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acrac_3102389_4

Congenital or Acquired Heart Disease

TEE is also useful in certain patients to guide interventional procedures or evaluate valve anatomy when transthoracic imaging is challenging, or when infectious endocarditis is suspected [12]. Variant 2: Child or adult. Transposition of the great arteries after atrial switch. Incomplete or inadequate assessment of cardiovascular morphology and function after transthoracic echocardiography. Next imaging study. Transposition of the great arteries (TGA) is a cardiac congenital defect characterized by discordant ventriculoarterial connections, in which the aorta arises above the morphological RV, and the pulmonary artery arises above the morphological LV. In TGA, the aorta usually is anterior to the PA, but it can be beside or behind the PA. The prevalence of TGA is 4.7 per 10,000 live births [19]. TGA accounts for 3% of all CHD and 20% of cyanotic heart disease. There are 2 major types of surgery performed for D-TGA: the atrial switch procedures (Mustard and Senning procedures) and the arterial switch procedures (Jatene procedure). In the atrial switch procedure, intra- atrial venous baffles redirect the systemic and pulmonary venous blood returns to the appropriate atria restoring circulating blood flow. These baffles are created by either using in situ tissue from the right atrial wall and interatrial septum (Senning procedure) or with autologous or synthetic material (Mustard procedure). Ventriculoseptal defects, if present, are also closed. Patients with Mustard or Senning type repair are now typically adult patients. The most common complications following the atrial switch procedures are intra-atrial venous baffle stenoses and leaks. Baffle stenoses typically occur at the superior limb of the baffle where the superior vena cava meets the right atrium. Baffle obstructions and leaks are estimated to occur in approximately 25% of patients [20]. The most important and relatively common postoperative complication is hypertrophy and decreased function of the systemic RV.

Congenital or Acquired Heart Disease. TEE is also useful in certain patients to guide interventional procedures or evaluate valve anatomy when transthoracic imaging is challenging, or when infectious endocarditis is suspected [12]. Variant 2: Child or adult. Transposition of the great arteries after atrial switch. Incomplete or inadequate assessment of cardiovascular morphology and function after transthoracic echocardiography. Next imaging study. Transposition of the great arteries (TGA) is a cardiac congenital defect characterized by discordant ventriculoarterial connections, in which the aorta arises above the morphological RV, and the pulmonary artery arises above the morphological LV. In TGA, the aorta usually is anterior to the PA, but it can be beside or behind the PA. The prevalence of TGA is 4.7 per 10,000 live births [19]. TGA accounts for 3% of all CHD and 20% of cyanotic heart disease. There are 2 major types of surgery performed for D-TGA: the atrial switch procedures (Mustard and Senning procedures) and the arterial switch procedures (Jatene procedure). In the atrial switch procedure, intra- atrial venous baffles redirect the systemic and pulmonary venous blood returns to the appropriate atria restoring circulating blood flow. These baffles are created by either using in situ tissue from the right atrial wall and interatrial septum (Senning procedure) or with autologous or synthetic material (Mustard procedure). Ventriculoseptal defects, if present, are also closed. Patients with Mustard or Senning type repair are now typically adult patients. The most common complications following the atrial switch procedures are intra-atrial venous baffle stenoses and leaks. Baffle stenoses typically occur at the superior limb of the baffle where the superior vena cava meets the right atrium. Baffle obstructions and leaks are estimated to occur in approximately 25% of patients [20]. The most important and relatively common postoperative complication is hypertrophy and decreased function of the systemic RV.

3102389

acrac_3102389_5

Congenital or Acquired Heart Disease

Less common complications include pulmonary arterial hypertension, residual VSD, subpulmonary stenosis, and arrhythmias. Arteriography Coronary with Ventriculography Since the coronary arteries are not surgically manipulated during an atrial switch procedure, there is no defined role for coronary arteriography in this setting. In patients with complex coronary anatomy in the setting of TGA, angiography may be helpful to demonstrate dynamic compression and angulation of the coronary arteries in patients with an interarterial course or in those with a muscular bridge [21], but this role has been superseded by CTA in most centers. Arteriography Pulmonary Pulmonary arteriography may be helpful if hemodynamic assessment of pulmonary artery pressure and resistance is required. Pulmonary arteriography is performed during interventions such as branch pulmonary artery balloon dilation and stent placement, to assess for baffle leaks, or narrowing of the systemic or pulmonary venous pathways [21]. CT Heart Function and Morphology CT is an alternative imaging modality to provide incremental information to echocardiography. CT functional assessment is a safer option to CMR in patients who are hemodynamically unstable. It is the most useful modality if anatomic restenosis is suspected in the setting of stents. CTA Chest CTA is the most useful modality if anatomic restenosis of pulmonary arteries is suspected in the setting of stents or presence of a metal susceptibility artifact that may hamper the use of MRA for this purpose. CTA Coronary Arteries Coronary CTA would be helpful when combined with cardiac CTA if repeat surgery is being considered given the increased rate of coronary anomalies. Congenital or Acquired Heart Disease FDG-PET/CT Heart There is no relevant literature to support the use of FDG-PET/CT heart in the evaluation of TGA after atrial switch. MRA Abdomen There is no relevant literature to support the use of MRA abdomen in the evaluation of TGA after atrial switch.

Congenital or Acquired Heart Disease. Less common complications include pulmonary arterial hypertension, residual VSD, subpulmonary stenosis, and arrhythmias. Arteriography Coronary with Ventriculography Since the coronary arteries are not surgically manipulated during an atrial switch procedure, there is no defined role for coronary arteriography in this setting. In patients with complex coronary anatomy in the setting of TGA, angiography may be helpful to demonstrate dynamic compression and angulation of the coronary arteries in patients with an interarterial course or in those with a muscular bridge [21], but this role has been superseded by CTA in most centers. Arteriography Pulmonary Pulmonary arteriography may be helpful if hemodynamic assessment of pulmonary artery pressure and resistance is required. Pulmonary arteriography is performed during interventions such as branch pulmonary artery balloon dilation and stent placement, to assess for baffle leaks, or narrowing of the systemic or pulmonary venous pathways [21]. CT Heart Function and Morphology CT is an alternative imaging modality to provide incremental information to echocardiography. CT functional assessment is a safer option to CMR in patients who are hemodynamically unstable. It is the most useful modality if anatomic restenosis is suspected in the setting of stents. CTA Chest CTA is the most useful modality if anatomic restenosis of pulmonary arteries is suspected in the setting of stents or presence of a metal susceptibility artifact that may hamper the use of MRA for this purpose. CTA Coronary Arteries Coronary CTA would be helpful when combined with cardiac CTA if repeat surgery is being considered given the increased rate of coronary anomalies. Congenital or Acquired Heart Disease FDG-PET/CT Heart There is no relevant literature to support the use of FDG-PET/CT heart in the evaluation of TGA after atrial switch. MRA Abdomen There is no relevant literature to support the use of MRA abdomen in the evaluation of TGA after atrial switch.

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acrac_3102389_6

Congenital or Acquired Heart Disease

MRA Chest MRA chest provides important information regarding extracardiac structures such as the branch pulmonary arteries, systemic and pulmonary veins, and superior and inferior limb baffles and is used in conjunction with CMR for morphology and function to provide comprehensive evaluation of the cardiovascular system after treatment for TGA. MRA Neck There is no relevant literature to support the use of MRA neck in the evaluation of TGA after atrial switch. MRI Heart Function and Morphology CMR yields accurate and reproducible data regarding ventricular size and function, especially follow-up of systemic RV status and intracardiac baffles. MRI Heart Function with Stress CMR is a the most useful imaging modality to screen for myocardial ischemia, but this is uncommon after atrial switch for TGA because the coronary arteries are not manipulated during surgery. Radiography Chest Radiography of the chest can be used for preliminary assessment of stent position, pacemaker generator and lead position, and as needed during the course of follow-up. SPECT or SPECT/CT MPI Rest and Stress There is no relevant literature to support the use of single-photon emission CT (SPECT)/CT myocardial perfusion imaging (MPI) rest and stress in the evaluation of TGA after atrial switch. US Echocardiography Transesophageal TEE is useful in patients with poor transthoracic acoustic windows, during intraoperative imaging, and in patients (usually adolescents) who require cardioversion for arrhythmia. It is typically used to assess the adequacy of intraoperative repair TTE and may be more sensitive to detect baffle leaks and baffle obstruction. TEE is also helpful to guide catheter-based treatment of pathway obstruction such as balloon dilation, stent placement, or device closure of baffle leaks. Variant 3: Child or adult. Transposition of the great arteries after arterial switch. Incomplete or inadequate assessment of cardiovascular morphology and function after transthoracic echocardiography.

Congenital or Acquired Heart Disease. MRA Chest MRA chest provides important information regarding extracardiac structures such as the branch pulmonary arteries, systemic and pulmonary veins, and superior and inferior limb baffles and is used in conjunction with CMR for morphology and function to provide comprehensive evaluation of the cardiovascular system after treatment for TGA. MRA Neck There is no relevant literature to support the use of MRA neck in the evaluation of TGA after atrial switch. MRI Heart Function and Morphology CMR yields accurate and reproducible data regarding ventricular size and function, especially follow-up of systemic RV status and intracardiac baffles. MRI Heart Function with Stress CMR is a the most useful imaging modality to screen for myocardial ischemia, but this is uncommon after atrial switch for TGA because the coronary arteries are not manipulated during surgery. Radiography Chest Radiography of the chest can be used for preliminary assessment of stent position, pacemaker generator and lead position, and as needed during the course of follow-up. SPECT or SPECT/CT MPI Rest and Stress There is no relevant literature to support the use of single-photon emission CT (SPECT)/CT myocardial perfusion imaging (MPI) rest and stress in the evaluation of TGA after atrial switch. US Echocardiography Transesophageal TEE is useful in patients with poor transthoracic acoustic windows, during intraoperative imaging, and in patients (usually adolescents) who require cardioversion for arrhythmia. It is typically used to assess the adequacy of intraoperative repair TTE and may be more sensitive to detect baffle leaks and baffle obstruction. TEE is also helpful to guide catheter-based treatment of pathway obstruction such as balloon dilation, stent placement, or device closure of baffle leaks. Variant 3: Child or adult. Transposition of the great arteries after arterial switch. Incomplete or inadequate assessment of cardiovascular morphology and function after transthoracic echocardiography.

3102389

acrac_3102389_7

Congenital or Acquired Heart Disease

Next imaging study. The arterial switch operation (ASO) has superseded the Mustard and Senning procedures as the most common surgery performed in D-TGA. In the ASO (Jatene procedure), the ascending aorta and the main pulmonary artery are transected above their valve leaflets and moved to their correct circulatory position (Lecompte maneuver). The coronary arteries are then transplanted from the native aortic root to the neoaortic root (which is the native pulmonary trunk). Septal defects, if present, are surgically closed. Well-known sequelae after an ASO include obstruction of the coronary arteries with related myocardial ischemia, LV dysfunction, narrowing of the pulmonary artery side branches, RVOT obstruction, neoaortic valve insufficiency, and dilatation of the aortic root. RVOT and pulmonary artery stenoses may lead to RV dysfunction necessitating corrective procedures. Supravalvular pulmonary stenosis, particularly in the side branches of the pulmonary arteries, occurs early after an ASO. Dilatation and insufficiency of the neoaortic root usually develops over time. Coronary abnormalities can be present in 8% of asymptomatic individuals on 1- to 20-year follow-up and, although uncommon, can cause sudden death [23]. Noninvasive imaging of the postoperative anatomy is integral to the Congenital or Acquired Heart Disease management of patients who have undergone an ASO. A combination of imaging tests and exercise testing are performed to screen for complications and to assess severity and the need for intervention and the type of intervention. Arteriography Coronary with Ventriculography The coronary artery course has a particularly high variability in patients with TGA. After an ASO, many patients require repeated imaging of their reimplanted coronary arteries. Cardiac catheterization and ventriculography after ASO is reserved for only complex cases in whom incremental information is needed following advanced imaging.

Congenital or Acquired Heart Disease. Next imaging study. The arterial switch operation (ASO) has superseded the Mustard and Senning procedures as the most common surgery performed in D-TGA. In the ASO (Jatene procedure), the ascending aorta and the main pulmonary artery are transected above their valve leaflets and moved to their correct circulatory position (Lecompte maneuver). The coronary arteries are then transplanted from the native aortic root to the neoaortic root (which is the native pulmonary trunk). Septal defects, if present, are surgically closed. Well-known sequelae after an ASO include obstruction of the coronary arteries with related myocardial ischemia, LV dysfunction, narrowing of the pulmonary artery side branches, RVOT obstruction, neoaortic valve insufficiency, and dilatation of the aortic root. RVOT and pulmonary artery stenoses may lead to RV dysfunction necessitating corrective procedures. Supravalvular pulmonary stenosis, particularly in the side branches of the pulmonary arteries, occurs early after an ASO. Dilatation and insufficiency of the neoaortic root usually develops over time. Coronary abnormalities can be present in 8% of asymptomatic individuals on 1- to 20-year follow-up and, although uncommon, can cause sudden death [23]. Noninvasive imaging of the postoperative anatomy is integral to the Congenital or Acquired Heart Disease management of patients who have undergone an ASO. A combination of imaging tests and exercise testing are performed to screen for complications and to assess severity and the need for intervention and the type of intervention. Arteriography Coronary with Ventriculography The coronary artery course has a particularly high variability in patients with TGA. After an ASO, many patients require repeated imaging of their reimplanted coronary arteries. Cardiac catheterization and ventriculography after ASO is reserved for only complex cases in whom incremental information is needed following advanced imaging.

3102389

acrac_3102389_8

Congenital or Acquired Heart Disease

Angiography is performed to assess for coronary artery stenosis after coronary artery reimplantation or during interventional procedures such as branch pulmonary artery balloon dilation and stent placement. In patients with complex coronary anatomy, angiography is useful in demonstrating dynamic compression and angulation of the coronary arteries in patients with an interarterial course or in those with a muscular bridge [21]. Arteriography Pulmonary Pulmonary arteriography is performed during interventions such as branch pulmonary artery balloon dilation and stent placement. CT Heart Function and Morphology CT is an alternative imaging modality to provide incremental information to echocardiography. CT functional assessment is more useful over CMR in patients who are hemodynamically unstable. It is the most useful modality if anatomic restenosis is suspected in the setting of stents. CTA Chest CTA of the chest is useful to study airway compromise, which may happen related to the aortic root or ascending aortic dilatation after ASO. A dynamic CTA may be helpful in this setting to distinguish intrinsic from extrinsic causes of airway obstruction. CTA is the most useful modality if anatomic restenosis of pulmonary arteries is suspected in the setting of stents or presence of a metal susceptibility artifact that may hamper the use of MRA for this purpose. CTA Coronary Arteries Obstructed coronary arteries occur in 8% of survivors and is a common cause of morbidity and mortality after the ASO [23]. ECG-triggered CTA is currently the most useful modality for the primary evaluation of coronary arteries. Its high spatial and temporal resolution allows for the reliable visualization of coronary arteries and screening for potential stenosis, usually without the use of sedation [19,24].

Congenital or Acquired Heart Disease. Angiography is performed to assess for coronary artery stenosis after coronary artery reimplantation or during interventional procedures such as branch pulmonary artery balloon dilation and stent placement. In patients with complex coronary anatomy, angiography is useful in demonstrating dynamic compression and angulation of the coronary arteries in patients with an interarterial course or in those with a muscular bridge [21]. Arteriography Pulmonary Pulmonary arteriography is performed during interventions such as branch pulmonary artery balloon dilation and stent placement. CT Heart Function and Morphology CT is an alternative imaging modality to provide incremental information to echocardiography. CT functional assessment is more useful over CMR in patients who are hemodynamically unstable. It is the most useful modality if anatomic restenosis is suspected in the setting of stents. CTA Chest CTA of the chest is useful to study airway compromise, which may happen related to the aortic root or ascending aortic dilatation after ASO. A dynamic CTA may be helpful in this setting to distinguish intrinsic from extrinsic causes of airway obstruction. CTA is the most useful modality if anatomic restenosis of pulmonary arteries is suspected in the setting of stents or presence of a metal susceptibility artifact that may hamper the use of MRA for this purpose. CTA Coronary Arteries Obstructed coronary arteries occur in 8% of survivors and is a common cause of morbidity and mortality after the ASO [23]. ECG-triggered CTA is currently the most useful modality for the primary evaluation of coronary arteries. Its high spatial and temporal resolution allows for the reliable visualization of coronary arteries and screening for potential stenosis, usually without the use of sedation [19,24].

3102389

acrac_3102389_9

Congenital or Acquired Heart Disease

CT coronary angiography may also be performed as an alternative to coronary catheterization when SPECT/CT MPI shows perfusion deficit or CMR stress perfusion imaging shows ischemia or wall motion abnormality in a vascular distribution [25]. FDG-PET/CT Heart FDG-PET/CT can be used as the alternative method to SPECT/CT MPI for assessing viability when myocardial ischemia is suspected or to assess blood flow to the branch pulmonary arteries after the ASO. FDG-PET/CT can have confirmatory and/or incremental value to TEE and CTA in diagnosing prosthetic endocarditis after RV-PA conduit placement, particularly when anatomic imaging findings are inconclusive or equivocal. MRA Abdomen There is no relevant literature to support the use of MRA abdomen in the evaluation of TGA after arterial switch. MRA Chest MRA chest provides important information regarding extracardiac structures such as the branch pulmonary arteries, ascending aorta, and the aortic arc, and is used in conjunction with CMR for morphology and function to provide comprehensive evaluation of the cardiovascular system after treatment for TGA. MRA Neck There is no relevant literature to support the use of MRA neck in the evaluation of TGA after arterial switch. MRI Heart Function and Morphology CMR yields accurate and reproducible data regarding both LV and RV size and function, differential pulmonary blood flow, neoaortic root diameter and regurgitant blood flow, coronary artery diameter, myocardial perfusion, and myocardial fibrosis. CMR provides important information regarding myocardial performance and viability, as well as quantitative assessment of valvar function and accurate evaluation of conduits [21]. If the echocardiographic Congenital or Acquired Heart Disease assessment of ventricular parameters or the severity of valve regurgitation is in question, CMR can resolve this uncertainty [26].

Congenital or Acquired Heart Disease. CT coronary angiography may also be performed as an alternative to coronary catheterization when SPECT/CT MPI shows perfusion deficit or CMR stress perfusion imaging shows ischemia or wall motion abnormality in a vascular distribution [25]. FDG-PET/CT Heart FDG-PET/CT can be used as the alternative method to SPECT/CT MPI for assessing viability when myocardial ischemia is suspected or to assess blood flow to the branch pulmonary arteries after the ASO. FDG-PET/CT can have confirmatory and/or incremental value to TEE and CTA in diagnosing prosthetic endocarditis after RV-PA conduit placement, particularly when anatomic imaging findings are inconclusive or equivocal. MRA Abdomen There is no relevant literature to support the use of MRA abdomen in the evaluation of TGA after arterial switch. MRA Chest MRA chest provides important information regarding extracardiac structures such as the branch pulmonary arteries, ascending aorta, and the aortic arc, and is used in conjunction with CMR for morphology and function to provide comprehensive evaluation of the cardiovascular system after treatment for TGA. MRA Neck There is no relevant literature to support the use of MRA neck in the evaluation of TGA after arterial switch. MRI Heart Function and Morphology CMR yields accurate and reproducible data regarding both LV and RV size and function, differential pulmonary blood flow, neoaortic root diameter and regurgitant blood flow, coronary artery diameter, myocardial perfusion, and myocardial fibrosis. CMR provides important information regarding myocardial performance and viability, as well as quantitative assessment of valvar function and accurate evaluation of conduits [21]. If the echocardiographic Congenital or Acquired Heart Disease assessment of ventricular parameters or the severity of valve regurgitation is in question, CMR can resolve this uncertainty [26].

3102389

acrac_3102389_10

Congenital or Acquired Heart Disease

The quantitative data on CMR can be validated by comparing the main pulmonary artery flow to the sum of the branch pulmonary artery flows. CMR using 3-D steady-state free precession navigator respiratory gated sequences can noninvasively evaluate the coronary arteries looking for ostial stenoses or proximal kinking and screen for myocardial injury using perfusion and viability sequences [27,28]. MRI Heart Function with Stress CMR is the most useful imaging modality to screen for myocardial ischemia [28]. CMR coronary angiography can provide good resolution images of coronary lumen especially in adolescents and larger children, but it is inferior in comparison with CTA in young children [26]. Myocardial stress perfusion MRI can also be done when there is a concern for ischemia following arterial switch procedure [28,29]. Radiography Chest Radiography of the chest can be used for the preliminary assessment of stent position, pacemaker and lead position, and as needed during the course of follow-up. SPECT or SPECT/CT MPI Rest and Stress Coronary reimplantation during ASO increases the risk of long-term ischemic complications in the postoperative period. SPECT/CT MPI is used when patient symptoms or ECG findings are concerning for myocardial ischemia [30]. US Echocardiography Transesophageal TEE is useful in patients with poor transthoracic acoustic windows, during intraoperative imaging, and in patients (usually adolescents) who require cardioversion for arrhythmia. It is typically used to assess the adequacy of intraoperative repair. If postoperative access to the transthoracic window is limited, TEE can be used to assess the coronary artery origins and flow patterns in the early postoperative period. Arteriography Coronary with Ventriculography Coronary angiography is traditionally reserved for interventional procedures or when noninvasive diagnostic imaging with CT or MRI is inconclusive. It can correctly identify all types of anomalous coronary arteries.

Congenital or Acquired Heart Disease. The quantitative data on CMR can be validated by comparing the main pulmonary artery flow to the sum of the branch pulmonary artery flows. CMR using 3-D steady-state free precession navigator respiratory gated sequences can noninvasively evaluate the coronary arteries looking for ostial stenoses or proximal kinking and screen for myocardial injury using perfusion and viability sequences [27,28]. MRI Heart Function with Stress CMR is the most useful imaging modality to screen for myocardial ischemia [28]. CMR coronary angiography can provide good resolution images of coronary lumen especially in adolescents and larger children, but it is inferior in comparison with CTA in young children [26]. Myocardial stress perfusion MRI can also be done when there is a concern for ischemia following arterial switch procedure [28,29]. Radiography Chest Radiography of the chest can be used for the preliminary assessment of stent position, pacemaker and lead position, and as needed during the course of follow-up. SPECT or SPECT/CT MPI Rest and Stress Coronary reimplantation during ASO increases the risk of long-term ischemic complications in the postoperative period. SPECT/CT MPI is used when patient symptoms or ECG findings are concerning for myocardial ischemia [30]. US Echocardiography Transesophageal TEE is useful in patients with poor transthoracic acoustic windows, during intraoperative imaging, and in patients (usually adolescents) who require cardioversion for arrhythmia. It is typically used to assess the adequacy of intraoperative repair. If postoperative access to the transthoracic window is limited, TEE can be used to assess the coronary artery origins and flow patterns in the early postoperative period. Arteriography Coronary with Ventriculography Coronary angiography is traditionally reserved for interventional procedures or when noninvasive diagnostic imaging with CT or MRI is inconclusive. It can correctly identify all types of anomalous coronary arteries.

3102389

acrac_3102389_11

Congenital or Acquired Heart Disease

However, it lacks optimum 3-D information and the ability to image soft tissue, making it difficult to demonstrate the spatial relationship among the coronary artery course, myocardium, and great vessels. Coronary angiography is essential to clarify the extent of the vulnerable territory of the anomalous vessel (ie, dominant versus nondominant right coronary artery, single coronary, etc). Fractional flow reserve may offer an adjunct to determine the functional significance of AAOCA narrowing or intramyocardial course of the coronary artery, although it is unproven in these settings. Congenital or Acquired Heart Disease In Kawasaki disease, to predict the progress of the disease and determine appropriate treatment and follow-up protocols, it is essential to understand the size and shape of the aneurysms in the early phase. Therefore, traditionally, invasive angiography is performed after the acute stage but, since the advent of CT and MRA invasive coronary angiography, has become second line [33]. Intravascular Ultrasound (IVUS): IVUS affords precise sequential cross-sectional imaging of the coronary lumen and coronary wall thickness with a discriminating power, based on superior spatial resolution. It is particularly useful in stenosis of the anomalous vessel in its intramural course. Arteriography Pulmonary There is no relevant literature to support the use of pulmonary arteriography in the evaluation of suspected or confirmed congenital or acquired coronary artery abnormality. CT Heart Function and Morphology Functional assessment with CT may be considered in the setting of Kawasaki disease for assessment of the consequences of coronary artery compromise. CTA Chest CTA of the chest is rarely helpful for assessment of other vascular involvement in the setting of Kawasaki disease, with axillary artery aneurysms being a common manifestation in the chest.

Congenital or Acquired Heart Disease. However, it lacks optimum 3-D information and the ability to image soft tissue, making it difficult to demonstrate the spatial relationship among the coronary artery course, myocardium, and great vessels. Coronary angiography is essential to clarify the extent of the vulnerable territory of the anomalous vessel (ie, dominant versus nondominant right coronary artery, single coronary, etc). Fractional flow reserve may offer an adjunct to determine the functional significance of AAOCA narrowing or intramyocardial course of the coronary artery, although it is unproven in these settings. Congenital or Acquired Heart Disease In Kawasaki disease, to predict the progress of the disease and determine appropriate treatment and follow-up protocols, it is essential to understand the size and shape of the aneurysms in the early phase. Therefore, traditionally, invasive angiography is performed after the acute stage but, since the advent of CT and MRA invasive coronary angiography, has become second line [33]. Intravascular Ultrasound (IVUS): IVUS affords precise sequential cross-sectional imaging of the coronary lumen and coronary wall thickness with a discriminating power, based on superior spatial resolution. It is particularly useful in stenosis of the anomalous vessel in its intramural course. Arteriography Pulmonary There is no relevant literature to support the use of pulmonary arteriography in the evaluation of suspected or confirmed congenital or acquired coronary artery abnormality. CT Heart Function and Morphology Functional assessment with CT may be considered in the setting of Kawasaki disease for assessment of the consequences of coronary artery compromise. CTA Chest CTA of the chest is rarely helpful for assessment of other vascular involvement in the setting of Kawasaki disease, with axillary artery aneurysms being a common manifestation in the chest.

3102389

acrac_3102389_12

Congenital or Acquired Heart Disease

MRA of the chest and abdomen is more useful to CTA due to its ability to interrogate a wider vascular territory for screening for aneurysms in the setting of Kawasaki disease [34]. CTA Coronary Arteries CTA of coronary arteries is currently the most useful imaging modality for evaluating coronary arteries. Virtual angioscopic view of coronary CTA helps to evaluate anatomic high-risk features, such as the slit-like morphology of the ostium [35]. CT can identify other anatomic high-risk features, such as acute take-off angle, luminal shape, and proximal narrowing of the anomalous coronaries related to the intramural and interarterial course [35]. Coronary CTA, overall, provides a more accurate depiction of the entire anomalous vessel including the distal coronary segments. Coronary CTA is also useful in the setting of Kawasaki disease to screen for the presence and extent of coronary involvement by ectasia, aneurysm, or stenosis and to diagnose and follow-up the presence of mural thrombus in larger aneurysms. FDG-PET/CT Heart There is no relevant literature to support the use of FDG-PET/CT in the evaluation of suspected or confirmed congenital or acquired coronary artery abnormality. MRA Abdomen MRA abdomen is used to screen for extracardiac involvement in Kawasaki disease, with iliac aneurysms being a common manifestation of the disease. MRA Chest MRA chest allows 3-D reconstruction visualization of coronary artery origin and proximal course in AAOCA and the presence of coronary aneurysms in Kawasaki disease, but its spatial resolution is inferior to that of coronary CTA. MRA using 3-D steady-state free precession or 3-D fast gradient echo techniques can be used to evaluate the proximal coronary in AAOCA or the coronary tree in Kawasaki disease. MRA may also be performed with intravenous (IV) contrast to assess the systemic arterial tree for evidence of extracardiac aneurysms in Kawasaki disease [36-38].

Congenital or Acquired Heart Disease. MRA of the chest and abdomen is more useful to CTA due to its ability to interrogate a wider vascular territory for screening for aneurysms in the setting of Kawasaki disease [34]. CTA Coronary Arteries CTA of coronary arteries is currently the most useful imaging modality for evaluating coronary arteries. Virtual angioscopic view of coronary CTA helps to evaluate anatomic high-risk features, such as the slit-like morphology of the ostium [35]. CT can identify other anatomic high-risk features, such as acute take-off angle, luminal shape, and proximal narrowing of the anomalous coronaries related to the intramural and interarterial course [35]. Coronary CTA, overall, provides a more accurate depiction of the entire anomalous vessel including the distal coronary segments. Coronary CTA is also useful in the setting of Kawasaki disease to screen for the presence and extent of coronary involvement by ectasia, aneurysm, or stenosis and to diagnose and follow-up the presence of mural thrombus in larger aneurysms. FDG-PET/CT Heart There is no relevant literature to support the use of FDG-PET/CT in the evaluation of suspected or confirmed congenital or acquired coronary artery abnormality. MRA Abdomen MRA abdomen is used to screen for extracardiac involvement in Kawasaki disease, with iliac aneurysms being a common manifestation of the disease. MRA Chest MRA chest allows 3-D reconstruction visualization of coronary artery origin and proximal course in AAOCA and the presence of coronary aneurysms in Kawasaki disease, but its spatial resolution is inferior to that of coronary CTA. MRA using 3-D steady-state free precession or 3-D fast gradient echo techniques can be used to evaluate the proximal coronary in AAOCA or the coronary tree in Kawasaki disease. MRA may also be performed with intravenous (IV) contrast to assess the systemic arterial tree for evidence of extracardiac aneurysms in Kawasaki disease [36-38].

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acrac_3102389_13

Congenital or Acquired Heart Disease

MRI Heart Function and Morphology CMR offers a wealth of additional relevant information including valvular function, ventricular function, regional contractility, and myocardial viability, all of which could be important considerations during the preoperative evaluation or postoperative follow-up in patients who undergo surgical repair of coronary artery. MRI Heart Function with Stress Pharmacological stress CMR cine and MPI can be performed to assess the functional relevance of a coronary anomaly [36,39]. Congenital or Acquired Heart Disease Radiography Chest There is no relevant literature to support the use of chest radiography in the evaluation of suspected or confirmed congenital or acquired coronary artery abnormality. SPECT or SPECT/CT MPI Rest and Stress Nuclear cardiac imaging modalities play an important role in assessing myocardial perfusion, thus allowing for assessment of the functional relevance of any acquired coronary artery. SPECT MPI and PET MPI may unmask ischemia in asymptomatic and symptomatic patients with anomalous coronary artery [40]. The panel disagreed on SPECT or SPECT/CT MPI rest and stress to screen for myocardial ischemia as the next imaging study after TEE, although its use was supported by expert opinion in centers with pediatric experience with coronary ischemia. US Echocardiography Transesophageal TEE may be useful to visualize coronary artery anatomy perioperatively when the thoracic window is limited. However, TEE is not useful for routine imaging of AAOCA or Kawasaki disease. MRA Neck There is no relevant literature to support the use of MRA neck in the evaluation of suspected or confirmed congenital or acquired coronary artery abnormality. Variant 5: Child. Known single ventricle physiology. Preoperative evaluation for stage 2 single ventricle palliation. Incomplete or inadequate assessment of cardiovascular morphology and function after transthoracic echocardiography. Next imaging study.

Congenital or Acquired Heart Disease. MRI Heart Function and Morphology CMR offers a wealth of additional relevant information including valvular function, ventricular function, regional contractility, and myocardial viability, all of which could be important considerations during the preoperative evaluation or postoperative follow-up in patients who undergo surgical repair of coronary artery. MRI Heart Function with Stress Pharmacological stress CMR cine and MPI can be performed to assess the functional relevance of a coronary anomaly [36,39]. Congenital or Acquired Heart Disease Radiography Chest There is no relevant literature to support the use of chest radiography in the evaluation of suspected or confirmed congenital or acquired coronary artery abnormality. SPECT or SPECT/CT MPI Rest and Stress Nuclear cardiac imaging modalities play an important role in assessing myocardial perfusion, thus allowing for assessment of the functional relevance of any acquired coronary artery. SPECT MPI and PET MPI may unmask ischemia in asymptomatic and symptomatic patients with anomalous coronary artery [40]. The panel disagreed on SPECT or SPECT/CT MPI rest and stress to screen for myocardial ischemia as the next imaging study after TEE, although its use was supported by expert opinion in centers with pediatric experience with coronary ischemia. US Echocardiography Transesophageal TEE may be useful to visualize coronary artery anatomy perioperatively when the thoracic window is limited. However, TEE is not useful for routine imaging of AAOCA or Kawasaki disease. MRA Neck There is no relevant literature to support the use of MRA neck in the evaluation of suspected or confirmed congenital or acquired coronary artery abnormality. Variant 5: Child. Known single ventricle physiology. Preoperative evaluation for stage 2 single ventricle palliation. Incomplete or inadequate assessment of cardiovascular morphology and function after transthoracic echocardiography. Next imaging study.

3102389

acrac_3102389_14

Congenital or Acquired Heart Disease

Single ventricle lesions are congenital heart anomalies in which one of the 2 ventricular chambers is either absent or so severely hypoplastic that a biventricular repair is impossible. Typically, the atrioventricular valve associated with the absent or hypoplastic ventricle is also absent or hypoplastic. The arterial outflow valve associated with the absent/hypoplastic ventricle is also frequently affected. Single ventricle congenital heart defects cover a wide spectrum including the following: hypoplastic left heart syndrome, tricuspid atresia, unbalanced atrioventricular, pulmonary atresia with intact ventricular septum, Ebstein anomaly, and double outlet left ventricle. The repair of this entity involves 3-staged reconstruction to establish a circulatory system wherein all the deoxygenated blood flows directly into the lungs, bypassing the heart, while the oxygenated blood goes to the functional single ventricle to be pumped out to the systemic circulation. Stage 1 of this repair involves optimizing the pulmonary arterial blood flow, sometimes with a systemic-pulmonary arterial shunt or pulmonary artery band, and is performed shortly after birth. This procedure allows postoperative recovery and growth until stage 2 palliation can be performed. The stage 2 procedure, otherwise known as superior cavopulmonary connection, involves establishing a connection between the systemic venous return from the upper half of the body and the pulmonary arteries to allow deoxygenated blood flow into the pulmonary circulation. Some procedures in stage 2 are bidirectional Glenn, hemi-Fontan, and Kawashima operations. This procedure is typically performed within 6 months of birth. The primary goals of the imaging evaluation before the stage 2 operation include an assessment for obstruction in the pulmonary arteries and veins, the atrial septal defect, ventricular outflow tract, and aortic arch; for the degree and mechanism of valve regurgitation; and ventricular size and function.

Congenital or Acquired Heart Disease. Single ventricle lesions are congenital heart anomalies in which one of the 2 ventricular chambers is either absent or so severely hypoplastic that a biventricular repair is impossible. Typically, the atrioventricular valve associated with the absent or hypoplastic ventricle is also absent or hypoplastic. The arterial outflow valve associated with the absent/hypoplastic ventricle is also frequently affected. Single ventricle congenital heart defects cover a wide spectrum including the following: hypoplastic left heart syndrome, tricuspid atresia, unbalanced atrioventricular, pulmonary atresia with intact ventricular septum, Ebstein anomaly, and double outlet left ventricle. The repair of this entity involves 3-staged reconstruction to establish a circulatory system wherein all the deoxygenated blood flows directly into the lungs, bypassing the heart, while the oxygenated blood goes to the functional single ventricle to be pumped out to the systemic circulation. Stage 1 of this repair involves optimizing the pulmonary arterial blood flow, sometimes with a systemic-pulmonary arterial shunt or pulmonary artery band, and is performed shortly after birth. This procedure allows postoperative recovery and growth until stage 2 palliation can be performed. The stage 2 procedure, otherwise known as superior cavopulmonary connection, involves establishing a connection between the systemic venous return from the upper half of the body and the pulmonary arteries to allow deoxygenated blood flow into the pulmonary circulation. Some procedures in stage 2 are bidirectional Glenn, hemi-Fontan, and Kawashima operations. This procedure is typically performed within 6 months of birth. The primary goals of the imaging evaluation before the stage 2 operation include an assessment for obstruction in the pulmonary arteries and veins, the atrial septal defect, ventricular outflow tract, and aortic arch; for the degree and mechanism of valve regurgitation; and ventricular size and function.

3102389

acrac_3102389_15

Congenital or Acquired Heart Disease

Another role of imaging could be to decide if the ventricular volumes and functions still support the patient proceeding down the single ventricle pathway or if the patient is a candidate for a 1.5-ventricle or 2-ventricle repair. A crucial role of imaging in this setting is to demonstrate the pulmonary arterial anatomy, including the distal branches, to evaluate for anatomic obstruction that may impact the Glenn circulation. Knowledge of branch pulmonary artery anatomy adds significantly to the surgical planning process. A complete anatomic assessment of the branch pulmonary arteries to detect stenoses should be performed in all patients undergoing stage 2 repair. Arteriography Coronary with Ventriculography Direct cardiac catheterization and angiography has historically been the standard of care for assessing hemodynamic and anatomic suitability before stage 2 repair. Its routine use is decreasing since the advent of advanced CMR and CT methods. The use of catheter angiography is supported in the literature [41]; for example, in patients with pulmonary atresia and intact ventricular septum, the diagnosis of RV dependent coronary circulation is established by RV and selective coronary angiography and has an important impact upon surgical approach. Congenital or Acquired Heart Disease One of the advantages of cardiac catheterization before bidirectional Glenn operation is that anomalies such as systemic-to-pulmonary collateral vessels and aortic coarctation can be palliated using transcatheter techniques. It particularly pertinent for those who have undergone prior stage 1 palliation with aortic arch reconstruction, which is associated with a 10% to 15% incidence of recurrent coarctation at the distal end of the arch reconstruction [42]. Arteriography Pulmonary Cardiac catheterization is useful for the imaging evaluation before stage 2 repair to assess pulmonary arterial anatomy before surgical repair [41].

Congenital or Acquired Heart Disease. Another role of imaging could be to decide if the ventricular volumes and functions still support the patient proceeding down the single ventricle pathway or if the patient is a candidate for a 1.5-ventricle or 2-ventricle repair. A crucial role of imaging in this setting is to demonstrate the pulmonary arterial anatomy, including the distal branches, to evaluate for anatomic obstruction that may impact the Glenn circulation. Knowledge of branch pulmonary artery anatomy adds significantly to the surgical planning process. A complete anatomic assessment of the branch pulmonary arteries to detect stenoses should be performed in all patients undergoing stage 2 repair. Arteriography Coronary with Ventriculography Direct cardiac catheterization and angiography has historically been the standard of care for assessing hemodynamic and anatomic suitability before stage 2 repair. Its routine use is decreasing since the advent of advanced CMR and CT methods. The use of catheter angiography is supported in the literature [41]; for example, in patients with pulmonary atresia and intact ventricular septum, the diagnosis of RV dependent coronary circulation is established by RV and selective coronary angiography and has an important impact upon surgical approach. Congenital or Acquired Heart Disease One of the advantages of cardiac catheterization before bidirectional Glenn operation is that anomalies such as systemic-to-pulmonary collateral vessels and aortic coarctation can be palliated using transcatheter techniques. It particularly pertinent for those who have undergone prior stage 1 palliation with aortic arch reconstruction, which is associated with a 10% to 15% incidence of recurrent coarctation at the distal end of the arch reconstruction [42]. Arteriography Pulmonary Cardiac catheterization is useful for the imaging evaluation before stage 2 repair to assess pulmonary arterial anatomy before surgical repair [41].

3102389

acrac_3102389_16

Congenital or Acquired Heart Disease

Routine cardiac catheterization is less frequently performed before undertaking stage 2 repair, but it has a useful role in the assessment of hemodynamic suitability to adapt to this type of circulation by directly measuring pulmonary vascular resistance. CTA Chest CTA chest is a useful modality and provides accurate means of evaluation of pulmonary arterial anatomy and pulmonary and systemic venous status before stage 2 repair. Thrombosis of the systemic-to-pulmonary arterial shunt may occur in 6% to 17% of cases and constitutes a surgical emergency [44]. CTA can be used as the confirmatory test especially if echocardiography is inconclusive. MRA Abdomen There is no relevant literature to support the use of MRA abdomen in the evaluation of known single ventricle physiology. MRA Chest MRA chest is an excellent imaging technique for the evaluation of pulmonary arterial anatomy before stage 2 repair. It has the advantage that it can be easily combined with MRI heart function and morphology for a complete evaluation of the single ventricle patient. MRA has great diagnostic utility compared with echocardiography and is accurate in comparison to catheter angiography for the diagnosis of pulmonary artery stenoses. MRA Neck There is no relevant literature to support the use of MRA neck in the evaluation of known single ventricle physiology. MRI Heart Function and Morphology CMR allows for the quantification of ventricular volume and function, with abnormal ventricular morphology [42]. This can be useful in decisions regarding stage 1, 1.5, or 2 ventricle repair. MRI Heart Function with Stress There is no relevant literature to support the use of MRI heart function with stress in the evaluation of known single ventricle physiology. Radiography Chest Other than evaluation of patent ductus arteriosus or aortopulmonary shunt stent positioning, there is no relevant literature to support the use of radiography chest in the evaluation of known single ventricle physiology.

