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acrac_69359_2

Suspected Spine Trauma PCAs

Clinical examination has a low to very low sensitivity for identifying thoracolumbar spine injuries [16-18]. Therefore, a low threshold should be maintained for screening the thoracolumbar spine with imaging in the setting of blunt trauma, particularly in older patients, who are at increased risk for spine fractures occurring in the setting of low-energy trauma, such as a fall from standing (ie, fragility fractures), which are due to diminished bone mineralization commonly present in older patient populations. A low threshold for imaging of the thoracolumbar Suspected Spine Trauma spine should also be maintained for patients with disease processes known to cause spine rigidity, such as diffuse idiopathic skeletal hyperostosis or ankylosing spondylitis. Fractures found at one level of the spine are associated with injury at other noncontiguous levels of the spine in an estimated 20% of trauma patients [26,27]. Therefore, screening of the entire cervical spine should be considered whenever an injury of the thoracolumbar spine is identified in the setting of blunt trauma. Cervical, thoracic, and lumbar spine CT reconstructions can be performed from concurrently obtained neck CT angiograms, CT imaging of the thorax, or abdomen and pelvis in trauma patients who are also imaged for suspected soft-tissue or vascular injuries, providing the same image quality as a dedicated examination without Suspected Spine Trauma CT Myelography Cervical Spine There is no role for CT myelography in the initial assessment of patients with low risk for cervical spine injury. CT Cervical Spine CT is excellent at identifying cervical spine injuries. CT is considered the gold standard for identification of cervical spine fractures, outperforming radiographs in identification of cervical spine fractures in high-, moderate- and low-risk stratifications [31]. CT is inferior to MRI in identification of many soft-tissue injuries, such as epidural hematoma, cord contusion, and ligament sprains [37-42].

Suspected Spine Trauma PCAs. Clinical examination has a low to very low sensitivity for identifying thoracolumbar spine injuries [16-18]. Therefore, a low threshold should be maintained for screening the thoracolumbar spine with imaging in the setting of blunt trauma, particularly in older patients, who are at increased risk for spine fractures occurring in the setting of low-energy trauma, such as a fall from standing (ie, fragility fractures), which are due to diminished bone mineralization commonly present in older patient populations. A low threshold for imaging of the thoracolumbar Suspected Spine Trauma spine should also be maintained for patients with disease processes known to cause spine rigidity, such as diffuse idiopathic skeletal hyperostosis or ankylosing spondylitis. Fractures found at one level of the spine are associated with injury at other noncontiguous levels of the spine in an estimated 20% of trauma patients [26,27]. Therefore, screening of the entire cervical spine should be considered whenever an injury of the thoracolumbar spine is identified in the setting of blunt trauma. Cervical, thoracic, and lumbar spine CT reconstructions can be performed from concurrently obtained neck CT angiograms, CT imaging of the thorax, or abdomen and pelvis in trauma patients who are also imaged for suspected soft-tissue or vascular injuries, providing the same image quality as a dedicated examination without Suspected Spine Trauma CT Myelography Cervical Spine There is no role for CT myelography in the initial assessment of patients with low risk for cervical spine injury. CT Cervical Spine CT is excellent at identifying cervical spine injuries. CT is considered the gold standard for identification of cervical spine fractures, outperforming radiographs in identification of cervical spine fractures in high-, moderate- and low-risk stratifications [31]. CT is inferior to MRI in identification of many soft-tissue injuries, such as epidural hematoma, cord contusion, and ligament sprains [37-42].

69359

acrac_69359_3

Suspected Spine Trauma PCAs

However, MRI occasionally identifies cervical spine instability that was not appreciable on CT. Less than 1% of unexaminable patients will have evidence of cervical spine instability on MRI that is not appreciated on CT [40,41,43-48]. CT may be adequate for excluding clinically significant cervical spine injury in patients without neurologic symptoms even in the setting of neck tenderness [49]. CT with IV contrast does not aid in detection of cervical spine injury. CTA Head and Neck CT is the gold standard for identifying cervical spine fractures. CT during arterial phase of IV contrast administration (ie, CT angiography [CTA]) provides the added benefit of excellent visualization of arterial vasculature for assessment of arterial injury. CTA is inferior to catheter angiography in identification of cervical arterial injury [50,51]. Using catheter angiography as a gold standard, recent studies using multislice CT scanners with 16 or more detector rows have found CTA to have a reported sensitivity of 41% to 98% and specificity of 81% to 100% for identifying cervical arterial injury [43,44]. However, CTA has been shown to identify all clinically significant cervical arterial injuries [52,53], and using catheter angiography as the gold standard inherently places CTA at a disadvantage when comparing the two modalities, since catheter angiography arterial injury [50,54] is assumed to be 100% sensitive and 100% specific. CTA does expose patients to potential adverse events associated with IV contrast and can make diagnosis of subtle cervical spine fractures more challenging because of the superimposition of high attenuating contrast on the imaging field if an unenhanced examination was not performed before giving contrast. Dual-energy CT may also be utilized to remove contrast enhancement; Suspected Spine Trauma however, dual-energy CT is not widely available. CTA imaging is best reserved for patients with a high index of suspicion for cervical arterial injury.

Suspected Spine Trauma PCAs. However, MRI occasionally identifies cervical spine instability that was not appreciable on CT. Less than 1% of unexaminable patients will have evidence of cervical spine instability on MRI that is not appreciated on CT [40,41,43-48]. CT may be adequate for excluding clinically significant cervical spine injury in patients without neurologic symptoms even in the setting of neck tenderness [49]. CT with IV contrast does not aid in detection of cervical spine injury. CTA Head and Neck CT is the gold standard for identifying cervical spine fractures. CT during arterial phase of IV contrast administration (ie, CT angiography [CTA]) provides the added benefit of excellent visualization of arterial vasculature for assessment of arterial injury. CTA is inferior to catheter angiography in identification of cervical arterial injury [50,51]. Using catheter angiography as a gold standard, recent studies using multislice CT scanners with 16 or more detector rows have found CTA to have a reported sensitivity of 41% to 98% and specificity of 81% to 100% for identifying cervical arterial injury [43,44]. However, CTA has been shown to identify all clinically significant cervical arterial injuries [52,53], and using catheter angiography as the gold standard inherently places CTA at a disadvantage when comparing the two modalities, since catheter angiography arterial injury [50,54] is assumed to be 100% sensitive and 100% specific. CTA does expose patients to potential adverse events associated with IV contrast and can make diagnosis of subtle cervical spine fractures more challenging because of the superimposition of high attenuating contrast on the imaging field if an unenhanced examination was not performed before giving contrast. Dual-energy CT may also be utilized to remove contrast enhancement; Suspected Spine Trauma however, dual-energy CT is not widely available. CTA imaging is best reserved for patients with a high index of suspicion for cervical arterial injury.

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acrac_69359_4

Suspected Spine Trauma PCAs

MRI Cervical Spine MRI is generally considered inferior to CT in identifying fractures. MRI is superior to CT in identifying soft- tissue injuries of the cervical spine [37-42]. Trauma patients with negative cervical spine CT will have traumatic soft-tissue injuries identified on MRI in 5% to 24% of cases [39-41,44,45,47,48]. The identification of these soft- tissue injuries often results in extended placement of a cervical collar. However, in the absence of clinical evidence of neurologic or unstable ligament injury, MRI has a very low probability of identifying a soft-tissue injury requiring surgical treatment that is not apparent on CT [40,41,43-48,55]. Recent prospective multicenter trials suggest that MRI has a role in evaluating patients who have a negative cervical spine CT. The Western Trauma Association Multi-Institutional trial reported that CT was effective for ruling out clinically significant injury with a sensitivity of 98.5%. A small but clinically significant incidence of a missed injury was noted, and further imaging with MRI is warranted [56]. The prospective Research Consortium of New England Centers for Trauma (ReCONECT) trial studied 767 patients who had a negative cervical spine CT and went on to MRI because of cervicalgia (43.0%), inability to evaluate the cervical spine on physical examination (44.1%), or both (9.4%). MRI was abnormal in 23.6% of all patients, including ligamentous injury (16.6%), soft-tissue swelling (4.3%), vertebral disc injury (1.4%), and dural hematomas (1.3%). The patients with abnormal MRI were less likely to have their cervical collar removed than those with normal MRI (13.3% versus 88.1%). Eleven patients underwent cervical spine surgery after the MRI results. The clinical significance of these abnormal MRI findings could not be determined from this study group [55]. MRA Neck There is no role for MR angiography (MRA) in the initial assessment of patients with low risk for cervical spine injury.

Suspected Spine Trauma PCAs. MRI Cervical Spine MRI is generally considered inferior to CT in identifying fractures. MRI is superior to CT in identifying soft- tissue injuries of the cervical spine [37-42]. Trauma patients with negative cervical spine CT will have traumatic soft-tissue injuries identified on MRI in 5% to 24% of cases [39-41,44,45,47,48]. The identification of these soft- tissue injuries often results in extended placement of a cervical collar. However, in the absence of clinical evidence of neurologic or unstable ligament injury, MRI has a very low probability of identifying a soft-tissue injury requiring surgical treatment that is not apparent on CT [40,41,43-48,55]. Recent prospective multicenter trials suggest that MRI has a role in evaluating patients who have a negative cervical spine CT. The Western Trauma Association Multi-Institutional trial reported that CT was effective for ruling out clinically significant injury with a sensitivity of 98.5%. A small but clinically significant incidence of a missed injury was noted, and further imaging with MRI is warranted [56]. The prospective Research Consortium of New England Centers for Trauma (ReCONECT) trial studied 767 patients who had a negative cervical spine CT and went on to MRI because of cervicalgia (43.0%), inability to evaluate the cervical spine on physical examination (44.1%), or both (9.4%). MRI was abnormal in 23.6% of all patients, including ligamentous injury (16.6%), soft-tissue swelling (4.3%), vertebral disc injury (1.4%), and dural hematomas (1.3%). The patients with abnormal MRI were less likely to have their cervical collar removed than those with normal MRI (13.3% versus 88.1%). Eleven patients underwent cervical spine surgery after the MRI results. The clinical significance of these abnormal MRI findings could not be determined from this study group [55]. MRA Neck There is no role for MR angiography (MRA) in the initial assessment of patients with low risk for cervical spine injury.

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acrac_69359_5

Suspected Spine Trauma PCAs

Arteriography Cervicocerebral There is no role for arteriography in the initial assessment of patients with low risk for cervical spine injury. Variant 2: Age greater than or equal to 16 years. Suspected acute cervical spine blunt trauma. Imaging indicated by NEXUS or CCR clinical criteria. Initial imaging. The high sensitivity of both the NEXUS criteria and CCR for detecting significant cervical spine injury comes at a cost of both criteria having a very low specificity for significant cervical spine injury. NEXUS has a reported sensitivity of 81.2% to 99.6% with a specificity of 12.9% to 45.8% [4,11]. The original study of CCR by Stiell et al [5] reported a sensitivity of 100%, which was confirmed in later studies by Duane et al [11,12]. In head-to-head comparisons, specificity of CCR has been reported from 0.6% to 42.5% [5,7,11,12], overlapping that of the NEXUS criteria. Both of these criteria are widely used for clinical screening for cervical spine injury, and it is generally accepted that patients who do not meet either the NEXUS or CCR criteria do not require imaging evaluation for cervical spine injury. CT Myelography Cervical Spine There is no role for CT myelography in the initial assessment of patients with suspected cervical spine injury. Suspected Spine Trauma CT Cervical Spine CT is excellent at identifying cervical spine injuries. CT is considered the gold standard for identification of cervical spine fractures, outperforming radiographs in identification of cervical spine fractures in high-, moderate- and low-risk stratifications [31]. CT is inferior to MRI in identification of many soft-tissue injuries, such as epidural hematoma, cord contusion, and ligament sprains [37-42]. However, MRI occasionally identifies cervical spine instability that was not appreciable on CT. Less than 1% of unexaminable patients will have evidence of cervical spine instability on MRI that is not appreciated on CT [40,41,43-48].

Suspected Spine Trauma PCAs. Arteriography Cervicocerebral There is no role for arteriography in the initial assessment of patients with low risk for cervical spine injury. Variant 2: Age greater than or equal to 16 years. Suspected acute cervical spine blunt trauma. Imaging indicated by NEXUS or CCR clinical criteria. Initial imaging. The high sensitivity of both the NEXUS criteria and CCR for detecting significant cervical spine injury comes at a cost of both criteria having a very low specificity for significant cervical spine injury. NEXUS has a reported sensitivity of 81.2% to 99.6% with a specificity of 12.9% to 45.8% [4,11]. The original study of CCR by Stiell et al [5] reported a sensitivity of 100%, which was confirmed in later studies by Duane et al [11,12]. In head-to-head comparisons, specificity of CCR has been reported from 0.6% to 42.5% [5,7,11,12], overlapping that of the NEXUS criteria. Both of these criteria are widely used for clinical screening for cervical spine injury, and it is generally accepted that patients who do not meet either the NEXUS or CCR criteria do not require imaging evaluation for cervical spine injury. CT Myelography Cervical Spine There is no role for CT myelography in the initial assessment of patients with suspected cervical spine injury. Suspected Spine Trauma CT Cervical Spine CT is excellent at identifying cervical spine injuries. CT is considered the gold standard for identification of cervical spine fractures, outperforming radiographs in identification of cervical spine fractures in high-, moderate- and low-risk stratifications [31]. CT is inferior to MRI in identification of many soft-tissue injuries, such as epidural hematoma, cord contusion, and ligament sprains [37-42]. However, MRI occasionally identifies cervical spine instability that was not appreciable on CT. Less than 1% of unexaminable patients will have evidence of cervical spine instability on MRI that is not appreciated on CT [40,41,43-48].

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acrac_69359_6

Suspected Spine Trauma PCAs

Several recent papers conclude that CT may be adequate for excluding clinically significant cervical spine injury in patients without neurologic symptoms, even in the setting of neck tenderness [49]. However, recent multicenter trials suggest that CT alone is not sufficient and MRI may be warranted in some patients (see MRI section below). CT with IV contrast does not aid in detection of cervical spine injury. CTA Head and Neck CT is the gold standard for identifying cervical spine fractures. CT during arterial phase of IV contrast administration (CTA) provides the added benefit of excellent visualization of arterial vasculature for assessment of arterial injury. CTA is inferior to catheter angiography in identification of cervical arterial injury [50,51]. However, CTA has been shown to identify all clinically significant cervical arterial injuries [52,53], and using catheter angiography as the gold standard inherently places CTA at a disadvantage when comparing the two modalities since catheter angiography is assumed to be 100% sensitive and 100% specific. CTA does expose patients to potential adverse events associated with IV contrast and can make diagnosis of subtle cervical spine fractures more challenging because of the superimposition of high attenuating contrast on the imaging field if an unenhanced examination was not performed before giving contrast. Dual-energy CT may also be utilized to remove contrast enhancement; however, dual-energy CT is not widely available. CTA imaging is best reserved for patients with a high index of suspicion for cervical arterial injury. MRI Cervical Spine MRI is generally considered inferior to CT in identifying fractures. MRI is superior to CT in identifying soft- tissue injuries of the cervical spine [37-42]. MRI will identify soft-tissue injuries in 5% to 24% of blunt trauma patients with negative cervical spine CT [39-41,44,45,47,48,55]. The identification of these soft-tissue injuries often results in extended placement of a cervical collar.

Suspected Spine Trauma PCAs. Several recent papers conclude that CT may be adequate for excluding clinically significant cervical spine injury in patients without neurologic symptoms, even in the setting of neck tenderness [49]. However, recent multicenter trials suggest that CT alone is not sufficient and MRI may be warranted in some patients (see MRI section below). CT with IV contrast does not aid in detection of cervical spine injury. CTA Head and Neck CT is the gold standard for identifying cervical spine fractures. CT during arterial phase of IV contrast administration (CTA) provides the added benefit of excellent visualization of arterial vasculature for assessment of arterial injury. CTA is inferior to catheter angiography in identification of cervical arterial injury [50,51]. However, CTA has been shown to identify all clinically significant cervical arterial injuries [52,53], and using catheter angiography as the gold standard inherently places CTA at a disadvantage when comparing the two modalities since catheter angiography is assumed to be 100% sensitive and 100% specific. CTA does expose patients to potential adverse events associated with IV contrast and can make diagnosis of subtle cervical spine fractures more challenging because of the superimposition of high attenuating contrast on the imaging field if an unenhanced examination was not performed before giving contrast. Dual-energy CT may also be utilized to remove contrast enhancement; however, dual-energy CT is not widely available. CTA imaging is best reserved for patients with a high index of suspicion for cervical arterial injury. MRI Cervical Spine MRI is generally considered inferior to CT in identifying fractures. MRI is superior to CT in identifying soft- tissue injuries of the cervical spine [37-42]. MRI will identify soft-tissue injuries in 5% to 24% of blunt trauma patients with negative cervical spine CT [39-41,44,45,47,48,55]. The identification of these soft-tissue injuries often results in extended placement of a cervical collar.

69359

acrac_69359_7

Suspected Spine Trauma PCAs

However, in the absence of clinical evidence of neurologic or unstable ligament injury, MRI has a low probability of identifying a soft-tissue injury requiring surgical treatment that is not apparent on CT [40,41,43-48,55]. Recent prospective multicenter trials suggest that MRI has a role in evaluating patients who have a negative cervical spine CT. The Western Trauma Association Multi-Institutional trial reported that CT was effective for ruling out clinically significant injury with a sensitivity of 98.5%. A small but clinically significant incidence of a missed injury was noted, and further imaging with MRI is warranted [56]. The prospective ReCONECT trial studied 767 patients who had a negative cervical spine CT and went on to MRI because of cervicalgia (43.0%), inability to evaluate the cervical spine on physical examination (44.1%), or both (9.4%). MRI was abnormal in 23.6% of all patients, including ligamentous injury (16.6%), soft-tissue swelling (4.3%), vertebral disc injury (1.4%), and dural hematomas (1.3%). The patients with abnormal MRI were less likely to have their cervical collar removed than those with normal MRI (13.3% versus 88.1%). Eleven patients underwent cervical spine surgery after the MRI results. The clinical significance of these abnormal MRI findings could not be determined from this study group [55]. MRA Neck There is no role for MRA in the initial assessment of patients with suspected cervical spine injury. Arteriography Cervicocerebral There is no role for arteriography in the initial assessment of patients with suspected cervical spine injury. Variant 3: Age greater than or equal to 16 years. Suspected acute cervical spine blunt trauma. Confirmed or suspected cervical spinal cord or nerve root injury, with or without traumatic injury identified on cervical CT. Next imaging study. Cervical spine CT is the preferred modality for the initial assessment of cervical spine injury.

Suspected Spine Trauma PCAs. However, in the absence of clinical evidence of neurologic or unstable ligament injury, MRI has a low probability of identifying a soft-tissue injury requiring surgical treatment that is not apparent on CT [40,41,43-48,55]. Recent prospective multicenter trials suggest that MRI has a role in evaluating patients who have a negative cervical spine CT. The Western Trauma Association Multi-Institutional trial reported that CT was effective for ruling out clinically significant injury with a sensitivity of 98.5%. A small but clinically significant incidence of a missed injury was noted, and further imaging with MRI is warranted [56]. The prospective ReCONECT trial studied 767 patients who had a negative cervical spine CT and went on to MRI because of cervicalgia (43.0%), inability to evaluate the cervical spine on physical examination (44.1%), or both (9.4%). MRI was abnormal in 23.6% of all patients, including ligamentous injury (16.6%), soft-tissue swelling (4.3%), vertebral disc injury (1.4%), and dural hematomas (1.3%). The patients with abnormal MRI were less likely to have their cervical collar removed than those with normal MRI (13.3% versus 88.1%). Eleven patients underwent cervical spine surgery after the MRI results. The clinical significance of these abnormal MRI findings could not be determined from this study group [55]. MRA Neck There is no role for MRA in the initial assessment of patients with suspected cervical spine injury. Arteriography Cervicocerebral There is no role for arteriography in the initial assessment of patients with suspected cervical spine injury. Variant 3: Age greater than or equal to 16 years. Suspected acute cervical spine blunt trauma. Confirmed or suspected cervical spinal cord or nerve root injury, with or without traumatic injury identified on cervical CT. Next imaging study. Cervical spine CT is the preferred modality for the initial assessment of cervical spine injury.

69359

acrac_69359_8

Suspected Spine Trauma PCAs

However, CT is significantly inferior to MRI in identifying many soft-tissue pathologies, such as spinal cord contusion, epidural hematoma, and nerve root avulsions, that can cause neurologic deficits and require surgical intervention [40,41,43,57]. Therefore, CT should not be considered adequate for excluding significant soft-tissue pathology in patients presenting with signs or symptoms of cervical spinal cord or nerve root injury. Suspected Spine Trauma Radiography Cervical Spine While radiographs may play a role in the initial assessment of cervical spine injury, there is no role for radiographs in further assessment of cervical neurologic injury that is due to the poor sensitivity and specificity of cervical radiographs in assessing soft-tissue injury. CT Myelography Cervical Spine CT myelography can be performed to assess for traumatic spinal canal narrowing that is due to disc herniation or epidural hematoma and to assess for preganglionic nerve root avulsions. However, as with conventional CT, CT myelography is inferior to MRI in assessing spinal cord contusion, spinal cord hemorrhage, and postganglionic nerve root injuries [40,41,43,57]. Performance of cervical CT myelogram can also be technically challenging, particularly in patients with suspected unstable cervical spine injury. CTA Head and Neck There is no role for CTA in the assessment of cervical spinal cord or nerve root injury. If there is concern for arterial dissection that is due to the mechanism of injury, please refer to Variant 5. In the subacute and chronic stages after cord trauma, MRI can help define the extent of cord injury. This is particularly important in patients who suffer late deterioration, which is sometimes caused by treatable etiologies, such as development or enlargement of intramedullary cavities. MRA Neck There is no role for MRA in the evaluation of suspected traumatic cervical myelopathy or radiculopathy [59].

Suspected Spine Trauma PCAs. However, CT is significantly inferior to MRI in identifying many soft-tissue pathologies, such as spinal cord contusion, epidural hematoma, and nerve root avulsions, that can cause neurologic deficits and require surgical intervention [40,41,43,57]. Therefore, CT should not be considered adequate for excluding significant soft-tissue pathology in patients presenting with signs or symptoms of cervical spinal cord or nerve root injury. Suspected Spine Trauma Radiography Cervical Spine While radiographs may play a role in the initial assessment of cervical spine injury, there is no role for radiographs in further assessment of cervical neurologic injury that is due to the poor sensitivity and specificity of cervical radiographs in assessing soft-tissue injury. CT Myelography Cervical Spine CT myelography can be performed to assess for traumatic spinal canal narrowing that is due to disc herniation or epidural hematoma and to assess for preganglionic nerve root avulsions. However, as with conventional CT, CT myelography is inferior to MRI in assessing spinal cord contusion, spinal cord hemorrhage, and postganglionic nerve root injuries [40,41,43,57]. Performance of cervical CT myelogram can also be technically challenging, particularly in patients with suspected unstable cervical spine injury. CTA Head and Neck There is no role for CTA in the assessment of cervical spinal cord or nerve root injury. If there is concern for arterial dissection that is due to the mechanism of injury, please refer to Variant 5. In the subacute and chronic stages after cord trauma, MRI can help define the extent of cord injury. This is particularly important in patients who suffer late deterioration, which is sometimes caused by treatable etiologies, such as development or enlargement of intramedullary cavities. MRA Neck There is no role for MRA in the evaluation of suspected traumatic cervical myelopathy or radiculopathy [59].

69359

acrac_69359_9

Suspected Spine Trauma PCAs

If there is concern for arterial dissection that is due to the mechanism of injury, please refer to Variant 5. Arteriography Cervicocerebral There is no role for arteriography in the assessment of patients with suspected traumatic cervical spinal cord or nerve root injury. If there is concern for arterial dissection that is due to the mechanism of injury, please refer to Variant 5. Variant 4: Age greater than or equal to 16 years. Acute cervical spine injury detected on radiographs. Treatment planning for mechanically unstable spine. CT Myelography Cervical Spine There is no role for CT myelography in the preoperative assessment of a mechanically unstable cervical spine in the absence of cervical spinal cord injury. If spinal cord injury is present, CT myelography may be beneficial in identifying the level and extent of cervical cord compression to aid in planning for cervical decompression. However, CT myelography is inferior to MRI in assessing cord contusion, cord hemorrhage, and postganglionic nerve root injuries [40,41,43,57], making CT myelography less desirable than MRI for preoperative assessment for the unstable cervical spine with associated neurologic injury. CT Cervical Spine CT of the cervical spine is essential in the preoperative assessment of an unstable cervical spine injury. CT is the gold standard for identification of cervical spine fractures [31] and is complementary to MRI in preoperative assessment. Contrast does not provide added value. MRI Cervical Spine MRI is complementary to CT in preoperative assessment of the unstable cervical spine. Assessment of the discoligamentous complex integrity is a crucial component in preoperative assessment of the cervical spine [60,61]. Discoligamentous injury is invariably present in a mechanically unstable cervical spine, and MRI is the gold standard for assessment of soft-tissue injuries, including injury to the discoligament complex [37-42].

Suspected Spine Trauma PCAs. If there is concern for arterial dissection that is due to the mechanism of injury, please refer to Variant 5. Arteriography Cervicocerebral There is no role for arteriography in the assessment of patients with suspected traumatic cervical spinal cord or nerve root injury. If there is concern for arterial dissection that is due to the mechanism of injury, please refer to Variant 5. Variant 4: Age greater than or equal to 16 years. Acute cervical spine injury detected on radiographs. Treatment planning for mechanically unstable spine. CT Myelography Cervical Spine There is no role for CT myelography in the preoperative assessment of a mechanically unstable cervical spine in the absence of cervical spinal cord injury. If spinal cord injury is present, CT myelography may be beneficial in identifying the level and extent of cervical cord compression to aid in planning for cervical decompression. However, CT myelography is inferior to MRI in assessing cord contusion, cord hemorrhage, and postganglionic nerve root injuries [40,41,43,57], making CT myelography less desirable than MRI for preoperative assessment for the unstable cervical spine with associated neurologic injury. CT Cervical Spine CT of the cervical spine is essential in the preoperative assessment of an unstable cervical spine injury. CT is the gold standard for identification of cervical spine fractures [31] and is complementary to MRI in preoperative assessment. Contrast does not provide added value. MRI Cervical Spine MRI is complementary to CT in preoperative assessment of the unstable cervical spine. Assessment of the discoligamentous complex integrity is a crucial component in preoperative assessment of the cervical spine [60,61]. Discoligamentous injury is invariably present in a mechanically unstable cervical spine, and MRI is the gold standard for assessment of soft-tissue injuries, including injury to the discoligament complex [37-42].

69359

acrac_69359_10

Suspected Spine Trauma PCAs

MRI has the added benefit of identifying additional soft-tissue injuries frequently associated with cervical spine instability, such as epidural hematoma and cord contusion, which also may necessitate surgical management. Suspected Spine Trauma However, there are no widely accepted criteria for grading the severity of cervical spine soft-tissue injury on MRI, and while MRI has been shown to have high sensitivity for identifying soft-tissue injuries of the cervical spine, the specificity of MRI for identifying clinically significant cervical soft-tissue injuries is only modest. In a 2015 study by Zhuge et al [62], MRI demonstrated 100% sensitivity for diagnosis of injury to the cervical paraspinal muscles, intervertebral disc, and interspinous ligament but with specificities of only 77%, 71%, and 64% for these structures, respectively. Therefore, care should be taken in interpretation of soft-tissue injuries identified on MRI. Variant 5: Age greater than or equal to 16 years. Suspected acute cervical spine blunt trauma. Clinical or imaging findings suggest arterial injury with or without positive cervical spine CT. Next imaging study. Arterial injury can be a concern in blunt and penetrating spinal injury. An estimated 1% to 3% of blunt trauma patients are diagnosed with cerebrovascular transection, pseudoaneurysm formation, and simple dissection. Dissections and pseudoaneurysms may or may not produce stenosis and flow limitation of the affected artery. The presence of dissection in itself is generally taken to represent a risk of thrombus formation and subsequent embolization. Many different head and neck injury patterns and clinical symptoms have been associated with blunt cerebrovascular injuries (BCVIs) [52,53,63-68]. Up to two-thirds of patients with BCVIs may be asymptomatic at presentation [65] and not develop stroke-like symptoms for 48 to 72 hours after initial blunt trauma injury [63,64].

Suspected Spine Trauma PCAs. MRI has the added benefit of identifying additional soft-tissue injuries frequently associated with cervical spine instability, such as epidural hematoma and cord contusion, which also may necessitate surgical management. Suspected Spine Trauma However, there are no widely accepted criteria for grading the severity of cervical spine soft-tissue injury on MRI, and while MRI has been shown to have high sensitivity for identifying soft-tissue injuries of the cervical spine, the specificity of MRI for identifying clinically significant cervical soft-tissue injuries is only modest. In a 2015 study by Zhuge et al [62], MRI demonstrated 100% sensitivity for diagnosis of injury to the cervical paraspinal muscles, intervertebral disc, and interspinous ligament but with specificities of only 77%, 71%, and 64% for these structures, respectively. Therefore, care should be taken in interpretation of soft-tissue injuries identified on MRI. Variant 5: Age greater than or equal to 16 years. Suspected acute cervical spine blunt trauma. Clinical or imaging findings suggest arterial injury with or without positive cervical spine CT. Next imaging study. Arterial injury can be a concern in blunt and penetrating spinal injury. An estimated 1% to 3% of blunt trauma patients are diagnosed with cerebrovascular transection, pseudoaneurysm formation, and simple dissection. Dissections and pseudoaneurysms may or may not produce stenosis and flow limitation of the affected artery. The presence of dissection in itself is generally taken to represent a risk of thrombus formation and subsequent embolization. Many different head and neck injury patterns and clinical symptoms have been associated with blunt cerebrovascular injuries (BCVIs) [52,53,63-68]. Up to two-thirds of patients with BCVIs may be asymptomatic at presentation [65] and not develop stroke-like symptoms for 48 to 72 hours after initial blunt trauma injury [63,64].

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acrac_69359_11

Suspected Spine Trauma PCAs

Screening for BCVI is ideally performed to appropriately initiate anticoagulation therapy prior to the patient developing neurologic deficits. While there are no universally accepted criteria for guiding imaging evaluation for BCVI, the high sensitivity and excellent negative predictive value of the revised Denver criteria make it a reasonable set of criteria when screening blunt trauma patients for BCVI. The Denver screening criteria was first proposed in 1994 and subsequently revised in 2004 [63] and 2011 [65]. Under the revised Denver criteria, cerebrovascular imaging is indicated in any patient who has one of the signs or symptoms of BCVI or one of the risk factors for BCVI (Table 5). Beliaev et al [69] in 2014 validated the revised Denver criteria, finding 97% sensitivity for detecting BCVI with negative predictive value of 99.6%. Geddes et al [64] compared incidence of BCVI before and after introduction of the revised Denver protocol and found an incidence of BCVI of 2.99% in blunt trauma patients after implementation of the revised Denver protocol compared with an incidence of 2.36% prior to use of the Denver protocol, which suggests that the protocol finds a significant number of cases of BCVI compared with prior screening methods. Geddes et al [64] also noted that use of the revised Denver protocol resulted in 29% more BCVIs identified in asymptomatic blunt trauma patients compared with their prior screening criteria. Suspected Spine Trauma CTA Head and Neck In the past two decades, CTA has seen a dramatic improvement in both speed of image acquisition and resolution. This has resulted in significant improvement in the ability of CTA to detect cervical vascular injuries.

Suspected Spine Trauma PCAs. Screening for BCVI is ideally performed to appropriately initiate anticoagulation therapy prior to the patient developing neurologic deficits. While there are no universally accepted criteria for guiding imaging evaluation for BCVI, the high sensitivity and excellent negative predictive value of the revised Denver criteria make it a reasonable set of criteria when screening blunt trauma patients for BCVI. The Denver screening criteria was first proposed in 1994 and subsequently revised in 2004 [63] and 2011 [65]. Under the revised Denver criteria, cerebrovascular imaging is indicated in any patient who has one of the signs or symptoms of BCVI or one of the risk factors for BCVI (Table 5). Beliaev et al [69] in 2014 validated the revised Denver criteria, finding 97% sensitivity for detecting BCVI with negative predictive value of 99.6%. Geddes et al [64] compared incidence of BCVI before and after introduction of the revised Denver protocol and found an incidence of BCVI of 2.99% in blunt trauma patients after implementation of the revised Denver protocol compared with an incidence of 2.36% prior to use of the Denver protocol, which suggests that the protocol finds a significant number of cases of BCVI compared with prior screening methods. Geddes et al [64] also noted that use of the revised Denver protocol resulted in 29% more BCVIs identified in asymptomatic blunt trauma patients compared with their prior screening criteria. Suspected Spine Trauma CTA Head and Neck In the past two decades, CTA has seen a dramatic improvement in both speed of image acquisition and resolution. This has resulted in significant improvement in the ability of CTA to detect cervical vascular injuries.

69359

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Suspected Spine Trauma PCAs

Using conventional angiography as a gold standard, recent studies using multislice CT scanners with 16 or more detector rows have found CTA to have a reported sensitivity of 41% to 98% and specificity of 81% to 100% for identifying cervical arterial injury [50,54], although, using catheter angiography as the gold standard inherently places CTA at a disadvantage when comparing the two modalities because catheter angiography is assumed to be 100% sensitive and 100% specific. CTA has been shown to detect almost all clinically relevant blunt cervical arterial injuries, with lower complication rates than conventional arteriography [50,52,54,70]. At many institutions, CTA has replaced conventional arteriography for screening of blunt cervical arterial injury in high-risk patients because of the short acquisition time, low complication rate, and ability to perform CTA at the same time as the neck is being imaged for cervical spine injury. MRA Neck MRA of the neck is considered an equivalent imaging modality to CTA in assessment of blunt cervical vascular injury. Similar to CTA, MRA has been shown to be inferior to conventional arteriography in identifying cervical arterial injury [50,54]. However, like CTA, modern MRA does identify almost all clinically significant cervical arterial injuries [54]. Fewer data are available on the performance of MRA in identifying cervical arterial injury compared with CTA. In the only study directly comparing MRA with CTA, CTA was found to be slightly preferable to MRA for identification of blunt cervical arterial injuries [71]. However, because of its superior soft- tissue contrast, MRA may be better than CTA or conventional arteriography in identifying intramural hematoma [71]. A study by Biffl et al [51] in 2002 also found MRA to perform comparably to CTA in diagnosing BCVI, with MRA having a reported sensitivity of 75% and specificity of 67% compared to a sensitivity of 68% and specificity of 67% found in CTA.

Suspected Spine Trauma PCAs. Using conventional angiography as a gold standard, recent studies using multislice CT scanners with 16 or more detector rows have found CTA to have a reported sensitivity of 41% to 98% and specificity of 81% to 100% for identifying cervical arterial injury [50,54], although, using catheter angiography as the gold standard inherently places CTA at a disadvantage when comparing the two modalities because catheter angiography is assumed to be 100% sensitive and 100% specific. CTA has been shown to detect almost all clinically relevant blunt cervical arterial injuries, with lower complication rates than conventional arteriography [50,52,54,70]. At many institutions, CTA has replaced conventional arteriography for screening of blunt cervical arterial injury in high-risk patients because of the short acquisition time, low complication rate, and ability to perform CTA at the same time as the neck is being imaged for cervical spine injury. MRA Neck MRA of the neck is considered an equivalent imaging modality to CTA in assessment of blunt cervical vascular injury. Similar to CTA, MRA has been shown to be inferior to conventional arteriography in identifying cervical arterial injury [50,54]. However, like CTA, modern MRA does identify almost all clinically significant cervical arterial injuries [54]. Fewer data are available on the performance of MRA in identifying cervical arterial injury compared with CTA. In the only study directly comparing MRA with CTA, CTA was found to be slightly preferable to MRA for identification of blunt cervical arterial injuries [71]. However, because of its superior soft- tissue contrast, MRA may be better than CTA or conventional arteriography in identifying intramural hematoma [71]. A study by Biffl et al [51] in 2002 also found MRA to perform comparably to CTA in diagnosing BCVI, with MRA having a reported sensitivity of 75% and specificity of 67% compared to a sensitivity of 68% and specificity of 67% found in CTA.

69359

acrac_69359_13

Suspected Spine Trauma PCAs

Time-of-flight or phase-contrast sequences can be employed without the use of IV contrast for creation of virtual arteriograms. However, the use of IV contrast with 3-D time-of-flight imaging may greatly improve depiction of the vessels for identification of subtle stenosis or pseudoaneurysm formation. In addition, axial T1-weighted fat- suppressed images of the neck can greatly aid in the identification of intramural hematoma [71]. Three- dimensional magnetization-prepared rapid gradient-echo and diffusion-weighted imaging can also show mural thrombus related to dissection. Variant 6: Age greater than or equal to 16 years. Suspected acute cervical spine blunt trauma. Obtunded patient with no traumatic injury identified on cervical spine CT. Next imaging study after CT cervical spine without IV contrast. Radiography Cervical Spine There is no role for routine radiographs in assessment of an obtunded patient without traumatic injury identified on CT. Flexion-extension radiographs have been employed by some for exclusion of ligament injury. However, between 30% to 95% of dynamic flexion-extension radiographs have been found to be inadequate to exclude ligament injury because of limited motion and inadequate visualization of the lower cervical spine [35,74]. Even when flexion-extension radiographs adequately visualize the cervical spine, they rarely identify clinically significant cervical spine instability not apparent on CT, with reported positive predictive value as low as 0% [74- 76]. Flexion-extension radiographs have also been shown to identify fewer cervical ligament injuries compared with MRI. In a study of 48 patients with cervical spine trauma by Duane et al [75] in 2010 comparing flexion- extension radiographs with cervical spine MRI for diagnosing cervical spine ligament injury, none of the 8 Suspected Spine Trauma patients with ligament injury identified on MRI had an abnormality identified on flexion-extension radiographs.

Suspected Spine Trauma PCAs. Time-of-flight or phase-contrast sequences can be employed without the use of IV contrast for creation of virtual arteriograms. However, the use of IV contrast with 3-D time-of-flight imaging may greatly improve depiction of the vessels for identification of subtle stenosis or pseudoaneurysm formation. In addition, axial T1-weighted fat- suppressed images of the neck can greatly aid in the identification of intramural hematoma [71]. Three- dimensional magnetization-prepared rapid gradient-echo and diffusion-weighted imaging can also show mural thrombus related to dissection. Variant 6: Age greater than or equal to 16 years. Suspected acute cervical spine blunt trauma. Obtunded patient with no traumatic injury identified on cervical spine CT. Next imaging study after CT cervical spine without IV contrast. Radiography Cervical Spine There is no role for routine radiographs in assessment of an obtunded patient without traumatic injury identified on CT. Flexion-extension radiographs have been employed by some for exclusion of ligament injury. However, between 30% to 95% of dynamic flexion-extension radiographs have been found to be inadequate to exclude ligament injury because of limited motion and inadequate visualization of the lower cervical spine [35,74]. Even when flexion-extension radiographs adequately visualize the cervical spine, they rarely identify clinically significant cervical spine instability not apparent on CT, with reported positive predictive value as low as 0% [74- 76]. Flexion-extension radiographs have also been shown to identify fewer cervical ligament injuries compared with MRI. In a study of 48 patients with cervical spine trauma by Duane et al [75] in 2010 comparing flexion- extension radiographs with cervical spine MRI for diagnosing cervical spine ligament injury, none of the 8 Suspected Spine Trauma patients with ligament injury identified on MRI had an abnormality identified on flexion-extension radiographs.

