Low Back Pain PCAs

Low Back Pain PCAs. Subacute to chronic uncomplicated (no red flags) LBP, with or without radiculopathy, is considered a self-limiting condition responsive to medical management and physical therapy in most patients [4,6,7]. Numerous studies have shown that routine imaging provides no clinical benefit in this group [6,9] and can lead to increased health care utilization [6,17]. Radiography Lumbar Spine There is no relevant literature to support the use of radiography in the initial evaluation of patients in this group. Subacute to chronic uncomplicated (no red flags) LBP, with or without radiculopathy, is considered a self-limiting condition responsive to medical management and physical therapy in most patients [4,6,7]. Numerous studies have shown that routine imaging provides no clinical benefit in this group [6,9] and can lead to increased health care utilization [6,17]. Variant 3: Subacute or chronic low back pain with or without radiculopathy. Surgery or intervention candidate with persistent or progressive symptoms during or following 6 weeks of optimal medical management. Initial imaging. In the absence of red flags, first-line treatment for chronic LBP remains conservative therapy with both pharmacologic and nonpharmacologic (eg, exercise, remaining active) therapy [19]. However, patients presenting with subacute or chronic LBP, with or without radiculopathy, who have failed 6 weeks of conservative therapy should be imaged if they are believed to be candidates for surgery or intervention or if diagnostic uncertainty remains. The goal of imaging is to identify potential actionable pain generators that could be targeted for intervention or surgery. MRI of the lumbar spine has become the initial imaging modality of choice in these patients. MRI has excellent soft-tissue contrast and accurately depicts lumbar pathology, including disc degeneration, as well as the thecal sac and neural structures [7].


Low Back Pain PCAs

Low Back Pain PCAs. However, it is well known that many MRI abnormalities can be seen in asymptomatic individuals and that imaging patients in this category is often not beneficial [7,11,13,21]. MRI may be helpful when there is LBP with radiculopathy or signs of spinal stenosis, which suggests the presence of demonstrable nerve root compression [13]. Low Back Pain CT myelography of the lumbar spine can be useful in assessing the patency of the spinal canal/thecal sac and of the subarticular recesses and neural foramen [22]. It has safety advantages over MRI for patients who have implanted medical devices that are not MRI safe or conditional and can be useful in patients with significant artifact from metallic surgical hardware on MRI [23]. CT myelography has the disadvantage of requiring lumbar puncture for intrathecal injection of myelographic contrast [22]. Although radiography alone is not sufficient for guidance on surgical or interventional options without MRI and/or CT imaging, it can be seen as complementary. Upright radiographs provide useful functional information about axial loading. The ability to incorporate flexion and extension radiographs is essential to identify segmental motion, which is important in the surgical management of spondylolisthesis. Lateral bending images have been shown to be helpful in spinal deformity correction surgery [24,25]. CT lumbar spine without IV contrast may be useful for preoperative planning [26]. CT delineates osseous margins and aids in trajectory planning for hardware fixation. Additionally, CT lumbar spine without IV contrast can also be used to assess facets and neural foramina and is equal to MRI for predicting significant spinal stenosis and excluding cauda equina impingement [27]. Although evidence is limited, recent small studies have suggested SPECT/CT bone scan may help identify the source of LBP in some patients, particularly when related to facet arthropathy or sacroiliac joint dysfunction [28- 30].


Low Back Pain PCAs

Low Back Pain PCAs. SPECT bone scan is the reference standard for detection of radiographically occult active spondylolysis in the young patient [31]. Although the utility of discography in patients with LBP remains controversial, a systematic review by Manchikanti et al [32] provides level III evidence that lumbar discography may be useful in patients with chronic discogenic LBP. Bone Scan Whole Body with SPECT or SPECT/CT Complete Spine Structures with abnormal morphology on conventional imaging may not be the cause of LBP. Limited evidence suggests possible utility of bone scan with SPECT or SPECT/CT as a functional modality to localize the source of LBP, particularly for facet arthropathy [28-30]. A prospective study of 99 patients with LBP evaluated with SPECT/CT demonstrated >40% of scintigraphically active facet joints did not correlate to degree of facet joint degeneration on CT, using standardized grading scales [29]. A randomized double-blinded controlled study of 80 patients showed >50% pain relief in patients who received diagnostic facet or sacroiliac joint anesthetic blocks based on clinical and SPECT/CT findings compared with those who received blocks based on clinical and conventional imaging findings [28]. SPECT bone scan is the reference standard for detection of radiographically occult active spondylolysis in the young patient [31]. CT Lumbar Spine With IV Contrast There is no relevant literature to support the use of CT lumbar spine with IV contrast in the evaluation of a surgery or intervention candidate with persistent or progressive symptoms during or following 6 weeks of conservative management. CT Lumbar Spine Without and With IV Contrast There is no relevant literature to support the use of CT lumbar spine without and with IV contrast in the evaluation of a surgery or intervention candidate with persistent or progressive symptoms during or following 6 weeks of conservative management.


Low Back Pain PCAs

Low Back Pain PCAs. CT Lumbar Spine Without IV Contrast CT lumbar spine without IV contrast may be useful for preoperative planning [26]. CT delineates osseous margins and aids in trajectory planning for hardware fixation. Additionally, CT lumbar spine without IV contrast can be used to assess facets and neural foramina in patients who cannot undergo MRI and is equal to MRI for predicting significant spinal stenosis and excluding cauda equina impingement [27]. CT Myelography Lumbar Spine CT myelography of the lumbar spine can be useful in assessing the patency of the spinal canal/thecal sac and of the subarticular recesses and neural foramen [22]. It has safety advantages over MRI for patients who have implanted medical devices that are not MRI safe or conditional and can be useful in patients with significant artifact from metallic surgical hardware on MRI [23]. CT myelography has the disadvantage of requiring lumbar puncture for intrathecal injection of myelographic contrast [22]. Low Back Pain Discography and Post-Discography CT Lumbar Spine Although the utility of discography in patients with LBP remains controversial, a systematic review by Manchikanti et al [32] provides level III evidence that lumbar discography may be useful in patients with chronic discogenic LBP. FDG-PET/CT Whole Body There is no relevant literature to support the use of whole-body FDG-PET/CT in the evaluation of a surgery or intervention candidate with persistent or progressive symptoms during or following 6 weeks of conservative management [28-30]. MRI Lumbar Spine With IV Contrast MRI lumbar spine with IV contrast is not typically performed independently as an initial study, as its interpretation is most informative when correlated with standard noncontrast sequences included in MRI lumbar spine with and without IV contrast [33].