Congenital or Acquired Heart Disease. Routine cardiac catheterization is less frequently performed before undertaking stage 2 repair, but it has a useful role in the assessment of hemodynamic suitability to adapt to this type of circulation by directly measuring pulmonary vascular resistance. CTA Chest CTA chest is a useful modality and provides accurate means of evaluation of pulmonary arterial anatomy and pulmonary and systemic venous status before stage 2 repair. Thrombosis of the systemic-to-pulmonary arterial shunt may occur in 6% to 17% of cases and constitutes a surgical emergency [44]. CTA can be used as the confirmatory test especially if echocardiography is inconclusive. MRA Abdomen There is no relevant literature to support the use of MRA abdomen in the evaluation of known single ventricle physiology. MRA Chest MRA chest is an excellent imaging technique for the evaluation of pulmonary arterial anatomy before stage 2 repair. It has the advantage that it can be easily combined with MRI heart function and morphology for a complete evaluation of the single ventricle patient. MRA has great diagnostic utility compared with echocardiography and is accurate in comparison to catheter angiography for the diagnosis of pulmonary artery stenoses. MRA Neck There is no relevant literature to support the use of MRA neck in the evaluation of known single ventricle physiology. MRI Heart Function and Morphology CMR allows for the quantification of ventricular volume and function, with abnormal ventricular morphology [42]. This can be useful in decisions regarding stage 1, 1.5, or 2 ventricle repair. MRI Heart Function with Stress There is no relevant literature to support the use of MRI heart function with stress in the evaluation of known single ventricle physiology. Radiography Chest Other than evaluation of patent ductus arteriosus or aortopulmonary shunt stent positioning, there is no relevant literature to support the use of radiography chest in the evaluation of known single ventricle physiology.

3102389

acrac_3102389_17

Congenital or Acquired Heart Disease

SPECT or SPECT/CT MPI Rest and Stress There is no relevant literature to support the use of SPECT or SPECT/CT MPI rest and stress in the evaluation of known single ventricle physiology. Congenital or Acquired Heart Disease FDG-PET/CT Heart There is no relevant literature to support the use of FDG-PET/CT heart in the evaluation of known single ventricle physiology. US Echocardiography Transesophageal TEE may provide useful information before, during, or after surgery for stage 2 palliation regarding pulmonary arterial or pulmonary venous flow patterns, severity of atrioventricular valve regurgitation, atrial shunt, and cardiac thrombus. Variant 6: Child. Known single ventricle physiology. Preoperative evaluation for stage 3 single ventricle palliation (total cavopulmonary connection). Incomplete or inadequate assessment of cardiovascular morphology and function after transthoracic echocardiography. Next imaging study. The Fontan operation for single ventricle patients is the procedure in which a conduit (the total cavopulmonary connection) is placed to channel the remaining systemic venous return (including the hepatic veins) into the pulmonary arteries. The aim of the diagnostic evaluation before Fontan is to identify those few patients in whom the Fontan operation should not be performed and those who require additional intervention before or at the time of Fontan. The main consideration before Fontan procedure is elevated pulmonary artery pressure, which determines the prognosis during the postoperative course. However, with the modern stage 2 repair techniques, pulmonary resistance is seldom an important issue at the pre-Fontan stage. Arteriography Coronary with Ventriculography Cardiac catheterizations are done when elevated pulmonary artery pressure or elevated ventricular filling pressure is suspected.

Congenital or Acquired Heart Disease. SPECT or SPECT/CT MPI Rest and Stress There is no relevant literature to support the use of SPECT or SPECT/CT MPI rest and stress in the evaluation of known single ventricle physiology. Congenital or Acquired Heart Disease FDG-PET/CT Heart There is no relevant literature to support the use of FDG-PET/CT heart in the evaluation of known single ventricle physiology. US Echocardiography Transesophageal TEE may provide useful information before, during, or after surgery for stage 2 palliation regarding pulmonary arterial or pulmonary venous flow patterns, severity of atrioventricular valve regurgitation, atrial shunt, and cardiac thrombus. Variant 6: Child. Known single ventricle physiology. Preoperative evaluation for stage 3 single ventricle palliation (total cavopulmonary connection). Incomplete or inadequate assessment of cardiovascular morphology and function after transthoracic echocardiography. Next imaging study. The Fontan operation for single ventricle patients is the procedure in which a conduit (the total cavopulmonary connection) is placed to channel the remaining systemic venous return (including the hepatic veins) into the pulmonary arteries. The aim of the diagnostic evaluation before Fontan is to identify those few patients in whom the Fontan operation should not be performed and those who require additional intervention before or at the time of Fontan. The main consideration before Fontan procedure is elevated pulmonary artery pressure, which determines the prognosis during the postoperative course. However, with the modern stage 2 repair techniques, pulmonary resistance is seldom an important issue at the pre-Fontan stage. Arteriography Coronary with Ventriculography Cardiac catheterizations are done when elevated pulmonary artery pressure or elevated ventricular filling pressure is suspected.

3102389

acrac_3102389_18

Congenital or Acquired Heart Disease

Cardiac catheterization also provides an opportunity for interventional procedures before the Fontan operation consisted of embolization of aortopulmonary collateral vessels [45]. Other important indications for cardiac catheterization include severe atrioventricular valve regurgitation semiquantitatively evaluated by means of echo color Doppler, suspected pulmonary vein stenosis at echo or CMR, suspected pulmonary pathway or Glenn anastomosis obstruction, or suspected significant venovenous collaterals at MRA [46]. Arteriography Pulmonary Pulmonary arteriography is performed after echocardiography when there is a suspicion of branch pulmonary artery stenosis because smaller pulmonary arteries are not optimally seen on echocardiography. CTA Chest Pulmonary embolism and thrombosis are known complications in patients undergoing single ventricle palliation. CTA is an effective method for diagnosis of pulmonary embolism in patients presenting with symptoms suspicious for pulmonary embolism [48]. CTA Coronary Arteries There is no relevant literature to support the use of CTA coronary arteries in the evaluation of known single ventricle physiology. MRI Heart Function and Morphology Routine preoperative imaging before Fontan procedure is obtained using CMR for anatomy and to determine the current hemodynamics and physiology [49,50]. CMR is a comprehensive modality for accurate assessment of ventricular function, pulmonary artery, pulmonary venous return, cavopulmonary anastomosis, aortic arch, valves, and any valvular regurgitation. Congenital or Acquired Heart Disease MRA Chest MRA chest provides good assessment of branch pulmonary arteries, their caliber, and presence of thrombus within but often fails to visualize very small aortopulmonary collaterals that may require preoperative embolization. MRA Neck There is no relevant literature to support the use of MRA neck in the evaluation of known single ventricle physiology.

Congenital or Acquired Heart Disease. Cardiac catheterization also provides an opportunity for interventional procedures before the Fontan operation consisted of embolization of aortopulmonary collateral vessels [45]. Other important indications for cardiac catheterization include severe atrioventricular valve regurgitation semiquantitatively evaluated by means of echo color Doppler, suspected pulmonary vein stenosis at echo or CMR, suspected pulmonary pathway or Glenn anastomosis obstruction, or suspected significant venovenous collaterals at MRA [46]. Arteriography Pulmonary Pulmonary arteriography is performed after echocardiography when there is a suspicion of branch pulmonary artery stenosis because smaller pulmonary arteries are not optimally seen on echocardiography. CTA Chest Pulmonary embolism and thrombosis are known complications in patients undergoing single ventricle palliation. CTA is an effective method for diagnosis of pulmonary embolism in patients presenting with symptoms suspicious for pulmonary embolism [48]. CTA Coronary Arteries There is no relevant literature to support the use of CTA coronary arteries in the evaluation of known single ventricle physiology. MRI Heart Function and Morphology Routine preoperative imaging before Fontan procedure is obtained using CMR for anatomy and to determine the current hemodynamics and physiology [49,50]. CMR is a comprehensive modality for accurate assessment of ventricular function, pulmonary artery, pulmonary venous return, cavopulmonary anastomosis, aortic arch, valves, and any valvular regurgitation. Congenital or Acquired Heart Disease MRA Chest MRA chest provides good assessment of branch pulmonary arteries, their caliber, and presence of thrombus within but often fails to visualize very small aortopulmonary collaterals that may require preoperative embolization. MRA Neck There is no relevant literature to support the use of MRA neck in the evaluation of known single ventricle physiology.

3102389

acrac_3102389_19

Congenital or Acquired Heart Disease

MRI Heart Function with Stress There is no relevant literature to support the use of MRI heart function with stress in the evaluation of known single ventricle physiology. Radiography Chest Other than evaluation of device or stent positioning, there is no relevant literature to support the use of radiography chest in the evaluation of known single ventricle physiology. SPECT or SPECT/CT MPI Rest and Stress There is no relevant literature to support the use of SPECT or SPECT/CT MPI rest and stress in the evaluation of known single ventricle physiology. FDG-PET/CT Heart There is no relevant literature to support the use of FDG-PET/CT heart in the evaluation of known single ventricle physiology. US Echocardiography Transesophageal TEE may provide useful information before, during, or after surgery for stage 3 palliation regarding pulmonary arterial or pulmonary venous flow patterns, severity of atrioventricular valve regurgitation, atrial shunt, and cardiac thrombus. Variant 7: Child or adult. Known single ventricle physiology. Postoperative evaluation after stage 3 single inadequate assessment of ventricle palliation (total cavopulmonary connection). Incomplete or cardiovascular morphology and function after transthoracic echocardiography. Next imaging study. Stage 3 repair for single ventricle palliation involves baffling of all systemic venous drainage directly to the pulmonary arteries, known as total cavopulmonary connection or Fontan operation. This is typically performed between 2 to 4 years of age and most commonly consists of either a lateral tunnel intracardiac baffle or an extracardiac conduit, with or without a fenestration. The Fontan operation also ensures that hepatic blood flow is directed into the lungs via the pulmonary arteries, thus preventing the formation of pulmonary arteriovenous malformations. Today, the estimates of 20-year survival for survivors of the Fontan procedure vary between 61% and 85% [51].

Congenital or Acquired Heart Disease. MRI Heart Function with Stress There is no relevant literature to support the use of MRI heart function with stress in the evaluation of known single ventricle physiology. Radiography Chest Other than evaluation of device or stent positioning, there is no relevant literature to support the use of radiography chest in the evaluation of known single ventricle physiology. SPECT or SPECT/CT MPI Rest and Stress There is no relevant literature to support the use of SPECT or SPECT/CT MPI rest and stress in the evaluation of known single ventricle physiology. FDG-PET/CT Heart There is no relevant literature to support the use of FDG-PET/CT heart in the evaluation of known single ventricle physiology. US Echocardiography Transesophageal TEE may provide useful information before, during, or after surgery for stage 3 palliation regarding pulmonary arterial or pulmonary venous flow patterns, severity of atrioventricular valve regurgitation, atrial shunt, and cardiac thrombus. Variant 7: Child or adult. Known single ventricle physiology. Postoperative evaluation after stage 3 single inadequate assessment of ventricle palliation (total cavopulmonary connection). Incomplete or cardiovascular morphology and function after transthoracic echocardiography. Next imaging study. Stage 3 repair for single ventricle palliation involves baffling of all systemic venous drainage directly to the pulmonary arteries, known as total cavopulmonary connection or Fontan operation. This is typically performed between 2 to 4 years of age and most commonly consists of either a lateral tunnel intracardiac baffle or an extracardiac conduit, with or without a fenestration. The Fontan operation also ensures that hepatic blood flow is directed into the lungs via the pulmonary arteries, thus preventing the formation of pulmonary arteriovenous malformations. Today, the estimates of 20-year survival for survivors of the Fontan procedure vary between 61% and 85% [51].

3102389

acrac_3102389_20

Congenital or Acquired Heart Disease

Early diagnosis and management of complications associated with Fontan physiology hold the most promise for improving longevity. Imaging after stage 3 repair can assess anatomy, ventricular and valve function, blood flow, and myocardial fibrosis. Anatomic considerations include the presence of thrombus in the circuit, the patency of the extracardiac conduit, stenoses within the caval veins and pulmonary arteries, and the size and location of aortopulmonary collaterals and venovenous collaterals. Considerations for assessment of flow include quantification of the degree of aortopulmonary and venovenous collateralization, the relative flow within the 2 branch pulmonary arteries, and valvular regurgitation. Considerations for assessment of ventricular function and morphology include screening for systolic and diastolic dysfunction, ventricular type and shape, and myocardial characterization. Arteriography Coronary with Ventriculography Clinical indications for this examination include investigating symptoms associated with decreased ventricular function such as unexplained volume retention, fatigue, exercise limitation, and cyanosis. Cardiac catheterization with coronary angiography can evaluate coronary artery anatomy, and ventriculography can be used to estimate the function of the single ventricle and valvular flow. Cardiac catheterization is also helpful to assess the presence and severity of aortopulmonary, systemic-pulmonary venous, and systemic venovenous collaterals and also provides access to perform embolization of clinically significant collaterals. Cardiac catheterization is also suggested in the Congenital or Acquired Heart Disease assessment of patients with failing Fontan physiology and features of Fontan-associated liver disease. Imaging of a patent fenestration is seen well with direct angiography on cardiac catheterization [52].

Congenital or Acquired Heart Disease. Early diagnosis and management of complications associated with Fontan physiology hold the most promise for improving longevity. Imaging after stage 3 repair can assess anatomy, ventricular and valve function, blood flow, and myocardial fibrosis. Anatomic considerations include the presence of thrombus in the circuit, the patency of the extracardiac conduit, stenoses within the caval veins and pulmonary arteries, and the size and location of aortopulmonary collaterals and venovenous collaterals. Considerations for assessment of flow include quantification of the degree of aortopulmonary and venovenous collateralization, the relative flow within the 2 branch pulmonary arteries, and valvular regurgitation. Considerations for assessment of ventricular function and morphology include screening for systolic and diastolic dysfunction, ventricular type and shape, and myocardial characterization. Arteriography Coronary with Ventriculography Clinical indications for this examination include investigating symptoms associated with decreased ventricular function such as unexplained volume retention, fatigue, exercise limitation, and cyanosis. Cardiac catheterization with coronary angiography can evaluate coronary artery anatomy, and ventriculography can be used to estimate the function of the single ventricle and valvular flow. Cardiac catheterization is also helpful to assess the presence and severity of aortopulmonary, systemic-pulmonary venous, and systemic venovenous collaterals and also provides access to perform embolization of clinically significant collaterals. Cardiac catheterization is also suggested in the Congenital or Acquired Heart Disease assessment of patients with failing Fontan physiology and features of Fontan-associated liver disease. Imaging of a patent fenestration is seen well with direct angiography on cardiac catheterization [52].

3102389

acrac_3102389_21

Congenital or Acquired Heart Disease

Arteriography Pulmonary Cardiac catheterization for pulmonary angiography can be performed when pulmonary artery stenosis is detected on echocardiography or MRI and pulmonary artery angioplasty is indicated [52]. CT Heart Function and Morphology CT heart function and morphology is indicated when MRI is limited by the presence of significant metallic susceptibility artifact obscuring the heart or due to the presence of MR-incompatible pacemakers/devices. CTA Chest CTA is useful for assessment of anatomy after stage 3 repair. Anatomic considerations include the presence of thrombus in the circuit, the patency of the extracardiac conduit, stenoses within the caval veins and pulmonary arteries, and the size and location of aortopulmonary collaterals and venovenous collaterals [52,53]. After Fontan surgery, imaging of coronaries, systemic arteries, and Fontan circuit require different timing and dose considerations, and dedicated contrast injection and scanning protocols designed for the Fontan circulation are needed to optimize the study [48]. CTA Coronary Arteries CTA of the coronary arteries is useful and allows for high spatial resolution evaluation of coronary artery anatomy in patients after stage 3 repair [52]. FDG-PET/CT Heart There is no role for routine performance of FDG-PET imaging after stage 3 palliation in single ventricle. FDG- PET/CT of the heart can be performed in the setting of changes of clinical status that might indicate underlying cardiac dysfunction. MRA Abdomen There is no relevant literature to support the use of MRA abdomen after stage 3 repair. MRA Chest MRA chest can provide accurate anatomic characterization of stage 3 repair. Anatomic considerations include the presence of thrombus in the circuit, the patency of the extracardiac conduit, stenoses within the caval veins and pulmonary arteries, and the size and location of aortopulmonary collaterals and venovenous collaterals [52,53].

Congenital or Acquired Heart Disease. Arteriography Pulmonary Cardiac catheterization for pulmonary angiography can be performed when pulmonary artery stenosis is detected on echocardiography or MRI and pulmonary artery angioplasty is indicated [52]. CT Heart Function and Morphology CT heart function and morphology is indicated when MRI is limited by the presence of significant metallic susceptibility artifact obscuring the heart or due to the presence of MR-incompatible pacemakers/devices. CTA Chest CTA is useful for assessment of anatomy after stage 3 repair. Anatomic considerations include the presence of thrombus in the circuit, the patency of the extracardiac conduit, stenoses within the caval veins and pulmonary arteries, and the size and location of aortopulmonary collaterals and venovenous collaterals [52,53]. After Fontan surgery, imaging of coronaries, systemic arteries, and Fontan circuit require different timing and dose considerations, and dedicated contrast injection and scanning protocols designed for the Fontan circulation are needed to optimize the study [48]. CTA Coronary Arteries CTA of the coronary arteries is useful and allows for high spatial resolution evaluation of coronary artery anatomy in patients after stage 3 repair [52]. FDG-PET/CT Heart There is no role for routine performance of FDG-PET imaging after stage 3 palliation in single ventricle. FDG- PET/CT of the heart can be performed in the setting of changes of clinical status that might indicate underlying cardiac dysfunction. MRA Abdomen There is no relevant literature to support the use of MRA abdomen after stage 3 repair. MRA Chest MRA chest can provide accurate anatomic characterization of stage 3 repair. Anatomic considerations include the presence of thrombus in the circuit, the patency of the extracardiac conduit, stenoses within the caval veins and pulmonary arteries, and the size and location of aortopulmonary collaterals and venovenous collaterals [52,53].

3102389

acrac_3102389_22

Congenital or Acquired Heart Disease

Gadolinium-enhanced CMR angiography has been demonstrated to be more accurate in the diagnosis of a collateral vessels in comparison to catheter angiography and offers promise to plan transcatheter interventions in those who prove to have clinically significant collateral vessels. Of note, MRA chest has lower spatial resolution compared with CTA chest for small vessels such as the coronary arteries [52]. MRA Neck There is no relevant literature to support the use of MRA neck after stage 3 repair. MRI Heart Function and Morphology CMR is used regularly in addition to echocardiography for long-term monitoring of Fontan patients. MRI for heart function and morphology is helpful in assessment of anatomy, ventricular and valve function, flows, and myocardial fibrosis. It allows for estimating ventricular function, quantifying valvular regurgitation, quantifying pulmonary and systemic blood flow, and aortopulmonary collaterals [54]. Late gadolinium enhancement CMR is used to detect myocardial fibrosis and infarction [55]. Phase-contrast MRA flow measurements in the branch pulmonary arteries are useful for the quantification of differential pulmonary blood flow in the Fontan patient compared with nuclear scintigraphy, due to venous streaming effects on caval flows [53]. Four-dimensional flow, with or without the use of blood pool contrast agents, has been used to simplify, accelerate, and abbreviate the MR scanning protocol in these patients [56]. MRI Heart Function with Stress There is no role for routine performance of vasodilator stress perfusion after stage 3 palliation in single ventricle. There is some evidence that vasodilator stress perfusion MRI can be used to assess latent diastolic dysfunction after stage 3 repair [57,58]. Congenital or Acquired Heart Disease Radiography Chest There is no relevant literature to support the routine use of chest radiography after stage 3 palliation in single ventricle.

Congenital or Acquired Heart Disease. Gadolinium-enhanced CMR angiography has been demonstrated to be more accurate in the diagnosis of a collateral vessels in comparison to catheter angiography and offers promise to plan transcatheter interventions in those who prove to have clinically significant collateral vessels. Of note, MRA chest has lower spatial resolution compared with CTA chest for small vessels such as the coronary arteries [52]. MRA Neck There is no relevant literature to support the use of MRA neck after stage 3 repair. MRI Heart Function and Morphology CMR is used regularly in addition to echocardiography for long-term monitoring of Fontan patients. MRI for heart function and morphology is helpful in assessment of anatomy, ventricular and valve function, flows, and myocardial fibrosis. It allows for estimating ventricular function, quantifying valvular regurgitation, quantifying pulmonary and systemic blood flow, and aortopulmonary collaterals [54]. Late gadolinium enhancement CMR is used to detect myocardial fibrosis and infarction [55]. Phase-contrast MRA flow measurements in the branch pulmonary arteries are useful for the quantification of differential pulmonary blood flow in the Fontan patient compared with nuclear scintigraphy, due to venous streaming effects on caval flows [53]. Four-dimensional flow, with or without the use of blood pool contrast agents, has been used to simplify, accelerate, and abbreviate the MR scanning protocol in these patients [56]. MRI Heart Function with Stress There is no role for routine performance of vasodilator stress perfusion after stage 3 palliation in single ventricle. There is some evidence that vasodilator stress perfusion MRI can be used to assess latent diastolic dysfunction after stage 3 repair [57,58]. Congenital or Acquired Heart Disease Radiography Chest There is no relevant literature to support the routine use of chest radiography after stage 3 palliation in single ventricle.

3102389

acrac_3102389_23

Congenital or Acquired Heart Disease

However, chest radiography may be used to screen for the location of devices and metallic implants that are placed in this patient population. SPECT or SPECT/CT MPI Rest and Stress There is no role for routine performance of vasodilator stress perfusion after stage 3 palliation in single ventricle. SPECT or SPECT/CT MPI rest and stress tests are used in the setting of changes of clinical status that might indicate underlying cardiac dysfunction. US Echocardiography Transesophageal TEE can be used for comprehensive evaluation of the heart and central vascular anatomy, ventricular and valvular function, and flows in areas that are difficult to assess by TTE. One area in which it is better than TTE is in the detection of intracardiac thrombus. Variant 8: Child or adult. Known or suspected anomalous pulmonary venous return with inadequate evaluation after transthoracic echocardiography. Next imaging study. Total anomalous pulmonary venous connection (TAPVC) refers to the condition in which all of the pulmonary veins drain into the right atrium, either directly or indirectly through other systemic pathways. TAPVC is rare, with prevalence estimated at approximately 0.01% [59]. The contexts of imaging in TAPVC management are to define the surgical anatomy, when one or more pulmonary veins are not visualized by TTE, a TTE showing right-sided cardiac chamber dilation with unclear delineation of the pulmonary venous anatomy, when obstruction is suspected, or when there is an associated abnormality like a varix that is not characterized adequately by TTE. There is also an important role for imaging in the postoperative period after TAPVC repair to screen for recurrent obstruction. Partial anomalous pulmonary venous connection (PAPVC) is where one or more pulmonary veins drains into the right atrium, either directly or indirectly. PAPVC is more common with a prevalence at approximately 1% [59]. PAPVC has a few common variants.

Congenital or Acquired Heart Disease. However, chest radiography may be used to screen for the location of devices and metallic implants that are placed in this patient population. SPECT or SPECT/CT MPI Rest and Stress There is no role for routine performance of vasodilator stress perfusion after stage 3 palliation in single ventricle. SPECT or SPECT/CT MPI rest and stress tests are used in the setting of changes of clinical status that might indicate underlying cardiac dysfunction. US Echocardiography Transesophageal TEE can be used for comprehensive evaluation of the heart and central vascular anatomy, ventricular and valvular function, and flows in areas that are difficult to assess by TTE. One area in which it is better than TTE is in the detection of intracardiac thrombus. Variant 8: Child or adult. Known or suspected anomalous pulmonary venous return with inadequate evaluation after transthoracic echocardiography. Next imaging study. Total anomalous pulmonary venous connection (TAPVC) refers to the condition in which all of the pulmonary veins drain into the right atrium, either directly or indirectly through other systemic pathways. TAPVC is rare, with prevalence estimated at approximately 0.01% [59]. The contexts of imaging in TAPVC management are to define the surgical anatomy, when one or more pulmonary veins are not visualized by TTE, a TTE showing right-sided cardiac chamber dilation with unclear delineation of the pulmonary venous anatomy, when obstruction is suspected, or when there is an associated abnormality like a varix that is not characterized adequately by TTE. There is also an important role for imaging in the postoperative period after TAPVC repair to screen for recurrent obstruction. Partial anomalous pulmonary venous connection (PAPVC) is where one or more pulmonary veins drains into the right atrium, either directly or indirectly. PAPVC is more common with a prevalence at approximately 1% [59]. PAPVC has a few common variants.

3102389

acrac_3102389_24

Congenital or Acquired Heart Disease

The most common form is where the left upper pulmonary vein connects to the left brachiocephalic vein into the superior vena cava. Another type is where the right upper pulmonary veins connect directly into the superior vena cava, which is commonly associated with other left to right shunts, including atrial septal and superior sinus venosus defects. Another unique variant of PAPVC is Scimitar syndrome, in which part or all of the right pulmonary veins connect to the inferior vena cava through the diaphragm. The right lung is often hypoplastic and/or has anomalous bronchial or arterial anatomy in addition to the PAPVC. The ultimate management of PAPVC is usually surgical correction, but unlike TAPVC, this does not always happen shortly after birth due to delayed diagnosis or mild symptoms. Advanced imaging in diagnosis of PAPVC is usually requested in the setting in which a TTE shows right-sided cardiac chamber dilation with unclear delineation of the pulmonary venous anatomy. The role of imaging in PAPVC management is to confirm the diagnosis, define the surgical anatomy, and quantify the shunt to help decide on need for and timing of intervention. Arteriography Coronary with Ventriculography Cardiac catheterization was traditionally the imaging modality used for the diagnosis of TAPVC and PAPVC; however, it has mostly been replaced by less invasive modalities [60]. Cardiac catheterization can be used to demonstrate the anatomy and quantify the degree of shunting using oximetry. However, cardiac catheterization has been shown by some studies to be less accurate in the setting of PAPVC [61]. Occasionally, simultaneous depiction of systemic and pulmonary vascular systems may be difficult in catheter angiography due to overlapping views of adjacent vascular structures. Moreover, it carries high risk of mortality in obstructive TAPVC.

Congenital or Acquired Heart Disease. The most common form is where the left upper pulmonary vein connects to the left brachiocephalic vein into the superior vena cava. Another type is where the right upper pulmonary veins connect directly into the superior vena cava, which is commonly associated with other left to right shunts, including atrial septal and superior sinus venosus defects. Another unique variant of PAPVC is Scimitar syndrome, in which part or all of the right pulmonary veins connect to the inferior vena cava through the diaphragm. The right lung is often hypoplastic and/or has anomalous bronchial or arterial anatomy in addition to the PAPVC. The ultimate management of PAPVC is usually surgical correction, but unlike TAPVC, this does not always happen shortly after birth due to delayed diagnosis or mild symptoms. Advanced imaging in diagnosis of PAPVC is usually requested in the setting in which a TTE shows right-sided cardiac chamber dilation with unclear delineation of the pulmonary venous anatomy. The role of imaging in PAPVC management is to confirm the diagnosis, define the surgical anatomy, and quantify the shunt to help decide on need for and timing of intervention. Arteriography Coronary with Ventriculography Cardiac catheterization was traditionally the imaging modality used for the diagnosis of TAPVC and PAPVC; however, it has mostly been replaced by less invasive modalities [60]. Cardiac catheterization can be used to demonstrate the anatomy and quantify the degree of shunting using oximetry. However, cardiac catheterization has been shown by some studies to be less accurate in the setting of PAPVC [61]. Occasionally, simultaneous depiction of systemic and pulmonary vascular systems may be difficult in catheter angiography due to overlapping views of adjacent vascular structures. Moreover, it carries high risk of mortality in obstructive TAPVC.

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acrac_3102389_25

Congenital or Acquired Heart Disease

The main role for a cardiac catheterization is now in the rare patient with TAPVC who requires interventional cardiac palliation before complete repair, such as atrial septostomy or stent placement [62,63]. Arteriography Pulmonary There is no relevant literature to support the use of pulmonary arteriography in the evaluation of known or suspected anomalous pulmonary venous return with inadequate evaluation after TTE. CT Heart Function and Morphology CT heart function and morphology is indicated when MRI is limited by the presence of significant metallic susceptibility artifact obscuring the heart or due to the presence of MR-incompatible pacemakers/devices. Congenital or Acquired Heart Disease CTA Chest CTA chest is useful for the anatomical definition of anomalous pulmonary venous drainage anatomy. CTA chest can also be used in the critical setting of possible obstructed TAPVC to define the level and degree of obstruction, especially in children with infracardiac and mixed TAPVC [64,65]. In obstructed infradiaphragmatic TAPVC, CTA chest can correctly depict the drainage site of the common pulmonary vein, stenosis of the vertical vein, and the course of the atypical vessel into the systemic vein, especially outside the usual echocardiographic windows [66]. In other types of TAPVC and PAPVC, CTA chest has excellent spatial resolution and can help define the complete anomalous drainage pathways of the pulmonary veins. CTA chest has the added advantage of being an excellent modality for evaluating the pulmonary parenchyma to look for associated pulmonary and bronchovascular abnormalities (eg, pulmonary sequestration, hypoplastic lung, abnormal bronchial branching) [64,67,68]. CTA Coronary Arteries There is no relevant literature to support the use of CTA coronary arteries in the evaluation of known or suspected anomalous pulmonary venous return with inadequate evaluation after TTE.

Congenital or Acquired Heart Disease. The main role for a cardiac catheterization is now in the rare patient with TAPVC who requires interventional cardiac palliation before complete repair, such as atrial septostomy or stent placement [62,63]. Arteriography Pulmonary There is no relevant literature to support the use of pulmonary arteriography in the evaluation of known or suspected anomalous pulmonary venous return with inadequate evaluation after TTE. CT Heart Function and Morphology CT heart function and morphology is indicated when MRI is limited by the presence of significant metallic susceptibility artifact obscuring the heart or due to the presence of MR-incompatible pacemakers/devices. Congenital or Acquired Heart Disease CTA Chest CTA chest is useful for the anatomical definition of anomalous pulmonary venous drainage anatomy. CTA chest can also be used in the critical setting of possible obstructed TAPVC to define the level and degree of obstruction, especially in children with infracardiac and mixed TAPVC [64,65]. In obstructed infradiaphragmatic TAPVC, CTA chest can correctly depict the drainage site of the common pulmonary vein, stenosis of the vertical vein, and the course of the atypical vessel into the systemic vein, especially outside the usual echocardiographic windows [66]. In other types of TAPVC and PAPVC, CTA chest has excellent spatial resolution and can help define the complete anomalous drainage pathways of the pulmonary veins. CTA chest has the added advantage of being an excellent modality for evaluating the pulmonary parenchyma to look for associated pulmonary and bronchovascular abnormalities (eg, pulmonary sequestration, hypoplastic lung, abnormal bronchial branching) [64,67,68]. CTA Coronary Arteries There is no relevant literature to support the use of CTA coronary arteries in the evaluation of known or suspected anomalous pulmonary venous return with inadequate evaluation after TTE.

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acrac_3102389_26

Congenital or Acquired Heart Disease

MRA Abdomen Vascular imaging of the abdomen may be helpful in the cases of infracardiac TAPVC or PAPVC to demonstrate the drainage of pulmonary vein into hepatic vein or portal vein. It may be needed to assess the resulting complications such as portal venous system aneurysm formation and collaterals. MRA Chest MRA chest is excellent at identifying the anatomy, specifically the anomalous course and connections of the pulmonary veins [68,69]. A small case study showed that MRA chest was more accurate than both echocardiography and cardiac catheterization in accurately identifying the anomalous veins in 7 patients with TAPVC [70]. MRI Heart Function and Morphology MRI heart function and morphology is complementary to MRA chest and can be performed during the same imaging session. MRI heart function and morphology is useful in cases of PAPVC, because it is the ideal noninvasive modality to quantify the shunt amount by means flow rate assessment, ventricular muscle masses, and ventricular volumes and function [68,71]. The shunt quantification is usually performed using phase-contrast imaging through the aorta and pulmonary vein. MRI Heart Function with Stress There is no relevant literature to support the use of MRI heart function with stress in the evaluation of known or suspected anomalous pulmonary venous return with inadequate evaluation after TTE. MRA Neck There is no relevant literature to support the use of MRA neck in the evaluation of known or suspected anomalous pulmonary venous return with inadequate evaluation after TTE. Radiography Chest Chest radiography may demonstrate additional findings such as associated dextrocardia, signs of vascular congestion, and pulmonary edema, which may point towards obstructed TAPVC [65]. FDG-PET/CT Heart There is no relevant literature to support the use of FDG-PET/CT heart in the evaluation of known or suspected anomalous pulmonary venous return with inadequate evaluation after TTE.

Congenital or Acquired Heart Disease. MRA Abdomen Vascular imaging of the abdomen may be helpful in the cases of infracardiac TAPVC or PAPVC to demonstrate the drainage of pulmonary vein into hepatic vein or portal vein. It may be needed to assess the resulting complications such as portal venous system aneurysm formation and collaterals. MRA Chest MRA chest is excellent at identifying the anatomy, specifically the anomalous course and connections of the pulmonary veins [68,69]. A small case study showed that MRA chest was more accurate than both echocardiography and cardiac catheterization in accurately identifying the anomalous veins in 7 patients with TAPVC [70]. MRI Heart Function and Morphology MRI heart function and morphology is complementary to MRA chest and can be performed during the same imaging session. MRI heart function and morphology is useful in cases of PAPVC, because it is the ideal noninvasive modality to quantify the shunt amount by means flow rate assessment, ventricular muscle masses, and ventricular volumes and function [68,71]. The shunt quantification is usually performed using phase-contrast imaging through the aorta and pulmonary vein. MRI Heart Function with Stress There is no relevant literature to support the use of MRI heart function with stress in the evaluation of known or suspected anomalous pulmonary venous return with inadequate evaluation after TTE. MRA Neck There is no relevant literature to support the use of MRA neck in the evaluation of known or suspected anomalous pulmonary venous return with inadequate evaluation after TTE. Radiography Chest Chest radiography may demonstrate additional findings such as associated dextrocardia, signs of vascular congestion, and pulmonary edema, which may point towards obstructed TAPVC [65]. FDG-PET/CT Heart There is no relevant literature to support the use of FDG-PET/CT heart in the evaluation of known or suspected anomalous pulmonary venous return with inadequate evaluation after TTE.

3102389

acrac_3102389_27

Congenital or Acquired Heart Disease

SPECT or SPECT/CT MPI Rest and Stress There is no relevant literature to support the use of SPECT or SPECT/CT MPI rest and stress in the evaluation of known or suspected anomalous pulmonary venous return with inadequate evaluation after TTE. US Echocardiography Transesophageal TEE can be used in cases of PAPVC in which TTE does not completely delineate the partial veins and cardiac chamber enlargement [72,73]. However, the procedure is more invasive than CT or MRI, and it can suffer from Congenital or Acquired Heart Disease airways obscuring some of the acoustic windows, especially for anomalous venous drainage that occurs superior to the right atrium. TEE is also less accurate than MRI for some pulmonary vein anatomy and shunt quantification [72]. TEE has just recently been shown to be safe in patients with TAPVC, but only after median sternotomy [74]. There is no published role for TEE as the most useful imaging modality after an insufficient TTE with suspicion for TAPVC. Variant 9: Child or adult. Suspected aortic coarctation with inadequate evaluation after transthoracic echocardiography. Next imaging study. Coarctation of aorta (CoA) refers to discrete or diffuse narrowing in the aorta causing obstruction to the flow of blood. It accounts for 6% to 8% of all CHDs [75]. Aortic coarctation can be more commonly associated with other cardiac lesions such as bicuspid aortic valve, aortic arch hypoplasia, aberrant aortic branch vessels, and other intracardiac and conotruncal defects. This variant will focus on imaging recommendations for aortic coarctation and associated aortic arch pathology. If a patient has associated intracardiac or conotruncal abnormalities, please refer to those variants for recommendations on how to image those concurrent diseases. Aortic coarctation is managed by surgical treatment, transcatheter balloon angioplasty, and transcatheter stent placement.

Congenital or Acquired Heart Disease. SPECT or SPECT/CT MPI Rest and Stress There is no relevant literature to support the use of SPECT or SPECT/CT MPI rest and stress in the evaluation of known or suspected anomalous pulmonary venous return with inadequate evaluation after TTE. US Echocardiography Transesophageal TEE can be used in cases of PAPVC in which TTE does not completely delineate the partial veins and cardiac chamber enlargement [72,73]. However, the procedure is more invasive than CT or MRI, and it can suffer from Congenital or Acquired Heart Disease airways obscuring some of the acoustic windows, especially for anomalous venous drainage that occurs superior to the right atrium. TEE is also less accurate than MRI for some pulmonary vein anatomy and shunt quantification [72]. TEE has just recently been shown to be safe in patients with TAPVC, but only after median sternotomy [74]. There is no published role for TEE as the most useful imaging modality after an insufficient TTE with suspicion for TAPVC. Variant 9: Child or adult. Suspected aortic coarctation with inadequate evaluation after transthoracic echocardiography. Next imaging study. Coarctation of aorta (CoA) refers to discrete or diffuse narrowing in the aorta causing obstruction to the flow of blood. It accounts for 6% to 8% of all CHDs [75]. Aortic coarctation can be more commonly associated with other cardiac lesions such as bicuspid aortic valve, aortic arch hypoplasia, aberrant aortic branch vessels, and other intracardiac and conotruncal defects. This variant will focus on imaging recommendations for aortic coarctation and associated aortic arch pathology. If a patient has associated intracardiac or conotruncal abnormalities, please refer to those variants for recommendations on how to image those concurrent diseases. Aortic coarctation is managed by surgical treatment, transcatheter balloon angioplasty, and transcatheter stent placement.

3102389

acrac_3102389_28

Congenital or Acquired Heart Disease

Arteriography Coronary with Ventriculography Before advances in echocardiography, cardiac catheterization was the mainstay for making the diagnosis of CoA. The pressure gradient across the coarctation segment and the collateral vascularity can be accurately assessed with direct angiography. In the current era, it is primarily used when as catheter-based investigation such as balloon angioplasty or stent insertion are being considered [76]. Arteriography Pulmonary There is no relevant literature to support the use of pulmonary arteriography in the evaluation of known or suspected aortic coarctation. CT Heart Function and Morphology There is no relevant literature to support the use of CT heart function and morphology in the evaluation of suspected aortic coarctation, although its use was supported in adults by expert opinion in situations in which TEE windows are inadequate. The panel agreed that CT for function is not useful for a child in this clinical scenario. CTA Chest CTA chest is a complementary imaging modality in patients with suspected aortic coarctation after echocardiography. In patients with suboptimal arch imaging with echocardiography, CTA chest works as a great tool to assist with surgical planning [77-79]. Aortic coarctation is often associated with a hypoplastic aortic arch, and CTA chest is helpful in identifying the severity of arch hypoplasia, the length of the hypoplasia, and the relative origins of the aortic arch branch vessels in relation to the coarctation and arch hypoplasia [79]. CTA Coronary Arteries There is no relevant literature to support the use of CTA coronary arteries in the evaluation of suspected aortic coarctation. MRA Abdomen There is no relevant literature to support the use of MRA abdomen in the evaluation of suspected aortic coarctation. MRA Chest MRA chest can be used as the second line of imaging after echocardiography in young children who do not require sedation and adolescents [79,80].

Congenital or Acquired Heart Disease. Arteriography Coronary with Ventriculography Before advances in echocardiography, cardiac catheterization was the mainstay for making the diagnosis of CoA. The pressure gradient across the coarctation segment and the collateral vascularity can be accurately assessed with direct angiography. In the current era, it is primarily used when as catheter-based investigation such as balloon angioplasty or stent insertion are being considered [76]. Arteriography Pulmonary There is no relevant literature to support the use of pulmonary arteriography in the evaluation of known or suspected aortic coarctation. CT Heart Function and Morphology There is no relevant literature to support the use of CT heart function and morphology in the evaluation of suspected aortic coarctation, although its use was supported in adults by expert opinion in situations in which TEE windows are inadequate. The panel agreed that CT for function is not useful for a child in this clinical scenario. CTA Chest CTA chest is a complementary imaging modality in patients with suspected aortic coarctation after echocardiography. In patients with suboptimal arch imaging with echocardiography, CTA chest works as a great tool to assist with surgical planning [77-79]. Aortic coarctation is often associated with a hypoplastic aortic arch, and CTA chest is helpful in identifying the severity of arch hypoplasia, the length of the hypoplasia, and the relative origins of the aortic arch branch vessels in relation to the coarctation and arch hypoplasia [79]. CTA Coronary Arteries There is no relevant literature to support the use of CTA coronary arteries in the evaluation of suspected aortic coarctation. MRA Abdomen There is no relevant literature to support the use of MRA abdomen in the evaluation of suspected aortic coarctation. MRA Chest MRA chest can be used as the second line of imaging after echocardiography in young children who do not require sedation and adolescents [79,80].

