulant or antiplatelet medication, and does not merit routine observation and repeat CT; however, the study is limited by the small number of patients in each anticoagulant and antiplatelet group. CTA Head and Neck There is no relevant literature to support the use of CTA in the short-term follow-up imaging evaluation of acute head trauma without suspected vascular injury (see Variants 8 and 9 when suspected). FDG-PET/CT Brain There is no relevant literature to support the use of FDG-PET/CT in the short-term follow-up imaging evaluation of acute head trauma. HMPAO SPECT or SPECT/CT Brain There is no relevant literature to support the use of SPECT in the short-term follow-up imaging evaluation of acute head trauma. MR Spectroscopy Head There is no relevant literature to support the use of MRS in the short-term follow-up imaging evaluation of acute head trauma. Head Trauma MRA Head and Neck There is no relevant literature to support the use of MRA in the short-term follow-up imaging evaluation of acute head trauma. MRI Functional (fMRI) Head There is no relevant literature to support the use of fMRI in the short-term follow-up imaging evaluation of acute head trauma. MRI Head Although brain MRI is not the most useful initial imaging modality for the evaluation of acute head trauma, it may be indicated as a follow-up study when there are persistent neurologic deficits that remain unexplained after the head CT [2]. MRI is more sensitive than CT for subtle findings adjacent to the calvarium or skull base (eg, small cortical contusions and subdural hematomas) [29].
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69481
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acrac_69481_7
|
Head Trauma PCAs
|
It is also more sensitive for small white matter lesions in traumatic or diffuse axonal injury (DAI). Only 10% of DAI is positive on CT because >80% of lesions are not associated with macroscopic hemorrhage and therefore have a higher chance of detection on MRI using a combination of T2-weighted, T2*-weighted, and diffusion-weighted images [18]. There is some controversy about the necessity of MRI in the acute phase. A single-center 2-year retrospective study of all TBI patients with both CT and MRI in the acute phase found MRI to be more sensitive for small intracranial lesions, especially shearing injuries (DAI), which could be of prognostic value in patients with unexplained poor GCS scores. However, none of these additional findings affected management plans in the acute phase [36]. A single-center 3-year prospective study of all TBI patients with both CT and MRI in the acute phase also found MRI to be more sensitive for subtle contusions, shearing injuries, and extra-axial hematomas (33% of cases). Once again, the additional information did not affect management in the acute phase [37]. If the clinical focus has transitioned from short-term management to long-term prognostication in the acute phase, then an early MRI may be of greater value, particularly in patients who have mild TBI with normal CTs (approximately 15% will have persistent neurocognitive sequelae at 1 year). A prospective Level 1 trauma multicenter study has found that approximately 27% of patients who have mild TBI with normal CTs show abnormalities on early MRI (eg, small cortical contusions or hemorrhagic axonal injury) and that these findings may be clinically relevant in improving prediction of 3-month outcomes [38]. There is ongoing research in the utility of blood-based biomarkers (eg, GFAP) to determine which patients who have mild TBI and negative CT were more likely to benefit from MRI [39].
|
Head Trauma PCAs. It is also more sensitive for small white matter lesions in traumatic or diffuse axonal injury (DAI). Only 10% of DAI is positive on CT because >80% of lesions are not associated with macroscopic hemorrhage and therefore have a higher chance of detection on MRI using a combination of T2-weighted, T2*-weighted, and diffusion-weighted images [18]. There is some controversy about the necessity of MRI in the acute phase. A single-center 2-year retrospective study of all TBI patients with both CT and MRI in the acute phase found MRI to be more sensitive for small intracranial lesions, especially shearing injuries (DAI), which could be of prognostic value in patients with unexplained poor GCS scores. However, none of these additional findings affected management plans in the acute phase [36]. A single-center 3-year prospective study of all TBI patients with both CT and MRI in the acute phase also found MRI to be more sensitive for subtle contusions, shearing injuries, and extra-axial hematomas (33% of cases). Once again, the additional information did not affect management in the acute phase [37]. If the clinical focus has transitioned from short-term management to long-term prognostication in the acute phase, then an early MRI may be of greater value, particularly in patients who have mild TBI with normal CTs (approximately 15% will have persistent neurocognitive sequelae at 1 year). A prospective Level 1 trauma multicenter study has found that approximately 27% of patients who have mild TBI with normal CTs show abnormalities on early MRI (eg, small cortical contusions or hemorrhagic axonal injury) and that these findings may be clinically relevant in improving prediction of 3-month outcomes [38]. There is ongoing research in the utility of blood-based biomarkers (eg, GFAP) to determine which patients who have mild TBI and negative CT were more likely to benefit from MRI [39].
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69481
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acrac_69481_8
|
Head Trauma PCAs
|
MRI Head with DTI There is no relevant literature to support the use of DTI in the short-term follow-up imaging evaluation of acute head trauma. Radiography Skull There is no relevant literature to support the use of radiographs in the short-term follow-up imaging evaluation of acute head trauma. Arteriography Cervicocerebral There is no relevant literature to support the use of catheter angiography in the short-term follow-up imaging evaluation of acute head trauma. CT Head In the presence of an abnormal initial CT and in the absence of neurologic deterioration, the decision to perform a routine repeat CT should depend on the estimated risk for subclinical progression of intracranial findings. A large systematic review and meta-analysis of 41 studies enrolling 10,501 patients with TBI suggested there is overutilization of repeat CT, which changed management in only 11.4% of patients across prospective studies and 9.6% of patients across retrospective studies (2.3% and 3.9% in a subgroup analysis of patients with mild TBI) [40]. Head Trauma Routine follow-up CT after an abnormal initial CT is supported for moderate to severe TBI and for anticoagulated patients [2]. Patients on anticoagulant or antiplatelet medication had a 3-fold increase in frequency of bleeding progression on repeat head CT (26% versus 9%) in one retrospective analysis of 508 CT-positive TBIs [41]. For patients with mild TBI and positive CT (who are not on anticoagulation), the appropriateness of routine repeat CT may depend on the size and type of intracranial findings. A retrospective review of 321 patients with mild TBI with ICH on initial CT found imaging progression in only 6% (and neurologic deterioration in only 1%). Subfrontal/temporal parenchymal contusion and volume of ICH >10 mL were imaging predictors of progression (use of anticoagulation and >65 years of age were clinical predictors).
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Head Trauma PCAs. MRI Head with DTI There is no relevant literature to support the use of DTI in the short-term follow-up imaging evaluation of acute head trauma. Radiography Skull There is no relevant literature to support the use of radiographs in the short-term follow-up imaging evaluation of acute head trauma. Arteriography Cervicocerebral There is no relevant literature to support the use of catheter angiography in the short-term follow-up imaging evaluation of acute head trauma. CT Head In the presence of an abnormal initial CT and in the absence of neurologic deterioration, the decision to perform a routine repeat CT should depend on the estimated risk for subclinical progression of intracranial findings. A large systematic review and meta-analysis of 41 studies enrolling 10,501 patients with TBI suggested there is overutilization of repeat CT, which changed management in only 11.4% of patients across prospective studies and 9.6% of patients across retrospective studies (2.3% and 3.9% in a subgroup analysis of patients with mild TBI) [40]. Head Trauma Routine follow-up CT after an abnormal initial CT is supported for moderate to severe TBI and for anticoagulated patients [2]. Patients on anticoagulant or antiplatelet medication had a 3-fold increase in frequency of bleeding progression on repeat head CT (26% versus 9%) in one retrospective analysis of 508 CT-positive TBIs [41]. For patients with mild TBI and positive CT (who are not on anticoagulation), the appropriateness of routine repeat CT may depend on the size and type of intracranial findings. A retrospective review of 321 patients with mild TBI with ICH on initial CT found imaging progression in only 6% (and neurologic deterioration in only 1%). Subfrontal/temporal parenchymal contusion and volume of ICH >10 mL were imaging predictors of progression (use of anticoagulation and >65 years of age were clinical predictors).