Low Back Pain PCAs

Low Back Pain PCAs. MRI Lumbar Spine Without and With IV Contrast MRI with IV contrast is typically not necessary in the evaluation of a surgical or interventional candidate with persistent or progressive symptoms during or following 6 weeks of conservative management but is sometimes useful if noncontrast MRI is nondiagnostic or indeterminate. Contrast can help distinguish residual/recurrent disc from fibrosis/scar in a postoperative patient (see Variant 5). MRI Lumbar Spine Without IV Contrast Patients presenting with subacute or chronic LBP or radiculopathy who have failed 6 weeks of conservative therapy, and with physical examination signs of nerve root irritation, should be imaged if they are believed to be candidates for surgery or intervention or if diagnostic uncertainty remains. Accurate diagnosis of disc disease can be provided by MRI [7]. Although disc abnormalities are common on MRI in asymptomatic patients, LBP with radiculopathy or clinical signs of spinal stenosis suggests the presence of demonstrable nerve root compression on MRI [13]. In a study of symptomatic patients, there was a higher prevalence of herniation. Fifty-seven percent of patients with LBP and 65% of patients with radiculopathy had disc herniation as compared with the 20% to 28% prevalence reported in the asymptomatic series [7]. Interestingly, the size and type of disc herniation and location and presence of nerve root compression were not related to patient outcome [7,34]. Kobayashi et al [35] have shown the utility of MRI in diagnosing active spondylolysis in radiographically occult spondylolysis. Radiography Lumbar Spine Although radiography alone is not sufficient for guidance on surgical or interventional options without MRI and/or CT imaging, it can be seen as complementary. Upright radiographs provide useful functional information about axial loading [36].


Low Back Pain PCAs

Low Back Pain PCAs. The ability to incorporate flexion and extension radiographs is essential to identify segmental motion, which is important in the surgical management of spondylolisthesis [24,37]. Lateral bending images have been shown to be helpful in spinal deformity correction surgery [25]. Variant 4: Low back pain with suspected cauda equina syndrome. Initial imaging. CES is rare and results from dysfunction of the sacral and lumbar nerve roots within the vertebral canal secondary to cauda equina nerve root compression, producing impairment of the bladder, bowel, or sexual function and perianal or saddle numbness. Back pain with or without radicular symptoms, weakness in the lower limbs, sensory changes or numbness in the lower limbs, or absent lower limb reflexes are other symptoms that have been described [38]. A review of physical examination findings reported by Fairbanks et al [39] found LBP as the most common physical finding in patients with the diagnosis of CES. The most common cause of CES is lumbar disc herniation at the L4-L5 and L5-S1 levels. Other etiologies include neoplasm, infection/inflammation, spinal stenosis, and hemorrhage. The imaging study of choice in the evaluation of suspected CES, multifocal deficit, or progressive neurologic deficit is MRI because of its ability to accurately depict soft-tissue pathology, assess vertebral marrow, and assess the Low Back Pain spinal canal patency. MRI lumbar spine without IV contrast is most useful in the evaluation of suspected CES, multifocal deficit, or progressive neurologic deficit because of its ability to accurately depict soft-tissue pathology, assess vertebral marrow, and assess the spinal canal patency. A prospective cohort study by Bell et al [41] recommends urgent MRI assessment in all patients who present with new-onset urinary symptoms in the context of LBP or sciatica.


Low Back Pain PCAs

Low Back Pain PCAs. Recently, a single 3-D heavily T2-weighted fat-saturated sequence protocol has been shown to be a rapid, highly sensitive tool for evaluating CES in the emergency department that can be utilized for improved efficiency and emergency department throughput [42]. Although MRI lumbar spine without IV contrast is the preferred initial study, MRI lumbar spine without and with IV contrast may be helpful to delineate etiology of CES when underlying malignancy, infection, or inflammation is clinically suspected (see Variant 7). CT myelography of the lumbar spine assesses the patency of the spinal canal/thecal sac and of the subarticular recesses and neural foramen [22]. It can be useful for surgical planning in patients with CES and in patients with significant spinal stenosis on CT lumbar spine without IV contrast. Bone Scan Whole Body with SPECT or SPECT/CT Complete Spine There is no relevant literature to support the use of bone scan with SPECT or SPECT/CT in the initial imaging of suspected CES. CT Lumbar Spine With IV Contrast There is no relevant literature to support the use of CT with IV contrast in the initial imaging of suspected CES. CT Lumbar Spine Without and With IV Contrast There is no relevant literature to support the use of CT without and with IV contrast in the initial imaging of suspected CES. CT Myelography Lumbar Spine CT myelography of the lumbar spine assess the patency of the spinal canal/thecal sac and of the subarticular recesses and neural foramen [22]. It can be useful for surgical planning in patients with CES. This modality has the disadvantage of lumbar puncture and injection of intrathecal contrast [22]. Discography and Post-Discography CT Lumbar Spine There is no relevant literature to support the use of discography and post-discography CT lumbar spine in the initial imaging of suspected CES. FDG-PET/CT Whole Body There is no relevant literature to support the use of whole-body FDG-PET/CT in the initial imaging of suspected CES.


Low Back Pain PCAs

Low Back Pain PCAs. MRI Lumbar Spine With IV Contrast MRI lumbar spine with IV contrast is not typically performed independently as an initial study, as its interpretation is most informative when correlated with standard noncontrast sequences included in MRI lumbar spine with and without IV contrast [33]. Low Back Pain MRI Lumbar Spine Without and With IV Contrast Although MRI lumbar spine without IV contrast is the preferred initial study, MRI lumbar spine without and with IV contrast may be helpful to delineate etiology of CES when clinical suspicion of underlying malignancy, infection, or inflammation (see Variant 7). MRI Lumbar Spine Without IV Contrast MRI lumbar spine without IV contrast is most useful in the evaluation of suspected CES, multifocal deficit, or progressive neurologic deficit because of its ability to accurately depict soft-tissue pathology, assess vertebral marrow, and assess the spinal canal patency. A prospective cohort study by Bell et al [41] recommends urgent MRI assessment in all patients who present with new-onset urinary symptoms in the context of LBP or sciatica. Recently, a single 3-D heavily T2-weighted fat-saturated sequence protocol has been shown to be a rapid, highly sensitive tool for evaluating CES in the emergency department that can be utilized for improved efficiency and emergency department throughput [42]. Radiography Lumbar Spine There is no relevant literature to support the use of radiography in the initial imaging of suspected CES. Variant 5: Low back pain with history of prior lumbar surgery and with or without radiculopathy. New or progressing symptoms or clinical findings. Initial imaging. There are many causes of back pain following surgery. Some of the more frequent etiologies diagnosed with imaging include free disc or bone fragments, postoperative scarring, failure of bone graft for fusion, and recurrent disc protrusion.