3102389

acrac_3102389_29

Congenital or Acquired Heart Disease

One advantage of MRA chest is that it can be combined with MRI heart function and morphology to quantify the degree of collaterals around the coarctation, more accurately estimate pressure gradients across the coarctation, and assess associated cardiac and conotruncal abnormalities [81,82]. MRI Heart Function and Morphology MRI heart function and morphology can quantify the degree of collaterals around the coarctation. It can also be easily combined with an MRA chest to provide more comprehensive evaluation in patients with aortic coractation and associated cardiac and conotruncal abnormalities [75]. Congenital or Acquired Heart Disease MRI Heart Function with Stress There is no relevant literature to support the additional use of MRI heart function with stress in the evaluation of suspected aortic coarctation. MRA Neck There is no relevant literature to support the use of MRA neck in the evaluation of suspected aortic coarctation. Radiography Chest Radiography chest has limited clinical utility in diagnosis. Conventional signs on the chest radiograph may be subtle and not always easy to appreciate but may provide clues about the presence of an aortic coarctation. SPECT or SPECT/CT MPI Rest and Stress There is no relevant literature to support the use of SPECT or SPECT/CT MPI rest and stress in the evaluation of suspected aortic coarctation. FDG-PET/CT Heart There is no relevant literature to support the use of FDG-PET/CT heart in the evaluation of suspected aortic coarctation. US Echocardiography Transesophageal TEE is used for intraoperative imaging when other cardiac abnormalities are present in conjunction with CoA. The role of TEE for Doppler examination is limited because the ultrasound beam is almost perpendicular to the line of blood flow, leading to inaccuracies in velocity estimation.

Congenital or Acquired Heart Disease. One advantage of MRA chest is that it can be combined with MRI heart function and morphology to quantify the degree of collaterals around the coarctation, more accurately estimate pressure gradients across the coarctation, and assess associated cardiac and conotruncal abnormalities [81,82]. MRI Heart Function and Morphology MRI heart function and morphology can quantify the degree of collaterals around the coarctation. It can also be easily combined with an MRA chest to provide more comprehensive evaluation in patients with aortic coractation and associated cardiac and conotruncal abnormalities [75]. Congenital or Acquired Heart Disease MRI Heart Function with Stress There is no relevant literature to support the additional use of MRI heart function with stress in the evaluation of suspected aortic coarctation. MRA Neck There is no relevant literature to support the use of MRA neck in the evaluation of suspected aortic coarctation. Radiography Chest Radiography chest has limited clinical utility in diagnosis. Conventional signs on the chest radiograph may be subtle and not always easy to appreciate but may provide clues about the presence of an aortic coarctation. SPECT or SPECT/CT MPI Rest and Stress There is no relevant literature to support the use of SPECT or SPECT/CT MPI rest and stress in the evaluation of suspected aortic coarctation. FDG-PET/CT Heart There is no relevant literature to support the use of FDG-PET/CT heart in the evaluation of suspected aortic coarctation. US Echocardiography Transesophageal TEE is used for intraoperative imaging when other cardiac abnormalities are present in conjunction with CoA. The role of TEE for Doppler examination is limited because the ultrasound beam is almost perpendicular to the line of blood flow, leading to inaccuracies in velocity estimation.

3102389

acrac_3102389_30

Congenital or Acquired Heart Disease

Common manifestation of Marfan syndrome include annuloaortic ectasia with or without aortic valve insufficiency, aortic dissection, aortic aneurysm, pulmonary artery dilatation, and mitral valve prolapse. Aortic root aneurysms are present in up to 98% of patients with Loeys-Dietz syndrome, with thoracic aortic dissection being the leading cause of death (67%), followed by abdominal aortic dissection. Arterial tortuosity is a distinguishing feature of Loeys-Dietz syndrome, and there is a propensity for involvement of the extracranial carotid arteries and vertebral arteries [83]. Other cardiovascular abnormalities described in Loeys-Dietz syndrome include coronary artery aneurysms, pulmonary artery aneurysms, and aneurysms of the ductus arteriosus. Ehlers-Danlos syndrome also predisposes to aortic dissections. Nearly 25% of people with bicuspid aortic valve may experience severe aortic valve dysfunction, ascending aortic aneurysm, cardiac death, hospital admission for heart failure, and aortic dissection or rupture [84]. Children with aortopathy require regular imaging surveillance to measure the aortic diameter, status of the aortic valve, and cardiac functional status. Current surgical mandate is based on aortic diameter cutoffs to decide the time of surgical intervention [85,86]. The guidelines from the American Heart Association provide thresholds for prophylactic replacement of the aorta, based primarily on aortic diameter or rapid aortic enlargement [87,88]. Arteriography Coronary with Ventriculography Coronary artery ectasia can be an associated finding in many connective tissue diseases like bicuspid aortic valve [89], Marfan syndrome, and systemic lupus erythematosus. Coronary arteriography has been useful for imaging, but in current practice, it is used only if coronary CTA or coronary MRA provide insufficient information.

Congenital or Acquired Heart Disease. Common manifestation of Marfan syndrome include annuloaortic ectasia with or without aortic valve insufficiency, aortic dissection, aortic aneurysm, pulmonary artery dilatation, and mitral valve prolapse. Aortic root aneurysms are present in up to 98% of patients with Loeys-Dietz syndrome, with thoracic aortic dissection being the leading cause of death (67%), followed by abdominal aortic dissection. Arterial tortuosity is a distinguishing feature of Loeys-Dietz syndrome, and there is a propensity for involvement of the extracranial carotid arteries and vertebral arteries [83]. Other cardiovascular abnormalities described in Loeys-Dietz syndrome include coronary artery aneurysms, pulmonary artery aneurysms, and aneurysms of the ductus arteriosus. Ehlers-Danlos syndrome also predisposes to aortic dissections. Nearly 25% of people with bicuspid aortic valve may experience severe aortic valve dysfunction, ascending aortic aneurysm, cardiac death, hospital admission for heart failure, and aortic dissection or rupture [84]. Children with aortopathy require regular imaging surveillance to measure the aortic diameter, status of the aortic valve, and cardiac functional status. Current surgical mandate is based on aortic diameter cutoffs to decide the time of surgical intervention [85,86]. The guidelines from the American Heart Association provide thresholds for prophylactic replacement of the aorta, based primarily on aortic diameter or rapid aortic enlargement [87,88]. Arteriography Coronary with Ventriculography Coronary artery ectasia can be an associated finding in many connective tissue diseases like bicuspid aortic valve [89], Marfan syndrome, and systemic lupus erythematosus. Coronary arteriography has been useful for imaging, but in current practice, it is used only if coronary CTA or coronary MRA provide insufficient information.

3102389

acrac_3102389_31

Congenital or Acquired Heart Disease

Arteriography Pulmonary Pulmonary arteriography is seldom required for diagnosis or surveillance of pulmonary artery dilatation which can occur in Marfan syndrome. CTA Chest CTA chest may be used for imaging surveillance to measure the aortic diameter, and to screen for involvement of the arterial tree in the chest. CTA is especially useful in the emergent setting. ECG gating is critical for accurate assessment of the aortic root. CTA Coronary Arteries CTA is the most useful modality for the evaluation of coronary ectasia or aneurysms, which are often seen in the setting of connective tissue diseases. The diagnostic utility of CTA is very useful compared to coronary MRA in terms of spatial resolution and shorter scan duration. FDG-PET/CT Heart There is no relevant literature to support the use of FDG-PET/CT heart in the evaluation of suspected aortopathy or connective tissue disorder. MRA Chest MRA is the most useful modality for aortic assessment when TTE is suboptimal for assessment of aortopathy in pediatric patients due to its ability to screen multiple territories with the same contrast injection, including the head, neck, chest, and abdomen. To avoid multiple administrations of gadolinium-based contrast agents, follow-up imaging of the aortic root may be performed with noncontrast MRA techniques like cine gradient echo and navigator respiratory gated 3-D steady-state free precession. MRA may offer further valuable information, when complemented with phase-contrast flow data in bicuspid aortic valve, about the possibility of associated valvular regurgitation and alterations in shear stress that may predispose to progressive dilation [91-93]. MRA Neck MRA neck is frequently performed at the same setting as MRA chest to screen for extracardiac vascular involvement in connective tissue disease and in all cases of aortopathy to measure vertebral artery tortuosity, which is used as a prognostic marker to determine risk of aortic dissection [94].

Congenital or Acquired Heart Disease. Arteriography Pulmonary Pulmonary arteriography is seldom required for diagnosis or surveillance of pulmonary artery dilatation which can occur in Marfan syndrome. CTA Chest CTA chest may be used for imaging surveillance to measure the aortic diameter, and to screen for involvement of the arterial tree in the chest. CTA is especially useful in the emergent setting. ECG gating is critical for accurate assessment of the aortic root. CTA Coronary Arteries CTA is the most useful modality for the evaluation of coronary ectasia or aneurysms, which are often seen in the setting of connective tissue diseases. The diagnostic utility of CTA is very useful compared to coronary MRA in terms of spatial resolution and shorter scan duration. FDG-PET/CT Heart There is no relevant literature to support the use of FDG-PET/CT heart in the evaluation of suspected aortopathy or connective tissue disorder. MRA Chest MRA is the most useful modality for aortic assessment when TTE is suboptimal for assessment of aortopathy in pediatric patients due to its ability to screen multiple territories with the same contrast injection, including the head, neck, chest, and abdomen. To avoid multiple administrations of gadolinium-based contrast agents, follow-up imaging of the aortic root may be performed with noncontrast MRA techniques like cine gradient echo and navigator respiratory gated 3-D steady-state free precession. MRA may offer further valuable information, when complemented with phase-contrast flow data in bicuspid aortic valve, about the possibility of associated valvular regurgitation and alterations in shear stress that may predispose to progressive dilation [91-93]. MRA Neck MRA neck is frequently performed at the same setting as MRA chest to screen for extracardiac vascular involvement in connective tissue disease and in all cases of aortopathy to measure vertebral artery tortuosity, which is used as a prognostic marker to determine risk of aortic dissection [94].

3102389

acrac_69449_0

Hemoptysis

Initial Imaging Definition Imaging is considered at the beginning of the care episode for the medical condition defined by the variant. More than one procedure can be considered usually appropriate in the initial imaging evaluation when: aRadiology Imaging Associates, Englewood, Colorado. bResearch Author, Keck School of Medicine of USC, Los Angeles, California. cPanel Chair, Vanderbilt University Medical Center, Nashville, Tennessee. dPanel Vice-Chair, University of California San Francisco, San Francisco, California. eStanford University Medical Center, Stanford, California; The Society of Thoracic Surgeons. fSchmidt College of Medicine, Florida Atlantic University, Boca Raton, Florida. gUniversity of Southern California, Los Angeles, California. hBeaumont Health System, Royal Oak, Michigan: American College of Emergency Physicians. iNaval Medical Center Portsmouth, Portsmouth, Virginia. jUniversity of Iowa Hospitals and Clinics, Iowa City, Iowa. kVanderbilt University Medical Center, Nashville, Tennessee; American College of Chest Physicians. lUniversity of Wisconsin, Madison, Wisconsin. mMallinckrodt Institute of Radiology, Saint Louis, Missouri. nJohn H. Stroger, Jr. Hospital of Cook County, Chicago, Illinois; American College of Physicians. oDuke University School of Medicine, Durham, North Carolina; The Society of Thoracic Surgeons. pThe University of Texas MD Anderson Cancer Center, Houston, Texas. qSpecialty Chair, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin. 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] All elements are essential: 1) timing, 2) reconstructions/reformats, and 3) 3-D renderings.

Hemoptysis. Initial Imaging Definition Imaging is considered at the beginning of the care episode for the medical condition defined by the variant. More than one procedure can be considered usually appropriate in the initial imaging evaluation when: aRadiology Imaging Associates, Englewood, Colorado. bResearch Author, Keck School of Medicine of USC, Los Angeles, California. cPanel Chair, Vanderbilt University Medical Center, Nashville, Tennessee. dPanel Vice-Chair, University of California San Francisco, San Francisco, California. eStanford University Medical Center, Stanford, California; The Society of Thoracic Surgeons. fSchmidt College of Medicine, Florida Atlantic University, Boca Raton, Florida. gUniversity of Southern California, Los Angeles, California. hBeaumont Health System, Royal Oak, Michigan: American College of Emergency Physicians. iNaval Medical Center Portsmouth, Portsmouth, Virginia. jUniversity of Iowa Hospitals and Clinics, Iowa City, Iowa. kVanderbilt University Medical Center, Nashville, Tennessee; American College of Chest Physicians. lUniversity of Wisconsin, Madison, Wisconsin. mMallinckrodt Institute of Radiology, Saint Louis, Missouri. nJohn H. Stroger, Jr. Hospital of Cook County, Chicago, Illinois; American College of Physicians. oDuke University School of Medicine, Durham, North Carolina; The Society of Thoracic Surgeons. pThe University of Texas MD Anderson Cancer Center, Houston, Texas. qSpecialty Chair, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin. 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] All elements are essential: 1) timing, 2) reconstructions/reformats, and 3) 3-D renderings.

69449

acrac_69449_1

Hemoptysis

Standard CTs with contrast also include timing issues and recons/reformats. Only in CTA, however, is 3-D rendering a required element. This corresponds to the definitions that CMS has applied to the Current Procedural Terminology codes. Massive hemoptysis due to an unknown cause (ie, cryptogenic hemoptysis) has similar BAE outcomes compared with hemoptysis from a known cause. An early study treating cryptogenic hemoptysis with BAE was published in 2010 [22]. In this study, 39 patients with cryptogenic hemoptysis who presented with varying severity of hemorrhage were all treated medically. Hemoptysis remained uncontrolled in 21 patients, who subsequently underwent successful BAE; 2 patients had recurrent hemoptysis. A second retrospective review compared BAE outcomes of 26 patients with cryptogenic hemoptysis to 152 patients with a known cause of hemoptysis over the same interval. Both groups showed a 100% immediate success rate following BAE, and both groups demonstrated similar recurrence rates (12% versus 25%, respectively, which was not statistically different) [8]. Over 90% of massive hemoptysis is due to a systemic arterial supply, and therefore conventional pulmonary arteriography is rarely performed. An early study documenting this was authored by Sbano et al [23], reporting a pulmonary arterial bleeding origin in 8 of 76 patients with massive hemoptysis. Although all of these patients were initially treated with BAE, 7 out of 8 patients required additional pulmonary artery embolization. Shin et al [24] identified 10 patients with pulmonary artery pseudoaneurysms (PAPs) out of 286 patients presenting with massive hemoptysis undergoing BAE. These authors reported a pulmonary artery embolization success rate above 90%. Khalil et al [25] retrospectively reviewed 272 patients, 13 of whom had bleeding from a pulmonary artery origin. Of these 13 patients, 11 underwent pulmonary artery embolization, all of which were successful.

Hemoptysis. Standard CTs with contrast also include timing issues and recons/reformats. Only in CTA, however, is 3-D rendering a required element. This corresponds to the definitions that CMS has applied to the Current Procedural Terminology codes. Massive hemoptysis due to an unknown cause (ie, cryptogenic hemoptysis) has similar BAE outcomes compared with hemoptysis from a known cause. An early study treating cryptogenic hemoptysis with BAE was published in 2010 [22]. In this study, 39 patients with cryptogenic hemoptysis who presented with varying severity of hemorrhage were all treated medically. Hemoptysis remained uncontrolled in 21 patients, who subsequently underwent successful BAE; 2 patients had recurrent hemoptysis. A second retrospective review compared BAE outcomes of 26 patients with cryptogenic hemoptysis to 152 patients with a known cause of hemoptysis over the same interval. Both groups showed a 100% immediate success rate following BAE, and both groups demonstrated similar recurrence rates (12% versus 25%, respectively, which was not statistically different) [8]. Over 90% of massive hemoptysis is due to a systemic arterial supply, and therefore conventional pulmonary arteriography is rarely performed. An early study documenting this was authored by Sbano et al [23], reporting a pulmonary arterial bleeding origin in 8 of 76 patients with massive hemoptysis. Although all of these patients were initially treated with BAE, 7 out of 8 patients required additional pulmonary artery embolization. Shin et al [24] identified 10 patients with pulmonary artery pseudoaneurysms (PAPs) out of 286 patients presenting with massive hemoptysis undergoing BAE. These authors reported a pulmonary artery embolization success rate above 90%. Khalil et al [25] retrospectively reviewed 272 patients, 13 of whom had bleeding from a pulmonary artery origin. Of these 13 patients, 11 underwent pulmonary artery embolization, all of which were successful.

69449

acrac_69449_2

Hemoptysis

The largest study to date isolating patients with massive hemoptysis due to a pulmonary arterial source identified 24 patients from a cohort of 712 patients presenting with massive hemoptysis [26]. This study reported an 88% pulmonary artery embolization success rate. Overall, BAE is now universally accepted as a safe and effective intervention for the treatment of massive hemoptysis. CT Chest with IV Contrast The utility of CT in determining the cause for hemoptysis was first established in the late 1990s. Naidich et al [27] reported CT-bronchoscopic correlations of 58 patients with hemoptysis (severity not specified), showing CT was superior to bronchoscopy in both the diagnosis of lung cancer (17 CT positive versus 15 bronchoscopy positive) and definitive staging of lung cancer (48% versus 14%, respectively). They also established that CT was superior to radiography. Of the 23 normal chest radiographs, subsequent CT provided a definitive cause in 9 patients. Revel et al [28] published data from 80 patients with massive hemoptysis demonstrating CT was more efficient than the previous reference standard of bronchoscopy in identifying the etiology of hemoptysis (77% versus 8%, respectively; P < . 001). Based on these studies, CT can facilitate BAE planning by potentially identifying a specific lesion or isolating the bleeding artery based on increased arterial diameter and wall irregularity in a high percentage of cases. CT Chest without IV Contrast Several early studies have established the use of CT in the diagnosis of hemoptysis used high-resolution CT (HRCT). For example, Tsoumakidou et al [32] followed 184 patients with varying degrees of hemoptysis, demonstrating that HRCT identified a cause in 41% of patients with a normal chest radiograph. In 2008, Khalil et al [25] reported on the utility of performing HRCT in the emergent management of hemoptysis in the intensive care unit.

Hemoptysis. The largest study to date isolating patients with massive hemoptysis due to a pulmonary arterial source identified 24 patients from a cohort of 712 patients presenting with massive hemoptysis [26]. This study reported an 88% pulmonary artery embolization success rate. Overall, BAE is now universally accepted as a safe and effective intervention for the treatment of massive hemoptysis. CT Chest with IV Contrast The utility of CT in determining the cause for hemoptysis was first established in the late 1990s. Naidich et al [27] reported CT-bronchoscopic correlations of 58 patients with hemoptysis (severity not specified), showing CT was superior to bronchoscopy in both the diagnosis of lung cancer (17 CT positive versus 15 bronchoscopy positive) and definitive staging of lung cancer (48% versus 14%, respectively). They also established that CT was superior to radiography. Of the 23 normal chest radiographs, subsequent CT provided a definitive cause in 9 patients. Revel et al [28] published data from 80 patients with massive hemoptysis demonstrating CT was more efficient than the previous reference standard of bronchoscopy in identifying the etiology of hemoptysis (77% versus 8%, respectively; P < . 001). Based on these studies, CT can facilitate BAE planning by potentially identifying a specific lesion or isolating the bleeding artery based on increased arterial diameter and wall irregularity in a high percentage of cases. CT Chest without IV Contrast Several early studies have established the use of CT in the diagnosis of hemoptysis used high-resolution CT (HRCT). For example, Tsoumakidou et al [32] followed 184 patients with varying degrees of hemoptysis, demonstrating that HRCT identified a cause in 41% of patients with a normal chest radiograph. In 2008, Khalil et al [25] reported on the utility of performing HRCT in the emergent management of hemoptysis in the intensive care unit.

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Hemoptysis

With the advancement of technology, the vast majority of CT examinations can be reformatted to the resolution of the previously ordered HRCT, and there is rarely an added benefit of HRCT to a routine CT. Khalil et al [33] subsequently published a study retrospectively evaluating patient outcomes comparing a cohort of patients who had a CT without IV contrast with a cohort of patients who underwent CTA. There was a statistically significant difference in the number of emergent surgical resections following embolization in patients who did not have a CTA preceding the BAE (10% CT without cohort versus 4.5% CTA cohort). IV contrast is also well established as an agent that significantly improves the visualization of mediastinal structures. As discussed above, IV contrast shows an added benefit to preprocedural embolization planning. Therefore, CT chest without IV contrast is only warranted in the diagnosis of massive hemoptysis in patients with poor renal function or life-threatening contrast allergy. CT Chest without and with IV Contrast Although early studies used CT chest protocols without IV contrast followed by with IV contrast, there are no data to support any added value of a CT chest without IV contrast prior to administering contrast in the diagnosis of hemoptysis or in preprocedural planning for BAE. CTA Chest CTA has also proven to be beneficial in detecting bronchial and nonbronchial arteries in preprocedural planning. Remy-Jardin et al [34] documented the utility of CTA for BAE preprocedural planning, demonstrating an 86% concordance rate between the 58 abnormal arteries identified on CTA compared with the gold standard of conventional arteriography. Hartmann et al [35] retrospectively reviewed 251 patients (with varying severity of hemoptysis) who were imaged by CTA. Of these 251 patients, 214 had CTAs that were of diagnostic quality without confounding central mediastinal pathology.

Hemoptysis. With the advancement of technology, the vast majority of CT examinations can be reformatted to the resolution of the previously ordered HRCT, and there is rarely an added benefit of HRCT to a routine CT. Khalil et al [33] subsequently published a study retrospectively evaluating patient outcomes comparing a cohort of patients who had a CT without IV contrast with a cohort of patients who underwent CTA. There was a statistically significant difference in the number of emergent surgical resections following embolization in patients who did not have a CTA preceding the BAE (10% CT without cohort versus 4.5% CTA cohort). IV contrast is also well established as an agent that significantly improves the visualization of mediastinal structures. As discussed above, IV contrast shows an added benefit to preprocedural embolization planning. Therefore, CT chest without IV contrast is only warranted in the diagnosis of massive hemoptysis in patients with poor renal function or life-threatening contrast allergy. CT Chest without and with IV Contrast Although early studies used CT chest protocols without IV contrast followed by with IV contrast, there are no data to support any added value of a CT chest without IV contrast prior to administering contrast in the diagnosis of hemoptysis or in preprocedural planning for BAE. CTA Chest CTA has also proven to be beneficial in detecting bronchial and nonbronchial arteries in preprocedural planning. Remy-Jardin et al [34] documented the utility of CTA for BAE preprocedural planning, demonstrating an 86% concordance rate between the 58 abnormal arteries identified on CTA compared with the gold standard of conventional arteriography. Hartmann et al [35] retrospectively reviewed 251 patients (with varying severity of hemoptysis) who were imaged by CTA. Of these 251 patients, 214 had CTAs that were of diagnostic quality without confounding central mediastinal pathology.

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Hemoptysis

The purpose of this study was to analyze the frequency of aberrant and ectopic locations of bleeding arteries. Of the 24 patients who required BAE, 36% had aberrant bronchial origins, and the authors asserted that CTA information guided successful and rapid catheterization in 22 patients and precluded repeated arteriograms. CTA information changed treatment strategy in 2 of the 24 patients with aberrant arteries, resulting in initial treatment with surgical ligation rather than BAE because of an anticipated high risk of Hemoptysis embolization based on vascular location. Mori et al [36] were also early in advocating CTA for preprocedural planning, identifying bronchial artery diameter as an important diagnostic clue on CTA in determining the bleeding artery requiring embolization. Jiang et al [37] reported results from 818 patients obtaining a CTA for preprocedural BAE planning, which isolated 6 aberrant arteries that would not have been detected by standard angiographic procedures. Lin et al [38] also reported a high concordance rate between CTA and conventional arteriography, reporting that 107 of the 110 arteries embolized (97%) were prospectively identified on CTA. This article noted that CTA was useful in both identifying the number of vessels involved in hemoptysis as well as identifying collateral vessels and shunts that increase the risk of complications during arterial embolization. As discussed in the section above, approximately 10% of massive hemoptysis is due to a pulmonary arterial source, which can be occult on bronchial arteriography. Khalil et al [25] retrospectively reviewed 272 patients, 13 of whom had bleeding from a pulmonary artery origin. Of these 13 patients, 8 were initially and successfully treated with pulmonary artery embolization based on the CTA findings, and 3 more patients were subsequently imaged and successfully treated with pulmonary artery embolization after BAE failed to treat the hemoptysis. This study highlighted CTA guiding embolization therapy.

Hemoptysis. The purpose of this study was to analyze the frequency of aberrant and ectopic locations of bleeding arteries. Of the 24 patients who required BAE, 36% had aberrant bronchial origins, and the authors asserted that CTA information guided successful and rapid catheterization in 22 patients and precluded repeated arteriograms. CTA information changed treatment strategy in 2 of the 24 patients with aberrant arteries, resulting in initial treatment with surgical ligation rather than BAE because of an anticipated high risk of Hemoptysis embolization based on vascular location. Mori et al [36] were also early in advocating CTA for preprocedural planning, identifying bronchial artery diameter as an important diagnostic clue on CTA in determining the bleeding artery requiring embolization. Jiang et al [37] reported results from 818 patients obtaining a CTA for preprocedural BAE planning, which isolated 6 aberrant arteries that would not have been detected by standard angiographic procedures. Lin et al [38] also reported a high concordance rate between CTA and conventional arteriography, reporting that 107 of the 110 arteries embolized (97%) were prospectively identified on CTA. This article noted that CTA was useful in both identifying the number of vessels involved in hemoptysis as well as identifying collateral vessels and shunts that increase the risk of complications during arterial embolization. As discussed in the section above, approximately 10% of massive hemoptysis is due to a pulmonary arterial source, which can be occult on bronchial arteriography. Khalil et al [25] retrospectively reviewed 272 patients, 13 of whom had bleeding from a pulmonary artery origin. Of these 13 patients, 8 were initially and successfully treated with pulmonary artery embolization based on the CTA findings, and 3 more patients were subsequently imaged and successfully treated with pulmonary artery embolization after BAE failed to treat the hemoptysis. This study highlighted CTA guiding embolization therapy.

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acrac_69449_5

Hemoptysis

A study by Shin et al [24] also documented the importance of detecting a pulmonary artery source of hemoptysis prior to embolization. In his study of 286 patients presenting with massive hemoptysis, they used CTA to identify 10 patients for a total of 11 PAPs as the source of the massive hemoptysis by CTA prior to undergoing BAE. Of these 11 PAPs, 6 PAPs detected on CTA could not be detected prospectively on conventional pulmonary arteriography, but CTA guided subselection pulmonary arteriography and resulted in successful embolization of the bleeding artery. The authors reported a pulmonary artery embolization success rate of over 90%. A subsequent study by Shin et al [26] also identified patients presenting with massive hemoptysis due to a pulmonary arterial source. Out of 712 patients with massive hemoptysis, 24 patients demonstrated PAPs on their preprocedural CTA examination. Fifteen of these PAPs identified on CTA were also visualized on pulmonary arteriography, all of which were successfully embolized. The remaining 9 PAPs identified on CTA were not detectable on conventional pulmonary arteriography and were subsequently treated with bronchial and systemic nonbronchial embolization, resulting in a 33% rate of hemoptysis cessation. Persistently symptomatic PAPs were subsequently treated by percutaneous or surgical interventions based on CTA findings. There are no recent data comparing the diagnostic advantages between routine CT with IV contrast with CTA. However, CTA may offer a slight advantage over routine CT with IV contrast when the intention is to treat massive hemoptysis with BAE because CTA typically provides slightly better opacification of vessels, possibly improving detection of abnormal arteries potentially causing hemoptysis. At present, the vast majority of publications reporting BAE outcomes obtain CTA chest CTs prior to BAE for preprocedural planning.

Hemoptysis. A study by Shin et al [24] also documented the importance of detecting a pulmonary artery source of hemoptysis prior to embolization. In his study of 286 patients presenting with massive hemoptysis, they used CTA to identify 10 patients for a total of 11 PAPs as the source of the massive hemoptysis by CTA prior to undergoing BAE. Of these 11 PAPs, 6 PAPs detected on CTA could not be detected prospectively on conventional pulmonary arteriography, but CTA guided subselection pulmonary arteriography and resulted in successful embolization of the bleeding artery. The authors reported a pulmonary artery embolization success rate of over 90%. A subsequent study by Shin et al [26] also identified patients presenting with massive hemoptysis due to a pulmonary arterial source. Out of 712 patients with massive hemoptysis, 24 patients demonstrated PAPs on their preprocedural CTA examination. Fifteen of these PAPs identified on CTA were also visualized on pulmonary arteriography, all of which were successfully embolized. The remaining 9 PAPs identified on CTA were not detectable on conventional pulmonary arteriography and were subsequently treated with bronchial and systemic nonbronchial embolization, resulting in a 33% rate of hemoptysis cessation. Persistently symptomatic PAPs were subsequently treated by percutaneous or surgical interventions based on CTA findings. There are no recent data comparing the diagnostic advantages between routine CT with IV contrast with CTA. However, CTA may offer a slight advantage over routine CT with IV contrast when the intention is to treat massive hemoptysis with BAE because CTA typically provides slightly better opacification of vessels, possibly improving detection of abnormal arteries potentially causing hemoptysis. At present, the vast majority of publications reporting BAE outcomes obtain CTA chest CTs prior to BAE for preprocedural planning.

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acrac_69449_6

Hemoptysis

Radiography Chest Chest radiography has long been established as the initial imaging examination of choice given its portability, rapid acquisition, and interpretation time. Fartoukh et al [12], in a large retrospective study of 1,087 patients, correlated morbidity and mortality to findings on chest radiographs. However, there is discrepancy in the literature regarding the usefulness of radiographs in determining the etiology of hemoptysis. In a study of 70 patients undergoing bronchial artery embolization for massive hemoptysis, causative radiologic abnormalities were seen in 86% of the chest radiographs [39]. This was similar to an earlier study showing 82% of chest radiographs could detect the side and predict the cause of bleeding [40]. However, in a comparable study of 80 patients with massive hemoptysis, chest radiographs demonstrated the cause of bleeding in only 35% of cases, most of whom had tuberculosis or malignancy [28]. Although radiography can be useful in directing treatment to the correct site of bleeding, a study of 20 patients undergoing BAE for massive hemoptysis showed that radiography localized the site of hemoptysis in only 35% of patients [41]. Similar findings were reported in a larger study of 348 patients, which included both massive and moderate recurrent hemoptysis patients [17]. Chest radiographs were performed in all patients and were abnormal in 313 patients (90%). However, these radiographs were suggestive of the etiology of hemoptysis in only 90 patients (26%). These findings indicate that additional imaging in conjunction with chest radiograph is warranted in massive hemoptysis. Hemoptysis 44]. However, these prior variables excluded a significant portion of patients with nonmassive hemoptysis. In addition, imaging recommendations did not significantly differ between the two prior nonmassive hemoptysis variables. For these reasons, these risk factors have been removed, and there is a single nonmassive variable.

Hemoptysis. Radiography Chest Chest radiography has long been established as the initial imaging examination of choice given its portability, rapid acquisition, and interpretation time. Fartoukh et al [12], in a large retrospective study of 1,087 patients, correlated morbidity and mortality to findings on chest radiographs. However, there is discrepancy in the literature regarding the usefulness of radiographs in determining the etiology of hemoptysis. In a study of 70 patients undergoing bronchial artery embolization for massive hemoptysis, causative radiologic abnormalities were seen in 86% of the chest radiographs [39]. This was similar to an earlier study showing 82% of chest radiographs could detect the side and predict the cause of bleeding [40]. However, in a comparable study of 80 patients with massive hemoptysis, chest radiographs demonstrated the cause of bleeding in only 35% of cases, most of whom had tuberculosis or malignancy [28]. Although radiography can be useful in directing treatment to the correct site of bleeding, a study of 20 patients undergoing BAE for massive hemoptysis showed that radiography localized the site of hemoptysis in only 35% of patients [41]. Similar findings were reported in a larger study of 348 patients, which included both massive and moderate recurrent hemoptysis patients [17]. Chest radiographs were performed in all patients and were abnormal in 313 patients (90%). However, these radiographs were suggestive of the etiology of hemoptysis in only 90 patients (26%). These findings indicate that additional imaging in conjunction with chest radiograph is warranted in massive hemoptysis. Hemoptysis 44]. However, these prior variables excluded a significant portion of patients with nonmassive hemoptysis. In addition, imaging recommendations did not significantly differ between the two prior nonmassive hemoptysis variables. For these reasons, these risk factors have been removed, and there is a single nonmassive variable.

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acrac_69449_7

Hemoptysis

Additional recent studies reporting BAE as a viable therapeutic option for nonmassive hemoptysis includes Dave et al [46], who reported BAE outcomes on 58 patients. In this study, 17% of the population presented with nonmassive hemoptysis, and the top two causes of hemoptysis were bronchiectasis and malignancy. The success rates proved to be similar between patients presenting with nonmassive versus massive hemoptysis. This study asserted that nonmassive hemoptysis might be the harbinger of future episodes of massive hemoptysis, especially in patients with underlying lung disease. These results justify BAE as a treatment of nonmassive hemoptysis. Woo et al [18] reported BAE outcomes on 406 patients, 30% of whom presented with nonmassive hemoptysis. This study also demonstrated similar success rates between patients with nonmassive versus massive hemoptysis. Shin et al [19] reported BAE outcomes on 163 patients, including 41% presenting with nonmassive hemoptysis; outcomes were not stratified by hemoptysis severity. Bhalla et al [15] reported similar post-BAE outcomes between patients presenting with nonmassive versus massive hemoptysis. Ishikawa et al [47] published the largest study on outcomes for nonmassive hemoptysis. Elective BAE was performed on 489 noncancer patients from Japan with varying degrees of nonemergent hemoptysis. They reported immediate bleeding cessation in 93% of patients, with 87% and 58% of patients remaining free of hemoptysis at 1 and 3 years, respectively. The most common causes of hemoptysis in this study were bronchiectasis (34%) and nontuberculous mycobacterium (24%). Cryptogenic nonmassive hemoptysis has demonstrated a very high immediate and long-term success rate following BAE. In a retrospective study [48] reviewing 319 patients, 35 patients were identified as having cryptogenic hemoptysis, 23 of whom reported nonmassive hemoptysis.

Hemoptysis. Additional recent studies reporting BAE as a viable therapeutic option for nonmassive hemoptysis includes Dave et al [46], who reported BAE outcomes on 58 patients. In this study, 17% of the population presented with nonmassive hemoptysis, and the top two causes of hemoptysis were bronchiectasis and malignancy. The success rates proved to be similar between patients presenting with nonmassive versus massive hemoptysis. This study asserted that nonmassive hemoptysis might be the harbinger of future episodes of massive hemoptysis, especially in patients with underlying lung disease. These results justify BAE as a treatment of nonmassive hemoptysis. Woo et al [18] reported BAE outcomes on 406 patients, 30% of whom presented with nonmassive hemoptysis. This study also demonstrated similar success rates between patients with nonmassive versus massive hemoptysis. Shin et al [19] reported BAE outcomes on 163 patients, including 41% presenting with nonmassive hemoptysis; outcomes were not stratified by hemoptysis severity. Bhalla et al [15] reported similar post-BAE outcomes between patients presenting with nonmassive versus massive hemoptysis. Ishikawa et al [47] published the largest study on outcomes for nonmassive hemoptysis. Elective BAE was performed on 489 noncancer patients from Japan with varying degrees of nonemergent hemoptysis. They reported immediate bleeding cessation in 93% of patients, with 87% and 58% of patients remaining free of hemoptysis at 1 and 3 years, respectively. The most common causes of hemoptysis in this study were bronchiectasis (34%) and nontuberculous mycobacterium (24%). Cryptogenic nonmassive hemoptysis has demonstrated a very high immediate and long-term success rate following BAE. In a retrospective study [48] reviewing 319 patients, 35 patients were identified as having cryptogenic hemoptysis, 23 of whom reported nonmassive hemoptysis.

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Hemoptysis

Thirty-three of the 35 patients with cryptogenic hemoptysis were successfully treated with BAE, and 97% of these patients remained free of hemoptysis at 20 months. The authors reported that there was no correlation between severity of hemoptysis and the diameter of the embolized bronchial artery. These results were not compared to the patients with a known cause of hemoptysis. CT Chest with IV Contrast As with massive hemoptysis, CT with IV contrast is the primary modality to determine hemoptysis etiology. Thirumaran et al [44], in an early study establishing CT as a diagnostic tool for nonmassive hemoptysis, retrospectively studied 270 patients with hemoptysis and a normal chest radiograph, with 94% reporting mild hemoptysis, and commonly with repeated episodes. Although the most common cause of hemoptysis was acute bronchitis (63%), the second most common cause was a respiratory tract neoplasm, the majority of which was a lung primary malignancy (n = 22/270). Lee et al [49] reported performing CT examinations on all 221 patients evaluated for hemoptysis, 48% with nonmassive hemoptysis and 52% with massive hemoptysis. Interestingly, both cohorts had similar etiologies, with bronchiectasis followed by active tuberculosis as the leading causes for hemoptysis, and CT proved to be the superior diagnostic imaging modality over bronchoscopy and arteriography for identifying the cause of hemoptysis. CT with IV contrast is now the established imaging modality to determine the etiology of nonmassive hemoptysis, and therefore, there are no recent publications comparing its efficacy to other imaging modalities. CT Chest without IV Contrast As discussed in Variant 1, CT chest without IV contrast is only warranted in the diagnosis of hemoptysis in patients with poor renal function or life-threatening contrast allergy. The limited number of studies reviewing the utility of

Hemoptysis. Thirty-three of the 35 patients with cryptogenic hemoptysis were successfully treated with BAE, and 97% of these patients remained free of hemoptysis at 20 months. The authors reported that there was no correlation between severity of hemoptysis and the diameter of the embolized bronchial artery. These results were not compared to the patients with a known cause of hemoptysis. CT Chest with IV Contrast As with massive hemoptysis, CT with IV contrast is the primary modality to determine hemoptysis etiology. Thirumaran et al [44], in an early study establishing CT as a diagnostic tool for nonmassive hemoptysis, retrospectively studied 270 patients with hemoptysis and a normal chest radiograph, with 94% reporting mild hemoptysis, and commonly with repeated episodes. Although the most common cause of hemoptysis was acute bronchitis (63%), the second most common cause was a respiratory tract neoplasm, the majority of which was a lung primary malignancy (n = 22/270). Lee et al [49] reported performing CT examinations on all 221 patients evaluated for hemoptysis, 48% with nonmassive hemoptysis and 52% with massive hemoptysis. Interestingly, both cohorts had similar etiologies, with bronchiectasis followed by active tuberculosis as the leading causes for hemoptysis, and CT proved to be the superior diagnostic imaging modality over bronchoscopy and arteriography for identifying the cause of hemoptysis. CT with IV contrast is now the established imaging modality to determine the etiology of nonmassive hemoptysis, and therefore, there are no recent publications comparing its efficacy to other imaging modalities. CT Chest without IV Contrast As discussed in Variant 1, CT chest without IV contrast is only warranted in the diagnosis of hemoptysis in patients with poor renal function or life-threatening contrast allergy. The limited number of studies reviewing the utility of

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Hemoptysis

Hemoptysis CT chest without IV contrast for the evaluation of hemoptysis did not differentiate between massive versus nonmassive quantities of hemoptysis. CT Chest without and with IV Contrast Although very early publications studying the utility of CT in patients presenting with nonmassive hemoptysis performed chest protocols including acquisitions both without IV contrast followed by acquisitions with IV contrast, there are no data to support that there is any added value of CT chest without IV contrast prior to the administration of IV contrast in the diagnosis of nonmassive hemoptysis or in the preprocedural planning of BAE. CTA Chest There are no recent studies comparing the benefits of a routine chest CT with IV contrast to CTA in patients with nonmassive hemoptysis. As previously discussed, preprocedural CTA or routine CT with IV contrast has become the standard of care for arterial planning of BAE. In a recent study reporting the outcomes of BAE in patients with primarily nonmassive hemoptysis, all 489 noncancer patients underwent a CTA prior to embolization [47]. The authors noted that conventional aortography previously used to detect origins of the bleeding bronchial arteries was effectively replaced by arterial mapping information provided by CTA. Radiography Chest Chest radiographs continue to be a reasonable initial imaging choice in patients with nonmassive hemoptysis, especially when used to confirm a clinical diagnosis for benign disease such as acute bronchitis or pneumonia. There are no recent studies comparing the utility of chest radiographs with other imaging modalities. Variant 3: Recurrent hemoptysis. Initial imaging. Recurrent hemoptysis is a new variant for this update. It is defined as repeated episodes of hemoptysis following initial treatment with either medical therapy or BAE. Typically, the etiology of recurrent hemoptysis is known and usually not life threatening, although there is a wide range of hemoptysis severity.

Hemoptysis. Hemoptysis CT chest without IV contrast for the evaluation of hemoptysis did not differentiate between massive versus nonmassive quantities of hemoptysis. CT Chest without and with IV Contrast Although very early publications studying the utility of CT in patients presenting with nonmassive hemoptysis performed chest protocols including acquisitions both without IV contrast followed by acquisitions with IV contrast, there are no data to support that there is any added value of CT chest without IV contrast prior to the administration of IV contrast in the diagnosis of nonmassive hemoptysis or in the preprocedural planning of BAE. CTA Chest There are no recent studies comparing the benefits of a routine chest CT with IV contrast to CTA in patients with nonmassive hemoptysis. As previously discussed, preprocedural CTA or routine CT with IV contrast has become the standard of care for arterial planning of BAE. In a recent study reporting the outcomes of BAE in patients with primarily nonmassive hemoptysis, all 489 noncancer patients underwent a CTA prior to embolization [47]. The authors noted that conventional aortography previously used to detect origins of the bleeding bronchial arteries was effectively replaced by arterial mapping information provided by CTA. Radiography Chest Chest radiographs continue to be a reasonable initial imaging choice in patients with nonmassive hemoptysis, especially when used to confirm a clinical diagnosis for benign disease such as acute bronchitis or pneumonia. There are no recent studies comparing the utility of chest radiographs with other imaging modalities. Variant 3: Recurrent hemoptysis. Initial imaging. Recurrent hemoptysis is a new variant for this update. It is defined as repeated episodes of hemoptysis following initial treatment with either medical therapy or BAE. Typically, the etiology of recurrent hemoptysis is known and usually not life threatening, although there is a wide range of hemoptysis severity.

