Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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]. 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.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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 PCAs

Suspected Spine Trauma

Suspected Spine Trauma PCAs. Suspected Spine Trauma


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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

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].


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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

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.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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 PCAs

Suspected Spine Trauma


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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]. 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.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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.


Suspected Spine Trauma PCAs

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]. 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. 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].


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. MRA Neck There is no role for MRA in the initial assessment of patients with suspected cervical spine injury.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. Arteriography Cervicocerebral There is no role for arteriography in the initial assessment of patients with suspected cervical spine injury.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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. 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 PCAs

Suspected Spine Trauma PCAs. 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.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. MRA Neck There is no role for MRA in the evaluation of suspected traumatic cervical myelopathy or radiculopathy [59]. If there is concern for arterial dissection that is due to the mechanism of injury, please refer to Variant 5.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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]. 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 PCAs

Suspected Spine Trauma

Suspected Spine Trauma PCAs. Suspected Spine Trauma


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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]. 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 PCAs

Suspected Spine Trauma


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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. 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].


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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

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.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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 PCAs

Suspected Spine Trauma PCAs. patients with ligament injury identified on MRI had an abnormality identified on flexion-extension radiographs. Furthermore, flexion-extension radiographs carry the real danger of producing neurologic injury.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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].


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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

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.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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 PCAs

Suspected Spine Trauma PCAs. 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].


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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. 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.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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].


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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. 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 PCAs

Suspected Spine Trauma

Suspected Spine Trauma PCAs. Suspected Spine Trauma


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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].


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. MRI Cervical Spine MRI is the gold standard for imaging diagnosis of traumatic soft-tissue injuries of the neck. 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.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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].


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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 PCAs

Suspected Spine Trauma


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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

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].


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. CT Myelography Thoracic and Lumbar Spine There is no role for CT myelography in the initial assessment of thoracolumbar spine injury.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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 PCAs

Suspected Spine Trauma PCAs. Variant 10: Age greater than or equal to 16 years. Acute thoracic or lumbar spine injury detected on radiographs or noncontrast CT. 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.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. 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

Suspected Spine Trauma PCAs. For additional information on the Appropriateness Criteria methodology and other supporting documents go to www.acr.org/ac.


Suspected Spine Trauma PCAs

Suspected Spine Trauma PCAs. Appropriateness Category Names and Definitions Relative Radiation Level Information Potential adverse health effects associated with radiation exposure are an important factor to consider when selecting the appropriate imaging procedure. Because there is a wide range of radiation exposures associated with different diagnostic procedures, a relative radiation level (RRL) indication has been included for each imaging examination. The RRLs are based on effective dose, which is a radiation dose quantity that is used to estimate population total radiation risk associated with an imaging procedure. Patients in the pediatric age group are at inherently higher risk from exposure, because of both organ sensitivity and longer life expectancy (relevant to the long latency that appears to accompany radiation exposure). For these reasons, the RRL dose estimate ranges for


Suspected Spine Trauma PCAs

Suspected Spine Trauma

Suspected Spine Trauma PCAs. Suspected Spine Trauma


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. 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].


Chest Pain Possible Acute Coronary Syndrome PCAs. 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


Chest Pain Possible Acute Coronary Syndrome 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.


Chest Pain Possible Acute Coronary Syndrome PCAs. Reprint requests to: publications@acr.org


Chest Pain Possible Acute Coronary Syndrome PCAs. 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]. 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].


Chest Pain Possible Acute Coronary Syndrome PCAs. 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.


Chest Pain Possible Acute Coronary Syndrome PCAs. 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.


Chest Pain Possible Acute Coronary Syndrome PCAs. 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].


Chest Pain Possible Acute Coronary Syndrome PCAs. 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]. 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 PCAs. Chest Pain-Possible Acute Coronary Syndrome


Chest Pain Possible Acute Coronary Syndrome PCAs. 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].


Chest Pain Possible Acute Coronary Syndrome PCAs. 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].


Chest Pain Possible Acute Coronary Syndrome PCAs. 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]. 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.


Chest Pain Possible Acute Coronary Syndrome PCAs. 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].


Chest Pain Possible Acute Coronary Syndrome PCAs. 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]. 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 PCAs. 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].


Chest Pain Possible Acute Coronary Syndrome PCAs. 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].


Chest Pain Possible Acute Coronary Syndrome PCAs. 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. 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.


Chest Pain Possible Acute Coronary Syndrome PCAs. 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. 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 PCAs. 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.


Chest Pain Possible Acute Coronary Syndrome PCAs. 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]. 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].


Chest Pain Possible Acute Coronary Syndrome PCAs. 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].


Chest Pain Possible Acute Coronary Syndrome PCAs. 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]. 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].


Chest Pain Possible Acute Coronary Syndrome PCAs. 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 PCAs. Chest Pain-Possible Acute Coronary Syndrome


Chest Pain Possible Acute Coronary Syndrome PCAs. 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]. 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.


Chest Pain Possible Acute Coronary Syndrome PCAs. CTA Coronary Arteries There is no relevant literature regarding the use of CCTA in the evaluation of ACS in high-probability patients.


Chest Pain Possible Acute Coronary Syndrome PCAs. 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].