69359

acrac_69359_14

Suspected Spine Trauma PCAs

Furthermore, flexion-extension radiographs carry the real danger of producing neurologic injury. CT Myelography Cervical Spine There is no role for myelography in assessment of an obtunded patient without traumatic injury identified on CT in the absence of physical examination signs of spinal cord or nerve root injury. CTA Head and Neck Patients presenting with a neurologic abnormality that is unexplained by a diagnosed cervical spine injury should be evaluated for blunt cerebrovascular injury [65]. While not limited to obtunded patients, recent prospective multicenter trials suggest that MRI has a role in evaluating patients who have a negative cervical spine CT. The Western Trauma Association Multi-Institutional trial reported that CT was effective for ruling out clinically significant injury with a sensitivity of 98.5%. A small but clinically significant incidence of a missed injury was noted [56]. The prospective ReCONECT trial studied 767 patients who had a negative cervical spine CT and went on to MRI because of cervicalgia (43.0%), inability to evaluate (44.1%), or both (9.4%). MRI was abnormal in 23.6% of all patients, including ligamentous injury (16.6%), soft-tissue swelling (4.3%), vertebral disc injury (1.4%), and dural hematomas (1.3%). The patients with abnormal MRI were less likely to have their cervical collar removed than those with normal MRI (13.3% versus 88.1%). Eleven patients underwent cervical spine surgery after the MRI results. The clinical significance of these abnormal MRI findings could not be determined from this study group [55]. By inference, it is likely that some obtunded patients with negative cervical spine CT will have abnormal MRI, and some of these MRI-detected injuries may require treatment. MRA Neck There is no role for MRA in assessment of obtunded patients without traumatic injury identified on CT in the absence of clinical findings concerning for cervical vascular injury.

Suspected Spine Trauma PCAs. Furthermore, flexion-extension radiographs carry the real danger of producing neurologic injury. CT Myelography Cervical Spine There is no role for myelography in assessment of an obtunded patient without traumatic injury identified on CT in the absence of physical examination signs of spinal cord or nerve root injury. CTA Head and Neck Patients presenting with a neurologic abnormality that is unexplained by a diagnosed cervical spine injury should be evaluated for blunt cerebrovascular injury [65]. While not limited to obtunded patients, recent prospective multicenter trials suggest that MRI has a role in evaluating patients who have a negative cervical spine CT. The Western Trauma Association Multi-Institutional trial reported that CT was effective for ruling out clinically significant injury with a sensitivity of 98.5%. A small but clinically significant incidence of a missed injury was noted [56]. The prospective ReCONECT trial studied 767 patients who had a negative cervical spine CT and went on to MRI because of cervicalgia (43.0%), inability to evaluate (44.1%), or both (9.4%). MRI was abnormal in 23.6% of all patients, including ligamentous injury (16.6%), soft-tissue swelling (4.3%), vertebral disc injury (1.4%), and dural hematomas (1.3%). The patients with abnormal MRI were less likely to have their cervical collar removed than those with normal MRI (13.3% versus 88.1%). Eleven patients underwent cervical spine surgery after the MRI results. The clinical significance of these abnormal MRI findings could not be determined from this study group [55]. By inference, it is likely that some obtunded patients with negative cervical spine CT will have abnormal MRI, and some of these MRI-detected injuries may require treatment. MRA Neck There is no role for MRA in assessment of obtunded patients without traumatic injury identified on CT in the absence of clinical findings concerning for cervical vascular injury.

69359

acrac_69359_15

Suspected Spine Trauma PCAs

Arteriography Cervicocerebral There is no role for arteriography in assessment of obtunded patients without traumatic injury identified on CT in the absence of clinical findings concerning for cervical vascular injury. Variant 7: Age greater than or equal to 16 years. Suspected acute cervical spine blunt trauma. Clinical or imaging findings suggest ligamentous injury. Next imaging study after CT cervical spine without IV contrast. Radiography Cervical Spine The literature has been uniformly negative in assessing the utility of static flexion-extension radiographs or dynamic fluoroscopy for detection of cervical spine ligamentous injuries [32-35,81]. Studies have reported anywhere from 28% to 97% of flexion-extension studies are inadequate for evaluating ligament injury [33-35,82]. Even when flexion-extension radiographs are technically adequate, they rarely demonstrate evidence of ligament instability [32,34,76,81], and positive studies rarely result in significant change in clinical management [32,33,76,81]. The low rate of technically adequate studies along with the low sensitivity and specificity of Suspected Spine Trauma flexion-extension radiographs makes this study undesirable for assessment of cervical spine ligament injuries. Furthermore, flexion-extension radiographs carry the real danger of producing neurologic injury. Flexion- extension radiographs fail to reveal most ligament injuries identified on MRI and can result in increased length of cervical immobilization [74,75]. In the very limited circumstance where MRI findings are equivocal for ligamentous injury, flexion-extension radiographs may be useful to determine whether the MRI findings correlate with pathologic motion. MRI has a high sensitivity for cervical ligament injury and identifies many ligament injuries that are clinically insignificant [42,62]. Flexion-extension radiographs are most appropriate when MRI has demonstrated abnormal signal in spinal ligaments without definite disruption.

Suspected Spine Trauma PCAs. Arteriography Cervicocerebral There is no role for arteriography in assessment of obtunded patients without traumatic injury identified on CT in the absence of clinical findings concerning for cervical vascular injury. Variant 7: Age greater than or equal to 16 years. Suspected acute cervical spine blunt trauma. Clinical or imaging findings suggest ligamentous injury. Next imaging study after CT cervical spine without IV contrast. Radiography Cervical Spine The literature has been uniformly negative in assessing the utility of static flexion-extension radiographs or dynamic fluoroscopy for detection of cervical spine ligamentous injuries [32-35,81]. Studies have reported anywhere from 28% to 97% of flexion-extension studies are inadequate for evaluating ligament injury [33-35,82]. Even when flexion-extension radiographs are technically adequate, they rarely demonstrate evidence of ligament instability [32,34,76,81], and positive studies rarely result in significant change in clinical management [32,33,76,81]. The low rate of technically adequate studies along with the low sensitivity and specificity of Suspected Spine Trauma flexion-extension radiographs makes this study undesirable for assessment of cervical spine ligament injuries. Furthermore, flexion-extension radiographs carry the real danger of producing neurologic injury. Flexion- extension radiographs fail to reveal most ligament injuries identified on MRI and can result in increased length of cervical immobilization [74,75]. In the very limited circumstance where MRI findings are equivocal for ligamentous injury, flexion-extension radiographs may be useful to determine whether the MRI findings correlate with pathologic motion. MRI has a high sensitivity for cervical ligament injury and identifies many ligament injuries that are clinically insignificant [42,62]. Flexion-extension radiographs are most appropriate when MRI has demonstrated abnormal signal in spinal ligaments without definite disruption.

69359

acrac_69359_16

Suspected Spine Trauma PCAs

In this situation, where the level and nature of a suspected lesion are known, flexion-extension radiographs may aid in assessing the significance of the MRI findings. However, care should be taken to ensure adequate flexion and extension of cervical radiographs as muscle spasm can limit cervical mobility, masking mechanically unstable cervical injuries. CT Myelography Cervical Spine There is no role for CT myelography in assessment of suspected cervical ligament injury in the absence of clinical suspicion for vascular injury. CTA Head and Neck There is no role for CTA in assessment of patients with suspected cervical ligament injury in the absence of clinical suspicion for vascular injury. MRI is superior to CT in identifying cervical spine ligament injuries. However, ligament injuries that are occult on CT and identified on MRI rarely result in significant changes in clinical management. Studies looking at presence of soft-tissue injury on cervical spine MRI in patients with unreliable examination and negative CT have found MRI to be positive in 6% to 49% of patients [41,44,45,47,48,78]. Most of these injuries were minor, requiring either no change in management or only extended cervical collar placement. Less than 1% of patients with unreliable clinical examination and negative cervical spine CT will have an unstable cervical spine injury requiring surgical stabilization identified on MRI [38-41,44-48,78-80]. MRA Neck There is no role for MRA in assessment of patients with suspected cervical ligament injury in the absence of clinical suspicion for vascular injury. Arteriography Cervicocerebral There is no role for arteriography in assessment of patients with suspected cervical ligament injury in the absence of clinical suspicion for vascular injury. Variant 8: Age greater than or equal to 16 years. Suspected acute cervical spine blunt trauma. Follow-up imaging on patient with no unstable injury demonstrated initially, but kept in collar for neck pain. No new neurologic symptoms.

Suspected Spine Trauma PCAs. In this situation, where the level and nature of a suspected lesion are known, flexion-extension radiographs may aid in assessing the significance of the MRI findings. However, care should be taken to ensure adequate flexion and extension of cervical radiographs as muscle spasm can limit cervical mobility, masking mechanically unstable cervical injuries. CT Myelography Cervical Spine There is no role for CT myelography in assessment of suspected cervical ligament injury in the absence of clinical suspicion for vascular injury. CTA Head and Neck There is no role for CTA in assessment of patients with suspected cervical ligament injury in the absence of clinical suspicion for vascular injury. MRI is superior to CT in identifying cervical spine ligament injuries. However, ligament injuries that are occult on CT and identified on MRI rarely result in significant changes in clinical management. Studies looking at presence of soft-tissue injury on cervical spine MRI in patients with unreliable examination and negative CT have found MRI to be positive in 6% to 49% of patients [41,44,45,47,48,78]. Most of these injuries were minor, requiring either no change in management or only extended cervical collar placement. Less than 1% of patients with unreliable clinical examination and negative cervical spine CT will have an unstable cervical spine injury requiring surgical stabilization identified on MRI [38-41,44-48,78-80]. MRA Neck There is no role for MRA in assessment of patients with suspected cervical ligament injury in the absence of clinical suspicion for vascular injury. Arteriography Cervicocerebral There is no role for arteriography in assessment of patients with suspected cervical ligament injury in the absence of clinical suspicion for vascular injury. Variant 8: Age greater than or equal to 16 years. Suspected acute cervical spine blunt trauma. Follow-up imaging on patient with no unstable injury demonstrated initially, but kept in collar for neck pain. No new neurologic symptoms.

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acrac_69359_17

Suspected Spine Trauma PCAs

Includes whiplash associated disorders. It is not uncommon for patients to report persistent neck symptoms after sustaining blunt cervical trauma, even in light of negative initial cervical spine imaging. Neck pain and stiffness, mechanical symptoms (ie, decreased range of motion, point tenderness), and neurologic symptoms frequently persist for months after sustaining cervical trauma and constitute a spectrum of cervical spine injuries commonly referred to as whiplash associated disorders (WAD) [84]. Many different structures have been hypothesized as the source of pain in WAD, most notably the paraspinal muscles, facets, discs, and craniocervical ligaments [85-91]. However, the exact etiology of WAD is unknown, with multiple soft-tissue structures likely contributing to WAD symptoms. Suspected Spine Trauma Imaging has been found to be of little usefulness in diagnosing and predicting prognosis of WAD [85,86,88,89,92-97]. As such, the diagnosis and prognosis assessment of WAD is based almost exclusively on clinical and psychosocial data. Imaging can be of clinical utility in this population by excluding delayed presentation of cervical spine instability missed during the initial cervical spine evaluation and allowing patients to begin exercise and mobilization of the cervical spine, which has been shown to be effective in reducing symptoms of acute and chronic WAD [98,99]. CT Myelography Cervical Spine There is no role for CT myelography in the assessment of patients with persistent pain on follow-up visit with cervical collar in place. CT Cervical Spine There is no role for CT in the assessment of patients with persistent pain on follow-up visit with cervical collar in place. CTA Head and Neck There is no role for CTA in the assessment of patients with persistent pain on follow-up visit with cervical collar in place. MRI Cervical Spine MRI is the gold standard for imaging diagnosis of traumatic soft-tissue injuries of the neck.

Suspected Spine Trauma PCAs. Includes whiplash associated disorders. It is not uncommon for patients to report persistent neck symptoms after sustaining blunt cervical trauma, even in light of negative initial cervical spine imaging. Neck pain and stiffness, mechanical symptoms (ie, decreased range of motion, point tenderness), and neurologic symptoms frequently persist for months after sustaining cervical trauma and constitute a spectrum of cervical spine injuries commonly referred to as whiplash associated disorders (WAD) [84]. Many different structures have been hypothesized as the source of pain in WAD, most notably the paraspinal muscles, facets, discs, and craniocervical ligaments [85-91]. However, the exact etiology of WAD is unknown, with multiple soft-tissue structures likely contributing to WAD symptoms. Suspected Spine Trauma Imaging has been found to be of little usefulness in diagnosing and predicting prognosis of WAD [85,86,88,89,92-97]. As such, the diagnosis and prognosis assessment of WAD is based almost exclusively on clinical and psychosocial data. Imaging can be of clinical utility in this population by excluding delayed presentation of cervical spine instability missed during the initial cervical spine evaluation and allowing patients to begin exercise and mobilization of the cervical spine, which has been shown to be effective in reducing symptoms of acute and chronic WAD [98,99]. CT Myelography Cervical Spine There is no role for CT myelography in the assessment of patients with persistent pain on follow-up visit with cervical collar in place. CT Cervical Spine There is no role for CT in the assessment of patients with persistent pain on follow-up visit with cervical collar in place. CTA Head and Neck There is no role for CTA in the assessment of patients with persistent pain on follow-up visit with cervical collar in place. MRI Cervical Spine MRI is the gold standard for imaging diagnosis of traumatic soft-tissue injuries of the neck.

69359

acrac_69359_18

Suspected Spine Trauma PCAs

In the setting of persistent neck pain after cervical trauma, MRI may be useful for identifying ligament sprains, muscle strains, disc herniation, and bone bruising, which are the most likely causes of persistent pain. However, MRI has a tendency to overestimate the severity of ligament and other soft-tissue injuries with specificity rates reported as low as 64% to 77% for soft-tissue injury and a reported false-positive rate of 25% to 40% [42,62]. Soft-tissue edema and signal changes are often slow to resolve, persisting well after the patient has become asymptomatic. Conversely, subacute to chronic soft-tissue injuries can be difficult to appreciate once soft-tissue edema has subsided, and it is often challenging to determine integrity of scarred ligaments. For these reasons, flexion- extension radiographs may be complementary to MRI, and performed flexion-extension radiographs may better determine cervical instability in the setting of subacute or chronic cervical spine injury. Much research has been performed in an attempt to identify MRI findings that can be used to diagnose or help provide a prognosis for WAD [85,86,88,89,91-97,102,103]. These studies have primarily focused on signal changes within the craniocervical (alar and transverse) ligaments, atrophy of the paraspinal muscles, and progression of cervical degenerative changes as indicators of WAD. Associations between MRI findings and WAD are weak at best [86,87], and most studies have found no difference in MRI findings between WAD patients and non-WAD patients [85,92,94-97,103] and no correlation between MRI findings and WAD symptoms or progression [88,89]. MRA Neck There is no role for MRA in the assessment of patients with persistent pain on follow-up visit with cervical collar in place. Suspected Spine Trauma Arteriography Cervicocerebral There is no role for arteriography in the assessment of patients with persistent pain on follow-up visit with cervical collar in place.

Suspected Spine Trauma PCAs. In the setting of persistent neck pain after cervical trauma, MRI may be useful for identifying ligament sprains, muscle strains, disc herniation, and bone bruising, which are the most likely causes of persistent pain. However, MRI has a tendency to overestimate the severity of ligament and other soft-tissue injuries with specificity rates reported as low as 64% to 77% for soft-tissue injury and a reported false-positive rate of 25% to 40% [42,62]. Soft-tissue edema and signal changes are often slow to resolve, persisting well after the patient has become asymptomatic. Conversely, subacute to chronic soft-tissue injuries can be difficult to appreciate once soft-tissue edema has subsided, and it is often challenging to determine integrity of scarred ligaments. For these reasons, flexion- extension radiographs may be complementary to MRI, and performed flexion-extension radiographs may better determine cervical instability in the setting of subacute or chronic cervical spine injury. Much research has been performed in an attempt to identify MRI findings that can be used to diagnose or help provide a prognosis for WAD [85,86,88,89,91-97,102,103]. These studies have primarily focused on signal changes within the craniocervical (alar and transverse) ligaments, atrophy of the paraspinal muscles, and progression of cervical degenerative changes as indicators of WAD. Associations between MRI findings and WAD are weak at best [86,87], and most studies have found no difference in MRI findings between WAD patients and non-WAD patients [85,92,94-97,103] and no correlation between MRI findings and WAD symptoms or progression [88,89]. MRA Neck There is no role for MRA in the assessment of patients with persistent pain on follow-up visit with cervical collar in place. Suspected Spine Trauma Arteriography Cervicocerebral There is no role for arteriography in the assessment of patients with persistent pain on follow-up visit with cervical collar in place.

69359

acrac_69359_19

Suspected Spine Trauma PCAs

Variant 9: Age greater than or equal to 16 years. Blunt trauma meeting criteria for thoracic and lumbar imaging. Initial imaging. Imaging is a crucial component in assessment of thoracic and lumbar spine injury. From 1998 to 2011, there was an adjusted annual increase of approximately 8% in thoracolumbar spine fractures in patients involved in motor vehicle collisions [15]. Thoracolumbar fractures are challenging to identify clinically, with only 48% to 75% of thoracolumbar injuries identified on clinical examination [16-18]. Unlike cervical injuries, well-defined clinical criteria have not been established to determine when thoracolumbar imaging is appropriate in the setting of blunt traumatic injury. Since clinical examination has poor sensitivity for identifying thoracolumbar injuries, any high- risk patient (mid line thoracolumbar tenderness, high-energy mechanism of injury, or >60 years of age), as well as unexaminable patients (intoxicated, GCS <15, distracting injury), should undergo imaging of the thoracolumbar spine. Screening of the entire spine is advised, as an estimated 20% of spine injuries will have a second associated spinal injury at a noncontiguous level [26,27]. CT Myelography Thoracic and Lumbar Spine There is no role for CT myelography in the initial assessment of thoracolumbar spine injury. MRI Thoracic and Lumbar Spine Isolated unstable ligamentous injury in the absence of fractures appears to be extremely rare in the thoracolumbar spine, if it occurs at all. For this reason, screening the thoracolumbar spine with MRI to detect ligamentous disruption is not indicated when the CT scan is normal. As is the case for the cervical spine, symptoms or signs of spinal cord, conus medullaris, or nerve root injury indicate the need for imaging the symptomatic levels of the spine and spinal cord with MRI. Suspected Spine Trauma Variant 10: Age greater than or equal to 16 years. Acute thoracic or lumbar spine injury detected on radiographs or noncontrast CT.

Suspected Spine Trauma PCAs. Variant 9: Age greater than or equal to 16 years. Blunt trauma meeting criteria for thoracic and lumbar imaging. Initial imaging. Imaging is a crucial component in assessment of thoracic and lumbar spine injury. From 1998 to 2011, there was an adjusted annual increase of approximately 8% in thoracolumbar spine fractures in patients involved in motor vehicle collisions [15]. Thoracolumbar fractures are challenging to identify clinically, with only 48% to 75% of thoracolumbar injuries identified on clinical examination [16-18]. Unlike cervical injuries, well-defined clinical criteria have not been established to determine when thoracolumbar imaging is appropriate in the setting of blunt traumatic injury. Since clinical examination has poor sensitivity for identifying thoracolumbar injuries, any high- risk patient (mid line thoracolumbar tenderness, high-energy mechanism of injury, or >60 years of age), as well as unexaminable patients (intoxicated, GCS <15, distracting injury), should undergo imaging of the thoracolumbar spine. Screening of the entire spine is advised, as an estimated 20% of spine injuries will have a second associated spinal injury at a noncontiguous level [26,27]. CT Myelography Thoracic and Lumbar Spine There is no role for CT myelography in the initial assessment of thoracolumbar spine injury. MRI Thoracic and Lumbar Spine Isolated unstable ligamentous injury in the absence of fractures appears to be extremely rare in the thoracolumbar spine, if it occurs at all. For this reason, screening the thoracolumbar spine with MRI to detect ligamentous disruption is not indicated when the CT scan is normal. As is the case for the cervical spine, symptoms or signs of spinal cord, conus medullaris, or nerve root injury indicate the need for imaging the symptomatic levels of the spine and spinal cord with MRI. Suspected Spine Trauma Variant 10: Age greater than or equal to 16 years. Acute thoracic or lumbar spine injury detected on radiographs or noncontrast CT.

69359

acrac_69359_20

Suspected Spine Trauma PCAs

Neurologic abnormalities. Next imaging study. CT Myelography Thoracic and Lumbar Spine CT myelography can be performed to assess for traumatic spinal canal narrowing that is due to disc herniation or epidural hematoma and to assess for preganglionic nerve root avulsions. However, as with conventional CT, CT myelography is inferior to MRI in assessing cord contusion, cord hemorrhage, and postganglionic nerve root injuries [40,41,43,57]. Performance of thoracolumbar CT myelogram can also be technically challenging, particularly in patients with suspected unstable thoracolumbar spine injury. CT Thoracic and Lumbar Spine CT does play a role in the initial assessment of thoracic and lumbar spine injury. However, CT is significantly inferior to MRI in identifying many soft-tissue pathologies, such as cord contusion, epidural hematoma, and nerve root avulsions that can cause neurologic deficits requiring surgical intervention [40,41,43,57]. Therefore, CT should not be considered adequate for excluding significant soft-tissue pathology in patients presenting with thoracolumbar spine trauma and neurologic deficit. MRI Thoracic and Lumbar Spine MRI should be performed in patients who have possible spinal cord injury, in whom there is clinical concern for cord compression that is due to disc protrusion or hematoma, and in those suspected of ligamentous instability. Although numerous research studies have reported a potential value of diffusion MRI for characterizing spinal cord injury [111], technical problems have prevented widespread application of this technique to human studies. The current utility of diffusion MRI for assessing cord trauma remains unknown. Supporting Documents The evidence table, literature search, and appendix for this topic are available at https://acsearch. acr.org/list. The appendix includes the strength of evidence assessment and the final rating round tabulations for each recommendation.

Suspected Spine Trauma PCAs. Neurologic abnormalities. Next imaging study. CT Myelography Thoracic and Lumbar Spine CT myelography can be performed to assess for traumatic spinal canal narrowing that is due to disc herniation or epidural hematoma and to assess for preganglionic nerve root avulsions. However, as with conventional CT, CT myelography is inferior to MRI in assessing cord contusion, cord hemorrhage, and postganglionic nerve root injuries [40,41,43,57]. Performance of thoracolumbar CT myelogram can also be technically challenging, particularly in patients with suspected unstable thoracolumbar spine injury. CT Thoracic and Lumbar Spine CT does play a role in the initial assessment of thoracic and lumbar spine injury. However, CT is significantly inferior to MRI in identifying many soft-tissue pathologies, such as cord contusion, epidural hematoma, and nerve root avulsions that can cause neurologic deficits requiring surgical intervention [40,41,43,57]. Therefore, CT should not be considered adequate for excluding significant soft-tissue pathology in patients presenting with thoracolumbar spine trauma and neurologic deficit. MRI Thoracic and Lumbar Spine MRI should be performed in patients who have possible spinal cord injury, in whom there is clinical concern for cord compression that is due to disc protrusion or hematoma, and in those suspected of ligamentous instability. Although numerous research studies have reported a potential value of diffusion MRI for characterizing spinal cord injury [111], technical problems have prevented widespread application of this technique to human studies. The current utility of diffusion MRI for assessing cord trauma remains unknown. Supporting Documents The evidence table, literature search, and appendix for this topic are available at https://acsearch. acr.org/list. The appendix includes the strength of evidence assessment and the final rating round tabulations for each recommendation.

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Chest Pain Possible Acute Coronary Syndrome PCAs

Introduction/Background Cardiovascular disease is the leading cause of death in the United States. Annually, there are more than 8 million visits to emergency departments by patients with acute chest pain [1], with estimated health care costs of $13 to $15 billion [2]. Approximately 5% to 13% of those patients who present with acute chest pain are eventually found to have an acute coronary syndrome (ACS) [1]. ACS includes ST-segment elevation myocardial infarction (MI), non-ST-segment elevation (NSTE) MI, and unstable angina (acute ischemia without necrosis) [3]. Once diagnosed with ACS, the patient may be urgently transferred to a cardiac catheterization laboratory for invasive angiography and potential coronary revascularization [4,5]. For patients not identified immediately with ACS, categorizing low, intermediate, and high probability for ACS helps identify increasing risk for downstream major adverse cardiac events (MACE). Patients are predominantly stratified by clinical suspicion (including risk scores and risk stratification models), the evaluation of prompt electrocardiogram (ECG; serially if necessary), and the use of cardiac biomarkers (eg, serial troponins and B-type natriuretic peptide) [6,7]. Commonly used risk scores include the Thrombolysis in Myocardial Infarction risk score (TIMI RS), Global Registry of Acute Cardiac Events risk score (GRACE RS), the History, Electrocardiogram, Age, Risk factors, Troponin (HEART) score [8], and the Platelet glycoprotein IIb/IIIa in Unstable angina: Receptor Suppression Using Integrilin Therapy risk score (PURSUIT RS), among many others [9,10]. Risk stratification of patients into low, intermediate, and high probability for ACS may therefore differ according to available institutional resources and practice, but these categories generally correspond to increasing likelihood of downstream MACE due to ACS.

Chest Pain Possible Acute Coronary Syndrome PCAs. Introduction/Background Cardiovascular disease is the leading cause of death in the United States. Annually, there are more than 8 million visits to emergency departments by patients with acute chest pain [1], with estimated health care costs of $13 to $15 billion [2]. Approximately 5% to 13% of those patients who present with acute chest pain are eventually found to have an acute coronary syndrome (ACS) [1]. ACS includes ST-segment elevation myocardial infarction (MI), non-ST-segment elevation (NSTE) MI, and unstable angina (acute ischemia without necrosis) [3]. Once diagnosed with ACS, the patient may be urgently transferred to a cardiac catheterization laboratory for invasive angiography and potential coronary revascularization [4,5]. For patients not identified immediately with ACS, categorizing low, intermediate, and high probability for ACS helps identify increasing risk for downstream major adverse cardiac events (MACE). Patients are predominantly stratified by clinical suspicion (including risk scores and risk stratification models), the evaluation of prompt electrocardiogram (ECG; serially if necessary), and the use of cardiac biomarkers (eg, serial troponins and B-type natriuretic peptide) [6,7]. Commonly used risk scores include the Thrombolysis in Myocardial Infarction risk score (TIMI RS), Global Registry of Acute Cardiac Events risk score (GRACE RS), the History, Electrocardiogram, Age, Risk factors, Troponin (HEART) score [8], and the Platelet glycoprotein IIb/IIIa in Unstable angina: Receptor Suppression Using Integrilin Therapy risk score (PURSUIT RS), among many others [9,10]. Risk stratification of patients into low, intermediate, and high probability for ACS may therefore differ according to available institutional resources and practice, but these categories generally correspond to increasing likelihood of downstream MACE due to ACS.

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Chest Pain Possible Acute Coronary Syndrome PCAs

Historical risk scores such as the TIMI score, the GRACE score, and the PURSUIT score are being replaced by more accurate risk stratification tools such as the HEART score, which was designed specifically for evaluation of patients with chest pain in the emergency department without a diagnosis of ACS [8]. Noninvasive imaging may therefore be indicated for risk stratification and clinical management in both low-risk and intermediate-risk patients [17]. This has continued to gain popularity since the first decade of the 2000s, with 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] Chest Pain-Possible Acute Coronary Syndrome advanced medical imaging among chest pain patients quintupling [18]. This approach also serves to identify patients with a significant ischemic burden who could benefit from coronary revascularization [19-21]. Noninvasive imaging aids in the evaluation of the acute chest pain patients by either functionally determining a myocardial segment perfusion abnormality (eg, relative hypoperfusion, or a wall motion, or thickening abnormality, usually at stress testing) or anatomically visualizing an obstructive coronary artery stenosis. Although noninvasive imaging approaches have sensitivities and specificities in the 85% to 90% range, the corresponding false diagnosis rates are in the 10% to 15% range, and therefore consideration may be made to avoid diagnostic imaging altogether in patients at either end of the pretest probability spectrum [22].

Chest Pain Possible Acute Coronary Syndrome PCAs. Historical risk scores such as the TIMI score, the GRACE score, and the PURSUIT score are being replaced by more accurate risk stratification tools such as the HEART score, which was designed specifically for evaluation of patients with chest pain in the emergency department without a diagnosis of ACS [8]. Noninvasive imaging may therefore be indicated for risk stratification and clinical management in both low-risk and intermediate-risk patients [17]. This has continued to gain popularity since the first decade of the 2000s, with 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] Chest Pain-Possible Acute Coronary Syndrome advanced medical imaging among chest pain patients quintupling [18]. This approach also serves to identify patients with a significant ischemic burden who could benefit from coronary revascularization [19-21]. Noninvasive imaging aids in the evaluation of the acute chest pain patients by either functionally determining a myocardial segment perfusion abnormality (eg, relative hypoperfusion, or a wall motion, or thickening abnormality, usually at stress testing) or anatomically visualizing an obstructive coronary artery stenosis. Although noninvasive imaging approaches have sensitivities and specificities in the 85% to 90% range, the corresponding false diagnosis rates are in the 10% to 15% range, and therefore consideration may be made to avoid diagnostic imaging altogether in patients at either end of the pretest probability spectrum [22].

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Chest Pain Possible Acute Coronary Syndrome PCAs

Therefore, patient selection, as determined by clinical judgment and tools such as the HEART score, is critical because there has been historically a low yield of routine noninvasive cardiac imaging in low-risk patients [23-26]. The available noninvasive cardiac imaging modalities include chest radiographs, rest single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI), stress SPECT MPI, echocardiography (transthoracic and transesophageal), multidetector CT, PET (metabolic and perfusion), and MRI. All procedure elements are essential: 1) timing, 2) recons/reformats, and 3) 3-D renderings. 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 CPT codes. Discussion of Procedures by Variant Variant 1: Chest pain, low to intermediate probability for acute coronary syndrome. Initial imaging. Arteriography Coronary In patients with low to intermediate risk, arteriography is not the first-line evaluation or management. Patients with a nondiagnostic ECG and negative cardiac biomarkers should follow a clinical pathway beginning with a noninvasive approach [30]. Radiography Chest Chest radiography is primarily used for ruling out conditions that may masquerade as acute myocardial ischemia, as well as defining secondary findings that may accompany acute MI. Acute pulmonary edema can be seen on chest radiographs without enlargement of the cardiac silhouette in patients with acute MI and no prior history of ischemic damage or associated mitral valve disease. Although chest radiography is insufficient to confirm or exclude the presence of significant CAD, it may be useful in demonstrating clinically important pathology in a significant minority of ACS-suspected patients [31].

Chest Pain Possible Acute Coronary Syndrome PCAs. Therefore, patient selection, as determined by clinical judgment and tools such as the HEART score, is critical because there has been historically a low yield of routine noninvasive cardiac imaging in low-risk patients [23-26]. The available noninvasive cardiac imaging modalities include chest radiographs, rest single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI), stress SPECT MPI, echocardiography (transthoracic and transesophageal), multidetector CT, PET (metabolic and perfusion), and MRI. All procedure elements are essential: 1) timing, 2) recons/reformats, and 3) 3-D renderings. 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 CPT codes. Discussion of Procedures by Variant Variant 1: Chest pain, low to intermediate probability for acute coronary syndrome. Initial imaging. Arteriography Coronary In patients with low to intermediate risk, arteriography is not the first-line evaluation or management. Patients with a nondiagnostic ECG and negative cardiac biomarkers should follow a clinical pathway beginning with a noninvasive approach [30]. Radiography Chest Chest radiography is primarily used for ruling out conditions that may masquerade as acute myocardial ischemia, as well as defining secondary findings that may accompany acute MI. Acute pulmonary edema can be seen on chest radiographs without enlargement of the cardiac silhouette in patients with acute MI and no prior history of ischemic damage or associated mitral valve disease. Although chest radiography is insufficient to confirm or exclude the presence of significant CAD, it may be useful in demonstrating clinically important pathology in a significant minority of ACS-suspected patients [31].

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Chest Pain Possible Acute Coronary Syndrome PCAs

Other cardiovascular entities, such as aortic aneurysms, aortic dissections, and pulmonary embolism, may be suggested from the chest radiograph but with far lower sensitivity than in other imaging modalities, such as multidetector CT. Noncardiac findings associated with chest pain that can be identified on chest radiography include pneumothorax, fractured ribs, pleural effusions, and pneumonia, among others. Chest Pain-Possible Acute Coronary Syndrome Association class I, level A recommendation for evaluation of suspected ACS [34] and has a well-established, well- supported track record in evaluating acute chest pain patients [35,36]. US Echocardiography Transthoracic Stress Stress echocardiography has been shown to be a modality equivalent to stress SPECT MPI in the acute setting in low- to intermediate-risk patients, with either exercise or a stress pharmacologic agent (such as dobutamine) inducing focal wall-motion abnormalities in the region(s) of ischemia [40-42]. When compared with stress ECG, stress echocardiography of acute chest pain patients in the emergency department has been shown to lead to fewer late events, including rehospitalization and late percutaneous coronary intervention [43,44], as well as excellent accuracy in predicting obstructive CAD on coronary angiography or subsequent cardiovascular events [45]. Positive stress echocardiography has been shown to identify incrementally more patients requiring revascularization in patients suspected of ACS when compared with a standard of care without use of imaging [46,47]. US Echocardiography Transthoracic Resting US Echocardiography Transthoracic Resting Conventional resting echocardiography in the emergency department has some limited benefit for detection of ischemic myocardium with abnormal wall motion and thereby risk stratification of suspected ACS patients [48,49]; however, it is more widely used for the evaluation of heart failure, valvular dysfunction, and pericardial effusion [41].

Chest Pain Possible Acute Coronary Syndrome PCAs. Other cardiovascular entities, such as aortic aneurysms, aortic dissections, and pulmonary embolism, may be suggested from the chest radiograph but with far lower sensitivity than in other imaging modalities, such as multidetector CT. Noncardiac findings associated with chest pain that can be identified on chest radiography include pneumothorax, fractured ribs, pleural effusions, and pneumonia, among others. Chest Pain-Possible Acute Coronary Syndrome Association class I, level A recommendation for evaluation of suspected ACS [34] and has a well-established, well- supported track record in evaluating acute chest pain patients [35,36]. US Echocardiography Transthoracic Stress Stress echocardiography has been shown to be a modality equivalent to stress SPECT MPI in the acute setting in low- to intermediate-risk patients, with either exercise or a stress pharmacologic agent (such as dobutamine) inducing focal wall-motion abnormalities in the region(s) of ischemia [40-42]. When compared with stress ECG, stress echocardiography of acute chest pain patients in the emergency department has been shown to lead to fewer late events, including rehospitalization and late percutaneous coronary intervention [43,44], as well as excellent accuracy in predicting obstructive CAD on coronary angiography or subsequent cardiovascular events [45]. Positive stress echocardiography has been shown to identify incrementally more patients requiring revascularization in patients suspected of ACS when compared with a standard of care without use of imaging [46,47]. US Echocardiography Transthoracic Resting US Echocardiography Transthoracic Resting Conventional resting echocardiography in the emergency department has some limited benefit for detection of ischemic myocardium with abnormal wall motion and thereby risk stratification of suspected ACS patients [48,49]; however, it is more widely used for the evaluation of heart failure, valvular dysfunction, and pericardial effusion [41].

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Chest Pain Possible Acute Coronary Syndrome PCAs

Advances in contrast echocardiography to evaluate ischemic changes in wall thickening [50-53] and strain echocardiography to evaluate abnormal myocardial deformation [54-57] may provide an expanded role for resting echocardiography in the evaluation of ACS, particularly in patients with active chest pain at the time of imaging. US Echocardiography Transesophageal US Echocardiography Transesophageal The primary usefulness of resting transesophageal echocardiography (TEE) in the setting of acute chest pain is in ruling out aortic dissection in unstable patients. TEE is also used to further define valvular dysfunction or intracardiac thrombus, which can be sequelae of ischemic events in the subacute setting. Because of the semi- invasive nature of TEE and because there is limited information that can be added in the setting of acute chest pain, this modality is generally not indicated in the workup of patients with acute chest pain [58]. CTA Coronary Arteries In stable patients with suggested ACS at low or intermediate risk of adverse events, a noninvasive coronary imaging test (ie, coronary CTA [CCTA]) is a proven alternative to stress testing or selective coronary angiography [19,59,60]. CCTA has a very high negative predictive value for the detection of coronary atherosclerosis with or without significant stenosis and is an alternative to stress imaging in the emergency department and inpatient settings in patients at low to intermediate risk for CAD [59,61-64]. Large randomized controlled trials (eg, CT- STAT, ROMICAT I and II, ACRIN-PA, PROSPECT, CT-COMPARE, CATCH, and CATCH-2) have amply established the high negative predictive value (eg, safe discharge) and good prognosis of a negative CCTA in low- to intermediate-risk patients suspected of ACS when compared with standard pathways that predominantly involve stress nuclear MPI [65-72].

Chest Pain Possible Acute Coronary Syndrome PCAs. Advances in contrast echocardiography to evaluate ischemic changes in wall thickening [50-53] and strain echocardiography to evaluate abnormal myocardial deformation [54-57] may provide an expanded role for resting echocardiography in the evaluation of ACS, particularly in patients with active chest pain at the time of imaging. US Echocardiography Transesophageal US Echocardiography Transesophageal The primary usefulness of resting transesophageal echocardiography (TEE) in the setting of acute chest pain is in ruling out aortic dissection in unstable patients. TEE is also used to further define valvular dysfunction or intracardiac thrombus, which can be sequelae of ischemic events in the subacute setting. Because of the semi- invasive nature of TEE and because there is limited information that can be added in the setting of acute chest pain, this modality is generally not indicated in the workup of patients with acute chest pain [58]. CTA Coronary Arteries In stable patients with suggested ACS at low or intermediate risk of adverse events, a noninvasive coronary imaging test (ie, coronary CTA [CCTA]) is a proven alternative to stress testing or selective coronary angiography [19,59,60]. CCTA has a very high negative predictive value for the detection of coronary atherosclerosis with or without significant stenosis and is an alternative to stress imaging in the emergency department and inpatient settings in patients at low to intermediate risk for CAD [59,61-64]. Large randomized controlled trials (eg, CT- STAT, ROMICAT I and II, ACRIN-PA, PROSPECT, CT-COMPARE, CATCH, and CATCH-2) have amply established the high negative predictive value (eg, safe discharge) and good prognosis of a negative CCTA in low- to intermediate-risk patients suspected of ACS when compared with standard pathways that predominantly involve stress nuclear MPI [65-72].