Low Back Pain PCAs

Low Back Pain PCAs. MRI lumbar spine without and with IV contrast is useful, as it accurately distinguishes recurrent or residual disc herniations from scar, and can evaluate for nerve root compression or arachnoiditis in patients with new or progressive symptoms and previous lumbar surgery [43]. It can also help identify and evaluate extent of infection. CT lumbar spine without IV contrast can be helpful in assessing osseous fusion. CT can detect potentially painful hardware failure including prosthetic loosening, malalignment, or metallic fracture [44]. Additionally, CT lumbar spine without IV contrast is equal to MRI for predicting significant spinal stenosis and excluding cauda equina impingement [27]. The addition of IV contrast is not necessary to evaluate bony fusion and hardware but may be useful to assess for epidural abscess in patients for this clinical scenario [45-47]. CT myelography of the lumbar spine can be useful in assessing the patency of the spinal canal/thecal sac and of the subarticular recesses and neural foramen [22]. It has safety advantages over MRI for patients who have implanted medical devices that are not MRI safe or conditional and can be useful in patients with significant artifact from metallic surgical hardware on MRI [23]. CT myelography is occasionally more accurate in diagnosing nerve root compression in the lateral recess [48,49] but has the disadvantages of requiring lumbar puncture for intrathecal injection of myelographic contrast[22]. In patients in whom anatomy is distorted secondary to artifacts from surgical hardware, CT myelography lumbar spine study is complementary to MRI and is occasionally more accurate in diagnosing nerve root compression in the lateral recess [48,49], but it suffers the disadvantage of requiring lumbar puncture and intrathecal contrast injection [22]. Radiography is complementary to MRI and/or CT imaging and is helpful to evaluate alignment and hardware integrity in patients with new or progressing symptoms and previous lumbar fusion.


Low Back Pain PCAs

Low Back Pain PCAs. Upright radiographs provide useful functional information about axial loading. Flexion and extension radiographs can be used to look for abnormal motion/increased dynamic mobility [50]. SPECT or SPECT/CT are not the initial imaging modality but may be an adjunct in cases of painful pseudoarthrosis or periprosthetic loosening in patients with previous lumbar fusion [51-54]. Bone Scan Whole Body with SPECT or SPECT/CT Complete Spine SPECT or SPECT/CT are not the initial imaging modality but may be an adjunct in cases of painful pseudoarthrosis or periprosthetic loosening in patients with previous lumbar fusion [51-54]. CT Lumbar Spine With IV Contrast CT lumbar spine with IV contrast to is not necessary to evaluate bony fusion and hardware but may be useful to assess for epidural abscess in patients for this clinical scenario and for patients with suspected infection [45-47]. Low Back Pain CT Lumbar Spine Without and With IV Contrast CT lumbar spine without and with IV contrast is not typically performed as there is no diagnostic advantage to performing a single study with or without IV contrast. CT Lumbar Spine Without IV Contrast CT lumbar spine without IV contrast can be helpful in assessing osseous fusion. CT can detect potentially painful hardware failure, including prosthetic loosening, malalignment, or metallic fracture [44]. Additionally, CT lumbar spine without IV contrast is equal to MRI for predicting significant spinal stenosis and excluding cauda equina impingement [27]. CT Myelography Lumbar Spine CT myelography of the lumbar spine can be useful in assessing the patency of the spinal canal/thecal sac and of the subarticular recesses and neural foramen [22]. It has safety advantages over MRI for patients who have implanted medical devices that are not MRI safe or conditional and can be useful in patients with significant artifact from metallic surgical hardware on MRI [23].


Low Back Pain PCAs

Low Back Pain PCAs. CT myelography is occasionally more accurate in diagnosing nerve root compression in the lateral recess [48,49], but it has the disadvantage of requiring lumbar puncture for intrathecal injection of myelographic contrast [22]. Discography and Post-Discography CT Lumbar Spine There is no relevant literature to support the use of discography and post-discography CT lumbar spine in the evaluation of new or progressing symptoms in patients with previous lumbar surgery. FDG-PET/CT Whole Body There is no relevant literature to support the use of whole-body FDG-PET/CT in the evaluation of new or progressing symptoms in patients with previous lumbar surgery. MRI Lumbar Spine With IV Contrast MRI lumbar spine with IV contrast is not typically performed independently as an initial study, as its interpretation is most informative when correlated with standard noncontrast sequences included in MRI lumbar spine with and without IV contrast [33]. MRI Lumbar Spine Without and With IV Contrast MRI lumbar spine without and with IV contrast is useful as it accurately distinguishes recurrent or residual disc herniations from scar, and can evaluate for nerve root compression or arachnoiditis in patients with new or progressive symptoms and previous lumbar surgery [43]. It can also help identify and evaluate extent of infection. MRI Lumbar Spine Without IV Contrast MRI lumbar spine without IV contrast can be useful in this clinical scenario. It is inferior to MRI lumbar spine without and with IV contrast for evaluating extent of infection and for differentiating postoperative epidural fibrosis (scar) from residual or recurrent disc herniations [43]. Radiography Lumbar Spine Radiography is helpful to evaluate alignment and hardware integrity in patients with new or progressing symptoms and previous lumbar fusion. Upright radiographs provide useful functional information about axial loading. Flexion and extension radiographs can be used to look for abnormal motion/increased dynamic mobility [50].


Low Back Pain PCAs

Low Back Pain PCAs. Upright radiographs provide useful functional information about axial loading. Flexion and extension views can be performed to evaluate for spine stability. However, evaluation of the extent of vertebral body comminution is limited on radiography, particularly in patients with osteoporosis. CT provides a detailed analysis of fractures extending to the posterior column of the vertebra or for evaluating the integrity of pedicles and the posterior cortex. It has been shown to be equal to MRI for predicting significant spinal stenosis and excluding cauda equina impingement [27]. Low Back Pain CT myelography of the lumbar spine assess the patency of the spinal canal/thecal sac and of the subarticular recesses and neural foramen [22]. It can be useful in patients with osteoporotic fracture with neurologic deficit. This modality has the disadvantage of lumbar puncture and injection of intrathecal contrast [22]. Bone scan with SPECT/CT is usually not used for initial imaging but can be useful for radiographically occult fractures and can be used to evaluate acuity of vertebral fracture. [59]. Whole-body FDG-PET/CT is typically not an initial imaging study, but as a follow-up study, it can help distinguish between benign and pathologic compression fractures when other imaging modalities are indeterminate [60]. Bone Scan Whole Body with SPECT or SPECT/CT Complete Spine Bone scan with SPECT/CT is usually not used for initial imaging but can be useful for radiographically occult fractures and can be used to evaluate acuity of vertebral fracture [59]. CT Lumbar Spine With IV Contrast CT with IV contrast does not provide additional information to CT lumbar spine without IV contrast for evaluation of spinal fractures and alignment. CT Lumbar Spine Without and With IV Contrast CT without and with IV contrast of the lumbar spine is not typically performed as there is no diagnostic advantage to performing a single study with or without IV contrast.