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69481
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acrac_69481_9
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Head Trauma PCAs
|
Based on outcomes analysis, the authors conclude that patients with mild TBI with a small convexity contusion or extra-axial hemorrhage <10 mL do not require routine repeat CT or admission to the intensive care unit in the absence of neurologic deterioration [42]. In the presence of an abnormal initial CT, other patient factors such as intoxication or pharmacologic sedation often affect the reliability of serial examinations in the acute trauma setting and lower the threshold for follow-up imaging, even in the absence of neurologic deterioration. CTA Head and Neck There is no relevant literature to support the use of CTA in the short-term follow-up imaging evaluation of acute head trauma without suspected vascular injury (see Variants 8 and 9 when suspected). Please refer to discussion under Variants 8 and 9 on imaging risk factors that are associated with intracranial vascular injury and would support the use of CTA/CTV. FDG-PET/CT Brain There is no relevant literature to support the use of FDG-PET/CT in the short-term follow-up imaging evaluation of acute head trauma. HMPAO SPECT or SPECT/CT Brain There is no relevant literature to support the use of SPECT in the short-term follow-up imaging evaluation of acute head trauma. MR Spectroscopy Head There is no relevant literature to support the use of MRS in the short-term follow-up imaging evaluation of acute head trauma. MRA Head and Neck There is no relevant literature to support the use of MRA in the short-term follow-up imaging evaluation of acute head trauma. MRI Functional (fMRI) Head There is no relevant literature to support the use of fMRI in the short-term follow-up imaging evaluation of acute head trauma. MRI Head Although brain MRI is not the most useful initial imaging modality for the evaluation of acute head trauma, it may be indicated as a follow-up study when there are persistent neurologic deficits that remain unexplained after the head CT [2].
|
Head Trauma PCAs. Based on outcomes analysis, the authors conclude that patients with mild TBI with a small convexity contusion or extra-axial hemorrhage <10 mL do not require routine repeat CT or admission to the intensive care unit in the absence of neurologic deterioration [42]. In the presence of an abnormal initial CT, other patient factors such as intoxication or pharmacologic sedation often affect the reliability of serial examinations in the acute trauma setting and lower the threshold for follow-up imaging, even in the absence of neurologic deterioration. CTA Head and Neck There is no relevant literature to support the use of CTA in the short-term follow-up imaging evaluation of acute head trauma without suspected vascular injury (see Variants 8 and 9 when suspected). Please refer to discussion under Variants 8 and 9 on imaging risk factors that are associated with intracranial vascular injury and would support the use of CTA/CTV. FDG-PET/CT Brain There is no relevant literature to support the use of FDG-PET/CT in the short-term follow-up imaging evaluation of acute head trauma. HMPAO SPECT or SPECT/CT Brain There is no relevant literature to support the use of SPECT in the short-term follow-up imaging evaluation of acute head trauma. MR Spectroscopy Head There is no relevant literature to support the use of MRS in the short-term follow-up imaging evaluation of acute head trauma. MRA Head and Neck There is no relevant literature to support the use of MRA in the short-term follow-up imaging evaluation of acute head trauma. MRI Functional (fMRI) Head There is no relevant literature to support the use of fMRI in the short-term follow-up imaging evaluation of acute head trauma. MRI Head Although brain MRI is not the most useful initial imaging modality for the evaluation of acute head trauma, it may be indicated as a follow-up study when there are persistent neurologic deficits that remain unexplained after the head CT [2].
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69481
|
acrac_69481_10
|
Head Trauma PCAs
|
MRI is more sensitive than CT for subtle findings adjacent to the calvarium or skull base (eg, small cortical contusions and subdural hematomas) [29]. It is also more sensitive for small white matter lesions in traumatic axonal injury or DAI. Only 10% of DAI is positive on CT because >80% of lesions are not associated with macroscopic hemorrhage and therefore have a higher chance of detection on MRI using a combination of T2- weighted, T2*-weighted, and diffusion-weighted images [18]. There is some controversy about the necessity of MRI in the acute phase. A single-center 2-year retrospective study of all patients with TBI who underwent both CT and MRI in the acute phase found MRI to be more sensitive for small intracranial lesions, especially shearing injuries (DAI), which could be of prognostic value in patients with unexplained poor GCS scores. However, none of these additional findings affected management plans in the acute phase [36]. A single-center 3-year prospective study of all patients with TBI who underwent both CT and MRI in the acute phase also found MRI to be more sensitive for subtle contusions, shearing injuries, and extra-axial hematomas (33% of cases). Once again, the additional information did not affect management in the acute phase [37]. Head Trauma MRI Head with DTI There is no relevant literature to support the use of DTI in the short-term follow-up imaging evaluation of acute head trauma. Radiography Skull There is no relevant literature to support the use of radiographs in the short-term follow-up imaging evaluation of acute head trauma. Arteriography Cervicocerebral There is no relevant literature to support the use of catheter angiography in the short-term follow-up imaging evaluation of acute head trauma. CT Head Head CT is useful for the evaluation of any trauma patient with neurologic deterioration, especially in the acute setting and regardless of whether the initial imaging was positive or negative [2].
|
Head Trauma PCAs. MRI is more sensitive than CT for subtle findings adjacent to the calvarium or skull base (eg, small cortical contusions and subdural hematomas) [29]. It is also more sensitive for small white matter lesions in traumatic axonal injury or DAI. Only 10% of DAI is positive on CT because >80% of lesions are not associated with macroscopic hemorrhage and therefore have a higher chance of detection on MRI using a combination of T2- weighted, T2*-weighted, and diffusion-weighted images [18]. There is some controversy about the necessity of MRI in the acute phase. A single-center 2-year retrospective study of all patients with TBI who underwent both CT and MRI in the acute phase found MRI to be more sensitive for small intracranial lesions, especially shearing injuries (DAI), which could be of prognostic value in patients with unexplained poor GCS scores. However, none of these additional findings affected management plans in the acute phase [36]. A single-center 3-year prospective study of all patients with TBI who underwent both CT and MRI in the acute phase also found MRI to be more sensitive for subtle contusions, shearing injuries, and extra-axial hematomas (33% of cases). Once again, the additional information did not affect management in the acute phase [37]. Head Trauma MRI Head with DTI There is no relevant literature to support the use of DTI in the short-term follow-up imaging evaluation of acute head trauma. Radiography Skull There is no relevant literature to support the use of radiographs in the short-term follow-up imaging evaluation of acute head trauma. Arteriography Cervicocerebral There is no relevant literature to support the use of catheter angiography in the short-term follow-up imaging evaluation of acute head trauma. CT Head Head CT is useful for the evaluation of any trauma patient with neurologic deterioration, especially in the acute setting and regardless of whether the initial imaging was positive or negative [2].