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Chest Pain Possible Acute Coronary Syndrome PCAs

Normal CCTA has been shown to allow safe discharge from the emergency department without further workup, in both academic and community settings, with a negative predictive value for ACS over 95% [1,73-75], with equal or superior diagnostic performance when compared with stress echocardiography or nuclear MPI [76]. High-sensitivity troponin use has increased in Europe and in the United States to stratify patients with suspected ACS [77], but a CCTA strategy has still been found to be useful to avoid unnecessary downstream testing even when patients were first stratified by high-sensitivity troponin [78-80]. In a large multicenter study Chest Pain-Possible Acute Coronary Syndrome comparing CCTA with multiple other modalities used for ACS (stress cardiac MR [CMR], stress echocardiography, stress nuclear MPI, and stress PET), CCTA was found to have the highest diagnostic accuracy in finding patients with a significant coronary artery stenosis [81]. CT Coronary Calcium CT Coronary Calcium The role of the calcium score as a standalone test in the acute setting has not been established [94]. Limited studies have been performed demonstrating that the absence of coronary artery calcium (CAC) has a high negative predictive value for ACS among lower-risk patients with chest pain [95]. Several studies have suggested that in young patients with chest pain, a calcium score of zero is not a reliable test to exclude CAD, and adverse events have been shown to occur in up to 6% of acute chest pain patients without coronary artery calcium [96]. The ability of a zero calcium score to allow safe discharge of low-risk acute chest pain patients continues to be actively studied [97-100]. CT Chest CT Chest Nongated chest CT, although useful for evaluating noncardiac thoracic pathology, does not currently have a role in the evaluation of possible ACS, although perfusion defects can be seen on contrast-enhanced nongated chest CT in patients with ACS [101,102].

Chest Pain Possible Acute Coronary Syndrome PCAs. Normal CCTA has been shown to allow safe discharge from the emergency department without further workup, in both academic and community settings, with a negative predictive value for ACS over 95% [1,73-75], with equal or superior diagnostic performance when compared with stress echocardiography or nuclear MPI [76]. High-sensitivity troponin use has increased in Europe and in the United States to stratify patients with suspected ACS [77], but a CCTA strategy has still been found to be useful to avoid unnecessary downstream testing even when patients were first stratified by high-sensitivity troponin [78-80]. In a large multicenter study Chest Pain-Possible Acute Coronary Syndrome comparing CCTA with multiple other modalities used for ACS (stress cardiac MR [CMR], stress echocardiography, stress nuclear MPI, and stress PET), CCTA was found to have the highest diagnostic accuracy in finding patients with a significant coronary artery stenosis [81]. CT Coronary Calcium CT Coronary Calcium The role of the calcium score as a standalone test in the acute setting has not been established [94]. Limited studies have been performed demonstrating that the absence of coronary artery calcium (CAC) has a high negative predictive value for ACS among lower-risk patients with chest pain [95]. Several studies have suggested that in young patients with chest pain, a calcium score of zero is not a reliable test to exclude CAD, and adverse events have been shown to occur in up to 6% of acute chest pain patients without coronary artery calcium [96]. The ability of a zero calcium score to allow safe discharge of low-risk acute chest pain patients continues to be actively studied [97-100]. CT Chest CT Chest Nongated chest CT, although useful for evaluating noncardiac thoracic pathology, does not currently have a role in the evaluation of possible ACS, although perfusion defects can be seen on contrast-enhanced nongated chest CT in patients with ACS [101,102].

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Chest Pain Possible Acute Coronary Syndrome PCAs

CTA Chest CTA of the chest has a well-established role for evaluating other etiologies that may mimic ACS, such as aortic dissection, acute pericarditis, pneumonia, and pneumothorax [27,103]. Nongated chest CTA intended to evaluate a patient for aortic dissection or pulmonary embolism may depict incidental coronary artery pathology, such as anomalous coronary arteries, obstructive CAD, and involvement of the coronary arteries by aortic dissection [104]. In particular, CTA for aortic dissection or pulmonary embolism may be performed with ECG-gating without specific intent to evaluate the coronary arteries (ie, gating intended to reduce pulsation artifact in the great vessels but the examination not otherwise tailored to the coronary arteries), and in those cases, coronary abnormalities may be even more readily apparent as an unexpected finding. Therefore, there is insufficient evidence to support nongated (or incidentally gated) CTA for the evaluation of ACS. Rb-82 PET/CT Heart A stress PET examination can reliably demonstrate myocardial blood flow using rubidium-82 (Rb-82) or nitrogen- 13 (N-13) ammonia. Limited data are available for PET perfusion studies in the setting of acute chest pain, although there is growing evidence for diagnostic and prognostic applications in chronic coronary disease [105,106]. PET can also document anaerobic metabolism using fluorine-18-2-fluoro-2-deoxy-D-glucose and other metabolic tracers. This technology is less well studied in the workup of the acute chest pain patient but may have a role when combined with CTA [105,107,108]. Meta-analysis has shown PET to demonstrate excellent diagnostic performance when compared with other methods of evaluating ischemic myocardium [109].

Chest Pain Possible Acute Coronary Syndrome PCAs. CTA Chest CTA of the chest has a well-established role for evaluating other etiologies that may mimic ACS, such as aortic dissection, acute pericarditis, pneumonia, and pneumothorax [27,103]. Nongated chest CTA intended to evaluate a patient for aortic dissection or pulmonary embolism may depict incidental coronary artery pathology, such as anomalous coronary arteries, obstructive CAD, and involvement of the coronary arteries by aortic dissection [104]. In particular, CTA for aortic dissection or pulmonary embolism may be performed with ECG-gating without specific intent to evaluate the coronary arteries (ie, gating intended to reduce pulsation artifact in the great vessels but the examination not otherwise tailored to the coronary arteries), and in those cases, coronary abnormalities may be even more readily apparent as an unexpected finding. Therefore, there is insufficient evidence to support nongated (or incidentally gated) CTA for the evaluation of ACS. Rb-82 PET/CT Heart A stress PET examination can reliably demonstrate myocardial blood flow using rubidium-82 (Rb-82) or nitrogen- 13 (N-13) ammonia. Limited data are available for PET perfusion studies in the setting of acute chest pain, although there is growing evidence for diagnostic and prognostic applications in chronic coronary disease [105,106]. PET can also document anaerobic metabolism using fluorine-18-2-fluoro-2-deoxy-D-glucose and other metabolic tracers. This technology is less well studied in the workup of the acute chest pain patient but may have a role when combined with CTA [105,107,108]. Meta-analysis has shown PET to demonstrate excellent diagnostic performance when compared with other methods of evaluating ischemic myocardium [109].

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Chest Pain Possible Acute Coronary Syndrome PCAs

MRI Heart with Function and Inotropic Stress MRI Heart with Function and Inotropic Stress Although early ACS approaches of CMR included high-risk patients and tended to use rest-only CMR, more recent studies have demonstrated high negative predictive value and excellent diagnostic performance in a low- to intermediate-risk cohort when compared with nuclear MPI or stress echocardiography [110,111]. Multiple studies have shown that a vasodilator stress CMR strategy for chest pain patients can allow safe discharge and show similar Chest Pain-Possible Acute Coronary Syndrome clinical performance to other stress perfusion techniques [45,112-114]. However, inotropic stress agents like dobutamine, although useful for the characterization of stable ischemic heart disease [115,116], are relatively contraindicated in patients with recent or active chest pain, and so limited literature exists on the use of inotropic stress MRI for the evaluation of ACS. MRI Heart with Function and Vasodilator Stress Perfusion Although early ACS approaches of CMR included high-risk patients and tended to use rest-only CMR, more recent studies have demonstrated high negative predictive value and excellent diagnostic performance in a low- to intermediate-risk cohort when compared with nuclear MPI or stress echocardiography [110,111]. Multiple studies have shown that a stress CMR strategy for chest pain patients can allow safe discharge and show similar clinical performance to other stress-perfusion techniques [45,112-114]. In particular, CMR has been shown to have similar or better performance to nuclear MPI in determining the degree of ischemic myocardium, which may be an important predictor of outcomes after revascularization [117,118].

Chest Pain Possible Acute Coronary Syndrome PCAs. MRI Heart with Function and Inotropic Stress MRI Heart with Function and Inotropic Stress Although early ACS approaches of CMR included high-risk patients and tended to use rest-only CMR, more recent studies have demonstrated high negative predictive value and excellent diagnostic performance in a low- to intermediate-risk cohort when compared with nuclear MPI or stress echocardiography [110,111]. Multiple studies have shown that a vasodilator stress CMR strategy for chest pain patients can allow safe discharge and show similar Chest Pain-Possible Acute Coronary Syndrome clinical performance to other stress perfusion techniques [45,112-114]. However, inotropic stress agents like dobutamine, although useful for the characterization of stable ischemic heart disease [115,116], are relatively contraindicated in patients with recent or active chest pain, and so limited literature exists on the use of inotropic stress MRI for the evaluation of ACS. MRI Heart with Function and Vasodilator Stress Perfusion Although early ACS approaches of CMR included high-risk patients and tended to use rest-only CMR, more recent studies have demonstrated high negative predictive value and excellent diagnostic performance in a low- to intermediate-risk cohort when compared with nuclear MPI or stress echocardiography [110,111]. Multiple studies have shown that a stress CMR strategy for chest pain patients can allow safe discharge and show similar clinical performance to other stress-perfusion techniques [45,112-114]. In particular, CMR has been shown to have similar or better performance to nuclear MPI in determining the degree of ischemic myocardium, which may be an important predictor of outcomes after revascularization [117,118].

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Chest Pain Possible Acute Coronary Syndrome PCAs

For example, several studies on outpatients with suspected CAD (eg, MR-IMPACT, CE-MARC, MR-INFORM) demonstrated superior performance of stress CMR when compared with nuclear SPECT MPI [119,120] and have recently reported noninferiority when compared with invasive FFR [121]. MRI Heart Function and Morphology MRI Heart Function and Morphology CMR with delayed postcontrast imaging and edema-weighted imaging provides assessment of the size, distribution, and transmural extent of acute or remote MI. Cine CMR has usefulness in demonstrating wall-motion abnormalities, which may accompany acute or chronic ischemic heart disease, and first-pass contrast-enhanced perfusion CMR can demonstrate myocardial perfusion abnormalities [110,111,122-124]. The use of T2-weighted CMR to identify myocardial edema can help predict outcomes in patients with NSTE-ACS without affecting time to catheterization [125]. In addition, CMR has a role in elucidating the cause of myocardial necrosis in patients with elevated cardiac biomarkers presumed to have ACS but with nonobstructive coronary arteries by CT or catheter angiography [126,127]. MRI, like CT, can also identify noncardiac reasons for chest pain. Both contrast-enhanced and nonenhanced time-of-flight angiographic techniques can be used for aortic pathology, and CMR can be used for the evaluation of other mimics of ACS with troponin elevation, including pericarditis, myocarditis, and Takotsubo cardiomyopathy [128,129]. New techniques in CMR, for example, myocardial mapping, may provide additional methods that can be used to evaluate patients with acute chest pain [130,131]. MRA Coronary Arteries Although coronary MR angiography (MRA) has not been established in general practice, both angiographic and phase-contrast flow continue to be developed for coronary artery assessment in research centers [132].

Chest Pain Possible Acute Coronary Syndrome PCAs. For example, several studies on outpatients with suspected CAD (eg, MR-IMPACT, CE-MARC, MR-INFORM) demonstrated superior performance of stress CMR when compared with nuclear SPECT MPI [119,120] and have recently reported noninferiority when compared with invasive FFR [121]. MRI Heart Function and Morphology MRI Heart Function and Morphology CMR with delayed postcontrast imaging and edema-weighted imaging provides assessment of the size, distribution, and transmural extent of acute or remote MI. Cine CMR has usefulness in demonstrating wall-motion abnormalities, which may accompany acute or chronic ischemic heart disease, and first-pass contrast-enhanced perfusion CMR can demonstrate myocardial perfusion abnormalities [110,111,122-124]. The use of T2-weighted CMR to identify myocardial edema can help predict outcomes in patients with NSTE-ACS without affecting time to catheterization [125]. In addition, CMR has a role in elucidating the cause of myocardial necrosis in patients with elevated cardiac biomarkers presumed to have ACS but with nonobstructive coronary arteries by CT or catheter angiography [126,127]. MRI, like CT, can also identify noncardiac reasons for chest pain. Both contrast-enhanced and nonenhanced time-of-flight angiographic techniques can be used for aortic pathology, and CMR can be used for the evaluation of other mimics of ACS with troponin elevation, including pericarditis, myocarditis, and Takotsubo cardiomyopathy [128,129]. New techniques in CMR, for example, myocardial mapping, may provide additional methods that can be used to evaluate patients with acute chest pain [130,131]. MRA Coronary Arteries Although coronary MR angiography (MRA) has not been established in general practice, both angiographic and phase-contrast flow continue to be developed for coronary artery assessment in research centers [132].

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Chest Pain Possible Acute Coronary Syndrome PCAs

Noncontrast angiographic whole-heart acquisition with 3-D steady-state free precession MRI technique can provide imaging of the coronary arteries and is particularly useful in the evaluation of coronary anomalies, bypass graft assessment, and coronary aneurysm formation [133]. Trials have demonstrated high sensitivity and moderate specificity of coronary MRA for the evaluation of obstructive coronary artery stenosis, particularly when used in combination with nonangiographic CMR sequences [119,134]. Future avenues of clinical use include reliable evaluation of coronary artery stenosis and characterization of plaque composition for the identification of vulnerable or high-risk plaques [135]. In patients without ST-segment elevation, positive cardiac biomarkers may nonetheless suggest myocardial necrosis, and the ECG may demonstrate a NSTE ischemic pattern, including ST depression, transient ST-segment elevation, or prominent T-wave inversions [139]. ACS patients with unstable angina may have similar ECG patterns but demonstrate no biomarker evidence of myocardial necrosis (eg, troponin level within normal limits), though biomarker negativity in these patients may grow rarer as high-sensitivity biomarker tests become more widely Chest Pain-Possible Acute Coronary Syndrome Radiography Chest Chest radiography is primarily used for ruling out conditions that may masquerade as acute myocardial ischemia as well as defining secondary findings that may accompany acute MI. Acute pulmonary edema can be seen on chest radiographs without enlargement of the cardiac silhouette in patients with acute MI and no prior history of ischemic damage or associated mitral valve disease. Although chest radiography is insufficient to confirm or exclude the presence of significant CAD, it may be useful in demonstrating clinically important pathology in a significant minority of ACS-suspected patients [31].

Chest Pain Possible Acute Coronary Syndrome PCAs. Noncontrast angiographic whole-heart acquisition with 3-D steady-state free precession MRI technique can provide imaging of the coronary arteries and is particularly useful in the evaluation of coronary anomalies, bypass graft assessment, and coronary aneurysm formation [133]. Trials have demonstrated high sensitivity and moderate specificity of coronary MRA for the evaluation of obstructive coronary artery stenosis, particularly when used in combination with nonangiographic CMR sequences [119,134]. Future avenues of clinical use include reliable evaluation of coronary artery stenosis and characterization of plaque composition for the identification of vulnerable or high-risk plaques [135]. In patients without ST-segment elevation, positive cardiac biomarkers may nonetheless suggest myocardial necrosis, and the ECG may demonstrate a NSTE ischemic pattern, including ST depression, transient ST-segment elevation, or prominent T-wave inversions [139]. ACS patients with unstable angina may have similar ECG patterns but demonstrate no biomarker evidence of myocardial necrosis (eg, troponin level within normal limits), though biomarker negativity in these patients may grow rarer as high-sensitivity biomarker tests become more widely Chest Pain-Possible Acute Coronary Syndrome Radiography Chest Chest radiography is primarily used for ruling out conditions that may masquerade as acute myocardial ischemia as well as defining secondary findings that may accompany acute MI. Acute pulmonary edema can be seen on chest radiographs without enlargement of the cardiac silhouette in patients with acute MI and no prior history of ischemic damage or associated mitral valve disease. Although chest radiography is insufficient to confirm or exclude the presence of significant CAD, it may be useful in demonstrating clinically important pathology in a significant minority of ACS-suspected patients [31].

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Chest Pain Possible Acute Coronary Syndrome PCAs

Other cardiovascular entities, such as aortic aneurysms, aortic dissections, and pulmonary embolism, may be suggested from the chest radiography but with far lower sensitivity than other imaging modalities such as multidetector CT. Noncardiac findings associated with chest pain that can be identified on the chest radiograph include pneumothorax, fractured ribs, pleural effusions, and pneumonia, among others. CTA Coronary Arteries There is no relevant literature regarding the use of CCTA in the evaluation of ACS in high-probability patients. CT Chest CT Chest Nongated chest CT, although useful for evaluating noncardiac thoracic pathology, does not currently have a role in the evaluation of possible ACS, although perfusion defects can be seen on nongated chest CT in patients with ACS [101,102]. CTA Chest CTA of the chest has a well-established role for evaluating other etiologies that may mimic ACS, such as aortic dissection, acute pericarditis, pneumonia, and pneumothorax [27,103]. CT Coronary Calcium There is no relevant literature regarding the use of CT calcium scoring in the evaluation of ACS in high-probability patients. MRA Coronary Arteries There is no relevant literature regarding the use of coronary MRA in the evaluation of ACS in high-risk patients. MRI Heart Function and Morphology The use of T2-weighted CMR to identify myocardial edema can help predict outcomes in patients with NSTE-ACS, without impacting time to catheterization, and a combination of noncontrast and postcontrast resting CMR sequences can help inform prognosis and identify myocardial areas at risk [125,144]. In addition, CMR has a role in elucidating the cause of myocardial necrosis in patients with elevated cardiac biomarkers presumed to have ACS but with nonobstructive coronary arteries by CT or catheter angiography [126-128,145].

Chest Pain Possible Acute Coronary Syndrome PCAs. Other cardiovascular entities, such as aortic aneurysms, aortic dissections, and pulmonary embolism, may be suggested from the chest radiography but with far lower sensitivity than other imaging modalities such as multidetector CT. Noncardiac findings associated with chest pain that can be identified on the chest radiograph include pneumothorax, fractured ribs, pleural effusions, and pneumonia, among others. CTA Coronary Arteries There is no relevant literature regarding the use of CCTA in the evaluation of ACS in high-probability patients. CT Chest CT Chest Nongated chest CT, although useful for evaluating noncardiac thoracic pathology, does not currently have a role in the evaluation of possible ACS, although perfusion defects can be seen on nongated chest CT in patients with ACS [101,102]. CTA Chest CTA of the chest has a well-established role for evaluating other etiologies that may mimic ACS, such as aortic dissection, acute pericarditis, pneumonia, and pneumothorax [27,103]. CT Coronary Calcium There is no relevant literature regarding the use of CT calcium scoring in the evaluation of ACS in high-probability patients. MRA Coronary Arteries There is no relevant literature regarding the use of coronary MRA in the evaluation of ACS in high-risk patients. MRI Heart Function and Morphology The use of T2-weighted CMR to identify myocardial edema can help predict outcomes in patients with NSTE-ACS, without impacting time to catheterization, and a combination of noncontrast and postcontrast resting CMR sequences can help inform prognosis and identify myocardial areas at risk [125,144]. In addition, CMR has a role in elucidating the cause of myocardial necrosis in patients with elevated cardiac biomarkers presumed to have ACS but with nonobstructive coronary arteries by CT or catheter angiography [126-128,145].

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Chest Pain Possible Acute Coronary Syndrome PCAs

MRI Heart with Function and Inotropic Stress There is no relevant literature regarding the use of stress CMR in the evaluation of ACS in high-probability patients. MRI Heart with Function and Vasodilator Stress Perfusion MRI Heart with Function and Vasodilator Stress Perfusion There is no relevant literature regarding the use of stress perfusion CMR in the evaluation of ACS in high- probability patients. Rb-82 PET/CT Heart Rb-82 PET/CT Heart There is no relevant literature regarding the use of stress PET/CT in the evaluation of ACS in high-probability patients. SPECT or SPECT/CT MPI Rest Only There is no relevant literature regarding the use of rest-only MPI in the evaluation of ACS in high-probability patients. Chest Pain-Possible Acute Coronary Syndrome SPECT or SPECT/CT MPI Rest and Stress Noninvasive stress testing with nuclear SPECT-MPI may be helpful in NSTE-ACS patients for risk stratification before discharge in patients with an ischemia-guided strategy. High NSTE-ACS patients (eg, patients with left main disease, age >70, multivessel disease, diabetes mellitus, prior MI or revascularization, or depressed left ventricular function) may benefit from routine revascularization, but low-to intermediate-risk NSTE-ACS patients may receive less benefit from routine revascularization and therefore may benefit from risk stratification according to provocative testing with stress. In particular, nuclear MPI with stress can be used to identify low-risk patients suitable for early discharge [146,147]. US Echocardiography Transthoracic Stress There is no relevant literature regarding the use of stress echocardiography in the evaluation of ACS in high- probability patients.

Chest Pain Possible Acute Coronary Syndrome PCAs. MRI Heart with Function and Inotropic Stress There is no relevant literature regarding the use of stress CMR in the evaluation of ACS in high-probability patients. MRI Heart with Function and Vasodilator Stress Perfusion MRI Heart with Function and Vasodilator Stress Perfusion There is no relevant literature regarding the use of stress perfusion CMR in the evaluation of ACS in high- probability patients. Rb-82 PET/CT Heart Rb-82 PET/CT Heart There is no relevant literature regarding the use of stress PET/CT in the evaluation of ACS in high-probability patients. SPECT or SPECT/CT MPI Rest Only There is no relevant literature regarding the use of rest-only MPI in the evaluation of ACS in high-probability patients. Chest Pain-Possible Acute Coronary Syndrome SPECT or SPECT/CT MPI Rest and Stress Noninvasive stress testing with nuclear SPECT-MPI may be helpful in NSTE-ACS patients for risk stratification before discharge in patients with an ischemia-guided strategy. High NSTE-ACS patients (eg, patients with left main disease, age >70, multivessel disease, diabetes mellitus, prior MI or revascularization, or depressed left ventricular function) may benefit from routine revascularization, but low-to intermediate-risk NSTE-ACS patients may receive less benefit from routine revascularization and therefore may benefit from risk stratification according to provocative testing with stress. In particular, nuclear MPI with stress can be used to identify low-risk patients suitable for early discharge [146,147]. US Echocardiography Transthoracic Stress There is no relevant literature regarding the use of stress echocardiography in the evaluation of ACS in high- probability patients.

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acrac_3193974_0

Hydronephrosis on Prior Imaging Unknown Cause

Hydronephrosis can be classified by cause and by unilateral versus bilateral involvement. Obstructive hydronephrosis can be further classified by level of obstruction, complete versus partial obstruction, and intrinsic versus extrinsic obstruction [1]. Causes of hydronephrosis include urolithiasis, malignant obstruction, stricture, upper urinary tract infection, traumatic or ischemic injury, postradiation changes, retroperitoneal fibrosis, supravesical or bladder dysfunction, bladder outlet obstruction as with prostatic hyperplasia, mechanical compression as with enlarged uterus or pelvic organ prolapse, endometriosis, schistosomiasis, drug effects as with cyclophosphamide or ketamine, vessel-related and/or congenital ureteropelvic junction obstruction, and congenital posterior urethral valves [1-3]. Hydronephrosis also occurs frequently during pregnancy; asymptomatic hydronephrosis occurs in an estimated 70% to 90% of pregnant patients, typically asymmetrically prominent on the right, due to a combination of mechanical obstruction from an enlarged uterus and collecting system smooth muscle relaxation due to progesterone [4]. Approximately 0.2% to 4.7% of pregnant patients experience symptomatic hydronephrosis, with the prevalence higher in advancing trimesters and in multiparous patients [5-9]. Symptomatic hydronephrosis may lead to preterm labor or maternal/fetal death when left untreated [9]. Special Imaging Considerations Scintigraphic diuresis renography (DRG) uses nuclear medicine and the administration of a diuretic to differentiate nonobstructive hydronephrosis from hydronephrosis due to true functional obstruction. Administration of a selected radiotracer such as diethylenetriamine pentaacetic acid (DTPA) or mercaptoacetyltriglycine (MAG3) is used to demonstrate flow during the perfusion, extraction, and excretion phases. Delayed planar imaging can also be performed.

Hydronephrosis on Prior Imaging Unknown Cause. Hydronephrosis can be classified by cause and by unilateral versus bilateral involvement. Obstructive hydronephrosis can be further classified by level of obstruction, complete versus partial obstruction, and intrinsic versus extrinsic obstruction [1]. Causes of hydronephrosis include urolithiasis, malignant obstruction, stricture, upper urinary tract infection, traumatic or ischemic injury, postradiation changes, retroperitoneal fibrosis, supravesical or bladder dysfunction, bladder outlet obstruction as with prostatic hyperplasia, mechanical compression as with enlarged uterus or pelvic organ prolapse, endometriosis, schistosomiasis, drug effects as with cyclophosphamide or ketamine, vessel-related and/or congenital ureteropelvic junction obstruction, and congenital posterior urethral valves [1-3]. Hydronephrosis also occurs frequently during pregnancy; asymptomatic hydronephrosis occurs in an estimated 70% to 90% of pregnant patients, typically asymmetrically prominent on the right, due to a combination of mechanical obstruction from an enlarged uterus and collecting system smooth muscle relaxation due to progesterone [4]. Approximately 0.2% to 4.7% of pregnant patients experience symptomatic hydronephrosis, with the prevalence higher in advancing trimesters and in multiparous patients [5-9]. Symptomatic hydronephrosis may lead to preterm labor or maternal/fetal death when left untreated [9]. Special Imaging Considerations Scintigraphic diuresis renography (DRG) uses nuclear medicine and the administration of a diuretic to differentiate nonobstructive hydronephrosis from hydronephrosis due to true functional obstruction. Administration of a selected radiotracer such as diethylenetriamine pentaacetic acid (DTPA) or mercaptoacetyltriglycine (MAG3) is used to demonstrate flow during the perfusion, extraction, and excretion phases. Delayed planar imaging can also be performed.

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acrac_3193974_1

Hydronephrosis on Prior Imaging Unknown Cause

CT urography (CTU) is an imaging study that is tailored to improve visualization of both the upper and lower urinary tracts. There is variability in the specific parameters, but it usually involves unenhanced images followed by intravenous (IV) contrast-enhanced images, including nephrographic and excretory phases acquired at least 5 minutes after contrast injection. Alternatively, a split-bolus technique uses an initial loading dose of IV contrast and Reprint requests to: [email protected] Hydronephrosis on Prior Imaging-Unknown Cause then obtains a combined nephrographic-excretory phase after a second IV contrast dose; some sites include arterial phase. CTU should use thin-slice acquisition. Reconstruction methods commonly include maximum intensity projection or 3-D volume rendering. For the purposes of this document, we make a distinction between CTU and CT abdomen and pelvis without and with IV contrast. CT abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts and without both the precontrast and excretory phases. MR urography (MRU) is also tailored to improve imaging of the urinary system. Unenhanced MRU relies upon heavily T2-weighted imaging of the intrinsic high signal intensity from urine for evaluation of the urinary tract. IV contrast is administered to provide additional information regarding obstruction, urothelial thickening, focal lesions, and stones. A contrast-enhanced T1-weighted series should include corticomedullary, nephrographic, and excretory phase. Thin-slice acquisition and multiplanar imaging should be obtained. For the purposes of this document, we make a distinction between MRU and MRI abdomen and pelvis without and with IV contrast.

Hydronephrosis on Prior Imaging Unknown Cause. CT urography (CTU) is an imaging study that is tailored to improve visualization of both the upper and lower urinary tracts. There is variability in the specific parameters, but it usually involves unenhanced images followed by intravenous (IV) contrast-enhanced images, including nephrographic and excretory phases acquired at least 5 minutes after contrast injection. Alternatively, a split-bolus technique uses an initial loading dose of IV contrast and Reprint requests to: [email protected] Hydronephrosis on Prior Imaging-Unknown Cause then obtains a combined nephrographic-excretory phase after a second IV contrast dose; some sites include arterial phase. CTU should use thin-slice acquisition. Reconstruction methods commonly include maximum intensity projection or 3-D volume rendering. For the purposes of this document, we make a distinction between CTU and CT abdomen and pelvis without and with IV contrast. CT abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts and without both the precontrast and excretory phases. MR urography (MRU) is also tailored to improve imaging of the urinary system. Unenhanced MRU relies upon heavily T2-weighted imaging of the intrinsic high signal intensity from urine for evaluation of the urinary tract. IV contrast is administered to provide additional information regarding obstruction, urothelial thickening, focal lesions, and stones. A contrast-enhanced T1-weighted series should include corticomedullary, nephrographic, and excretory phase. Thin-slice acquisition and multiplanar imaging should be obtained. For the purposes of this document, we make a distinction between MRU and MRI abdomen and pelvis without and with IV contrast.

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Hydronephrosis on Prior Imaging Unknown Cause

MRI abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts, without both the precontrast and excretory phases, and without heavily T2-weighted images of the urinary tract. OR Discussion of Procedures by Variant Variant 1: Adult. Asymptomatic unilateral hydronephrosis with unknown cause. Initial imaging. Please note that this variant describes initial imaging evaluation after the discovery, by imaging or otherwise, of asymptomatic unilateral hydronephrosis with unknown cause. The choice of initial imaging in this situation is dependent on clinical context and on the information available from the means of hydronephrosis discovery (eg, CT, MR, ultrasound [US]). CT Abdomen and Pelvis With IV Contrast Although there is limited evidence to support the use of CT abdomen and pelvis with IV contrast (separate from CTU) for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause, it may be useful in this setting in some clinical situations. A more comprehensive evaluation can often be achieved with CT, MRU, or renal scintigraphy. CT Abdomen and Pelvis Without and With IV Contrast There is limited evidence to support the use of CT abdomen and pelvis without and with IV contrast (separate from CTU) for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause, and more comprehensive evaluation with CT, MRU, or renal scintigraphy is preferred. CT Abdomen and Pelvis Without IV Contrast Although there is limited evidence to support the use of CT abdomen and pelvis without IV contrast (separate from CTU) for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause, it may be useful in this setting for some clinical situations. A more comprehensive evaluation can often be achieved with CT, MRU, or renal scintigraphy.

Hydronephrosis on Prior Imaging Unknown Cause. MRI abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts, without both the precontrast and excretory phases, and without heavily T2-weighted images of the urinary tract. OR Discussion of Procedures by Variant Variant 1: Adult. Asymptomatic unilateral hydronephrosis with unknown cause. Initial imaging. Please note that this variant describes initial imaging evaluation after the discovery, by imaging or otherwise, of asymptomatic unilateral hydronephrosis with unknown cause. The choice of initial imaging in this situation is dependent on clinical context and on the information available from the means of hydronephrosis discovery (eg, CT, MR, ultrasound [US]). CT Abdomen and Pelvis With IV Contrast Although there is limited evidence to support the use of CT abdomen and pelvis with IV contrast (separate from CTU) for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause, it may be useful in this setting in some clinical situations. A more comprehensive evaluation can often be achieved with CT, MRU, or renal scintigraphy. CT Abdomen and Pelvis Without and With IV Contrast There is limited evidence to support the use of CT abdomen and pelvis without and with IV contrast (separate from CTU) for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause, and more comprehensive evaluation with CT, MRU, or renal scintigraphy is preferred. CT Abdomen and Pelvis Without IV Contrast Although there is limited evidence to support the use of CT abdomen and pelvis without IV contrast (separate from CTU) for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause, it may be useful in this setting for some clinical situations. A more comprehensive evaluation can often be achieved with CT, MRU, or renal scintigraphy.

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Hydronephrosis on Prior Imaging Unknown Cause

CT abdomen and pelvis without IV contrast is particularly useful when obstructive urolithiasis is a primary concern. CT Abdomen With IV Contrast There is limited evidence to support the use of CT abdomen with IV contrast for initial imaging (separate from CTU) of patients with asymptomatic unilateral hydronephrosis with unknown cause. Hydronephrosis on Prior Imaging-Unknown Cause CT Abdomen Without and With IV Contrast There is limited evidence to support the use of CT abdomen without and with IV contrast (separate from CTU) for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause. CT Abdomen Without IV Contrast There is limited evidence to support the use of CT abdomen without IV contrast (separate from CTU) for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause. CTU Without and With IV Contrast Although there is limited evidence to support the use of CTU without and with IV contrast for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause, CTU is useful for investigating the etiology of hydronephrosis. CTU provides a near-comprehensive evaluation of the genitourinary tract including both morphological and functional information. DTPA Renal Scan DRG is the de facto standard of care in diagnosis of renal obstruction [10] and can be used to determine whether obstructive uropathy is truly present in cases of incidentally noted hydronephrosis [11]. However, tubular tracers (eg, MAG3 and 123I) are much more efficiently extracted by the kidney than DTPA, and washout is therefore easier to evaluate with tubular tracers. Use of DTPA for diuretic renography may result in an equivocal or false-positive diuretic study compared with MAG3, particularly in patients with reduced function, and is not favored for imaging only studies [11,12].

Hydronephrosis on Prior Imaging Unknown Cause. CT abdomen and pelvis without IV contrast is particularly useful when obstructive urolithiasis is a primary concern. CT Abdomen With IV Contrast There is limited evidence to support the use of CT abdomen with IV contrast for initial imaging (separate from CTU) of patients with asymptomatic unilateral hydronephrosis with unknown cause. Hydronephrosis on Prior Imaging-Unknown Cause CT Abdomen Without and With IV Contrast There is limited evidence to support the use of CT abdomen without and with IV contrast (separate from CTU) for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause. CT Abdomen Without IV Contrast There is limited evidence to support the use of CT abdomen without IV contrast (separate from CTU) for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause. CTU Without and With IV Contrast Although there is limited evidence to support the use of CTU without and with IV contrast for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause, CTU is useful for investigating the etiology of hydronephrosis. CTU provides a near-comprehensive evaluation of the genitourinary tract including both morphological and functional information. DTPA Renal Scan DRG is the de facto standard of care in diagnosis of renal obstruction [10] and can be used to determine whether obstructive uropathy is truly present in cases of incidentally noted hydronephrosis [11]. However, tubular tracers (eg, MAG3 and 123I) are much more efficiently extracted by the kidney than DTPA, and washout is therefore easier to evaluate with tubular tracers. Use of DTPA for diuretic renography may result in an equivocal or false-positive diuretic study compared with MAG3, particularly in patients with reduced function, and is not favored for imaging only studies [11,12].

3193974

acrac_3193974_4

Hydronephrosis on Prior Imaging Unknown Cause

DRG with DTPA is useful for estimating single-kidney glomerular filtration rate (GFR), although it may somewhat overestimate global GFR in the setting of obstructive hydronephrosis [13]. Fluoroscopy Antegrade Pyelography There is limited evidence to support the use of fluoroscopic antegrade pyelography for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause. Fluoroscopy Voiding Cystourethrography There is limited evidence to support the use of fluoroscopic voiding cystourethrography for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause. MAG3 Renal Scan DRG is the de facto standard of care in diagnosis of renal obstruction [10] and can be used to determine whether obstructive uropathy is truly present in cases of incidentally noted hydronephrosis [11]. Tubular tracers (eg, MAG3 and 123I) are much more efficiently extracted by the kidney than DTPA, and washout is therefore easier to evaluate with tubular tracers. Tubular tracers such as MAG3 are favored over the use of DTPA for imaging only studies, because DTPA diuretic renography may result in an equivocal or false-positive diuretic study compared with MAG3, particularly in patients with reduced function [11,12]. MRI Abdomen and Pelvis Without and With IV Contrast Although there is limited evidence to support the use of MRI abdomen and pelvis without and with IV contrast (separate from MRU) for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause, it may be useful in this setting in some clinical situations. A more comprehensive evaluation can often be achieved with CT, MRU, or renal scintigraphy. MRI Abdomen and Pelvis Without IV Contrast There is limited evidence to support the use of MRI abdomen and pelvis without IV contrast (separate from MRU) for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause.

Hydronephrosis on Prior Imaging Unknown Cause. DRG with DTPA is useful for estimating single-kidney glomerular filtration rate (GFR), although it may somewhat overestimate global GFR in the setting of obstructive hydronephrosis [13]. Fluoroscopy Antegrade Pyelography There is limited evidence to support the use of fluoroscopic antegrade pyelography for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause. Fluoroscopy Voiding Cystourethrography There is limited evidence to support the use of fluoroscopic voiding cystourethrography for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause. MAG3 Renal Scan DRG is the de facto standard of care in diagnosis of renal obstruction [10] and can be used to determine whether obstructive uropathy is truly present in cases of incidentally noted hydronephrosis [11]. Tubular tracers (eg, MAG3 and 123I) are much more efficiently extracted by the kidney than DTPA, and washout is therefore easier to evaluate with tubular tracers. Tubular tracers such as MAG3 are favored over the use of DTPA for imaging only studies, because DTPA diuretic renography may result in an equivocal or false-positive diuretic study compared with MAG3, particularly in patients with reduced function [11,12]. MRI Abdomen and Pelvis Without and With IV Contrast Although there is limited evidence to support the use of MRI abdomen and pelvis without and with IV contrast (separate from MRU) for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause, it may be useful in this setting in some clinical situations. A more comprehensive evaluation can often be achieved with CT, MRU, or renal scintigraphy. MRI Abdomen and Pelvis Without IV Contrast There is limited evidence to support the use of MRI abdomen and pelvis without IV contrast (separate from MRU) for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause.

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acrac_3193974_5

Hydronephrosis on Prior Imaging Unknown Cause

MRI Abdomen Without and With IV Contrast There is limited evidence to support the use of MRI abdomen without and with IV contrast (separate from MRU) for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause. MRI Abdomen Without IV Contrast There is limited evidence to support the use of MRI abdomen without IV contrast (separate from MRU) for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause. MRU Without and With IV Contrast There is some evidence for use of MRU without and with IV contrast for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause. Although it can be performed independently, MRU can also be performed at the time of structural MRI. MRU without and with IV contrast is useful for investigating Hydronephrosis on Prior Imaging-Unknown Cause the etiology of hydronephrosis and, in combination with anatomical imaging, can provide a near-comprehensive evaluation of the genitourinary tract including both morphological and functional information. In a prospective study, Claudon et al [14] compared MRU without and with IV contrast with MAG3 or DTPA DRG in 295 adult and pediatric patients with hydronephrosis and clinical suspicion for chronic or intermittent obstruction, including both symptomatic and asymptomatic patients and excluding those with acute urinary obstruction or solitary or transplant kidney. They reported equivalence of MRU with renal scintigraphy for diagnostic evaluation of split renal function in moderately dilated kidneys, with a standard deviation of approximately 12% between the two; for severely dilated kidneys, they note a mean underestimation by MRU of split renal function by 4%. They conclude that substitution of DRG by MRU is acceptable for moderately dilated kidneys but remains questionable for severely dilated kidneys.