Low Back Pain PCAs

Low Back Pain PCAs. CT Myelography Lumbar Spine CT myelography of the lumbar spine assesses the patency of the spinal canal/thecal sac and of the subarticular recesses and neural foramen [22]. It can be useful in patients with osteoporotic fracture with neurologic deficit. This modality has the disadvantage of lumbar puncture and injection of intrathecal contrast [22]. Discography and Post-Discography CT Lumbar Spine There is no relevant literature to support the use of discography and post-discography CT lumbar spine in this clinical scenario. FDG-PET/CT Whole Body Whole-body FDG-PET/CT is typically not an initial imaging study, but as a follow-up study it can help distinguish between benign and pathologic compression fractures when other imaging modalities are indeterminate [60]. MRI Lumbar Spine With IV Contrast MRI lumbar spine with IV contrast is not typically performed independently as an initial study, as its interpretation is most informative when correlated with standard noncontrast sequences included in MRI lumbar spine with and without IV contrast [33]. MRI Lumbar Spine Without and With IV Contrast Although MRI lumbar spine without IV contrast is the preferred initial study, MRI lumbar spine without and with IV contrast may be helpful to delineate etiology of fracture when clinical suspicion of underlying malignancy, infection, or inflammation (see Variant 7). MRI Lumbar Spine Without IV Contrast MRI lumbar spine without IV contrast is useful in determining the acuity of a vertebral fracture, as evidenced by bone marrow edema and in demonstrating spinal canal compromise, for example from displaced or retropulsed Low Back Pain fractures. Additionally, the distinction between malignant and benign compression fractures can be assessed on MRI. The visualization of the convex posterior vertebral body border, extension into the posterior elements, and abnormal marrow signal are suggestive of pathologic fracture [58].


Low Back Pain PCAs

Low Back Pain PCAs. Radiography Lumbar Spine In patients with history of osteoporosis or steroid use, initial evaluation with radiography is useful [55]. Radiography with anteroposterior and lateral radiographs is useful for assessing LBP in patients with low suspicion of trauma or minor trauma and patients suspected of having possible vertebral compression fracture. Upright radiographs provide useful functional information about axial loading. Flexion and extension views can be performed to evaluate for spine stability. Evaluation of the extent of vertebral body comminution is limited on radiography, particularly in patients with osteoporosis. Variant 7: Low back pain with or without radiculopathy. One or more of the following: suspicion of cancer, infection, or immunosuppression. Initial imaging. A systematic review examining studies that used red flags as an indication for screening found that of all the red flags, only a history of cancer has been shown to increase the probability of finding spinal malignancy [61]. In a patient suspected of having cancer, MRI without and with IV contrast is considered superior in evaluation of localizing disease (intramedullary, intradural-extramedullary, and extradural) as well as assessing extent of the lesion. For malignant/metastatic disease, both bony/marrow involvement and neural compression from epidural tumor are visualized with high spatial resolution [62]. Although CT lumbar spine without IV contrast can be performed to evaluate osseous integrity (eg, pathologic fracture) when involved with tumor, intradural and spinal cord pathologies are poorly depicted on CT. Bone scan remains invaluable when a survey of the entire skeleton is indicated (eg, for metastatic disease); however, MRI offers greater specificity than bone scan, with comparable sensitivity and the added advantage of providing anatomic detail [63].


Low Back Pain PCAs

Low Back Pain PCAs. Although osseous destruction, as well as identifying lytic or sclerotic lesions can be detected on radiography, at least half of the bone must be eroded before there is a noticeable change on radiographs [64]. Whole-body FDG-PET/CT is typically not an initial imaging study but can be used to evaluate for widespread metastatic disease and can distinguish benign versus malignant compression fractures [65,66]. In a patient with suspected spinal infection, MRI without and with IV contrast is preferred because of its high sensitivity and specificity. MRI can localize the site of infection and assess the extent of extradural/epidural and paravertebral involvement. The addition of IV contrast with fat suppression is invaluable in identifying epidural and paraspinal abscess [65] and helps distinguish abscess from phlegmon [67]. Again, MRI allows the diagnosis of infection before bone destruction is evident on either CT or radiography. Noncontrast and contrast-enhanced MRI has the ability to demonstrate inflammatory, neoplastic, and most traumatic lesions, as well as to show anatomic detail not available on isotope studies [68]. Although less sensitive and specific than MRI for evaluation for infection or neoplasm, CT lumbar spine without IV contrast can be obtained to evaluate for associated osseous abnormalities (eg, pathologic fracture, bony destructive change). In some cases, addition of IV contrast may be useful to assess for epidural abscess in such patients [45-47]. CT myelography of the lumbar spine assesses the patency of the spinal canal/thecal sac and of the subarticular recesses and neural foramen [22]. It can be useful in patients with suspected neoplasm and neurologic deficit. This modality has the disadvantage of lumbar puncture and injection of intrathecal contrast [22]. Bone Scan Whole Body with SPECT or SPECT/CT Complete Spine SPECT or SPECT/CT is not the initial imaging study but can be used to evaluate for widespread osseous metastatic disease.


Low Back Pain PCAs

Low Back Pain PCAs. CT Lumbar Spine With IV Contrast CT lumbar spine with IV contrast can be performed to evaluate osseous integrity (eg, pathologic fracture) when involved with tumor. However, intradural and spinal cord pathologies are poorly depicted on CT, so MRI without and with IV contrast is preferred. Addition of IV contrast may be useful to assess for epidural abscess in patients for this clinical scenario and for patients with suspected infection [45-47]. CT Lumbar Spine Without and With IV Contrast CT without and with IV contrast of the lumbar spine is not typically performed as there is no diagnostic advantage to performing a single study with or without IV contrast. Low Back Pain CT Lumbar Spine Without IV Contrast CT lumbar spine without IV contrast can be performed to evaluate osseous integrity (eg, pathologic fracture) when involved with tumor. However, intradural and spinal cord pathologies are poorly depicted on CT, so MRI without and with IV contrast is preferred. Addition of IV contrast may be useful to assess for epidural abscess in patients for this clinical scenario and for patients with suspected infection. [45-47]. CT Myelography Lumbar Spine CT myelography of the lumbar spine assesses the patency of the spinal canal/thecal sac and of the subarticular recesses and neural foramen [22]. It can be useful in patients with suspected neoplasm and neurologic deficit. This modality has the disadvantage of lumbar puncture and injection of intrathecal contrast [22]. Discography and Post-Discography CT Lumbar Spine There is no relevant literature to support the use of discography and post-discography CT lumbar spine in this clinical scenario. FDG-PET/CT Whole Body Whole-body FDG-PET/CT is typically not an initial imaging study but can be used to evaluate for widespread metastatic disease and can distinguish benign versus malignant compression fractures [65,66].