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Hemoptysis

Recent literature shows a trend of more commonly treating patients with nonmassive recurrent hemoptysis with interventional or surgical procedures rather than conservative therapies compared with patients with an initial presentation of nonmassive hemoptysis. Therefore, imaging recommendations differ between patients initially presenting with nonmassive hemoptysis and patients presenting with recurrent nonmassive hemoptysis. Hemoptysis outcomes were due to sequelae from BAE or sequelae from recurrent hemoptysis. Of the handful of studies documenting lack of clinically significant change following BAE, Tom et al [4] specifically studied long-term clinical parameters of patients prior to and following BAE. Of the 69 patients with hemoptysis initially treated with BAE, 17 patients had at least 5 years of clinical data before and 5 years of clinical data after the initial BAE. The authors identified that pulmonary function parameters declined at the same rate prior to the initial BAE as they had following BAE. CT Chest with IV Contrast Patients with recurrent hemoptysis typically have a known cause. Bronchiectasis due to repeated or indolent infection is the most common cause for recurrent hemoptysis in most large studies. In patients with cystic fibrosis, for example, recurrent hemoptysis may be an indicator of acute infection [60], and CT may not be indicated. There are limited data evaluating the utility of CT chest with IV contrast in the setting of a known cause of hemoptysis. CT Chest without IV Contrast There is no relevant literature supporting the use of CT chest without IV contrast in the assessment of recurrent hemoptysis. CT Chest without and with IV Contrast There is no relevant literature supporting the use of CT chest without IV contrast prior to a CT performed with IV contrast in patients with recurrent hemoptysis. CTA Chest There are no recent data comparing the diagnostic advantages between routine CT with IV contrast with CTA in patients with recurrent hemoptysis.

Hemoptysis. Recent literature shows a trend of more commonly treating patients with nonmassive recurrent hemoptysis with interventional or surgical procedures rather than conservative therapies compared with patients with an initial presentation of nonmassive hemoptysis. Therefore, imaging recommendations differ between patients initially presenting with nonmassive hemoptysis and patients presenting with recurrent nonmassive hemoptysis. Hemoptysis outcomes were due to sequelae from BAE or sequelae from recurrent hemoptysis. Of the handful of studies documenting lack of clinically significant change following BAE, Tom et al [4] specifically studied long-term clinical parameters of patients prior to and following BAE. Of the 69 patients with hemoptysis initially treated with BAE, 17 patients had at least 5 years of clinical data before and 5 years of clinical data after the initial BAE. The authors identified that pulmonary function parameters declined at the same rate prior to the initial BAE as they had following BAE. CT Chest with IV Contrast Patients with recurrent hemoptysis typically have a known cause. Bronchiectasis due to repeated or indolent infection is the most common cause for recurrent hemoptysis in most large studies. In patients with cystic fibrosis, for example, recurrent hemoptysis may be an indicator of acute infection [60], and CT may not be indicated. There are limited data evaluating the utility of CT chest with IV contrast in the setting of a known cause of hemoptysis. CT Chest without IV Contrast There is no relevant literature supporting the use of CT chest without IV contrast in the assessment of recurrent hemoptysis. CT Chest without and with IV Contrast There is no relevant literature supporting the use of CT chest without IV contrast prior to a CT performed with IV contrast in patients with recurrent hemoptysis. CTA Chest There are no recent data comparing the diagnostic advantages between routine CT with IV contrast with CTA in patients with recurrent hemoptysis.

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acrac_3158182_0

Workup of Noncerebral Systemic Arterial Embolic Source

Introduction/Background Noncerebral systemic arterial embolism is an important cause of patient morbidity and mortality [1]. Arterial emboli can originate from a variety of cardiac and noncardiac sources. Cardiac sources include thrombus within the left atrium and left ventricle, valvular disease such as endocarditis, and cardiac neoplasms. Noncardiac sources of arterial embolism include thrombus and atherosclerosis within the aorta and peripheral arteries. Intracardiac thrombus has been thoroughly described in the cardiology and neurology literature with several factors that predispose its formation and the potential for arterial embolization. For example, atrial fibrillation has been shown to be a significant risk factor for atrial thrombogenesis [2,3]. Complex left atrial appendage morphology also confers increased likelihood of thrombus development [4]. Myocardial infarction often results in focal hypokinesis or akinesis of the left ventricular myocardium, which predisposes to thrombus formation [5,6]. Aortic and mitral valve endocarditis as well as valvular neoplasms are other potential sources for arterial embolism detectable with imaging [7,8]. Aortic thrombi tend to be associated with aortic pathology including dissection, aneurysm, or ulcerative lesions [9,10]. Thrombus formation can also occur in the aorta secondary to hypercoagulable states such as malignancy, trauma, postoperative states, hormonal therapy, and inherited hypercoagulable disorders [1,11,12]. When a cardiac or noncardiac embolic source dislodges, the resulting embolus can occlude a variety of peripheral and visceral arteries causing ischemia [1,9,11,12]. Characteristic locations for noncerebral arterial occlusion include the upper extremities, abdominal viscera, and lower extremities [1,9,11]. Ischemia in these regions can progress to tissue infarction resulting in limb amputation, bowel resection, or nephrectomy.

Workup of Noncerebral Systemic Arterial Embolic Source. Introduction/Background Noncerebral systemic arterial embolism is an important cause of patient morbidity and mortality [1]. Arterial emboli can originate from a variety of cardiac and noncardiac sources. Cardiac sources include thrombus within the left atrium and left ventricle, valvular disease such as endocarditis, and cardiac neoplasms. Noncardiac sources of arterial embolism include thrombus and atherosclerosis within the aorta and peripheral arteries. Intracardiac thrombus has been thoroughly described in the cardiology and neurology literature with several factors that predispose its formation and the potential for arterial embolization. For example, atrial fibrillation has been shown to be a significant risk factor for atrial thrombogenesis [2,3]. Complex left atrial appendage morphology also confers increased likelihood of thrombus development [4]. Myocardial infarction often results in focal hypokinesis or akinesis of the left ventricular myocardium, which predisposes to thrombus formation [5,6]. Aortic and mitral valve endocarditis as well as valvular neoplasms are other potential sources for arterial embolism detectable with imaging [7,8]. Aortic thrombi tend to be associated with aortic pathology including dissection, aneurysm, or ulcerative lesions [9,10]. Thrombus formation can also occur in the aorta secondary to hypercoagulable states such as malignancy, trauma, postoperative states, hormonal therapy, and inherited hypercoagulable disorders [1,11,12]. When a cardiac or noncardiac embolic source dislodges, the resulting embolus can occlude a variety of peripheral and visceral arteries causing ischemia [1,9,11,12]. Characteristic locations for noncerebral arterial occlusion include the upper extremities, abdominal viscera, and lower extremities [1,9,11]. Ischemia in these regions can progress to tissue infarction resulting in limb amputation, bowel resection, or nephrectomy.

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Determining the source of arterial embolism is essential in order to direct treatment decisions. Treatment options vary and include anti-coagulation, endovascular or surgical embolectomy, and peripheral arterial angioplasty with or without stenting to maintain long- term vascular patency [1,9,11-14]. The variants in this document assume that the diagnosis of an arterial occlusion has already been established by other means. For example, in the setting of an acute onset cold painful leg, the use of lower extremity arteriography, CT angiography (CTA), or MR angiography (MRA) could be employed to demonstrate arterial occlusion. This document specifically pertains to the workup of a suspected embolic etiology of the already known arterial occlusion. aResearch Author, University of Texas Southwestern Medical Center, Dallas, Texas. bUT Southwestern Medical Center, Dallas, Texas. cNaval Medical Center Portsmouth, Portsmouth, Virginia. dPanel Chair, Emory Healthcare, Atlanta, Georgia. ePanel Chair, Duke University Medical Center, Durham, North Carolina. fPanel Vice-Chair, University of Michigan, Ann Arbor, Michigan. gPanel Vice-Chair, Massachusetts General Hospital, Boston, Massachusetts. hUniversity of Michigan, Ann Arbor, Michigan. iAllegheny Health Network, Pittsburgh, Pennsylvania. jUniversity of North Carolina School of Medicine, Chapel Hill, North Carolina. kSentara Norfolk General Hospital/Eastern Virginia Medical School, Norfolk, Virginia; American College of Emergency Physicians. lVA Palo Alto Health Care System, Palo Alto, California and Stanford University, Stanford, California. mThe University of Texas MD Anderson Cancer Center, Houston, Texas; Commission on Nuclear Medicine and Molecular Imaging. nDuke University Medical Center, Durham, North Carolina, Primary care physician. oMayo Clinic, Rochester, Minnesota; Society of Cardiovascular Computed Tomography. pSpecialty Chair, UT Southwestern Medical Center, Dallas, Texas.

Workup of Noncerebral Systemic Arterial Embolic Source. Determining the source of arterial embolism is essential in order to direct treatment decisions. Treatment options vary and include anti-coagulation, endovascular or surgical embolectomy, and peripheral arterial angioplasty with or without stenting to maintain long- term vascular patency [1,9,11-14]. The variants in this document assume that the diagnosis of an arterial occlusion has already been established by other means. For example, in the setting of an acute onset cold painful leg, the use of lower extremity arteriography, CT angiography (CTA), or MR angiography (MRA) could be employed to demonstrate arterial occlusion. This document specifically pertains to the workup of a suspected embolic etiology of the already known arterial occlusion. aResearch Author, University of Texas Southwestern Medical Center, Dallas, Texas. bUT Southwestern Medical Center, Dallas, Texas. cNaval Medical Center Portsmouth, Portsmouth, Virginia. dPanel Chair, Emory Healthcare, Atlanta, Georgia. ePanel Chair, Duke University Medical Center, Durham, North Carolina. fPanel Vice-Chair, University of Michigan, Ann Arbor, Michigan. gPanel Vice-Chair, Massachusetts General Hospital, Boston, Massachusetts. hUniversity of Michigan, Ann Arbor, Michigan. iAllegheny Health Network, Pittsburgh, Pennsylvania. jUniversity of North Carolina School of Medicine, Chapel Hill, North Carolina. kSentara Norfolk General Hospital/Eastern Virginia Medical School, Norfolk, Virginia; American College of Emergency Physicians. lVA Palo Alto Health Care System, Palo Alto, California and Stanford University, Stanford, California. mThe University of Texas MD Anderson Cancer Center, Houston, Texas; Commission on Nuclear Medicine and Molecular Imaging. nDuke University Medical Center, Durham, North Carolina, Primary care physician. oMayo Clinic, Rochester, Minnesota; Society of Cardiovascular Computed Tomography. pSpecialty Chair, UT Southwestern Medical Center, Dallas, Texas.

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qSpecialty Chair, Emory University Hospital, 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. Reprint requests to: [email protected] 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. OR Discussion of Procedures by Variant Variant 1: Known upper extremity arterial occlusion. Suspected embolic etiology. Next imaging study to determine source. The variant assumes that an upper extremity arterial occlusion has already been established. Typically, this diagnosis is made by CTA, arteriography, or MRA, although the clinical examination or another imaging study could also be used. Aortography Chest Conventional catheter aortography has largely been replaced by noninvasive imaging modalities such as CTA and MRA given their high sensitivity/specificity for detecting aortic pathologies such as mural thrombus [16,17]. Aortography is typically used as an alternative diagnostic strategy following initial noninvasive imaging and when therapeutic interventions are being considered [11,17]. CT Heart Function and Morphology With IV Contrast The primary role of cardiac CT in the initial evaluation of upper extremity arterial embolic occlusion is in the workup of cardiac thrombus as a source. Multiple studies have established high rates of atrial thrombus detection by cardiac CT compared to transesophageal echocardiography (TEE) [18-27].

Workup of Noncerebral Systemic Arterial Embolic Source. qSpecialty Chair, Emory University Hospital, 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. Reprint requests to: [email protected] 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. OR Discussion of Procedures by Variant Variant 1: Known upper extremity arterial occlusion. Suspected embolic etiology. Next imaging study to determine source. The variant assumes that an upper extremity arterial occlusion has already been established. Typically, this diagnosis is made by CTA, arteriography, or MRA, although the clinical examination or another imaging study could also be used. Aortography Chest Conventional catheter aortography has largely been replaced by noninvasive imaging modalities such as CTA and MRA given their high sensitivity/specificity for detecting aortic pathologies such as mural thrombus [16,17]. Aortography is typically used as an alternative diagnostic strategy following initial noninvasive imaging and when therapeutic interventions are being considered [11,17]. CT Heart Function and Morphology With IV Contrast The primary role of cardiac CT in the initial evaluation of upper extremity arterial embolic occlusion is in the workup of cardiac thrombus as a source. Multiple studies have established high rates of atrial thrombus detection by cardiac CT compared to transesophageal echocardiography (TEE) [18-27].

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Meta-analyses have found sensitivities of 96% to 99% and specificities of 92% to 94% for detection of left atrial or left atrial appendage thrombus with cardiac CT compared to a TEE reference standard [28-30]. When compared with intraoperative findings, cardiac CT was 100% sensitive and 85% specific for finding left atrial thrombus [31]. Complex left atrial appendage morphologies which predispose to thrombus formation can also be characterized by cardiac CT [32-34]. Additionally, cardiac CT can differentiate left ventricular thrombus from the myocardial wall with 1 study demonstrating a sensitivity, specificity, and positive and negative predictive values of 94%, 97%, 94%, and 97%, respectively [35]. Studies have also demonstrated cardiac CT to have comparable accuracy to TEE for identification of vegetations in the setting of infective endocarditis, another potential source of arterial embolism [36-38]. Cardiac CT can identify cardiac neoplasms, both benign and malignant, which have the potential to shed and embolize to distal arterial beds [39,40]. CTA Chest With IV Contrast Multidetector chest CTA with intravenous (IV) contrast can be used to evaluate for at-risk atherosclerotic plaque or the presence of thrombus in the thoracic aorta. CTA is useful in the assessment of the size, extent, and location of an embolic source in the aorta, which can aid in management decisions [13,41]. A number of small studies have used chest CTA to detect aortic mural thrombus that was suspected of embolization [1,12-14,42]. Specific data on the sensitivity and specificity of this imaging modality are lacking. MRA Chest Without IV Contrast Chest MRA without IV contrast is an imaging study, which can detect the presence of thrombus in the thoracic aorta. One small study found this examination to have a higher detection rate for aortic thrombus when compared with contrast-enhanced MRA, although the difference was not statistically significant [44].

Workup of Noncerebral Systemic Arterial Embolic Source. Meta-analyses have found sensitivities of 96% to 99% and specificities of 92% to 94% for detection of left atrial or left atrial appendage thrombus with cardiac CT compared to a TEE reference standard [28-30]. When compared with intraoperative findings, cardiac CT was 100% sensitive and 85% specific for finding left atrial thrombus [31]. Complex left atrial appendage morphologies which predispose to thrombus formation can also be characterized by cardiac CT [32-34]. Additionally, cardiac CT can differentiate left ventricular thrombus from the myocardial wall with 1 study demonstrating a sensitivity, specificity, and positive and negative predictive values of 94%, 97%, 94%, and 97%, respectively [35]. Studies have also demonstrated cardiac CT to have comparable accuracy to TEE for identification of vegetations in the setting of infective endocarditis, another potential source of arterial embolism [36-38]. Cardiac CT can identify cardiac neoplasms, both benign and malignant, which have the potential to shed and embolize to distal arterial beds [39,40]. CTA Chest With IV Contrast Multidetector chest CTA with intravenous (IV) contrast can be used to evaluate for at-risk atherosclerotic plaque or the presence of thrombus in the thoracic aorta. CTA is useful in the assessment of the size, extent, and location of an embolic source in the aorta, which can aid in management decisions [13,41]. A number of small studies have used chest CTA to detect aortic mural thrombus that was suspected of embolization [1,12-14,42]. Specific data on the sensitivity and specificity of this imaging modality are lacking. MRA Chest Without IV Contrast Chest MRA without IV contrast is an imaging study, which can detect the presence of thrombus in the thoracic aorta. One small study found this examination to have a higher detection rate for aortic thrombus when compared with contrast-enhanced MRA, although the difference was not statistically significant [44].

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In another study, sensitivity, specificity, and diagnostic accuracy of unenhanced steady-state free precession MRA were 100% for the detection of thoracic aorta pathology compared to a contrast-enhanced MRA reference standard; however, this analysis only included 1 case of mural thrombus [43]. Data comparing MRA of the chest to other imaging modalities are lacking. MRI Heart Function and Morphology Without and With IV Contrast Cardiac MR is a noninvasive imaging study that can detect intracardiac thrombus as well as valvular and neoplastic pathologies. A meta-analysis of 7 studies showed that delayed contrast-enhanced cardiac MR had a pooled sensitivity of 100% and a specificity of 99% for detecting left atrial and left atrial appendage thrombus in patients with atrial fibrillation [45]. In another meta-analysis, there was no significant difference in sensitivity and specificity between cardiac CT and cardiac MR in the detection of left atrial appendage thrombus [29]. Contrast-enhanced cardiac MR had a sensitivity of 88% and a specificity of 99% compared to surgical or pathological confirmation of left ventricular thrombus [46]. Cardiac MR is also an accurate imaging modality for the evaluation of valvular disease, including aortic and mitral valve vegetations, which can dislodge and result in arterial embolism [37,47]. Additionally, cardiac MR offers detailed soft tissue characterization for the analysis of benign and malignant intracardiac neoplasms [39,48]. MRI Heart Function and Morphology Without IV Contrast Cardiac MR without contrast provides a detailed anatomic evaluation of the heart chambers. In the workup of embolic sources, the primary role of cardiac MR is in the identification of intracardiac thrombus. A meta-analysis of 7 studies showed that cine cardiac MR had a pooled sensitivity of 91% and a specificity of 93% for detecting left atrial and left atrial appendage thrombus in patients with atrial fibrillation [45].

Workup of Noncerebral Systemic Arterial Embolic Source. In another study, sensitivity, specificity, and diagnostic accuracy of unenhanced steady-state free precession MRA were 100% for the detection of thoracic aorta pathology compared to a contrast-enhanced MRA reference standard; however, this analysis only included 1 case of mural thrombus [43]. Data comparing MRA of the chest to other imaging modalities are lacking. MRI Heart Function and Morphology Without and With IV Contrast Cardiac MR is a noninvasive imaging study that can detect intracardiac thrombus as well as valvular and neoplastic pathologies. A meta-analysis of 7 studies showed that delayed contrast-enhanced cardiac MR had a pooled sensitivity of 100% and a specificity of 99% for detecting left atrial and left atrial appendage thrombus in patients with atrial fibrillation [45]. In another meta-analysis, there was no significant difference in sensitivity and specificity between cardiac CT and cardiac MR in the detection of left atrial appendage thrombus [29]. Contrast-enhanced cardiac MR had a sensitivity of 88% and a specificity of 99% compared to surgical or pathological confirmation of left ventricular thrombus [46]. Cardiac MR is also an accurate imaging modality for the evaluation of valvular disease, including aortic and mitral valve vegetations, which can dislodge and result in arterial embolism [37,47]. Additionally, cardiac MR offers detailed soft tissue characterization for the analysis of benign and malignant intracardiac neoplasms [39,48]. MRI Heart Function and Morphology Without IV Contrast Cardiac MR without contrast provides a detailed anatomic evaluation of the heart chambers. In the workup of embolic sources, the primary role of cardiac MR is in the identification of intracardiac thrombus. A meta-analysis of 7 studies showed that cine cardiac MR had a pooled sensitivity of 91% and a specificity of 93% for detecting left atrial and left atrial appendage thrombus in patients with atrial fibrillation [45].

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Furthermore, cine cardiac MR had an 82% sensitivity and a 100% specificity in detecting left ventricle thrombus in postmyocardial infarction patients compared with a standard delayed enhancement cardiac MR [49]. Cardiac MR without contrast is also capable of identifying valvular pathology and cardiac neoplasms, although data on its applicability in the setting of systemic arterial embolism are lacking. US Duplex Doppler Abdomen There is no relevant literature to support the use of Doppler ultrasound (US) of the abdomen as an initial imaging modality in the evaluation of the source of known embolic upper extremity arterial occlusion. US Echocardiography Transesophageal TEE is an invasive diagnostic study with the ability to detect cardiac pathology predisposed to embolism. TEE has a sensitivity of 93% to 100% and a specificity of 95% to 99% for detecting left atrial appendage thrombus when compared to intraoperative findings [31,50,51]. Furthermore, TEE can evaluate left ventricular systolic dysfunction, spontaneous echo contrast, slow left atrial appendage peak flow velocities, and complex left atrial appendage morphologies, which are all associated with left atrial thrombus and thromboembolic risk [2,4]. In addition, TEE can detect left ventricular thrombus with 1 study reporting a 40% sensitivity and a 96% specificity for the modality compared to findings at surgery or pathology [46]. Proximal aortic thrombus can also be assessed using TEE, although evaluation is limited by blind spots (distal ascending aorta and proximal aortic arch) owing to air in the trachea [10,13]. Detection of valvular disease and intracardiac neoplasms can also be accomplished with TEE. US Echocardiography Transthoracic Resting Transthoracic echocardiography (TTE) is a noninvasive imaging modality capable of detecting cardiac pathology susceptible to embolism. TTE is inferior to TEE in the assessment of left atrial appendage thrombus because the

Workup of Noncerebral Systemic Arterial Embolic Source. Furthermore, cine cardiac MR had an 82% sensitivity and a 100% specificity in detecting left ventricle thrombus in postmyocardial infarction patients compared with a standard delayed enhancement cardiac MR [49]. Cardiac MR without contrast is also capable of identifying valvular pathology and cardiac neoplasms, although data on its applicability in the setting of systemic arterial embolism are lacking. US Duplex Doppler Abdomen There is no relevant literature to support the use of Doppler ultrasound (US) of the abdomen as an initial imaging modality in the evaluation of the source of known embolic upper extremity arterial occlusion. US Echocardiography Transesophageal TEE is an invasive diagnostic study with the ability to detect cardiac pathology predisposed to embolism. TEE has a sensitivity of 93% to 100% and a specificity of 95% to 99% for detecting left atrial appendage thrombus when compared to intraoperative findings [31,50,51]. Furthermore, TEE can evaluate left ventricular systolic dysfunction, spontaneous echo contrast, slow left atrial appendage peak flow velocities, and complex left atrial appendage morphologies, which are all associated with left atrial thrombus and thromboembolic risk [2,4]. In addition, TEE can detect left ventricular thrombus with 1 study reporting a 40% sensitivity and a 96% specificity for the modality compared to findings at surgery or pathology [46]. Proximal aortic thrombus can also be assessed using TEE, although evaluation is limited by blind spots (distal ascending aorta and proximal aortic arch) owing to air in the trachea [10,13]. Detection of valvular disease and intracardiac neoplasms can also be accomplished with TEE. US Echocardiography Transthoracic Resting Transthoracic echocardiography (TTE) is a noninvasive imaging modality capable of detecting cardiac pathology susceptible to embolism. TTE is inferior to TEE in the assessment of left atrial appendage thrombus because the

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5 Workup of Noncerebral Systemic Arterial Embolic Source transducer is distant from the left atrium when placed on the chest [52]. In 1 study, a cardiac embolic source was detected by TEE in about 40% of patients with normal TTE [53]. In another study, a cardiac embolic source was identified by TTE in 15% of the study group compared with 57% by TEE [54]. Sensitivity and specificity were 23% and 96%, respectively, for the detection of left ventricular thrombus compared to findings at surgery or pathology [46]. In the detection of left ventricle thrombus, contrast-enhanced TTE had a 64% sensitivity and a 99% specificity compared to a delayed enhancement cardiac MR standard [49]. TTE can also be applied for the diagnosis of valvular disease and cardiac neoplasms. There is no evidence to support the use of TTE in the evaluation of aortic thrombus. Aortography Chest and Abdomen Conventional catheter aortography has largely been replaced by noninvasive imaging modalities such as CTA and MRA given their high sensitivity/specificity for detecting aortic pathologies such as mural thrombus [16,17]. Aortography is typically used as an alternative diagnostic strategy following initial noninvasive imaging and when therapeutic interventions are being considered [11,17]. CT Heart Function and Morphology With IV Contrast The primary role of cardiac CT in the initial evaluation of mesenteric or renal arterial embolic occlusion is in the workup of cardiac thrombus as a source. Multiple studies have established high rates of atrial thrombus detection by cardiac CT compared to TEE [18-27]. Meta-analyses have found sensitivities of 96% to 99% and specificities of 92% to 94% for detection of left atrial or left atrial appendage thrombus with cardiac CT compared to a TEE reference standard [28-30]. When compared to intraoperative findings, cardiac CT was 100% sensitive and 85% specific for finding left atrial thrombus [31].

Workup of Noncerebral Systemic Arterial Embolic Source. 5 Workup of Noncerebral Systemic Arterial Embolic Source transducer is distant from the left atrium when placed on the chest [52]. In 1 study, a cardiac embolic source was detected by TEE in about 40% of patients with normal TTE [53]. In another study, a cardiac embolic source was identified by TTE in 15% of the study group compared with 57% by TEE [54]. Sensitivity and specificity were 23% and 96%, respectively, for the detection of left ventricular thrombus compared to findings at surgery or pathology [46]. In the detection of left ventricle thrombus, contrast-enhanced TTE had a 64% sensitivity and a 99% specificity compared to a delayed enhancement cardiac MR standard [49]. TTE can also be applied for the diagnosis of valvular disease and cardiac neoplasms. There is no evidence to support the use of TTE in the evaluation of aortic thrombus. Aortography Chest and Abdomen Conventional catheter aortography has largely been replaced by noninvasive imaging modalities such as CTA and MRA given their high sensitivity/specificity for detecting aortic pathologies such as mural thrombus [16,17]. Aortography is typically used as an alternative diagnostic strategy following initial noninvasive imaging and when therapeutic interventions are being considered [11,17]. CT Heart Function and Morphology With IV Contrast The primary role of cardiac CT in the initial evaluation of mesenteric or renal arterial embolic occlusion is in the workup of cardiac thrombus as a source. Multiple studies have established high rates of atrial thrombus detection by cardiac CT compared to TEE [18-27]. Meta-analyses have found sensitivities of 96% to 99% and specificities of 92% to 94% for detection of left atrial or left atrial appendage thrombus with cardiac CT compared to a TEE reference standard [28-30]. When compared to intraoperative findings, cardiac CT was 100% sensitive and 85% specific for finding left atrial thrombus [31].

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Complex left atrial appendage morphologies that predispose to thrombus formation can also be characterized by cardiac CT [32-34]. Additionally, cardiac CT can differentiate left ventricular thrombus from the myocardial wall, with 1 study demonstrating a sensitivity, specificity, and positive and negative predictive values of 94%, 97%, 94%, and 97%, respectively [35]. Studies have also demonstrated cardiac CT to have comparable accuracy to TEE for identification of vegetations in the setting of infective endocarditis, another potential source of arterial embolism [36-38]. Cardiac CT can identify cardiac neoplasms, both benign and malignant, which have the potential to shed and embolize to distal arterial beds [39,40]. CTA Chest With IV Contrast In some conditions or clinical scenarios, there may be a high suspicion that the embolic source is in the thoracic aorta, and a CTA limited to the chest may be diagnostic. As such, multidetector chest CTA with IV contrast can be used to evaluate for at-risk atherosclerotic plaque or the presence of thrombus in the thoracic aorta. CTA is useful in the assessment of the size, extent, and location of an embolic source in the aorta, which can aid in management decisions [13,41]. A number of small studies have used chest CTA to detect aortic mural thrombus that was suspected of embolization [1,12-14,42]. Specific data on the sensitivity and specificity of this imaging modality are lacking. CTA Chest and Abdomen With IV Contrast Multidetector CTA with IV contrast can be used to evaluate for the presence of at-risk atherosclerotic plaque or thrombus in the aorta in its entirety. CTA is useful in the assessment of the size, extent, and location of an embolic source in the aorta, which can aid in management decisions [13,41]. Aortic intraluminal thrombus is oftentimes associated with aneurysm, particularly in the abdomen, which is readily detected by CTA [56,57].

Workup of Noncerebral Systemic Arterial Embolic Source. Complex left atrial appendage morphologies that predispose to thrombus formation can also be characterized by cardiac CT [32-34]. Additionally, cardiac CT can differentiate left ventricular thrombus from the myocardial wall, with 1 study demonstrating a sensitivity, specificity, and positive and negative predictive values of 94%, 97%, 94%, and 97%, respectively [35]. Studies have also demonstrated cardiac CT to have comparable accuracy to TEE for identification of vegetations in the setting of infective endocarditis, another potential source of arterial embolism [36-38]. Cardiac CT can identify cardiac neoplasms, both benign and malignant, which have the potential to shed and embolize to distal arterial beds [39,40]. CTA Chest With IV Contrast In some conditions or clinical scenarios, there may be a high suspicion that the embolic source is in the thoracic aorta, and a CTA limited to the chest may be diagnostic. As such, multidetector chest CTA with IV contrast can be used to evaluate for at-risk atherosclerotic plaque or the presence of thrombus in the thoracic aorta. CTA is useful in the assessment of the size, extent, and location of an embolic source in the aorta, which can aid in management decisions [13,41]. A number of small studies have used chest CTA to detect aortic mural thrombus that was suspected of embolization [1,12-14,42]. Specific data on the sensitivity and specificity of this imaging modality are lacking. CTA Chest and Abdomen With IV Contrast Multidetector CTA with IV contrast can be used to evaluate for the presence of at-risk atherosclerotic plaque or thrombus in the aorta in its entirety. CTA is useful in the assessment of the size, extent, and location of an embolic source in the aorta, which can aid in management decisions [13,41]. Aortic intraluminal thrombus is oftentimes associated with aneurysm, particularly in the abdomen, which is readily detected by CTA [56,57].

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A number of small studies have used CTA to detect aortic mural thrombus that was suspected of embolization [1,12-14,42]. Specific data on the sensitivity and specificity of this imaging modality are lacking. MRA Chest Without and With IV Contrast In some conditions or clinical scenarios, there may be a high suspicion that the embolic source is in the thoracic aorta and an MRA limited to the chest may be diagnostic. In 1 study, detection of thoracic aorta pathology by contrast-enhanced chest MRA was equivalent in sensitivity, specificity, and diagnostic accuracy compared to noncontrast MRA, although only a single case of thrombus was included in the analysis [43]. On the other hand, in 6 Workup of Noncerebral Systemic Arterial Embolic Source a small analysis which included 9 patients with aortic thrombus, contrast-enhanced MRA had a lower thrombus detection rate compared to a noncontrast examination, although this finding was not statistically significant [44]. Data comparing MRA of the chest to other imaging modalities are lacking. MRA Chest Without IV Contrast In some conditions or clinical scenarios, there may be a high suspicion that the embolic source is in the thoracic aorta and an MRA limited to the chest may be diagnostic. One small study found this examination to have a higher detection rate for aortic thrombus when compared with contrast-enhanced MRA, although the difference was not statistically significant [44]. In another study, sensitivity, specificity, and diagnostic accuracy of unenhanced steady- state free precession MRA were 100% for the detection of thoracic aorta pathology compared to a contrast-enhanced MRA reference standard; however, this analysis only included 1 case of mural thrombus [43]. Data comparing MRA of the chest to other imaging modalities is lacking.

Workup of Noncerebral Systemic Arterial Embolic Source. A number of small studies have used CTA to detect aortic mural thrombus that was suspected of embolization [1,12-14,42]. Specific data on the sensitivity and specificity of this imaging modality are lacking. MRA Chest Without and With IV Contrast In some conditions or clinical scenarios, there may be a high suspicion that the embolic source is in the thoracic aorta and an MRA limited to the chest may be diagnostic. In 1 study, detection of thoracic aorta pathology by contrast-enhanced chest MRA was equivalent in sensitivity, specificity, and diagnostic accuracy compared to noncontrast MRA, although only a single case of thrombus was included in the analysis [43]. On the other hand, in 6 Workup of Noncerebral Systemic Arterial Embolic Source a small analysis which included 9 patients with aortic thrombus, contrast-enhanced MRA had a lower thrombus detection rate compared to a noncontrast examination, although this finding was not statistically significant [44]. Data comparing MRA of the chest to other imaging modalities are lacking. MRA Chest Without IV Contrast In some conditions or clinical scenarios, there may be a high suspicion that the embolic source is in the thoracic aorta and an MRA limited to the chest may be diagnostic. One small study found this examination to have a higher detection rate for aortic thrombus when compared with contrast-enhanced MRA, although the difference was not statistically significant [44]. In another study, sensitivity, specificity, and diagnostic accuracy of unenhanced steady- state free precession MRA were 100% for the detection of thoracic aorta pathology compared to a contrast-enhanced MRA reference standard; however, this analysis only included 1 case of mural thrombus [43]. Data comparing MRA of the chest to other imaging modalities is lacking.

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MRA Chest and Abdomen Without and With IV Contrast MRA of the chest and abdomen without and with IV contrast can be used to evaluate for presence of an embolic source in the aorta in its entirety. In 1 study, detection of thoracic aorta pathology by contrast-enhanced chest MRA was equivalent in sensitivity, specificity, and diagnostic accuracy compared to noncontrast MRA, although only a single case of thrombus was included in the analysis [43]. On the other hand, in a small analysis which included 9 patients with aortic thrombus, contrast-enhanced MRA had a lower thrombus detection rate compared to a noncontrast examination, although this finding was not statistically significant [44]. Contrast-enhanced MRA of the abdomen has been used for intraluminal thrombus detection in the setting of aneurysms, although comparative data are insufficient [56-58]. Data comparing MRA of the chest and abdomen to other imaging modalities are lacking. MRA Chest and Abdomen Without IV Contrast Chest and abdomen MRA without IV contrast can be used to evaluate for the presence of an embolic source in the aorta in its entirety. One small study found this examination to have a higher detection rate for aortic thrombus when compared with contrast-enhanced MRA, although the difference was not statistically significant [44]. In another study, sensitivity, specificity, and diagnostic accuracy of unenhanced steady-state free precession MRA were 100% for the detection of thoracic aorta pathology compared to a contrast-enhanced MRA reference standard; however, this analysis only included 1 case of mural thrombus [43]. Noncontrast MRA has been used for the detection of abdominal aortic intraluminal thrombus, although there are insufficient data comparing it to contrast- enhanced MRA [56-58]. Data comparing MRA of the chest and abdomen to other imaging modalities are lacking.

Workup of Noncerebral Systemic Arterial Embolic Source. MRA Chest and Abdomen Without and With IV Contrast MRA of the chest and abdomen without and with IV contrast can be used to evaluate for presence of an embolic source in the aorta in its entirety. In 1 study, detection of thoracic aorta pathology by contrast-enhanced chest MRA was equivalent in sensitivity, specificity, and diagnostic accuracy compared to noncontrast MRA, although only a single case of thrombus was included in the analysis [43]. On the other hand, in a small analysis which included 9 patients with aortic thrombus, contrast-enhanced MRA had a lower thrombus detection rate compared to a noncontrast examination, although this finding was not statistically significant [44]. Contrast-enhanced MRA of the abdomen has been used for intraluminal thrombus detection in the setting of aneurysms, although comparative data are insufficient [56-58]. Data comparing MRA of the chest and abdomen to other imaging modalities are lacking. MRA Chest and Abdomen Without IV Contrast Chest and abdomen MRA without IV contrast can be used to evaluate for the presence of an embolic source in the aorta in its entirety. One small study found this examination to have a higher detection rate for aortic thrombus when compared with contrast-enhanced MRA, although the difference was not statistically significant [44]. In another study, sensitivity, specificity, and diagnostic accuracy of unenhanced steady-state free precession MRA were 100% for the detection of thoracic aorta pathology compared to a contrast-enhanced MRA reference standard; however, this analysis only included 1 case of mural thrombus [43]. Noncontrast MRA has been used for the detection of abdominal aortic intraluminal thrombus, although there are insufficient data comparing it to contrast- enhanced MRA [56-58]. Data comparing MRA of the chest and abdomen to other imaging modalities are lacking.

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MRI Heart Function and Morphology Without and With IV Contrast Cardiac MR is a noninvasive imaging study that can reliably detect intracardiac thrombus as well as valvular and neoplastic pathologies. A meta-analysis of 7 studies showed that delayed contrast-enhanced cardiac MR had a pooled sensitivity of 100% and a specificity of 99% for detecting left atrial and left atrial appendage thrombus in patients with atrial fibrillation [45]. In another meta-analysis, there was no significant difference in sensitivity and specificity between cardiac CT and cardiac MR in the detection of left atrial appendage thrombus [29]. Contrast- enhanced cardiac MR had a sensitivity of 88% and a specificity of 99% compared to surgical or pathological confirmation of left ventricular thrombus [46]. Cardiac MR is also an accurate imaging modality for the evaluation of valvular disease, including aortic and mitral valve vegetations, which can dislodge and result in arterial embolism [37,47]. Additionally, cardiac MR offers detailed soft tissue characterization for the analysis of benign and malignant intracardiac neoplasms [39,48]. MRI Heart Function and Morphology Without IV Contrast Cardiac MR without contrast provides a detailed anatomic evaluation of the heart chambers. In the workup of embolic sources, the primary role of cardiac MR is in the identification of intracardiac thrombus. A meta-analysis of 7 studies showed that cine cardiac MR had a pooled sensitivity of 91% and a specificity of 93% for detecting left atrial and left atrial appendage thrombus in patients with atrial fibrillation [45]. Furthermore, cine cardiac MR had an 82% sensitivity and 100% specificity in detecting left ventricle thrombus in postmyocardial infarction patients compared to a standard delayed enhancement cardiac MR [49].

Workup of Noncerebral Systemic Arterial Embolic Source. MRI Heart Function and Morphology Without and With IV Contrast Cardiac MR is a noninvasive imaging study that can reliably detect intracardiac thrombus as well as valvular and neoplastic pathologies. A meta-analysis of 7 studies showed that delayed contrast-enhanced cardiac MR had a pooled sensitivity of 100% and a specificity of 99% for detecting left atrial and left atrial appendage thrombus in patients with atrial fibrillation [45]. In another meta-analysis, there was no significant difference in sensitivity and specificity between cardiac CT and cardiac MR in the detection of left atrial appendage thrombus [29]. Contrast- enhanced cardiac MR had a sensitivity of 88% and a specificity of 99% compared to surgical or pathological confirmation of left ventricular thrombus [46]. Cardiac MR is also an accurate imaging modality for the evaluation of valvular disease, including aortic and mitral valve vegetations, which can dislodge and result in arterial embolism [37,47]. Additionally, cardiac MR offers detailed soft tissue characterization for the analysis of benign and malignant intracardiac neoplasms [39,48]. MRI Heart Function and Morphology Without IV Contrast Cardiac MR without contrast provides a detailed anatomic evaluation of the heart chambers. In the workup of embolic sources, the primary role of cardiac MR is in the identification of intracardiac thrombus. A meta-analysis of 7 studies showed that cine cardiac MR had a pooled sensitivity of 91% and a specificity of 93% for detecting left atrial and left atrial appendage thrombus in patients with atrial fibrillation [45]. Furthermore, cine cardiac MR had an 82% sensitivity and 100% specificity in detecting left ventricle thrombus in postmyocardial infarction patients compared to a standard delayed enhancement cardiac MR [49].

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Cardiac MR without contrast is also capable of identifying valvular pathology and cardiac neoplasms, although data on its applicability in the setting of systemic arterial embolism are lacking. US Duplex Doppler Abdomen There is no relevant literature to support the use of Doppler US of the abdomen as an initial imaging modality in the evaluation of the source of known embolic mesenteric/renal arterial occlusion. However, some imaging 7 Workup of Noncerebral Systemic Arterial Embolic Source protocols may include limited views of the abdominal aorta that may detect intraluminal aortic thrombus or significant atherosclerotic disease [56]. US Echocardiography Transesophageal TEE is an invasive diagnostic study with the ability to detect cardiac pathology predisposed to embolism. TEE has a sensitivity of 93% to 100% and a specificity of 95% to 99% for detecting left atrial appendage thrombus when compared to intraoperative findings [31,50,51]. Furthermore, TEE can evaluate left ventricular systolic dysfunction, spontaneous echo contrast, slow left atrial appendage peak flow velocities, and complex left atrial appendage morphologies, which are all associated with left atrial thrombus and thromboembolic risk [2,4]. In addition, TEE can detect left ventricular thrombus, with 1 study reporting a 40% sensitivity and a 96% specificity for the modality compared to findings at surgery or pathology [46]. Proximal aortic thrombus can also be assessed using TEE, although evaluation is limited by blind spots (distal ascending aorta and proximal aortic arch) owing to air in the trachea [10,13]. Detection of valvular disease and intracardiac neoplasms can also be accomplished with TEE. US Echocardiography Transthoracic Resting TTE is a noninvasive imaging modality capable of detecting cardiac pathology susceptible to embolism.