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69481
|
acrac_69481_11
|
Head Trauma PCAs
|
CT is highly sensitive for the detection of findings that may require neurosurgical intervention (eg, new or worsening hemorrhage, herniation, and hydrocephalus). Multiplanar reformatted images have been shown to increase diagnostic accuracy and should be included [16,17]. In patients with a positive initial CT, reported predictors of imaging progression include subfrontal/temporal parenchymal contusion, volume of ICH >10 mL, use of anticoagulation, and >65 years of age [42]. In patients with a negative initial CT, delayed ICH is a rare but possible complication (overall incidence <0.5%) [35]. CTA Head and Neck There is no relevant literature to support the use of CTA in the short-term follow-up imaging evaluation of acute head trauma without suspected vascular injury (see Variants 8 and 9 when suspected). FDG-PET/CT Brain There is no relevant literature to support the use of FDG-PET/CT in the short-term follow-up imaging evaluation of acute head trauma. HMPAO SPECT or SPECT/CT Brain There is no relevant literature to support the use of SPECT in the short-term follow-up imaging evaluation of acute head trauma. MR Spectroscopy Head There is no relevant literature to support the use of MRS in the short-term follow-up imaging evaluation of acute head trauma. MRA Head and Neck There is no relevant literature to support the use of MRA in the short-term follow-up imaging evaluation of acute head trauma. MRI Functional (fMRI) Head There is no relevant literature to support the use of fMRI in the short-term follow-up imaging evaluation of acute head trauma. MRI Head Head CT is the most useful follow-up imaging modality for the evaluation of any trauma patient with neurologic deterioration, especially in the acute setting, and regardless of whether the initial imaging was positive or negative [2]. Brain MRI may be indicated as a second-line study when there are persistent neurologic deficits that remain unexplained after the head CT.
|
Head Trauma PCAs. CT is highly sensitive for the detection of findings that may require neurosurgical intervention (eg, new or worsening hemorrhage, herniation, and hydrocephalus). Multiplanar reformatted images have been shown to increase diagnostic accuracy and should be included [16,17]. In patients with a positive initial CT, reported predictors of imaging progression include subfrontal/temporal parenchymal contusion, volume of ICH >10 mL, use of anticoagulation, and >65 years of age [42]. In patients with a negative initial CT, delayed ICH is a rare but possible complication (overall incidence <0.5%) [35]. CTA Head and Neck There is no relevant literature to support the use of CTA in the short-term follow-up imaging evaluation of acute head trauma without suspected vascular injury (see Variants 8 and 9 when suspected). FDG-PET/CT Brain There is no relevant literature to support the use of FDG-PET/CT in the short-term follow-up imaging evaluation of acute head trauma. HMPAO SPECT or SPECT/CT Brain There is no relevant literature to support the use of SPECT in the short-term follow-up imaging evaluation of acute head trauma. MR Spectroscopy Head There is no relevant literature to support the use of MRS in the short-term follow-up imaging evaluation of acute head trauma. MRA Head and Neck There is no relevant literature to support the use of MRA in the short-term follow-up imaging evaluation of acute head trauma. MRI Functional (fMRI) Head There is no relevant literature to support the use of fMRI in the short-term follow-up imaging evaluation of acute head trauma. MRI Head Head CT is the most useful follow-up imaging modality for the evaluation of any trauma patient with neurologic deterioration, especially in the acute setting, and regardless of whether the initial imaging was positive or negative [2]. Brain MRI may be indicated as a second-line study when there are persistent neurologic deficits that remain unexplained after the head CT.
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69481
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acrac_69481_12
|
Head Trauma PCAs
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MRI is more sensitive than CT for subtle findings adjacent to the calvarium or skull base (eg, small cortical contusions and subdural hematomas) [29]. MRI is also more sensitive for small white matter Head Trauma lesions in traumatic axonal injury or DAI. MRI with diffusion-weighted imaging can detect acute ischemic stroke (specifically infarct core) with higher sensitivity than head CT. There is some controversy about the necessity of MRI in the acute phase. A single-center 2-year retrospective study of all patients with TBI who underwent both CT and MRI in the acute phase found MRI to be more sensitive for small intracranial lesions, especially shearing injuries (DAI), which could be of prognostic value in patients with unexplained poor GCS scores. However, none of these additional findings affected management plans in the acute phase [36]. A single-center 3-year prospective study of all patients with TBI who underwent both CT and MRI in the acute phase also found MRI to be more sensitive for subtle contusions, shearing injuries, and extra-axial hematomas (33% of cases). Once again, the additional information did not affect management in the acute phase [37]. MRI Head with DTI There is no relevant literature to support the use of DTI in the short-term follow-up imaging evaluation of acute head trauma. Radiography Skull There is no relevant literature to support the use of radiographs in the short-term follow-up imaging evaluation of acute head trauma. Variant 7: Subacute or chronic head trauma with unexplained cognitive or neurologic deficit(s). Initial imaging. As noted in the introduction/background section, head trauma is a significant public health concern and is also a leading cause of morbidity and mortality in children and young adults, especially in the setting of moderate, severe, or penetrating head trauma.
|
Head Trauma PCAs. MRI is more sensitive than CT for subtle findings adjacent to the calvarium or skull base (eg, small cortical contusions and subdural hematomas) [29]. MRI is also more sensitive for small white matter Head Trauma lesions in traumatic axonal injury or DAI. MRI with diffusion-weighted imaging can detect acute ischemic stroke (specifically infarct core) with higher sensitivity than head CT. There is some controversy about the necessity of MRI in the acute phase. A single-center 2-year retrospective study of all patients with TBI who underwent both CT and MRI in the acute phase found MRI to be more sensitive for small intracranial lesions, especially shearing injuries (DAI), which could be of prognostic value in patients with unexplained poor GCS scores. However, none of these additional findings affected management plans in the acute phase [36]. A single-center 3-year prospective study of all patients with TBI who underwent both CT and MRI in the acute phase also found MRI to be more sensitive for subtle contusions, shearing injuries, and extra-axial hematomas (33% of cases). Once again, the additional information did not affect management in the acute phase [37]. MRI Head with DTI There is no relevant literature to support the use of DTI in the short-term follow-up imaging evaluation of acute head trauma. Radiography Skull There is no relevant literature to support the use of radiographs in the short-term follow-up imaging evaluation of acute head trauma. Variant 7: Subacute or chronic head trauma with unexplained cognitive or neurologic deficit(s). Initial imaging. As noted in the introduction/background section, head trauma is a significant public health concern and is also a leading cause of morbidity and mortality in children and young adults, especially in the setting of moderate, severe, or penetrating head trauma.
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69481
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acrac_69481_13
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Head Trauma PCAs
|
Even mild head trauma, which accounts for >75% of cases, can be associated with a significant risk of persistent neurocognitive/postconcussive symptoms, affecting approximately 58% at 1 month and 15% at 1 year after injury (postconcussive syndrome is defined as >3 months) [20]. There has been increasing recognition of the chronic sequelae from repetitive concussions (mild TBI) in athletic and military personnel, which can lead to neurodegenerative disease in some cases (chronic traumatic encephalopathy) [2]. A survey of 2,525 infantry soldiers returning from Operations Iraqi Freedom and Enduring Freedom found that 15% reported experiencing events associated with mild TBI, which has been termed a signature injury of those conflicts (80% secondary to improvised explosive devices) [18]. Arteriography Cervicocerebral There is no relevant literature to support the use of catheter angiography in the initial imaging evaluation of subacute or chronic head trauma with unexplained cognitive or neurologic deficit(s). CT Head Although head CT is the most useful initial imaging for the evaluation of acute head trauma, brain MRI is typically recommended as the most useful initial imaging for the evaluation of subacute or chronic head trauma, when rapid detection of acute ICH and neurosurgical lesions is no longer the primary clinical focus. MRI is more sensitive than CT for subtle findings adjacent to the calvarium or skull base (eg, focal encephalomalacia at the inferior frontal or anterior temporal lobes as chronic sequelae of previous contusions). It is also more sensitive for small white matter lesions (microbleeds) as chronic sequelae of previous traumatic axonal injury or DAI, which may help to explain persistent cognitive or neurologic deficit(s) [32]. CT is a valid option when there is a specific question that does not require the high soft-tissue contrast resolution of MRI (eg, possible shunt failure in chronic severe TBI).