Myelopathy PCAs

Myelopathy PCAs.  Introduction/Background Myelopathy refers to any pathologic process affecting the spinal cord. It is a clinical diagnosis based on signs and symptoms of spinal cord dysfunction [1]. Myelopathy can be due to primary intrinsic disorders of the spinal cord and include neoplastic, infectious, inflammatory, neurodegenerative, vascular, nutritional, and idiopathic disorders [2]. More commonly, however, myelopathy is due to secondary conditions, which result in extrinsic compression of the spinal cord. The most frequently encountered cause of extrinsic compression of the spinal cord in adults is degenerative disease of the cervical and thoracic spine [3]. Other causes of myelopathy from external spinal cord compression include bone metastases and blunt or penetrating trauma. A variety of cysts and benign neoplasms can also compress the cord; they tend to arise within the intradural compartment. The most common of these are nerve sheath tumors, meningiomas, and arachnoid adhesions/cysts [4-10]. Clinically, the diagnosis of myelopathy depends on the localization of the neurological finding to the spinal cord, rather than the brain or peripheral nervous system, and then to a particular segment of the spinal cord [11]. Although the causes of myelopathy may be many, the acuity of presentation and symptom onset provides the clinical team with a practical approach to the differential diagnosis [1,12]. Myelopathy is considered acute if symptoms begin abruptly or have an onset of days to weeks. Myelopathy with a time course of months to years is considered chronic or progressive. Imaging plays a crucial role in refining the differential diagnosis. Historically, radiological evaluation of myelopathic patients consisted of positive contrast myelography. Later, this evaluation was supplemented by CT and CT myelography. MRI is now the mainstay in the evaluation of myelopathy because of its superb contrast resolution of the spinal cord [10,13-15].


Myelopathy PCAs

Myelopathy PCAs. Special Imaging Considerations Although history and physical examination can help localize the myelopathic level, it may be beneficial to study the entire spine, even in the setting of a localized myelopathic level. In certain cases, brain MRI may be a useful adjunct diagnostic test [17]. Newer imaging techniques, such as spinal cord diffusion tensor imaging, appear promising to further interrogate spinal cord injury at a microstructural level [18-21]. aUniversity of Pittsburgh Medical Center, Pittsburgh, Pennsylvania. bPanel Chair, University of Utah, Salt Lake City, Utah. cPanel Vice-Chair, Mallinckrodt Institute of Radiology, Saint Louis, Missouri. dThe Ohio State University Wexner Medical Center, Columbus, Ohio. eUK Healthcare Spine and Total Joint Service, Lexington, Kentucky; American Academy of Orthopaedic Surgeons. fUniversity of Utah Health, Salt Lake City, Utah. gEmory University, Atlanta, Georgia. hMayo Clinic, Rochester, Minnesota. iJohns Hopkins Hospital, Baltimore, Maryland. jUniversity of California Los Angeles, Los Angeles, California; American Academy of Neurology. kUniversity of Michigan, Ann Arbor, Michigan. lJacobi Medical Center, Bronx, New York. mMedical University of South Carolina, Charleston, South Carolina; North American Spine Society. nUniversity of California San Francisco, San Francisco, California. oBarrow Neurological Institute, Phoenix, Arizona; Neurosurgery expert. pUniversity of Colorado School of Medicine, Anschutz Medical Campus, Aurora, Colorado. qSpecialty Chair, Atlanta VA Health Care System and Emory University, Atlanta, Georgia. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through representation of such organizations on expert panels. Participation on the expert panel does not necessarily imply endorsement of the final document by individual contributors or their respective organization. Reprint requests to: publications@acr.org


Myelopathy PCAs

Myelopathy PCAs. OR Discussion of Procedures by Variant Variant 1: Acute onset myelopathy. Initial imaging. The body regions covered in this clinical scenario are cervical, thoracic, and lumbar spine. These body regions might be evaluated separately or in combination as guided by physical examination findings, patient history, and other available information, including prior imaging. Acute myelopathy can be subdivided into noninflammatory and inflammatory causes. Noninflammatory conditions include extrinsic compression of the spinal cord, vascular pathologies, and trauma. Inflammatory conditions include demyelinating diseases (ie, multiple sclerosis), systemic inflammatory diseases, and infection. Although infrequent, spinal cord ischemia can result in acute onset myelopathy and in adults is most commonly the result of atheromatous disease or as a complication of aortic surgery [3]. Other pathologies that may predispose patients to developing spinal cord ischemia include systemic hypotension, thoracoabdominal aneurysms or dissection, sickle cell disease, and spinal arteriovenous malformations (AVMs) [27,28]. Very rarely, patients may develop hematomyelia and subsequently acute myelopathy because of an intrameduallary AVM or spinal artery aneurysm rupture [29,30]. Acute ischemic myelopathy can also develop in the setting of fibrocartilaginous embolic disease [31]. Depending on the level(s) of the spinal cord involved, patients will typically develop acute paraparesis or quadriparesis. Inflammatory conditions that can result in acute myelopathy include demyelinating diseases such as multiple sclerosis (MS), neuromyelitis optica (NMO), and acute disseminated encephalomyelitis (ADEM); systemic inflammatory conditions such as systemic lupus erythematous, Sjogren syndrome, mixed connective tissue disorder, Behcet disease, and sarcoidosis; and infectious diseases [8]. MRI Spine MRI is useful for evaluation of the spinal cord when investigating the etiology of acute myelopathy [32].


Myelopathy PCAs

Myelopathy PCAs. MRI has superior soft-tissue resolution and multiplanar capability, making it ideal for evaluation of the spinal canal and its contents as well as the surrounding osseous and soft-tissue structures [13-15,33-36]. Myelopathy Intramedullary cord signal changes on MRI in patients with spondylotic myelopathy represent prognostic factors for neurosurgical outcome [21,37-41]. Intravenous (IV) contrast is typically not required for the diagnosis of spondylotic myelopathy, but characteristic patterns of enhancement can be seen immediately at and below a level of stenosis [42,43]. In patients who have undergone spinal surgery, complications in the early postoperative setting (eg, hematoma) can result in extrinsic compression of the spinal cord and are best evaluated using MRI without and with IV contrast [44]. In cases in which spinal cord ischemia is suspected as the cause for acute myelopathy, MRI without and with IV contrast is useful in cases where spinal cord ischemic is suspected as the cause for acute myelopathy [27,28,45-47]. Contrast enhancement is typically not seen in the early phase of acute ischemia and, if present, may suggest an alternative inflammatory or infectious etiology [48]. Diffusion-weighted imaging can show signal alteration in the spinal cord earlier after patient symptom onset compared with T2-weighted images [49,50]. As such, diffusion- weighted imaging should be included anytime there is concern for spinal cord ischemia [51]. When considering inflammatory or infections etiologies of myelopathy, visualization of the osseous spinal column as well as the spinal cord is useful and best accomplished noninvasively by MRI [4,7,45,52-60]. Demyelinating diseases such as MS and NMO can present as acute myelopathy. MS is the classic demyelinating disease and is characterized by lesions affecting the spinal cord (and brain) and clinical defects disseminated in space and time [61].