Hydronephrosis on Prior Imaging Unknown Cause. MRI Abdomen Without and With IV Contrast There is limited evidence to support the use of MRI abdomen without and with IV contrast (separate from MRU) for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause. MRI Abdomen Without IV Contrast There is limited evidence to support the use of MRI abdomen without IV contrast (separate from MRU) for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause. MRU Without and With IV Contrast There is some evidence for use of MRU without and with IV contrast for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause. Although it can be performed independently, MRU can also be performed at the time of structural MRI. MRU without and with IV contrast is useful for investigating Hydronephrosis on Prior Imaging-Unknown Cause the etiology of hydronephrosis and, in combination with anatomical imaging, can provide a near-comprehensive evaluation of the genitourinary tract including both morphological and functional information. In a prospective study, Claudon et al [14] compared MRU without and with IV contrast with MAG3 or DTPA DRG in 295 adult and pediatric patients with hydronephrosis and clinical suspicion for chronic or intermittent obstruction, including both symptomatic and asymptomatic patients and excluding those with acute urinary obstruction or solitary or transplant kidney. They reported equivalence of MRU with renal scintigraphy for diagnostic evaluation of split renal function in moderately dilated kidneys, with a standard deviation of approximately 12% between the two; for severely dilated kidneys, they note a mean underestimation by MRU of split renal function by 4%. They conclude that substitution of DRG by MRU is acceptable for moderately dilated kidneys but remains questionable for severely dilated kidneys.

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Hydronephrosis on Prior Imaging Unknown Cause

Notably, most of the included patients were children <2 years of age, and the MRU technique used included a diuretic component. In a prospective study of 13 people without and 15 people with hydronephrosis, Wang et al [13] reported significant correlation between MRU and DRG estimations of single-kidney GFR and that MRU is comparable to DRG for estimation of GFR in the setting of hydronephrosis. They note that both MRU and DRG may somewhat overestimate global GFR in the setting of obstructive hydronephrosis. MRU Without IV Contrast Although there is limited evidence to support the use of MRU without IV contrast for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause, MRU without IV contrast is, in general, preferred over CTU in patients with renal impairment [15]. MRU without IV contrast is useful for investigating the etiology of hydronephrosis and can be combined with anatomical imaging to provide more information than anatomical imaging alone but does not provide the level of functional imaging attainable with MRU without and with IV contrast. Radiography Abdomen and Pelvis There is limited evidence to support the use of radiography of the abdomen and pelvis for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause. Radiography of the abdomen and pelvis is not useful in this setting, and CT is more sensitive for obstructive urolithiasis. Radiography Intravenous Urography There is limited evidence to support the use of radiography with IV urography (IVU) (also referred to as IV pyelogram [IVP]) for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause. US Abdomen There is relatively limited evidence to support the use of US of the abdomen for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause.

Hydronephrosis on Prior Imaging Unknown Cause. Notably, most of the included patients were children <2 years of age, and the MRU technique used included a diuretic component. In a prospective study of 13 people without and 15 people with hydronephrosis, Wang et al [13] reported significant correlation between MRU and DRG estimations of single-kidney GFR and that MRU is comparable to DRG for estimation of GFR in the setting of hydronephrosis. They note that both MRU and DRG may somewhat overestimate global GFR in the setting of obstructive hydronephrosis. MRU Without IV Contrast Although there is limited evidence to support the use of MRU without IV contrast for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause, MRU without IV contrast is, in general, preferred over CTU in patients with renal impairment [15]. MRU without IV contrast is useful for investigating the etiology of hydronephrosis and can be combined with anatomical imaging to provide more information than anatomical imaging alone but does not provide the level of functional imaging attainable with MRU without and with IV contrast. Radiography Abdomen and Pelvis There is limited evidence to support the use of radiography of the abdomen and pelvis for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause. Radiography of the abdomen and pelvis is not useful in this setting, and CT is more sensitive for obstructive urolithiasis. Radiography Intravenous Urography There is limited evidence to support the use of radiography with IV urography (IVU) (also referred to as IV pyelogram [IVP]) for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause. US Abdomen There is relatively limited evidence to support the use of US of the abdomen for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause.

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Hydronephrosis on Prior Imaging Unknown Cause

Although US allows evaluation for increased renal echogenicity, which is nonspecific, but can be helpful in assessing for chronic kidney disease, US abdomen is a less comprehensive examination of the genitourinary system than CT or MRU, renal scintigraphy, or US color Doppler kidneys and bladder retroperitoneal. US Color Doppler Kidneys and Bladder Retroperitoneal Although there is limited evidence to support the use of US of the abdomen for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause, it may be useful in this setting in some clinical situations. Although renal US can identify and grade hydronephrosis, it is less useful for identification of etiology. US does allow evaluation for increased renal echogenicity, which, although nonspecific, can be helpful in assessing for chronic kidney disease. Additionally, US color Doppler kidneys and bladder retroperitoneal allows evaluation of ureteral jets, bladder distension, and postvoid residual bladder volume and can allow measurement of the prostate to evaluate for prostatomegaly. Unilateral elevation of resistive indices is nonspecific but can be seen in the setting of obstruction. However, more comprehensive evaluation can often be achieved with CT, MRU, or renal scintigraphy. Variant 2: Adult. Asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause. Initial imaging. Please note that this variant describes initial imaging evaluation after the discovery, by imaging or otherwise, of asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause. The choice of initial imaging in this situation is dependent on clinical context and on the information available from the means of hydronephrosis discovery (eg, CT, MR, US). Hydronephrosis on Prior Imaging-Unknown Cause

Hydronephrosis on Prior Imaging Unknown Cause. Although US allows evaluation for increased renal echogenicity, which is nonspecific, but can be helpful in assessing for chronic kidney disease, US abdomen is a less comprehensive examination of the genitourinary system than CT or MRU, renal scintigraphy, or US color Doppler kidneys and bladder retroperitoneal. US Color Doppler Kidneys and Bladder Retroperitoneal Although there is limited evidence to support the use of US of the abdomen for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause, it may be useful in this setting in some clinical situations. Although renal US can identify and grade hydronephrosis, it is less useful for identification of etiology. US does allow evaluation for increased renal echogenicity, which, although nonspecific, can be helpful in assessing for chronic kidney disease. Additionally, US color Doppler kidneys and bladder retroperitoneal allows evaluation of ureteral jets, bladder distension, and postvoid residual bladder volume and can allow measurement of the prostate to evaluate for prostatomegaly. Unilateral elevation of resistive indices is nonspecific but can be seen in the setting of obstruction. However, more comprehensive evaluation can often be achieved with CT, MRU, or renal scintigraphy. Variant 2: Adult. Asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause. Initial imaging. Please note that this variant describes initial imaging evaluation after the discovery, by imaging or otherwise, of asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause. The choice of initial imaging in this situation is dependent on clinical context and on the information available from the means of hydronephrosis discovery (eg, CT, MR, US). Hydronephrosis on Prior Imaging-Unknown Cause

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acrac_3193974_8

Hydronephrosis on Prior Imaging Unknown Cause

CT Abdomen and Pelvis With IV Contrast Although there is limited evidence to support the use of CT abdomen and pelvis with IV contrast (separate from CTU) for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause, it may be useful in this setting in some clinical situations. The addition of IV contrast is helpful in assessment for pelvic masses as a cause of bilateral hydronephrosis. More comprehensive evaluation can often be achieved with CT, MRU, or renal scintigraphy. CT Abdomen and Pelvis Without and With IV Contrast There is limited evidence to support the use of CT abdomen and pelvis without and with IV contrast (separate from CTU) for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause, and more comprehensive evaluation with CT, MRU, or renal scintigraphy is preferred. CT Abdomen and Pelvis Without IV Contrast Although there is limited evidence to support the use of CT abdomen and pelvis without IV contrast (separate from CTU) for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause, it may be useful in the setting of some clinical situations. A more comprehensive evaluation can often be achieved with CT, MRU, or renal scintigraphy. CT abdomen and pelvis without IV contrast is particularly useful when obstructive urolithiasis is a primary concern, although this etiology is less likely in the setting of bilateral hydronephrosis. CT Abdomen With IV Contrast There is limited evidence to support the use of CT abdomen with IV contrast (separate from CTU) for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause.

Hydronephrosis on Prior Imaging Unknown Cause. CT Abdomen and Pelvis With IV Contrast Although there is limited evidence to support the use of CT abdomen and pelvis with IV contrast (separate from CTU) for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause, it may be useful in this setting in some clinical situations. The addition of IV contrast is helpful in assessment for pelvic masses as a cause of bilateral hydronephrosis. More comprehensive evaluation can often be achieved with CT, MRU, or renal scintigraphy. CT Abdomen and Pelvis Without and With IV Contrast There is limited evidence to support the use of CT abdomen and pelvis without and with IV contrast (separate from CTU) for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause, and more comprehensive evaluation with CT, MRU, or renal scintigraphy is preferred. CT Abdomen and Pelvis Without IV Contrast Although there is limited evidence to support the use of CT abdomen and pelvis without IV contrast (separate from CTU) for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause, it may be useful in the setting of some clinical situations. A more comprehensive evaluation can often be achieved with CT, MRU, or renal scintigraphy. CT abdomen and pelvis without IV contrast is particularly useful when obstructive urolithiasis is a primary concern, although this etiology is less likely in the setting of bilateral hydronephrosis. CT Abdomen With IV Contrast There is limited evidence to support the use of CT abdomen with IV contrast (separate from CTU) for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause.

3193974

acrac_3193974_9

Hydronephrosis on Prior Imaging Unknown Cause

CT Abdomen Without and With IV Contrast There is limited evidence to support the use of CT abdomen without and with IV contrast (separate from CTU) for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause. CT Abdomen Without IV Contrast There is limited evidence to support the use of CT abdomen without IV contrast (separate from CTU) for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause. CTU Without and With IV Contrast Although there is limited evidence to support the use of CTU without and with IV contrast for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause, CTU is useful for investigating the etiology of hydronephrosis. CTU provides a near- comprehensive evaluation of the genitourinary tract including both morphological and functional information. DTPA Renal Scan DRG is the de facto standard of care in diagnosis of renal obstruction [10] and can be used to determine whether obstructive uropathy is truly present in cases of incidentally noted hydronephrosis [11]. However, tubular tracers (eg, MAG3 and 123I) are much more efficiently extracted by the kidney than DTPA, and washout is therefore easier to evaluate with tubular tracers. Use of DTPA for diuretic renography may result in an equivocal or false-positive diuretic study compared with MAG3, particularly in patients with reduced function, and is not favored for imaging only studies [11,12]. DRG with DTPA is useful for estimating single-kidney GFR, although it may somewhat overestimate global GFR in the setting of obstructive hydronephrosis [13].

Hydronephrosis on Prior Imaging Unknown Cause. CT Abdomen Without and With IV Contrast There is limited evidence to support the use of CT abdomen without and with IV contrast (separate from CTU) for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause. CT Abdomen Without IV Contrast There is limited evidence to support the use of CT abdomen without IV contrast (separate from CTU) for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause. CTU Without and With IV Contrast Although there is limited evidence to support the use of CTU without and with IV contrast for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause, CTU is useful for investigating the etiology of hydronephrosis. CTU provides a near- comprehensive evaluation of the genitourinary tract including both morphological and functional information. DTPA Renal Scan DRG is the de facto standard of care in diagnosis of renal obstruction [10] and can be used to determine whether obstructive uropathy is truly present in cases of incidentally noted hydronephrosis [11]. However, tubular tracers (eg, MAG3 and 123I) are much more efficiently extracted by the kidney than DTPA, and washout is therefore easier to evaluate with tubular tracers. Use of DTPA for diuretic renography may result in an equivocal or false-positive diuretic study compared with MAG3, particularly in patients with reduced function, and is not favored for imaging only studies [11,12]. DRG with DTPA is useful for estimating single-kidney GFR, although it may somewhat overestimate global GFR in the setting of obstructive hydronephrosis [13].

3193974

acrac_3193974_10

Hydronephrosis on Prior Imaging Unknown Cause

Fluoroscopy Antegrade Pyelography There is limited evidence to support the use of fluoroscopic antegrade pyelography for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause. Fluoroscopy Voiding Cystourethrography There is limited evidence to support the use of fluoroscopic voiding cystourethrography for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause. Hydronephrosis on Prior Imaging-Unknown Cause MAG3 Renal Scan DRG is the de facto standard of care in diagnosis of renal obstruction [10] and can be used to determine whether obstructive uropathy is truly present in cases of incidentally noted hydronephrosis or in suspected obstruction of renal transplant [11]. Further, DRG with urethral catheter has been suggested for patients with bilateral hydronephrosis or hydroureteronephrosis with postvoid residual <150 mL to help differentiate potential etiologies [2]. Tubular tracers (eg, MAG3 and 123I) are much more efficiently extracted by the kidney than DTPA, and washout is therefore easier to evaluate with tubular tracers. Tubular tracers such as MAG3 are favored over the use of DTPA for imaging only studies, because DTPA DRG may result in an equivocal or false-positive diuretic study compared with MAG3, particularly in patients with reduced function [11,12]. MRI Abdomen and Pelvis Without and With IV Contrast Although there is limited evidence to support the use of MRI abdomen and pelvis without and with IV contrast (separate from MRU) for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause, it may be useful in this setting in some clinical situations. More comprehensive evaluation can often be achieved with CT, MRU, or renal scintigraphy.

Hydronephrosis on Prior Imaging Unknown Cause. Fluoroscopy Antegrade Pyelography There is limited evidence to support the use of fluoroscopic antegrade pyelography for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause. Fluoroscopy Voiding Cystourethrography There is limited evidence to support the use of fluoroscopic voiding cystourethrography for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause. Hydronephrosis on Prior Imaging-Unknown Cause MAG3 Renal Scan DRG is the de facto standard of care in diagnosis of renal obstruction [10] and can be used to determine whether obstructive uropathy is truly present in cases of incidentally noted hydronephrosis or in suspected obstruction of renal transplant [11]. Further, DRG with urethral catheter has been suggested for patients with bilateral hydronephrosis or hydroureteronephrosis with postvoid residual <150 mL to help differentiate potential etiologies [2]. Tubular tracers (eg, MAG3 and 123I) are much more efficiently extracted by the kidney than DTPA, and washout is therefore easier to evaluate with tubular tracers. Tubular tracers such as MAG3 are favored over the use of DTPA for imaging only studies, because DTPA DRG may result in an equivocal or false-positive diuretic study compared with MAG3, particularly in patients with reduced function [11,12]. MRI Abdomen and Pelvis Without and With IV Contrast Although there is limited evidence to support the use of MRI abdomen and pelvis without and with IV contrast (separate from MRU) for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause, it may be useful in this setting in some clinical situations. More comprehensive evaluation can often be achieved with CT, MRU, or renal scintigraphy.

3193974

acrac_3193974_11

Hydronephrosis on Prior Imaging Unknown Cause

MRI Abdomen and Pelvis Without IV Contrast There is limited evidence to support the use of MRI abdomen and pelvis without IV contrast (separate from MRU) for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause. MRI Abdomen Without and With IV Contrast There is limited evidence to support the use of MRI abdomen without and with IV contrast (separate from MRU) for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause. MRI Abdomen Without IV Contrast There is limited evidence to support the use of MRI abdomen without IV contrast (separate from MRU) for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause. MRU Without and With IV Contrast There is some evidence for use of MRU without and with IV contrast for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause. Although it can be performed independently, MRU can also be performed at the time of structural MRI. MRU without and with IV contrast is useful for investigating the etiology of hydronephrosis and in combination with anatomical imaging can provide a near-comprehensive evaluation of the genitourinary tract including both morphological and functional information. In a prospective study, Claudon et al [14] compared MRU without and with IV contrast with MAG3 or DTPA DRG in 295 adult and pediatric patients with hydronephrosis and clinical suspicion for chronic or intermittent obstruction, including both symptomatic and asymptomatic patients and excluding those with acute urinary obstruction or solitary or transplant kidney.

Hydronephrosis on Prior Imaging Unknown Cause. MRI Abdomen and Pelvis Without IV Contrast There is limited evidence to support the use of MRI abdomen and pelvis without IV contrast (separate from MRU) for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause. MRI Abdomen Without and With IV Contrast There is limited evidence to support the use of MRI abdomen without and with IV contrast (separate from MRU) for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause. MRI Abdomen Without IV Contrast There is limited evidence to support the use of MRI abdomen without IV contrast (separate from MRU) for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause. MRU Without and With IV Contrast There is some evidence for use of MRU without and with IV contrast for initial imaging of patients with asymptomatic unilateral hydronephrosis with unknown cause. Although it can be performed independently, MRU can also be performed at the time of structural MRI. MRU without and with IV contrast is useful for investigating the etiology of hydronephrosis and in combination with anatomical imaging can provide a near-comprehensive evaluation of the genitourinary tract including both morphological and functional information. In a prospective study, Claudon et al [14] compared MRU without and with IV contrast with MAG3 or DTPA DRG in 295 adult and pediatric patients with hydronephrosis and clinical suspicion for chronic or intermittent obstruction, including both symptomatic and asymptomatic patients and excluding those with acute urinary obstruction or solitary or transplant kidney.

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acrac_3193974_12

Hydronephrosis on Prior Imaging Unknown Cause

They reported equivalence of MRU with renal scintigraphy for diagnostic evaluation of split renal function in moderately dilated kidneys, with a standard deviation of approximately 12% between the two; for severely dilated kidneys, they note a mean underestimation by MRU of split renal function by 4%. They conclude that substitution of DRG by MRU is acceptable for moderately dilated kidneys but remains questionable for severely dilated kidneys. Notably, most of the included patients were children <2 years of age, and the MRU technique used included a diuretic component. In a prospective study of 13 people without and 15 people with hydronephrosis, Wang et al [13] reported significant correlation between MRU and DRG estimations of single-kidney GFR and that MRU is comparable to DRG for estimation of GFR in the setting of hydronephrosis. They note that both MRU and DRG may somewhat overestimate global GFR in the setting of obstructive hydronephrosis. MRU Without IV Contrast Although there is limited evidence to support the use of MRU without IV contrast for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause, MRU without IV contrast is, in general, preferred over CTU in patients with renal impairment [15]. MRU without IV contrast is useful for investigating the etiology of hydronephrosis and can be combined with anatomical Hydronephrosis on Prior Imaging-Unknown Cause imaging to provide more information than anatomical imaging alone but does not provide the level of functional imaging attainable with MRU without and with IV contrast. Radiography Abdomen and Pelvis There is limited evidence to support the use of radiography of the abdomen and pelvis for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause. Radiography of the abdomen and pelvis is not considered useful in this setting.

Hydronephrosis on Prior Imaging Unknown Cause. They reported equivalence of MRU with renal scintigraphy for diagnostic evaluation of split renal function in moderately dilated kidneys, with a standard deviation of approximately 12% between the two; for severely dilated kidneys, they note a mean underestimation by MRU of split renal function by 4%. They conclude that substitution of DRG by MRU is acceptable for moderately dilated kidneys but remains questionable for severely dilated kidneys. Notably, most of the included patients were children <2 years of age, and the MRU technique used included a diuretic component. In a prospective study of 13 people without and 15 people with hydronephrosis, Wang et al [13] reported significant correlation between MRU and DRG estimations of single-kidney GFR and that MRU is comparable to DRG for estimation of GFR in the setting of hydronephrosis. They note that both MRU and DRG may somewhat overestimate global GFR in the setting of obstructive hydronephrosis. MRU Without IV Contrast Although there is limited evidence to support the use of MRU without IV contrast for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause, MRU without IV contrast is, in general, preferred over CTU in patients with renal impairment [15]. MRU without IV contrast is useful for investigating the etiology of hydronephrosis and can be combined with anatomical Hydronephrosis on Prior Imaging-Unknown Cause imaging to provide more information than anatomical imaging alone but does not provide the level of functional imaging attainable with MRU without and with IV contrast. Radiography Abdomen and Pelvis There is limited evidence to support the use of radiography of the abdomen and pelvis for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause. Radiography of the abdomen and pelvis is not considered useful in this setting.

3193974

acrac_3193974_13

Hydronephrosis on Prior Imaging Unknown Cause

Radiography Intravenous Urography There is limited evidence to support the use of radiography with IVU (also referred to as IVP) for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause. US Abdomen There is relatively limited evidence to support the use of US of the abdomen for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause. Although US allows evaluation for increased renal echogenicity, which is nonspecific, but can be helpful in assessing for chronic kidney disease, US abdomen is a less comprehensive examination of the genitourinary system than CT, MRU, renal scintigraphy, or US color Doppler kidneys and bladder retroperitoneal. US Color Doppler Kidneys and Bladder Retroperitoneal Although there is limited evidence to support the use of US of the abdomen for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause, it may be useful in this setting in some clinical situations. Although renal US can identify and grade hydronephrosis, it is less useful for identification of etiology. US does allow evaluation for increased renal echogenicity, which, although nonspecific, can be helpful in assessing for chronic kidney disease. Additionally, US Color Doppler kidneys and bladder retroperitoneal allows evaluation of ureteral jets, bladder distension, and postvoid residual bladder volume and can allow measurement of the prostate to evaluate for prostatomegaly. Elevation of resistive indices is nonspecific but can be seen in the setting of obstruction. However, more comprehensive evaluation can often be achieved with CT, MRU, or renal scintigraphy. Variant 3: Adult. Symptomatic hydronephrosis with unknown cause. Initial imaging.

Hydronephrosis on Prior Imaging Unknown Cause. Radiography Intravenous Urography There is limited evidence to support the use of radiography with IVU (also referred to as IVP) for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause. US Abdomen There is relatively limited evidence to support the use of US of the abdomen for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause. Although US allows evaluation for increased renal echogenicity, which is nonspecific, but can be helpful in assessing for chronic kidney disease, US abdomen is a less comprehensive examination of the genitourinary system than CT, MRU, renal scintigraphy, or US color Doppler kidneys and bladder retroperitoneal. US Color Doppler Kidneys and Bladder Retroperitoneal Although there is limited evidence to support the use of US of the abdomen for initial imaging of patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause, it may be useful in this setting in some clinical situations. Although renal US can identify and grade hydronephrosis, it is less useful for identification of etiology. US does allow evaluation for increased renal echogenicity, which, although nonspecific, can be helpful in assessing for chronic kidney disease. Additionally, US Color Doppler kidneys and bladder retroperitoneal allows evaluation of ureteral jets, bladder distension, and postvoid residual bladder volume and can allow measurement of the prostate to evaluate for prostatomegaly. Elevation of resistive indices is nonspecific but can be seen in the setting of obstruction. However, more comprehensive evaluation can often be achieved with CT, MRU, or renal scintigraphy. Variant 3: Adult. Symptomatic hydronephrosis with unknown cause. Initial imaging.

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acrac_3193974_14

Hydronephrosis on Prior Imaging Unknown Cause

Please note that this variant describes initial imaging evaluation after the discovery, by imaging or otherwise, of symptomatic hydronephrosis with unknown cause. The choice of initial imaging in this situation is dependent on clinical context and on the information available from the means of hydronephrosis discovery (eg, CT, MR, US). Pathan et al [22] reviewed 651 patients with point-of-care US (POCUS) and CT in the setting of renal colic, finding that moderate to severe hydronephrosis on POCUS examination in patients with moderate or high risk of ureteric calculi, provided a more definitive answer regarding the presence of a stone without the need for high-dose CT scanning. In such patients, they advised a low-dose CT scan if the size and location of the stone is desired to plan surgical management. Pathan et al [22] reviewed 651 patients with POCUS and CT in the setting of renal colic, finding that moderate to severe hydronephrosis on POCUS examination in patients with moderate or high risk of ureteric calculi, provided a more definitive answer regarding the presence of a stone without the need for high-dose CT scanning. In such patients, they advised a low-dose CT scan if the size and location of the stone is desired to plan surgical management. CT Abdomen and Pelvis Without IV Contrast Although there is some evidence to support the use of CT abdomen and pelvis without IV contrast (separate from CTU) for initial imaging of patients with symptomatic hydronephrosis with unknown cause, it may be useful in this setting in some clinical situations. A more comprehensive evaluation can often be achieved with CT, MRU, or renal scintigraphy. In particular, this procedure is suitable for evaluating symptomatic patients when US is inconclusive [24]. CT abdomen and pelvis without IV contrast is particularly useful when obstructive urolithiasis is a primary concern.

Hydronephrosis on Prior Imaging Unknown Cause. Please note that this variant describes initial imaging evaluation after the discovery, by imaging or otherwise, of symptomatic hydronephrosis with unknown cause. The choice of initial imaging in this situation is dependent on clinical context and on the information available from the means of hydronephrosis discovery (eg, CT, MR, US). Pathan et al [22] reviewed 651 patients with point-of-care US (POCUS) and CT in the setting of renal colic, finding that moderate to severe hydronephrosis on POCUS examination in patients with moderate or high risk of ureteric calculi, provided a more definitive answer regarding the presence of a stone without the need for high-dose CT scanning. In such patients, they advised a low-dose CT scan if the size and location of the stone is desired to plan surgical management. Pathan et al [22] reviewed 651 patients with POCUS and CT in the setting of renal colic, finding that moderate to severe hydronephrosis on POCUS examination in patients with moderate or high risk of ureteric calculi, provided a more definitive answer regarding the presence of a stone without the need for high-dose CT scanning. In such patients, they advised a low-dose CT scan if the size and location of the stone is desired to plan surgical management. CT Abdomen and Pelvis Without IV Contrast Although there is some evidence to support the use of CT abdomen and pelvis without IV contrast (separate from CTU) for initial imaging of patients with symptomatic hydronephrosis with unknown cause, it may be useful in this setting in some clinical situations. A more comprehensive evaluation can often be achieved with CT, MRU, or renal scintigraphy. In particular, this procedure is suitable for evaluating symptomatic patients when US is inconclusive [24]. CT abdomen and pelvis without IV contrast is particularly useful when obstructive urolithiasis is a primary concern.

3193974

acrac_3193974_15

Hydronephrosis on Prior Imaging Unknown Cause

CT can be useful in patients with renal colic and moderate to severe hydronephrosis by US, because these patients can be at higher risk of stone passage failure [16], although some authors suggest CT should be reserved in renal colic patients for when US is nondiagnostic or when an alternative diagnosis is suspected [17]. In cases of suspected infection, it can be difficult to distinguish pyonephrosis from hydronephrosis even by CT, although collecting system content density may be helpful [18,19]; notably, recent contrast administration can also affect this density. Pathan et al [22] reviewed 651 patients with POCUS and CT in the setting of renal colic, finding that moderate to severe hydronephrosis on POCUS examination in patients with moderate or high risk of ureteric calculi provided a more definitive answer regarding the presence of a stone without the need for high-dose CT scanning. In such Hydronephrosis on Prior Imaging-Unknown Cause patients, they advised a low-dose CT scan if the size and location of the stone is desired to plan surgical management. CT Abdomen With IV Contrast There is limited evidence to support the use of CT abdomen with IV contrast (separate from CTU) for initial imaging of patients with symptomatic hydronephrosis with unknown cause. CT Abdomen Without and With IV Contrast There is limited evidence to support the use of CT abdomen without and with IV contrast (separate from CTU) for initial imaging of patients with symptomatic hydronephrosis with unknown cause. CT Abdomen Without IV Contrast There is limited evidence to support the use of CT abdomen without IV contrast (separate from CTU) for initial imaging of patients with symptomatic hydronephrosis with unknown cause.

Hydronephrosis on Prior Imaging Unknown Cause. CT can be useful in patients with renal colic and moderate to severe hydronephrosis by US, because these patients can be at higher risk of stone passage failure [16], although some authors suggest CT should be reserved in renal colic patients for when US is nondiagnostic or when an alternative diagnosis is suspected [17]. In cases of suspected infection, it can be difficult to distinguish pyonephrosis from hydronephrosis even by CT, although collecting system content density may be helpful [18,19]; notably, recent contrast administration can also affect this density. Pathan et al [22] reviewed 651 patients with POCUS and CT in the setting of renal colic, finding that moderate to severe hydronephrosis on POCUS examination in patients with moderate or high risk of ureteric calculi provided a more definitive answer regarding the presence of a stone without the need for high-dose CT scanning. In such Hydronephrosis on Prior Imaging-Unknown Cause patients, they advised a low-dose CT scan if the size and location of the stone is desired to plan surgical management. CT Abdomen With IV Contrast There is limited evidence to support the use of CT abdomen with IV contrast (separate from CTU) for initial imaging of patients with symptomatic hydronephrosis with unknown cause. CT Abdomen Without and With IV Contrast There is limited evidence to support the use of CT abdomen without and with IV contrast (separate from CTU) for initial imaging of patients with symptomatic hydronephrosis with unknown cause. CT Abdomen Without IV Contrast There is limited evidence to support the use of CT abdomen without IV contrast (separate from CTU) for initial imaging of patients with symptomatic hydronephrosis with unknown cause.

3193974

acrac_3193974_16

Hydronephrosis on Prior Imaging Unknown Cause

CTU Without and With IV Contrast Although there is relatively limited evidence to support the use of CTU without and with IV contrast for initial imaging of patients with symptomatic hydronephrosis with unknown cause, CTU is useful for investigating the etiology of hydronephrosis. CTU provides a near-comprehensive evaluation of the genitourinary tract including both morphological and functional information. In a prospective study evaluating 70 patients with renal colic or hematuria, CTU was performed after hydronephrosis was confirmed with US and was able to detect 100% of renal calculi but was less sensitive in detection of other causes of obstruction [28]. DTPA Renal Scan DRG is the de facto standard of care in diagnosis of renal obstruction [10] and can be used to determine whether obstructive uropathy is truly present in cases of incidentally noted hydronephrosis [11]. However, tubular tracers (eg, MAG3 and 123I) are much more efficiently extracted by the kidney than DTPA, and washout is therefore easier to evaluate with tubular tracers. Use of DTPA for diuretic renography may result in an equivocal or false-positive diuretic study compared with MAG3, particularly in patients with reduced function, and is not favored for imaging only studies [11,12]. DRG with DTPA is useful for estimating single-kidney GFR, although it may somewhat overestimate global GFR in the setting of obstructive hydronephrosis [13]. Fluoroscopy Antegrade Pyelography There is limited evidence to support the use of fluoroscopic antegrade pyelography for initial imaging of patients with symptomatic hydronephrosis with unknown cause. Fluoroscopy Voiding Cystourethrography There is limited evidence to support the use of fluoroscopic voiding cystourethrography for initial imaging of patients with symptomatic hydronephrosis with unknown cause.

Hydronephrosis on Prior Imaging Unknown Cause. CTU Without and With IV Contrast Although there is relatively limited evidence to support the use of CTU without and with IV contrast for initial imaging of patients with symptomatic hydronephrosis with unknown cause, CTU is useful for investigating the etiology of hydronephrosis. CTU provides a near-comprehensive evaluation of the genitourinary tract including both morphological and functional information. In a prospective study evaluating 70 patients with renal colic or hematuria, CTU was performed after hydronephrosis was confirmed with US and was able to detect 100% of renal calculi but was less sensitive in detection of other causes of obstruction [28]. DTPA Renal Scan DRG is the de facto standard of care in diagnosis of renal obstruction [10] and can be used to determine whether obstructive uropathy is truly present in cases of incidentally noted hydronephrosis [11]. However, tubular tracers (eg, MAG3 and 123I) are much more efficiently extracted by the kidney than DTPA, and washout is therefore easier to evaluate with tubular tracers. Use of DTPA for diuretic renography may result in an equivocal or false-positive diuretic study compared with MAG3, particularly in patients with reduced function, and is not favored for imaging only studies [11,12]. DRG with DTPA is useful for estimating single-kidney GFR, although it may somewhat overestimate global GFR in the setting of obstructive hydronephrosis [13]. Fluoroscopy Antegrade Pyelography There is limited evidence to support the use of fluoroscopic antegrade pyelography for initial imaging of patients with symptomatic hydronephrosis with unknown cause. Fluoroscopy Voiding Cystourethrography There is limited evidence to support the use of fluoroscopic voiding cystourethrography for initial imaging of patients with symptomatic hydronephrosis with unknown cause.

3193974

acrac_3193974_17

Hydronephrosis on Prior Imaging Unknown Cause

MAG3 Renal Scan DRG is the de facto standard of care in diagnosis of renal obstruction [10] and can be used to determine whether obstructive uropathy is truly present in cases of incidentally noted hydronephrosis or in suspected obstruction of renal transplant [11]. Further, DRG with urethral catheter has been suggested for patients with bilateral hydronephrosis or hydroureteronephrosis with postvoid residual <150 mL to help differentiate potential etiologies [2]. Tubular tracers (eg, MAG3 and 123I) are much more efficiently extracted by the kidney than DTPA, and washout is therefore easier to evaluate with tubular tracers. Tubular tracers such as MAG3 are favored over the use of DTPA for imaging only studies, because DTPA DRG may result in an equivocal or false-positive diuretic study compared with MAG3, particularly in patients with reduced function [11,12]. Hydronephrosis on Prior Imaging-Unknown Cause MRI Abdomen and Pelvis Without and With IV Contrast Although there is limited evidence to support the use of MRI abdomen and pelvis without and with IV contrast (separate from MRU) for initial imaging of patients with symptomatic hydronephrosis with unknown cause, it may be useful in this setting in some clinical situations. A more comprehensive evaluation can often be achieved with CT, MRU, or renal scintigraphy. MRI Abdomen and Pelvis Without IV Contrast Although there is limited evidence to support the use of MRI abdomen and pelvis without IV contrast (separate from MRU) for initial imaging of patients with symptomatic hydronephrosis with unknown cause, it may be useful in this setting in some clinical situations. More comprehensive evaluation can often be achieved with CT, MRU, or renal scintigraphy. MRI Abdomen Without and With IV Contrast There is limited evidence to support the use of MRI abdomen without and with IV contrast (separate from MRU) for initial imaging of patients with symptomatic hydronephrosis with unknown cause.

Hydronephrosis on Prior Imaging Unknown Cause. MAG3 Renal Scan DRG is the de facto standard of care in diagnosis of renal obstruction [10] and can be used to determine whether obstructive uropathy is truly present in cases of incidentally noted hydronephrosis or in suspected obstruction of renal transplant [11]. Further, DRG with urethral catheter has been suggested for patients with bilateral hydronephrosis or hydroureteronephrosis with postvoid residual <150 mL to help differentiate potential etiologies [2]. Tubular tracers (eg, MAG3 and 123I) are much more efficiently extracted by the kidney than DTPA, and washout is therefore easier to evaluate with tubular tracers. Tubular tracers such as MAG3 are favored over the use of DTPA for imaging only studies, because DTPA DRG may result in an equivocal or false-positive diuretic study compared with MAG3, particularly in patients with reduced function [11,12]. Hydronephrosis on Prior Imaging-Unknown Cause MRI Abdomen and Pelvis Without and With IV Contrast Although there is limited evidence to support the use of MRI abdomen and pelvis without and with IV contrast (separate from MRU) for initial imaging of patients with symptomatic hydronephrosis with unknown cause, it may be useful in this setting in some clinical situations. A more comprehensive evaluation can often be achieved with CT, MRU, or renal scintigraphy. MRI Abdomen and Pelvis Without IV Contrast Although there is limited evidence to support the use of MRI abdomen and pelvis without IV contrast (separate from MRU) for initial imaging of patients with symptomatic hydronephrosis with unknown cause, it may be useful in this setting in some clinical situations. More comprehensive evaluation can often be achieved with CT, MRU, or renal scintigraphy. MRI Abdomen Without and With IV Contrast There is limited evidence to support the use of MRI abdomen without and with IV contrast (separate from MRU) for initial imaging of patients with symptomatic hydronephrosis with unknown cause.

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acrac_3193974_18

Hydronephrosis on Prior Imaging Unknown Cause

MRI Abdomen Without IV Contrast There is limited evidence to support the use of MRI abdomen without IV contrast (separate from MRU) for initial imaging of patients with symptomatic hydronephrosis with unknown cause. MRU Without and With IV Contrast There is some evidence for use of MRU without and with IV contrast for initial imaging of patients with symptomatic hydronephrosis with unknown cause. Although it can be performed independently, MRU can also be performed at the time of structural MRI. MRU without and with IV contrast is useful for investigating the etiology of hydronephrosis and in combination with anatomical imaging can provide a near-comprehensive evaluation of the genitourinary tract including both morphological and functional information. Multiple studies report similar findings between MRU and DRG for diagnostic evaluation of hydronephrosis. In a prospective study, Claudon et al [14] compared MRU without and with IV contrast with MAG3 or DTPA DRG in 295 adult and pediatric patients with hydronephrosis and clinical suspicion for chronic or intermittent obstruction, including both symptomatic and asymptomatic patients and excluding those with acute urinary obstruction or solitary or transplant kidney. They reported equivalence of MRU with renal scintigraphy for diagnostic evaluation of split renal function in moderately dilated kidneys, with a standard deviation of approximately 12% between the two; for severely dilated kidneys, they note a mean underestimation by MRU of split renal function by 4%. They conclude that substitution of DRG by MRU is acceptable for moderately dilated kidneys but remains questionable for severely dilated kidneys. Notably, most of the included patients were children <2 years of age, and the MRU technique used included a diuretic component.

Hydronephrosis on Prior Imaging Unknown Cause. MRI Abdomen Without IV Contrast There is limited evidence to support the use of MRI abdomen without IV contrast (separate from MRU) for initial imaging of patients with symptomatic hydronephrosis with unknown cause. MRU Without and With IV Contrast There is some evidence for use of MRU without and with IV contrast for initial imaging of patients with symptomatic hydronephrosis with unknown cause. Although it can be performed independently, MRU can also be performed at the time of structural MRI. MRU without and with IV contrast is useful for investigating the etiology of hydronephrosis and in combination with anatomical imaging can provide a near-comprehensive evaluation of the genitourinary tract including both morphological and functional information. Multiple studies report similar findings between MRU and DRG for diagnostic evaluation of hydronephrosis. In a prospective study, Claudon et al [14] compared MRU without and with IV contrast with MAG3 or DTPA DRG in 295 adult and pediatric patients with hydronephrosis and clinical suspicion for chronic or intermittent obstruction, including both symptomatic and asymptomatic patients and excluding those with acute urinary obstruction or solitary or transplant kidney. They reported equivalence of MRU with renal scintigraphy for diagnostic evaluation of split renal function in moderately dilated kidneys, with a standard deviation of approximately 12% between the two; for severely dilated kidneys, they note a mean underestimation by MRU of split renal function by 4%. They conclude that substitution of DRG by MRU is acceptable for moderately dilated kidneys but remains questionable for severely dilated kidneys. Notably, most of the included patients were children <2 years of age, and the MRU technique used included a diuretic component.