|
Head Trauma PCAs. Even mild head trauma, which accounts for >75% of cases, can be associated with a significant risk of persistent neurocognitive/postconcussive symptoms, affecting approximately 58% at 1 month and 15% at 1 year after injury (postconcussive syndrome is defined as >3 months) [20]. There has been increasing recognition of the chronic sequelae from repetitive concussions (mild TBI) in athletic and military personnel, which can lead to neurodegenerative disease in some cases (chronic traumatic encephalopathy) [2]. A survey of 2,525 infantry soldiers returning from Operations Iraqi Freedom and Enduring Freedom found that 15% reported experiencing events associated with mild TBI, which has been termed a signature injury of those conflicts (80% secondary to improvised explosive devices) [18]. Arteriography Cervicocerebral There is no relevant literature to support the use of catheter angiography in the initial imaging evaluation of subacute or chronic head trauma with unexplained cognitive or neurologic deficit(s). CT Head Although head CT is the most useful initial imaging for the evaluation of acute head trauma, brain MRI is typically recommended as the most useful initial imaging for the evaluation of subacute or chronic head trauma, when rapid detection of acute ICH and neurosurgical lesions is no longer the primary clinical focus. MRI is more sensitive than CT for subtle findings adjacent to the calvarium or skull base (eg, focal encephalomalacia at the inferior frontal or anterior temporal lobes as chronic sequelae of previous contusions). It is also more sensitive for small white matter lesions (microbleeds) as chronic sequelae of previous traumatic axonal injury or DAI, which may help to explain persistent cognitive or neurologic deficit(s) [32]. CT is a valid option when there is a specific question that does not require the high soft-tissue contrast resolution of MRI (eg, possible shunt failure in chronic severe TBI).
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69481
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acrac_69481_14
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Head Trauma PCAs
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It is also a valid option for patients who present in a delayed fashion after head trauma (eg, gradual decline after a fall due to subacute or chronic subdural hematoma). Head Trauma CTA Head and Neck There is no relevant literature to support the use of CTA in the initial imaging evaluation of subacute or chronic head trauma with unexplained cognitive or neurologic deficit(s) unless there is also suspected intracranial vascular injury (see Variants 8 and 9 when suspected). FDG-PET/CT Brain FDG is the most widely used PET radiopharmaceutical and is a glucose analog. Glucose is the primary energy source for the brain; therefore, FDG uptake on PET is a marker of local metabolism, which is closely coupled to local neuronal activity and can be quantified as the cerebral metabolic rate of glucose [18]. In normally functioning brain tissue, local metabolism is also closely coupled to perfusion; therefore, findings on metabolic PET imaging will often (but not always) parallel findings on perfusion SPECT imaging [32]. In acute severe TBI with brain contusion, FDG-PET has found both pericontusion and distant/global hypometabolism, whereas in chronic mild TBI, FDG-PET has found regional hypometabolism that may correlate with cognitive and behavioral impairments [18]. One study in combat veterans with chronic postconcussive syndrome found hypometabolism in the infratentorial and medial temporal regions, which may be unique to blast exposures [44]. Aside from FDG, other research studies have used oxygen (15O), neuronal ([11C] flumazenil), inflammation ([11C] PK11195), amyloid ([11C] PiB), and tau ([18F] T807) radiopharmaceuticals [18]. Despite the promise of molecular imaging for advancing our understanding of TBI pathophysiology, there is insufficient evidence to support the routine clinical use of PET at the individual patient level [45].
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Head Trauma PCAs. It is also a valid option for patients who present in a delayed fashion after head trauma (eg, gradual decline after a fall due to subacute or chronic subdural hematoma). Head Trauma CTA Head and Neck There is no relevant literature to support the use of CTA in the initial imaging evaluation of subacute or chronic head trauma with unexplained cognitive or neurologic deficit(s) unless there is also suspected intracranial vascular injury (see Variants 8 and 9 when suspected). FDG-PET/CT Brain FDG is the most widely used PET radiopharmaceutical and is a glucose analog. Glucose is the primary energy source for the brain; therefore, FDG uptake on PET is a marker of local metabolism, which is closely coupled to local neuronal activity and can be quantified as the cerebral metabolic rate of glucose [18]. In normally functioning brain tissue, local metabolism is also closely coupled to perfusion; therefore, findings on metabolic PET imaging will often (but not always) parallel findings on perfusion SPECT imaging [32]. In acute severe TBI with brain contusion, FDG-PET has found both pericontusion and distant/global hypometabolism, whereas in chronic mild TBI, FDG-PET has found regional hypometabolism that may correlate with cognitive and behavioral impairments [18]. One study in combat veterans with chronic postconcussive syndrome found hypometabolism in the infratentorial and medial temporal regions, which may be unique to blast exposures [44]. Aside from FDG, other research studies have used oxygen (15O), neuronal ([11C] flumazenil), inflammation ([11C] PK11195), amyloid ([11C] PiB), and tau ([18F] T807) radiopharmaceuticals [18]. Despite the promise of molecular imaging for advancing our understanding of TBI pathophysiology, there is insufficient evidence to support the routine clinical use of PET at the individual patient level [45].
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69481
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acrac_69481_15
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Head Trauma PCAs
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HMPAO SPECT or SPECT/CT Brain Although SPECT is used clinically with a wide variety of radiopharmaceuticals, brain SPECT most commonly refers to cerebral perfusion or blood flow imaging using either Tc-99m-hexamethylpropyleneamine oxime or Tc- 99m-ethyl cysteinate dimer. Measurement of regional cerebral blood flow is also an indicator of metabolic or neuronal activity; therefore, SPECT is utilized in epilepsy or neurodegenerative disorders in addition to cerebrovascular diseases. Other radiopharmaceuticals (eg, imaging of benzodiazepine or dopamine receptors) are generally confined to research studies. Perfusion SPECT is potentially a complementary tool to conventional CT/MRI and has been applied in research studies on mild, moderate, and severe TBI to identify additional lesions (eg, regional cerebral blood flow deficits) beyond anatomic imaging [18]. A study using early subacute SPECT in patients with mild to moderate TBI found that severe hypoperfusion was an independent predictor of unfavorable outcomes at 3 months; conversely, a normal initial SPECT has been shown to have high negative predictive value for persistent clinical deficits at 12 months [46]. Despite the promise of perfusion imaging (whether employing SPECT or CT/MRI-based techniques) for the detection of functional injury that may be occult on structural imaging, there is insufficient evidence to support the routine clinical use of SPECT at the individual patient level [45]. MR Spectroscopy Head MRS measures very small differences in the precessional frequencies of proton nuclei in order to differentiate their molecular environments (chemical shift effect). Single-voxel versus multi-voxel spectroscopy offers different strengths and weaknesses in signal-to-noise ratio versus spatial coverage; both have lower spatial resolution than other MRI-based techniques.
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Head Trauma PCAs. HMPAO SPECT or SPECT/CT Brain Although SPECT is used clinically with a wide variety of radiopharmaceuticals, brain SPECT most commonly refers to cerebral perfusion or blood flow imaging using either Tc-99m-hexamethylpropyleneamine oxime or Tc- 99m-ethyl cysteinate dimer. Measurement of regional cerebral blood flow is also an indicator of metabolic or neuronal activity; therefore, SPECT is utilized in epilepsy or neurodegenerative disorders in addition to cerebrovascular diseases. Other radiopharmaceuticals (eg, imaging of benzodiazepine or dopamine receptors) are generally confined to research studies. Perfusion SPECT is potentially a complementary tool to conventional CT/MRI and has been applied in research studies on mild, moderate, and severe TBI to identify additional lesions (eg, regional cerebral blood flow deficits) beyond anatomic imaging [18]. A study using early subacute SPECT in patients with mild to moderate TBI found that severe hypoperfusion was an independent predictor of unfavorable outcomes at 3 months; conversely, a normal initial SPECT has been shown to have high negative predictive value for persistent clinical deficits at 12 months [46]. Despite the promise of perfusion imaging (whether employing SPECT or CT/MRI-based techniques) for the detection of functional injury that may be occult on structural imaging, there is insufficient evidence to support the routine clinical use of SPECT at the individual patient level [45]. MR Spectroscopy Head MRS measures very small differences in the precessional frequencies of proton nuclei in order to differentiate their molecular environments (chemical shift effect). Single-voxel versus multi-voxel spectroscopy offers different strengths and weaknesses in signal-to-noise ratio versus spatial coverage; both have lower spatial resolution than other MRI-based techniques.