Workup of Noncerebral Systemic Arterial Embolic Source. Cardiac MR without contrast is also capable of identifying valvular pathology and cardiac neoplasms, although data on its applicability in the setting of systemic arterial embolism are lacking. US Duplex Doppler Abdomen There is no relevant literature to support the use of Doppler US of the abdomen as an initial imaging modality in the evaluation of the source of known embolic mesenteric/renal arterial occlusion. However, some imaging 7 Workup of Noncerebral Systemic Arterial Embolic Source protocols may include limited views of the abdominal aorta that may detect intraluminal aortic thrombus or significant atherosclerotic disease [56]. US Echocardiography Transesophageal TEE is an invasive diagnostic study with the ability to detect cardiac pathology predisposed to embolism. TEE has a sensitivity of 93% to 100% and a specificity of 95% to 99% for detecting left atrial appendage thrombus when compared to intraoperative findings [31,50,51]. Furthermore, TEE can evaluate left ventricular systolic dysfunction, spontaneous echo contrast, slow left atrial appendage peak flow velocities, and complex left atrial appendage morphologies, which are all associated with left atrial thrombus and thromboembolic risk [2,4]. In addition, TEE can detect left ventricular thrombus, with 1 study reporting a 40% sensitivity and a 96% specificity for the modality compared to findings at surgery or pathology [46]. Proximal aortic thrombus can also be assessed using TEE, although evaluation is limited by blind spots (distal ascending aorta and proximal aortic arch) owing to air in the trachea [10,13]. Detection of valvular disease and intracardiac neoplasms can also be accomplished with TEE. US Echocardiography Transthoracic Resting TTE is a noninvasive imaging modality capable of detecting cardiac pathology susceptible to embolism.

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TTE is inferior to TEE in the assessment of left atrial appendage thrombus because the transducer is distant from the left atrium when placed on the chest [52]. In 1 study, a cardiac embolic source was detected by TEE in about 40% of patients with normal TTE [53]. In another study, a cardiac embolic source was identified by TTE in 15% of the study group compared with 57% by TEE [54]. Sensitivity and specificity were 23% and 96%, respectively, for the detection of left ventricular thrombus compared to findings at surgery or pathology [46]. In the detection of left ventricle thrombus, contrast-enhanced TTE had a 64% sensitivity and 99% specificity compared to a delayed enhancement cardiac MR standard [49]. TTE can also be applied for the diagnosis of valvular disease and cardiac neoplasms. There is no evidence to support the use of TTE in the evaluation of aortic thrombus. Aortography Chest, Abdomen, and Pelvis Conventional catheter aortography has largely been replaced by noninvasive imaging modalities such as CTA and MRA given their high sensitivity/specificity for detecting aortic pathologies such as mural thrombus [16,17]. Aortography is typically used as an alternative diagnostic strategy following initial noninvasive imaging and when therapeutic interventions are being considered [11,17]. CT Heart Function and Morphology With IV Contrast The primary role of cardiac CT in the initial evaluation of lower extremity arterial embolic occlusion is in the workup of cardiac thrombus as a source. Multiple studies have established high rates of atrial thrombus detection by cardiac CT compared to TEE [18-27]. Meta-analyses have found sensitivities of 96% to 99% and specificities of 92% to 94% for detection of left atrial or left atrial appendage thrombus with cardiac CT compared to a TEE reference standard [28-30]. When compared to intraoperative findings, cardiac CT was 100% sensitive and 85% specific for finding left atrial thrombus [31].

Workup of Noncerebral Systemic Arterial Embolic Source. TTE is inferior to TEE in the assessment of left atrial appendage thrombus because the transducer is distant from the left atrium when placed on the chest [52]. In 1 study, a cardiac embolic source was detected by TEE in about 40% of patients with normal TTE [53]. In another study, a cardiac embolic source was identified by TTE in 15% of the study group compared with 57% by TEE [54]. Sensitivity and specificity were 23% and 96%, respectively, for the detection of left ventricular thrombus compared to findings at surgery or pathology [46]. In the detection of left ventricle thrombus, contrast-enhanced TTE had a 64% sensitivity and 99% specificity compared to a delayed enhancement cardiac MR standard [49]. TTE can also be applied for the diagnosis of valvular disease and cardiac neoplasms. There is no evidence to support the use of TTE in the evaluation of aortic thrombus. Aortography Chest, Abdomen, and Pelvis Conventional catheter aortography has largely been replaced by noninvasive imaging modalities such as CTA and MRA given their high sensitivity/specificity for detecting aortic pathologies such as mural thrombus [16,17]. Aortography is typically used as an alternative diagnostic strategy following initial noninvasive imaging and when therapeutic interventions are being considered [11,17]. CT Heart Function and Morphology With IV Contrast The primary role of cardiac CT in the initial evaluation of lower extremity arterial embolic occlusion is in the workup of cardiac thrombus as a source. Multiple studies have established high rates of atrial thrombus detection by cardiac CT compared to TEE [18-27]. Meta-analyses have found sensitivities of 96% to 99% and specificities of 92% to 94% for detection of left atrial or left atrial appendage thrombus with cardiac CT compared to a TEE reference standard [28-30]. When compared to intraoperative findings, cardiac CT was 100% sensitive and 85% specific for finding left atrial thrombus [31].

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Complex left atrial appendage morphologies, which predispose to thrombus formation, can also be characterized by cardiac CT [32-34]. Additionally, cardiac CT can differentiate left ventricular thrombus from the myocardial wall with 1 study demonstrating a sensitivity, specificity, and positive and negative predictive values of 94%, 97%, 94%, and 97%, respectively [35]. Studies have also demonstrated cardiac CT to have comparable accuracy to TEE for identification of vegetations in the setting of infective endocarditis, another potential source of arterial embolism [36-38]. Cardiac CT can identify cardiac neoplasms, both benign and malignant, which have the potential to shed and embolize to distal arterial beds [39,40]. CTA Chest With IV Contrast In some conditions or clinical scenarios, there may be a high suspicion that the embolic source is in the thoracic aorta and a CTA limited to the chest may be diagnostic. As such, multidetector chest CTA with IV contrast can be used to evaluate for at-risk atherosclerotic plaque or the presence of thrombus in the thoracic aorta. CTA is useful in the assessment of the size, extent, and location of an embolic source in the aorta, which can aid in management decisions [13,41]. A number of small studies have used chest CTA to detect aortic mural thrombus that was CTA Chest, Abdomen, and Pelvis With IV Contrast Multidetector CTA with IV contrast can be used to evaluate for the presence of at-risk atherosclerotic plaque or thrombus in the aorta in its entirety. CTA is useful in the assessment of the size, extent, and location of an embolic source in the aorta, which can aid in management decisions [13,41]. Aortic intraluminal thrombus is oftentimes associated with aneurysm, particularly in the abdomen, which is readily detected by CTA [56,57]. A number of small studies have used CTA to detect aortic mural thrombus that was suspected of embolization [1,12-14,42].

Workup of Noncerebral Systemic Arterial Embolic Source. Complex left atrial appendage morphologies, which predispose to thrombus formation, can also be characterized by cardiac CT [32-34]. Additionally, cardiac CT can differentiate left ventricular thrombus from the myocardial wall with 1 study demonstrating a sensitivity, specificity, and positive and negative predictive values of 94%, 97%, 94%, and 97%, respectively [35]. Studies have also demonstrated cardiac CT to have comparable accuracy to TEE for identification of vegetations in the setting of infective endocarditis, another potential source of arterial embolism [36-38]. Cardiac CT can identify cardiac neoplasms, both benign and malignant, which have the potential to shed and embolize to distal arterial beds [39,40]. CTA Chest With IV Contrast In some conditions or clinical scenarios, there may be a high suspicion that the embolic source is in the thoracic aorta and a CTA limited to the chest may be diagnostic. As such, multidetector chest CTA with IV contrast can be used to evaluate for at-risk atherosclerotic plaque or the presence of thrombus in the thoracic aorta. CTA is useful in the assessment of the size, extent, and location of an embolic source in the aorta, which can aid in management decisions [13,41]. A number of small studies have used chest CTA to detect aortic mural thrombus that was CTA Chest, Abdomen, and Pelvis With IV Contrast Multidetector CTA with IV contrast can be used to evaluate for the presence of at-risk atherosclerotic plaque or thrombus in the aorta in its entirety. CTA is useful in the assessment of the size, extent, and location of an embolic source in the aorta, which can aid in management decisions [13,41]. Aortic intraluminal thrombus is oftentimes associated with aneurysm, particularly in the abdomen, which is readily detected by CTA [56,57]. A number of small studies have used CTA to detect aortic mural thrombus that was suspected of embolization [1,12-14,42].

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Specific data on the sensitivity and specificity of this imaging modality are lacking. MRA Chest Without and With IV Contrast In some conditions or clinical scenarios, there may be a high suspicion that the embolic source is in the thoracic aorta and an MRA limited to the chest may be diagnostic. In 1 study, detection of thoracic aorta pathology by contrast-enhanced chest MRA was equivalent in sensitivity, specificity, and diagnostic accuracy compared to noncontrast MRA, although only a single case of thrombus was included in the analysis [43]. On the other hand, in a small analysis which included 9 patients with aortic thrombus, contrast-enhanced MRA had a lower thrombus detection rate compared to a noncontrast examination, although this finding was not statistically significant [44]. Data comparing MRA of the chest to other imaging modalities are lacking. MRA Chest Without IV Contrast In some conditions or clinical scenarios, there may be a high suspicion that the embolic source is in the thoracic aorta and an MRA limited to the chest may be diagnostic. One small study found this examination to have a higher detection rate for aortic thrombus when compared with contrast-enhanced MRA, although the difference was not statistically significant [44]. In another study, sensitivity, specificity, and diagnostic accuracy of unenhanced steady- state free precession MRA were 100% for the detection of thoracic aorta pathology compared to a contrast-enhanced MRA reference standard; however, this analysis only included 1 case of mural thrombus [43]. Data comparing MRA of the chest to other imaging modalities is lacking. MRA Chest, Abdomen, and Pelvis Without and With IV Contrast MRA of the chest, abdomen, and pelvis without and with IV contrast can be used to evaluate for the presence of an embolic source in the aorta in its entirety.

Workup of Noncerebral Systemic Arterial Embolic Source. Specific data on the sensitivity and specificity of this imaging modality are lacking. MRA Chest Without and With IV Contrast In some conditions or clinical scenarios, there may be a high suspicion that the embolic source is in the thoracic aorta and an MRA limited to the chest may be diagnostic. In 1 study, detection of thoracic aorta pathology by contrast-enhanced chest MRA was equivalent in sensitivity, specificity, and diagnostic accuracy compared to noncontrast MRA, although only a single case of thrombus was included in the analysis [43]. On the other hand, in a small analysis which included 9 patients with aortic thrombus, contrast-enhanced MRA had a lower thrombus detection rate compared to a noncontrast examination, although this finding was not statistically significant [44]. Data comparing MRA of the chest to other imaging modalities are lacking. MRA Chest Without IV Contrast In some conditions or clinical scenarios, there may be a high suspicion that the embolic source is in the thoracic aorta and an MRA limited to the chest may be diagnostic. One small study found this examination to have a higher detection rate for aortic thrombus when compared with contrast-enhanced MRA, although the difference was not statistically significant [44]. In another study, sensitivity, specificity, and diagnostic accuracy of unenhanced steady- state free precession MRA were 100% for the detection of thoracic aorta pathology compared to a contrast-enhanced MRA reference standard; however, this analysis only included 1 case of mural thrombus [43]. Data comparing MRA of the chest to other imaging modalities is lacking. MRA Chest, Abdomen, and Pelvis Without and With IV Contrast MRA of the chest, abdomen, and pelvis without and with IV contrast can be used to evaluate for the presence of an embolic source in the aorta in its entirety.

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Workup of Noncerebral Systemic Arterial Embolic Source

In 1 study, detection of thoracic aorta pathology by contrast-enhanced chest MRA was equivalent in sensitivity, specificity, and diagnostic accuracy compared to noncontrast MRA, although only a single case of thrombus was included in the analysis [43]. On the other hand, in a small analysis which included 9 patients with aortic thrombus, contrast-enhanced MRA had a lower thrombus detection rate compared to a noncontrast examination, although this finding was not statistically significant [44]. Contrast- enhanced MRA of the abdomen has been used for intraluminal thrombus detection in the setting of aneurysms, although comparative data is insufficient [56-58]. Data comparing MRA of the chest, abdomen, and pelvis to other imaging modalities is lacking. MRA Chest, Abdomen, and Pelvis Without IV Contrast Chest, abdomen, and pelvis MRA without IV contrast can be used to evaluate for the presence of an embolic source in the aorta in its entirety. One small study found this examination to have a higher detection rate for aortic thrombus when compared with contrast-enhanced MRA, although the difference was not statistically significant [44]. In another study, sensitivity, specificity, and diagnostic accuracy of unenhanced steady-state free precession MRA were 100% for the detection of thoracic aorta pathology compared to a contrast-enhanced MRA reference standard, however this analysis only included 1 case of mural thrombus [43]. Noncontrast MRA has been used for the detection of abdominal aortic intraluminal thrombus, although there is insufficient data comparing it to contrast- enhanced MRA [56-58]. Data comparing MRA of the chest, abdomen, and pelvis to other imaging modalities is lacking. MRI Heart Function and Morphology Without and With IV Contrast Cardiac MR is a noninvasive imaging study that can reliably detect intracardiac thrombus as well as valvular and neoplastic pathologies.

Workup of Noncerebral Systemic Arterial Embolic Source. In 1 study, detection of thoracic aorta pathology by contrast-enhanced chest MRA was equivalent in sensitivity, specificity, and diagnostic accuracy compared to noncontrast MRA, although only a single case of thrombus was included in the analysis [43]. On the other hand, in a small analysis which included 9 patients with aortic thrombus, contrast-enhanced MRA had a lower thrombus detection rate compared to a noncontrast examination, although this finding was not statistically significant [44]. Contrast- enhanced MRA of the abdomen has been used for intraluminal thrombus detection in the setting of aneurysms, although comparative data is insufficient [56-58]. Data comparing MRA of the chest, abdomen, and pelvis to other imaging modalities is lacking. MRA Chest, Abdomen, and Pelvis Without IV Contrast Chest, abdomen, and pelvis MRA without IV contrast can be used to evaluate for the presence of an embolic source in the aorta in its entirety. One small study found this examination to have a higher detection rate for aortic thrombus when compared with contrast-enhanced MRA, although the difference was not statistically significant [44]. In another study, sensitivity, specificity, and diagnostic accuracy of unenhanced steady-state free precession MRA were 100% for the detection of thoracic aorta pathology compared to a contrast-enhanced MRA reference standard, however this analysis only included 1 case of mural thrombus [43]. Noncontrast MRA has been used for the detection of abdominal aortic intraluminal thrombus, although there is insufficient data comparing it to contrast- enhanced MRA [56-58]. Data comparing MRA of the chest, abdomen, and pelvis to other imaging modalities is lacking. MRI Heart Function and Morphology Without and With IV Contrast Cardiac MR is a noninvasive imaging study that can reliably detect intracardiac thrombus as well as valvular and neoplastic pathologies.

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Workup of Noncerebral Systemic Arterial Embolic Source

A meta-analysis of 7 studies showed that delayed contrast-enhanced cardiac MR had a pooled sensitivity of 100% and a specificity of 99% for detecting left atrial and left atrial appendage thrombus in patients with atrial fibrillation [45]. In another meta-analysis, there was no significant difference in sensitivity and specificity between cardiac CT and cardiac MR in the detection of left atrial appendage thrombus [29]. Contrast- enhanced cardiac MR had a sensitivity of 88% and a specificity of 99% compared to surgical or pathological 9 Workup of Noncerebral Systemic Arterial Embolic Source confirmation of left ventricular thrombus [46]. Cardiac MR is also an accurate imaging modality for the evaluation of valvular disease, including aortic and mitral valve vegetations, which can dislodge and result in arterial embolism [37,47]. Additionally, cardiac MR offers detailed soft tissue characterization for the analysis of benign and malignant intracardiac neoplasms [39,48]. MRI Heart Function and Morphology Without IV Contrast Cardiac MR without contrast provides a detailed anatomic evaluation of the heart chambers. In the workup of embolic sources, the primary role of cardiac MR is in the identification of intracardiac thrombus. A meta-analysis of 7 studies showed that cine cardiac MR had a pooled sensitivity of 91% and a specificity of 93% for detecting left atrial and left atrial appendage thrombus in patients with atrial fibrillation [45]. Furthermore, cine cardiac MR had an 82% sensitivity and a 100% specificity in detecting left ventricle thrombus in postmyocardial infarction patients compared with a standard delayed enhancement cardiac MR [49]. Cardiac MR without contrast is also capable of identifying valvular pathology and cardiac neoplasms, although data on its applicability in the setting of systemic arterial embolism are lacking.

Workup of Noncerebral Systemic Arterial Embolic Source. A meta-analysis of 7 studies showed that delayed contrast-enhanced cardiac MR had a pooled sensitivity of 100% and a specificity of 99% for detecting left atrial and left atrial appendage thrombus in patients with atrial fibrillation [45]. In another meta-analysis, there was no significant difference in sensitivity and specificity between cardiac CT and cardiac MR in the detection of left atrial appendage thrombus [29]. Contrast- enhanced cardiac MR had a sensitivity of 88% and a specificity of 99% compared to surgical or pathological 9 Workup of Noncerebral Systemic Arterial Embolic Source confirmation of left ventricular thrombus [46]. Cardiac MR is also an accurate imaging modality for the evaluation of valvular disease, including aortic and mitral valve vegetations, which can dislodge and result in arterial embolism [37,47]. Additionally, cardiac MR offers detailed soft tissue characterization for the analysis of benign and malignant intracardiac neoplasms [39,48]. MRI Heart Function and Morphology Without IV Contrast Cardiac MR without contrast provides a detailed anatomic evaluation of the heart chambers. In the workup of embolic sources, the primary role of cardiac MR is in the identification of intracardiac thrombus. A meta-analysis of 7 studies showed that cine cardiac MR had a pooled sensitivity of 91% and a specificity of 93% for detecting left atrial and left atrial appendage thrombus in patients with atrial fibrillation [45]. Furthermore, cine cardiac MR had an 82% sensitivity and a 100% specificity in detecting left ventricle thrombus in postmyocardial infarction patients compared with a standard delayed enhancement cardiac MR [49]. Cardiac MR without contrast is also capable of identifying valvular pathology and cardiac neoplasms, although data on its applicability in the setting of systemic arterial embolism are lacking.

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US Duplex Doppler Abdomen There is no relevant literature to support the use of Doppler US of the abdomen as an initial imaging modality in the evaluation of the source of known embolic lower extremity arterial occlusion. However, some imaging protocols may include limited views of the abdominal aorta, which may detect intraluminal aortic thrombus or significant atherosclerotic disease [56]. US Echocardiography Transesophageal TEE is an invasive diagnostic study with the ability to detect cardiac pathology predisposed to embolism. TEE has a sensitivity of 93% to 100% and a specificity of 95% to 99% for detecting left atrial appendage thrombus when compared to intraoperative findings [31,50,51]. Furthermore, TEE can evaluate left ventricular systolic dysfunction, spontaneous echo contrast, slow left atrial appendage peak flow velocities, and complex left atrial appendage morphologies, which are all associated with left atrial thrombus and thromboembolic risk [2,4]. In addition, TEE can detect left ventricular thrombus, with 1 study reporting a 40% sensitivity and a 96% specificity for the modality compared to findings at surgery or pathology [46]. Proximal aortic thrombus can also be assessed using TEE, although evaluation is limited by blind spots (distal ascending aorta and proximal aortic arch) owing to air in the trachea [10,13]. Detection of valvular disease and intracardiac neoplasms can also be accomplished with TEE. US Echocardiography Transthoracic Resting TTE is a noninvasive imaging modality capable of detecting cardiac pathology susceptible to embolism. TTE is inferior to TEE in the assessment of left atrial appendage thrombus because the transducer is distant from the left atrium when placed on the chest [52]. In 1 study, a cardiac embolic source was detected by TEE in about 40% of patients with normal TTE [53]. In another study, a cardiac embolic source was identified by TTE in 15% of the study group compared with 57% by TEE [54].

Workup of Noncerebral Systemic Arterial Embolic Source. US Duplex Doppler Abdomen There is no relevant literature to support the use of Doppler US of the abdomen as an initial imaging modality in the evaluation of the source of known embolic lower extremity arterial occlusion. However, some imaging protocols may include limited views of the abdominal aorta, which may detect intraluminal aortic thrombus or significant atherosclerotic disease [56]. US Echocardiography Transesophageal TEE is an invasive diagnostic study with the ability to detect cardiac pathology predisposed to embolism. TEE has a sensitivity of 93% to 100% and a specificity of 95% to 99% for detecting left atrial appendage thrombus when compared to intraoperative findings [31,50,51]. Furthermore, TEE can evaluate left ventricular systolic dysfunction, spontaneous echo contrast, slow left atrial appendage peak flow velocities, and complex left atrial appendage morphologies, which are all associated with left atrial thrombus and thromboembolic risk [2,4]. In addition, TEE can detect left ventricular thrombus, with 1 study reporting a 40% sensitivity and a 96% specificity for the modality compared to findings at surgery or pathology [46]. Proximal aortic thrombus can also be assessed using TEE, although evaluation is limited by blind spots (distal ascending aorta and proximal aortic arch) owing to air in the trachea [10,13]. Detection of valvular disease and intracardiac neoplasms can also be accomplished with TEE. US Echocardiography Transthoracic Resting TTE is a noninvasive imaging modality capable of detecting cardiac pathology susceptible to embolism. TTE is inferior to TEE in the assessment of left atrial appendage thrombus because the transducer is distant from the left atrium when placed on the chest [52]. In 1 study, a cardiac embolic source was detected by TEE in about 40% of patients with normal TTE [53]. In another study, a cardiac embolic source was identified by TTE in 15% of the study group compared with 57% by TEE [54].

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Workup of Noncerebral Systemic Arterial Embolic Source

Sensitivity and specificity were 23% and 96%, respectively, for the detection of left ventricular thrombus compared to findings at surgery or pathology [46]. In the detection of left ventricle thrombus, contrast-enhanced TTE had a 64% sensitivity and a 99% specificity compared to a delayed enhancement cardiac MR standard [49]. TTE can also be applied for the diagnosis of valvular disease and cardiac neoplasms. There is no evidence to support the use of TTE in the evaluation of aortic thrombus. Variant 4: Known multiorgan system arterial occlusions. Suspected embolic etiology. Next imaging study to determine source. The variant assumes that multiorgan arterial occlusions have already been established. Typically, these diagnoses are made by CTA, arteriography, or MRA, although the clinical examination or another imaging study could also be used. CT Heart Function and Morphology With IV Contrast The primary role of cardiac CT in the initial evaluation of multiorgan system arterial embolic occlusion is in the workup of cardiac thrombus as a source. Multiple studies have established high rates of atrial thrombus detection by cardiac CT compared to TEE [18-27]. Meta-analyses have found sensitivities of 96% to 99% and specificities of 92% to 94% for detection of left atrial or left atrial appendage thrombus with cardiac CT compared to a TEE reference standard [28-30]. When compared with intraoperative findings, cardiac CT was 100% sensitive and 85% specific for finding left atrial thrombus [31]. Complex left atrial appendage morphologies, which predispose to thrombus formation, can also be characterized by cardiac CT [32-34]. Additionally, cardiac CT can differentiate left ventricular thrombus from the myocardial wall, with 1 study demonstrating a sensitivity, specificity, and 10 Workup of Noncerebral Systemic Arterial Embolic Source positive and negative predictive values of 94%, 97%, 94%, and 97%, respectively [35].

Workup of Noncerebral Systemic Arterial Embolic Source. Sensitivity and specificity were 23% and 96%, respectively, for the detection of left ventricular thrombus compared to findings at surgery or pathology [46]. In the detection of left ventricle thrombus, contrast-enhanced TTE had a 64% sensitivity and a 99% specificity compared to a delayed enhancement cardiac MR standard [49]. TTE can also be applied for the diagnosis of valvular disease and cardiac neoplasms. There is no evidence to support the use of TTE in the evaluation of aortic thrombus. Variant 4: Known multiorgan system arterial occlusions. Suspected embolic etiology. Next imaging study to determine source. The variant assumes that multiorgan arterial occlusions have already been established. Typically, these diagnoses are made by CTA, arteriography, or MRA, although the clinical examination or another imaging study could also be used. CT Heart Function and Morphology With IV Contrast The primary role of cardiac CT in the initial evaluation of multiorgan system arterial embolic occlusion is in the workup of cardiac thrombus as a source. Multiple studies have established high rates of atrial thrombus detection by cardiac CT compared to TEE [18-27]. Meta-analyses have found sensitivities of 96% to 99% and specificities of 92% to 94% for detection of left atrial or left atrial appendage thrombus with cardiac CT compared to a TEE reference standard [28-30]. When compared with intraoperative findings, cardiac CT was 100% sensitive and 85% specific for finding left atrial thrombus [31]. Complex left atrial appendage morphologies, which predispose to thrombus formation, can also be characterized by cardiac CT [32-34]. Additionally, cardiac CT can differentiate left ventricular thrombus from the myocardial wall, with 1 study demonstrating a sensitivity, specificity, and 10 Workup of Noncerebral Systemic Arterial Embolic Source positive and negative predictive values of 94%, 97%, 94%, and 97%, respectively [35].

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Studies have also demonstrated cardiac CT to have comparable accuracy to TEE for identification of vegetations in the setting of infective endocarditis, another potential source of arterial embolism [36-38]. Cardiac CT can identify cardiac neoplasms, both benign and malignant, which have the potential to shed and embolize to distal arterial beds [39,40]. CTA Chest With IV Contrast In some conditions or clinical scenarios, there may be a high suspicion that the embolic source is in the thoracic aorta, and a CTA limited to the chest may be diagnostic. As such, multidetector chest CTA with IV contrast can be used to evaluate for at-risk atherosclerotic plaque or the presence of thrombus in the thoracic aorta. CTA is useful in the assessment of the size, extent, and location of an embolic source in the aorta, which can aid in management decisions [13,41]. A number of small studies have used chest CTA to detect aortic mural thrombus that was suspected of embolization [1,12-14,42]. Specific data on the sensitivity and specificity of this imaging modality are lacking. CTA Chest, Abdomen, and Pelvis With IV contrast Multidetector CTA with IV contrast can be used to evaluate for the presence of at-risk atherosclerotic plaque or thrombus in the aorta in its entirety. CTA is useful in the assessment of the size, extent, and location of an embolic source in the aorta, which can aid in management decisions [13,41]. Aortic intraluminal thrombus is oftentimes associated with aneurysm, particularly in the abdomen, which is readily detected by CTA [56,57]. A number of small studies have used CTA to detect aortic mural thrombus that was suspected of embolization [1,12-14,42]. Specific data on the sensitivity and specificity of this imaging modality are lacking. MRA Chest Without and With IV Contrast In some conditions or clinical scenarios, there may be a high suspicion that the embolic source is in the thoracic aorta and an MRA limited to the chest may be diagnostic.

Workup of Noncerebral Systemic Arterial Embolic Source. Studies have also demonstrated cardiac CT to have comparable accuracy to TEE for identification of vegetations in the setting of infective endocarditis, another potential source of arterial embolism [36-38]. Cardiac CT can identify cardiac neoplasms, both benign and malignant, which have the potential to shed and embolize to distal arterial beds [39,40]. CTA Chest With IV Contrast In some conditions or clinical scenarios, there may be a high suspicion that the embolic source is in the thoracic aorta, and a CTA limited to the chest may be diagnostic. As such, multidetector chest CTA with IV contrast can be used to evaluate for at-risk atherosclerotic plaque or the presence of thrombus in the thoracic aorta. CTA is useful in the assessment of the size, extent, and location of an embolic source in the aorta, which can aid in management decisions [13,41]. A number of small studies have used chest CTA to detect aortic mural thrombus that was suspected of embolization [1,12-14,42]. Specific data on the sensitivity and specificity of this imaging modality are lacking. CTA Chest, Abdomen, and Pelvis With IV contrast Multidetector CTA with IV contrast can be used to evaluate for the presence of at-risk atherosclerotic plaque or thrombus in the aorta in its entirety. CTA is useful in the assessment of the size, extent, and location of an embolic source in the aorta, which can aid in management decisions [13,41]. Aortic intraluminal thrombus is oftentimes associated with aneurysm, particularly in the abdomen, which is readily detected by CTA [56,57]. A number of small studies have used CTA to detect aortic mural thrombus that was suspected of embolization [1,12-14,42]. Specific data on the sensitivity and specificity of this imaging modality are lacking. MRA Chest Without and With IV Contrast In some conditions or clinical scenarios, there may be a high suspicion that the embolic source is in the thoracic aorta and an MRA limited to the chest may be diagnostic.

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In 1 study, detection of thoracic aorta pathology by contrast-enhanced chest MRA was equivalent in sensitivity, specificity, and diagnostic accuracy compared to noncontrast MRA, although only a single case of thrombus was included in the analysis [43]. On the other hand, in a small analysis which included 9 patients with aortic thrombus, contrast-enhanced MRA had a lower thrombus detection rate compared to a noncontrast examination, although this finding was not statistically significant [44]. Data comparing MRA of the chest to other imaging modalities are lacking. MRA Chest Without IV Contrast In some conditions or clinical scenarios, there may be a high suspicion that the embolic source is in the thoracic aorta and an MRA limited to the chest may be diagnostic. One small study found this examination to have a higher detection rate for aortic thrombus when compared with contrast-enhanced MRA, although the difference was not statistically significant [44]. In another study, sensitivity, specificity, and diagnostic accuracy of unenhanced steady- state free precession MRA were 100% for the detection of thoracic aorta pathology compared to a contrast-enhanced MRA reference standard; however, this analysis only included 1 case of mural thrombus [43]. Data comparing MRA of the chest to other imaging modalities is lacking. MRA Chest, Abdomen, and Pelvis Without and With IV Contrast MRA of the chest, abdomen, and pelvis without and with IV contrast can be used to evaluate for the presence of an embolic source in the aorta in its entirety. In 1 study, detection of thoracic aorta pathology by contrast-enhanced chest MRA was equivalent in sensitivity, specificity, and diagnostic accuracy compared to noncontrast MRA, although only a single case of thrombus was included in the analysis [43].

Workup of Noncerebral Systemic Arterial Embolic Source. In 1 study, detection of thoracic aorta pathology by contrast-enhanced chest MRA was equivalent in sensitivity, specificity, and diagnostic accuracy compared to noncontrast MRA, although only a single case of thrombus was included in the analysis [43]. On the other hand, in a small analysis which included 9 patients with aortic thrombus, contrast-enhanced MRA had a lower thrombus detection rate compared to a noncontrast examination, although this finding was not statistically significant [44]. Data comparing MRA of the chest to other imaging modalities are lacking. MRA Chest Without IV Contrast In some conditions or clinical scenarios, there may be a high suspicion that the embolic source is in the thoracic aorta and an MRA limited to the chest may be diagnostic. One small study found this examination to have a higher detection rate for aortic thrombus when compared with contrast-enhanced MRA, although the difference was not statistically significant [44]. In another study, sensitivity, specificity, and diagnostic accuracy of unenhanced steady- state free precession MRA were 100% for the detection of thoracic aorta pathology compared to a contrast-enhanced MRA reference standard; however, this analysis only included 1 case of mural thrombus [43]. Data comparing MRA of the chest to other imaging modalities is lacking. MRA Chest, Abdomen, and Pelvis Without and With IV Contrast MRA of the chest, abdomen, and pelvis without and with IV contrast can be used to evaluate for the presence of an embolic source in the aorta in its entirety. In 1 study, detection of thoracic aorta pathology by contrast-enhanced chest MRA was equivalent in sensitivity, specificity, and diagnostic accuracy compared to noncontrast MRA, although only a single case of thrombus was included in the analysis [43].

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Workup of Noncerebral Systemic Arterial Embolic Source

On the other hand, in a small analysis which included 9 patients with aortic thrombus, contrast-enhanced MRA had a lower thrombus detection rate compared to a noncontrast examination, although this finding was not statistically significant [44]. Contrast- enhanced MRA of the abdomen has been used for intraluminal thrombus detection in the setting of aneurysms, although comparative data is insufficient [56-58]. Data comparing MRA of the chest, abdomen, and pelvis to other imaging modalities is lacking. MRA Chest, Abdomen, and Pelvis Without IV Contrast Chest, abdomen, and pelvis MRA without IV contrast can be used to evaluate for the presence of an embolic source in the aorta in its entirety. One small study found this examination to have a higher detection rate for aortic thrombus when compared with contrast-enhanced MRA, although the difference was not statistically significant [44]. In another study, sensitivity, specificity, and diagnostic accuracy of unenhanced steady-state free precession MRA were 100% for the detection of thoracic aorta pathology compared to a contrast-enhanced MRA reference standard, however this analysis only included 1 case of mural thrombus [43]. Noncontrast MRA has been used for the 11 Workup of Noncerebral Systemic Arterial Embolic Source detection of abdominal aortic intraluminal thrombus, although there is insufficient data comparing it to contrast- enhanced MRA [56-58]. Data comparing MRA of the chest, abdomen, and pelvis to other imaging modalities is lacking. MRI Heart Function and Morphology Without and With IV Contrast Cardiac MR is a noninvasive imaging study that can reliably detect intracardiac thrombus as well as valvular and neoplastic pathologies. A meta-analysis of 7 studies showed that delayed contrast-enhanced cardiac MR had a pooled sensitivity of 100% and a specificity of 99% for detecting left atrial and left atrial appendage thrombus in patients with atrial fibrillation [45].

Workup of Noncerebral Systemic Arterial Embolic Source. On the other hand, in a small analysis which included 9 patients with aortic thrombus, contrast-enhanced MRA had a lower thrombus detection rate compared to a noncontrast examination, although this finding was not statistically significant [44]. Contrast- enhanced MRA of the abdomen has been used for intraluminal thrombus detection in the setting of aneurysms, although comparative data is insufficient [56-58]. Data comparing MRA of the chest, abdomen, and pelvis to other imaging modalities is lacking. MRA Chest, Abdomen, and Pelvis Without IV Contrast Chest, abdomen, and pelvis MRA without IV contrast can be used to evaluate for the presence of an embolic source in the aorta in its entirety. One small study found this examination to have a higher detection rate for aortic thrombus when compared with contrast-enhanced MRA, although the difference was not statistically significant [44]. In another study, sensitivity, specificity, and diagnostic accuracy of unenhanced steady-state free precession MRA were 100% for the detection of thoracic aorta pathology compared to a contrast-enhanced MRA reference standard, however this analysis only included 1 case of mural thrombus [43]. Noncontrast MRA has been used for the 11 Workup of Noncerebral Systemic Arterial Embolic Source detection of abdominal aortic intraluminal thrombus, although there is insufficient data comparing it to contrast- enhanced MRA [56-58]. Data comparing MRA of the chest, abdomen, and pelvis to other imaging modalities is lacking. MRI Heart Function and Morphology Without and With IV Contrast Cardiac MR is a noninvasive imaging study that can reliably detect intracardiac thrombus as well as valvular and neoplastic pathologies. A meta-analysis of 7 studies showed that delayed contrast-enhanced cardiac MR had a pooled sensitivity of 100% and a specificity of 99% for detecting left atrial and left atrial appendage thrombus in patients with atrial fibrillation [45].

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Workup of Noncerebral Systemic Arterial Embolic Source

In another meta-analysis, there was no significant difference in sensitivity and specificity between cardiac CT and cardiac MR in the detection of left atrial appendage thrombus [29]. Contrast- enhanced cardiac MR had a sensitivity of 88% and a specificity of 99% compared to surgical or pathological confirmation of left ventricular thrombus [46]. Cardiac MR is also an accurate imaging modality for the evaluation of valvular disease, including aortic and mitral valve vegetations, which can dislodge and result in arterial embolism [37,47]. Additionally, cardiac MR offers detailed soft tissue characterization for the analysis of benign and malignant intracardiac neoplasms [39,48]. MRI Heart Function and Morphology Without IV Contrast Cardiac MR without contrast provides a detailed anatomic evaluation of the heart chambers. In the workup of embolic sources, the primary role of cardiac MR is in the identification of intracardiac thrombus. A meta-analysis of 7 studies showed that cine cardiac MR had a pooled sensitivity of 91% and a specificity of 93% for detecting left atrial and left atrial appendage thrombus in patients with atrial fibrillation [45]. Furthermore, cine cardiac MR had an 82% sensitivity and a 100% specificity in detecting left ventricle thrombus in postmyocardial infarction patients compared with a standard delayed enhancement cardiac MR [49]. Cardiac MR without contrast is also capable of identifying valvular pathology and cardiac neoplasms, although data on its applicability in the setting of systemic arterial thromboembolism are lacking. US Duplex Doppler Abdomen There is no relevant literature to support the use of Doppler US of the abdomen as an initial imaging modality in the evaluation of the source of known embolic multiorgan arterial occlusion. However, some imaging protocols may include limited views of the abdominal aorta, which may detect intraluminal aortic thrombus or significant atherosclerotic disease [56].

Workup of Noncerebral Systemic Arterial Embolic Source. In another meta-analysis, there was no significant difference in sensitivity and specificity between cardiac CT and cardiac MR in the detection of left atrial appendage thrombus [29]. Contrast- enhanced cardiac MR had a sensitivity of 88% and a specificity of 99% compared to surgical or pathological confirmation of left ventricular thrombus [46]. Cardiac MR is also an accurate imaging modality for the evaluation of valvular disease, including aortic and mitral valve vegetations, which can dislodge and result in arterial embolism [37,47]. Additionally, cardiac MR offers detailed soft tissue characterization for the analysis of benign and malignant intracardiac neoplasms [39,48]. MRI Heart Function and Morphology Without IV Contrast Cardiac MR without contrast provides a detailed anatomic evaluation of the heart chambers. In the workup of embolic sources, the primary role of cardiac MR is in the identification of intracardiac thrombus. A meta-analysis of 7 studies showed that cine cardiac MR had a pooled sensitivity of 91% and a specificity of 93% for detecting left atrial and left atrial appendage thrombus in patients with atrial fibrillation [45]. Furthermore, cine cardiac MR had an 82% sensitivity and a 100% specificity in detecting left ventricle thrombus in postmyocardial infarction patients compared with a standard delayed enhancement cardiac MR [49]. Cardiac MR without contrast is also capable of identifying valvular pathology and cardiac neoplasms, although data on its applicability in the setting of systemic arterial thromboembolism are lacking. US Duplex Doppler Abdomen There is no relevant literature to support the use of Doppler US of the abdomen as an initial imaging modality in the evaluation of the source of known embolic multiorgan arterial occlusion. However, some imaging protocols may include limited views of the abdominal aorta, which may detect intraluminal aortic thrombus or significant atherosclerotic disease [56].

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US Echocardiography Transesophageal TEE is an invasive diagnostic study with the ability to detect cardiac pathology predisposed to embolism. TEE has a sensitivity of 93% to 100% and a specificity of 95% to 99% for detecting left atrial appendage thrombus when compared with intraoperative findings [31,50,51]. Furthermore, TEE can evaluate left ventricular systolic dysfunction, spontaneous echo contrast, slow left atrial appendage peak flow velocities, and complex left atrial appendage morphologies, which are all associated with left atrial thrombus and thromboembolic risk [2,4]. In addition, TEE can detect left ventricular thrombus with 1 study reporting a 40% sensitivity and a 96% specificity for the modality compared to findings at surgery or pathology [46]. Proximal aortic thrombus can also be assessed using TEE, although evaluation is limited by blind spots (distal ascending aorta and proximal aortic arch) owing to air in the trachea [10,13]. Detection of valvular disease and intracardiac neoplasms can also be accomplished with TEE. US Echocardiography Transthoracic Resting TTE is a noninvasive imaging modality capable of detecting cardiac pathology susceptible to embolism. TTE is inferior to TEE in the assessment of left atrial appendage thrombus because the transducer is distant from the left atrium when placed on the chest [52]. In 1 study, a cardiac embolic source was detected by TEE in about 40% of patients with normal TTE [53]. In another study, a cardiac embolic source was identified by TTE in 15% of the study group compared with 57% by TEE [54]. Sensitivity and specificity were 23% and 96%, respectively, for the detection of left ventricular thrombus compared to findings at surgery or pathology [46]. In the detection of left ventricle thrombus, contrast-enhanced TTE had a 64% sensitivity and a 99% specificity compared to a delayed enhancement cardiac MR standard [49].

Workup of Noncerebral Systemic Arterial Embolic Source. US Echocardiography Transesophageal TEE is an invasive diagnostic study with the ability to detect cardiac pathology predisposed to embolism. TEE has a sensitivity of 93% to 100% and a specificity of 95% to 99% for detecting left atrial appendage thrombus when compared with intraoperative findings [31,50,51]. Furthermore, TEE can evaluate left ventricular systolic dysfunction, spontaneous echo contrast, slow left atrial appendage peak flow velocities, and complex left atrial appendage morphologies, which are all associated with left atrial thrombus and thromboembolic risk [2,4]. In addition, TEE can detect left ventricular thrombus with 1 study reporting a 40% sensitivity and a 96% specificity for the modality compared to findings at surgery or pathology [46]. Proximal aortic thrombus can also be assessed using TEE, although evaluation is limited by blind spots (distal ascending aorta and proximal aortic arch) owing to air in the trachea [10,13]. Detection of valvular disease and intracardiac neoplasms can also be accomplished with TEE. US Echocardiography Transthoracic Resting TTE is a noninvasive imaging modality capable of detecting cardiac pathology susceptible to embolism. TTE is inferior to TEE in the assessment of left atrial appendage thrombus because the transducer is distant from the left atrium when placed on the chest [52]. In 1 study, a cardiac embolic source was detected by TEE in about 40% of patients with normal TTE [53]. In another study, a cardiac embolic source was identified by TTE in 15% of the study group compared with 57% by TEE [54]. Sensitivity and specificity were 23% and 96%, respectively, for the detection of left ventricular thrombus compared to findings at surgery or pathology [46]. In the detection of left ventricle thrombus, contrast-enhanced TTE had a 64% sensitivity and a 99% specificity compared to a delayed enhancement cardiac MR standard [49].