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Hydronephrosis on Prior Imaging Unknown Cause

In a prospective study of 13 people without and 15 people with hydronephrosis, Wang et al [13] reported significant correlation between MRU and DRG estimations of single-kidney GFR and that MRU is comparable to DRG for estimation of GFR in the setting of hydronephrosis. They note that both MRU and DRG may somewhat overestimate global GFR in the setting of obstructive hydronephrosis. MRU Without IV Contrast There is some evidence for use of MRU without IV contrast for initial imaging of patients with symptomatic hydronephrosis with unknown cause. Although it can be performed independently, MRU can also be performed at the time of structural MRI. MRU without IV contrast is useful for investigating the etiology of hydronephrosis and can be combined with anatomical imaging to provide more information than anatomical imaging alone but does not provide the level of functional imaging attainable with MRU without and with IV contrast. Hydronephrosis on Prior Imaging-Unknown Cause In a prospective study of 55 patients with hydronephrosis detected on US for urologic symptoms, excluding patients with abnormal renal function given contraindication for IVU, Muthusami et al [30] compared static heavily T2- weighted MRU to reference IVU and determined that MRU had high sensitivity and specificity for detecting (95% and 100%, respectively) and grading (Spearman correlation coefficient 0.92) hydronephrosis, as well as identifying the location of obstruction (90% and 99%, respectively) if present. The authors conclude that static MRU can replace IVU when the latter is contraindicated or technically difficult. The authors note that MRU sensitivity for hydronephrosis grading increased with grade of obstruction. MRU can be useful in patients with renal colic and concern for obstruction.

Hydronephrosis on Prior Imaging Unknown Cause. In a prospective study of 13 people without and 15 people with hydronephrosis, Wang et al [13] reported significant correlation between MRU and DRG estimations of single-kidney GFR and that MRU is comparable to DRG for estimation of GFR in the setting of hydronephrosis. They note that both MRU and DRG may somewhat overestimate global GFR in the setting of obstructive hydronephrosis. MRU Without IV Contrast There is some evidence for use of MRU without IV contrast for initial imaging of patients with symptomatic hydronephrosis with unknown cause. Although it can be performed independently, MRU can also be performed at the time of structural MRI. MRU without IV contrast is useful for investigating the etiology of hydronephrosis and can be combined with anatomical imaging to provide more information than anatomical imaging alone but does not provide the level of functional imaging attainable with MRU without and with IV contrast. Hydronephrosis on Prior Imaging-Unknown Cause In a prospective study of 55 patients with hydronephrosis detected on US for urologic symptoms, excluding patients with abnormal renal function given contraindication for IVU, Muthusami et al [30] compared static heavily T2- weighted MRU to reference IVU and determined that MRU had high sensitivity and specificity for detecting (95% and 100%, respectively) and grading (Spearman correlation coefficient 0.92) hydronephrosis, as well as identifying the location of obstruction (90% and 99%, respectively) if present. The authors conclude that static MRU can replace IVU when the latter is contraindicated or technically difficult. The authors note that MRU sensitivity for hydronephrosis grading increased with grade of obstruction. MRU can be useful in patients with renal colic and concern for obstruction.

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Hydronephrosis on Prior Imaging Unknown Cause

Semins et al [31], in a prospective study of 22 patients with renal colic, concluded that noncontrast half-Fourier acquisition single-shot turbo spin-echo MRU can reliably detect presence of upper tract obstruction using visualization of a stone and secondary signs of obstruction; using CT as the reference standard, the combination of stone or perinephric fluid and ureteral dilation gave MRU a sensitivity of 84 %, specificity of 100 %, and accuracy of 86 % (95 % CI 0.72-1.0). Radiography Abdomen and Pelvis There is relatively limited evidence to support the use of radiography of the abdomen and pelvis for initial imaging of patients with symptomatic hydronephrosis with unknown cause. CT is more sensitive for obstructive urolithiasis. Innes et al [32] performed a retrospective multicenter observational cohort study of 1,026 patients with renal colic, finding that adding radiography to screening for hydronephrosis (in this study, by CT) increased sensitivity in all stone categories, specifically from 39% to 68% for large stones and from 60% to 82% for interventional stones. They conclude that this level of sensitivity may be sufficient to reassure physicians about a renal colic diagnosis in the setting of known hydronephrosis without CT imaging for many patients. In a retrospective study of 939 patients with renal colic, Abdel-Gawad et al [33] reported that KUB had limited sensitivity of 53% to 62% and specificity of 67% to 69% for the detection of ureteral calculi. Notably, 90% of stones are radio-opaque, consisting of calcium oxalate, calcium phosphate, and struvite. Although KUB may be comparatively insensitive for stones <4 mm and those in the mid and distal ureters, its use may improve stone detection rates at the margins where obstruction is not readily demonstrated with US [34]. Some studies of patients with renal colic have investigated the combination of radiography and US.

Hydronephrosis on Prior Imaging Unknown Cause. Semins et al [31], in a prospective study of 22 patients with renal colic, concluded that noncontrast half-Fourier acquisition single-shot turbo spin-echo MRU can reliably detect presence of upper tract obstruction using visualization of a stone and secondary signs of obstruction; using CT as the reference standard, the combination of stone or perinephric fluid and ureteral dilation gave MRU a sensitivity of 84 %, specificity of 100 %, and accuracy of 86 % (95 % CI 0.72-1.0). Radiography Abdomen and Pelvis There is relatively limited evidence to support the use of radiography of the abdomen and pelvis for initial imaging of patients with symptomatic hydronephrosis with unknown cause. CT is more sensitive for obstructive urolithiasis. Innes et al [32] performed a retrospective multicenter observational cohort study of 1,026 patients with renal colic, finding that adding radiography to screening for hydronephrosis (in this study, by CT) increased sensitivity in all stone categories, specifically from 39% to 68% for large stones and from 60% to 82% for interventional stones. They conclude that this level of sensitivity may be sufficient to reassure physicians about a renal colic diagnosis in the setting of known hydronephrosis without CT imaging for many patients. In a retrospective study of 939 patients with renal colic, Abdel-Gawad et al [33] reported that KUB had limited sensitivity of 53% to 62% and specificity of 67% to 69% for the detection of ureteral calculi. Notably, 90% of stones are radio-opaque, consisting of calcium oxalate, calcium phosphate, and struvite. Although KUB may be comparatively insensitive for stones <4 mm and those in the mid and distal ureters, its use may improve stone detection rates at the margins where obstruction is not readily demonstrated with US [34]. Some studies of patients with renal colic have investigated the combination of radiography and US.

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Hydronephrosis on Prior Imaging Unknown Cause

Some of these have shown that combining US findings with complementary KUB improved the sensitivity for urolithiasis and had acceptable specificity when compared with either modality alone [34]. In a prospective study of 206 patients with renal colic and suspected urolithiasis, Faget et al [35] found that the combination of radiograph of the abdomen and pelvis and US enabled identification of 50% of the stones that had been identified via CT, and 68% of the stones treated by urological procedures. Radiography Intravenous Urography There is limited evidence to support the use of radiography with IVU (also referred to as IVP) for initial imaging of patients with symptomatic hydronephrosis with unknown cause. Historically, IVP was used to evaluate hydronephrosis, but this study is considered obsolete in many settings [6]. US Abdomen There is relatively limited evidence to support the use of US of the abdomen for initial imaging of patients with symptomatic hydronephrosis with unknown cause. Although US allows evaluation for increased renal echogenicity, which is nonspecific but can be helpful in assessing for chronic kidney disease, US Abdomen is a less comprehensive examination of the genitourinary system than CT, MRU, renal scintigraphy, or US Color Doppler Kidneys and Bladder Retroperitoneal. US Color Doppler Kidneys and Bladder Retroperitoneal There is substantial literature on the use of US of the kidneys in the setting of renal colic, including for initial imaging of patients with symptomatic hydronephrosis with unknown cause, and it may be useful in this setting in some clinical situations. Although renal US can identify and grade hydronephrosis, it is less useful for identification of etiology. US does allow evaluation for increased renal echogenicity, which, although nonspecific, can be helpful in assessing for chronic kidney disease.

Hydronephrosis on Prior Imaging Unknown Cause. Some of these have shown that combining US findings with complementary KUB improved the sensitivity for urolithiasis and had acceptable specificity when compared with either modality alone [34]. In a prospective study of 206 patients with renal colic and suspected urolithiasis, Faget et al [35] found that the combination of radiograph of the abdomen and pelvis and US enabled identification of 50% of the stones that had been identified via CT, and 68% of the stones treated by urological procedures. Radiography Intravenous Urography There is limited evidence to support the use of radiography with IVU (also referred to as IVP) for initial imaging of patients with symptomatic hydronephrosis with unknown cause. Historically, IVP was used to evaluate hydronephrosis, but this study is considered obsolete in many settings [6]. US Abdomen There is relatively limited evidence to support the use of US of the abdomen for initial imaging of patients with symptomatic hydronephrosis with unknown cause. Although US allows evaluation for increased renal echogenicity, which is nonspecific but can be helpful in assessing for chronic kidney disease, US Abdomen is a less comprehensive examination of the genitourinary system than CT, MRU, renal scintigraphy, or US Color Doppler Kidneys and Bladder Retroperitoneal. US Color Doppler Kidneys and Bladder Retroperitoneal There is substantial literature on the use of US of the kidneys in the setting of renal colic, including for initial imaging of patients with symptomatic hydronephrosis with unknown cause, and it may be useful in this setting in some clinical situations. Although renal US can identify and grade hydronephrosis, it is less useful for identification of etiology. US does allow evaluation for increased renal echogenicity, which, although nonspecific, can be helpful in assessing for chronic kidney disease.

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Hydronephrosis on Prior Imaging Unknown Cause

Additionally, US color Doppler kidneys and bladder retroperitoneal allows evaluation of ureteral jets, bladder distension, and postvoid residual bladder volume and can allow measurement of the prostate to evaluate for prostatomegaly. Unilateral elevation of resistive indices is nonspecific but can be seen in the setting of obstruction. However, more comprehensive evaluation can often be achieved with CT, MRU, or renal scintigraphy. Hydronephrosis on Prior Imaging-Unknown Cause If the degree of hydronephrosis is unknown in a patient with hydronephrosis and renal colic, US may be useful to determine degree of hydronephrosis and therefore the likelihood of symptomatic renal stone [36]. Multiple reports indicate the diagnosis of obstructing stone can be made without further imaging after identification of hydronephrosis [37] or urolithiasis [33] in patients with renal colic. A meta-analysis by Wong et al [36] found that in patients with renal colic, moderate or greater hydronephrosis on POCUS was highly specific (94.4%) for presence of symptomatic renal stone, although they noted that severe hydronephrosis is rare and should prompt consideration of alternate causes. Similarly, Taylor et al [38] found in a study of 483 patients that US finding of either at least stones or moderate to severe hydronephrosis was 97% sensitive and 28.1% specific in predicting need for urologic intervention, noting that all 3 cases with severe hydronephrosis underwent intervention. An additional study evaluating 384 patients with unilateral flank pain found that the degree of hydronephrosis was strongly correlated with the number of calculi but weakly correlated with the size of the calculus [39].

Hydronephrosis on Prior Imaging Unknown Cause. Additionally, US color Doppler kidneys and bladder retroperitoneal allows evaluation of ureteral jets, bladder distension, and postvoid residual bladder volume and can allow measurement of the prostate to evaluate for prostatomegaly. Unilateral elevation of resistive indices is nonspecific but can be seen in the setting of obstruction. However, more comprehensive evaluation can often be achieved with CT, MRU, or renal scintigraphy. Hydronephrosis on Prior Imaging-Unknown Cause If the degree of hydronephrosis is unknown in a patient with hydronephrosis and renal colic, US may be useful to determine degree of hydronephrosis and therefore the likelihood of symptomatic renal stone [36]. Multiple reports indicate the diagnosis of obstructing stone can be made without further imaging after identification of hydronephrosis [37] or urolithiasis [33] in patients with renal colic. A meta-analysis by Wong et al [36] found that in patients with renal colic, moderate or greater hydronephrosis on POCUS was highly specific (94.4%) for presence of symptomatic renal stone, although they noted that severe hydronephrosis is rare and should prompt consideration of alternate causes. Similarly, Taylor et al [38] found in a study of 483 patients that US finding of either at least stones or moderate to severe hydronephrosis was 97% sensitive and 28.1% specific in predicting need for urologic intervention, noting that all 3 cases with severe hydronephrosis underwent intervention. An additional study evaluating 384 patients with unilateral flank pain found that the degree of hydronephrosis was strongly correlated with the number of calculi but weakly correlated with the size of the calculus [39].

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Hydronephrosis on Prior Imaging Unknown Cause

Innes et al [16] report that patients with renal colic and with absent to mild hydronephrosis were deemed less likely to have stone passage failure and therefore do not need further imaging, although they note that CT can be useful in the setting of renal colic with moderate to severe hydronephrosis by US because these patients can be at higher risk of stone passage failure. CT is also better able to identify nonurolithiasis findings requiring additional management than US [25]. Pathan et al [22] reviewed 651 patients with POCUS and CT in the setting of renal colic, finding that moderate to severe hydronephrosis on POCUS examination in patients with moderate or high risk of ureteric calculi, provided a more definitive answer regarding the presence of a stone without the need for high-dose CT scanning. In such patients, they advised a low-dose CT scan if the size and location of the stone is desired to plan surgical management. One prospective study of 46 patients with renal colic, documented ureteral stones, and identifiable ureterovesical jet investigated differences in color Doppler US after oral hydration between these presumed obstructed ureters and their nonobstructed contralateral counterparts, finding significant differences of jet frequency, duration, and peak velocity [41]. Renal and ureteral US with color Doppler can identify calculi as well as hydronephrosis in patients with renal colic, although patients who undergo US for initial evaluation are at increased likelihood of undergoing additional imaging [17]. In a prospective study of 206 patients with renal colic and suspected urolithiasis, Faget et al [35] found that the combination of radiography of the abdomen and pelvis and US enabled identification of 50% of the stones that had been identified via CT and 68% of the stones treated by urological procedures. Variant 4: Adult. Asymptomatic hydronephrosis in a pregnant patient with unknown cause. Initial imaging.

Hydronephrosis on Prior Imaging Unknown Cause. Innes et al [16] report that patients with renal colic and with absent to mild hydronephrosis were deemed less likely to have stone passage failure and therefore do not need further imaging, although they note that CT can be useful in the setting of renal colic with moderate to severe hydronephrosis by US because these patients can be at higher risk of stone passage failure. CT is also better able to identify nonurolithiasis findings requiring additional management than US [25]. Pathan et al [22] reviewed 651 patients with POCUS and CT in the setting of renal colic, finding that moderate to severe hydronephrosis on POCUS examination in patients with moderate or high risk of ureteric calculi, provided a more definitive answer regarding the presence of a stone without the need for high-dose CT scanning. In such patients, they advised a low-dose CT scan if the size and location of the stone is desired to plan surgical management. One prospective study of 46 patients with renal colic, documented ureteral stones, and identifiable ureterovesical jet investigated differences in color Doppler US after oral hydration between these presumed obstructed ureters and their nonobstructed contralateral counterparts, finding significant differences of jet frequency, duration, and peak velocity [41]. Renal and ureteral US with color Doppler can identify calculi as well as hydronephrosis in patients with renal colic, although patients who undergo US for initial evaluation are at increased likelihood of undergoing additional imaging [17]. In a prospective study of 206 patients with renal colic and suspected urolithiasis, Faget et al [35] found that the combination of radiography of the abdomen and pelvis and US enabled identification of 50% of the stones that had been identified via CT and 68% of the stones treated by urological procedures. Variant 4: Adult. Asymptomatic hydronephrosis in a pregnant patient with unknown cause. Initial imaging.

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Hydronephrosis on Prior Imaging Unknown Cause

Please note that this variant describes initial imaging evaluation after the discovery, by imaging or otherwise, of asymptomatic hydronephrosis in a pregnant patient with unknown cause. The choice of initial imaging in this situation is dependent on clinical context and on the information available from the means of hydronephrosis discovery (eg, CT, MR, US). CT Abdomen and Pelvis With IV Contrast There is limited evidence to support the use of CT abdomen and pelvis with IV contrast (separate from CTU) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. CT Abdomen and Pelvis Without and With IV Contrast There is limited evidence to support the use of CT abdomen and pelvis without and with IV contrast (separate from CTU) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. Hydronephrosis on Prior Imaging-Unknown Cause CT Abdomen and Pelvis Without IV Contrast There is limited evidence to support the use of CT abdomen and pelvis without IV contrast (separate from CTU) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. CT Abdomen With IV Contrast There is limited evidence to support the use of CT abdomen with IV contrast (separate from CTU) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. CT Abdomen Without and With IV Contrast There is limited evidence to support the use of CT abdomen without and with IV contrast (separate from CTU) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. CT Abdomen Without IV Contrast There is limited evidence to support the use of CT abdomen without IV contrast (separate from CTU) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause.

Hydronephrosis on Prior Imaging Unknown Cause. Please note that this variant describes initial imaging evaluation after the discovery, by imaging or otherwise, of asymptomatic hydronephrosis in a pregnant patient with unknown cause. The choice of initial imaging in this situation is dependent on clinical context and on the information available from the means of hydronephrosis discovery (eg, CT, MR, US). CT Abdomen and Pelvis With IV Contrast There is limited evidence to support the use of CT abdomen and pelvis with IV contrast (separate from CTU) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. CT Abdomen and Pelvis Without and With IV Contrast There is limited evidence to support the use of CT abdomen and pelvis without and with IV contrast (separate from CTU) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. Hydronephrosis on Prior Imaging-Unknown Cause CT Abdomen and Pelvis Without IV Contrast There is limited evidence to support the use of CT abdomen and pelvis without IV contrast (separate from CTU) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. CT Abdomen With IV Contrast There is limited evidence to support the use of CT abdomen with IV contrast (separate from CTU) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. CT Abdomen Without and With IV Contrast There is limited evidence to support the use of CT abdomen without and with IV contrast (separate from CTU) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. CT Abdomen Without IV Contrast There is limited evidence to support the use of CT abdomen without IV contrast (separate from CTU) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause.

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Hydronephrosis on Prior Imaging Unknown Cause

CTU Without and With IV Contrast There is limited evidence to support the use of CTU without and with IV contrast for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. DTPA Renal Scan Although DRG is the de facto standard of care in diagnosis of renal obstruction [10] and can be used to determine whether obstructive uropathy is truly present in cases of incidentally noted hydronephrosis or in suspected obstruction of renal transplant [11], DRG is not preferred for initial imaging in pregnant patients. Note that use of DTPA for diuretic renography may result in an equivocal or false-positive diuretic study compared with MAG3, particularly in patients with reduced function, and is not favored [11,12]. DRG with DTPA can also be used to estimate single-kidney GFR but may somewhat overestimate global GFR in the setting of obstructive hydronephrosis [13]. Fluoroscopy Antegrade Pyelography There is limited evidence to support the use of fluoroscopic antegrade pyelography for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. Fluoroscopy Voiding Cystourethrography There is limited evidence to support the use of fluoroscopic voiding cystourethrography for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. MAG3 Renal Scan Although DRG is the de facto standard of care in diagnosis of renal obstruction [10] and can be used to determine whether obstructive uropathy is truly present in cases of incidentally noted hydronephrosis or in suspected obstruction of renal transplant [11], DRG is not preferred for initial imaging in pregnant patients. MRI Abdomen and Pelvis Without and With IV Contrast There is limited evidence to support the use of MRI abdomen and pelvis without and with IV contrast (separate from MRU) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause.

Hydronephrosis on Prior Imaging Unknown Cause. CTU Without and With IV Contrast There is limited evidence to support the use of CTU without and with IV contrast for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. DTPA Renal Scan Although DRG is the de facto standard of care in diagnosis of renal obstruction [10] and can be used to determine whether obstructive uropathy is truly present in cases of incidentally noted hydronephrosis or in suspected obstruction of renal transplant [11], DRG is not preferred for initial imaging in pregnant patients. Note that use of DTPA for diuretic renography may result in an equivocal or false-positive diuretic study compared with MAG3, particularly in patients with reduced function, and is not favored [11,12]. DRG with DTPA can also be used to estimate single-kidney GFR but may somewhat overestimate global GFR in the setting of obstructive hydronephrosis [13]. Fluoroscopy Antegrade Pyelography There is limited evidence to support the use of fluoroscopic antegrade pyelography for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. Fluoroscopy Voiding Cystourethrography There is limited evidence to support the use of fluoroscopic voiding cystourethrography for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. MAG3 Renal Scan Although DRG is the de facto standard of care in diagnosis of renal obstruction [10] and can be used to determine whether obstructive uropathy is truly present in cases of incidentally noted hydronephrosis or in suspected obstruction of renal transplant [11], DRG is not preferred for initial imaging in pregnant patients. MRI Abdomen and Pelvis Without and With IV Contrast There is limited evidence to support the use of MRI abdomen and pelvis without and with IV contrast (separate from MRU) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause.

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Hydronephrosis on Prior Imaging Unknown Cause

Gadolinium contrast administration is avoided during pregnancy and should be considered only if the imaging is essential and cannot be delayed [42] or replaced by alternative imaging. MRI Abdomen and Pelvis Without IV Contrast Although there is limited evidence to support the use of MRI abdomen and pelvis without IV contrast (separate from MRU) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause, it may be useful in this setting in some clinical situations. MRU without IV contrast may provide additional information in this setting. MRI Abdomen Without and With IV Contrast There is limited evidence to support the use of MRI abdomen without and with IV contrast (separate from MRU) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. Gadolinium contrast administration is avoided during pregnancy and should be considered only if the imaging is essential and cannot be delayed [42] or replaced by alternative imaging. Hydronephrosis on Prior Imaging-Unknown Cause MRI Abdomen Without IV Contrast There is limited evidence to support the use of MRI abdomen without IV contrast (separate from MRU) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. MRU Without and With IV Contrast There is limited evidence to support the use of MRU without and with IV contrast for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. Gadolinium contrast administration is avoided during pregnancy and should be considered only if the imaging is essential and cannot be delayed [42] or replaced by alternative imaging. MRU Without IV Contrast Although there is limited evidence to support the use of MRU without IV contrast for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause, MRU without IV contrast is preferred over CTU in pregnant patients [15].

Hydronephrosis on Prior Imaging Unknown Cause. Gadolinium contrast administration is avoided during pregnancy and should be considered only if the imaging is essential and cannot be delayed [42] or replaced by alternative imaging. MRI Abdomen and Pelvis Without IV Contrast Although there is limited evidence to support the use of MRI abdomen and pelvis without IV contrast (separate from MRU) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause, it may be useful in this setting in some clinical situations. MRU without IV contrast may provide additional information in this setting. MRI Abdomen Without and With IV Contrast There is limited evidence to support the use of MRI abdomen without and with IV contrast (separate from MRU) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. Gadolinium contrast administration is avoided during pregnancy and should be considered only if the imaging is essential and cannot be delayed [42] or replaced by alternative imaging. Hydronephrosis on Prior Imaging-Unknown Cause MRI Abdomen Without IV Contrast There is limited evidence to support the use of MRI abdomen without IV contrast (separate from MRU) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. MRU Without and With IV Contrast There is limited evidence to support the use of MRU without and with IV contrast for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. Gadolinium contrast administration is avoided during pregnancy and should be considered only if the imaging is essential and cannot be delayed [42] or replaced by alternative imaging. MRU Without IV Contrast Although there is limited evidence to support the use of MRU without IV contrast for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause, MRU without IV contrast is preferred over CTU in pregnant patients [15].

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Hydronephrosis on Prior Imaging Unknown Cause

MRU without IV contrast may be useful in this setting in some clinical situations and can be combined with anatomical imaging to provide more information than anatomical imaging alone. Radiography Abdomen and Pelvis There is limited evidence to support the use of radiography of the abdomen and pelvis for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. Radiography Intravenous Urography There is limited evidence to support the use of radiography with IVU (also referred to as IVP) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. Historically, IVP was used to evaluate hydronephrosis, but this study is considered obsolete in many settings [6]. US Abdomen There is relatively limited evidence to support the use of US of the abdomen for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. It may be useful if there is clinical concern for specific causes identifiable by transabdominal US, although the gravid uterus may limit sonographic evaluation of abdominopelvic structures. US abdomen is a less comprehensive examination of the genitourinary system than MRU without IV contrast or US color Doppler kidneys and bladder retroperitoneal. Variant 5: Adult. Symptomatic hydronephrosis in a pregnant patient with unknown cause. Initial imaging. Please note that this variant describes initial imaging evaluation after the discovery, by imaging or otherwise, of symptomatic hydronephrosis in a pregnant patient with unknown cause. The choice of initial imaging in this situation is dependent on clinical context and on the information available from the means of hydronephrosis discovery (eg, CT, MR, US). CT Abdomen and Pelvis With IV Contrast There is limited evidence to support the use of CT abdomen and pelvis with IV contrast (separate from CTU) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause.

Hydronephrosis on Prior Imaging Unknown Cause. MRU without IV contrast may be useful in this setting in some clinical situations and can be combined with anatomical imaging to provide more information than anatomical imaging alone. Radiography Abdomen and Pelvis There is limited evidence to support the use of radiography of the abdomen and pelvis for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. Radiography Intravenous Urography There is limited evidence to support the use of radiography with IVU (also referred to as IVP) for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. Historically, IVP was used to evaluate hydronephrosis, but this study is considered obsolete in many settings [6]. US Abdomen There is relatively limited evidence to support the use of US of the abdomen for initial imaging of pregnant patients with asymptomatic hydronephrosis with unknown cause. It may be useful if there is clinical concern for specific causes identifiable by transabdominal US, although the gravid uterus may limit sonographic evaluation of abdominopelvic structures. US abdomen is a less comprehensive examination of the genitourinary system than MRU without IV contrast or US color Doppler kidneys and bladder retroperitoneal. Variant 5: Adult. Symptomatic hydronephrosis in a pregnant patient with unknown cause. Initial imaging. Please note that this variant describes initial imaging evaluation after the discovery, by imaging or otherwise, of symptomatic hydronephrosis in a pregnant patient with unknown cause. The choice of initial imaging in this situation is dependent on clinical context and on the information available from the means of hydronephrosis discovery (eg, CT, MR, US). CT Abdomen and Pelvis With IV Contrast There is limited evidence to support the use of CT abdomen and pelvis with IV contrast (separate from CTU) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause.

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Hydronephrosis on Prior Imaging Unknown Cause

CT should be reserved for problematic situations in which a diagnosis cannot be made on US or MRI [17]. When CT is required, a low- dose CT protocol should be used [6]. CT Abdomen and Pelvis Without and With IV Contrast There is limited evidence to support the use of CT abdomen and pelvis without and with IV contrast (separate from CTU) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. CT should be reserved for problematic situations in which a diagnosis cannot be made on US or MRI [17]. When CT is required, a low-dose CT protocol should be used [6]. Hydronephrosis on Prior Imaging-Unknown Cause CT Abdomen and Pelvis Without IV Contrast There is limited evidence to support the use of CT abdomen and pelvis without IV contrast (separate from CTU) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. CT should be reserved for problematic situations in which a diagnosis cannot be made on US or MRI [17]. When CT is required, a low-dose CT protocol should be used [6]. CT Abdomen With IV Contrast There is limited evidence to support the use of CT abdomen with IV contrast (separate from CTU) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. CT Abdomen Without and With IV Contrast There is limited evidence to support the use of CT abdomen without and with IV contrast (separate from CTU) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. CT Abdomen Without IV Contrast There is limited evidence to support the use of CT abdomen without IV contrast (separate from CTU) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. CTU Without and With IV Contrast There is limited evidence to support the use of CTU without and with IV contrast for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause.

Hydronephrosis on Prior Imaging Unknown Cause. CT should be reserved for problematic situations in which a diagnosis cannot be made on US or MRI [17]. When CT is required, a low- dose CT protocol should be used [6]. CT Abdomen and Pelvis Without and With IV Contrast There is limited evidence to support the use of CT abdomen and pelvis without and with IV contrast (separate from CTU) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. CT should be reserved for problematic situations in which a diagnosis cannot be made on US or MRI [17]. When CT is required, a low-dose CT protocol should be used [6]. Hydronephrosis on Prior Imaging-Unknown Cause CT Abdomen and Pelvis Without IV Contrast There is limited evidence to support the use of CT abdomen and pelvis without IV contrast (separate from CTU) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. CT should be reserved for problematic situations in which a diagnosis cannot be made on US or MRI [17]. When CT is required, a low-dose CT protocol should be used [6]. CT Abdomen With IV Contrast There is limited evidence to support the use of CT abdomen with IV contrast (separate from CTU) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. CT Abdomen Without and With IV Contrast There is limited evidence to support the use of CT abdomen without and with IV contrast (separate from CTU) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. CT Abdomen Without IV Contrast There is limited evidence to support the use of CT abdomen without IV contrast (separate from CTU) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. CTU Without and With IV Contrast There is limited evidence to support the use of CTU without and with IV contrast for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause.

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Hydronephrosis on Prior Imaging Unknown Cause

CT should be reserved for problematic situations in which a diagnosis cannot be made on US or MRI [17]. When CT is required, a low-dose CT protocol should be used [6]. DTPA Renal Scan Although DRG is the de facto standard of care in diagnosis of renal obstruction [10] and can be used to determine whether obstructive uropathy is truly present in cases of incidentally noted hydronephrosis or in suspected obstruction of renal transplant [11], DRG is not preferred for initial imaging in pregnant patients. Note that use of DTPA for diuretic renography may result in an equivocal or false-positive diuretic study compared with MAG3, particularly in patients with reduced function, and is not favored [11,12]. DRG with DTPA can also be used to estimate single-kidney GFR but may somewhat overestimate global GFR in the setting of obstructive hydronephrosis [13]. Fluoroscopy Antegrade Pyelography There is limited evidence to support the use of fluoroscopic antegrade pyelography for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. Fluoroscopy Voiding Cystourethrography There is limited evidence to support the use of fluoroscopic voiding cystourethrography for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. MAG3 Renal Scan Although DRG is the de facto standard of care in diagnosis of renal obstruction [10] and can be used to determine whether obstructive uropathy is truly present in cases of incidentally noted hydronephrosis or in suspected obstruction of renal transplant [11], DRG is not preferred for initial imaging in pregnant patients. MRI Abdomen and Pelvis Without and With IV Contrast There is limited evidence to support the use of MRI abdomen and pelvis without and with IV contrast (separate from MRU) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause.

Hydronephrosis on Prior Imaging Unknown Cause. CT should be reserved for problematic situations in which a diagnosis cannot be made on US or MRI [17]. When CT is required, a low-dose CT protocol should be used [6]. DTPA Renal Scan Although DRG is the de facto standard of care in diagnosis of renal obstruction [10] and can be used to determine whether obstructive uropathy is truly present in cases of incidentally noted hydronephrosis or in suspected obstruction of renal transplant [11], DRG is not preferred for initial imaging in pregnant patients. Note that use of DTPA for diuretic renography may result in an equivocal or false-positive diuretic study compared with MAG3, particularly in patients with reduced function, and is not favored [11,12]. DRG with DTPA can also be used to estimate single-kidney GFR but may somewhat overestimate global GFR in the setting of obstructive hydronephrosis [13]. Fluoroscopy Antegrade Pyelography There is limited evidence to support the use of fluoroscopic antegrade pyelography for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. Fluoroscopy Voiding Cystourethrography There is limited evidence to support the use of fluoroscopic voiding cystourethrography for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. MAG3 Renal Scan Although DRG is the de facto standard of care in diagnosis of renal obstruction [10] and can be used to determine whether obstructive uropathy is truly present in cases of incidentally noted hydronephrosis or in suspected obstruction of renal transplant [11], DRG is not preferred for initial imaging in pregnant patients. MRI Abdomen and Pelvis Without and With IV Contrast There is limited evidence to support the use of MRI abdomen and pelvis without and with IV contrast (separate from MRU) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause.

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Hydronephrosis on Prior Imaging Unknown Cause

Gadolinium contrast administration is avoided during pregnancy and should be considered only if the imaging is essential and cannot be delayed [42] or replaced by alternative imaging. MRI Abdomen and Pelvis Without IV Contrast There is limited evidence to support the use of MRI abdomen and pelvis without IV contrast (separate from MRU) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause, although MRI can play a useful adjunct role in pregnant patients with renal colic and equivocal or nondiagnostic initial US findings [17]. Hydronephrosis on Prior Imaging-Unknown Cause MRI Abdomen Without and With IV Contrast There is limited evidence to support the use of MRI abdomen without and with IV contrast (separate from MRU) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. Gadolinium contrast administration is avoided during pregnancy and should be considered only if the imaging is essential and cannot be delayed [42] or replaced by alternative imaging. MRI Abdomen Without IV Contrast There is limited evidence to support the use of MRI abdomen without IV contrast (separate from MRU) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause, although MRI can play a useful adjunct role in pregnant patients with renal colic and equivocal or nondiagnostic initial US findings [17]. MRU Without and With IV Contrast There is limited evidence to support the use of MRU without and with IV contrast for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. Gadolinium contrast administration is avoided during pregnancy and should be considered only if the imaging is essential and cannot be delayed [42] or replaced by alternative imaging. MRU Without IV Contrast There is some evidence for use of MRU without IV contrast for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause.

Hydronephrosis on Prior Imaging Unknown Cause. Gadolinium contrast administration is avoided during pregnancy and should be considered only if the imaging is essential and cannot be delayed [42] or replaced by alternative imaging. MRI Abdomen and Pelvis Without IV Contrast There is limited evidence to support the use of MRI abdomen and pelvis without IV contrast (separate from MRU) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause, although MRI can play a useful adjunct role in pregnant patients with renal colic and equivocal or nondiagnostic initial US findings [17]. Hydronephrosis on Prior Imaging-Unknown Cause MRI Abdomen Without and With IV Contrast There is limited evidence to support the use of MRI abdomen without and with IV contrast (separate from MRU) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. Gadolinium contrast administration is avoided during pregnancy and should be considered only if the imaging is essential and cannot be delayed [42] or replaced by alternative imaging. MRI Abdomen Without IV Contrast There is limited evidence to support the use of MRI abdomen without IV contrast (separate from MRU) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause, although MRI can play a useful adjunct role in pregnant patients with renal colic and equivocal or nondiagnostic initial US findings [17]. MRU Without and With IV Contrast There is limited evidence to support the use of MRU without and with IV contrast for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. Gadolinium contrast administration is avoided during pregnancy and should be considered only if the imaging is essential and cannot be delayed [42] or replaced by alternative imaging. MRU Without IV Contrast There is some evidence for use of MRU without IV contrast for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause.

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Hydronephrosis on Prior Imaging Unknown Cause

Although it can be performed independently, MRU can also be performed at the time of structural MRI. In a study of 24 pregnant patients with symptomatic hydronephrosis, MRU was noted to show different appearances in physiologic hydronephrosis and pathologic obstruction [44]. Multiple authors suggest that noncontrast MRU should be considered after an equivocal or nondiagnostic US in symptomatic pregnant patients with suspected urolithiasis [6,17]. In a prospective study of 55 nonpregnant patients with hydronephrosis detected on US for urologic symptoms, excluding patients with abnormal renal function given contraindication for IVU, Muthusami et al [30] compared static heavily T2-weighted MRU to reference IVU and determined that MRU had high sensitivity and specificity for detecting (95% and 100%, respectively) and grading (Spearman correlation coefficient 0.92) hydronephrosis, as well as identifying the location of obstruction (90% and 99%, respectively) if present. The authors conclude that static MRU can replace IVU when the latter is contraindicated or technically difficult. The authors note that MRU sensitivity for hydronephrosis grading increased with grade of obstruction. Radiography Abdomen and Pelvis There is limited evidence to support the use of radiography of the abdomen and pelvis for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. Radiography Intravenous Urography There is limited evidence to support the use of radiography with IVU (also referred to as IVP) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. Historically, IVP was used to evaluate symptomatic pregnant patients suspected to have renal obstruction; however, due to radiation exposure, IV contrast administration and increased usage of cross-sectional imaging, this study is considered obsolete in many settings [6].

Hydronephrosis on Prior Imaging Unknown Cause. Although it can be performed independently, MRU can also be performed at the time of structural MRI. In a study of 24 pregnant patients with symptomatic hydronephrosis, MRU was noted to show different appearances in physiologic hydronephrosis and pathologic obstruction [44]. Multiple authors suggest that noncontrast MRU should be considered after an equivocal or nondiagnostic US in symptomatic pregnant patients with suspected urolithiasis [6,17]. In a prospective study of 55 nonpregnant patients with hydronephrosis detected on US for urologic symptoms, excluding patients with abnormal renal function given contraindication for IVU, Muthusami et al [30] compared static heavily T2-weighted MRU to reference IVU and determined that MRU had high sensitivity and specificity for detecting (95% and 100%, respectively) and grading (Spearman correlation coefficient 0.92) hydronephrosis, as well as identifying the location of obstruction (90% and 99%, respectively) if present. The authors conclude that static MRU can replace IVU when the latter is contraindicated or technically difficult. The authors note that MRU sensitivity for hydronephrosis grading increased with grade of obstruction. Radiography Abdomen and Pelvis There is limited evidence to support the use of radiography of the abdomen and pelvis for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. Radiography Intravenous Urography There is limited evidence to support the use of radiography with IVU (also referred to as IVP) for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. Historically, IVP was used to evaluate symptomatic pregnant patients suspected to have renal obstruction; however, due to radiation exposure, IV contrast administration and increased usage of cross-sectional imaging, this study is considered obsolete in many settings [6].

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Hydronephrosis on Prior Imaging Unknown Cause

US Abdomen There is relatively limited evidence to support the use of US of the abdomen for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. It may be useful if there is clinical concern for specific causes identifiable by transabdominal US, although the gravid uterus may limit sonographic evaluation of abdominopelvic structures. US abdomen is a less comprehensive examination of the genitourinary system than MRU without IV contrast or US color Doppler kidneys and bladder retroperitoneal. US Color Doppler Kidneys and Bladder Retroperitoneal US is the first-line study for diagnosis of maternal hydronephrosis or renal anatomic abnormalities [5,17,43]. In the pregnant patient with known, symptomatic hydronephrosis, specific findings on US including anteroposterior 21 Hydronephrosis on Prior Imaging-Unknown Cause diameter of the renal pelvis and renal RI can help differentiate benign pregnancy-related hydronephrosis and pathologic obstruction and can help predict the need for intervention. In a prospective single-center study of 1,026 pregnant patients including 295 with hydronephrosis, Bayraktar et al [5] reported a correlation between anteroposterior diameter of the renal pelvis on US and requirement for intervention for symptomatic patients. Ercil et al [9] report the same finding in a retrospective single-center series of 246 pregnant patients with symptomatic hydronephrosis, noting that a diameter above 21 mm on the right had a sensitivity of 91% and a specificity of 84% for predicting intervention, and a diameter above 25 mm on the left had a sensitivity and specificity of 100%. Demir et al [45] reported in a study of 227 pregnant women with symptomatic hydronephrosis that intervention was found to be necessary with renal pelvis anteroposterior diameter >16.5 mm in the first two trimesters and >27.5 mm in the third trimester.