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].


Chest Pain Possible Acute Coronary Syndrome PCAs. CT Coronary Calcium There is no relevant literature regarding the use of CT calcium scoring in the evaluation of ACS in high-probability patients.


Chest Pain Possible Acute Coronary Syndrome PCAs. MRA Coronary Arteries There is no relevant literature regarding the use of coronary MRA in the evaluation of ACS in high-risk patients.


Chest Pain Possible Acute Coronary Syndrome PCAs. 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. 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.


Chest Pain Possible Acute Coronary Syndrome PCAs. 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.


Chest Pain Possible Acute Coronary Syndrome PCAs. 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.


Chest Pain Possible Acute Coronary Syndrome PCAs. 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 PCAs. 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].


Chest Pain Possible Acute Coronary Syndrome PCAs. 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. US Echocardiography Transthoracic Rest 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]. Assessment of left ventricle function is necessary in patients with confirmed ACS in order to guide pharmacological therapies and help determine revascularization choices (eg, percutaneous coronary intervention versus bypass graft surgery). 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 a new role for resting echocardiography in the evaluation of ACS.


Chest Pain Possible Acute Coronary Syndrome PCAs. Supporting Documents Summary of Recommendations 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.


Chest Pain Possible Acute Coronary Syndrome PCAs. Chest Pain-Possible Acute Coronary Syndrome For additional information on the Appropriateness Criteria methodology and other supporting documents go to www.acr.org/ac.


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].


Hydronephrosis on Prior Imaging Unknown Cause. 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. 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


Hydronephrosis on Prior Imaging Unknown Cause. Reprint requests to: publications@acr.org


Hydronephrosis on Prior Imaging Unknown Cause. 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.


Hydronephrosis on Prior Imaging Unknown Cause. 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. 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.


Hydronephrosis on Prior Imaging Unknown Cause. 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]).


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 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.


Hydronephrosis on Prior Imaging 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 patients with asymptomatic unilateral hydronephrosis with unknown cause, and more comprehensive evaluation with CT, MRU, or renal scintigraphy is preferred.


Hydronephrosis on Prior Imaging Unknown Cause. 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. CT abdomen and pelvis without IV contrast is particularly useful when obstructive urolithiasis is a primary concern.


Hydronephrosis on Prior Imaging Unknown Cause. 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. 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.


Hydronephrosis on Prior Imaging 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.


Hydronephrosis on Prior Imaging 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.


Hydronephrosis on Prior Imaging Unknown Cause. 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 glomerular filtration rate (GFR), although it may somewhat overestimate global GFR in the setting of obstructive hydronephrosis [13].


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 unilateral hydronephrosis with unknown cause.


Hydronephrosis on Prior Imaging 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.


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 [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].


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 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.


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 unilateral hydronephrosis with unknown cause.


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.


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 asymptomatic unilateral hydronephrosis with unknown cause.


Hydronephrosis on Prior Imaging 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. Hydronephrosis on Prior Imaging-Unknown Cause


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.


Hydronephrosis on Prior Imaging Unknown Cause. 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. 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.


Hydronephrosis on Prior Imaging Unknown Cause. 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.


Hydronephrosis on Prior Imaging Unknown Cause. 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.


Hydronephrosis on Prior Imaging Unknown Cause. 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.


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 patients with asymptomatic unilateral 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 or MRU, renal scintigraphy, or US color Doppler kidneys and bladder retroperitoneal.


Hydronephrosis on Prior Imaging Unknown Cause. 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.


Hydronephrosis on Prior Imaging Unknown Cause. 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. 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.


Hydronephrosis on Prior Imaging 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 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.


Hydronephrosis on Prior Imaging Unknown Cause. 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.


Hydronephrosis on Prior Imaging 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 patients with asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney 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 bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause.


Hydronephrosis on Prior Imaging 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.


Hydronephrosis on Prior Imaging 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.


Hydronephrosis on Prior Imaging Unknown Cause. 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. 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.


Hydronephrosis on Prior Imaging 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. 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 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. 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.


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 bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause.


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 asymptomatic bilateral hydronephrosis or asymptomatic hydronephrosis in a solitary kidney with unknown cause.


Hydronephrosis on Prior Imaging 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.


Hydronephrosis on Prior Imaging Unknown Cause. 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. 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.


Hydronephrosis on Prior Imaging Unknown Cause. 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. 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.


Hydronephrosis on Prior Imaging Unknown Cause. 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. 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.


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 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.


Hydronephrosis on Prior Imaging Unknown Cause. 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.


Hydronephrosis on Prior Imaging Unknown Cause. Variant 3: Adult. Symptomatic hydronephrosis with unknown cause. Initial imaging. 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).


Hydronephrosis on Prior Imaging Unknown Cause. 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.


Hydronephrosis on Prior Imaging Unknown Cause. 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.


Hydronephrosis on Prior Imaging Unknown Cause. 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. 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.


Hydronephrosis on Prior Imaging Unknown Cause. 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. 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.


Hydronephrosis on Prior Imaging 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 patients with symptomatic 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 symptomatic hydronephrosis with unknown cause.


Hydronephrosis on Prior Imaging 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.