Myelopathy PCAs

Myelopathy PCAs. Spinal cord involvement is seen in 80% to 90% of patients with MS, most commonly affecting the cervical cord [62]. Patients with primary progressive MS tend to have more spinal cord involvement than patients with relapsing-remitting MS [12]. When myelopathy due to MS is suspected, MRI detection of spinal cord lesion(s) fulfills part of the 2016 Magnetic Resonance Imaging in MS (MAGNIMS) criteria [63]. NMO is a demyelinating condition characterized by optic neuritis and spinal cord lesions. Brain lesions are not as commonly encountered in NMO as in MS, so, when present, tend to predominate in regions around the third and fourth ventricles [64-66]. ADEM is a demyelinating condition that typically manifests as encephalopathy. Spinal cord involvement is present in approximately 25% of cases of ADEM. MRI of the spine is generally considered the reference standard for imaging of the spinal cord in cases of suspected demyelinating disease [63,67,68] in addition to excluding alternative etiologies. Contrast-enhanced imaging is recommended for initial diagnostic evaluation [69,70]. MRA Spine There is no relevant literature regarding the use of MR angiography (MRA) in the initial imaging evaluation of acute onset myelopathy. In cases of spinal cord ischemia, MRA can be used to identify the artery of Adamkiewicz or vertebral artery dissection/occlusion and should be considered as a follow-up to MRI [12]. Although MRA can be performed for suspected spinal vascular malformations in patients with hematomyelia, conventional angiography remains necessary for complete lesion characterization [71]. CT Myelography Spine CT myelography may be useful in this clinical setting to answer specific questions before surgical intervention [72,73]. In spondylotic myelopathy, conventional myelography can be used to diagnose severe canal stenosis [74]. MRI, however, is best for evaluation of the marrow and the spinal canal/spinal cord [13-15].


Myelopathy PCAs

Myelopathy PCAs. CT Spine CT can depict bony encroachment on the spinal canal in cases of disc-osteophyte complexes as well as subluxation and compression of neural structures by herniated disc material with better resolution than with radiographs. For inflammatory or infectious processes, CT can be beneficial to evaluate the osseous structures and adjacent soft- tissue involvement [75]. Although CT demonstrates osseous integrity with excellent assessment of bone destruction, MRI provides better visualization of the marrow and the spinal cord [13-15]. CT of the spine is not useful in the initial evaluation of spinal cord ischemia [76]. CTA Spine There is no relevant literature regarding the use of CT angiography (CTA) in the initial imaging evaluation of acute onset myelopathy. In cases of spinal cord ischemia, CTA can be used to identify the artery of Adamkiewicz or vertebral artery dissection/occlusion and should be considered as a follow-up to MRI [12]. Myelopathy Radiography Spine There is no relevant literature supporting the use of radiographs as the initial imaging evaluation of acute onset myelopathy. Although radiographs may demonstrate bone destruction, CT provides better visualization of the osseous spine [13-15]. In spondylotic myelopathy, radiographs may depict osteophytic narrowing of the spinal canal, whereas conventional myelography can be used to diagnose severe canal stenosis [74]. MRI, however, is best for evaluation of the marrow and the spinal canal/spinal cord [13-15]. Lateral radiographs can be obtained as an adjunct to cross-sectional imaging to help assess alignment parameters and dynamic instability [77]. Arteriography There is no relevant literature regarding the use of conventional arteriography in the initial imaging evaluation of acute onset myelopathy. Even in cases of spinal cord ischemia and suspected spinal vascular malformations, conventional arteriography of the spine is not useful for initial evaluation [71,76]. Variant 2: Chronic or progressive myelopathy. Initial imaging.


Myelopathy PCAs

Myelopathy PCAs. The body regions covered in this clinical scenario are cervical, thoracic, and lumbar spine. These body regions might be evaluated separately or in combination as guided by physical examination findings, patient history, and other available information, including prior imaging. Once extrinsic compression of the spinal cord has been excluded, chronic or progressive myelopathy can be subdivided into non-neoplastic and neoplastic causes. Non-neoplastic causes include demyelinating diseases such as MS, NMO, and ADEM; metabolic derangements such as Vitamin B12 (cobalamin) deficiency, copper deficiency, and nitrous oxide inhalation; chronic infections including human T cell lymphotropic virus myelitis, tuberculosis, schistosomiasis, human immunodeficiency virus vacuolar myelopathy, and tertiary syphilis; prior radiation treatment; autoimmune causes including paraneoplastic myelopathy; and vascular abnormalities such as spinal dural AVM/fistulas. Neoplastic causes include primary and metastatic tumors of the spinal cord. MRI Spine MRI is useful for evaluation of the spinal cord when investigating the etiology of chronic or progressive myelopathy [32]. MRI has superior soft-tissue resolution and multiplanar capability, making it ideal for evaluation of the spinal canal and its contents as well as the surrounding osseous and soft-tissue structures [13-15,33-36]. The imaging changes in the spinal cord due to myelomalacia and gliosis are best discerned by MRI [81,82]. Intramedullary cord signal changes on MRI in patients with spondylotic myelopathy represent prognostic factors for neurosurgical outcome [21,37-41]. IV contrast is typically not required for the diagnosis of spondylotic myelopathy, but characteristic patterns of enhancement can be seen immediately at and below a level of stenosis [42,43].


Myelopathy PCAs

Myelopathy PCAs. In patients who have undergone spinal surgery, late complications (eg, adjacent level degenerative disease with spinal stenosis, recurrent disc herniation) can result in extrinsic compression of the spinal cord and are best evaluated using MRI without and with IV contrast [44]. Demyelinating diseases such as MS can present as subacute/chronic myelopathy. MS is the classic demyelinating disease and is characterized by lesions affecting the spinal cord (and brain) and clinical defects disseminated in space and time [61]. Spinal cord involvement is seen in 80% to 90% of patients with MS, most commonly affecting the cervical cord [62]. Patients with primary progressive MS tend to have more spinal cord involvement than Myelopathy patients with relapsing-remitting MS [12]. When myelopathy due to MS is suspected, MRI detection of spinal cord lesion(s) fulfills part of the 2016 MAGNIMS criteria [63]. Other demyelinating processes such as NMO and ADEM can present as chronic myelopathy less commonly. In patients with chronic or progressive myelopathy, MRI of the spinal cord can identify spinal cord lesions suggestive of demyelinating disease in addition to excluding alternative etiologies. Contrast-enhanced imaging is recommended for initial diagnostic evaluation [69,70]. Metabolic causes of chronic or progressive myelopathy result in changes in the spinal cord known as subacute combined degeneration and are best evaluated with MRI [11,83,84]. Chronic infections can have a similar appearance [12]. Radiation-induced myelopathy is a rare dose-dependent complication that anatomically localizes to a prior radiation port [85]. Autoimmune myelitis includes paraneoplastic myelopathy [86,87]. MRI without and with IV contrast is useful to evaluate the spinal cord in these instances. Vascular malformations can likewise present with chronic and slowly progressive myelopathy [88].