Hydronephrosis on Prior Imaging Unknown Cause. US Abdomen There is relatively limited evidence to support the use of US of the abdomen for initial imaging of pregnant patients with symptomatic hydronephrosis with unknown cause. It may be useful if there is clinical concern for specific causes identifiable by transabdominal US, although the gravid uterus may limit sonographic evaluation of abdominopelvic structures. US abdomen is a less comprehensive examination of the genitourinary system than MRU without IV contrast or US color Doppler kidneys and bladder retroperitoneal. US Color Doppler Kidneys and Bladder Retroperitoneal US is the first-line study for diagnosis of maternal hydronephrosis or renal anatomic abnormalities [5,17,43]. In the pregnant patient with known, symptomatic hydronephrosis, specific findings on US including anteroposterior 21 Hydronephrosis on Prior Imaging-Unknown Cause diameter of the renal pelvis and renal RI can help differentiate benign pregnancy-related hydronephrosis and pathologic obstruction and can help predict the need for intervention. In a prospective single-center study of 1,026 pregnant patients including 295 with hydronephrosis, Bayraktar et al [5] reported a correlation between anteroposterior diameter of the renal pelvis on US and requirement for intervention for symptomatic patients. Ercil et al [9] report the same finding in a retrospective single-center series of 246 pregnant patients with symptomatic hydronephrosis, noting that a diameter above 21 mm on the right had a sensitivity of 91% and a specificity of 84% for predicting intervention, and a diameter above 25 mm on the left had a sensitivity and specificity of 100%. Demir et al [45] reported in a study of 227 pregnant women with symptomatic hydronephrosis that intervention was found to be necessary with renal pelvis anteroposterior diameter >16.5 mm in the first two trimesters and >27.5 mm in the third trimester.

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acrac_69456_0

Noninvasive Clinical Staging of Primary Lung Cancer PCAs

Introduction/Background Lung cancer is the leading cause of cancer-related deaths in both men and women. While the incidence of the disease for men in the United States has been steadily decreasing since the 1970s, the incidence for women in the United States increased after 1975 before leveling in the 2000s [1]. The major risk factor for lung cancer is personal tobacco smoking, particularly for small-cell lung cancer (SCLC) and squamous-cell lung cancers, but other significant risk factors include exposure to second-hand smoke, environmental radon, occupational exposures, and air pollution. Education and socioeconomic status affect both incidence and outcomes, with a disproportionate amount of the disease burden seen in the poor and poorly educated. The economic cost of caring for lung cancer patients in the United States is over $12 billion per year. Mortality cost from lost productivity also numbers in the billions of dollars [2]. aThe University of Texas MD Anderson Cancer Center, Houston, Texas. bPanel Chair, University of Chicago, Chicago, Illinois. cMassachusetts General Hospital and Harvard Medical School, Boston, Massachusetts. dStanford University Medical Center, Stanford, California; The Society of Thoracic Surgeons. eThe University of Texas MD Anderson Cancer Center, Houston, Texas. fUniversity of Southern California, Los Angeles, California. gUniversity of Kentucky, Lexington, Kentucky. hMayo Clinic, Jacksonville, Florida. iHenry Ford Cancer Institute, Detroit, Michigan. jDuke University School of Medicine, Durham, North Carolina; The Society of Thoracic Surgeons. kUniversity of Kansas Medical Center, Kansas City, Kansas. lUniversity of California San Francisco, San Francisco, California. mSpecialty Chair, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.

Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Introduction/Background Lung cancer is the leading cause of cancer-related deaths in both men and women. While the incidence of the disease for men in the United States has been steadily decreasing since the 1970s, the incidence for women in the United States increased after 1975 before leveling in the 2000s [1]. The major risk factor for lung cancer is personal tobacco smoking, particularly for small-cell lung cancer (SCLC) and squamous-cell lung cancers, but other significant risk factors include exposure to second-hand smoke, environmental radon, occupational exposures, and air pollution. Education and socioeconomic status affect both incidence and outcomes, with a disproportionate amount of the disease burden seen in the poor and poorly educated. The economic cost of caring for lung cancer patients in the United States is over $12 billion per year. Mortality cost from lost productivity also numbers in the billions of dollars [2]. aThe University of Texas MD Anderson Cancer Center, Houston, Texas. bPanel Chair, University of Chicago, Chicago, Illinois. cMassachusetts General Hospital and Harvard Medical School, Boston, Massachusetts. dStanford University Medical Center, Stanford, California; The Society of Thoracic Surgeons. eThe University of Texas MD Anderson Cancer Center, Houston, Texas. fUniversity of Southern California, Los Angeles, California. gUniversity of Kentucky, Lexington, Kentucky. hMayo Clinic, Jacksonville, Florida. iHenry Ford Cancer Institute, Detroit, Michigan. jDuke University School of Medicine, Durham, North Carolina; The Society of Thoracic Surgeons. kUniversity of Kansas Medical Center, Kansas City, Kansas. lUniversity of California San Francisco, San Francisco, California. mSpecialty Chair, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.

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acrac_69456_1

Noninvasive Clinical Staging of Primary Lung Cancer PCAs

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] N Descriptor The eighth edition makes no changes from the previous edition with regard to metastatic nodal disease. The N stage is based on location of metastatic nodes. Increasing number of involved nodal stations negatively affects prognosis [5]. A lymph node size threshold of >10 mm in axial short axis diameter is considered abnormal. The prevalence of metastatic lung cancer in thoracic lymph nodes is 30% for nodes that are 10 to 15 mm in short axis diameter and 67% for nodes >15 mm [7]. Axillary lymph node metastasis occurs in 0.75% of lung cancers [8]. It is not included in the N descriptor but is considered metastatic M1 disease. Nx indicates that lymph nodes cannot be assessed [5]. N0 is consistent with lack of regional node involvement [5]. N1 includes ipsilateral peribronchial, hilar or intrapulmonary lymph node(s) [5]. N2 describes ipsilateral mediastinal or subcarinal lymph node(s) [5]. N3 includes contralateral mediastinal or hilar lymph node(s) and any supraclavicular or scalene node on either side [5]. M Descriptor The presence of metastatic lung cancer lesions constitutes stage IV disease. Many patients with NSCLC present with metastatic disease [9], and the treatment of stage IV cancers depends on the location and number of lesions. M0 disease is consistent with no distant metastases [5]. The M1 classification is subdivided into three categories: M1a includes satellite nodule(s) in the contralateral lung and cytology proven malignant pleural or pericardial effusion [5]. M1b indicates a single extrathoracic metastasis.

Noninvasive Clinical Staging of Primary Lung Cancer PCAs. 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] N Descriptor The eighth edition makes no changes from the previous edition with regard to metastatic nodal disease. The N stage is based on location of metastatic nodes. Increasing number of involved nodal stations negatively affects prognosis [5]. A lymph node size threshold of >10 mm in axial short axis diameter is considered abnormal. The prevalence of metastatic lung cancer in thoracic lymph nodes is 30% for nodes that are 10 to 15 mm in short axis diameter and 67% for nodes >15 mm [7]. Axillary lymph node metastasis occurs in 0.75% of lung cancers [8]. It is not included in the N descriptor but is considered metastatic M1 disease. Nx indicates that lymph nodes cannot be assessed [5]. N0 is consistent with lack of regional node involvement [5]. N1 includes ipsilateral peribronchial, hilar or intrapulmonary lymph node(s) [5]. N2 describes ipsilateral mediastinal or subcarinal lymph node(s) [5]. N3 includes contralateral mediastinal or hilar lymph node(s) and any supraclavicular or scalene node on either side [5]. M Descriptor The presence of metastatic lung cancer lesions constitutes stage IV disease. Many patients with NSCLC present with metastatic disease [9], and the treatment of stage IV cancers depends on the location and number of lesions. M0 disease is consistent with no distant metastases [5]. The M1 classification is subdivided into three categories: M1a includes satellite nodule(s) in the contralateral lung and cytology proven malignant pleural or pericardial effusion [5]. M1b indicates a single extrathoracic metastasis.

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Noninvasive Clinical Staging of Primary Lung Cancer PCAs

This category also includes metastasis in a single nonregional lymph node, considered nodes not in the N descriptor, such as enlarged axillary, internal mammary, and/or abdominal lymph node [5,6]. M1c indicates multiple extrathoracic metastases in one or more organs [5]. Stage Groups for NSCLC Stage groupings have been revised according to statistically significant differences in survival among tumors in the database. The eighth edition includes new differentiation among stage IA tumors based on size of the tumor and a new stage IIIC category for T3 and T4 tumors with N3M0 disease [6]. Classification of mucinous adenocarcinomas is also addressed. The T descriptor is based on size if confined to a single lobe. The tumor is designated as T3 if size cannot be determined but remains in a single lobe. Involvement of multiple ipsilateral lobes is T4 disease. Bilateral lesions are considered M1a [5,10]. CT Chest For patients with known or suspected NSCLC, a chest CT with intravenous (IV) contrast is recommended. A chest CT without IV contrast may also be obtained. Noninvasive Clinical Staging of Primary Lung Cancer Chest CT is the modality of choice for initial evaluation of the T descriptor, specifically the size and location of the primary tumor. Diagnosis of chest wall or mediastinal invasion on CT can be equivocal in cases of minimal invasion. Radiologic imaging cannot consistently detect visceral pleural invasion. Chest CT with IV contrast can aid in the identification of mediastinal or chest wall invasion by tumor, evaluation of hilar lymph nodes, distinction of central obstructing tumor from surrounding atelectasis, and assessment for liver metastases [11,12]. Chest CT without IV contrast is often better able to characterize adrenal nodules than chest CT with contrast, but the benefit of a noncontrast chest CT for this purpose may be obviated by performance of PET or PET/CT.

Noninvasive Clinical Staging of Primary Lung Cancer PCAs. This category also includes metastasis in a single nonregional lymph node, considered nodes not in the N descriptor, such as enlarged axillary, internal mammary, and/or abdominal lymph node [5,6]. M1c indicates multiple extrathoracic metastases in one or more organs [5]. Stage Groups for NSCLC Stage groupings have been revised according to statistically significant differences in survival among tumors in the database. The eighth edition includes new differentiation among stage IA tumors based on size of the tumor and a new stage IIIC category for T3 and T4 tumors with N3M0 disease [6]. Classification of mucinous adenocarcinomas is also addressed. The T descriptor is based on size if confined to a single lobe. The tumor is designated as T3 if size cannot be determined but remains in a single lobe. Involvement of multiple ipsilateral lobes is T4 disease. Bilateral lesions are considered M1a [5,10]. CT Chest For patients with known or suspected NSCLC, a chest CT with intravenous (IV) contrast is recommended. A chest CT without IV contrast may also be obtained. Noninvasive Clinical Staging of Primary Lung Cancer Chest CT is the modality of choice for initial evaluation of the T descriptor, specifically the size and location of the primary tumor. Diagnosis of chest wall or mediastinal invasion on CT can be equivocal in cases of minimal invasion. Radiologic imaging cannot consistently detect visceral pleural invasion. Chest CT with IV contrast can aid in the identification of mediastinal or chest wall invasion by tumor, evaluation of hilar lymph nodes, distinction of central obstructing tumor from surrounding atelectasis, and assessment for liver metastases [11,12]. Chest CT without IV contrast is often better able to characterize adrenal nodules than chest CT with contrast, but the benefit of a noncontrast chest CT for this purpose may be obviated by performance of PET or PET/CT.

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Noninvasive Clinical Staging of Primary Lung Cancer PCAs

Accurate N staging of the mediastinum is important in distinguishing resectable from unresectable disease. CT staging of nodal disease in the mediastinum is inadequate because of its low sensitivity and specificity of anatomic size criteria [11]. A meta-analysis of over 7,000 patients found that the prevalence of mediastinal lymph node metastasis was 30%. However, the median sensitivity of contrast-enhanced CT was 55%, and median specificity was 81% for mediastinal nodal disease using the >10-mm short axis diameter criteria [11]. Findings on chest CT of enlarged mediastinal nodes aids in guiding biopsy, as invasive staging of the mediastinum is recommended over imaging alone [11]. The distribution of mediastinal lymph node metastases is influenced by the location of the primary tumor. Right upper lobe tumors drain to the right paratracheal nodes (2R and 4R), while right middle and lower lobe tumors most frequently drain to the lower right paratracheal and subcarinal nodes (4R and 7R). Nodal metastases for the left upper lobe are most often seen in the aorticopulmonary window and prevascular nodes (5L and 6L). Left lower lobe tumors drain to the prevascular and subcarinal nodes (6L and 7L) [13]. Tumors in the lower lobe superior segments frequently have upper mediastinal lymph node involvement (64%) compared with basal segment tumors [14]. Chest CT is adequate for the identification of contralateral lung nodules constituting M1a disease. It also identifies pleural or pericardial effusions that may need cytological confirmation if pleural or pericardial nodules are not visible. Extrathoracic M1b metastases of the adrenal glands and bone structures may be seen on a chest CT. However, adrenal nodules may not be definitively characterized by CT if IV contrast is used or if intracytoplasmic lipid content is low, which occurs in approximately one-third of adrenal adenomas.

Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Accurate N staging of the mediastinum is important in distinguishing resectable from unresectable disease. CT staging of nodal disease in the mediastinum is inadequate because of its low sensitivity and specificity of anatomic size criteria [11]. A meta-analysis of over 7,000 patients found that the prevalence of mediastinal lymph node metastasis was 30%. However, the median sensitivity of contrast-enhanced CT was 55%, and median specificity was 81% for mediastinal nodal disease using the >10-mm short axis diameter criteria [11]. Findings on chest CT of enlarged mediastinal nodes aids in guiding biopsy, as invasive staging of the mediastinum is recommended over imaging alone [11]. The distribution of mediastinal lymph node metastases is influenced by the location of the primary tumor. Right upper lobe tumors drain to the right paratracheal nodes (2R and 4R), while right middle and lower lobe tumors most frequently drain to the lower right paratracheal and subcarinal nodes (4R and 7R). Nodal metastases for the left upper lobe are most often seen in the aorticopulmonary window and prevascular nodes (5L and 6L). Left lower lobe tumors drain to the prevascular and subcarinal nodes (6L and 7L) [13]. Tumors in the lower lobe superior segments frequently have upper mediastinal lymph node involvement (64%) compared with basal segment tumors [14]. Chest CT is adequate for the identification of contralateral lung nodules constituting M1a disease. It also identifies pleural or pericardial effusions that may need cytological confirmation if pleural or pericardial nodules are not visible. Extrathoracic M1b metastases of the adrenal glands and bone structures may be seen on a chest CT. However, adrenal nodules may not be definitively characterized by CT if IV contrast is used or if intracytoplasmic lipid content is low, which occurs in approximately one-third of adrenal adenomas.

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Noninvasive Clinical Staging of Primary Lung Cancer PCAs

Techniques for further evaluation include PET using the tracer fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG) with CT, CT adrenal washout protocol, and MR chemical shift of in- and out-of-phase imaging [15]. Liver metastases may be seen if they occur within the included segments on chest CT and are better identified on contrast-enhanced studies, particularly if lesions are small. FDG-PET/CT Skull Base to Mid-Thigh FDG-PET/CT is recommended to evaluate for extrathoracic metastases in patients with NSCLC. It is not required for patients with stage 0 adenocarcinoma in situ with an otherwise normal chest CT examination. FDG-PET is reported to change management in 14% to 26% of NSCLC patients [16-18]. FDG-PET imaging is superior to CT in detection of nodal and distant metastases [19]. FDG-PET may upstage NSCLC by identifying metastases that were occult on CT imaging or downstage the malignancy by demonstrating lack of glucose metabolism in a suspected lesion [20]. Integrated FDG-PET/CT is more accurate for staging of the N and M descriptors than independent FDG-PET or diagnostic CT [21]. FDG-PET or PET/CT is reported to reduce futile thoracotomies by 20% and 17%, respectively [19,22]. FDG-PET has sensitivity of 94% and specificity of 82% for characterization of adrenal nodules and is superior to CT alone. Lack of FDG uptake in an adrenal nodule is considered conclusive for benign adrenal adenoma and obviates further workup [31]. Patients with an FDG-avid adrenal nodule as the only site of potential metastatic disease require biopsy confirmation [11]. The sensitivity, specificity, accuracy, and negative predictive value of FDG-PET for bone metastases are >90%, which is superior to bone scintigraphy [32-35]. Liver metastases may be present in up to 3% to 4% of asymptomatic NSCLC patients at the time of presentation [36].

Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Techniques for further evaluation include PET using the tracer fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG) with CT, CT adrenal washout protocol, and MR chemical shift of in- and out-of-phase imaging [15]. Liver metastases may be seen if they occur within the included segments on chest CT and are better identified on contrast-enhanced studies, particularly if lesions are small. FDG-PET/CT Skull Base to Mid-Thigh FDG-PET/CT is recommended to evaluate for extrathoracic metastases in patients with NSCLC. It is not required for patients with stage 0 adenocarcinoma in situ with an otherwise normal chest CT examination. FDG-PET is reported to change management in 14% to 26% of NSCLC patients [16-18]. FDG-PET imaging is superior to CT in detection of nodal and distant metastases [19]. FDG-PET may upstage NSCLC by identifying metastases that were occult on CT imaging or downstage the malignancy by demonstrating lack of glucose metabolism in a suspected lesion [20]. Integrated FDG-PET/CT is more accurate for staging of the N and M descriptors than independent FDG-PET or diagnostic CT [21]. FDG-PET or PET/CT is reported to reduce futile thoracotomies by 20% and 17%, respectively [19,22]. FDG-PET has sensitivity of 94% and specificity of 82% for characterization of adrenal nodules and is superior to CT alone. Lack of FDG uptake in an adrenal nodule is considered conclusive for benign adrenal adenoma and obviates further workup [31]. Patients with an FDG-avid adrenal nodule as the only site of potential metastatic disease require biopsy confirmation [11]. The sensitivity, specificity, accuracy, and negative predictive value of FDG-PET for bone metastases are >90%, which is superior to bone scintigraphy [32-35]. Liver metastases may be present in up to 3% to 4% of asymptomatic NSCLC patients at the time of presentation [36].

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Noninvasive Clinical Staging of Primary Lung Cancer PCAs

Although there is heterogeneous physiologic FDG activity in the liver, the accuracy of FDG-PET and PET/CT for liver metastases is reported to be 92% to 100% [37]. When findings are discordant or indeterminate, MRI and/or biopsy are appropriate strategies to evaluate liver lesions. FDG-PET cannot be used for tumor measurement purposes, but integrated PET/CT allows anatomic measurement on the CT portion of the examination for the T descriptor. CT Abdomen and Pelvis CT abdomen and pelvis with oral and IV contrast may be used as an alternate imaging modality to evaluate for extrathoracic metastasis in lung cancer patients being considered for curative therapy if FDG-PET or PET/CT is not performed [11]. Acquisitions of arterial and portal venous phase sequences are advised. CT abdomen and pelvis with oral and IV contrast is recommended in NSCLC patients with abnormal clinical evaluation, including signs or symptoms referable to the abdomen and pelvis and no suspicious extrathoracic findings on chest CT [11]. All NSCLC with locally advanced stage III or stage IV disease should undergo extrathoracic imaging with either CT abdomen and pelvis or FDG-PET or PET/CT because of the likelihood of occult extrathoracic metastatic disease in up to 37% of cases [11]. Bone Scan Whole Body Technetium-99m (Tc-99m) bone scintigraphy may be used as an alternate imaging modality to evaluate for bone metastasis in NSCLC patients if FDG-PET or PET/CT is not performed or is equivocal for osseous findings. Bone scintigraphy was historically used to detect osseous metastatic disease in lung cancer patients. A recent meta-analysis found it has a pooled sensitivity of 91.8%; however, the pooled specificity for bone metastases from lung cancer on bone scintigraphy was 68.8%, which is primarily due to confounders such as degenerative disease, inflammation, and prior trauma [38].

Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Although there is heterogeneous physiologic FDG activity in the liver, the accuracy of FDG-PET and PET/CT for liver metastases is reported to be 92% to 100% [37]. When findings are discordant or indeterminate, MRI and/or biopsy are appropriate strategies to evaluate liver lesions. FDG-PET cannot be used for tumor measurement purposes, but integrated PET/CT allows anatomic measurement on the CT portion of the examination for the T descriptor. CT Abdomen and Pelvis CT abdomen and pelvis with oral and IV contrast may be used as an alternate imaging modality to evaluate for extrathoracic metastasis in lung cancer patients being considered for curative therapy if FDG-PET or PET/CT is not performed [11]. Acquisitions of arterial and portal venous phase sequences are advised. CT abdomen and pelvis with oral and IV contrast is recommended in NSCLC patients with abnormal clinical evaluation, including signs or symptoms referable to the abdomen and pelvis and no suspicious extrathoracic findings on chest CT [11]. All NSCLC with locally advanced stage III or stage IV disease should undergo extrathoracic imaging with either CT abdomen and pelvis or FDG-PET or PET/CT because of the likelihood of occult extrathoracic metastatic disease in up to 37% of cases [11]. Bone Scan Whole Body Technetium-99m (Tc-99m) bone scintigraphy may be used as an alternate imaging modality to evaluate for bone metastasis in NSCLC patients if FDG-PET or PET/CT is not performed or is equivocal for osseous findings. Bone scintigraphy was historically used to detect osseous metastatic disease in lung cancer patients. A recent meta-analysis found it has a pooled sensitivity of 91.8%; however, the pooled specificity for bone metastases from lung cancer on bone scintigraphy was 68.8%, which is primarily due to confounders such as degenerative disease, inflammation, and prior trauma [38].

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Noninvasive Clinical Staging of Primary Lung Cancer PCAs

FDG-PET and PET/CT have significantly higher sensitivity, specificity, accuracy, and negative predictive value than bone scan [34,35]. MRI Brain MRI brain without and with IV contrast is recommended in any patient with clinical stage II, III, or IV NSCLC, even in the absence of neurologic symptoms [39]. MRI brain without and with IV contrast is optional in patients with clinical stage IB NSCLC without neurologic symptoms [39]. MRI brain without and with IV contrast is recommended in all NSCLC patients with neurologic symptoms, regardless of stage. MRI brain is the preferred imaging modality for evaluation of intracranial metastases, as it is more sensitive for small brain lesions than CT [11,40]. In a meta-analysis of NSCLC patients without neurologic symptoms, the median prevalence of brain lesions was 3% [11]. However, a small study found that 22% of asymptomatic patients with tumor size >3 cm had brain metastases [41]. Any NSCLC patient with neurologic symptoms should be screened for intracranial metastasis [11]. Brain metastases have been associated with adenocarcinoma NSCLC and N2 disease [11,42]. CT Head CT head with IV contrast can be used as an alternate imaging modality in stage III or IV NSCLC patients and NSCLC patients with neurologic symptoms if MRI head is not obtained. Dual-phase imaging may be useful in this clinical setting. CT scanning of the brain is an appropriate method of evaluating for brain metastases in patients with NSCLC [11]. Although MRI has greater sensitivity than CT, the identification of more and smaller brain lesions on MRI compared with CT has not been associated with better survival or the identification of more patients with brain lesions [43,44]. Noninvasive Clinical Staging of Primary Lung Cancer MRI Chest MRI chest without and with IV contrast may be indicated in specific clinical circumstances in NSCLC patients with equivocal findings on CT chest.

Noninvasive Clinical Staging of Primary Lung Cancer PCAs. FDG-PET and PET/CT have significantly higher sensitivity, specificity, accuracy, and negative predictive value than bone scan [34,35]. MRI Brain MRI brain without and with IV contrast is recommended in any patient with clinical stage II, III, or IV NSCLC, even in the absence of neurologic symptoms [39]. MRI brain without and with IV contrast is optional in patients with clinical stage IB NSCLC without neurologic symptoms [39]. MRI brain without and with IV contrast is recommended in all NSCLC patients with neurologic symptoms, regardless of stage. MRI brain is the preferred imaging modality for evaluation of intracranial metastases, as it is more sensitive for small brain lesions than CT [11,40]. In a meta-analysis of NSCLC patients without neurologic symptoms, the median prevalence of brain lesions was 3% [11]. However, a small study found that 22% of asymptomatic patients with tumor size >3 cm had brain metastases [41]. Any NSCLC patient with neurologic symptoms should be screened for intracranial metastasis [11]. Brain metastases have been associated with adenocarcinoma NSCLC and N2 disease [11,42]. CT Head CT head with IV contrast can be used as an alternate imaging modality in stage III or IV NSCLC patients and NSCLC patients with neurologic symptoms if MRI head is not obtained. Dual-phase imaging may be useful in this clinical setting. CT scanning of the brain is an appropriate method of evaluating for brain metastases in patients with NSCLC [11]. Although MRI has greater sensitivity than CT, the identification of more and smaller brain lesions on MRI compared with CT has not been associated with better survival or the identification of more patients with brain lesions [43,44]. Noninvasive Clinical Staging of Primary Lung Cancer MRI Chest MRI chest without and with IV contrast may be indicated in specific clinical circumstances in NSCLC patients with equivocal findings on CT chest.

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Noninvasive Clinical Staging of Primary Lung Cancer PCAs

Focused MRI of the chest may be useful in assessment of chest wall or spinal invasion and tumor involvement of mediastinal structures, including the heart, great vessels, and pericardium. MRI assessment of superior sulcus tumors for brachial plexus involvement is standard of care [45]. MRI is superior to CT for detecting involvement of the neural foramina and spinal canal. Dynamic cine MRI with free breathing can determine lack of invasion if there is respiration-coordinated sliding between the tumor and mediastinum or chest wall, and it can also evaluate for phrenic nerve involvement by lymphadenopathy or the primary tumor. Conversely, restriction of tumor motion is not conclusive since inflammation or adhesion may also affect mobility [46,47]. MRI is also capable of distinguishing an obstructing tumor from postobstructive atelectasis. Diffusion- weighted imaging (DWI) has been shown to be equal to PET/CT in differentiation of tumor and atelectasis. In the same study, T2-weighted imaging was accurate in 76% of cases [48]. MRI Abdomen MRI abdomen with chemical shift sequencing may be used to characterize adrenal nodules when findings on CT chest or CT abdomen are equivocal and FDG-PET or PET/CT is not performed. Indeterminate adrenal nodules may be characterized by chemical shift of in- and out-of-phase MRI to assess for the presence of small intracytoplasmic lipid volume in lipid-poor adenomas. Use of MRI for this purpose is declining because of the high sensitivity and accuracy of PET/CT in identifying adrenal metastases from lung cancer [31]. MRI abdomen with IV contrast may be used to identify small metastatic lesions in the liver when findings are equivocal on CT chest, CT abdomen, FDG-PET, or PET/CT. MRI abdomen with IV contrast has a higher sensitivity than CT, FDG-PET, or PET/CT for detection and characterization of small liver lesions and may be used for more definitive characterization [49].

Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Focused MRI of the chest may be useful in assessment of chest wall or spinal invasion and tumor involvement of mediastinal structures, including the heart, great vessels, and pericardium. MRI assessment of superior sulcus tumors for brachial plexus involvement is standard of care [45]. MRI is superior to CT for detecting involvement of the neural foramina and spinal canal. Dynamic cine MRI with free breathing can determine lack of invasion if there is respiration-coordinated sliding between the tumor and mediastinum or chest wall, and it can also evaluate for phrenic nerve involvement by lymphadenopathy or the primary tumor. Conversely, restriction of tumor motion is not conclusive since inflammation or adhesion may also affect mobility [46,47]. MRI is also capable of distinguishing an obstructing tumor from postobstructive atelectasis. Diffusion- weighted imaging (DWI) has been shown to be equal to PET/CT in differentiation of tumor and atelectasis. In the same study, T2-weighted imaging was accurate in 76% of cases [48]. MRI Abdomen MRI abdomen with chemical shift sequencing may be used to characterize adrenal nodules when findings on CT chest or CT abdomen are equivocal and FDG-PET or PET/CT is not performed. Indeterminate adrenal nodules may be characterized by chemical shift of in- and out-of-phase MRI to assess for the presence of small intracytoplasmic lipid volume in lipid-poor adenomas. Use of MRI for this purpose is declining because of the high sensitivity and accuracy of PET/CT in identifying adrenal metastases from lung cancer [31]. MRI abdomen with IV contrast may be used to identify small metastatic lesions in the liver when findings are equivocal on CT chest, CT abdomen, FDG-PET, or PET/CT. MRI abdomen with IV contrast has a higher sensitivity than CT, FDG-PET, or PET/CT for detection and characterization of small liver lesions and may be used for more definitive characterization [49].

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Noninvasive Clinical Staging of Primary Lung Cancer PCAs

Radiography Chest Chest radiography is not sufficient for staging of NSCLC. Variant 2: Noninvasive initial clinical staging of small-cell lung carcinoma. SCLC is an aggressive form of primary pulmonary neuroendocrine tumor with short doubling time and tendency toward early metastasis [50]. The eighth edition of the TNM staging criteria of the American Joint Committee on Cancer applies to patients with SCLC. The TNM staging criteria is recommended to be used in conjunction with the modified Veterans Administration Lung Study Group (VALSG) classification system distinguishing limited stage (LS) from extensive stage (ES) SCLC because of the ongoing use of the VALSG 2-stage classification system in general clinical practice and clinical trials [51-53]. The 5-year overall survival for LS-SCLC is 20% to 25%, while 5-year survival for ES-SCLC approaches zero [51]. The eighth edition of the TNM criteria of the American Joint Committee on Cancer was developed under the auspices of the International Association for the Study of Lung Cancer and informed by database analysis of nearly 95,000 patients primarily from Europe and Asia [4]. Clinical noninvasive staging by radiologic imaging is the first step in determining the appropriate management for patients with SCLC. Noninvasive Clinical Staging of Primary Lung Cancer N Descriptor In the eighth edition, the N stage is based on location of metastatic nodes. Increasing number of involved nodal stations negatively affects prognosis [5]. A lymph node size threshold of >10 mm in axial short axis diameter is considered abnormal. The prevalence of metastatic lung cancer in thoracic lymph nodes is 30% for nodes that are 10 to 15 mm in short axis diameter and 67% for nodes >15 mm [7]. Nx indicates that lymph nodes cannot be assessed [5]. N0 is consistent with lack of regional node involvement [5]. N1 includes ipsilateral peribronchial, hilar, or intrapulmonary lymph node(s) [5].

Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Radiography Chest Chest radiography is not sufficient for staging of NSCLC. Variant 2: Noninvasive initial clinical staging of small-cell lung carcinoma. SCLC is an aggressive form of primary pulmonary neuroendocrine tumor with short doubling time and tendency toward early metastasis [50]. The eighth edition of the TNM staging criteria of the American Joint Committee on Cancer applies to patients with SCLC. The TNM staging criteria is recommended to be used in conjunction with the modified Veterans Administration Lung Study Group (VALSG) classification system distinguishing limited stage (LS) from extensive stage (ES) SCLC because of the ongoing use of the VALSG 2-stage classification system in general clinical practice and clinical trials [51-53]. The 5-year overall survival for LS-SCLC is 20% to 25%, while 5-year survival for ES-SCLC approaches zero [51]. The eighth edition of the TNM criteria of the American Joint Committee on Cancer was developed under the auspices of the International Association for the Study of Lung Cancer and informed by database analysis of nearly 95,000 patients primarily from Europe and Asia [4]. Clinical noninvasive staging by radiologic imaging is the first step in determining the appropriate management for patients with SCLC. Noninvasive Clinical Staging of Primary Lung Cancer N Descriptor In the eighth edition, the N stage is based on location of metastatic nodes. Increasing number of involved nodal stations negatively affects prognosis [5]. A lymph node size threshold of >10 mm in axial short axis diameter is considered abnormal. The prevalence of metastatic lung cancer in thoracic lymph nodes is 30% for nodes that are 10 to 15 mm in short axis diameter and 67% for nodes >15 mm [7]. Nx indicates that lymph nodes cannot be assessed [5]. N0 is consistent with lack of regional node involvement [5]. N1 includes ipsilateral peribronchial, hilar, or intrapulmonary lymph node(s) [5].

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Noninvasive Clinical Staging of Primary Lung Cancer PCAs

N2 describes ipsilateral mediastinal or subcarinal lymph node(s) [5]. N3 includes contralateral mediastinal or hilar lymph node(s) and any supraclavicular or scalene node on either side [5]. M Descriptor The presence of metastatic lung cancer lesions constitutes stage IV disease. Many patients with SCLC present with metastatic disease [9], and the treatment of stage IV cancers depends on the location and number of lesions. M0 disease is consistent with no distant metastases [5]. The M1 classification is subdivided into three categories: M1a includes satellite nodule(s) in the contralateral lung and cytology proven malignant pleural or pericardial effusion [5]. M1b indicates a single extrathoracic metastasis. This category also includes metastasis in a single nonregional lymph node, considered nodes not in the N descriptor, such as axillary, internal mammary, or abdominal lymph node(s) [5,6]. M1c indicates multiple extrathoracic metastases in one or more organs [5]. Modified VALSG Staging Under the modified VALSG staging classification, SCLC is considered LS disease when it is confined to a single hemithorax (although local extension may be present); the primary tumor and regional nodes can be addressed by a single radiation port; and ipsilateral supraclavicular nodes can be included in the same radiation field as the primary tumor. Contralateral mediastinal lymph nodes and ipsilateral pleural effusion are also considered LS- SCLC [51,52]. ES-SCLC includes disease that is not confined to a single radiation port, malignant pericardial effusion, contralateral pleural effusion, and distant hematogenous metastases [51,52]. The classification of contralateral supraclavicular or hilar lymph nodes is controversial. These nodes should be assessed on a case-by-case basis as to whether they may be feasibly included within a single radiation port [51,52].

Noninvasive Clinical Staging of Primary Lung Cancer PCAs. N2 describes ipsilateral mediastinal or subcarinal lymph node(s) [5]. N3 includes contralateral mediastinal or hilar lymph node(s) and any supraclavicular or scalene node on either side [5]. M Descriptor The presence of metastatic lung cancer lesions constitutes stage IV disease. Many patients with SCLC present with metastatic disease [9], and the treatment of stage IV cancers depends on the location and number of lesions. M0 disease is consistent with no distant metastases [5]. The M1 classification is subdivided into three categories: M1a includes satellite nodule(s) in the contralateral lung and cytology proven malignant pleural or pericardial effusion [5]. M1b indicates a single extrathoracic metastasis. This category also includes metastasis in a single nonregional lymph node, considered nodes not in the N descriptor, such as axillary, internal mammary, or abdominal lymph node(s) [5,6]. M1c indicates multiple extrathoracic metastases in one or more organs [5]. Modified VALSG Staging Under the modified VALSG staging classification, SCLC is considered LS disease when it is confined to a single hemithorax (although local extension may be present); the primary tumor and regional nodes can be addressed by a single radiation port; and ipsilateral supraclavicular nodes can be included in the same radiation field as the primary tumor. Contralateral mediastinal lymph nodes and ipsilateral pleural effusion are also considered LS- SCLC [51,52]. ES-SCLC includes disease that is not confined to a single radiation port, malignant pericardial effusion, contralateral pleural effusion, and distant hematogenous metastases [51,52]. The classification of contralateral supraclavicular or hilar lymph nodes is controversial. These nodes should be assessed on a case-by-case basis as to whether they may be feasibly included within a single radiation port [51,52].

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Noninvasive Clinical Staging of Primary Lung Cancer PCAs

In the combined TNM/VALSG approach for staging of SCLC, T1and T2 lesions and M1a ipsilateral pleural disease correspond with LS-SCLC. T3 and T4 lesions are conditional and may be LS or ES depending on the feasibility of inclusion within a single radiation port. Other M descriptors, including M1a contralateral pleural effusion, M1a pericardial effusion, M1b, and M1c comprise ES-SCLC [54]. CT Chest For patients with known or suspected SCLC, chest CT with IV contrast is recommended. If concurrent CT abdomen is not obtained, the adrenal glands should be covered. Chest CT without IV contrast may also be used. Chest CT is the modality of choice for initial evaluation of the SCLC. A large percentage of SCLCs arise from the central lobar or main bronchi. Consequently, the most common appearance of SCLC on imaging studies is a centrally located lung mass or mediastinal mass with hilar involvement [50]. In two-thirds of patients, tumor Noninvasive Clinical Staging of Primary Lung Cancer tissue encases mediastinal structures, including vessels, airways, and the esophagus [50]. Diagnosis of chest wall invasion on CT can be equivocal in cases of minimal invasion. Radiologic imaging cannot dependably detect visceral pleural invasion. Chest CT with IV contrast can aid in the identification of chest wall invasion by tumor, assessment of extent of mediastinal invasion, evaluation of additional mediastinal and hilar lymph nodes, distinction of central obstructing tumor from surrounding atelectasis, and assessment for liver metastases [50,51]. Unenhanced CT may be better able to characterize adrenal nodules. CT Abdomen and Pelvis CT abdomen and pelvis with oral and IV contrast is recommended in conjunction with CT chest to evaluate for extrathoracic metastasis in SCLC patients. Acquisition of arterial and portal venous phase sequences is advised. CT abdomen without IV contrast may also be obtained. Dual-phase imaging may be useful in this clinical setting.

Noninvasive Clinical Staging of Primary Lung Cancer PCAs. In the combined TNM/VALSG approach for staging of SCLC, T1and T2 lesions and M1a ipsilateral pleural disease correspond with LS-SCLC. T3 and T4 lesions are conditional and may be LS or ES depending on the feasibility of inclusion within a single radiation port. Other M descriptors, including M1a contralateral pleural effusion, M1a pericardial effusion, M1b, and M1c comprise ES-SCLC [54]. CT Chest For patients with known or suspected SCLC, chest CT with IV contrast is recommended. If concurrent CT abdomen is not obtained, the adrenal glands should be covered. Chest CT without IV contrast may also be used. Chest CT is the modality of choice for initial evaluation of the SCLC. A large percentage of SCLCs arise from the central lobar or main bronchi. Consequently, the most common appearance of SCLC on imaging studies is a centrally located lung mass or mediastinal mass with hilar involvement [50]. In two-thirds of patients, tumor Noninvasive Clinical Staging of Primary Lung Cancer tissue encases mediastinal structures, including vessels, airways, and the esophagus [50]. Diagnosis of chest wall invasion on CT can be equivocal in cases of minimal invasion. Radiologic imaging cannot dependably detect visceral pleural invasion. Chest CT with IV contrast can aid in the identification of chest wall invasion by tumor, assessment of extent of mediastinal invasion, evaluation of additional mediastinal and hilar lymph nodes, distinction of central obstructing tumor from surrounding atelectasis, and assessment for liver metastases [50,51]. Unenhanced CT may be better able to characterize adrenal nodules. CT Abdomen and Pelvis CT abdomen and pelvis with oral and IV contrast is recommended in conjunction with CT chest to evaluate for extrathoracic metastasis in SCLC patients. Acquisition of arterial and portal venous phase sequences is advised. CT abdomen without IV contrast may also be obtained. Dual-phase imaging may be useful in this clinical setting.