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69481
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acrac_69481_16
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Head Trauma PCAs
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Commonly detected brain metabolites at intermediate (TE = 144 ms) to long (TE = 288 ms) echo time include N-acetylaspartate for neuronal integrity, creatine for cellular energy, choline for membrane turnover, and lactate for anaerobic metabolism. MRS at short (TE = 35 ms) echo time can further detect glutamate/glutamine for excitatory brain injury and myo-inositol for astroglial proliferation. The most commonly reported finding in the setting of head trauma is a reduction in N-acetylaspartate or N-acetylaspartate/creatine, sometimes accompanied by an elevation in choline and sometimes in otherwise normal-appearing brain, which may reflect microscopic DAI and/or Wallerian degeneration [32,45,46]. A study in concussed athletes found that decreased N-acetylaspartate/creatine took a longer time to resolve than the symptoms, suggesting that metabolic recovery is slower than clinical recovery [18]. Despite the interesting findings in MRS research, there is insufficient evidence to support the routine clinical use of MRS at the individual patient level [45]. MRA Head and Neck There is no relevant literature to support the use of MRA in the initial imaging evaluation of subacute or chronic head trauma with unexplained cognitive or neurologic deficit(s). Head Trauma MRI Head Brain MRI is the most useful initial imaging for the evaluation of subacute or chronic head trauma with unexplained cognitive or neurologic deficit(s). Conventional MRI will include a combination of T1-weighted, T2-weighted, T2*-weighted (gradient-echo), and diffusion-weighted imaging. It is more sensitive than CT for subtle findings adjacent to the calvarium or skull base (eg, focal encephalomalacia at the inferior frontal or anterior temporal lobes as chronic sequelae of previous contusions). It is also more sensitive for small white matter lesions (microbleeds) as chronic sequelae of previous traumatic axonal injury or DAI, although it is still far less sensitive than neuropathological investigation (microscopic analysis) [32].
|
Head Trauma PCAs. Commonly detected brain metabolites at intermediate (TE = 144 ms) to long (TE = 288 ms) echo time include N-acetylaspartate for neuronal integrity, creatine for cellular energy, choline for membrane turnover, and lactate for anaerobic metabolism. MRS at short (TE = 35 ms) echo time can further detect glutamate/glutamine for excitatory brain injury and myo-inositol for astroglial proliferation. The most commonly reported finding in the setting of head trauma is a reduction in N-acetylaspartate or N-acetylaspartate/creatine, sometimes accompanied by an elevation in choline and sometimes in otherwise normal-appearing brain, which may reflect microscopic DAI and/or Wallerian degeneration [32,45,46]. A study in concussed athletes found that decreased N-acetylaspartate/creatine took a longer time to resolve than the symptoms, suggesting that metabolic recovery is slower than clinical recovery [18]. Despite the interesting findings in MRS research, there is insufficient evidence to support the routine clinical use of MRS at the individual patient level [45]. MRA Head and Neck There is no relevant literature to support the use of MRA in the initial imaging evaluation of subacute or chronic head trauma with unexplained cognitive or neurologic deficit(s). Head Trauma MRI Head Brain MRI is the most useful initial imaging for the evaluation of subacute or chronic head trauma with unexplained cognitive or neurologic deficit(s). Conventional MRI will include a combination of T1-weighted, T2-weighted, T2*-weighted (gradient-echo), and diffusion-weighted imaging. It is more sensitive than CT for subtle findings adjacent to the calvarium or skull base (eg, focal encephalomalacia at the inferior frontal or anterior temporal lobes as chronic sequelae of previous contusions). It is also more sensitive for small white matter lesions (microbleeds) as chronic sequelae of previous traumatic axonal injury or DAI, although it is still far less sensitive than neuropathological investigation (microscopic analysis) [32].
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69481
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acrac_69481_17
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Head Trauma PCAs
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Susceptibility-weighted imaging is a high-resolution 3-D T2*-weighted sequence that uses both magnitude and phase information to increase sensitivity for paramagnetic blood products (eg, pediatric TBI studies have detected 6 times as many microbleeds with susceptibility-weighted imaging than with older gradient-echo T2*-weighted sequences) [18]. In addition to detecting subtle structural injury, conventional MRI may help with the prognostication of long-term neurocognitive sequelae. Regarding mild head trauma, a prospective Level 1 trauma multicenter study found that abnormalities on early subacute MRI (eg, small cortical contusions or hemorrhagic axonal injury) are clinically relevant in improving prediction of 3-month outcomes [38]. Another prospective study in patients with mild TBI found a correlation between frontal-temporal-parietal microbleeds on early MRI susceptibility-weighted imaging and the presence or absence of depressive symptoms at 1 year after injury [50]. Regarding moderate to severe head trauma, one study found DAI on subacute MRI in almost three-quarters of patients who survived the acute phase, and only in those patients was GCS score (which tended to be lower) related to 12-month outcomes. It also found similar outcomes for DAI Stage 1 (lobar white matter lesions only) and DAI Stage 2 (callosal lesions), with poor outcomes for DAI Stage 3 (dorsolateral brain stem lesions) [51]. Another study on subacute MRI in post-TBI vegetative states found that depth/stage of DAI lesions helps predict recovery or nonrecovery at 1 year [52]. There is no relevant literature to support the added value or routine use of contrast-enhanced brain MRI instead of noncontrast brain MRI in the initial imaging evaluation of subacute or chronic head trauma. MRI Head with DTI Diffusion-weighted imaging generates a scalar coefficient for each voxel, which represents the average or mean diffusivity (mm2/s) of the water molecules in that location.
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Head Trauma PCAs. Susceptibility-weighted imaging is a high-resolution 3-D T2*-weighted sequence that uses both magnitude and phase information to increase sensitivity for paramagnetic blood products (eg, pediatric TBI studies have detected 6 times as many microbleeds with susceptibility-weighted imaging than with older gradient-echo T2*-weighted sequences) [18]. In addition to detecting subtle structural injury, conventional MRI may help with the prognostication of long-term neurocognitive sequelae. Regarding mild head trauma, a prospective Level 1 trauma multicenter study found that abnormalities on early subacute MRI (eg, small cortical contusions or hemorrhagic axonal injury) are clinically relevant in improving prediction of 3-month outcomes [38]. Another prospective study in patients with mild TBI found a correlation between frontal-temporal-parietal microbleeds on early MRI susceptibility-weighted imaging and the presence or absence of depressive symptoms at 1 year after injury [50]. Regarding moderate to severe head trauma, one study found DAI on subacute MRI in almost three-quarters of patients who survived the acute phase, and only in those patients was GCS score (which tended to be lower) related to 12-month outcomes. It also found similar outcomes for DAI Stage 1 (lobar white matter lesions only) and DAI Stage 2 (callosal lesions), with poor outcomes for DAI Stage 3 (dorsolateral brain stem lesions) [51]. Another study on subacute MRI in post-TBI vegetative states found that depth/stage of DAI lesions helps predict recovery or nonrecovery at 1 year [52]. There is no relevant literature to support the added value or routine use of contrast-enhanced brain MRI instead of noncontrast brain MRI in the initial imaging evaluation of subacute or chronic head trauma. MRI Head with DTI Diffusion-weighted imaging generates a scalar coefficient for each voxel, which represents the average or mean diffusivity (mm2/s) of the water molecules in that location.