Myelopathy PCAs

Myelopathy PCAs. MRI without and with IV contrast is useful to demonstrate spinal cord edema caused by venous hypertension and enlarged veins along the dorsal surface of the spinal cord. There may be patchy intramedullary enhancement due to breakdown of the blood-cord barrier. In some cases, abnormal vasculature may be identified that may be useful to guide spinal arteriography and intervention [5,89-91]. Primary and metastatic tumors of the spinal cord very rarely cause myelopathy and are best evaluated on contrast- enhanced MRI of the spine [92-96]. The distinction of syrinx from tumor, location of small tumor nodules, extent of cyst, and distinction of nodule and cyst from edema are crucial in treatment planning for intramedullary disease and best delineated with MRI [9,97]. In cases in which MRI shows findings suspicious for arachnoid cyst/arachnoid web or ventral cord herniation, CT myelography can be performed for further evaluation [79,80]. Likewise, in cases in which there is clinical concern for positional myelopathy, MRI with flexion/extension can be performed as a follow-up [78]. MRA Spine There is no relevant literature regarding the use of MRA in the initial imaging evaluation of chronic or progressive myelopathy. If MRI demonstrates findings concerning for an underlying vascular malformations, MRA can be performed as a follow-up to demonstrate abnormal vasculature that may be useful to guide spinal arteriography and intervention [5,89-91]. CT Myelography Spine CT myelography may be useful in this setting to answer specific questions before surgical intervention [72,73]. In cases in which MRI shows findings suspicious for arachnoid cyst/arachnoid web or ventral cord herniation, CT myelography can be performed for further evaluation [79,80]. Likewise, in cases in which there is clinical concern for positional myelopathy, extension/flexion positional CT myelography can be performed as a follow-up [98].


Myelopathy PCAs

Myelopathy PCAs. In spondylotic myelopathy, conventional myelography can be used to diagnose severe canal stenosis [74]. MRI, however, is best for evaluation of the marrow and the spinal canal/spinal cord [13-15]. CT Spine CT can depict bony encroachment on the spinal canal in cases of disc-osteophyte complexes as well as subluxation and compression of neural structures by herniated disc material with better resolution than with radiographs. Although CT demonstrates osseous integrity with excellent assessment of bone destruction, MRI provides better visualization of the marrow and the spinal cord [13-15]. It is therefore not useful in the initial evaluation of noncompressive etiologies of chronic or progressive myelopathy. CTA Spine There is no relevant literature regarding the use of CTA in the initial imaging evaluation of chronic or progressive myelopathy. CTA continues to make progress as a preangiographic tool for localization of spinal vascular malformations [99-102]. Radiography Spine There is no relevant literature supporting the use of radiographs as the initial imaging evaluation of chronic or progressive myelopathy. Although radiographs may demonstrate bone destruction, CT provides better visualization of the osseous spine [13-15]. In spondylotic myelopathy, radiographs may depict osteophytic narrowing of the spinal canal, whereas conventional myelography can be used to diagnose severe canal stenosis [74]. MRI, however, Myelopathy is best for evaluation of the marrow and the spinal canal/spinal cord [13-15]. Lateral radiographs can be obtained as an adjunct to cross-sectional imaging to help assess alignment parameters and dynamic instability [77]. Arteriography There is no relevant literature regarding the use of conventional arteriography in the initial imaging evaluation of chronic or progressive myelopathy. Supporting Documents The evidence table, literature search, and appendix for this topic are available at https://acsearch. acr.org/list.


Abnormal Uterine Bleeding

Abnormal Uterine Bleeding.  Although pelvic MRI protocols may vary somewhat between institutions, we specifically note that the addition of a diffusion-weighted imaging sequence is important in the MRI examination of the uterus in women with AUB. Diffusion-weighted imaging has been shown to improve the sensitivity and specificity of MRI for the accurate diagnosis of uterine pathology [14-16]. This has been most extensively studied in endometrial cancer; however, there is ongoing research in using diffusion-weighted imaging for differentiating leiomyosarcomas from benign leiomyomas [16-23]. MR angiography may be incorporated into the MRI protocol in the preprocedural workup of Reprint requests to: publications@acr.org Abnormal Uterine Bleeding leiomyomas prior to uterine artery embolization because the vascular anatomy serves as a road map for the interventional radiologist [24,25]. In the initial assessment of leiomyomas and other uterine pathologies, 3-D US may also be considered, because this technique has the potential to help with spatial assessment and treatment planning [26]. Research is ongoing to determine the clinical accuracy of 3-D US compared with 2-D US alone [27-29]. Three-dimensional US may increase the confidence of the diagnosis and be helpful when communicating with the referring physician on the location and size of uterine pathology [30,31]. US elastography measures tissue stiffness. Small studies have shown that, in combination with routine 2-D US, strain, elastography may increase the diagnostic accuracy of US in differentiating endometrial polyps from submucosal leiomyomas [32] and differentiating leiomyomas from adenomyosis [33]. OR Discussion of Procedures by Variant Variant 1: Abnormal uterine bleeding. Initial imaging. CT Pelvis To our knowledge, there is no relevant literature to support the use of CT pelvis in the initial imaging evaluation of AUB. MRI Pelvis To our knowledge, there is no relevant literature to support the use of MRI pelvis in the initial imaging evaluation of AUB.


Abnormal Uterine Bleeding

Abnormal Uterine Bleeding. US Duplex Doppler Pelvis Although it is rated as a separate imaging procedure per ACR methodology, this document considers Doppler imaging to be a standard component of pelvic US. Color and spectral Doppler are routinely used in pelvic US examinations to evaluate internal vascularity of pelvic findings and distinguish fluid from vascular soft-tissue. US duplex Doppler evaluation of the vascularity of the endometrium can help identify vessels within endometrial polyps or cancer, or the lack of vascularity in the normal endometrium [30]. Visualization of a vascular pedicle during transvaginal color Doppler imaging has a specificity of 62% to 98% and a negative predictive value of 50% to 94% for the detection of endometrial polyps [34-36]. Currently, investigations are ongoing to evaluate whether color Doppler patterns can differentiate endometrial polyps from endometrial cancer [4,34,37]. The addition of Doppler may improve the sensitivity, specificity, and positive predictive value of US for the diagnosis of adenomyosis [38]. To our knowledge, there is no relevant literature that has assessed vascularity of leiomyomas and leiomyosarcomas in order to differentiate these two entities. US Pelvis Transabdominal A combined transabdominal and transvaginal approach is typically used for pelvic US imaging. Transabdominal US is most helpful in the case of a significantly enlarged uterus or uterine tumor, in which the limited field-of-view of TVUS cannot image all portions of the uterus or uterine tumor. US Pelvis Transvaginal TVUS should be combined with transabdominal US whenever possible in order to fully assess the pelvic structures. Combining the anatomic overview provided by the transabdominal approach with the greater spatial and contrast resolution of transvaginal imaging will allow for more complete assessment of the pelvis. TVUS is able to detect Abnormal Uterine Bleeding Leiomyomas and adenomyosis are other structural causes of AUB.