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Noninvasive Clinical Staging of Primary Lung Cancer PCAs

Up to 60% of SCLC patients have metastases to the abdominal organs at presentation. The liver and adrenal gland are the most frequent site of hematogenous metastasis [55]. Traditionally, CT abdomen with IV contrast has been used to evaluate for extrathoracic metastases and distinguish between LS-SCLC and ES-SCLC. FDG-PET or PET/CT is increasingly used for this purpose and usually obviates the need for a separate CT abdomen and pelvis examination. FDG-PET/CT Skull Base to Mid-Thigh FDG-PET or PET/CT is recommended in patients with clinical stage I or II LS-SCLC being considered for treatment with curative intent. FDG-PET or PET/CT for further staging is optional if ES-SCLC is established. FDG-PET has been shown on average to upstage the disease in up to 18% of patients with clinical LS-SCLC by conventional imaging. A meta-analysis of 7 prospective and retrospective trials found changes in management based on PET findings in 24% to 47% of SCLC patients [52,56,57]. A FDG-PET scan has superior sensitivity and specificity compared with CT in identification of metastatic disease other than brain metastases in SCLC patients [58-60]. Up to 60% of SCLC patients have metastases to the abdominal organs. The liver and adrenal gland are the most frequent site of hematogenous metastasis [55]. Although there is heterogeneous physiologic FDG activity in the liver, the accuracy of FDG-PET and PET/CT for liver metastases is reported at 92% to 100% [37]. When findings are discordant or indeterminate, MRI or biopsy are appropriate strategies to evaluate liver lesions. FDG-PET has sensitivity of 94% and specificity of 82% for characterization of adrenal nodules and is superior to CT alone. Lack of FDG uptake in an adrenal nodule is considered conclusive for benign adrenal adenoma and obviates further workup [31]. Patients with an FDG-avid adrenal nodule as the only site of potential metastatic disease require biopsy confirmation [51].

Noninvasive Clinical Staging of Primary Lung Cancer PCAs. Up to 60% of SCLC patients have metastases to the abdominal organs at presentation. The liver and adrenal gland are the most frequent site of hematogenous metastasis [55]. Traditionally, CT abdomen with IV contrast has been used to evaluate for extrathoracic metastases and distinguish between LS-SCLC and ES-SCLC. FDG-PET or PET/CT is increasingly used for this purpose and usually obviates the need for a separate CT abdomen and pelvis examination. FDG-PET/CT Skull Base to Mid-Thigh FDG-PET or PET/CT is recommended in patients with clinical stage I or II LS-SCLC being considered for treatment with curative intent. FDG-PET or PET/CT for further staging is optional if ES-SCLC is established. FDG-PET has been shown on average to upstage the disease in up to 18% of patients with clinical LS-SCLC by conventional imaging. A meta-analysis of 7 prospective and retrospective trials found changes in management based on PET findings in 24% to 47% of SCLC patients [52,56,57]. A FDG-PET scan has superior sensitivity and specificity compared with CT in identification of metastatic disease other than brain metastases in SCLC patients [58-60]. Up to 60% of SCLC patients have metastases to the abdominal organs. The liver and adrenal gland are the most frequent site of hematogenous metastasis [55]. Although there is heterogeneous physiologic FDG activity in the liver, the accuracy of FDG-PET and PET/CT for liver metastases is reported at 92% to 100% [37]. When findings are discordant or indeterminate, MRI or biopsy are appropriate strategies to evaluate liver lesions. FDG-PET has sensitivity of 94% and specificity of 82% for characterization of adrenal nodules and is superior to CT alone. Lack of FDG uptake in an adrenal nodule is considered conclusive for benign adrenal adenoma and obviates further workup [31]. Patients with an FDG-avid adrenal nodule as the only site of potential metastatic disease require biopsy confirmation [51].

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Noninvasive Clinical Staging of Primary Lung Cancer PCAs

The sensitivity, specificity, accuracy, and negative predictive value of FDG-PET for bone metastases is greater than 90% and is superior to bone scintigraphy [33,34]. MRI Brain MRI brain with IV contrast is recommended in all SCLC patients. MRI brain identifies metastatic lesions in 10% to 15% of newly diagnosed SCLC patients without neurologic symptoms. Up to 12% of patients with otherwise LS-SCLC have intracranial metastases on MRI [61]. MRI is more sensitive than CT for detection of intracranial metastases. MRI brain without IV contrast may be performed. CT Head CT head with IV contrast can be used as an alternate imaging modality in SCLC patients if brain MRI is not performed. Although MRI has greater sensitivity for small brain metastases, CT scanning of the brain is an appropriate method of evaluating for brain metastases in patients with SCLC [51]. Bone Scan Whole Body Tc-99m bone scintigraphy may be used as an alternate imaging modality to evaluate for extrathoracic bone metastasis in SCLC patients if FDG-PET or PET/CT is not performed. Bone metastases are present at the time of diagnosis in up to 37% of SCLCs and are a poor prognostic factor [62,63]. Historically, bone scintigraphy was indicated for the workup of all SCLC patients, but FDG-PET and PET/CT have largely replaced it [51]. Noninvasive Clinical Staging of Primary Lung Cancer MRI Chest MRI chest without and with IV contrast may be indicated in specific clinical circumstances in SCLC patients with equivocal findings on CT chest. Focused MRI of the chest may be useful in assessment of chest wall or spinal invasion and tumor involvement of mediastinal structures including the heart, great vessels, or pericardium. SCLC of the superior sulcus is less common than NSCLC [64] but requires MRI evaluation for locoregional disease affecting the brachial plexus [45]. MRI is superior to CT for detecting involvement of the neural foramina and spinal canal.

Noninvasive Clinical Staging of Primary Lung Cancer PCAs. The sensitivity, specificity, accuracy, and negative predictive value of FDG-PET for bone metastases is greater than 90% and is superior to bone scintigraphy [33,34]. MRI Brain MRI brain with IV contrast is recommended in all SCLC patients. MRI brain identifies metastatic lesions in 10% to 15% of newly diagnosed SCLC patients without neurologic symptoms. Up to 12% of patients with otherwise LS-SCLC have intracranial metastases on MRI [61]. MRI is more sensitive than CT for detection of intracranial metastases. MRI brain without IV contrast may be performed. CT Head CT head with IV contrast can be used as an alternate imaging modality in SCLC patients if brain MRI is not performed. Although MRI has greater sensitivity for small brain metastases, CT scanning of the brain is an appropriate method of evaluating for brain metastases in patients with SCLC [51]. Bone Scan Whole Body Tc-99m bone scintigraphy may be used as an alternate imaging modality to evaluate for extrathoracic bone metastasis in SCLC patients if FDG-PET or PET/CT is not performed. Bone metastases are present at the time of diagnosis in up to 37% of SCLCs and are a poor prognostic factor [62,63]. Historically, bone scintigraphy was indicated for the workup of all SCLC patients, but FDG-PET and PET/CT have largely replaced it [51]. Noninvasive Clinical Staging of Primary Lung Cancer MRI Chest MRI chest without and with IV contrast may be indicated in specific clinical circumstances in SCLC patients with equivocal findings on CT chest. Focused MRI of the chest may be useful in assessment of chest wall or spinal invasion and tumor involvement of mediastinal structures including the heart, great vessels, or pericardium. SCLC of the superior sulcus is less common than NSCLC [64] but requires MRI evaluation for locoregional disease affecting the brachial plexus [45]. MRI is superior to CT for detecting involvement of the neural foramina and spinal canal.

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Hematuria

Causes of hematuria can arise from anywhere along the urinary tract and are generally divided into nephrogenic and urogenic causes. Renal parenchymal disease is the most common benign nephrogenic cause of hematuria [1]. Common benign urogenic causes of hematuria include urolithiasis, infection, and benign prostatic hypertrophy [1]. Malignant causes can occur anywhere in the urinary tract and are the main entity that must be excluded during the imaging evaluation of hematuria. The most common factors associated with development of a urinary malignancy include gross hematuria, male gender, age >35 years, smoking, occupational exposure to chemicals, analgesic abuse, history of urologic disease, irritative voiding symptoms, history of pelvic irradiation, chronic urinary tract infection, exposure to known carcinogenic agents or chemotherapy, and chronic indwelling foreign body [1,2]. Gross hematuria has a high association with malignancy of up to 30% to 40%, and therefore all patients with gross hematuria should have a full urologic workup [1]. Conversely, patients with microhematuria have a low risk of malignancy ranging from 2.6% to 4%, and, in most patients with asymptomatic microhematuria, a cause is never found [1,2]. Patients without risk factors and with an identified benign cause of microhematuria including vigorous exercise, infection, trauma, menstruation, or recent urologic procedure are unlikely to gain any benefit from a complete imaging workup of microhematuria [1,2,5,6]. Patients with suspected urinary tract infection as a cause of microhematuria should have urine cultures performed, preferably before antibiotic therapy, to confirm an infection [1,2]. Patients with a suspected cause of microhematuria, including interstitial cystitis or benign prostatic hyperplasia, should have the appropriate clinical workup before undertaking imaging, including a pelvic examination in women, a rectal examination in men, and cystoscopy [1,2,6]. Interstitial cystitis, in particular, should

Hematuria. Causes of hematuria can arise from anywhere along the urinary tract and are generally divided into nephrogenic and urogenic causes. Renal parenchymal disease is the most common benign nephrogenic cause of hematuria [1]. Common benign urogenic causes of hematuria include urolithiasis, infection, and benign prostatic hypertrophy [1]. Malignant causes can occur anywhere in the urinary tract and are the main entity that must be excluded during the imaging evaluation of hematuria. The most common factors associated with development of a urinary malignancy include gross hematuria, male gender, age >35 years, smoking, occupational exposure to chemicals, analgesic abuse, history of urologic disease, irritative voiding symptoms, history of pelvic irradiation, chronic urinary tract infection, exposure to known carcinogenic agents or chemotherapy, and chronic indwelling foreign body [1,2]. Gross hematuria has a high association with malignancy of up to 30% to 40%, and therefore all patients with gross hematuria should have a full urologic workup [1]. Conversely, patients with microhematuria have a low risk of malignancy ranging from 2.6% to 4%, and, in most patients with asymptomatic microhematuria, a cause is never found [1,2]. Patients without risk factors and with an identified benign cause of microhematuria including vigorous exercise, infection, trauma, menstruation, or recent urologic procedure are unlikely to gain any benefit from a complete imaging workup of microhematuria [1,2,5,6]. Patients with suspected urinary tract infection as a cause of microhematuria should have urine cultures performed, preferably before antibiotic therapy, to confirm an infection [1,2]. Patients with a suspected cause of microhematuria, including interstitial cystitis or benign prostatic hyperplasia, should have the appropriate clinical workup before undertaking imaging, including a pelvic examination in women, a rectal examination in men, and cystoscopy [1,2,6]. Interstitial cystitis, in particular, should

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aJohns Hopkins University School of Medicine, Washington, District of Columbia. bNational Institutes of Health Clinical Center, Bethesda, Maryland. cPanel Chair, Northwestern University, Chicago, Illinois. dPanel Vice-Chair, UT Southwestern Medical Center, Dallas, Texas. eUniversity of Rochester Medical Center, Rochester, New York. fThe University of Texas MD Anderson Cancer Center, Houston, Texas. gUniversity of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, American Society of Nephrology. hUniversity of Washington, Seattle, Washington, American Urological Association. iDuke University Medical Center, Durham, North Carolina. jEmory University School of Medicine, Atlanta, Georgia. kThomas Jefferson University Hospital, Philadelphia, Pennsylvania. lCleveland Clinic, Cleveland, Ohio. mMedical University of South Carolina, Charleston, South Carolina, American Urological Association. nUniversity of Alabama at Birmingham Medical Center, Birmingham, Alabama. oUniversity of California San Francisco School of Medicine, San Francisco, California. pUniversity of Maryland School of Medicine, Baltimore, Maryland. qRhode Island Hospital/The Warren Alpert Medical School of Brown University, Providence, Rhode Island. rSpecialty Chair, University of Alabama at Birmingham, Birmingham, Alabama. 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]

Hematuria. aJohns Hopkins University School of Medicine, Washington, District of Columbia. bNational Institutes of Health Clinical Center, Bethesda, Maryland. cPanel Chair, Northwestern University, Chicago, Illinois. dPanel Vice-Chair, UT Southwestern Medical Center, Dallas, Texas. eUniversity of Rochester Medical Center, Rochester, New York. fThe University of Texas MD Anderson Cancer Center, Houston, Texas. gUniversity of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, American Society of Nephrology. hUniversity of Washington, Seattle, Washington, American Urological Association. iDuke University Medical Center, Durham, North Carolina. jEmory University School of Medicine, Atlanta, Georgia. kThomas Jefferson University Hospital, Philadelphia, Pennsylvania. lCleveland Clinic, Cleveland, Ohio. mMedical University of South Carolina, Charleston, South Carolina, American Urological Association. nUniversity of Alabama at Birmingham Medical Center, Birmingham, Alabama. oUniversity of California San Francisco School of Medicine, San Francisco, California. pUniversity of Maryland School of Medicine, Baltimore, Maryland. qRhode Island Hospital/The Warren Alpert Medical School of Brown University, Providence, Rhode Island. rSpecialty Chair, University of Alabama at Birmingham, Birmingham, Alabama. 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]

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Hematuria be considered in women with chronic pelvic pain along with microhematuria, because this diagnosis is prevalent but often difficult (glomerulonephritis, glomerulonephropathy, acute tubular necrosis, and acute kidney injury) should undergo a concurrent nephrology evaluation, but this should not preclude further evaluation of microhematuria [1,2]. Use of anticoagulant therapy does not alter the urologic evaluation of microhematuria [1,2]. Special Imaging Considerations CT urography (CTU) is an imaging study that is tailored to improve visualization of both the upper and lower urinary tracts. There is variability in the specific parameters, but it usually involves unenhanced images followed by intravenous (IV) contrast-enhanced images, including nephrographic and excretory phases, acquired at least 5 minutes after contrast injection. Alternatively, a split-bolus technique uses an initial loading dose of IV contrast and then obtains a combined nephrographic-excretory phase after a second IV contrast dose; some sites include arterial phase. CTU should use thin-slice acquisition. Reconstruction methods commonly include maximum intensity projection or 3-D volume rendering. For the purposes of this document, we make a distinction between CTU and CT abdomen and pelvis without and with IV contrast. CT abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts and without both the precontrast and excretory phases. MR urography (MRU) is also tailored to improve imaging of the urinary system. Unenhanced MRU relies upon heavily T2-weighted imaging of the intrinsic high signal intensity from urine for evaluation of the urinary tract. IV contrast is administered to provide additional information regarding obstruction, urothelial thickening, focal lesions, and stones. A contrast-enhanced T1-weighted series should include corticomedullary, nephrographic, and excretory phase.

Hematuria. Hematuria be considered in women with chronic pelvic pain along with microhematuria, because this diagnosis is prevalent but often difficult (glomerulonephritis, glomerulonephropathy, acute tubular necrosis, and acute kidney injury) should undergo a concurrent nephrology evaluation, but this should not preclude further evaluation of microhematuria [1,2]. Use of anticoagulant therapy does not alter the urologic evaluation of microhematuria [1,2]. Special Imaging Considerations CT urography (CTU) is an imaging study that is tailored to improve visualization of both the upper and lower urinary tracts. There is variability in the specific parameters, but it usually involves unenhanced images followed by intravenous (IV) contrast-enhanced images, including nephrographic and excretory phases, acquired at least 5 minutes after contrast injection. Alternatively, a split-bolus technique uses an initial loading dose of IV contrast and then obtains a combined nephrographic-excretory phase after a second IV contrast dose; some sites include arterial phase. CTU should use thin-slice acquisition. Reconstruction methods commonly include maximum intensity projection or 3-D volume rendering. For the purposes of this document, we make a distinction between CTU and CT abdomen and pelvis without and with IV contrast. CT abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts and without both the precontrast and excretory phases. MR urography (MRU) is also tailored to improve imaging of the urinary system. Unenhanced MRU relies upon heavily T2-weighted imaging of the intrinsic high signal intensity from urine for evaluation of the urinary tract. IV contrast is administered to provide additional information regarding obstruction, urothelial thickening, focal lesions, and stones. A contrast-enhanced T1-weighted series should include corticomedullary, nephrographic, and excretory phase.

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Thin-slice acquisition and multiplanar imaging should be obtained. For the purposes of this document, we make a distinction between MRU and MRI abdomen and pelvis without and with IV contrast. MRI abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts, without both the precontrast and excretory phases, and without heavily T2-weighted images of the urinary tract. Discussion of Procedures by Variant Variant 1: Microhematuria. No risk factors, or history of recent vigorous exercise, or presence of infection, or viral illness, or present or recent menstruation. Initial imaging. Patients without risk factors and with a known benign cause of microhematuria are unlikely to gain any benefit from a complete imaging workup of microscopic hematuria. Multiple studies have shown that patients in this category do not derive any benefit from imaging [1,2,6,7]. Arteriography Kidney Arteriography is not used as a first-line imaging modality for the evaluation of microhematuria. There is no relevant literature regarding the use of arteriography for the initial evaluation of microhematuria. CT Abdomen and Pelvis For the purposes of this document, we make a distinction between CTU and CT abdomen and pelvis without and with IV contrast. CT abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts and without both the precontrast and excretory phases. CT without IV contrast may be a reasonable option in the setting of microhematuria in patients <50 years of age [8]. There is no relevant literature regarding the use of CT with IV contrast for the initial evaluation of microhematuria. CTU CTU CTU is not useful as a first-line imaging modality for the evaluation of microhematuria in patients with no known risk factors and with an identified benign cause of microhematuria.

Hematuria. Thin-slice acquisition and multiplanar imaging should be obtained. For the purposes of this document, we make a distinction between MRU and MRI abdomen and pelvis without and with IV contrast. MRI abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts, without both the precontrast and excretory phases, and without heavily T2-weighted images of the urinary tract. Discussion of Procedures by Variant Variant 1: Microhematuria. No risk factors, or history of recent vigorous exercise, or presence of infection, or viral illness, or present or recent menstruation. Initial imaging. Patients without risk factors and with a known benign cause of microhematuria are unlikely to gain any benefit from a complete imaging workup of microscopic hematuria. Multiple studies have shown that patients in this category do not derive any benefit from imaging [1,2,6,7]. Arteriography Kidney Arteriography is not used as a first-line imaging modality for the evaluation of microhematuria. There is no relevant literature regarding the use of arteriography for the initial evaluation of microhematuria. CT Abdomen and Pelvis For the purposes of this document, we make a distinction between CTU and CT abdomen and pelvis without and with IV contrast. CT abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts and without both the precontrast and excretory phases. CT without IV contrast may be a reasonable option in the setting of microhematuria in patients <50 years of age [8]. There is no relevant literature regarding the use of CT with IV contrast for the initial evaluation of microhematuria. CTU CTU CTU is not useful as a first-line imaging modality for the evaluation of microhematuria in patients with no known risk factors and with an identified benign cause of microhematuria.

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Lisanti et al [7] found that in 442 patients <40 years of age and without risk factors, no patient had a malignancy-related hematuria finding at CTU. MRU MRU is not useful as a first-line imaging modality for the evaluation of microhematuria in patients with no known risk factors and with an identified benign cause of microhematuria. There is no relevant literature regarding the use of MRU for the initial evaluation of microhematuria. Hematuria MRI Abdomen and Pelvis For the purposes of this document, we make a distinction between MRU and MRI abdomen and pelvis without and with IV contrast. MRI abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts, without both the precontrast and excretory phases, and without heavily T2-weighted images of the urinary tract. There is no relevant literature regarding the use of MRI for the initial evaluation of microhematuria. Radiography Abdomen and Pelvis Conventional radiographs of the abdomen and pelvis (KUB) are not used as a first-line imaging modality for the evaluation of hematuria. There is no relevant literature regarding the use of radiography for the initial evaluation of microhematuria. Radiography Intravenous Urography IV urography (IVU) is no longer used as a first-line imaging modality for the evaluation of hematuria. There is no relevant literature regarding the use of IVU for the initial evaluation of microhematuria. US Kidneys and Bladder Retroperitoneal Ultrasound (US) is not useful as a first-line imaging modality for the evaluation of microhematuria with no known risk factors and with an identified benign cause of microhematuria. Variant 2: Microhematuria. Patients with risk factors, without any of the following: history of recent vigorous exercise, or presence of infection or viral illness, or present or recent menstruation, or renal parenchymal disease. Initial imaging.

Hematuria. Lisanti et al [7] found that in 442 patients <40 years of age and without risk factors, no patient had a malignancy-related hematuria finding at CTU. MRU MRU is not useful as a first-line imaging modality for the evaluation of microhematuria in patients with no known risk factors and with an identified benign cause of microhematuria. There is no relevant literature regarding the use of MRU for the initial evaluation of microhematuria. Hematuria MRI Abdomen and Pelvis For the purposes of this document, we make a distinction between MRU and MRI abdomen and pelvis without and with IV contrast. MRI abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts, without both the precontrast and excretory phases, and without heavily T2-weighted images of the urinary tract. There is no relevant literature regarding the use of MRI for the initial evaluation of microhematuria. Radiography Abdomen and Pelvis Conventional radiographs of the abdomen and pelvis (KUB) are not used as a first-line imaging modality for the evaluation of hematuria. There is no relevant literature regarding the use of radiography for the initial evaluation of microhematuria. Radiography Intravenous Urography IV urography (IVU) is no longer used as a first-line imaging modality for the evaluation of hematuria. There is no relevant literature regarding the use of IVU for the initial evaluation of microhematuria. US Kidneys and Bladder Retroperitoneal Ultrasound (US) is not useful as a first-line imaging modality for the evaluation of microhematuria with no known risk factors and with an identified benign cause of microhematuria. Variant 2: Microhematuria. Patients with risk factors, without any of the following: history of recent vigorous exercise, or presence of infection or viral illness, or present or recent menstruation, or renal parenchymal disease. Initial imaging.

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Arteriography Kidney Arteriography is not used as a first-line imaging modality for the evaluation of microhematuria. There is no relevant literature regarding the use of arteriography for the initial evaluation of microhematuria. CT Abdomen and Pelvis For the purposes of this document, we make a distinction between CTU and CT abdomen and pelvis without and with IV contrast. CT abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts and without both the precontrast and excretory phases. There is no relevant literature regarding the use of CT with IV contrast or CT without IV contrast in this patient population with microhematuria. Initial studies compared CTU with other modalities but without direct comparison to conventional contrast-enhanced CT. However, in current practice, CTU has replaced conventional CT in this situation because of improved detection of urothelial lesions on CTU. CTU CTU CTU has been shown to be the imaging study of choice for the evaluation of microhematuria because it can evaluate both nephrogenic and urogenic causes of hematuria [1,2,9-12]. In a meta-analysis, CTU proved to be a very sensitive and specific method for the detection of urothelial malignancy with pooled sensitivity of 96% and pooled specificity of 99% and was superior in direct comparison to IVU in terms of sensitivity and specificity [10]. For the detection of upper tract lesions (kidneys and ureters), CTU has been shown to be superior to IVU with an accuracy of 99.6% compared with 84.9% for IVU [12]. CTU has also been shown to be useful for the detection of lower tract lesions (bladder) [11,13]. In one study of 242 patients with microhematuria, the specificity and accuracy of CTU for the detection of lower tract lesions was 98.8% and 97.2%, respectively [11]. In comparison with MRU, one study showed that CTU provided better visibility of the urothelial structures and improved diagnostic confidence [14].

Hematuria. Arteriography Kidney Arteriography is not used as a first-line imaging modality for the evaluation of microhematuria. There is no relevant literature regarding the use of arteriography for the initial evaluation of microhematuria. CT Abdomen and Pelvis For the purposes of this document, we make a distinction between CTU and CT abdomen and pelvis without and with IV contrast. CT abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts and without both the precontrast and excretory phases. There is no relevant literature regarding the use of CT with IV contrast or CT without IV contrast in this patient population with microhematuria. Initial studies compared CTU with other modalities but without direct comparison to conventional contrast-enhanced CT. However, in current practice, CTU has replaced conventional CT in this situation because of improved detection of urothelial lesions on CTU. CTU CTU CTU has been shown to be the imaging study of choice for the evaluation of microhematuria because it can evaluate both nephrogenic and urogenic causes of hematuria [1,2,9-12]. In a meta-analysis, CTU proved to be a very sensitive and specific method for the detection of urothelial malignancy with pooled sensitivity of 96% and pooled specificity of 99% and was superior in direct comparison to IVU in terms of sensitivity and specificity [10]. For the detection of upper tract lesions (kidneys and ureters), CTU has been shown to be superior to IVU with an accuracy of 99.6% compared with 84.9% for IVU [12]. CTU has also been shown to be useful for the detection of lower tract lesions (bladder) [11,13]. In one study of 242 patients with microhematuria, the specificity and accuracy of CTU for the detection of lower tract lesions was 98.8% and 97.2%, respectively [11]. In comparison with MRU, one study showed that CTU provided better visibility of the urothelial structures and improved diagnostic confidence [14].

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MRU MRU has decreased spatial resolution compared with CTU. Also, small nonobstructive renal calculi and other calcifications as well as small urothelial lesions may be difficult to detect at MRU [15]. However, MRI has shown comparable accuracy to CT in the detection and characterization of renal masses [16]. Hematuria MRI Abdomen and Pelvis For the purposes of this document, we make a distinction between MRU and MRI abdomen and pelvis without and with IV contrast. MRI abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts, without both the precontrast and excretory phases, and without heavily T2-weighted images of the urinary tract. There is no relevant literature regarding the use of routine MRI with IV contrast in this patient population with microhematuria. Radiography Abdomen and Pelvis Conventional radiographs of the abdomen and pelvis (KUB) are not used as a first-line imaging modality for the evaluation of hematuria. There is no relevant literature regarding the use of radiographs for the initial evaluation of microhematuria. Radiography Intravenous Urography IVU is no longer used as a first-line imaging modality for the evaluation of hematuria. Multiple studies have shown that IVU has a low sensitivity for the detection of renal masses and urinary tract abnormalities in general compared with CT [9,10]. US Kidneys and Bladder Retroperitoneal US is not used as a first-line imaging modality for the evaluation of microhematuria. One study of 141 patients showed US had a lower sensitivity for the detection of urinary tract abnormalities compared with both CTU and MRU [17]. However, a recent large prospective study suggests that kidney and bladder US may be adequate for initial evaluation of microhematuria [18]. In this study, urinary cancer was diagnosed in 0.4% of patients who presented with microscopic hematuria, and all the patients had a renal carcinoma [18]. Variant 3: Microhematuria.

Hematuria. MRU MRU has decreased spatial resolution compared with CTU. Also, small nonobstructive renal calculi and other calcifications as well as small urothelial lesions may be difficult to detect at MRU [15]. However, MRI has shown comparable accuracy to CT in the detection and characterization of renal masses [16]. Hematuria MRI Abdomen and Pelvis For the purposes of this document, we make a distinction between MRU and MRI abdomen and pelvis without and with IV contrast. MRI abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts, without both the precontrast and excretory phases, and without heavily T2-weighted images of the urinary tract. There is no relevant literature regarding the use of routine MRI with IV contrast in this patient population with microhematuria. Radiography Abdomen and Pelvis Conventional radiographs of the abdomen and pelvis (KUB) are not used as a first-line imaging modality for the evaluation of hematuria. There is no relevant literature regarding the use of radiographs for the initial evaluation of microhematuria. Radiography Intravenous Urography IVU is no longer used as a first-line imaging modality for the evaluation of hematuria. Multiple studies have shown that IVU has a low sensitivity for the detection of renal masses and urinary tract abnormalities in general compared with CT [9,10]. US Kidneys and Bladder Retroperitoneal US is not used as a first-line imaging modality for the evaluation of microhematuria. One study of 141 patients showed US had a lower sensitivity for the detection of urinary tract abnormalities compared with both CTU and MRU [17]. However, a recent large prospective study suggests that kidney and bladder US may be adequate for initial evaluation of microhematuria [18]. In this study, urinary cancer was diagnosed in 0.4% of patients who presented with microscopic hematuria, and all the patients had a renal carcinoma [18]. Variant 3: Microhematuria.

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Pregnant patient. Initial imaging. Pregnant patients present with microhematuria at a rate similar to nonpregnant patients, and the rate of malignancy in this group is low [2,19]. Arteriography Kidney Arteriography is not used as a first-line imaging modality for the evaluation of microhematuria in pregnancy. There is no relevant literature regarding the use of arteriography for the initial evaluation of microhematuria. CT Abdomen and Pelvis CT is not used as a first-line imaging modality for the evaluation of microhematuria in pregnant patients secondary to the risks of radiation exposure to the fetus. The incidence of asymptomatic microhematuria in pregnant women is similar to nonpregnant women, and the rate of malignancy in this group is low [2]. CTU CTU is not used as a first-line imaging modality for the evaluation of microhematuria in pregnant patients secondary to the risks of radiation exposure to the fetus. The incidence of asymptomatic microhematuria in pregnant women is similar to nonpregnant women, and the rate of malignancy in this group is low [2]. MRU MRU MRU without and with IV contrast is not used as a first-line imaging modality for the evaluation of microhematuria in pregnant patients. The incidence of asymptomatic microhematuria in pregnant women is similar to nonpregnant women, and the rate of malignancy in this group is low [2]. MRU without IV contrast during pregnancy is a reasonable choice with a full workup after delivery once gynecologic bleeding and other benign causes (such as infection) have been excluded [2]. MRI with IV contrast should be avoided in pregnant patients because of uncertainty of effects of gadolinium contrast on the fetus. See the Safety Considerations in Pregnant Patients section below. MRI Abdomen and Pelvis The incidence of asymptomatic microhematuria in pregnant women is similar to nonpregnant women, and the rate of malignancy in this group is low [2].

Hematuria. Pregnant patient. Initial imaging. Pregnant patients present with microhematuria at a rate similar to nonpregnant patients, and the rate of malignancy in this group is low [2,19]. Arteriography Kidney Arteriography is not used as a first-line imaging modality for the evaluation of microhematuria in pregnancy. There is no relevant literature regarding the use of arteriography for the initial evaluation of microhematuria. CT Abdomen and Pelvis CT is not used as a first-line imaging modality for the evaluation of microhematuria in pregnant patients secondary to the risks of radiation exposure to the fetus. The incidence of asymptomatic microhematuria in pregnant women is similar to nonpregnant women, and the rate of malignancy in this group is low [2]. CTU CTU is not used as a first-line imaging modality for the evaluation of microhematuria in pregnant patients secondary to the risks of radiation exposure to the fetus. The incidence of asymptomatic microhematuria in pregnant women is similar to nonpregnant women, and the rate of malignancy in this group is low [2]. MRU MRU MRU without and with IV contrast is not used as a first-line imaging modality for the evaluation of microhematuria in pregnant patients. The incidence of asymptomatic microhematuria in pregnant women is similar to nonpregnant women, and the rate of malignancy in this group is low [2]. MRU without IV contrast during pregnancy is a reasonable choice with a full workup after delivery once gynecologic bleeding and other benign causes (such as infection) have been excluded [2]. MRI with IV contrast should be avoided in pregnant patients because of uncertainty of effects of gadolinium contrast on the fetus. See the Safety Considerations in Pregnant Patients section below. MRI Abdomen and Pelvis The incidence of asymptomatic microhematuria in pregnant women is similar to nonpregnant women, and the rate of malignancy in this group is low [2].

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MRI abdomen and pelvis with and without IV contrast is not used as a first- line imaging modality for the evaluation of microhematuria in pregnant patients. MRI abdomen and pelvis without IV contrast is not used as a first-line imaging modality because of the absence of heavily T2-weighted images of the urinary tract. Hematuria MRI with IV contrast should be avoided in pregnant patients because of the uncertainty of effects of gadolinium contrast on the fetus. See the Safety Considerations in Pregnant Patients section below. Radiography Abdomen and Pelvis Conventional radiographs of the abdomen and pelvis (KUB) are not used as a first-line imaging modality for the evaluation of hematuria in pregnancy. There is no relevant literature regarding the use of radiographs for the initial evaluation of microhematuria. Radiography Intravenous Urography IVU is not used as a first-line imaging modality for the evaluation of microhematuria in pregnancy. There is no relevant literature regarding the use of IVU for the initial evaluation of microhematuria. US Kidneys and Bladder Retroperitoneal The incidence of asymptomatic microhematuria in pregnant women is similar to nonpregnant women, and the rate of malignancy in this group is low [2]. US during pregnancy is a reasonable choice with a full workup after delivery once gynecologic bleeding and other benign causes (such as infection) have been excluded [2,19]. Variant 4: Gross hematuria. Initial imaging. Arteriography Kidney Arteriography is not used as a first-line imaging modality for the evaluation of gross hematuria. There is no relevant literature regarding the use of arteriography for the initial evaluation of gross hematuria. CT Abdomen and Pelvis For the purposes of this document, we make a distinction between CTU and CT abdomen and pelvis without and with IV contrast.

Hematuria. MRI abdomen and pelvis with and without IV contrast is not used as a first- line imaging modality for the evaluation of microhematuria in pregnant patients. MRI abdomen and pelvis without IV contrast is not used as a first-line imaging modality because of the absence of heavily T2-weighted images of the urinary tract. Hematuria MRI with IV contrast should be avoided in pregnant patients because of the uncertainty of effects of gadolinium contrast on the fetus. See the Safety Considerations in Pregnant Patients section below. Radiography Abdomen and Pelvis Conventional radiographs of the abdomen and pelvis (KUB) are not used as a first-line imaging modality for the evaluation of hematuria in pregnancy. There is no relevant literature regarding the use of radiographs for the initial evaluation of microhematuria. Radiography Intravenous Urography IVU is not used as a first-line imaging modality for the evaluation of microhematuria in pregnancy. There is no relevant literature regarding the use of IVU for the initial evaluation of microhematuria. US Kidneys and Bladder Retroperitoneal The incidence of asymptomatic microhematuria in pregnant women is similar to nonpregnant women, and the rate of malignancy in this group is low [2]. US during pregnancy is a reasonable choice with a full workup after delivery once gynecologic bleeding and other benign causes (such as infection) have been excluded [2,19]. Variant 4: Gross hematuria. Initial imaging. Arteriography Kidney Arteriography is not used as a first-line imaging modality for the evaluation of gross hematuria. There is no relevant literature regarding the use of arteriography for the initial evaluation of gross hematuria. CT Abdomen and Pelvis For the purposes of this document, we make a distinction between CTU and CT abdomen and pelvis without and with IV contrast.

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Hematuria

CT abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts and without both the precontrast and excretory phases. There is no relevant literature regarding the use of CT with IV contrast or CT without IV contrast in the evaluation of gross hematuria. CTU CTU The usefulness of CTU in the evaluation of gross hematuria has been mixed [11,13,20-23]. In one study of 150 patients, the sensitivity and specificity of CTU for the detection of bladder malignancy was 61.5% and 94.9% using cystoscopy as the reference standard [21]. However, in another study of 435 patients, CTU performed comparably to cystoscopy for the detection of bladder malignancy with sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 87%, 99%, 91%, and 98%, compared with 87%, 100%, 98%, and 98%, respectively, for cystoscopy [22]. The recent DETECT (Detecting Bladder Cancer Using the UroMark Test) 1 study recommends CTU for gross hematuria because of an upper tract tumor rate of 0.8% [18]. MRU There is no relevant literature regarding the use of MRU in patients with gross hematuria. Direct comparison of MRI and CTU sensitivity for evaluation of urothelial lesions in gross hematuria is not available in the literature. MRI Abdomen and Pelvis For the purposes of this document, we make a distinction between MRU and MRI abdomen and pelvis without and with IV contrast. MRI abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts, without both the precontrast and excretory phases, and without heavily T2-weighted images of the urinary tract. MRI without contrast may be helpful for the evaluation of gross hematuria. In one study of 130 patients, MRI had a sensitivity of 98.5% and PPV of 100% for determining the cause of gross hematuria, using cystoscopy and histopathology as the reference standards [24].

Hematuria. CT abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts and without both the precontrast and excretory phases. There is no relevant literature regarding the use of CT with IV contrast or CT without IV contrast in the evaluation of gross hematuria. CTU CTU The usefulness of CTU in the evaluation of gross hematuria has been mixed [11,13,20-23]. In one study of 150 patients, the sensitivity and specificity of CTU for the detection of bladder malignancy was 61.5% and 94.9% using cystoscopy as the reference standard [21]. However, in another study of 435 patients, CTU performed comparably to cystoscopy for the detection of bladder malignancy with sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 87%, 99%, 91%, and 98%, compared with 87%, 100%, 98%, and 98%, respectively, for cystoscopy [22]. The recent DETECT (Detecting Bladder Cancer Using the UroMark Test) 1 study recommends CTU for gross hematuria because of an upper tract tumor rate of 0.8% [18]. MRU There is no relevant literature regarding the use of MRU in patients with gross hematuria. Direct comparison of MRI and CTU sensitivity for evaluation of urothelial lesions in gross hematuria is not available in the literature. MRI Abdomen and Pelvis For the purposes of this document, we make a distinction between MRU and MRI abdomen and pelvis without and with IV contrast. MRI abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts, without both the precontrast and excretory phases, and without heavily T2-weighted images of the urinary tract. MRI without contrast may be helpful for the evaluation of gross hematuria. In one study of 130 patients, MRI had a sensitivity of 98.5% and PPV of 100% for determining the cause of gross hematuria, using cystoscopy and histopathology as the reference standards [24].

69490

acrac_69448_0

Chronic Dyspnea Noncardiovascular Origin

Introduction/Background Dyspnea is the subjective experience of breathing discomfort [1], often described as a feeling of breathlessness, or shortness of breath. The perception of dyspnea derives from the interactions of physiological, psychological, environmental, and social factors that may provoke various physiologic and behavioral responses. Clinical history and physical examination may provide insight into the cause or causes of dyspnea; however, laboratory and ancillary tests are also often necessary. Overview of Imaging Modalities Radiography Chest The workup of chronic dyspnea is influenced by its severity, the rate of worsening, and the presence or absence of risk factors and other symptoms. The initial evaluation is aimed at determining whether the cause is related to cardiovascular disease, pulmonary disease, a combination of both, or neither. A chest radiograph will typically be performed in the initial workup. The results of the chest radiograph can help guide, and sometimes eliminate the need for, further investigation. Using an algorithmic approach, the combination of chest radiograph and laboratory evaluation may result in a specific diagnosis in one-third of cases [7]. CT Chest CT has an important role in the imaging evaluation of chronic dyspnea. It is useful when a radiographic abnormality requires further characterization or clinical findings necessitate additional imaging despite a normal radiograph [8,9]. For most routine applications, intravenous (IV) contrast is not needed, although it may be added when vascular abnormalities are in the differential diagnosis. CT protocols should be tailored to meet individual needs and may be determined based on radiographs and clinical features. For dyspnea, thin collimation of the lung parenchyma is essential. Most modern scanners allow this without additional data to be acquired.

Chronic Dyspnea Noncardiovascular Origin. Introduction/Background Dyspnea is the subjective experience of breathing discomfort [1], often described as a feeling of breathlessness, or shortness of breath. The perception of dyspnea derives from the interactions of physiological, psychological, environmental, and social factors that may provoke various physiologic and behavioral responses. Clinical history and physical examination may provide insight into the cause or causes of dyspnea; however, laboratory and ancillary tests are also often necessary. Overview of Imaging Modalities Radiography Chest The workup of chronic dyspnea is influenced by its severity, the rate of worsening, and the presence or absence of risk factors and other symptoms. The initial evaluation is aimed at determining whether the cause is related to cardiovascular disease, pulmonary disease, a combination of both, or neither. A chest radiograph will typically be performed in the initial workup. The results of the chest radiograph can help guide, and sometimes eliminate the need for, further investigation. Using an algorithmic approach, the combination of chest radiograph and laboratory evaluation may result in a specific diagnosis in one-third of cases [7]. CT Chest CT has an important role in the imaging evaluation of chronic dyspnea. It is useful when a radiographic abnormality requires further characterization or clinical findings necessitate additional imaging despite a normal radiograph [8,9]. For most routine applications, intravenous (IV) contrast is not needed, although it may be added when vascular abnormalities are in the differential diagnosis. CT protocols should be tailored to meet individual needs and may be determined based on radiographs and clinical features. For dyspnea, thin collimation of the lung parenchyma is essential. Most modern scanners allow this without additional data to be acquired.