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69481
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acrac_69481_18
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Head Trauma PCAs
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DTI applies the diffusion-sensitizing gradients in many (at least 6) different directions in order to generate a second-order tensor that characterizes directionality of water molecule diffusion. This can be visualized as a diffusion ellipsoid, where the long axis represents axial diffusivity, and the short axes represent radial diffusivity. An important summary measure of the degree of asymmetry between the long and short axes is fractional anisotropy. Fractional anisotropy is higher in white matter than gray matter or CSF because of its microstructure (fiber-tract architecture); therefore, fractional anisotropy has been studied extensively as a potential marker of axonal integrity, especially in the setting of persistently symptomatic mild TBI [18]. Multiple studies have shown regions of decreased fractional anisotropy and increased mean diffusivity in patients with mild, moderate, and severe TBI, as compared with healthy controls [53]. Other DTI studies performed in the early subacute phase have shown paradoxically increased fractional anisotropy, which has been attributed to cytotoxic edema or to postinjury repair [54,55]. Overall, there is significant heterogeneity in fractional anisotropy measurements among both TBI and healthy subjects, with published data based primarily upon group-level analyses. Despite continuing improvements in scanner gradients and diffusion techniques (eg, intravoxel resolution Head Trauma of crossing fibers), there is insufficient evidence to support the routine clinical use of DTI at the individual patient level [45]. Radiography Skull There is no relevant literature to support the use of radiographs in the initial imaging evaluation of subacute or chronic head trauma with unexplained cognitive or neurologic deficit(s). Variant 8: Head trauma with suspected intracranial arterial injury due to clinical risk factors or positive findings on prior imaging.
|
Head Trauma PCAs. DTI applies the diffusion-sensitizing gradients in many (at least 6) different directions in order to generate a second-order tensor that characterizes directionality of water molecule diffusion. This can be visualized as a diffusion ellipsoid, where the long axis represents axial diffusivity, and the short axes represent radial diffusivity. An important summary measure of the degree of asymmetry between the long and short axes is fractional anisotropy. Fractional anisotropy is higher in white matter than gray matter or CSF because of its microstructure (fiber-tract architecture); therefore, fractional anisotropy has been studied extensively as a potential marker of axonal integrity, especially in the setting of persistently symptomatic mild TBI [18]. Multiple studies have shown regions of decreased fractional anisotropy and increased mean diffusivity in patients with mild, moderate, and severe TBI, as compared with healthy controls [53]. Other DTI studies performed in the early subacute phase have shown paradoxically increased fractional anisotropy, which has been attributed to cytotoxic edema or to postinjury repair [54,55]. Overall, there is significant heterogeneity in fractional anisotropy measurements among both TBI and healthy subjects, with published data based primarily upon group-level analyses. Despite continuing improvements in scanner gradients and diffusion techniques (eg, intravoxel resolution Head Trauma of crossing fibers), there is insufficient evidence to support the routine clinical use of DTI at the individual patient level [45]. Radiography Skull There is no relevant literature to support the use of radiographs in the initial imaging evaluation of subacute or chronic head trauma with unexplained cognitive or neurologic deficit(s). Variant 8: Head trauma with suspected intracranial arterial injury due to clinical risk factors or positive findings on prior imaging.
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69481
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acrac_69481_19
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Head Trauma PCAs
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The reported incidence of blunt cerebrovascular injury (BCVI) has increased from approximately 0.1% to 1.0% of patients with closed head/neck trauma, with increased screening of asymptomatic patients. Symptomatic patients will have developed secondary strokes, which are associated with significant morbidity of up to 80% and mortality of up to 40% [56]. There is a variable latent period between vascular injury and symptom onset, with 17% to 36% developing symptoms >24 hours after injury, and when screening appropriately based on clinical or imaging risk factors, approximately 52% to 79% of patients with detected BCVI are asymptomatic [57]. Cerebrovascular injury is also a potential concern in the less common setting of penetrating head/neck trauma. In addition to indirect evidence of arterial injury on prior imaging (eg, hemorrhage or infarct), BCVI has a known association with head/face and cervical fractures. For example, with regard to intracranial arterial injury, positive imaging findings of a skull base fracture that involves the carotid canal or abnormal enlargement of the superior ophthalmic vein and cavernous sinus should prompt evaluation for a petrous or cavernous internal carotid artery injury, respectively [58]. Above the level of the skull base, the branches of the middle and anterior cerebral arteries are often at risk in the setting of penetrating head trauma [30]. Regarding clinical risk factors for BCVI, there are various screening criteria available, which involve tradeoffs in sensitivity (ranging between 63% and 84%) and positive predictive value or screening yield (ranging between 6% and 29%), similar to the clinical decision rules for selective CT scanning in mild head trauma [57]. The 2 original clinical decision rules were the Denver criteria (from University of Colorado) and the Memphis criteria (from University of Tennessee).
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Head Trauma PCAs. The reported incidence of blunt cerebrovascular injury (BCVI) has increased from approximately 0.1% to 1.0% of patients with closed head/neck trauma, with increased screening of asymptomatic patients. Symptomatic patients will have developed secondary strokes, which are associated with significant morbidity of up to 80% and mortality of up to 40% [56]. There is a variable latent period between vascular injury and symptom onset, with 17% to 36% developing symptoms >24 hours after injury, and when screening appropriately based on clinical or imaging risk factors, approximately 52% to 79% of patients with detected BCVI are asymptomatic [57]. Cerebrovascular injury is also a potential concern in the less common setting of penetrating head/neck trauma. In addition to indirect evidence of arterial injury on prior imaging (eg, hemorrhage or infarct), BCVI has a known association with head/face and cervical fractures. For example, with regard to intracranial arterial injury, positive imaging findings of a skull base fracture that involves the carotid canal or abnormal enlargement of the superior ophthalmic vein and cavernous sinus should prompt evaluation for a petrous or cavernous internal carotid artery injury, respectively [58]. Above the level of the skull base, the branches of the middle and anterior cerebral arteries are often at risk in the setting of penetrating head trauma [30]. Regarding clinical risk factors for BCVI, there are various screening criteria available, which involve tradeoffs in sensitivity (ranging between 63% and 84%) and positive predictive value or screening yield (ranging between 6% and 29%), similar to the clinical decision rules for selective CT scanning in mild head trauma [57]. The 2 original clinical decision rules were the Denver criteria (from University of Colorado) and the Memphis criteria (from University of Tennessee).
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69481
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acrac_69481_20
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Head Trauma PCAs
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Both have since been broadened into the modified Denver criteria and the modified Memphis criteria, with the more recently introduced Boston criteria being based on the modified Denver criteria. For clinicians or providers who are not currently committed to a screening criteria for BCVI, one simple option is the 2010 guidelines from the Eastern Association for the Surgery of Trauma [56]: Arteriography Cervicocerebral Although catheter angiography is the historical reference standard and offers the highest spatial/temporal resolution for imaging evaluation of vascular pathology, noninvasive CTA is faster, has fewer safety concerns, and is most useful in the initial imaging evaluation of suspected intracranial arterial injury [45]. With modern CT equipment, accuracy has been shown to be comparable. One prospective study of 146 trauma patients who received both catheter angiography and CTA (16-slice multidetector-row) reported the latter to have a sensitivity of 97.7% and a specificity of 100% for the diagnosis of vascular injury [60]. Catheter angiography may be useful when CTA is inconclusive (eg, possible arteriovenous fistula) or when endovascular intervention is being considered [45]. Head Trauma CT Head Please refer to CTA for neurovascular imaging evaluation of suspected intracranial arterial injury. Concurrent CT may be useful in the clinical setting of suspected intracranial arterial injury for assessing structural changes to the brain since the most recent neuroimaging study (eg, new or progressive neurologic deficit). Concurrent head CT is also useful in the initial imaging evaluation of head trauma when there is no prior imaging. CTA Head and Neck Although catheter angiography is the historical reference standard and offers the highest spatial/temporal resolution for imaging evaluation of vascular pathology, noninvasive CTA is faster, has fewer safety concerns, and is most useful in the initial imaging evaluation of suspected intracranial arterial injury [45].