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Cranial Neuropathy

Introduction/Background The human body has 12 paired cranial nerves (CNs) that provide specialized sensory and motor innervation to the head and neck region. As a group, the CNs have both sensory and motor components similar to those of the spinal nerves. Individually the CNs may be purely sensory, purely motor, or a mixture of both sensory and motor. Functions of the CNs may be divided into three sensory and three motor categories. The sensory group includes visceral sensory, which supplies sensory input from the internal organs; general sensory, which supplies tactile, pain, temperature, and other sensations; and special sensory, which includes the special senses of smell, vision, taste, hearing, and balance. Of the three motor functions, somatic motor nerves innervate muscles that develop from the body somites; branchial motor nerves innervate muscles derived from the branchial arches; and visceral motor nerves innervate the viscera, glands, and smooth muscle [1-4]. The CNs emerge in an orderly fashion from the rostral portion of the embryologically developing neural tube, which develops to form the brain. Anatomically, the 12 pairs of CNs are designated by numbers I-XII. The CNs include the olfactory (CN I), optic (CN II), oculomotor (CN III), trochlear (CN IV), trigeminal (CN V), abducens (CN VI), facial (CN VII), vestibulocochlear (CN VIII), glossopharyngeal (CN IX), vagus (CN X), spinal accessory (CN XI), and hypoglossal (CN XII) nerves. The olfactory (CN I) and optic (CN II) nerves are actually tracts formed from the telencephalon and diencephalon, respectively, and are not considered true nerves [4,5]. The CN nuclei arise in the brainstem, largely topologically arranged between the midbrain and the rostral cervical spine (CN XI). Current knowledge of CN anatomy has been improved by modern microsurgical techniques and endoscopic dissections, allowing visualization of the CN brainstem exit zones [3,4,6-13].

Cranial Neuropathy. Introduction/Background The human body has 12 paired cranial nerves (CNs) that provide specialized sensory and motor innervation to the head and neck region. As a group, the CNs have both sensory and motor components similar to those of the spinal nerves. Individually the CNs may be purely sensory, purely motor, or a mixture of both sensory and motor. Functions of the CNs may be divided into three sensory and three motor categories. The sensory group includes visceral sensory, which supplies sensory input from the internal organs; general sensory, which supplies tactile, pain, temperature, and other sensations; and special sensory, which includes the special senses of smell, vision, taste, hearing, and balance. Of the three motor functions, somatic motor nerves innervate muscles that develop from the body somites; branchial motor nerves innervate muscles derived from the branchial arches; and visceral motor nerves innervate the viscera, glands, and smooth muscle [1-4]. The CNs emerge in an orderly fashion from the rostral portion of the embryologically developing neural tube, which develops to form the brain. Anatomically, the 12 pairs of CNs are designated by numbers I-XII. The CNs include the olfactory (CN I), optic (CN II), oculomotor (CN III), trochlear (CN IV), trigeminal (CN V), abducens (CN VI), facial (CN VII), vestibulocochlear (CN VIII), glossopharyngeal (CN IX), vagus (CN X), spinal accessory (CN XI), and hypoglossal (CN XII) nerves. The olfactory (CN I) and optic (CN II) nerves are actually tracts formed from the telencephalon and diencephalon, respectively, and are not considered true nerves [4,5]. The CN nuclei arise in the brainstem, largely topologically arranged between the midbrain and the rostral cervical spine (CN XI). Current knowledge of CN anatomy has been improved by modern microsurgical techniques and endoscopic dissections, allowing visualization of the CN brainstem exit zones [3,4,6-13].

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Cranial Neuropathy

Various nomenclatures for the segments of the CNs are described in the anatomical, surgical, and radiological literature [5,14,15]. In approaching cranial neuropathy, several concepts should be emphasized: 1. Cranial neuropathy can result from pathology affecting the nerve fibers at any point from the CN nucleus to the end organ supplied by the nerve. Pathologic processes affecting the brain, CN nuclei, or nerve fiber tracts supplying CNs are often associated with multiple neurologic symptoms. The CNs may take long, circuitous routes to their end organs. A detailed knowledge of CN anatomy coupled with a careful neurologic examination is essential for proper clinical localization of potential lesions and for the selection of appropriate imaging protocols. aMayo Clinic Arizona, Phoenix, Arizona. bPanel Chair, University of Iowa Hospitals and Clinics, Iowa City, Iowa. cPanel Vice-Chair, Massachusetts Eye and Ear, Harvard Medical School, Boston, Massachusetts. dFroedtert Memorial Lutheran Hospital Medical College of Wisconsin, Milwaukee, Wisconsin. eStritch School of Medicine Loyola University Chicago, Maywood, Illinois. fMontefiore Medical Center, Bronx, New York. gNorthwestern University Feinberg School of Medicine, Chicago, Illinois; American Academy of Otolaryngology-Head and Neck Surgery. hRush University Medical Center, Chicago, Illinois; Neurosurgery expert. iHouston Methodist Hospital, Houston, Texas. jUniversity of Texas Health Science Center, Houston, Texas. kThe University of Texas MD Anderson Cancer Center, Houston, Texas. lNew York University Langone Medical Center, New York, New York. mMayo Clinic, Rochester, Minnesota. nMetroHealth Medical Center, Cleveland, Ohio. oUniversity of North Carolina School of Medicine, Chapel Hill, North Carolina; American Academy of Neurology. pNorthwestern University Feinberg School of Medicine, Chicago, Illinois; Neurosurgery expert. qGeorge Washington University Hospital, Washington, District of Columbia.

Cranial Neuropathy. Various nomenclatures for the segments of the CNs are described in the anatomical, surgical, and radiological literature [5,14,15]. In approaching cranial neuropathy, several concepts should be emphasized: 1. Cranial neuropathy can result from pathology affecting the nerve fibers at any point from the CN nucleus to the end organ supplied by the nerve. Pathologic processes affecting the brain, CN nuclei, or nerve fiber tracts supplying CNs are often associated with multiple neurologic symptoms. The CNs may take long, circuitous routes to their end organs. A detailed knowledge of CN anatomy coupled with a careful neurologic examination is essential for proper clinical localization of potential lesions and for the selection of appropriate imaging protocols. aMayo Clinic Arizona, Phoenix, Arizona. bPanel Chair, University of Iowa Hospitals and Clinics, Iowa City, Iowa. cPanel Vice-Chair, Massachusetts Eye and Ear, Harvard Medical School, Boston, Massachusetts. dFroedtert Memorial Lutheran Hospital Medical College of Wisconsin, Milwaukee, Wisconsin. eStritch School of Medicine Loyola University Chicago, Maywood, Illinois. fMontefiore Medical Center, Bronx, New York. gNorthwestern University Feinberg School of Medicine, Chicago, Illinois; American Academy of Otolaryngology-Head and Neck Surgery. hRush University Medical Center, Chicago, Illinois; Neurosurgery expert. iHouston Methodist Hospital, Houston, Texas. jUniversity of Texas Health Science Center, Houston, Texas. kThe University of Texas MD Anderson Cancer Center, Houston, Texas. lNew York University Langone Medical Center, New York, New York. mMayo Clinic, Rochester, Minnesota. nMetroHealth Medical Center, Cleveland, Ohio. oUniversity of North Carolina School of Medicine, Chapel Hill, North Carolina; American Academy of Neurology. pNorthwestern University Feinberg School of Medicine, Chicago, Illinois; Neurosurgery expert. qGeorge Washington University Hospital, Washington, District of Columbia.

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Cranial Neuropathy

rUniversity of Iowa Hospital, Iowa City, Iowa, Primary care physician. sUniversity of Colorado Denver, Denver, Colorado. tSpecialty 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. Reprint requests to: [email protected] Cranial Neuropathy Special Imaging Considerations MRI is the standard modality for imaging the CNs. Imaging with 3.0T is preferred over 1.5T imaging because of superior signal-to-noise ratios, gradient strength, and spatial resolution, although diagnostic information can be obtained with 1.5T imaging when 3.0T imaging is not available or precluded [5]. A phased-array head coil suffices for most examinations; specialized surface coils may supplement examinations of peripherally located nerves [5,19,20]. Fundamental techniques include thin-cut T1-weighted, T2-weighted, and contrast-enhanced T1-weighted sequences. The unenhanced T1-weighted sequence remains an excellent baseline technique for anatomic evaluation because of the natural contrast provided by fat in the neck and skull base. Diffusion-weighted imaging (DWI) is useful to assess for acute infarctions, cellular tumors, or specific lesions that may affect CN function, such as epidermoids or cholesteatomas. Thin section nonecho planar DWI with decreased susceptibility artifact compared with echo planar DWI allows for increased sensitivity in detection of small cholesteatomas. The use of intravenous (IV) contrast is imperative for the evaluation of cranial neuropathy with MRI. Neck CT also requires the use of IV contrast when evaluating for lesions in the neck causing cranial neuropathy.

Cranial Neuropathy. rUniversity of Iowa Hospital, Iowa City, Iowa, Primary care physician. sUniversity of Colorado Denver, Denver, Colorado. tSpecialty 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. Reprint requests to: [email protected] Cranial Neuropathy Special Imaging Considerations MRI is the standard modality for imaging the CNs. Imaging with 3.0T is preferred over 1.5T imaging because of superior signal-to-noise ratios, gradient strength, and spatial resolution, although diagnostic information can be obtained with 1.5T imaging when 3.0T imaging is not available or precluded [5]. A phased-array head coil suffices for most examinations; specialized surface coils may supplement examinations of peripherally located nerves [5,19,20]. Fundamental techniques include thin-cut T1-weighted, T2-weighted, and contrast-enhanced T1-weighted sequences. The unenhanced T1-weighted sequence remains an excellent baseline technique for anatomic evaluation because of the natural contrast provided by fat in the neck and skull base. Diffusion-weighted imaging (DWI) is useful to assess for acute infarctions, cellular tumors, or specific lesions that may affect CN function, such as epidermoids or cholesteatomas. Thin section nonecho planar DWI with decreased susceptibility artifact compared with echo planar DWI allows for increased sensitivity in detection of small cholesteatomas. The use of intravenous (IV) contrast is imperative for the evaluation of cranial neuropathy with MRI. Neck CT also requires the use of IV contrast when evaluating for lesions in the neck causing cranial neuropathy.

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Cranial Neuropathy

Thin-section imaging with high-spatial resolution is required to directly image the CNs or their course. Slice thickness should be calculated for optimal spatial resolution without introducing partial-volume effect. The primary plane of imaging varies with the CN of interest and should include orthogonal views. The CN nuclei and fascicular nerve segments (brainstem segments) are not well seen on MRI, but their location can be deduced by recognizing surrounding anatomy and are best imaged with various T2-weighted, multi-echo, and fluid-attenuated inversion- recovery (FLAIR) sequences [15]. Three-dimensional isotropic heavily T2-weighted sequences with low CSF artifact provide submillimeter high-spatial and contrast resolution to image the cisternal and dural cave segments of the CNs and can be reformatted into multiple planes [5,21-23]. Intradural and foraminal CN segments, surrounded by a vascular plexus, are best imaged with contrast-enhanced 2- D or 3-D T1-weighted images, contrast-enhanced MR angiography (MRA) or contrast-enhanced modified balanced steady-state free precession (SSFP) sequences in which the nerves appear dark while surrounded by the vascular plexus [5,15,23,24]. The peripheral or extraforaminal segments of the CNs begin as they exit the skull base where they are initially surrounded by fat and are well imaged with high-resolution axial and coronal T1-weighted and T2-weighted sequences and with SSFP sequences as they course within the face and neck [5,15]. Contrast-enhanced fat-suppressed T1-weighted techniques may emphasize abnormal nerves or lesions but can mask subtle pathology if the fat-suppression is nonuniform. Because CN examinations tend to be lengthy, strategies such as parallel imaging may improve patient compliance and image quality [15]. DWI and fiber tract imaging techniques have shown some improvement in visualization of CN fascicles and fiber tracts but are without sufficient reliability for routine clinical use [5,25,26].

Cranial Neuropathy. Thin-section imaging with high-spatial resolution is required to directly image the CNs or their course. Slice thickness should be calculated for optimal spatial resolution without introducing partial-volume effect. The primary plane of imaging varies with the CN of interest and should include orthogonal views. The CN nuclei and fascicular nerve segments (brainstem segments) are not well seen on MRI, but their location can be deduced by recognizing surrounding anatomy and are best imaged with various T2-weighted, multi-echo, and fluid-attenuated inversion- recovery (FLAIR) sequences [15]. Three-dimensional isotropic heavily T2-weighted sequences with low CSF artifact provide submillimeter high-spatial and contrast resolution to image the cisternal and dural cave segments of the CNs and can be reformatted into multiple planes [5,21-23]. Intradural and foraminal CN segments, surrounded by a vascular plexus, are best imaged with contrast-enhanced 2- D or 3-D T1-weighted images, contrast-enhanced MR angiography (MRA) or contrast-enhanced modified balanced steady-state free precession (SSFP) sequences in which the nerves appear dark while surrounded by the vascular plexus [5,15,23,24]. The peripheral or extraforaminal segments of the CNs begin as they exit the skull base where they are initially surrounded by fat and are well imaged with high-resolution axial and coronal T1-weighted and T2-weighted sequences and with SSFP sequences as they course within the face and neck [5,15]. Contrast-enhanced fat-suppressed T1-weighted techniques may emphasize abnormal nerves or lesions but can mask subtle pathology if the fat-suppression is nonuniform. Because CN examinations tend to be lengthy, strategies such as parallel imaging may improve patient compliance and image quality [15]. DWI and fiber tract imaging techniques have shown some improvement in visualization of CN fascicles and fiber tracts but are without sufficient reliability for routine clinical use [5,25,26].

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Cranial Neuropathy

In the setting of cranial neuropathy, thin-cut high-resolution CT can be complementary to MRI in characterizing the osseous integrity of the skull base and skull base foramina. Knowledge of CN anatomy coupled with a careful neurologic examination can aid in tailoring imaging protocols, particularly if a central or peripheral CN palsy can be distinguished clinically. If the probable location of the causative lesion cannot be deduced clinically, imaging of the entire course of the relevant CN may be required because cranial neuropathy can result from pathology affecting the nerve fibers at any point along the course of the nerve and might require multiple imaging modalities. For example, complete evaluation of CN VII includes imaging of the parotid gland and face, because causative lesions can be intraparotid or cutaneous. Head and neck imaging is required to completely image the courses of CN IX, CN XI, and CN XII, which extend into the neck to innervate Cranial Neuropathy end organs. Evaluation of the head, neck, and upper chest is necessary for complete evaluation of the CN X to include the recurrent laryngeal nerve. This can be accomplished by extending the neck scan into the mid thorax (aortic pulmonary window) or by adding a dedicated chest CT. Patients presenting with otalgia may require evaluation of CN V, VII, IX, and X and upper cervical nerves C2 and C3 because any of these nerves may be the source for the otalgia [27]. Most patients with olfactory symptoms do not require imaging, unless history or physical examination warrants it [29]. Causative factors for olfactory impairment can be categorized into three main groups, including conduction loss from sinonasal passage obstruction, sensorineural loss from olfactory neuroepithelial damage, and dysfunction from central nervous system disorders [30,31]. Trauma, aging, upper respiratory infections, and inflammatory sinonasal disorders most commonly affect the sense of smell [30-32].

Cranial Neuropathy. In the setting of cranial neuropathy, thin-cut high-resolution CT can be complementary to MRI in characterizing the osseous integrity of the skull base and skull base foramina. Knowledge of CN anatomy coupled with a careful neurologic examination can aid in tailoring imaging protocols, particularly if a central or peripheral CN palsy can be distinguished clinically. If the probable location of the causative lesion cannot be deduced clinically, imaging of the entire course of the relevant CN may be required because cranial neuropathy can result from pathology affecting the nerve fibers at any point along the course of the nerve and might require multiple imaging modalities. For example, complete evaluation of CN VII includes imaging of the parotid gland and face, because causative lesions can be intraparotid or cutaneous. Head and neck imaging is required to completely image the courses of CN IX, CN XI, and CN XII, which extend into the neck to innervate Cranial Neuropathy end organs. Evaluation of the head, neck, and upper chest is necessary for complete evaluation of the CN X to include the recurrent laryngeal nerve. This can be accomplished by extending the neck scan into the mid thorax (aortic pulmonary window) or by adding a dedicated chest CT. Patients presenting with otalgia may require evaluation of CN V, VII, IX, and X and upper cervical nerves C2 and C3 because any of these nerves may be the source for the otalgia [27]. Most patients with olfactory symptoms do not require imaging, unless history or physical examination warrants it [29]. Causative factors for olfactory impairment can be categorized into three main groups, including conduction loss from sinonasal passage obstruction, sensorineural loss from olfactory neuroepithelial damage, and dysfunction from central nervous system disorders [30,31]. Trauma, aging, upper respiratory infections, and inflammatory sinonasal disorders most commonly affect the sense of smell [30-32].

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Cranial Neuropathy

Tumors affecting the cribriform plate such as squamous cell carcinomas, meningiomas, and esthesioneuroblastoma or olfactory neuroblastomas; inflammatory lesions such as sarcoidosis and granulomatosis with polyangiitis; and congenital conditions such as cephaloceles and Kallmann syndrome can also result in impaired olfaction [32-34]. Olfactory dysfunction is also associated with neurodegenerative, cognitive, and mood disorders including Alzheimer disease, Parkinson disease, and depression [30,35-38]. CT Head There is no relevant literature to support the use of CT head in the evaluation of the olfactory nerve. CT Maxillofacial CT of the paranasal sinuses and face is useful to evaluate fractures, paranasal sinus inflammatory disease, and bony anatomy that impact olfaction [29,39-41]. CT can be used to characterize sinonasal inflammatory disease. Rhinosinusitis with nasal polyposis severity, as characterized by CT, correlates with worse olfaction [31]. Although the anatomic subunits of the olfactory pathway except for the olfactory bulbs cannot be directly visualized by CT, imaging protocols should cover the major anatomic divisions of the olfactory nerve and pathway, including the olfactory epithelium, which is located in the upper nasal cavity; the olfactory neurons and bulbs, located in the cribriform plate and inferior frontal lobes; and the olfactory pathways, which travel in portions of the temporal and Cranial Neuropathy frontal lobes [4]. No IV contrast is necessary for osseous evaluation including posttrauma and for uncomplicated inflammatory sinonasal disease. Contrast-enhanced CT is useful to evaluate granulomatous and neoplastic disease. There is no relevant literature to support the use of combined pre- and postcontrast imaging. CTA Head There is no relevant literature to support the use of CT angiography (CTA) head in the evaluation of the olfactory nerve.

Cranial Neuropathy. Tumors affecting the cribriform plate such as squamous cell carcinomas, meningiomas, and esthesioneuroblastoma or olfactory neuroblastomas; inflammatory lesions such as sarcoidosis and granulomatosis with polyangiitis; and congenital conditions such as cephaloceles and Kallmann syndrome can also result in impaired olfaction [32-34]. Olfactory dysfunction is also associated with neurodegenerative, cognitive, and mood disorders including Alzheimer disease, Parkinson disease, and depression [30,35-38]. CT Head There is no relevant literature to support the use of CT head in the evaluation of the olfactory nerve. CT Maxillofacial CT of the paranasal sinuses and face is useful to evaluate fractures, paranasal sinus inflammatory disease, and bony anatomy that impact olfaction [29,39-41]. CT can be used to characterize sinonasal inflammatory disease. Rhinosinusitis with nasal polyposis severity, as characterized by CT, correlates with worse olfaction [31]. Although the anatomic subunits of the olfactory pathway except for the olfactory bulbs cannot be directly visualized by CT, imaging protocols should cover the major anatomic divisions of the olfactory nerve and pathway, including the olfactory epithelium, which is located in the upper nasal cavity; the olfactory neurons and bulbs, located in the cribriform plate and inferior frontal lobes; and the olfactory pathways, which travel in portions of the temporal and Cranial Neuropathy frontal lobes [4]. No IV contrast is necessary for osseous evaluation including posttrauma and for uncomplicated inflammatory sinonasal disease. Contrast-enhanced CT is useful to evaluate granulomatous and neoplastic disease. There is no relevant literature to support the use of combined pre- and postcontrast imaging. CTA Head There is no relevant literature to support the use of CT angiography (CTA) head in the evaluation of the olfactory nerve.

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Cranial Neuropathy

FDG-PET/CT Efforts using functional MRI, single-photon emission CT, and fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG)-PET in studying olfactory dysfunction and the role of olfaction in neurodegenerative disorders remain largely investigative and are not generally used in routine evaluations [42-48]. MRA Head There is no relevant literature to support the use of MRA head in the evaluation of the olfactory nerve. MRI Head MRI is the mainstay for directly imaging the olfactory apparatus and is best assessed with MRI orbits, face, and neck MRI rather than MRI head, allowing for assessment of the sinonasal components of the olfactory apparatus while simultaneously evaluating the relevant brain structures that can affect olfaction. US Neck There is no relevant literature to support the use of ultrasound (US) neck in the evaluation of the olfactory nerve. Variant 2: Unilateral isolated weakness of the mastication muscles, paralysis of the mastication muscles, sensory abnormalities of the face and head, facial numbness, or trigeminal neuralgia (trigeminal nerve, CN V). Initial imaging. The trigeminal nerve (CN V) is the largest CN, providing general sensation to the face, part of the scalp, the nasal cavity, oral cavity, and teeth. It also provides branchial motor innervation to the muscles of mastication. The 4 central trigeminal nerve nuclei are located within the brainstem and include the mesencephalic nucleus, the principal sensory nucleus, the motor nucleus, and the spinal trigeminal tract and nucleus. The spinal trigeminal tract and nucleus extend from the midpons caudally into the upper cervical cord at the C2-C4 levels. The trigeminal nerve is divided into 3 main divisions, known as the ophthalmic (V1), maxillary (V2), and mandibular (V3) branches [3]. Symptoms of trigeminal neuropathy or neuropathic pain syndromes vary with the involved segment and division and may or may not include other sensory deficits (such as facial numbness) or motor deficits (such as weakness with mastication).

Cranial Neuropathy. FDG-PET/CT Efforts using functional MRI, single-photon emission CT, and fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG)-PET in studying olfactory dysfunction and the role of olfaction in neurodegenerative disorders remain largely investigative and are not generally used in routine evaluations [42-48]. MRA Head There is no relevant literature to support the use of MRA head in the evaluation of the olfactory nerve. MRI Head MRI is the mainstay for directly imaging the olfactory apparatus and is best assessed with MRI orbits, face, and neck MRI rather than MRI head, allowing for assessment of the sinonasal components of the olfactory apparatus while simultaneously evaluating the relevant brain structures that can affect olfaction. US Neck There is no relevant literature to support the use of ultrasound (US) neck in the evaluation of the olfactory nerve. Variant 2: Unilateral isolated weakness of the mastication muscles, paralysis of the mastication muscles, sensory abnormalities of the face and head, facial numbness, or trigeminal neuralgia (trigeminal nerve, CN V). Initial imaging. The trigeminal nerve (CN V) is the largest CN, providing general sensation to the face, part of the scalp, the nasal cavity, oral cavity, and teeth. It also provides branchial motor innervation to the muscles of mastication. The 4 central trigeminal nerve nuclei are located within the brainstem and include the mesencephalic nucleus, the principal sensory nucleus, the motor nucleus, and the spinal trigeminal tract and nucleus. The spinal trigeminal tract and nucleus extend from the midpons caudally into the upper cervical cord at the C2-C4 levels. The trigeminal nerve is divided into 3 main divisions, known as the ophthalmic (V1), maxillary (V2), and mandibular (V3) branches [3]. Symptoms of trigeminal neuropathy or neuropathic pain syndromes vary with the involved segment and division and may or may not include other sensory deficits (such as facial numbness) or motor deficits (such as weakness with mastication).

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Cranial Neuropathy

In patients with clinical features of trigeminal neuropathy, initial imaging is performed along the entire course of the trigeminal nerve to evaluate for a causative lesion [57]. The trigeminal nerve can be affected by processes anywhere along its course from the brainstem to its peripheral branches; consequently, imaging should cover the entire course of the nerve. Brainstem lesions can affect the trigeminal nerve but rarely lead to isolated trigeminal neuropathy because of the close proximity of neural structures within the brainstem. In particular, multiple sclerosis can result in trigeminal neuralgia, necessitating imaging of the brainstem to look for demyelinating disease [58-61]. Other brainstem lesions that can affect the trigeminal nerve include infarction, hemorrhage, vascular lesions (such as compressing vascular loops, aneurysms, and Cranial Neuropathy vertebrobasilar dolichoectasia), inflammatory and infectious conditions (such as meningitis, encephalitis, sarcoidosis, and demyelinating disease), and tumors (such as gliomas, lymphomas, and metastases) [59]. Tumors, vascular lesions, and inflammatory processes may also affect the cisternal, dural cave, cavernous, foraminal, and extracranial branches of the nerve as they traverse the Meckel cave, the pterygopalatine fossa, the orbit, the skull base, and the masticator space [59,62,63]. Perineural spread of tumor, discussed in Variant 10, can affect the trigeminal nerve anywhere along its course. CT Head CT is a complementary study for evaluating the osseous integrity of the skull base and neural foramina. However, standard coverage with a CT Head is insufficient to evaluate the full extent of the trigeminal nerve divisions in the face. There is no relevant literature to support the use of combined pre- and postcontrast imaging. CT Maxillofacial Maxillofacial CT is a complementary study for evaluating the osseous integrity of the skull base and neural foramina, which can be accomplished without IV contrast.

Cranial Neuropathy. In patients with clinical features of trigeminal neuropathy, initial imaging is performed along the entire course of the trigeminal nerve to evaluate for a causative lesion [57]. The trigeminal nerve can be affected by processes anywhere along its course from the brainstem to its peripheral branches; consequently, imaging should cover the entire course of the nerve. Brainstem lesions can affect the trigeminal nerve but rarely lead to isolated trigeminal neuropathy because of the close proximity of neural structures within the brainstem. In particular, multiple sclerosis can result in trigeminal neuralgia, necessitating imaging of the brainstem to look for demyelinating disease [58-61]. Other brainstem lesions that can affect the trigeminal nerve include infarction, hemorrhage, vascular lesions (such as compressing vascular loops, aneurysms, and Cranial Neuropathy vertebrobasilar dolichoectasia), inflammatory and infectious conditions (such as meningitis, encephalitis, sarcoidosis, and demyelinating disease), and tumors (such as gliomas, lymphomas, and metastases) [59]. Tumors, vascular lesions, and inflammatory processes may also affect the cisternal, dural cave, cavernous, foraminal, and extracranial branches of the nerve as they traverse the Meckel cave, the pterygopalatine fossa, the orbit, the skull base, and the masticator space [59,62,63]. Perineural spread of tumor, discussed in Variant 10, can affect the trigeminal nerve anywhere along its course. CT Head CT is a complementary study for evaluating the osseous integrity of the skull base and neural foramina. However, standard coverage with a CT Head is insufficient to evaluate the full extent of the trigeminal nerve divisions in the face. There is no relevant literature to support the use of combined pre- and postcontrast imaging. CT Maxillofacial Maxillofacial CT is a complementary study for evaluating the osseous integrity of the skull base and neural foramina, which can be accomplished without IV contrast.

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Cranial Neuropathy

CT may be helpful for visualizing perineural fat planes, which can be distorted or obliterated in patients with lesions affecting the trigeminal nerve, although MRI offers improved detection of perineural tumor spread (discussed in Variant 10) compared with CT, which has a sensitivity and specificity of 88% and 89%, respectively [64-66]. CT with IV contrast offers the benefits of vascular and mucosal enhancement and may highlight enhancing lesions. There is no relevant literature to support the use of combined pre- and postcontrast imaging. Thin section contrast-enhanced navigation protocol CT is useful for noninvasive treatment planning in patients with known trigeminal neuralgia [67]. CTA Head There is no relevant literature to support the use of CTA head in the initial evaluation of trigeminal neuropathy. In patients with clinical features of trigeminal neuralgia, high-resolution combined MRI, MRA, and CTA may be used to assess for vascular loops compressing the fifth nerve. Anatomic and dedicated vascular imaging play a complementary role. Structural MRI evaluation of the nerve and its relationship to vasculature is more commonly reported in the literature, likely related to the improved soft tissue contrast of MRI compared with CT [23,68-76]. CTA has been used to characterize the relationship of arterial vasculature relative to the fifth nerve in patients with a clinical diagnosis of trigeminal neuralgia but is less commonly used than MRI and MRA because it does not provide simultaneous high-resolution imaging of the trigeminal nerve provided by MRI [77]. MRA Head There is no relevant literature to support the use of MRA head in the initial evaluation of trigeminal neuropathy.

Cranial Neuropathy. CT may be helpful for visualizing perineural fat planes, which can be distorted or obliterated in patients with lesions affecting the trigeminal nerve, although MRI offers improved detection of perineural tumor spread (discussed in Variant 10) compared with CT, which has a sensitivity and specificity of 88% and 89%, respectively [64-66]. CT with IV contrast offers the benefits of vascular and mucosal enhancement and may highlight enhancing lesions. There is no relevant literature to support the use of combined pre- and postcontrast imaging. Thin section contrast-enhanced navigation protocol CT is useful for noninvasive treatment planning in patients with known trigeminal neuralgia [67]. CTA Head There is no relevant literature to support the use of CTA head in the initial evaluation of trigeminal neuropathy. In patients with clinical features of trigeminal neuralgia, high-resolution combined MRI, MRA, and CTA may be used to assess for vascular loops compressing the fifth nerve. Anatomic and dedicated vascular imaging play a complementary role. Structural MRI evaluation of the nerve and its relationship to vasculature is more commonly reported in the literature, likely related to the improved soft tissue contrast of MRI compared with CT [23,68-76]. CTA has been used to characterize the relationship of arterial vasculature relative to the fifth nerve in patients with a clinical diagnosis of trigeminal neuralgia but is less commonly used than MRI and MRA because it does not provide simultaneous high-resolution imaging of the trigeminal nerve provided by MRI [77]. MRA Head There is no relevant literature to support the use of MRA head in the initial evaluation of trigeminal neuropathy.

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Cranial Neuropathy

In patients with clinical features of trigeminal neuralgia, MRA is commonly used as a complementary study to high- resolution MRI in assessing for vascular compression of the CN V with sensitivities of combined MRI with MRA ranging from 97% to 100%, specificities reported as 100%, and good to strong agreement found compared with surgical findings [69,71-73,76]. One group reported a lower sensitivity (50% at 3T and 33% at 1.5T) of combined high-resolution MRI with MRA for detection of neurovascular compression of CN V by smaller vessels such as the anterior inferior cerebellar artery [71]. Cranial Neuropathy In patients with clinical features of trigeminal neuralgia, 3-D heavily T2-weighted MRI sequences, MRA, and a combination of these techniques are commonly used noninvasive methods for characterizing the anatomy of vascular loops potentially compressing the fifth nerve and correlate well with surgical findings [23,68-76]. Congruence rates of imaging and intraoperative findings for neurovascular contact range from 83% to 100% [68- 70,72,75,78]. Both false-positive and false-negative imaging studies occur when assessing for neurovascular contact in the setting of trigeminal neuralgia; consequently, MRI is supportive rather than diagnostic in selecting candidates for microvascular decompression and should be interpreted in the context of the site of symptoms [69,73-75,78]. Imaging evidence of vascular trigeminal nerve root compression, the degree of compression, location of contact, and nerve volume may have prognostic value [73,77,79-81]. Trigeminal nerve size measurements have been reported as smaller on the symptomatic side in trigeminal neuralgia as measured from thin-cut MRI [82-84]. Preoperative imaging is useful for surgical planning [85]. Advanced MRI techniques including diffusion tensor imaging (DTI), functional MRI, and voxel-based morphometry are being used to research the pathophysiology of trigeminal neuralgia.

Cranial Neuropathy. In patients with clinical features of trigeminal neuralgia, MRA is commonly used as a complementary study to high- resolution MRI in assessing for vascular compression of the CN V with sensitivities of combined MRI with MRA ranging from 97% to 100%, specificities reported as 100%, and good to strong agreement found compared with surgical findings [69,71-73,76]. One group reported a lower sensitivity (50% at 3T and 33% at 1.5T) of combined high-resolution MRI with MRA for detection of neurovascular compression of CN V by smaller vessels such as the anterior inferior cerebellar artery [71]. Cranial Neuropathy In patients with clinical features of trigeminal neuralgia, 3-D heavily T2-weighted MRI sequences, MRA, and a combination of these techniques are commonly used noninvasive methods for characterizing the anatomy of vascular loops potentially compressing the fifth nerve and correlate well with surgical findings [23,68-76]. Congruence rates of imaging and intraoperative findings for neurovascular contact range from 83% to 100% [68- 70,72,75,78]. Both false-positive and false-negative imaging studies occur when assessing for neurovascular contact in the setting of trigeminal neuralgia; consequently, MRI is supportive rather than diagnostic in selecting candidates for microvascular decompression and should be interpreted in the context of the site of symptoms [69,73-75,78]. Imaging evidence of vascular trigeminal nerve root compression, the degree of compression, location of contact, and nerve volume may have prognostic value [73,77,79-81]. Trigeminal nerve size measurements have been reported as smaller on the symptomatic side in trigeminal neuralgia as measured from thin-cut MRI [82-84]. Preoperative imaging is useful for surgical planning [85]. Advanced MRI techniques including diffusion tensor imaging (DTI), functional MRI, and voxel-based morphometry are being used to research the pathophysiology of trigeminal neuralgia.

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acrac_69509_10

Cranial Neuropathy

DTI metrics suggest microstructural tissue changes in symptomatic nerves in the setting of trigeminal neuralgia compared with asymptomatic nerves and may be useful for making treatment decisions [68,86-93]. Advanced MRI techniques have also detected structural alterations in gray matter and white matter in patients with trigeminal neuralgia [94-97]. MR neurography is an emerging technique that may be useful in characterizing the etiology of peripheral trigeminal neuropathy [98]. In patients with clinical features of trigeminal neuralgia, 3-D heavily T2-weighted MRI sequences, MRA, and a combination of these techniques are commonly used noninvasive methods for characterizing the anatomy of vascular loops potentially compressing the cisternal segment of the fifth nerve and correlate well with surgical findings [23,68-76]. Congruence rates of imaging and intraoperative findings for neurovascular contact range from 83% to 100% [68-70,72,75,78]. Both false-positive and false-negative imaging studies occur when assessing for neurovascular contact in the setting of trigeminal neuralgia; consequently, MRI is supportive rather than diagnostic in selecting candidates for microvascular decompression and should be interpreted in the context of the site of symptoms [69,73-75,78]. Imaging evidence of vascular trigeminal nerve root compression, the degree of compression, location of contact, and nerve volume may have prognostic value [73,77,79-81]. Trigeminal nerve size measurements have been reported as smaller on the symptomatic side in trigeminal neuralgia as measured from thin-cut MRI [82-84]. Preoperative imaging is useful for surgical planning [85]. Advanced MRI techniques including DTI, functional MRI, and voxel-based morphometry are being used to research the pathophysiology of trigeminal neuralgia.

Cranial Neuropathy. DTI metrics suggest microstructural tissue changes in symptomatic nerves in the setting of trigeminal neuralgia compared with asymptomatic nerves and may be useful for making treatment decisions [68,86-93]. Advanced MRI techniques have also detected structural alterations in gray matter and white matter in patients with trigeminal neuralgia [94-97]. MR neurography is an emerging technique that may be useful in characterizing the etiology of peripheral trigeminal neuropathy [98]. In patients with clinical features of trigeminal neuralgia, 3-D heavily T2-weighted MRI sequences, MRA, and a combination of these techniques are commonly used noninvasive methods for characterizing the anatomy of vascular loops potentially compressing the cisternal segment of the fifth nerve and correlate well with surgical findings [23,68-76]. Congruence rates of imaging and intraoperative findings for neurovascular contact range from 83% to 100% [68-70,72,75,78]. Both false-positive and false-negative imaging studies occur when assessing for neurovascular contact in the setting of trigeminal neuralgia; consequently, MRI is supportive rather than diagnostic in selecting candidates for microvascular decompression and should be interpreted in the context of the site of symptoms [69,73-75,78]. Imaging evidence of vascular trigeminal nerve root compression, the degree of compression, location of contact, and nerve volume may have prognostic value [73,77,79-81]. Trigeminal nerve size measurements have been reported as smaller on the symptomatic side in trigeminal neuralgia as measured from thin-cut MRI [82-84]. Preoperative imaging is useful for surgical planning [85]. Advanced MRI techniques including DTI, functional MRI, and voxel-based morphometry are being used to research the pathophysiology of trigeminal neuralgia.

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acrac_69509_11

Cranial Neuropathy

DTI metrics suggest microstructural tissue changes in symptomatic nerves in the setting of trigeminal neuralgia compared with asymptomatic nerves and may be useful for making treatment decisions [68,86-93]. Advanced MRI techniques have also detected structural alterations in gray matter and white matter in patients with trigeminal neuralgia [94-97]. MR neurography is an emerging technique that may be useful in characterizing the etiology of peripheral trigeminal neuropathy [98]. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of FDG-PET/CT skull base to mid-thigh in the evaluation of isolated trigeminal mononeuropathy or isolated unilateral trigeminal neuralgia. US Neck There is no relevant literature to support the use of US neck in the evaluation of isolated trigeminal mononeuropathy or isolated unilateral trigeminal neuralgia. Cranial Neuropathy Variant 3: Unilateral isolated weakness of the facial expression, paralysis of the facial expression, hemifacial spasm, or Bell palsy (facial nerve, CN VII). Initial imaging. The facial nerve (CN VII) is one of the most complex CNs and contains branchial motor (innervation to the muscles of facial expression), visceral motor (parasympathetic innervation to most of the glands of the head), general sensory (surface innervations to a small portion of the external ear and tympanic membrane), and special sensory (taste to the anterior two-thirds of the tongue) functions [2,99]. From its nucleus in the pons, the intraparenchymal fascicular or attached segment courses superiorly along the surface of the pons after which it turns anteriorly exiting the brainstem at the pontomedullary sulcus, which is referred to as the root exit point. Its parenchymal fascicular or attached segment courses superiorly along the surface of the pons after which it turns anteriorly, detaching from the pons at the root detachment point [5,100,101].

Cranial Neuropathy. DTI metrics suggest microstructural tissue changes in symptomatic nerves in the setting of trigeminal neuralgia compared with asymptomatic nerves and may be useful for making treatment decisions [68,86-93]. Advanced MRI techniques have also detected structural alterations in gray matter and white matter in patients with trigeminal neuralgia [94-97]. MR neurography is an emerging technique that may be useful in characterizing the etiology of peripheral trigeminal neuropathy [98]. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of FDG-PET/CT skull base to mid-thigh in the evaluation of isolated trigeminal mononeuropathy or isolated unilateral trigeminal neuralgia. US Neck There is no relevant literature to support the use of US neck in the evaluation of isolated trigeminal mononeuropathy or isolated unilateral trigeminal neuralgia. Cranial Neuropathy Variant 3: Unilateral isolated weakness of the facial expression, paralysis of the facial expression, hemifacial spasm, or Bell palsy (facial nerve, CN VII). Initial imaging. The facial nerve (CN VII) is one of the most complex CNs and contains branchial motor (innervation to the muscles of facial expression), visceral motor (parasympathetic innervation to most of the glands of the head), general sensory (surface innervations to a small portion of the external ear and tympanic membrane), and special sensory (taste to the anterior two-thirds of the tongue) functions [2,99]. From its nucleus in the pons, the intraparenchymal fascicular or attached segment courses superiorly along the surface of the pons after which it turns anteriorly exiting the brainstem at the pontomedullary sulcus, which is referred to as the root exit point. Its parenchymal fascicular or attached segment courses superiorly along the surface of the pons after which it turns anteriorly, detaching from the pons at the root detachment point [5,100,101].

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Cranial Neuropathy

It then traverses the cerebellopontine angle in its cisternal segment, enters the internal auditory canal within its meatal segment, and courses through the temporal bone (which includes the labyrinthine, tympanic, mastoid segments, and geniculate ganglion). The facial nerve exits the temporal bone at the stylomastoid foramen, and the extracranial segment courses through the parotid gland. Peripheral, nuclear, or infranuclear facial nerve paralysis presents as ipsilateral facial paralysis with involvement of the forehead (which is usually spared with a supranuclear facial nerve palsy) and can result from pathology affecting the facial nerve nucleus or any portion of the facial nerve after exiting the brainstem within its intracranial and extracranial segments. Within the pons, the facial nuclei can be affected by intra-axial conditions such as infarction, vascular malformations, tumors, and multiple sclerosis. Brainstem lesions are often accompanied by additional neurologic symptoms that can help localize the lesion clinically [102,103]. Rarely brainstem or cortical infarct can result in an isolated facial nerve palsy [102,103]. As the facial nerve exits the brainstem and courses within the cerebellopontine angle, the internal auditory canal, and through the temporal bone, it may be affected by facial and vestibular schwannomas, meningiomas, vascular lesions, inflammation, cholesteatomas, paragangliomas, epidermoid cysts, trauma, and intrinsic bone tumors. The extracranial facial nerve may be affected by inflammation, parotid tumors, conditions of the neighboring anatomic spaces, and skull base pathology including carcinomas, sarcomas, trauma, and inflammatory disease [99,102]. Perineural spread of a tumor can result in facial nerve palsy and is discussed in Variant 10 [104]. Facial nerve palsy can present with facial droop, pain around the jaw or ear, hyperacusis, tinnitus, reduced taste, and decreased lacrimation or salivation.