69448

acrac_69448_1

Chronic Dyspnea Noncardiovascular Origin

Adjuncts, such as expiratory images, prone images, and dynamic imaging of the airways, may be applied in certain clinical situations; therefore, knowledge of the suspected diagnosis is essential for planning the CT scan. MRI Chest MRI does not currently have a significant role in the evaluation of chronic dyspnea that is not of cardiovascular origin. However, MRI may play a role in the workup of congenital anomalies and diseases of the Reprint requests to: [email protected] Chronic Dyspnea-Noncardiovascular Origin cardiopulmonary axis where both pulmonary imaging and cardiac imaging are desired in a single examination, and in the tissue characterization and assessment of extent of thoracic lesions. FDG-PET/CT Skull Base to Mid-Thigh Functional information from PET using the tracer fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG)/CT can complement morphologic information derived from chest radiographs and CT. Attempts have been made to determine the efficacy of FDG-PET/CT in the behavior of inflammatory cells, extent of active lung disease, and response to therapy [10]. To date, evidence is limited to small series and has not been subjected to use in pharmacologic trials. US Chest Transthoracic ultrasound (US) imaging can be used for assessment of the lung periphery and pleura. Major advantages include portability, ease of use, and real-time imaging capability. US can target abnormalities and complement other imaging studies. It is particularly suited to bedside evaluation. Examples of uses in chronic dyspnea include the assessment of pleural and chest wall pathology, peripheral lung abnormalities, evaluation of diaphragmatic function, and guidance of interventional procedures. Discussion of Procedures by Variant Variant 1: Chronic dyspnea. Unclear etiology. Initial imaging. Radiography Chest The chest radiograph should generally be the initial imaging study in chronic dyspnea. Pratter et al [11] reported that it added sufficient information to justify its routine use.

Chronic Dyspnea Noncardiovascular Origin. Adjuncts, such as expiratory images, prone images, and dynamic imaging of the airways, may be applied in certain clinical situations; therefore, knowledge of the suspected diagnosis is essential for planning the CT scan. MRI Chest MRI does not currently have a significant role in the evaluation of chronic dyspnea that is not of cardiovascular origin. However, MRI may play a role in the workup of congenital anomalies and diseases of the Reprint requests to: [email protected] Chronic Dyspnea-Noncardiovascular Origin cardiopulmonary axis where both pulmonary imaging and cardiac imaging are desired in a single examination, and in the tissue characterization and assessment of extent of thoracic lesions. FDG-PET/CT Skull Base to Mid-Thigh Functional information from PET using the tracer fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG)/CT can complement morphologic information derived from chest radiographs and CT. Attempts have been made to determine the efficacy of FDG-PET/CT in the behavior of inflammatory cells, extent of active lung disease, and response to therapy [10]. To date, evidence is limited to small series and has not been subjected to use in pharmacologic trials. US Chest Transthoracic ultrasound (US) imaging can be used for assessment of the lung periphery and pleura. Major advantages include portability, ease of use, and real-time imaging capability. US can target abnormalities and complement other imaging studies. It is particularly suited to bedside evaluation. Examples of uses in chronic dyspnea include the assessment of pleural and chest wall pathology, peripheral lung abnormalities, evaluation of diaphragmatic function, and guidance of interventional procedures. Discussion of Procedures by Variant Variant 1: Chronic dyspnea. Unclear etiology. Initial imaging. Radiography Chest The chest radiograph should generally be the initial imaging study in chronic dyspnea. Pratter et al [11] reported that it added sufficient information to justify its routine use.

69448

acrac_69448_2

Chronic Dyspnea Noncardiovascular Origin

In conjunction with cardiomyopathy, two-thirds of cases of chronic dyspnea in a pulmonary clinic were caused by asthma, COPD, and ILD. Pratter et al [7] later employed a prospective algorithmic approach to chronic dyspnea that used the chest radiograph as part of a Tier I evaluation. Karnani et al [2] advocated an algorithm that used the history and physical examination to guide appropriate testing, with the chest radiograph a component of a Level 1 diagnostic workup. Wahls [3] addressed the importance of the chest radiograph in the initial workup of chronic dyspnea in patients both with and without other physical examination findings. A chest radiograph might reveal a wide variety of abnormalities in chronic dyspnea that may guide further imaging choices as outlined in subsequent variants. Examples include COPD, ILD, central airways disease, and pleural, chest wall, and diaphragmatic pathology. CT Chest In cases where the chest radiograph is normal or does not provide a direct answer, CT can be beneficial for documenting abnormalities not identified on a chest radiograph and guiding further workup [8,12]. In the Multi- Ethnic Study of Atherosclerosis lung study, CT imaging for parenchymal disease was considered to be the most informative imaging test [13]. MRI Chest MRI has not been evaluated in a systematic manner for the assessment of patients with nonspecific chronic dyspnea, although it may have a role in specific clinical situations. US Chest Transthoracic US has good test characteristics for peripheral thoracic abnormalities, although it does not provide the comprehensive evaluation that CT does in the setting of an unspecified cause. FDG-PET/CT Skull Base to Mid-Thigh FDG-PET/CT has not been evaluated in a systematic manner for the assessment of patients with nonspecific chronic dyspnea, although it may have a role in specific clinical situations. Variant 2: Chronic dyspnea. Suspected chronic obstructive pulmonary disease (COPD). Initial imaging.

Chronic Dyspnea Noncardiovascular Origin. In conjunction with cardiomyopathy, two-thirds of cases of chronic dyspnea in a pulmonary clinic were caused by asthma, COPD, and ILD. Pratter et al [7] later employed a prospective algorithmic approach to chronic dyspnea that used the chest radiograph as part of a Tier I evaluation. Karnani et al [2] advocated an algorithm that used the history and physical examination to guide appropriate testing, with the chest radiograph a component of a Level 1 diagnostic workup. Wahls [3] addressed the importance of the chest radiograph in the initial workup of chronic dyspnea in patients both with and without other physical examination findings. A chest radiograph might reveal a wide variety of abnormalities in chronic dyspnea that may guide further imaging choices as outlined in subsequent variants. Examples include COPD, ILD, central airways disease, and pleural, chest wall, and diaphragmatic pathology. CT Chest In cases where the chest radiograph is normal or does not provide a direct answer, CT can be beneficial for documenting abnormalities not identified on a chest radiograph and guiding further workup [8,12]. In the Multi- Ethnic Study of Atherosclerosis lung study, CT imaging for parenchymal disease was considered to be the most informative imaging test [13]. MRI Chest MRI has not been evaluated in a systematic manner for the assessment of patients with nonspecific chronic dyspnea, although it may have a role in specific clinical situations. US Chest Transthoracic US has good test characteristics for peripheral thoracic abnormalities, although it does not provide the comprehensive evaluation that CT does in the setting of an unspecified cause. FDG-PET/CT Skull Base to Mid-Thigh FDG-PET/CT has not been evaluated in a systematic manner for the assessment of patients with nonspecific chronic dyspnea, although it may have a role in specific clinical situations. Variant 2: Chronic dyspnea. Suspected chronic obstructive pulmonary disease (COPD). Initial imaging.

69448

acrac_69448_3

Chronic Dyspnea Noncardiovascular Origin

Radiography Chest In COPD, a radiograph can help exclude alternative diagnoses and evaluate for comorbidities and complications [14]. Wallace et al [15] reported that 14% of chest radiographs ordered during COPD evaluation detected potentially treatable causes of dyspnea other than COPD and lung cancer and that 84% of radiographs assisted management. Chronic Dyspnea-Noncardiovascular Origin CT Chest CT has greater sensitivity and specificity than a chest radiograph in determining the type, extent, and distribution of emphysema and bronchial wall abnormalities [16]. CT is able to identify early changes of COPD in asymptomatic and spirometrically normal smokers [17]. It has shown that visual assessments of emphysema and airway disease are accurate and reproducible [18]. In addition, quantitative CT-derived parameters correlate with pulmonary function tests and can be used as imaging biomarkers to follow disease progression [19-23]. Findings have been shown to correlate with patient-reported measures [24-26] and to predict health status in COPD [27]. CT-based phenotypes have prognostic value in predicting future hospitalization, symptomatic decline, and mortality [28,29]. Expiratory CT has been reported to reflect airflow limitation and correlates well with levels of dyspnea [30]. MRI Chest Numerous MRI techniques are available to evaluate COPD, including hyperpolarized helium, T1 oxygen- enhanced mapping, and equilibrium signal mapping [31-33]. While predominately the subject of research, small studies have shown good correlation with CT-derived measures and provide a rationale for the use of MRI when quantitative imaging measures are needed. US Chest US may have a role in defining pleural or diaphragmatic complications related to COPD, but there is no supporting evidence for its use as a diagnostic technique for this condition. FDG-PET/CT Skull Base to Mid-Thigh There are no primary data to support the use of FDG-PET/CT to diagnose or manage COPD.

Chronic Dyspnea Noncardiovascular Origin. Radiography Chest In COPD, a radiograph can help exclude alternative diagnoses and evaluate for comorbidities and complications [14]. Wallace et al [15] reported that 14% of chest radiographs ordered during COPD evaluation detected potentially treatable causes of dyspnea other than COPD and lung cancer and that 84% of radiographs assisted management. Chronic Dyspnea-Noncardiovascular Origin CT Chest CT has greater sensitivity and specificity than a chest radiograph in determining the type, extent, and distribution of emphysema and bronchial wall abnormalities [16]. CT is able to identify early changes of COPD in asymptomatic and spirometrically normal smokers [17]. It has shown that visual assessments of emphysema and airway disease are accurate and reproducible [18]. In addition, quantitative CT-derived parameters correlate with pulmonary function tests and can be used as imaging biomarkers to follow disease progression [19-23]. Findings have been shown to correlate with patient-reported measures [24-26] and to predict health status in COPD [27]. CT-based phenotypes have prognostic value in predicting future hospitalization, symptomatic decline, and mortality [28,29]. Expiratory CT has been reported to reflect airflow limitation and correlates well with levels of dyspnea [30]. MRI Chest Numerous MRI techniques are available to evaluate COPD, including hyperpolarized helium, T1 oxygen- enhanced mapping, and equilibrium signal mapping [31-33]. While predominately the subject of research, small studies have shown good correlation with CT-derived measures and provide a rationale for the use of MRI when quantitative imaging measures are needed. US Chest US may have a role in defining pleural or diaphragmatic complications related to COPD, but there is no supporting evidence for its use as a diagnostic technique for this condition. FDG-PET/CT Skull Base to Mid-Thigh There are no primary data to support the use of FDG-PET/CT to diagnose or manage COPD.

69448

acrac_69448_4

Chronic Dyspnea Noncardiovascular Origin

Variant 3: Chronic dyspnea. Suspected central airways disease. Initial imaging. Radiography Chest Chest radiographs have the potential to identify conditions of the trachea, with accuracy dependent on the condition to be identified. Compared to CT, radiographs have an accuracy of 89% [34]. It should be noted that radiographic findings may be normal or nonspecific. In a single-institution retrospective study of tracheal neoplasms, <50% were directly detectable by a chest radiograph [35]. CT Chest Examples of airway conditions that may result in chronic dyspnea and can be accurately diagnosed by CT include stenoses, tumors, and end-expiratory airway collapse/tracheobronchomalacia, with strong correlations when compared with bronchoscopy [36,37]. For the last condition, expiratory images are required for diagnosis. Both dynamic airway imaging and static forced expiratory imaging are able to accurately characterize airway collapse when compared with bronchoscopy [38,39]. It has been shown that the degree of expiratory collapse is greater on dynamic studies compared to static forced expiratory images, although the clinical importance of this observation remains unclear [39,40]. Forced expiratory measurements show good reproducibility in healthy volunteers [41]. Volume acquisition of the airways allows for the production of 2-D and 3-D reformations that can better delineate the extent of abnormalities, while perspective volume rendering (virtual bronchoscopy) may be helpful in preprocedural planning. MRI Chest There are limited data supporting the use of MRI for the central airways in adult populations [42,43]. Some data supporting the use of MRI in pediatric populations [44,45] may be applicable in adults. FDG-PET/CT Skull Base to Mid-Thigh FDG-PET/CT has a supplemental role in the staging of tracheal neoplasms; however, there are no data to support its use in other tracheal conditions.

Chronic Dyspnea Noncardiovascular Origin. Variant 3: Chronic dyspnea. Suspected central airways disease. Initial imaging. Radiography Chest Chest radiographs have the potential to identify conditions of the trachea, with accuracy dependent on the condition to be identified. Compared to CT, radiographs have an accuracy of 89% [34]. It should be noted that radiographic findings may be normal or nonspecific. In a single-institution retrospective study of tracheal neoplasms, <50% were directly detectable by a chest radiograph [35]. CT Chest Examples of airway conditions that may result in chronic dyspnea and can be accurately diagnosed by CT include stenoses, tumors, and end-expiratory airway collapse/tracheobronchomalacia, with strong correlations when compared with bronchoscopy [36,37]. For the last condition, expiratory images are required for diagnosis. Both dynamic airway imaging and static forced expiratory imaging are able to accurately characterize airway collapse when compared with bronchoscopy [38,39]. It has been shown that the degree of expiratory collapse is greater on dynamic studies compared to static forced expiratory images, although the clinical importance of this observation remains unclear [39,40]. Forced expiratory measurements show good reproducibility in healthy volunteers [41]. Volume acquisition of the airways allows for the production of 2-D and 3-D reformations that can better delineate the extent of abnormalities, while perspective volume rendering (virtual bronchoscopy) may be helpful in preprocedural planning. MRI Chest There are limited data supporting the use of MRI for the central airways in adult populations [42,43]. Some data supporting the use of MRI in pediatric populations [44,45] may be applicable in adults. FDG-PET/CT Skull Base to Mid-Thigh FDG-PET/CT has a supplemental role in the staging of tracheal neoplasms; however, there are no data to support its use in other tracheal conditions.

69448

acrac_69448_5

Chronic Dyspnea Noncardiovascular Origin

US Chest One small study has shown that measurements obtained from US imaging of the extrathoracic trachea correlate well with MRI [46]; however, a transthoracic US technique is limited by its inability to evaluate the entire tracheobronchial tree. Chronic Dyspnea-Noncardiovascular Origin Variant 4: Chronic dyspnea. Suspected interstitial lung disease. Initial imaging. Radiography Chest The chest radiograph may be abnormal in diffuse ILD; however, studies documenting the sensitivity of chest radiographs predate the widespread use of CT [47]. A normal chest radiograph in the setting of suspected ILD does not exclude the possibility of clinically important ILD. In subjects with diseases that predispose them to ILD (eg, connective tissue disease), it is reasonable to consider CT rather than radiography as the primary screening modality. CT Chest CT is currently the preferred imaging method for evaluating ILD [48]. CT protocols should be tailored to the clinical setting and may include expiratory or prone imaging. Good correlation has been reported between extent of disease on CT and severity of dyspnea [49-53]. CT findings are often sufficient to permit either a limited differential or confident diagnosis; the latter occurs particularly in the diagnosis of usual interstitial pneumonia [54-57], although the diagnostic yield improves with multidisciplinary discussion [58,59]. There is moderate agreement across individuals in the rating of honeycomb change [60]. The presence and extent of honeycomb change and other imaging features of ILD may serve as important prognostic variables [61,62]. MRI Chest MRI does not currently have an established clinical role in the evaluation of ILD, although small studies have shown good concordance with CT [63-65]. In general, MRI does not yet display the same level of parenchymal detail that is available with CT.

Chronic Dyspnea Noncardiovascular Origin. US Chest One small study has shown that measurements obtained from US imaging of the extrathoracic trachea correlate well with MRI [46]; however, a transthoracic US technique is limited by its inability to evaluate the entire tracheobronchial tree. Chronic Dyspnea-Noncardiovascular Origin Variant 4: Chronic dyspnea. Suspected interstitial lung disease. Initial imaging. Radiography Chest The chest radiograph may be abnormal in diffuse ILD; however, studies documenting the sensitivity of chest radiographs predate the widespread use of CT [47]. A normal chest radiograph in the setting of suspected ILD does not exclude the possibility of clinically important ILD. In subjects with diseases that predispose them to ILD (eg, connective tissue disease), it is reasonable to consider CT rather than radiography as the primary screening modality. CT Chest CT is currently the preferred imaging method for evaluating ILD [48]. CT protocols should be tailored to the clinical setting and may include expiratory or prone imaging. Good correlation has been reported between extent of disease on CT and severity of dyspnea [49-53]. CT findings are often sufficient to permit either a limited differential or confident diagnosis; the latter occurs particularly in the diagnosis of usual interstitial pneumonia [54-57], although the diagnostic yield improves with multidisciplinary discussion [58,59]. There is moderate agreement across individuals in the rating of honeycomb change [60]. The presence and extent of honeycomb change and other imaging features of ILD may serve as important prognostic variables [61,62]. MRI Chest MRI does not currently have an established clinical role in the evaluation of ILD, although small studies have shown good concordance with CT [63-65]. In general, MRI does not yet display the same level of parenchymal detail that is available with CT.

69448

acrac_69448_6

Chronic Dyspnea Noncardiovascular Origin

A specific advantage of MRI may exist when a single examination is desired for the evaluation of both ILD and its effect on the cardiovascular system [66]. FDG-PET/CT Skull Base to Mid-Thigh FDG-PET/CT may have a secondary role in ILD evaluation. It can be used as a marker of disease extent and severity in sarcoidosis [67], reveal inflammatory activity before morphological changes are demonstrated on CT [68], and assist in follow-up and the monitoring of treatment response [10]. Some studies show that the degree of FDG activity correlates with severity and prognosis in ILD [69-71]. US Chest US has been evaluated as a potential ILD screening tool in high-risk populations. In scleroderma, US was concordant with CT in 83% of patients and demonstrated high sensitivity [72]. It is being used in some centers to detect chronic ILD [73,74] and is emerging as a monitoring tool [75]. Variant 5: Chronic dyspnea. Suspected disease of the pleura or chest wall. Initial imaging. Radiography Chest Pleural effusion is often diagnosed by a chest radiograph, and volume can reasonably be estimated [76]. A radiograph is somewhat limited in its ability to determine the exact location of an abnormality, whether parenchymal, pleural, or extrapleural. A chest radiograph may reveal structural abnormalities of the sternum, ribs, and thoracic spine that may predispose toward dyspnea. CT Chest CT is superior to radiographs in detecting and characterizing pleural disease, differentiating it from parenchymal and chest wall disease, and determining the extent of involvement [77]. CT is somewhat limited in its ability to differentiate causes of pleural effusion, although the presence of pleural thickening or enhancement may help document complex exudative and malignant effusions [78,79]. MRI Chest MRI may provide improved characterization and assessment of the extent of pleural and chest wall abnormalities compared to CT.

Chronic Dyspnea Noncardiovascular Origin. A specific advantage of MRI may exist when a single examination is desired for the evaluation of both ILD and its effect on the cardiovascular system [66]. FDG-PET/CT Skull Base to Mid-Thigh FDG-PET/CT may have a secondary role in ILD evaluation. It can be used as a marker of disease extent and severity in sarcoidosis [67], reveal inflammatory activity before morphological changes are demonstrated on CT [68], and assist in follow-up and the monitoring of treatment response [10]. Some studies show that the degree of FDG activity correlates with severity and prognosis in ILD [69-71]. US Chest US has been evaluated as a potential ILD screening tool in high-risk populations. In scleroderma, US was concordant with CT in 83% of patients and demonstrated high sensitivity [72]. It is being used in some centers to detect chronic ILD [73,74] and is emerging as a monitoring tool [75]. Variant 5: Chronic dyspnea. Suspected disease of the pleura or chest wall. Initial imaging. Radiography Chest Pleural effusion is often diagnosed by a chest radiograph, and volume can reasonably be estimated [76]. A radiograph is somewhat limited in its ability to determine the exact location of an abnormality, whether parenchymal, pleural, or extrapleural. A chest radiograph may reveal structural abnormalities of the sternum, ribs, and thoracic spine that may predispose toward dyspnea. CT Chest CT is superior to radiographs in detecting and characterizing pleural disease, differentiating it from parenchymal and chest wall disease, and determining the extent of involvement [77]. CT is somewhat limited in its ability to differentiate causes of pleural effusion, although the presence of pleural thickening or enhancement may help document complex exudative and malignant effusions [78,79]. MRI Chest MRI may provide improved characterization and assessment of the extent of pleural and chest wall abnormalities compared to CT.

69448

acrac_69448_7

Chronic Dyspnea Noncardiovascular Origin

MRI can help distinguish components of complex fluid collections, including septations [80], and is thought to be slightly better at distinguishing benign from malignant pleural thickening [81]. Improved soft-tissue contrast allows for better demonstration of soft-tissue relationships, which can facilitate the assessment of invasion and neurovascular encasement. Small studies have shown that MRI is capable of providing diagnostic images to guide surgical chest wall reconstruction [82]. There is extensive supportive literature in pediatric populations surrounding the detection and management of pectus excavatum. FDG-PET/CT Skull Base to Mid-Thigh FDG-PET/CT remains a secondary test that may be used in the staging of mesothelioma and pleural metastatic disease. Chronic Dyspnea-Noncardiovascular Origin US Chest US can complement the imaging evaluation of several abnormalities. US has an established role in pleural effusion, including detection, differentiation from lung disease, characterization, and guidance of intervention. US may be more efficacious than chest radiography and CT at detecting internal septations in complex pleural effusions [83]. Pleural thickening, plaques, and masses may be identifiable on US, although US is not recommended in their workup. US is advantageous in the bedside diagnosis of pneumothorax and is most often used in acute assessment [84]. Variant 6: Chronic dyspnea. Suspected diaphragm dysfunction. Initial imaging. Radiography Chest A static chest radiograph is useful to assess the relative position of the diaphragm and its effect on lung volumes and can provide clues to diaphragm paralysis compared to a fluoroscopic reference standard [85]. Fluoroscopy Chest With fluoroscopic visualization, more accurate assessment of diaphragmatic motion can be made [86,87].

Chronic Dyspnea Noncardiovascular Origin. MRI can help distinguish components of complex fluid collections, including septations [80], and is thought to be slightly better at distinguishing benign from malignant pleural thickening [81]. Improved soft-tissue contrast allows for better demonstration of soft-tissue relationships, which can facilitate the assessment of invasion and neurovascular encasement. Small studies have shown that MRI is capable of providing diagnostic images to guide surgical chest wall reconstruction [82]. There is extensive supportive literature in pediatric populations surrounding the detection and management of pectus excavatum. FDG-PET/CT Skull Base to Mid-Thigh FDG-PET/CT remains a secondary test that may be used in the staging of mesothelioma and pleural metastatic disease. Chronic Dyspnea-Noncardiovascular Origin US Chest US can complement the imaging evaluation of several abnormalities. US has an established role in pleural effusion, including detection, differentiation from lung disease, characterization, and guidance of intervention. US may be more efficacious than chest radiography and CT at detecting internal septations in complex pleural effusions [83]. Pleural thickening, plaques, and masses may be identifiable on US, although US is not recommended in their workup. US is advantageous in the bedside diagnosis of pneumothorax and is most often used in acute assessment [84]. Variant 6: Chronic dyspnea. Suspected diaphragm dysfunction. Initial imaging. Radiography Chest A static chest radiograph is useful to assess the relative position of the diaphragm and its effect on lung volumes and can provide clues to diaphragm paralysis compared to a fluoroscopic reference standard [85]. Fluoroscopy Chest With fluoroscopic visualization, more accurate assessment of diaphragmatic motion can be made [86,87].

69448

acrac_69448_8

Chronic Dyspnea Noncardiovascular Origin

CT Chest While CT can document the position of the diaphragm with multiplanar imaging and in theory can provide dynamic information, there are no data to support its use in the analysis of diaphragmatic dysfunction. MRI Chest Although not widely practiced, cine dynamic MRI sequences allow for the direct visualization of diaphragm motion [88]. This can result in comprehensive analysis of both the diaphragm and chest wall muscle movement in neuromuscular diseases [89]. US Chest US findings have been found to be concordant with fluoroscopic imaging of diaphragm motion, with reproducible results [90]. Diaphragmatic excursion amplitude, thickness, and contraction can be evaluated, and paralysis may be identified as paradoxical movement during respiration [91]. There is high sensitivity and specificity for the diagnosis of neuromuscular disorders of the diaphragm [92-95]. The extent of diaphragm motion in various conditions, including neuromuscular diseases, COPD, and ILD, correlates with respiratory symptoms and lung function [96-100]. Summary of Recommendations Variant 1: For patients with chronic dyspnea of unclear etiology, it is usually appropriate to initially evaluate with chest radiography, which may reveal a wide variety of abnormalities and guide further imaging decisions. Variant 2: The appropriate initial imaging study for patients with chronic dyspnea with suspected COPD is usually a chest radiograph, which can evaluate for comorbidities, complications, and alternative diagnoses. Variant 3: A chest radiograph is usually appropriate for the initial imaging of patients with chronic dyspnea and suspected central airways disease. Alternatively, CT without IV contrast is also usually appropriate, particularly for the detection of airway collapse, stenosis, or tumor. Variant 4: CT without IV contrast is usually appropriate for the initial imaging of patients with chronic dyspnea and suspected ILD, especially if the patient has a disease that predisposes to ILD.

Chronic Dyspnea Noncardiovascular Origin. CT Chest While CT can document the position of the diaphragm with multiplanar imaging and in theory can provide dynamic information, there are no data to support its use in the analysis of diaphragmatic dysfunction. MRI Chest Although not widely practiced, cine dynamic MRI sequences allow for the direct visualization of diaphragm motion [88]. This can result in comprehensive analysis of both the diaphragm and chest wall muscle movement in neuromuscular diseases [89]. US Chest US findings have been found to be concordant with fluoroscopic imaging of diaphragm motion, with reproducible results [90]. Diaphragmatic excursion amplitude, thickness, and contraction can be evaluated, and paralysis may be identified as paradoxical movement during respiration [91]. There is high sensitivity and specificity for the diagnosis of neuromuscular disorders of the diaphragm [92-95]. The extent of diaphragm motion in various conditions, including neuromuscular diseases, COPD, and ILD, correlates with respiratory symptoms and lung function [96-100]. Summary of Recommendations Variant 1: For patients with chronic dyspnea of unclear etiology, it is usually appropriate to initially evaluate with chest radiography, which may reveal a wide variety of abnormalities and guide further imaging decisions. Variant 2: The appropriate initial imaging study for patients with chronic dyspnea with suspected COPD is usually a chest radiograph, which can evaluate for comorbidities, complications, and alternative diagnoses. Variant 3: A chest radiograph is usually appropriate for the initial imaging of patients with chronic dyspnea and suspected central airways disease. Alternatively, CT without IV contrast is also usually appropriate, particularly for the detection of airway collapse, stenosis, or tumor. Variant 4: CT without IV contrast is usually appropriate for the initial imaging of patients with chronic dyspnea and suspected ILD, especially if the patient has a disease that predisposes to ILD.

69448

acrac_3102389_0

Congenital or Acquired Heart Disease

Introduction/Background Congenital and acquired pediatric heart disease is a large and diverse field with an overall prevalence estimated at 6 to 13 per 1,000 live births [1,2]. Congenital heart disease (CHD) can be broadly divided into acyanotic and cyanotic conditions. The 3 most common conditions are all acyanotic; bicuspid aortic valve, ventricular septal defects (VSD), and atrial septal defects. Common acquired cardiovascular conditions in children include aortopathy, cardiomyopathy, myocarditis, and vasculitis. Advanced imaging plays an important complementary role to transthoracic echocardiography (TTE) in the initial evaluation of congenital and acquired cardiovascular disease in children. Advances in treatment [2,3] have resulted in much longer survival of patients with CHD [4]. This longer survival has resulted in postsurgical patients often requiring imaging follow-up to look for secondary complications of corrective procedures like ventricular dysfunction, valvular dysfunction, and secondary vascular compromise. This document covers variants representing some of the most common indications for advanced imaging of childhood onset cardiovascular disease. 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. 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] Congenital or Acquired Heart Disease

Congenital or Acquired Heart Disease. Introduction/Background Congenital and acquired pediatric heart disease is a large and diverse field with an overall prevalence estimated at 6 to 13 per 1,000 live births [1,2]. Congenital heart disease (CHD) can be broadly divided into acyanotic and cyanotic conditions. The 3 most common conditions are all acyanotic; bicuspid aortic valve, ventricular septal defects (VSD), and atrial septal defects. Common acquired cardiovascular conditions in children include aortopathy, cardiomyopathy, myocarditis, and vasculitis. Advanced imaging plays an important complementary role to transthoracic echocardiography (TTE) in the initial evaluation of congenital and acquired cardiovascular disease in children. Advances in treatment [2,3] have resulted in much longer survival of patients with CHD [4]. This longer survival has resulted in postsurgical patients often requiring imaging follow-up to look for secondary complications of corrective procedures like ventricular dysfunction, valvular dysfunction, and secondary vascular compromise. This document covers variants representing some of the most common indications for advanced imaging of childhood onset cardiovascular disease. 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. 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] Congenital or Acquired Heart Disease

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Congenital or Acquired Heart Disease

Arteriography Coronary with Ventriculography Catheter angiography is a useful modality for the evaluation of the coronary arteries and measurement of atrial and ventricular pressure. It provides direct measurements of RVOT gradients, dynamic assessment of regurgitant flow, and hemodynamic assessment of diastolic dysfunction [9]. Coronary angiography is performed in patients with suspected anomalous coronary artery to delineate the course of the coronary artery before interventions in the RVOT [10,11]. This could be important in the setting of percutaneous intervention, because one concern is coronary artery compression with inflation of a balloon-expandable stent in the RVOT when performing PVR percutaneously. Arteriography Pulmonary Cardiac catheterization is performed in patients only when alternative measures cannot accurately assess the RV and pulmonary artery anatomy or hemodynamics noninvasively. However, angiographic evaluation of PR severity is complicated by the fact that catheter position across the PV may influence the angiographic severity. It allows for simultaneous catheter-guided therapeutic interventions such as pulmonary artery balloon dilatation and stent placement and PVR [12]. CT Heart Function and Morphology A common deficiency of TTE imaging in repaired TOF is imaging of the branch pulmonary arteries. Multidetector CT provides accurate assessment of the anatomy of the branch pulmonary arteries, including within stented segments. It provides detailed anatomic evaluation of the heart and RVOT as well as other vascular abnormalities, such as pulmonary artery aneurysms or pseudoaneurysms, associated coronary anomalies, or aortic dilation [13,14]. Performing electrocardiogram (ECG) gating permits dynamic assessment of the RVOT for percutaneous pulmonary valve planning, and measurement of RV and left ventricular (LV) volume and function.

Congenital or Acquired Heart Disease. Arteriography Coronary with Ventriculography Catheter angiography is a useful modality for the evaluation of the coronary arteries and measurement of atrial and ventricular pressure. It provides direct measurements of RVOT gradients, dynamic assessment of regurgitant flow, and hemodynamic assessment of diastolic dysfunction [9]. Coronary angiography is performed in patients with suspected anomalous coronary artery to delineate the course of the coronary artery before interventions in the RVOT [10,11]. This could be important in the setting of percutaneous intervention, because one concern is coronary artery compression with inflation of a balloon-expandable stent in the RVOT when performing PVR percutaneously. Arteriography Pulmonary Cardiac catheterization is performed in patients only when alternative measures cannot accurately assess the RV and pulmonary artery anatomy or hemodynamics noninvasively. However, angiographic evaluation of PR severity is complicated by the fact that catheter position across the PV may influence the angiographic severity. It allows for simultaneous catheter-guided therapeutic interventions such as pulmonary artery balloon dilatation and stent placement and PVR [12]. CT Heart Function and Morphology A common deficiency of TTE imaging in repaired TOF is imaging of the branch pulmonary arteries. Multidetector CT provides accurate assessment of the anatomy of the branch pulmonary arteries, including within stented segments. It provides detailed anatomic evaluation of the heart and RVOT as well as other vascular abnormalities, such as pulmonary artery aneurysms or pseudoaneurysms, associated coronary anomalies, or aortic dilation [13,14]. Performing electrocardiogram (ECG) gating permits dynamic assessment of the RVOT for percutaneous pulmonary valve planning, and measurement of RV and left ventricular (LV) volume and function.

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Congenital or Acquired Heart Disease

Multiplanar reformats allow for precise measurement of the cross-sectional area of the RVOT and valvular annulus, which are essential for selection of the appropriate prosthetic valve, and to screen for conduit calcification and kinking. before repeat surgery to replace the conduit or valve, CT is also helpful to determine safety of sternal re-entry. CTA Chest CTA without ECG gating or with prospective ECG gating may be used in the setting of TOF to avoid the need for sedation for morphological assessment of the branch pulmonary arteries, including within stented segments. It is also helpful to screen for right ventricle to pulmonary artery conduit calcification and stenosis and to determine safety of sternal re-entry before surgery. Congenital or Acquired Heart Disease CTA Coronary Arteries CTA technique can be used to study accurate coronary artery anatomy and exclude anomalous coronary artery crossing the RVOT before RVOT intervention or reoperation. Particularly, the relationship of the left or right coronary artery to the pulmonary outflow tract and pulmonary valve is important to assess because this may be compressed during percutaneous valve placement, conduit dilation, or sternal re-entry. FDG-PET/CT Heart There is no relevant literature to support the use of fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG)-PET/CT heart in the evaluation of repaired TOF. MRA Abdomen There is no relevant literature to support the use of MR angiography (MRA) abdomen in the evaluation of repaired TOF. MRA Chest MRA of the chest is routinely performed along with MRI heart for function and morphology for delineation of the extracardiac vasculature, including the branch pulmonary arteries, aorta, and remaining mediastinal vasculature. MRA Neck There is no relevant literature to support the use of MRA neck in the evaluation of repaired TOF. MRI Heart Function with Stress There is no relevant literature to support the use of MR stress perfusion imaging in the setting of repaired TOF.

Congenital or Acquired Heart Disease. Multiplanar reformats allow for precise measurement of the cross-sectional area of the RVOT and valvular annulus, which are essential for selection of the appropriate prosthetic valve, and to screen for conduit calcification and kinking. before repeat surgery to replace the conduit or valve, CT is also helpful to determine safety of sternal re-entry. CTA Chest CTA without ECG gating or with prospective ECG gating may be used in the setting of TOF to avoid the need for sedation for morphological assessment of the branch pulmonary arteries, including within stented segments. It is also helpful to screen for right ventricle to pulmonary artery conduit calcification and stenosis and to determine safety of sternal re-entry before surgery. Congenital or Acquired Heart Disease CTA Coronary Arteries CTA technique can be used to study accurate coronary artery anatomy and exclude anomalous coronary artery crossing the RVOT before RVOT intervention or reoperation. Particularly, the relationship of the left or right coronary artery to the pulmonary outflow tract and pulmonary valve is important to assess because this may be compressed during percutaneous valve placement, conduit dilation, or sternal re-entry. FDG-PET/CT Heart There is no relevant literature to support the use of fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG)-PET/CT heart in the evaluation of repaired TOF. MRA Abdomen There is no relevant literature to support the use of MR angiography (MRA) abdomen in the evaluation of repaired TOF. MRA Chest MRA of the chest is routinely performed along with MRI heart for function and morphology for delineation of the extracardiac vasculature, including the branch pulmonary arteries, aorta, and remaining mediastinal vasculature. MRA Neck There is no relevant literature to support the use of MRA neck in the evaluation of repaired TOF. MRI Heart Function with Stress There is no relevant literature to support the use of MR stress perfusion imaging in the setting of repaired TOF.

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Congenital or Acquired Heart Disease

Radiography Chest The chest radiograph in TOF patients with severe PR often demonstrates increased cardiothoracic ratio on frontal view and retrosternal fullness on the lateral view due to cardiomegaly secondary to RV volume overload. The chest radiograph may also demonstrate dilated pulmonary trunk and may demonstrate dilatation of the ascending aorta [9]. In the posttreatment setting, radiography is essential to monitor location and integrity of stents in the pulmonary arteries, screen for RVOT pseudoaneurysm after conduit placement, and screen for asymmetry in the size and branching pattern of the parenchymal pulmonary arteries, which may indicate the presence of proximal vessel hypoplasia or stenosis. Perfusion Scan Lung The use of pulmonary perfusion scintigraphy allows for the assessment of differential pulmonary blood flow in patients with TOF and branch pulmonary artery stenosis or hypoplasia [12]. SPECT/CT MPI Rest and Stress Radionuclide angiography may be performed to assess LV function but has been replaced by MRI in this setting. Its use to assess RV function is limited by the confounding effect of counts from other chambers. In addition, its resolution is poor compared with other imaging methods and, therefore, has been of limited use in this setting. Congenital or Acquired Heart Disease US Echocardiography Transesophageal Transesophageal echocardiography (TEE) is considered a useful technique for intraoperative assessment of adequacy of outflow tract repair in terms of ruling out any residual obstruction or valve regurgitation as a consequence of surgery. TEE offers the advantages of permitting visualization of the operative procedure in real time and providing guidance for the surgeon [6,18] . The routine use of TEE during follow-up after surgery for patients with TOF is not established.

Congenital or Acquired Heart Disease. Radiography Chest The chest radiograph in TOF patients with severe PR often demonstrates increased cardiothoracic ratio on frontal view and retrosternal fullness on the lateral view due to cardiomegaly secondary to RV volume overload. The chest radiograph may also demonstrate dilated pulmonary trunk and may demonstrate dilatation of the ascending aorta [9]. In the posttreatment setting, radiography is essential to monitor location and integrity of stents in the pulmonary arteries, screen for RVOT pseudoaneurysm after conduit placement, and screen for asymmetry in the size and branching pattern of the parenchymal pulmonary arteries, which may indicate the presence of proximal vessel hypoplasia or stenosis. Perfusion Scan Lung The use of pulmonary perfusion scintigraphy allows for the assessment of differential pulmonary blood flow in patients with TOF and branch pulmonary artery stenosis or hypoplasia [12]. SPECT/CT MPI Rest and Stress Radionuclide angiography may be performed to assess LV function but has been replaced by MRI in this setting. Its use to assess RV function is limited by the confounding effect of counts from other chambers. In addition, its resolution is poor compared with other imaging methods and, therefore, has been of limited use in this setting. Congenital or Acquired Heart Disease US Echocardiography Transesophageal Transesophageal echocardiography (TEE) is considered a useful technique for intraoperative assessment of adequacy of outflow tract repair in terms of ruling out any residual obstruction or valve regurgitation as a consequence of surgery. TEE offers the advantages of permitting visualization of the operative procedure in real time and providing guidance for the surgeon [6,18] . The routine use of TEE during follow-up after surgery for patients with TOF is not established.

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