|
Head Trauma PCAs. Both have since been broadened into the modified Denver criteria and the modified Memphis criteria, with the more recently introduced Boston criteria being based on the modified Denver criteria. For clinicians or providers who are not currently committed to a screening criteria for BCVI, one simple option is the 2010 guidelines from the Eastern Association for the Surgery of Trauma [56]: Arteriography Cervicocerebral Although catheter angiography is the historical reference standard and offers the highest spatial/temporal resolution for imaging evaluation of vascular pathology, noninvasive CTA is faster, has fewer safety concerns, and is most useful in the initial imaging evaluation of suspected intracranial arterial injury [45]. With modern CT equipment, accuracy has been shown to be comparable. One prospective study of 146 trauma patients who received both catheter angiography and CTA (16-slice multidetector-row) reported the latter to have a sensitivity of 97.7% and a specificity of 100% for the diagnosis of vascular injury [60]. Catheter angiography may be useful when CTA is inconclusive (eg, possible arteriovenous fistula) or when endovascular intervention is being considered [45]. Head Trauma CT Head Please refer to CTA for neurovascular imaging evaluation of suspected intracranial arterial injury. Concurrent CT may be useful in the clinical setting of suspected intracranial arterial injury for assessing structural changes to the brain since the most recent neuroimaging study (eg, new or progressive neurologic deficit). Concurrent head CT is also useful in the initial imaging evaluation of head trauma when there is no prior imaging. CTA Head and Neck Although catheter angiography is the historical reference standard and offers the highest spatial/temporal resolution for imaging evaluation of vascular pathology, noninvasive CTA is faster, has fewer safety concerns, and is most useful in the initial imaging evaluation of suspected intracranial arterial injury [45].
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69481
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acrac_69481_21
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Head Trauma PCAs
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With modern CT equipment, accuracy has been shown to be comparable. One prospective study of 146 trauma patients who received both catheter angiography and CTA (16-slice multidetector-row) reported the latter to have a sensitivity of 97.7% and a specificity of 100% for the diagnosis of vascular injury [60]. The development of >8-slice multidetector-row CT has allowed CTA to become the standard in diagnosis of suspected cerebrovascular injury, with reported sensitivities up to 100% (somewhat dependent on both CT technology and radiologist expertise) [57]. There is a Biffl grading scale for arterial injury, which was originally developed for catheter angiography and carotid artery injury but has also been shown to be reliable for CTA and vertebral artery injury [56]. Grade I = dissection with <25% luminal narrowing (intimal irregularity), Grade II = dissection with >25% luminal narrowing (intramural hematoma), Grade III = pseudoaneurysm (contained hematoma), Grade IV = occlusion, and Grade V = transection or hemodynamically significant arteriovenous fistula (eg, carotid cavernous fistula). Medical therapy with antiplatelet or anticoagulation may be appropriate management for the lower grades of arterial injury, whereas the higher grades of arterial injury are more likely to require endovascular or surgical treatment [56,57]. FDG-PET/CT Brain There is no relevant literature to support the use of FDG-PET/CT in the imaging evaluation of suspected intracranial arterial injury. HMPAO SPECT or SPECT/CT Brain There is no relevant literature to support the use of SPECT in the imaging evaluation of suspected intracranial arterial injury. MR Spectroscopy Head There is no relevant literature to support the use of MRS in the imaging evaluation of suspected intracranial arterial injury.
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Head Trauma PCAs. With modern CT equipment, accuracy has been shown to be comparable. One prospective study of 146 trauma patients who received both catheter angiography and CTA (16-slice multidetector-row) reported the latter to have a sensitivity of 97.7% and a specificity of 100% for the diagnosis of vascular injury [60]. The development of >8-slice multidetector-row CT has allowed CTA to become the standard in diagnosis of suspected cerebrovascular injury, with reported sensitivities up to 100% (somewhat dependent on both CT technology and radiologist expertise) [57]. There is a Biffl grading scale for arterial injury, which was originally developed for catheter angiography and carotid artery injury but has also been shown to be reliable for CTA and vertebral artery injury [56]. Grade I = dissection with <25% luminal narrowing (intimal irregularity), Grade II = dissection with >25% luminal narrowing (intramural hematoma), Grade III = pseudoaneurysm (contained hematoma), Grade IV = occlusion, and Grade V = transection or hemodynamically significant arteriovenous fistula (eg, carotid cavernous fistula). Medical therapy with antiplatelet or anticoagulation may be appropriate management for the lower grades of arterial injury, whereas the higher grades of arterial injury are more likely to require endovascular or surgical treatment [56,57]. FDG-PET/CT Brain There is no relevant literature to support the use of FDG-PET/CT in the imaging evaluation of suspected intracranial arterial injury. HMPAO SPECT or SPECT/CT Brain There is no relevant literature to support the use of SPECT in the imaging evaluation of suspected intracranial arterial injury. MR Spectroscopy Head There is no relevant literature to support the use of MRS in the imaging evaluation of suspected intracranial arterial injury.
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acrac_69481_22
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Head Trauma PCAs
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MRA Head and Neck In the setting of acute trauma, MRA is considered a second-line noninvasive option behind CTA, which is faster, has fewer safety concerns, and is most useful in the initial imaging evaluation of suspected intracranial arterial injury [45]. MRA may be useful outside of the acute setting or when CTA is inconclusive (eg, for detection of T1 hyperintense subacute intramural hematoma in traumatic arterial dissection) [57]. Noncontrast MRA, using time- of-flight technique, can be used in patients who cannot receive iodinated or gadolinium-based contrast. MRI Functional (fMRI) Head There is no relevant literature to support the use of fMRI in the imaging evaluation of suspected intracranial arterial injury. MRI Head Please refer to MRA for neurovascular imaging evaluation of suspected intracranial arterial injury. Concurrent MRI may be useful in the clinical setting of suspected intracranial arterial injury for assessing structural changes to the brain since the most recent neuroimaging study (eg, new or progressive neurologic deficit). MRI Head with DTI There is no relevant literature to support the use of DTI in the imaging evaluation of suspected intracranial arterial injury. Radiography Skull There is no relevant literature to support the use of radiographs in the imaging evaluation of suspected intracranial arterial injury. Head Trauma Variant 9: Head trauma with suspected intracranial venous injury due to clinical risk factors or positive findings on prior imaging. Traumatic venous injury is an often-overlooked pathology that includes epithelial injury with thrombus formation and venous laceration with compressive hematoma [57]. The most common symptoms are highly variable and nonspecific (eg, headache and papilledema from intracranial hypertension or focal neurologic deficits from venous ischemia); they may be mistakenly attributed to other traumatic injuries [61].