Cranial Neuropathy. It then traverses the cerebellopontine angle in its cisternal segment, enters the internal auditory canal within its meatal segment, and courses through the temporal bone (which includes the labyrinthine, tympanic, mastoid segments, and geniculate ganglion). The facial nerve exits the temporal bone at the stylomastoid foramen, and the extracranial segment courses through the parotid gland. Peripheral, nuclear, or infranuclear facial nerve paralysis presents as ipsilateral facial paralysis with involvement of the forehead (which is usually spared with a supranuclear facial nerve palsy) and can result from pathology affecting the facial nerve nucleus or any portion of the facial nerve after exiting the brainstem within its intracranial and extracranial segments. Within the pons, the facial nuclei can be affected by intra-axial conditions such as infarction, vascular malformations, tumors, and multiple sclerosis. Brainstem lesions are often accompanied by additional neurologic symptoms that can help localize the lesion clinically [102,103]. Rarely brainstem or cortical infarct can result in an isolated facial nerve palsy [102,103]. As the facial nerve exits the brainstem and courses within the cerebellopontine angle, the internal auditory canal, and through the temporal bone, it may be affected by facial and vestibular schwannomas, meningiomas, vascular lesions, inflammation, cholesteatomas, paragangliomas, epidermoid cysts, trauma, and intrinsic bone tumors. The extracranial facial nerve may be affected by inflammation, parotid tumors, conditions of the neighboring anatomic spaces, and skull base pathology including carcinomas, sarcomas, trauma, and inflammatory disease [99,102]. Perineural spread of a tumor can result in facial nerve palsy and is discussed in Variant 10 [104]. Facial nerve palsy can present with facial droop, pain around the jaw or ear, hyperacusis, tinnitus, reduced taste, and decreased lacrimation or salivation.

69509

acrac_69509_13

Cranial Neuropathy

Facial paralysis in the form of Bell palsy is the most common cause of acute peripheral facial nerve palsy, attributed to inflammation of the facial nerve, which may be idiopathic or due to herpes simplex virus. Most patients experience complete recovery of function by 6 months, which can be hastened with steroids [102]. In general, Bell palsy patients need not be imaged unless the symptoms are atypical, recurrent, or persist for 2 to 4 months [102]. Unilateral hyperactivity of the facial nerve can occur, resulting in the spasm of the facial musculature referred to as hemifacial spasm. Hemifacial spasm is most commonly the result of vascular compression of the facial nerve, usually within the centrally (oligodendrocyte) myelinated portion of the nerve [100]. CT Head There is no relevant literature to support the use of routine CT head alone in the evaluation of unilateral isolated facial nerve palsy. CT Temporal Bone High-resolution thin-cut temporal bone CT provides complementary useful information to MRI by characterizing the osseous integrity of the temporal bone through which the facial nerve courses. CT imaging excels at osseous imaging and characterizes well temporal bone fractures, presurgical osseous anatomy, bony facial nerve canal involvement with inflammatory middle ear disease, facial canal foraminal expansion, patterns of bone erosion, and intrinsic bone tumor matrices [2,99,105-108]. High-resolution temporal bone CT with thin sections should be obtained to evaluate the course of CN VII. Contrast may be useful in the setting of infection or when a tumor is suspected. There is no relevant literature to support the use of combined pre- and postcontrast imaging. High-resolution noncontrast CT of the temporal bone is useful to characterize temporal bone fractures including fractures through the facial nerve canal, but sensitivity for nondisplaced fracture has been shown to vary with fracture location and is lowest in the mastoid segment [105,108]. Cranial Neuropathy

Cranial Neuropathy. Facial paralysis in the form of Bell palsy is the most common cause of acute peripheral facial nerve palsy, attributed to inflammation of the facial nerve, which may be idiopathic or due to herpes simplex virus. Most patients experience complete recovery of function by 6 months, which can be hastened with steroids [102]. In general, Bell palsy patients need not be imaged unless the symptoms are atypical, recurrent, or persist for 2 to 4 months [102]. Unilateral hyperactivity of the facial nerve can occur, resulting in the spasm of the facial musculature referred to as hemifacial spasm. Hemifacial spasm is most commonly the result of vascular compression of the facial nerve, usually within the centrally (oligodendrocyte) myelinated portion of the nerve [100]. CT Head There is no relevant literature to support the use of routine CT head alone in the evaluation of unilateral isolated facial nerve palsy. CT Temporal Bone High-resolution thin-cut temporal bone CT provides complementary useful information to MRI by characterizing the osseous integrity of the temporal bone through which the facial nerve courses. CT imaging excels at osseous imaging and characterizes well temporal bone fractures, presurgical osseous anatomy, bony facial nerve canal involvement with inflammatory middle ear disease, facial canal foraminal expansion, patterns of bone erosion, and intrinsic bone tumor matrices [2,99,105-108]. High-resolution temporal bone CT with thin sections should be obtained to evaluate the course of CN VII. Contrast may be useful in the setting of infection or when a tumor is suspected. There is no relevant literature to support the use of combined pre- and postcontrast imaging. High-resolution noncontrast CT of the temporal bone is useful to characterize temporal bone fractures including fractures through the facial nerve canal, but sensitivity for nondisplaced fracture has been shown to vary with fracture location and is lowest in the mastoid segment [105,108]. Cranial Neuropathy

69509

acrac_69509_14

Cranial Neuropathy

CT Maxillofacial Temporal bone CT (complementary to MRI in patients with facial nerve palsy) is the preferred CT study and typically provides better spatial resolution than maxillofacial CT when assessing the fine detailed anatomy of the temporal bone and bony facial nerve canal. Maxillofacial CT provides better spatial resolution than head CT and, depending on institutional protocols, may provide sufficient spatial resolution to be complementary to MRI to characterize the osseous integrity of the temporal bone and assess the extracranial course of the facial nerve although the nerve itself is not directly imaged with CT [2,99,105-108]. Contrast may be useful when infection or a tumor is suspected. There is no relevant literature to support the use of combined pre- and postcontrast imaging. CTA Head There is no relevant literature to support the use of CTA head as an isolated study in the initial evaluation of acute unilateral facial nerve palsy. Rarely brainstem or cortical infarct can result in isolated facial nerve palsy, and if clinically suspected, CTA may be complementary to MRI in this clinical scenario [102,103] to characterize the vasculature. CTA is uncommonly reported as a complementary study to thin-cut high-resolution MRI for characterizing the anatomy of vascular loops potentially compressing the centrally myelinated portion of the facial nerve [109]. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of FDG-PET/CT skull base to mid-thigh in the evaluation of isolated unilateral facial nerve palsy or hemifacial spasm. MRA Head There is no relevant literature to support the use of MRA alone in the initial evaluation of acute unilateral facial nerve palsy. Rarely brainstem or cortical infarct can result in isolated facial nerve palsy, and if clinically suspected, MRA may be complementary to MRI in this clinical scenario [102,103] to characterize the vasculature. MRA may be useful in the assessment of hemifacial spasm.

Cranial Neuropathy. CT Maxillofacial Temporal bone CT (complementary to MRI in patients with facial nerve palsy) is the preferred CT study and typically provides better spatial resolution than maxillofacial CT when assessing the fine detailed anatomy of the temporal bone and bony facial nerve canal. Maxillofacial CT provides better spatial resolution than head CT and, depending on institutional protocols, may provide sufficient spatial resolution to be complementary to MRI to characterize the osseous integrity of the temporal bone and assess the extracranial course of the facial nerve although the nerve itself is not directly imaged with CT [2,99,105-108]. Contrast may be useful when infection or a tumor is suspected. There is no relevant literature to support the use of combined pre- and postcontrast imaging. CTA Head There is no relevant literature to support the use of CTA head as an isolated study in the initial evaluation of acute unilateral facial nerve palsy. Rarely brainstem or cortical infarct can result in isolated facial nerve palsy, and if clinically suspected, CTA may be complementary to MRI in this clinical scenario [102,103] to characterize the vasculature. CTA is uncommonly reported as a complementary study to thin-cut high-resolution MRI for characterizing the anatomy of vascular loops potentially compressing the centrally myelinated portion of the facial nerve [109]. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of FDG-PET/CT skull base to mid-thigh in the evaluation of isolated unilateral facial nerve palsy or hemifacial spasm. MRA Head There is no relevant literature to support the use of MRA alone in the initial evaluation of acute unilateral facial nerve palsy. Rarely brainstem or cortical infarct can result in isolated facial nerve palsy, and if clinically suspected, MRA may be complementary to MRI in this clinical scenario [102,103] to characterize the vasculature. MRA may be useful in the assessment of hemifacial spasm.

69509

acrac_69509_15

Cranial Neuropathy

In patients with clinical features of hemifacial spasm, MRA can be complementary to 3-D heavily T2-weighted MRI sequences for characterizing the anatomy of vascular loops potentially compressing the centrally myelinated portion of the facial nerve with sensitivity and accuracy reported as >95% and a good correlation with surgical findings [76,109,110]. Volumetric and 3T imaging have been reported to provide improved visualization of the facial nerve and its surrounding perineural vascular plexus [7,19,111,113]. In general, Bell palsy patients need not be imaged unless the symptoms are atypical, recurrent, or persist for 2 to 4 months [102]. When imaging is considered, MRI is the method of choice. Variable abnormal enhancement patterns may be seen in the canalicular, labyrinthine, geniculate, tympanic, and mastoid portions of the nerve [106,117-122]. There is a lack of consensus regarding the prognostic value of MRI in Bell palsy [118-121], and MRI is most useful for excluding other causes of facial nerve palsy. High-resolution thin-cut contrast-enhanced MRI is an especially useful method to evaluate for perineural spread of a tumor, which can affect CN VII and is discussed in Variant 10. Sensitivities for MRI detection of perineural spread of a tumor range from 73% to 100% and vary according to the nerve evaluated and timing of imaging relative to tissue sampling [65,104,123-125]. In patients with clinical features of hemifacial spasm, 3-D heavily T2-weighted MRI sequences and MRA are noninvasive methods for characterizing the anatomy of vascular loops potentially compressing the centrally myelinated portion of the facial nerve and correlate well with surgical findings [76,78,100,101,110]. Both false- positive and false-negative imaging studies occur when assessing for neurovascular contact in the setting of hemifacial spasm; consequently MRI is supportive rather than diagnostic in selecting candidates for microvascular Cranial Neuropathy decompression [78,100].

Cranial Neuropathy. In patients with clinical features of hemifacial spasm, MRA can be complementary to 3-D heavily T2-weighted MRI sequences for characterizing the anatomy of vascular loops potentially compressing the centrally myelinated portion of the facial nerve with sensitivity and accuracy reported as >95% and a good correlation with surgical findings [76,109,110]. Volumetric and 3T imaging have been reported to provide improved visualization of the facial nerve and its surrounding perineural vascular plexus [7,19,111,113]. In general, Bell palsy patients need not be imaged unless the symptoms are atypical, recurrent, or persist for 2 to 4 months [102]. When imaging is considered, MRI is the method of choice. Variable abnormal enhancement patterns may be seen in the canalicular, labyrinthine, geniculate, tympanic, and mastoid portions of the nerve [106,117-122]. There is a lack of consensus regarding the prognostic value of MRI in Bell palsy [118-121], and MRI is most useful for excluding other causes of facial nerve palsy. High-resolution thin-cut contrast-enhanced MRI is an especially useful method to evaluate for perineural spread of a tumor, which can affect CN VII and is discussed in Variant 10. Sensitivities for MRI detection of perineural spread of a tumor range from 73% to 100% and vary according to the nerve evaluated and timing of imaging relative to tissue sampling [65,104,123-125]. In patients with clinical features of hemifacial spasm, 3-D heavily T2-weighted MRI sequences and MRA are noninvasive methods for characterizing the anatomy of vascular loops potentially compressing the centrally myelinated portion of the facial nerve and correlate well with surgical findings [76,78,100,101,110]. Both false- positive and false-negative imaging studies occur when assessing for neurovascular contact in the setting of hemifacial spasm; consequently MRI is supportive rather than diagnostic in selecting candidates for microvascular Cranial Neuropathy decompression [78,100].

69509

acrac_69509_16

Cranial Neuropathy

In patients with failed initial microvascular decompression surgery, heavily T2-weighted MRI may be helpful to delineate the cause [101]. DTI is an advanced imaging technique that may be useful in assessing the facial nerve. Several studies suggest that DTI is accurate for the preoperative localization of the cisternal facial nerve to avoid iatrogenic injury in patients with cerebellopontine angle tumors [107,126-128]. Research indicates that DTI may have future use localizing the intraparotid facial nerve and detecting perineural spread of a tumor [129,130]. Volumetric and 3T imaging have been reported to provide improved visualization of the facial nerve and its surrounding perineural vascular plexus [7,19,111,113]. In general, Bell palsy patients do not need to be imaged unless the symptoms are atypical, recurrent, or persistent for 2 to 4 months [102]. When imaging is considered, MRI is the method of choice. Variable abnormal enhancement patterns may be seen in the canalicular, labyrinthine, geniculate, tympanic, and mastoid portions of the nerve [106,117-122]. There is a lack of consensus regarding the prognostic value of MRI in Bell palsy [118-121], and MRI is most useful for excluding other causes of facial nerve palsy. High-resolution thin-cut contrast-enhanced MRI is an especially useful method to evaluate for perineural spread of a tumor, which can affect CN VII and is discussed in Variant 10. Sensitivities for MRI detection of perineural spread of a tumor range from 73% to 100% and vary according to the nerve evaluated and timing of imaging relative to tissue sampling [65,104,123-125]. In patients with clinical features of hemifacial spasm, 3-D heavily T2-weighted MRI sequences and MRA are noninvasive methods for characterizing the anatomy of vascular loops potentially compressing the centrally myelinated portion of the facial nerve and correlate well with surgical findings [76,78,100,101,110].

Cranial Neuropathy. In patients with failed initial microvascular decompression surgery, heavily T2-weighted MRI may be helpful to delineate the cause [101]. DTI is an advanced imaging technique that may be useful in assessing the facial nerve. Several studies suggest that DTI is accurate for the preoperative localization of the cisternal facial nerve to avoid iatrogenic injury in patients with cerebellopontine angle tumors [107,126-128]. Research indicates that DTI may have future use localizing the intraparotid facial nerve and detecting perineural spread of a tumor [129,130]. Volumetric and 3T imaging have been reported to provide improved visualization of the facial nerve and its surrounding perineural vascular plexus [7,19,111,113]. In general, Bell palsy patients do not need to be imaged unless the symptoms are atypical, recurrent, or persistent for 2 to 4 months [102]. When imaging is considered, MRI is the method of choice. Variable abnormal enhancement patterns may be seen in the canalicular, labyrinthine, geniculate, tympanic, and mastoid portions of the nerve [106,117-122]. There is a lack of consensus regarding the prognostic value of MRI in Bell palsy [118-121], and MRI is most useful for excluding other causes of facial nerve palsy. High-resolution thin-cut contrast-enhanced MRI is an especially useful method to evaluate for perineural spread of a tumor, which can affect CN VII and is discussed in Variant 10. Sensitivities for MRI detection of perineural spread of a tumor range from 73% to 100% and vary according to the nerve evaluated and timing of imaging relative to tissue sampling [65,104,123-125]. In patients with clinical features of hemifacial spasm, 3-D heavily T2-weighted MRI sequences and MRA are noninvasive methods for characterizing the anatomy of vascular loops potentially compressing the centrally myelinated portion of the facial nerve and correlate well with surgical findings [76,78,100,101,110].

69509

acrac_69509_17

Cranial Neuropathy

Both false- positive and false-negative imaging studies occur when assessing for neurovascular contact in the setting of hemifacial spasm; consequently MRI is supportive rather than diagnostic in selecting candidates for microvascular decompression [78,100]. In patients with failed initial microvascular decompression surgery, heavily T2-weighted MRI may be helpful to delineate the cause [101]. DTI is an advanced imaging technique that may be useful in assessing the facial nerve. Several studies suggest that DTI is accurate for the preoperative localization of the cisternal facial nerve to avoid iatrogenic injury in patients with cerebellopontine angle tumors [107,126-128]. Research indicates that DTI may have future use localizing the intraparotid facial nerve and detecting perineural spread of tumor [129,130]. US Neck There is no relevant literature to support the use of US neck in the evaluation of isolated unilateral facial nerve palsy or hemifacial spasm. Variant 4: Multiple different middle cranial nerve palsies (CN V-VII). Initial imaging. Multiple CN nuclei are closely approximated within the brainstem, from which motor fibers originate and sensory fibers terminate. A small single brainstem lesion can produce severe and mixed neurologic deficits, including multiple cranial neuropathies, often times with some component of cerebellar, motor, or somatosensory deficit helping in clinically localizing the lesion. The pons connects the midbrain to the medulla. The dorsal pontine tegmentum contains white matter tracts and CN V through CN VIII nuclei, and the ventral pons contains corticospinal, corticobulbar, and corticopontine tracts [1,131]. After exiting the pons, the first and second divisions of the trigeminal nerve course along the lateral wall of the cavernous sinus, the abducens nerve courses through the cavernous sinus, and CNs VII and VIII extend through the cerebellopontine angle toward the porus acusticus. The third division of the trigeminal exits the skull base via foramen ovale.

Cranial Neuropathy. Both false- positive and false-negative imaging studies occur when assessing for neurovascular contact in the setting of hemifacial spasm; consequently MRI is supportive rather than diagnostic in selecting candidates for microvascular decompression [78,100]. In patients with failed initial microvascular decompression surgery, heavily T2-weighted MRI may be helpful to delineate the cause [101]. DTI is an advanced imaging technique that may be useful in assessing the facial nerve. Several studies suggest that DTI is accurate for the preoperative localization of the cisternal facial nerve to avoid iatrogenic injury in patients with cerebellopontine angle tumors [107,126-128]. Research indicates that DTI may have future use localizing the intraparotid facial nerve and detecting perineural spread of tumor [129,130]. US Neck There is no relevant literature to support the use of US neck in the evaluation of isolated unilateral facial nerve palsy or hemifacial spasm. Variant 4: Multiple different middle cranial nerve palsies (CN V-VII). Initial imaging. Multiple CN nuclei are closely approximated within the brainstem, from which motor fibers originate and sensory fibers terminate. A small single brainstem lesion can produce severe and mixed neurologic deficits, including multiple cranial neuropathies, often times with some component of cerebellar, motor, or somatosensory deficit helping in clinically localizing the lesion. The pons connects the midbrain to the medulla. The dorsal pontine tegmentum contains white matter tracts and CN V through CN VIII nuclei, and the ventral pons contains corticospinal, corticobulbar, and corticopontine tracts [1,131]. After exiting the pons, the first and second divisions of the trigeminal nerve course along the lateral wall of the cavernous sinus, the abducens nerve courses through the cavernous sinus, and CNs VII and VIII extend through the cerebellopontine angle toward the porus acusticus. The third division of the trigeminal exits the skull base via foramen ovale.

69509

acrac_69509_18

Cranial Neuropathy

Pontine lesions can affect CNs V, VI, VII, and/or VIII. Ischemic and hemorrhagic infarcts are the most frequent cause of acute brainstem syndromes with the pons most frequently affected [1,132]. Nonischemic lesions affecting Cranial Neuropathy the brainstem include trauma, demyelinating disease, encephalitis, neoplasms, central pontine myelinolysis, neurodegenerative disorders, and syringobulbia [18,131,132]. Pontine syndromes causing variable involvement of CNs V-VIII, along with other neurologic deficits, include Millard-Gubler syndrome, Foville syndrome, locked-in syndrome, and facial colliculus syndrome [131]. The internal carotid artery with its surrounding sympathetic plexus and the abducens nerve extend through the center of the cavernous sinus, and the oculomotor, trochlear, and trigeminal nerves (1st and 2nd division) extend along the lateral wall of the cavernous sinus. Cavernous sinus lesions can result in isolated or multiple cranial neuropathies including involvement of the abducens and trigeminal nerves. Tumors, vascular lesions, infection, and inflammatory disorders can lead to cavernous sinus syndrome [18]. The cerebellopontine angle spans a craniocaudal extent that encompasses the cisternal portions of CNs V-X and is most frequently affected by benign tumors. Sensorineural hearing loss and tinnitus are the most common symptoms but can be accompanied by neuropathies of CNs V, VI, VII, IX, and X with larger tumors [18]. The combination of ipsilateral CN V and CN VII palsies raises concern for perineural spread of tumor, which is discussed in Variant 10. Additionally, leptomeningeal processes can lead to variable patterns of cranial neuropathy [18,132]. CT Maxillofacial There is no relevant literature to support the use of maxillofacial CT in the initial evaluation of multiple middle CN palsies.

Cranial Neuropathy. Pontine lesions can affect CNs V, VI, VII, and/or VIII. Ischemic and hemorrhagic infarcts are the most frequent cause of acute brainstem syndromes with the pons most frequently affected [1,132]. Nonischemic lesions affecting Cranial Neuropathy the brainstem include trauma, demyelinating disease, encephalitis, neoplasms, central pontine myelinolysis, neurodegenerative disorders, and syringobulbia [18,131,132]. Pontine syndromes causing variable involvement of CNs V-VIII, along with other neurologic deficits, include Millard-Gubler syndrome, Foville syndrome, locked-in syndrome, and facial colliculus syndrome [131]. The internal carotid artery with its surrounding sympathetic plexus and the abducens nerve extend through the center of the cavernous sinus, and the oculomotor, trochlear, and trigeminal nerves (1st and 2nd division) extend along the lateral wall of the cavernous sinus. Cavernous sinus lesions can result in isolated or multiple cranial neuropathies including involvement of the abducens and trigeminal nerves. Tumors, vascular lesions, infection, and inflammatory disorders can lead to cavernous sinus syndrome [18]. The cerebellopontine angle spans a craniocaudal extent that encompasses the cisternal portions of CNs V-X and is most frequently affected by benign tumors. Sensorineural hearing loss and tinnitus are the most common symptoms but can be accompanied by neuropathies of CNs V, VI, VII, IX, and X with larger tumors [18]. The combination of ipsilateral CN V and CN VII palsies raises concern for perineural spread of tumor, which is discussed in Variant 10. Additionally, leptomeningeal processes can lead to variable patterns of cranial neuropathy [18,132]. CT Maxillofacial There is no relevant literature to support the use of maxillofacial CT in the initial evaluation of multiple middle CN palsies.

69509

acrac_69509_19

Cranial Neuropathy

Depending on institutional protocols used for high-resolution skull base imaging, maxillofacial CT may be complementary to an MRI exam if a skull base lesion is found to be the cause of multiple middle CN palsies and can be useful to characterize the osseous integrity of the skull base, intratumoral calcification, and skull base foramina [134]. Contrast should be administered. Noncontrast CT may also be an alternate option when used as complementary to the MRI. There is no relevant literature to support the use of combined pre- and postcontrast imaging. CT Temporal Bone There is no relevant literature to support the use of temporal bone CT in the initial evaluation of multiple middle CN palsies. Depending on institutional protocols used for high-resolution skull base imaging, temporal bone CT may be complementary to contrast-enhanced MRI if a skull base lesion is found to be the cause of multiple middle CN palsies and can be useful to characterize the osseous integrity of the base, intratumoral calcification, and skull base foramina [134]. Contrast should be administered. Noncontrast CT may also be an alternate option when used as complementary to the MRI. There is no relevant literature to support the use of combined pre- and postcontrast imaging. CT Neck There is no relevant literature to support routine use of neck CT in the initial evaluation of multiple middle cranial palsies. If perineural tumor spread (discussed in Variant 10) is suspected based on clinical features, most notably involving both CNs V and VII, neck CT is complementary to MRI for characterizing osseous changes of skull base neural foramina and may be useful to characterize perineural fat and stage the neck [64,66]. Contrast should be administered if possible. There is no relevant literature to support the use of combined pre- and postcontrast imaging. CTA Head There is no relevant literature to support routine use of CTA head in the initial evaluation of multiple middle cranial palsies.

Cranial Neuropathy. Depending on institutional protocols used for high-resolution skull base imaging, maxillofacial CT may be complementary to an MRI exam if a skull base lesion is found to be the cause of multiple middle CN palsies and can be useful to characterize the osseous integrity of the skull base, intratumoral calcification, and skull base foramina [134]. Contrast should be administered. Noncontrast CT may also be an alternate option when used as complementary to the MRI. There is no relevant literature to support the use of combined pre- and postcontrast imaging. CT Temporal Bone There is no relevant literature to support the use of temporal bone CT in the initial evaluation of multiple middle CN palsies. Depending on institutional protocols used for high-resolution skull base imaging, temporal bone CT may be complementary to contrast-enhanced MRI if a skull base lesion is found to be the cause of multiple middle CN palsies and can be useful to characterize the osseous integrity of the base, intratumoral calcification, and skull base foramina [134]. Contrast should be administered. Noncontrast CT may also be an alternate option when used as complementary to the MRI. There is no relevant literature to support the use of combined pre- and postcontrast imaging. CT Neck There is no relevant literature to support routine use of neck CT in the initial evaluation of multiple middle cranial palsies. If perineural tumor spread (discussed in Variant 10) is suspected based on clinical features, most notably involving both CNs V and VII, neck CT is complementary to MRI for characterizing osseous changes of skull base neural foramina and may be useful to characterize perineural fat and stage the neck [64,66]. Contrast should be administered if possible. There is no relevant literature to support the use of combined pre- and postcontrast imaging. CTA Head There is no relevant literature to support routine use of CTA head in the initial evaluation of multiple middle cranial palsies.

69509

acrac_69509_20

Cranial Neuropathy

Ischemic and hemorrhagic infarcts are the most frequent cause of acute brainstem syndromes, which can result in multiple middle CN palsies [131,132,135]. CTA may be complementary to brain MRI or head CT to characterize the vasculature in these clinical scenarios. Cranial Neuropathy FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use FDG-PET/CT skull base to mid-thigh in the initial evaluation of multiple middle cranial palsies. MRA Head There is no relevant literature to support routine use of MRA head in the initial evaluation of multiple middle cranial palsies. Ischemic and hemorrhagic infarcts are the most frequent cause of acute brainstem syndromes, which can result in multiple middle CN palsies [131,132,135]. MRA may be complementary to MRI brain to characterize the vasculature in these clinical scenarios. DWI can be used to assess for acute brainstem infarction, cholesteatoma, and for characterizing tumor cellularity. False-negative DWI can occur in the setting of very small ischemic brainstem infarcts [137,138]. Thin-section coronal DWI or thinner axial DWI may improve sensitivity for detecting acute brainstem infarction, with nearly 25% of acute brainstem infarcts more easily seen on thin-cut coronal DWI compared with standard axial DWI in one study [138]. The combination of ipsilateral CN V and CN VII palsies raises concern for perineural spread of a tumor, which is discussed in Variant 10. DWI can be used to assess for acute brainstem infarction, cholesteatoma, and for characterizing tumor cellularity. False-negative DWI can occur in the setting of very small ischemic brainstem infarcts [137,138]. Thin-section coronal DWI or thinner axial DWI may improve sensitivity for detecting acute brainstem infarction, with nearly 25% of acute brainstem infarcts more easily seen on thin-cut coronal DWI compared with standard axial DWI in one study [138].

Cranial Neuropathy. Ischemic and hemorrhagic infarcts are the most frequent cause of acute brainstem syndromes, which can result in multiple middle CN palsies [131,132,135]. CTA may be complementary to brain MRI or head CT to characterize the vasculature in these clinical scenarios. Cranial Neuropathy FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use FDG-PET/CT skull base to mid-thigh in the initial evaluation of multiple middle cranial palsies. MRA Head There is no relevant literature to support routine use of MRA head in the initial evaluation of multiple middle cranial palsies. Ischemic and hemorrhagic infarcts are the most frequent cause of acute brainstem syndromes, which can result in multiple middle CN palsies [131,132,135]. MRA may be complementary to MRI brain to characterize the vasculature in these clinical scenarios. DWI can be used to assess for acute brainstem infarction, cholesteatoma, and for characterizing tumor cellularity. False-negative DWI can occur in the setting of very small ischemic brainstem infarcts [137,138]. Thin-section coronal DWI or thinner axial DWI may improve sensitivity for detecting acute brainstem infarction, with nearly 25% of acute brainstem infarcts more easily seen on thin-cut coronal DWI compared with standard axial DWI in one study [138]. The combination of ipsilateral CN V and CN VII palsies raises concern for perineural spread of a tumor, which is discussed in Variant 10. DWI can be used to assess for acute brainstem infarction, cholesteatoma, and for characterizing tumor cellularity. False-negative DWI can occur in the setting of very small ischemic brainstem infarcts [137,138]. Thin-section coronal DWI or thinner axial DWI may improve sensitivity for detecting acute brainstem infarction, with nearly 25% of acute brainstem infarcts more easily seen on thin-cut coronal DWI compared with standard axial DWI in one study [138].

69509

acrac_69509_21

Cranial Neuropathy

The combination of ipsilateral CN V and CN VII palsies raises concern for perineural spread of a tumor, which is discussed in Variant 10. US Neck There is no relevant literature to support the use of US neck in the initial evaluation of multiple middle cranial palsies. Variant 5: Oropharyngeal neurogenic dysphagia or oropharyngeal pain (glossopharyngeal nerve, CN IX). Initial imaging. The glossopharyngeal nerve (CN IX) arises in the medulla and is responsible for branchial motor innervation to the stylopharyngeus muscle, which elevates the palate, and visceral motor parasympathetic innervation to the parotid gland [2]. Visceral sensory innervation to the carotid sinus plays a role in regulating circulation and general and special sensory innervation supply sensation and taste to the posterior tongue. The nerve exits the jugular foramen in close proximity to the vagus (CN X) and the spinal accessory (CN XI) nerves [2,24]. Noniatrogenic isolated syndromes involving the glossopharyngeal nerve are very rare. Nerve root section or nerve ablation results in Cranial Neuropathy variable degrees of dysphagia and ipsilateral sensory loss on the pharynx and posterior tongue [139]. Intra- parenchymal lesions can affect CN IX, including gliomas, lymphomas, metastases, vascular malformations, infarctions, demyelinating lesions, and inflammatory abnormalities. Leptomeningeal metastases, granulomatous disease, and even tortuosity or aneurysmal dilatation of vessels may affect the nerve as it enters the subarachnoid cistern. Lesions in the region of the posterior skull base and jugular foramen, such as metastases, schwannomas, paragangliomas, and meningiomas, usually also involve the other lower CNs [140,141]. Tonsillar pain syndromes and loss of a gag reflex accompanied by impaired taste and sensation along the posterior one-third of the tongue and palate may signal a glossopharyngeal nerve lesion [2,141].

Cranial Neuropathy. The combination of ipsilateral CN V and CN VII palsies raises concern for perineural spread of a tumor, which is discussed in Variant 10. US Neck There is no relevant literature to support the use of US neck in the initial evaluation of multiple middle cranial palsies. Variant 5: Oropharyngeal neurogenic dysphagia or oropharyngeal pain (glossopharyngeal nerve, CN IX). Initial imaging. The glossopharyngeal nerve (CN IX) arises in the medulla and is responsible for branchial motor innervation to the stylopharyngeus muscle, which elevates the palate, and visceral motor parasympathetic innervation to the parotid gland [2]. Visceral sensory innervation to the carotid sinus plays a role in regulating circulation and general and special sensory innervation supply sensation and taste to the posterior tongue. The nerve exits the jugular foramen in close proximity to the vagus (CN X) and the spinal accessory (CN XI) nerves [2,24]. Noniatrogenic isolated syndromes involving the glossopharyngeal nerve are very rare. Nerve root section or nerve ablation results in Cranial Neuropathy variable degrees of dysphagia and ipsilateral sensory loss on the pharynx and posterior tongue [139]. Intra- parenchymal lesions can affect CN IX, including gliomas, lymphomas, metastases, vascular malformations, infarctions, demyelinating lesions, and inflammatory abnormalities. Leptomeningeal metastases, granulomatous disease, and even tortuosity or aneurysmal dilatation of vessels may affect the nerve as it enters the subarachnoid cistern. Lesions in the region of the posterior skull base and jugular foramen, such as metastases, schwannomas, paragangliomas, and meningiomas, usually also involve the other lower CNs [140,141]. Tonsillar pain syndromes and loss of a gag reflex accompanied by impaired taste and sensation along the posterior one-third of the tongue and palate may signal a glossopharyngeal nerve lesion [2,141].

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Cranial Neuropathy

Glossopharyngeal neuralgia presents as severe pain in the oropharyngeal and otic regions, classically triggered by swallowing, and is typically caused by neurovascular compression, although a minority of cases may be caused by trauma, an elongated calcified stylohyoid ligament, and neoplasms along the course of the nerve, including in the neck [142,143]. CT Head There is no relevant literature to support the use of routine noncontrast head CT in the initial evaluation of oropharyngeal neurogenic dysphagia or oropharyngeal pain. CT Maxillofacial There is no relevant literature to support the use of maxillofacial CT in the initial evaluation of oropharyngeal neurogenic dysphagia or oropharyngeal pain. CT Temporal Bone There is no relevant literature to support the use of temporal bone CT in the initial evaluation of oropharyngeal neurogenic dysphagia or oropharyngeal pain. CT Neck Neck CT is complementary to MRI orbits, face, and neck in assessing patients with isolated CN IX palsy. Neck CT can delineate skull base erosion, identify deep space neck masses, intratumoral calcification, and the bony margins of the jugular foramen and nearby skull base foramina as well as image the extracranial course of the CN IX and its innervated structures in the pharynx and carotid space [144-148]. It does not image the intracranial course of CN IX or the brainstem well, which are best assessed with MRI. Imaging protocols should include thin-cut high- resolution bone windows through the posterior skull base. Contrast is strongly preferred for soft tissue characterization. There is no relevant literature to support the use of combined pre- and postcontrast imaging. CT neck is also useful to characterize the anatomy of the stylohyoid ligament in patients with glossopharyngeal pain [142]. In cases of glossopharyngeal neuralgia, imaging should include the pharynx and larynx to exclude a mucosal neoplasm as an etiology.

Cranial Neuropathy. Glossopharyngeal neuralgia presents as severe pain in the oropharyngeal and otic regions, classically triggered by swallowing, and is typically caused by neurovascular compression, although a minority of cases may be caused by trauma, an elongated calcified stylohyoid ligament, and neoplasms along the course of the nerve, including in the neck [142,143]. CT Head There is no relevant literature to support the use of routine noncontrast head CT in the initial evaluation of oropharyngeal neurogenic dysphagia or oropharyngeal pain. CT Maxillofacial There is no relevant literature to support the use of maxillofacial CT in the initial evaluation of oropharyngeal neurogenic dysphagia or oropharyngeal pain. CT Temporal Bone There is no relevant literature to support the use of temporal bone CT in the initial evaluation of oropharyngeal neurogenic dysphagia or oropharyngeal pain. CT Neck Neck CT is complementary to MRI orbits, face, and neck in assessing patients with isolated CN IX palsy. Neck CT can delineate skull base erosion, identify deep space neck masses, intratumoral calcification, and the bony margins of the jugular foramen and nearby skull base foramina as well as image the extracranial course of the CN IX and its innervated structures in the pharynx and carotid space [144-148]. It does not image the intracranial course of CN IX or the brainstem well, which are best assessed with MRI. Imaging protocols should include thin-cut high- resolution bone windows through the posterior skull base. Contrast is strongly preferred for soft tissue characterization. There is no relevant literature to support the use of combined pre- and postcontrast imaging. CT neck is also useful to characterize the anatomy of the stylohyoid ligament in patients with glossopharyngeal pain [142]. In cases of glossopharyngeal neuralgia, imaging should include the pharynx and larynx to exclude a mucosal neoplasm as an etiology.

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Cranial Neuropathy

CTA Head and Neck There is no relevant literature to support the use of CTA in the initial evaluation of oropharyngeal neurogenic dysphagia or oropharyngeal pain. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of FDG-PET/CT skull base to mid-thigh in the initial evaluation of oropharyngeal neurogenic dysphagia or oropharyngeal pain. MRA Head and Neck There is no relevant literature to support routine use of MRA head and neck to assess vasculature in the initial evaluation of glossopharyngeal palsy, although MRA focused on the posterior skull base can be complementary to thin-cut high-resolution skull base technique, contrast-enhanced MRI orbits, face, and neck, or MRI head in patients with glossopharyngeal nerve palsy. Contrast-enhanced MRA focused on the posterior skull provides detailed imaging of the lower CNs within the jugular foramen and their relationship to the hypoglossal nerve as they exit the skull base, with CN IX reportedly well imaged in 100% of cases using contrast-enhanced high-resolution MRA [24,149]. MRA can be complementary to thin-cut high-resolution MRI sequences to assess for neurovascular compression in patients with glossopharyngeal neuralgia and has demonstrated agreement with surgically confirmed neurovascular compression in all patients in 2 small studies [143,149,150]. Cranial Neuropathy Thin-cut heavily T2-weighted contrast-enhanced modified balanced SSFP sequences and contrast-enhanced MRA focused on the posterior skull provide detailed imaging of the nerves within the jugular foramen and their relationship to the hypoglossal nerve as they exit the skull base, visualizing CN IX in 90% to 100% of imaged patients [24]. Various combinations of high-resolution 3-D T2-weighted imaging, MRA, and 3-D T1-weighted contrast-enhanced sequences can be used to assess for neurovascular compression [143,149-151] and have demonstrated agreement with surgical findings in all patients in two small studies [143,150].

Cranial Neuropathy. CTA Head and Neck There is no relevant literature to support the use of CTA in the initial evaluation of oropharyngeal neurogenic dysphagia or oropharyngeal pain. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of FDG-PET/CT skull base to mid-thigh in the initial evaluation of oropharyngeal neurogenic dysphagia or oropharyngeal pain. MRA Head and Neck There is no relevant literature to support routine use of MRA head and neck to assess vasculature in the initial evaluation of glossopharyngeal palsy, although MRA focused on the posterior skull base can be complementary to thin-cut high-resolution skull base technique, contrast-enhanced MRI orbits, face, and neck, or MRI head in patients with glossopharyngeal nerve palsy. Contrast-enhanced MRA focused on the posterior skull provides detailed imaging of the lower CNs within the jugular foramen and their relationship to the hypoglossal nerve as they exit the skull base, with CN IX reportedly well imaged in 100% of cases using contrast-enhanced high-resolution MRA [24,149]. MRA can be complementary to thin-cut high-resolution MRI sequences to assess for neurovascular compression in patients with glossopharyngeal neuralgia and has demonstrated agreement with surgically confirmed neurovascular compression in all patients in 2 small studies [143,149,150]. Cranial Neuropathy Thin-cut heavily T2-weighted contrast-enhanced modified balanced SSFP sequences and contrast-enhanced MRA focused on the posterior skull provide detailed imaging of the nerves within the jugular foramen and their relationship to the hypoglossal nerve as they exit the skull base, visualizing CN IX in 90% to 100% of imaged patients [24]. Various combinations of high-resolution 3-D T2-weighted imaging, MRA, and 3-D T1-weighted contrast-enhanced sequences can be used to assess for neurovascular compression [143,149-151] and have demonstrated agreement with surgical findings in all patients in two small studies [143,150].

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Cranial Neuropathy

Thin-cut heavily T2-weighted contrast-enhanced modified balanced SSFP sequences and contrast-enhanced MRA focused on the posterior skull provide detailed imaging of the nerves within the jugular foramen and their relationship to the hypoglossal nerve as they exit the skull base, visualizing CN IX in 90% to 100% of imaged patients [24]. Various combinations of high-resolution 3-D T2-weighted imaging, MRA, and 3-D T1-weighted contrast-enhanced sequences can be used to assess for neurovascular compression [143,149-151] and have demonstrated agreement with surgical findings in all patients in two small studies [143,150]. US Neck There is no relevant literature to support the use of US neck in the initial evaluation of oropharyngeal neurogenic dysphagia or oropharyngeal pain. Variant 6: Unilateral isolated palatal or vocal cord paralysis or both (vagal nerve, CN X). Initial imaging. The vagus nerve (CN X) supplies visceral sensation to the pharynx, larynx, and viscera and general sensation to the ear. Branchial motor branches innervate muscles of the pharynx via the pharyngeal branches and the larynx via the superior and recurrent laryngeal nerves, and visceral motor branches play a predominant role in parasympathetic supply to the thorax and abdomen [2]. The vagus nerve runs the longest course in the body of any CN and is therefore vulnerable to a wide range of pathologies occurring throughout its trajectory from the posterior fossa and skull base to the neck, thorax, and abdomen. Within the neck it descends in the posterior carotid sheath. At the base of the neck, the recurrent laryngeal branch of the right vagus nerve turns upward and medial posterior to the subclavian artery, ascending in the tracheoesophageal groove. The left recurrent laryngeal nerve arises to the left of the aortic arch, turns upward in the aortopulmonary window beneath the ligamentum arteriosum, ascending in the left tracheoesophageal groove.