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Head Trauma PCAs. MRA Head and Neck In the setting of acute trauma, MRA is considered a second-line noninvasive option behind CTA, which is faster, has fewer safety concerns, and is most useful in the initial imaging evaluation of suspected intracranial arterial injury [45]. MRA may be useful outside of the acute setting or when CTA is inconclusive (eg, for detection of T1 hyperintense subacute intramural hematoma in traumatic arterial dissection) [57]. Noncontrast MRA, using time- of-flight technique, can be used in patients who cannot receive iodinated or gadolinium-based contrast. MRI Functional (fMRI) Head There is no relevant literature to support the use of fMRI in the imaging evaluation of suspected intracranial arterial injury. MRI Head Please refer to MRA for neurovascular imaging evaluation of suspected intracranial arterial injury. Concurrent MRI may be useful in the clinical setting of suspected intracranial arterial injury for assessing structural changes to the brain since the most recent neuroimaging study (eg, new or progressive neurologic deficit). MRI Head with DTI There is no relevant literature to support the use of DTI in the imaging evaluation of suspected intracranial arterial injury. Radiography Skull There is no relevant literature to support the use of radiographs in the imaging evaluation of suspected intracranial arterial injury. Head Trauma Variant 9: Head trauma with suspected intracranial venous injury due to clinical risk factors or positive findings on prior imaging. Traumatic venous injury is an often-overlooked pathology that includes epithelial injury with thrombus formation and venous laceration with compressive hematoma [57]. The most common symptoms are highly variable and nonspecific (eg, headache and papilledema from intracranial hypertension or focal neurologic deficits from venous ischemia); they may be mistakenly attributed to other traumatic injuries [61].
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69481
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acrac_69481_23
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Head Trauma PCAs
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From an imaging standpoint, the most important risk factor for traumatic venous injury is a skull fracture (or less commonly a penetrating foreign body) that involves a dural venous sinus or jugular bulb/foramen. In a retrospective study of 195 patients with closed head trauma who received multidetector-row CTV, acute traumatic venous sinus thrombosis was seen only in those patients with fractures extending to a dural sinus or jugular bulb (41% rate of thrombosis), and hemorrhagic venous infarctions were seen only in the setting of occlusive dural venous sinus thrombosis (55% of all thromboses) [62]. Another retrospective study of 472 patients with closed head trauma with skull fracture crossing a dural venous sinus also identified a high incidence of small epidural hemorrhages (81%), which can be compressive and misdiagnosed as venous sinus thrombosis [61]. Direct observation of hyperattenuating thrombus within a dural venous sinus on a noncontrast CT should prompt further evaluation; however, this is present in only one-third of venous sinus thrombosis. Indirect evidence of dural sinus thrombosis includes venous infarcts (subcortical edema), one-third of which develop parenchymal hemorrhage [30]. Arteriography Cervicocerebral There is no relevant literature to support the use of catheter angiography in the imaging evaluation of suspected intracranial venous injury. CT Head Please refer to CTV for neurovascular imaging evaluation of suspected intracranial venous injury. Concurrent CT may be useful in the clinical setting of suspected intracranial venous injury for assessing structural changes to the brain since the most recent neuroimaging study (eg, new or progressive neurologic deficit). Concurrent head CT is also useful in the initial imaging evaluation of head trauma when there is no prior imaging. FDG-PET/CT Brain There is no relevant literature to support the use of FDG-PET/CT in the imaging evaluation of suspected intracranial venous injury.
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Head Trauma PCAs. From an imaging standpoint, the most important risk factor for traumatic venous injury is a skull fracture (or less commonly a penetrating foreign body) that involves a dural venous sinus or jugular bulb/foramen. In a retrospective study of 195 patients with closed head trauma who received multidetector-row CTV, acute traumatic venous sinus thrombosis was seen only in those patients with fractures extending to a dural sinus or jugular bulb (41% rate of thrombosis), and hemorrhagic venous infarctions were seen only in the setting of occlusive dural venous sinus thrombosis (55% of all thromboses) [62]. Another retrospective study of 472 patients with closed head trauma with skull fracture crossing a dural venous sinus also identified a high incidence of small epidural hemorrhages (81%), which can be compressive and misdiagnosed as venous sinus thrombosis [61]. Direct observation of hyperattenuating thrombus within a dural venous sinus on a noncontrast CT should prompt further evaluation; however, this is present in only one-third of venous sinus thrombosis. Indirect evidence of dural sinus thrombosis includes venous infarcts (subcortical edema), one-third of which develop parenchymal hemorrhage [30]. Arteriography Cervicocerebral There is no relevant literature to support the use of catheter angiography in the imaging evaluation of suspected intracranial venous injury. CT Head Please refer to CTV for neurovascular imaging evaluation of suspected intracranial venous injury. Concurrent CT may be useful in the clinical setting of suspected intracranial venous injury for assessing structural changes to the brain since the most recent neuroimaging study (eg, new or progressive neurologic deficit). Concurrent head CT is also useful in the initial imaging evaluation of head trauma when there is no prior imaging. FDG-PET/CT Brain There is no relevant literature to support the use of FDG-PET/CT in the imaging evaluation of suspected intracranial venous injury.
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69481
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acrac_69481_24
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Head Trauma PCAs
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HMPAO SPECT or SPECT/CT Brain There is no relevant literature to support the use of SPECT in the imaging evaluation of suspected intracranial venous injury. MR Spectroscopy Head There is no relevant literature to support the use of MRS in the imaging evaluation of suspected intracranial venous injury. MRI Functional (fMRI) Head There is no relevant literature to support the use of fMRI in the imaging evaluation of suspected intracranial venous injury. MRI Head Please refer to MRV for neurovascular imaging evaluation of suspected intracranial venous injury. Concurrent MRI may be useful in the clinical setting of suspected intracranial venous injury for assessing structural changes to the brain since the most recent neuroimaging study (eg, new or progressive neurologic deficit). Head Trauma MRI Head with DTI There is no relevant literature to support the use of DTI in the imaging evaluation of suspected intracranial venous injury. MRV Head In the setting of acute trauma, MRV is considered a second-line noninvasive option behind CTV, which is faster, has fewer safety concerns, and is most useful in the initial imaging evaluation of suspected intracranial venous injury [58]. MRV may be useful outside of the acute setting, and noncontrast MRV using time-of-flight or phase- contrast techniques can be used in patients who cannot receive iodinated or gadolinium-based contrast. Radiography Skull There is no relevant literature to support the use of radiographs in the imaging evaluation of suspected intracranial venous injury. CT Head Cisternography CT cisternography is high-resolution CT (HRCT) of the skull base after a lumbar puncture for intrathecal administration of approximately 10 mL of an iodinated contrast agent (eg, 3 g of iodine).
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Head Trauma PCAs. HMPAO SPECT or SPECT/CT Brain There is no relevant literature to support the use of SPECT in the imaging evaluation of suspected intracranial venous injury. MR Spectroscopy Head There is no relevant literature to support the use of MRS in the imaging evaluation of suspected intracranial venous injury. MRI Functional (fMRI) Head There is no relevant literature to support the use of fMRI in the imaging evaluation of suspected intracranial venous injury. MRI Head Please refer to MRV for neurovascular imaging evaluation of suspected intracranial venous injury. Concurrent MRI may be useful in the clinical setting of suspected intracranial venous injury for assessing structural changes to the brain since the most recent neuroimaging study (eg, new or progressive neurologic deficit). Head Trauma MRI Head with DTI There is no relevant literature to support the use of DTI in the imaging evaluation of suspected intracranial venous injury. MRV Head In the setting of acute trauma, MRV is considered a second-line noninvasive option behind CTV, which is faster, has fewer safety concerns, and is most useful in the initial imaging evaluation of suspected intracranial venous injury [58]. MRV may be useful outside of the acute setting, and noncontrast MRV using time-of-flight or phase- contrast techniques can be used in patients who cannot receive iodinated or gadolinium-based contrast. Radiography Skull There is no relevant literature to support the use of radiographs in the imaging evaluation of suspected intracranial venous injury. CT Head Cisternography CT cisternography is high-resolution CT (HRCT) of the skull base after a lumbar puncture for intrathecal administration of approximately 10 mL of an iodinated contrast agent (eg, 3 g of iodine).
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69481
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