Cranial Neuropathy. Thin-cut heavily T2-weighted contrast-enhanced modified balanced SSFP sequences and contrast-enhanced MRA focused on the posterior skull provide detailed imaging of the nerves within the jugular foramen and their relationship to the hypoglossal nerve as they exit the skull base, visualizing CN IX in 90% to 100% of imaged patients [24]. Various combinations of high-resolution 3-D T2-weighted imaging, MRA, and 3-D T1-weighted contrast-enhanced sequences can be used to assess for neurovascular compression [143,149-151] and have demonstrated agreement with surgical findings in all patients in two small studies [143,150]. US Neck There is no relevant literature to support the use of US neck in the initial evaluation of oropharyngeal neurogenic dysphagia or oropharyngeal pain. Variant 6: Unilateral isolated palatal or vocal cord paralysis or both (vagal nerve, CN X). Initial imaging. The vagus nerve (CN X) supplies visceral sensation to the pharynx, larynx, and viscera and general sensation to the ear. Branchial motor branches innervate muscles of the pharynx via the pharyngeal branches and the larynx via the superior and recurrent laryngeal nerves, and visceral motor branches play a predominant role in parasympathetic supply to the thorax and abdomen [2]. The vagus nerve runs the longest course in the body of any CN and is therefore vulnerable to a wide range of pathologies occurring throughout its trajectory from the posterior fossa and skull base to the neck, thorax, and abdomen. Within the neck it descends in the posterior carotid sheath. At the base of the neck, the recurrent laryngeal branch of the right vagus nerve turns upward and medial posterior to the subclavian artery, ascending in the tracheoesophageal groove. The left recurrent laryngeal nerve arises to the left of the aortic arch, turns upward in the aortopulmonary window beneath the ligamentum arteriosum, ascending in the left tracheoesophageal groove.

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Cranial Neuropathy

The recurrent laryngeal nerves innervate all the laryngeal muscles, with the exception of the cricothyroid. Isolated vagal palsy can be central or peripheral, due to complete vagal nerve dysfunction or isolated impairment of the recurrent laryngeal nerve, respectively. Lesions proximal to the pharyngeal branches cause ipsilateral palatal weakness. Because lesions anywhere along the course of the vagus nerve may potentially cause vocal cord paralysis, Cranial Neuropathy the imaging protocol must visualize the full extent of the nerve from the skull base to the mid chest in this situation [2,152]. In the case of a central palsy, careful neurologic examination and patient history may help to locate the lesion to the central nervous system. Intramedullary lesions that can affect the vagus nucleus include demyelination, infarction, neoplasms, motor neuron disorders, and syringobulbia. Intracranial processes such as meningiomas, schwannomas, metastases, granulomatous disease, and infection may affect the nerve as it exits the medulla. Paragangliomas, schwannomas, meningiomas, and metastases involving the skull base may affect the vagus nerve and the neighboring glossopharyngeal nerve (CN IX) or accessory nerve (CN XI) by infiltration of fibers or by compression [2,152,153]. Direct and indirect signs of vocal cord paralysis can be seen on CT [152]. Optimal evidence-based imaging algorithms in the setting of unilateral vocal cord paralysis without an apparent cause are not established. One of the most troubling symptoms of vagus dysfunction is vocal cord paralysis. Injury of the recurrent laryngeal branch in the neck or upper thorax can be idiopathic, due to iatrogenic injury from surgery or intubation, trauma, infection, inflammation, vascular lesions, and neoplasms arising in the neck and thorax. Moreover, thoracic causes of vocal cord paralysis, such as lung cancer, tuberculosis, and thoracic aortic aneurysm, are common [154-157].

Cranial Neuropathy. The recurrent laryngeal nerves innervate all the laryngeal muscles, with the exception of the cricothyroid. Isolated vagal palsy can be central or peripheral, due to complete vagal nerve dysfunction or isolated impairment of the recurrent laryngeal nerve, respectively. Lesions proximal to the pharyngeal branches cause ipsilateral palatal weakness. Because lesions anywhere along the course of the vagus nerve may potentially cause vocal cord paralysis, Cranial Neuropathy the imaging protocol must visualize the full extent of the nerve from the skull base to the mid chest in this situation [2,152]. In the case of a central palsy, careful neurologic examination and patient history may help to locate the lesion to the central nervous system. Intramedullary lesions that can affect the vagus nucleus include demyelination, infarction, neoplasms, motor neuron disorders, and syringobulbia. Intracranial processes such as meningiomas, schwannomas, metastases, granulomatous disease, and infection may affect the nerve as it exits the medulla. Paragangliomas, schwannomas, meningiomas, and metastases involving the skull base may affect the vagus nerve and the neighboring glossopharyngeal nerve (CN IX) or accessory nerve (CN XI) by infiltration of fibers or by compression [2,152,153]. Direct and indirect signs of vocal cord paralysis can be seen on CT [152]. Optimal evidence-based imaging algorithms in the setting of unilateral vocal cord paralysis without an apparent cause are not established. One of the most troubling symptoms of vagus dysfunction is vocal cord paralysis. Injury of the recurrent laryngeal branch in the neck or upper thorax can be idiopathic, due to iatrogenic injury from surgery or intubation, trauma, infection, inflammation, vascular lesions, and neoplasms arising in the neck and thorax. Moreover, thoracic causes of vocal cord paralysis, such as lung cancer, tuberculosis, and thoracic aortic aneurysm, are common [154-157].

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Cranial Neuropathy

CT Chest Evaluation of the posterior fossa, neck, and upper chest is necessary for complete evaluation of the CN X, including the recurrent laryngeal nerve. Below the skull base, the vagus nerve is not directly imaged, although its course from the skull base to the carina can be imaged with contrast-enhanced neck CT extended through the aortopulmonary window. CT chest alone does cover the entire course of the vagus nerve, but it can be combined simultaneously and sequentially with CT neck to image the intrathoracic course of the vagus nerve. Preferably contrast should be administered. There is no relevant literature to support the use of combined pre- and postcontrast imaging. Although chest radiographs may detect large thoracic causes of vocal cord paralysis, chest CT is more sensitive, particularly for detecting aortopulmonary window and paratracheal lesions [158]. CT Head There is no relevant literature to support the use of routine CT head alone in the evaluation of unilateral isolated vagal nerve palsy. CT Maxillofacial There is no relevant literature to support the use of maxillofacial CT in the evaluation of isolated CN X palsy. Contrast-enhanced neck CT extended through the aortopulmonary window is useful for initial evaluation of isolated CN X palsy and allows imaging of the osseous integrity of the skull base and assessment of the full extent of the recurrent laryngeal nerve. CT Temporal Bone There is no relevant literature to support the use of temporal bone CT in the evaluation of isolated CN X palsy. CT Neck Evaluation of the posterior fossa, neck, and upper chest is necessary for complete evaluation of the CN X, including the recurrent laryngeal nerve, and can be achieved well with contrast-enhanced neck CT extended through the AP window. Below the skull base, the vagus nerve is not directly visualized, although its course from the skull base to the carina can be imaged with neck CT.

Cranial Neuropathy. CT Chest Evaluation of the posterior fossa, neck, and upper chest is necessary for complete evaluation of the CN X, including the recurrent laryngeal nerve. Below the skull base, the vagus nerve is not directly imaged, although its course from the skull base to the carina can be imaged with contrast-enhanced neck CT extended through the aortopulmonary window. CT chest alone does cover the entire course of the vagus nerve, but it can be combined simultaneously and sequentially with CT neck to image the intrathoracic course of the vagus nerve. Preferably contrast should be administered. There is no relevant literature to support the use of combined pre- and postcontrast imaging. Although chest radiographs may detect large thoracic causes of vocal cord paralysis, chest CT is more sensitive, particularly for detecting aortopulmonary window and paratracheal lesions [158]. CT Head There is no relevant literature to support the use of routine CT head alone in the evaluation of unilateral isolated vagal nerve palsy. CT Maxillofacial There is no relevant literature to support the use of maxillofacial CT in the evaluation of isolated CN X palsy. Contrast-enhanced neck CT extended through the aortopulmonary window is useful for initial evaluation of isolated CN X palsy and allows imaging of the osseous integrity of the skull base and assessment of the full extent of the recurrent laryngeal nerve. CT Temporal Bone There is no relevant literature to support the use of temporal bone CT in the evaluation of isolated CN X palsy. CT Neck Evaluation of the posterior fossa, neck, and upper chest is necessary for complete evaluation of the CN X, including the recurrent laryngeal nerve, and can be achieved well with contrast-enhanced neck CT extended through the AP window. Below the skull base, the vagus nerve is not directly visualized, although its course from the skull base to the carina can be imaged with neck CT.

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Cranial Neuropathy

With its rapid scanning time, high-spatial resolution, and multiplanar capability, contrast-enhanced neck CT conveniently allows imaging of the jugular foramen, the full extracranial course of the vagus nerve, direct imaging of the larynx, and assessment of the full extent of the recurrent laryngeal nerve when extended through the aortopulmonary window. Imaging protocols should include thin-cut high- resolution bone windows through the posterior skull base. Contrast should be administered. Noncontrast neck CT offers limited evaluation of the neck and may be an alternate option for this clinical scenario. There is no relevant literature to support the use of combined pre- and postcontrast imaging. Direct and indirect signs of vocal cord paralysis can be seen on CT [152]. CT may differentiate traumatic arytenoid dislocation from neurogenic paralysis [153]. Optimal evidence-based imaging algorithms in the setting of unilateral vocal cord paralysis without an apparent cause are not established. Several studies support the use of CT for detecting a cause for unilateral vocal cord paralysis with diagnostic yields ranging from 23.5% to 47.5% [155,157]. One study found CT had a higher diagnostic yield of 40% among patients >65 years of age [131]. In patients with a diagnosis of idiopathic vocal cord Cranial Neuropathy paralysis, repeat CT may be helpful to detect occult causes of paralysis [156]. Other studies report low diagnostic yields ranging from 0% to 6% [159-161]. Noninvasive virtual laryngoscopy using ultrahigh-resolution CT and cine MRI allowing the patient to perform phonation and breathing maneuvers during imaging are emerging technologies [162,163]. CTA Head and Neck There is no relevant literature to support the use of CTA in the evaluation of unilateral isolated vagal nerve palsy. FDG-PET/CT Skull Base to Mid-Thigh FDG-PET/CT is not routinely used in the initial evaluation of vocal cord paralysis or vagus nerve palsy.

Cranial Neuropathy. With its rapid scanning time, high-spatial resolution, and multiplanar capability, contrast-enhanced neck CT conveniently allows imaging of the jugular foramen, the full extracranial course of the vagus nerve, direct imaging of the larynx, and assessment of the full extent of the recurrent laryngeal nerve when extended through the aortopulmonary window. Imaging protocols should include thin-cut high- resolution bone windows through the posterior skull base. Contrast should be administered. Noncontrast neck CT offers limited evaluation of the neck and may be an alternate option for this clinical scenario. There is no relevant literature to support the use of combined pre- and postcontrast imaging. Direct and indirect signs of vocal cord paralysis can be seen on CT [152]. CT may differentiate traumatic arytenoid dislocation from neurogenic paralysis [153]. Optimal evidence-based imaging algorithms in the setting of unilateral vocal cord paralysis without an apparent cause are not established. Several studies support the use of CT for detecting a cause for unilateral vocal cord paralysis with diagnostic yields ranging from 23.5% to 47.5% [155,157]. One study found CT had a higher diagnostic yield of 40% among patients >65 years of age [131]. In patients with a diagnosis of idiopathic vocal cord Cranial Neuropathy paralysis, repeat CT may be helpful to detect occult causes of paralysis [156]. Other studies report low diagnostic yields ranging from 0% to 6% [159-161]. Noninvasive virtual laryngoscopy using ultrahigh-resolution CT and cine MRI allowing the patient to perform phonation and breathing maneuvers during imaging are emerging technologies [162,163]. CTA Head and Neck There is no relevant literature to support the use of CTA in the evaluation of unilateral isolated vagal nerve palsy. FDG-PET/CT Skull Base to Mid-Thigh FDG-PET/CT is not routinely used in the initial evaluation of vocal cord paralysis or vagus nerve palsy.

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Cranial Neuropathy

FDG- PET/CT may be useful after initial cross-sectional imaging in patients with a known primary malignancy for both staging and therapy assessment [164]. It may yield false-positive findings if not interpreted carefully in the clinical context in patients with vocal cord palsy or following vocal fold augmentation [152,165-167]. MRA Head and Neck There is no relevant literature to support the use of MRA in the evaluation of vasculature in unilateral isolated vagal nerve palsy. Thin-cut heavily T2-weighted contrast-enhanced modified balanced SSFP sequences and contrast-enhanced MRA focused on the posterior skull provide detailed imaging of the lower nerves within the jugular foramen, including CN X, which is well visualized in 94% to 100% of imaged patients [24]. Below the skull base, the vagus nerve is not directly imaged by CT and MRI, though its course from the skull base to the carina can be imaged by either modality. Contrast-enhanced CT is typically accessible and conveniently allows complete and rapid imaging of the full extracranial course of the vagus nerve and direct imaging of the larynx and can be extended into the upper thorax to cover the entire course of the left recurrent laryngeal nerve. Thin-cut heavily T2-weighted contrast-enhanced modified balanced SSFP sequences and contrast-enhanced MRA focused on the posterior skull provide detailed imaging of the lower nerves within the jugular foramen, including CN X, which is well visualized in 94% to 100% of imaged patients [24]. Below the skull base, the vagus nerve is not directly visible by CT and MRI, although its course from the skull base to the carina can be imaged by either modality. Contrast-enhanced CT is typically accessible and conveniently allows complete and rapid imaging of the full extracranial course of the vagus nerve and direct imaging of the larynx and can be extended into the upper thorax to cover the entire course of the left recurrent laryngeal nerve. Cranial Neuropathy

Cranial Neuropathy. FDG- PET/CT may be useful after initial cross-sectional imaging in patients with a known primary malignancy for both staging and therapy assessment [164]. It may yield false-positive findings if not interpreted carefully in the clinical context in patients with vocal cord palsy or following vocal fold augmentation [152,165-167]. MRA Head and Neck There is no relevant literature to support the use of MRA in the evaluation of vasculature in unilateral isolated vagal nerve palsy. Thin-cut heavily T2-weighted contrast-enhanced modified balanced SSFP sequences and contrast-enhanced MRA focused on the posterior skull provide detailed imaging of the lower nerves within the jugular foramen, including CN X, which is well visualized in 94% to 100% of imaged patients [24]. Below the skull base, the vagus nerve is not directly imaged by CT and MRI, though its course from the skull base to the carina can be imaged by either modality. Contrast-enhanced CT is typically accessible and conveniently allows complete and rapid imaging of the full extracranial course of the vagus nerve and direct imaging of the larynx and can be extended into the upper thorax to cover the entire course of the left recurrent laryngeal nerve. Thin-cut heavily T2-weighted contrast-enhanced modified balanced SSFP sequences and contrast-enhanced MRA focused on the posterior skull provide detailed imaging of the lower nerves within the jugular foramen, including CN X, which is well visualized in 94% to 100% of imaged patients [24]. Below the skull base, the vagus nerve is not directly visible by CT and MRI, although its course from the skull base to the carina can be imaged by either modality. Contrast-enhanced CT is typically accessible and conveniently allows complete and rapid imaging of the full extracranial course of the vagus nerve and direct imaging of the larynx and can be extended into the upper thorax to cover the entire course of the left recurrent laryngeal nerve. Cranial Neuropathy

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Cranial Neuropathy

Radiography Chest Chest radiography is not sufficient for the complete evaluation of thoracic causes that can contribute to vocal cord paralysis. Chest CT is more sensitive, particularly for detecting aortopulmonary window and paratracheal lesions [168]. Radiography can only reveal large lesions in the lung apex or mediastinum that may cause CN X deficits but fails to detect small clinically relevant lesions or pathology in the aortopulmonary window and the paratracheal region that can contribute to vocal cord paralysis [158,168]. US Neck US is not able to fully image the entire course of CN X in the posterior fossa or the recurrent laryngeal nerve extending into the upper thorax, both of which can be simultaneously imaged with contrast-enhanced neck CT extended through the AP window [157,158]. US is a complementary modality that can be used to guide biopsies of lesions in the neck that contribute to a CN X palsy [158]. Transcutaneous laryngeal US is an innovative, noninvasive technique that may be suitable to directly assess vocal cord movement in select patients at high risk for iatrogenic vocal cord palsy following surgery or intubation [169-174]. Variant 7: Unilateral isolated weakness or paralysis of the sternocleidomastoid and trapezius muscles (accessory nerve, CN XI). Initial imaging. The accessory nerve (CN XI) consists of a small cranial root originating from the nucleus ambiguous within the medulla oblongata and a large spinal root originating from the ventral horn of the spinal cord, between the C1 and C5 levels. The two components join and enter the pars vascularis of the jugular foramen [2]. The accessory nerve supplies portions of the sternocleidomastoid muscle and the upper portion of the trapezius muscle. Accessory nerve palsy is clinically manifested by weakness and atrophy of these muscles, causing decreased shoulder abduction, shoulder pain, cosmetic disfiguration, and disability.

Cranial Neuropathy. Radiography Chest Chest radiography is not sufficient for the complete evaluation of thoracic causes that can contribute to vocal cord paralysis. Chest CT is more sensitive, particularly for detecting aortopulmonary window and paratracheal lesions [168]. Radiography can only reveal large lesions in the lung apex or mediastinum that may cause CN X deficits but fails to detect small clinically relevant lesions or pathology in the aortopulmonary window and the paratracheal region that can contribute to vocal cord paralysis [158,168]. US Neck US is not able to fully image the entire course of CN X in the posterior fossa or the recurrent laryngeal nerve extending into the upper thorax, both of which can be simultaneously imaged with contrast-enhanced neck CT extended through the AP window [157,158]. US is a complementary modality that can be used to guide biopsies of lesions in the neck that contribute to a CN X palsy [158]. Transcutaneous laryngeal US is an innovative, noninvasive technique that may be suitable to directly assess vocal cord movement in select patients at high risk for iatrogenic vocal cord palsy following surgery or intubation [169-174]. Variant 7: Unilateral isolated weakness or paralysis of the sternocleidomastoid and trapezius muscles (accessory nerve, CN XI). Initial imaging. The accessory nerve (CN XI) consists of a small cranial root originating from the nucleus ambiguous within the medulla oblongata and a large spinal root originating from the ventral horn of the spinal cord, between the C1 and C5 levels. The two components join and enter the pars vascularis of the jugular foramen [2]. The accessory nerve supplies portions of the sternocleidomastoid muscle and the upper portion of the trapezius muscle. Accessory nerve palsy is clinically manifested by weakness and atrophy of these muscles, causing decreased shoulder abduction, shoulder pain, cosmetic disfiguration, and disability.

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Cranial Neuropathy

Isolated accessory nerve palsy is typically iatrogenic (due to injury from surgery or internal jugular vein cannulation) or may be due to trauma [175]. Accessory nerve palsy can also be accompanied by variable palsies of the glossopharyngeal (CN IX), vagus (CN X), and hypoglossal nerves (CN XII) in combined syndromes, particularly from lesions arising in the brainstem or jugular foramen, as discussed in Variant 9. CT Head There is no relevant literature to support the use of routine CT head alone in the evaluation of unilateral isolated CN XI palsy. CT Maxillofacial There is no relevant literature to support the use of maxillofacial CT in the evaluation of unilateral isolated CN XI palsy. CT Temporal Bone There is no relevant literature to support the use of temporal bone CT in the evaluation of unilateral isolated CN XI palsy. CT Neck Accessory nerve palsy is clinically manifested by weakness and atrophy of the sternocleidomastoid muscle and trapezius muscle and, as an isolated palsy, is typically due to iatrogenic injury. Contrast-enhanced CT neck may be useful to characterize lesions in the carotid space or posterior cervical space along the extracranial course of CN XI, as well as demonstrating atrophy of the trapezius or sternocleidomastoid muscles. MRI offers superior soft tissue contrast to demonstrate denervation changes or directly image features of neuritis and offers the benefit of being able to directly image the intracranial and high cervical portions of the nerve [2]. Imaging protocols should include thin-cut high-resolution bone windows through the posterior skull base. Noncontrast neck CT offers limited evaluation of the neck and may be an alternate option for this clinical scenario. There is no relevant literature to support the use of combined pre- and postcontrast imaging. CTA Head and Neck There is no relevant literature to support the use of CTA in the evaluation of unilateral isolated CN XI palsy.

Cranial Neuropathy. Isolated accessory nerve palsy is typically iatrogenic (due to injury from surgery or internal jugular vein cannulation) or may be due to trauma [175]. Accessory nerve palsy can also be accompanied by variable palsies of the glossopharyngeal (CN IX), vagus (CN X), and hypoglossal nerves (CN XII) in combined syndromes, particularly from lesions arising in the brainstem or jugular foramen, as discussed in Variant 9. CT Head There is no relevant literature to support the use of routine CT head alone in the evaluation of unilateral isolated CN XI palsy. CT Maxillofacial There is no relevant literature to support the use of maxillofacial CT in the evaluation of unilateral isolated CN XI palsy. CT Temporal Bone There is no relevant literature to support the use of temporal bone CT in the evaluation of unilateral isolated CN XI palsy. CT Neck Accessory nerve palsy is clinically manifested by weakness and atrophy of the sternocleidomastoid muscle and trapezius muscle and, as an isolated palsy, is typically due to iatrogenic injury. Contrast-enhanced CT neck may be useful to characterize lesions in the carotid space or posterior cervical space along the extracranial course of CN XI, as well as demonstrating atrophy of the trapezius or sternocleidomastoid muscles. MRI offers superior soft tissue contrast to demonstrate denervation changes or directly image features of neuritis and offers the benefit of being able to directly image the intracranial and high cervical portions of the nerve [2]. Imaging protocols should include thin-cut high-resolution bone windows through the posterior skull base. Noncontrast neck CT offers limited evaluation of the neck and may be an alternate option for this clinical scenario. There is no relevant literature to support the use of combined pre- and postcontrast imaging. CTA Head and Neck There is no relevant literature to support the use of CTA in the evaluation of unilateral isolated CN XI palsy.

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MRA Head and Neck There is no relevant literature to support the use of MRA in the evaluation of vasculature in unilateral isolated CN XI palsy. Cranial Neuropathy Contrast-enhanced modified balanced SSFP sequences and MRA focused on the posterior skull provide detailed imaging of the lower CNs within the jugular foramen and as they exit the skull base [24]. Thin-cut high-resolution heavily T2-weighted imaging combined with MRA provides variable direct visualization of CN XI with the cranial segment identified in 88% of the sides and the spinal segment identified in 93% of the sides in one study [149]. Another study reported lower rates with the spinal root of CN XI visualized in 51% of subjects using contrast- enhanced modified balanced SSFP sequences [24]. Contrast-enhanced modified balanced SSFP sequences and MRA focused on the posterior skull provide detailed imaging of the lower CNs within the jugular foramen and as they exit the skull base [24]. Thin-cut high-resolution heavily T2-weighted imaging combined with MRA provides variable direct visualization of CN XI with the cranial segment identified in 88% of the sides and the spinal segment identified in 93% of the sides in one study [149]. Another study reported lower rates with the spinal root of CN XI visualized in 51% of subjects using contrast- enhanced modified balanced SSFP sequences [24]. MRI offers excellent soft tissue contrast to directly image features of neuritis or nerve sheath tumors as well as fully characterize the carotid space and posterior cervical space [2]. In patients with accessory nerve palsy, atrophy, and denervation, signal changes can be seen in the trapezius muscle on MRI [2,176]. US Neck The accessory nerve can be directly imaged by US within the posterior cervical triangle and can provide a supportive role in the diagnosis of spinal accessory nerve injuries, although sensitivity may be user dependent [177-180]. Variant 8: Unilateral isolated weakness or paralysis of the tongue (hypoglossal nerve, CN XII).

Cranial Neuropathy. MRA Head and Neck There is no relevant literature to support the use of MRA in the evaluation of vasculature in unilateral isolated CN XI palsy. Cranial Neuropathy Contrast-enhanced modified balanced SSFP sequences and MRA focused on the posterior skull provide detailed imaging of the lower CNs within the jugular foramen and as they exit the skull base [24]. Thin-cut high-resolution heavily T2-weighted imaging combined with MRA provides variable direct visualization of CN XI with the cranial segment identified in 88% of the sides and the spinal segment identified in 93% of the sides in one study [149]. Another study reported lower rates with the spinal root of CN XI visualized in 51% of subjects using contrast- enhanced modified balanced SSFP sequences [24]. Contrast-enhanced modified balanced SSFP sequences and MRA focused on the posterior skull provide detailed imaging of the lower CNs within the jugular foramen and as they exit the skull base [24]. Thin-cut high-resolution heavily T2-weighted imaging combined with MRA provides variable direct visualization of CN XI with the cranial segment identified in 88% of the sides and the spinal segment identified in 93% of the sides in one study [149]. Another study reported lower rates with the spinal root of CN XI visualized in 51% of subjects using contrast- enhanced modified balanced SSFP sequences [24]. MRI offers excellent soft tissue contrast to directly image features of neuritis or nerve sheath tumors as well as fully characterize the carotid space and posterior cervical space [2]. In patients with accessory nerve palsy, atrophy, and denervation, signal changes can be seen in the trapezius muscle on MRI [2,176]. US Neck The accessory nerve can be directly imaged by US within the posterior cervical triangle and can provide a supportive role in the diagnosis of spinal accessory nerve injuries, although sensitivity may be user dependent [177-180]. Variant 8: Unilateral isolated weakness or paralysis of the tongue (hypoglossal nerve, CN XII).

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Cranial Neuropathy

Initial imaging. The hypoglossal nerve (CN XII) nucleus arises in the dorsal medulla. The hypoglossal rootlets traverse the premedullary cistern dorsal to the vertebral artery and then form the nerve, which enters the hypoglossal canal where it is surrounded by a venous plexus. The extracranial hypoglossal nerve travels caudally within the carotid space after which it courses anteriorly inferior to the hyoid where it distributes terminal branches providing somatic motor innervation to the intrinsic and extrinsic muscles of the tongue (except the palatoglossus muscle) and the infrahyoid strap muscles via the ansa cervicalis [2,13,181]. Hypoglossal nerve palsy typically presents clinically when a nuclear or infranuclear lesion is present and is characterized by dysarthria and deviation of the tongue to the side of the lesion upon tongue protrusion. Hypoglossal nerve palsy can occur because of injury of the nerve at any point along its course. There are a multitude of causes for hypoglossal nerve palsy including brainstem infarct, demyelinating disease, tumors, vascular lesions, trauma, inflammatory, and infectious processes. Nuclear lesions are usually accompanied by additional neurologic deficits indicative of brainstem involvement. Most hypoglossal nerve palsies are due to neoplasm involving the hypoglossal canal [2,182,183]. Within the extracranial segment, the most common causes of isolated hypoglossal nerve palsy are malignant tumors both along the course of CN XII Cranial Neuropathy in the carotid space and in the sublingual space [184]. Dissection of the internal carotid artery can result in isolated acute CN XII palsy or multiple variable patterns of CN palsies including involvement of CN IX through CN XII [185-187]. Associate denervation signal alterations can be seen on MRI that vary with the duration of the palsy [2,186-188].

Cranial Neuropathy. Initial imaging. The hypoglossal nerve (CN XII) nucleus arises in the dorsal medulla. The hypoglossal rootlets traverse the premedullary cistern dorsal to the vertebral artery and then form the nerve, which enters the hypoglossal canal where it is surrounded by a venous plexus. The extracranial hypoglossal nerve travels caudally within the carotid space after which it courses anteriorly inferior to the hyoid where it distributes terminal branches providing somatic motor innervation to the intrinsic and extrinsic muscles of the tongue (except the palatoglossus muscle) and the infrahyoid strap muscles via the ansa cervicalis [2,13,181]. Hypoglossal nerve palsy typically presents clinically when a nuclear or infranuclear lesion is present and is characterized by dysarthria and deviation of the tongue to the side of the lesion upon tongue protrusion. Hypoglossal nerve palsy can occur because of injury of the nerve at any point along its course. There are a multitude of causes for hypoglossal nerve palsy including brainstem infarct, demyelinating disease, tumors, vascular lesions, trauma, inflammatory, and infectious processes. Nuclear lesions are usually accompanied by additional neurologic deficits indicative of brainstem involvement. Most hypoglossal nerve palsies are due to neoplasm involving the hypoglossal canal [2,182,183]. Within the extracranial segment, the most common causes of isolated hypoglossal nerve palsy are malignant tumors both along the course of CN XII Cranial Neuropathy in the carotid space and in the sublingual space [184]. Dissection of the internal carotid artery can result in isolated acute CN XII palsy or multiple variable patterns of CN palsies including involvement of CN IX through CN XII [185-187]. Associate denervation signal alterations can be seen on MRI that vary with the duration of the palsy [2,186-188].

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Hypoglossal nerve palsy can also be accompanied by variable palsies of the glossopharyngeal (CN IX), vagus (CN X), and accessory nerves (CN XI) in combined syndromes, particularly from lesions arising in the brainstem or jugular foramen, as discussed in Variant 9 [183]. CT Head There is no relevant literature to support the use of routine CT head alone in the initial evaluation of unilateral isolated CN XII palsy. CT Maxillofacial There is no relevant literature to support the use of maxillofacial CT in the initial evaluation of unilateral isolated CN XII palsy. CT Temporal Bone There is no relevant literature to support the use of temporal bone CT in the initial evaluation of unilateral isolated CN XII palsy. CT Neck Evaluation of the entire course of the hypoglossal nerve is required with a hypoglossal nerve palsy. MRI is useful for evaluating hypoglossal nerve palsy, directly imaging the brainstem, the intracranial and skull base segments of the hypoglossal nerve and assessing for possible lesions along the extracranial segments of the nerve while providing improved soft tissue contrast [5,13,181,183,189]. The extracranial segment of the hypoglossal nerve within the suprahyoid neck is difficult to see with MRI and CT and inferred by knowledge of the nerve course and surrounding anatomy. Neck CT provides complementary information to MRI, characterizing the osseous integrity of the hypoglossal canal and surrounding skull base [183]. Imaging protocols should include thin-cut high-resolution bone windows through the posterior skull base. Contrast should be administered, because tumors are the most common cause of isolated hypoglossal nerve palsy in this segment. Noncontrast CT may also be an alternate option for this clinical scenario. There is no relevant literature to support the use of combined pre- and postcontrast imaging.

Cranial Neuropathy. Hypoglossal nerve palsy can also be accompanied by variable palsies of the glossopharyngeal (CN IX), vagus (CN X), and accessory nerves (CN XI) in combined syndromes, particularly from lesions arising in the brainstem or jugular foramen, as discussed in Variant 9 [183]. CT Head There is no relevant literature to support the use of routine CT head alone in the initial evaluation of unilateral isolated CN XII palsy. CT Maxillofacial There is no relevant literature to support the use of maxillofacial CT in the initial evaluation of unilateral isolated CN XII palsy. CT Temporal Bone There is no relevant literature to support the use of temporal bone CT in the initial evaluation of unilateral isolated CN XII palsy. CT Neck Evaluation of the entire course of the hypoglossal nerve is required with a hypoglossal nerve palsy. MRI is useful for evaluating hypoglossal nerve palsy, directly imaging the brainstem, the intracranial and skull base segments of the hypoglossal nerve and assessing for possible lesions along the extracranial segments of the nerve while providing improved soft tissue contrast [5,13,181,183,189]. The extracranial segment of the hypoglossal nerve within the suprahyoid neck is difficult to see with MRI and CT and inferred by knowledge of the nerve course and surrounding anatomy. Neck CT provides complementary information to MRI, characterizing the osseous integrity of the hypoglossal canal and surrounding skull base [183]. Imaging protocols should include thin-cut high-resolution bone windows through the posterior skull base. Contrast should be administered, because tumors are the most common cause of isolated hypoglossal nerve palsy in this segment. Noncontrast CT may also be an alternate option for this clinical scenario. There is no relevant literature to support the use of combined pre- and postcontrast imaging.

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Cranial Neuropathy

For detecting hypoglossal canal invasion by glomus tumors, CT had a sensitivity and specificity of 87.5% and 66.7%, respectively, compared with MRI which had a sensitivity of 100% and a specificity of 59% [183]. CTA Head and Neck When dissection of the internal carotid artery is clinically suspected as a cause of acute isolated CN XII palsy, CTA may be useful to evaluate for dissection, particularly in the emergent setting. In a study comparing CTA with conventional angiography, CTA had a sensitivity of 66% when evaluating for blunt carotid vascular injury, with most false-negatives representing low grade injuries [190]. In a comparative study, multidetector CT/CTA demonstrated more features of cervical artery (internal carotid and vertebral arteries) dissection compared with MRI/MRA. There was no significant reader preference for MRI/MRA compared with CT/CTA when evaluating for internal carotid artery dissection. MRI/MRA provided additional characterization of ischemic complications [191]. In a retrospective review of the literature comparing test performance of MRI/MRA with CTA in the assessment of cervicocephalic arterial dissection with a reference standard of catheter angiography, the authors report MRI sensitivities and specificities of 50% to 79% and 67% to 99%, respectively, and CTA sensitivities and specificities of 51% to 98% and 67% to 100%, respectively (based on prospective studies) [192]. The authors concluded that the test characteristics of MRI/MRA and CTA for diagnosis of cervicocephalic arterial dissection were similar and study selection should be based on individual factors including urgency of imaging. A limitation of the literature assessing MRA and CTA for dissection is that most studies evaluate test performance in the clinical setting of traumatic dissection rather than spontaneous dissection. CTA is often used as a primary screening tool when carotid dissection is suspected in the emergent setting [190].

Cranial Neuropathy. For detecting hypoglossal canal invasion by glomus tumors, CT had a sensitivity and specificity of 87.5% and 66.7%, respectively, compared with MRI which had a sensitivity of 100% and a specificity of 59% [183]. CTA Head and Neck When dissection of the internal carotid artery is clinically suspected as a cause of acute isolated CN XII palsy, CTA may be useful to evaluate for dissection, particularly in the emergent setting. In a study comparing CTA with conventional angiography, CTA had a sensitivity of 66% when evaluating for blunt carotid vascular injury, with most false-negatives representing low grade injuries [190]. In a comparative study, multidetector CT/CTA demonstrated more features of cervical artery (internal carotid and vertebral arteries) dissection compared with MRI/MRA. There was no significant reader preference for MRI/MRA compared with CT/CTA when evaluating for internal carotid artery dissection. MRI/MRA provided additional characterization of ischemic complications [191]. In a retrospective review of the literature comparing test performance of MRI/MRA with CTA in the assessment of cervicocephalic arterial dissection with a reference standard of catheter angiography, the authors report MRI sensitivities and specificities of 50% to 79% and 67% to 99%, respectively, and CTA sensitivities and specificities of 51% to 98% and 67% to 100%, respectively (based on prospective studies) [192]. The authors concluded that the test characteristics of MRI/MRA and CTA for diagnosis of cervicocephalic arterial dissection were similar and study selection should be based on individual factors including urgency of imaging. A limitation of the literature assessing MRA and CTA for dissection is that most studies evaluate test performance in the clinical setting of traumatic dissection rather than spontaneous dissection. CTA is often used as a primary screening tool when carotid dissection is suspected in the emergent setting [190].

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Cranial Neuropathy

FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of FDG-PET/CT skull base to mid-thigh in the initial evaluation of unilateral isolated CN XII palsy. Cranial Neuropathy MRA Head and Neck When dissection of the internal carotid artery is suspected as a cause of acute isolated CN XII palsy, MRA may be useful to evaluate for dissection. In a retrospective review of the literature comparing test performance of MRI/MRA with CTA in the assessment of cervicocephalic arterial dissection with a reference standard of catheter angiography, the authors report MRI sensitivities and specificities of 50% to 79% and 67% to 99%, respectively, and CTA sensitivities and specificities of 51% to 98% and 67% to 100%, respectively (based on prospective studies) [192]. The authors concluded that the test characteristics of MRI/MRA and CTA for diagnosis of cervicocephalic arterial dissection were similar and study selection should be based on individual factors including urgency of imaging. In another comparative study, multidetector CT/CTA demonstrated more features of cervical artery (internal carotid and vertebral arteries) dissection compared with MRI/MRA. There was no significant reader preference for MRI/MRA compared with CT/CTA when evaluating for internal carotid artery dissection. MRI/MRA provided additional characterization of ischemic complications [191]. A limitation of the literature assessing MRA and CTA for dissection is that most studies evaluate test performance in the clinical setting of traumatic dissection rather than spontaneous dissection. CTA is often used as a primary screening tool when carotid dissection is suspected in the emergent setting [190]. MRI had greater sensitivity (100%) but lower specificity (59%) for detecting hypoglossal canal invasion by glomus jugulare tumors when compared with CT (sensitivity of 87.5% and specificity of 66.7%) [183].

Cranial Neuropathy. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of FDG-PET/CT skull base to mid-thigh in the initial evaluation of unilateral isolated CN XII palsy. Cranial Neuropathy MRA Head and Neck When dissection of the internal carotid artery is suspected as a cause of acute isolated CN XII palsy, MRA may be useful to evaluate for dissection. In a retrospective review of the literature comparing test performance of MRI/MRA with CTA in the assessment of cervicocephalic arterial dissection with a reference standard of catheter angiography, the authors report MRI sensitivities and specificities of 50% to 79% and 67% to 99%, respectively, and CTA sensitivities and specificities of 51% to 98% and 67% to 100%, respectively (based on prospective studies) [192]. The authors concluded that the test characteristics of MRI/MRA and CTA for diagnosis of cervicocephalic arterial dissection were similar and study selection should be based on individual factors including urgency of imaging. In another comparative study, multidetector CT/CTA demonstrated more features of cervical artery (internal carotid and vertebral arteries) dissection compared with MRI/MRA. There was no significant reader preference for MRI/MRA compared with CT/CTA when evaluating for internal carotid artery dissection. MRI/MRA provided additional characterization of ischemic complications [191]. A limitation of the literature assessing MRA and CTA for dissection is that most studies evaluate test performance in the clinical setting of traumatic dissection rather than spontaneous dissection. CTA is often used as a primary screening tool when carotid dissection is suspected in the emergent setting [190]. MRI had greater sensitivity (100%) but lower specificity (59%) for detecting hypoglossal canal invasion by glomus jugulare tumors when compared with CT (sensitivity of 87.5% and specificity of 66.7%) [183].

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Denervation injury changes that occur within the tongue in the setting of hypoglossal nerve palsy vary with acuity and can be detected on MRI and CT, with MRI providing better soft tissue contrast [186-188]. Thin-cut heavily T2-weighted contrast- enhanced modified balanced SSFP sequences and contrast-enhanced MRA focused on the posterior skull provide detailed imaging of the lower nerves with 90% to 100% of imaged CN XII visible [24]. MRI had greater sensitivity (100%) but lower specificity (59%) for detecting hypoglossal canal invasion by glomus jugulare tumors when compared with CT (sensitivity of 87.5% and specificity of 66.7%) [183]. Denervation injury changes that occur within the tongue in the setting of hypoglossal nerve palsy vary with acuity and can be detected on MRI and CT, with MRI providing better soft tissue contrast [186-188]. Thin-cut heavily T2-weighted contrast- enhanced modified balanced SSFP sequences and contrast-enhanced MRA focused on the posterior skull provide detailed imaging of the lower nerves with 90% to 100% of imaged CN XII visible [24]. Cranial Neuropathy US Neck There is no relevant literature to support the use of US neck in the initial evaluation of unilateral isolated CN XII palsy. Variant 9: Multiple different lower cranial nerve palsies or combined lower cranial nerve syndromes (CN IX-XII). Initial imaging. The medulla oblongata joins the pons to the spinal cord and is composed of a ventral portion and a dorsal tegmentum. The ventral portion contains the pyramids and olives, and the dorsal tegmentum contains CN IX through CN XII nuclei along with the white matter sensory tracts. Vascular supply to the medulla is from the anterior spinal artery, branches of the vertebral arteries, and the posterior inferior cerebellar arteries [1,131]. Outside the brainstem, CN IX through CN XI traverse the jugular foramen, and CN XII traverses the hypoglossal canal in the posterior skull base before extending caudally into the neck.

Cranial Neuropathy. Denervation injury changes that occur within the tongue in the setting of hypoglossal nerve palsy vary with acuity and can be detected on MRI and CT, with MRI providing better soft tissue contrast [186-188]. Thin-cut heavily T2-weighted contrast- enhanced modified balanced SSFP sequences and contrast-enhanced MRA focused on the posterior skull provide detailed imaging of the lower nerves with 90% to 100% of imaged CN XII visible [24]. MRI had greater sensitivity (100%) but lower specificity (59%) for detecting hypoglossal canal invasion by glomus jugulare tumors when compared with CT (sensitivity of 87.5% and specificity of 66.7%) [183]. Denervation injury changes that occur within the tongue in the setting of hypoglossal nerve palsy vary with acuity and can be detected on MRI and CT, with MRI providing better soft tissue contrast [186-188]. Thin-cut heavily T2-weighted contrast- enhanced modified balanced SSFP sequences and contrast-enhanced MRA focused on the posterior skull provide detailed imaging of the lower nerves with 90% to 100% of imaged CN XII visible [24]. Cranial Neuropathy US Neck There is no relevant literature to support the use of US neck in the initial evaluation of unilateral isolated CN XII palsy. Variant 9: Multiple different lower cranial nerve palsies or combined lower cranial nerve syndromes (CN IX-XII). Initial imaging. The medulla oblongata joins the pons to the spinal cord and is composed of a ventral portion and a dorsal tegmentum. The ventral portion contains the pyramids and olives, and the dorsal tegmentum contains CN IX through CN XII nuclei along with the white matter sensory tracts. Vascular supply to the medulla is from the anterior spinal artery, branches of the vertebral arteries, and the posterior inferior cerebellar arteries [1,131]. Outside the brainstem, CN IX through CN XI traverse the jugular foramen, and CN XII traverses the hypoglossal canal in the posterior skull base before extending caudally into the neck.

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