Abnormal Uterine Bleeding

Abnormal Uterine Bleeding. In a meta-analysis of 14 studies including 1,898 women who had US for uterine pathology, the pooled sensitivity and specificity for TVUS for the diagnosis of adenomyosis were 82.5% and 84.6%, respectively [41]. However, detection of adenomyosis at TVUS may be limited if there is coexisting uterine pathology, such as leiomyomas. In one study, the sensitivity and specificity of TVUS for diagnosing adenomyosis in patients with and without leiomyomas were 33.3% and 78% and 97.8% and 97.1%, respectively [47]. US Sonohysterography US sonohysterography, also referred to as hysterosonography, can be used in the setting of AUB, particularly if the initial TVUS demonstrates a focal endometrial abnormality [48]. The technique involves transcervical injection of sterile fluid, such as saline, in combination with routine TVUS [10,49]. Although some authors describe transcervical injection of gel [37], sterile saline is currently the accepted standard endometrial contrast agent [49]. The literature supports the use of US sonohysterography as an examination to further characterize endometrial observations on TVUS [48-51]. Variant 2: Abnormal uterine bleeding. Follow-up imaging when original ultrasound is inconclusive or further imaging characterization is needed. CT Pelvis To our knowledge, there is no relevant literature to support the use of CT pelvis for the reassessment or follow up imaging of AUB. MRI Pelvis When MRI is performed, the use of a gadolinium-based intravenous (IV) contrast agent is preferred. Please refer to the ACR Manual on Contrast Media for additional information [52]. The inclusion of diffusion-weighted sequences should also be strongly considered. In the case of assessing leiomyomas prior to treatment, MRI has been shown to have increased sensitivity and specificity for location and size, in addition to helping exclude the coexistence of a leiomyosarcoma [12,16,17,20,21].


Abnormal Uterine Bleeding

Abnormal Uterine Bleeding. MRI has a sensitivity of approximately 78% and specificity of nearly 93% for the diagnosis of adenomyosis, and it can be used in the reassessment of women with AUB to exclude adenomyosis [13,55]. Abnormal Uterine Bleeding US Duplex Doppler Pelvis Although it is rated as a separate imaging procedure per ACR methodology, this document considers Doppler imaging to be a standard component of pelvic US. US duplex Doppler evaluation of the vascularity of the endometrium can help identify vessels within endometrial polyps or cancer [30,56]. Currently, there are no definitive studies demonstrating whether Doppler can differentiate between benign and malignant endometrial lesions; however, research is ongoing [37,56,57]. US duplex Doppler evaluation of leiomyomas and adenomyosis can be performed; however, there are no definitive studies demonstrating Doppler can differentiate between these two entities [58]. US Pelvis Transabdominal A combined transabdominal and transvaginal approach is most appropriate for pelvic US imaging. Transabdominal US is most helpful in the case of an enlarged uterus or uterine tumor, in which the limited field-of-view of TVUS cannot image all portions of the uterus or uterine tumor. US Pelvis Transvaginal If the initial imaging and clinical evaluation (eg, endometrial sampling) of women with AUB are negative, endometrial cancer in these women is extremely unlikely [10]. Nonetheless, repeat TVUS can be performed to reassess the endometrium, because endometrial cancers may be missed on initial imaging or endometrial sampling [59]. If on repeat imaging, the endometrium remains <4 mm in a postmenopausal woman, the negative predictive value for cancer is nearly 100% [10]. US Sonohysterography US sonohysterography, also referred to as hysterosonography, can be used in the setting of AUB, particularly if the initial TVUS demonstrates a focal endometrial abnormality [48].


Abnormal Uterine Bleeding

Abnormal Uterine Bleeding. The technique involves transcervical injection of sterile fluid, such as saline, in combination with routine TVUS [10,49]. Although some authors describe transcervical injection of gel [37], sterile saline is currently the accepted standard endometrial contrast agent [49]. The literature supports the use of US sonohysterography as an examination to further characterize endometrial observations on TVUS [48-51]. US sonohysterography can help distinguish between leiomyomas and endometrial polyps with pooled accuracies of 97% [51]. With the sonohysterographic features of an intact myometrial- endometrial interface, a single vessel, an acute angle with the endometrium, and a homogenous echogenicity, the likelihood ratio of an endometrial polyp is optimized, whereas the combined features of absent endometrial- myometrial interface, arborized vascular pattern, obtuse angle with the endometrium, and a heterogeneous echogenicity maximizes the likelihood ratio of an intracavitary or submucosal leiomyoma [50]. Despite its ability to differentiate polyps and leiomyomata, sonohysterography cannot distinguish between benign endometrial pathology and endometrial cancer with a high degree of certainty, and endometrial sampling or direct visualization with hysteroscopy is recommended in women with suspected endometrial pathology [10,50,51]. In the setting of focal endometrial pathology, an accurate description of the location of the abnormality may direct hysteroscopic resection. US sonohysterography is helpful to distinguish between focal or diffuse pathology in the setting of a postmenopausal woman with AUB and a thickened endometrium on TVUS [58]. However, US sonohysterography cannot distinguish between benign endometrial pathology and endometrial cancer with a high degree of certainty, and endometrial sampling or direct visualization with hysteroscopy is recommended in women with suspected endometrial pathology [10].


Abnormal Uterine Bleeding

Abnormal Uterine Bleeding. Additionally, US sonohysterography can confirm the diagnosis of endometrial atrophy. Although sonohysterography could be considered in the setting of a previously inconclusive US, there is no current evidence confirming this approach is helpful if the endometrium could not be visualized on conventional TVUS [28]. Variant 3: Abnormal uterine bleeding. Follow-up imaging when surveillance is appropriate given findings from the initial ultrasound. CT Pelvis To our knowledge, there is no relevant literature to support the use of CT pelvis for the reassessment or follow up imaging of AUB. Abnormal Uterine Bleeding MRI Pelvis When MRI is performed, the use of a gadolinium-based IV contrast agent is preferred. Please refer to the ACR Manual on Contrast Media for additional information [52]. The inclusion of diffusion-weighted sequences should also be strongly considered. In the case of assessing leiomyomas prior to treatment or for potential growth, MRI has been shown to have increased sensitivity and specificity for location and size, in addition to helping exclude the coexistence of a leiomyosarcoma [12,16,17,20,21]. MRI has a sensitivity of approximately 78% and specificity of nearly 93% for the diagnosis of adenomyosis, and it can be used in the reassessment of women with AUB to exclude adenomyosis [13,55]. US Duplex Doppler Pelvis Although it is rated as a separate imaging procedure per ACR methodology, this document considers Doppler imaging to be a standard component of pelvic US. US duplex Doppler evaluation of the vascularity of the endometrium can help identify vessels within endometrial polyps or cancer [30,56]. Currently, there are no definitive studies demonstrating whether Doppler can differentiate between benign and malignant endometrial lesions; however, research is ongoing [37,56,57]. US duplex Doppler evaluation of leiomyomas and adenomyosis can be performed; however, there are no definitive studies demonstrating Doppler can differentiate between these two entities [58].


Abnormal Uterine Bleeding

Abnormal Uterine Bleeding. US Pelvis Transabdominal A combined transabdominal and transvaginal approach is most appropriate for pelvic US imaging. Transabdominal US is most helpful in the case of an enlarged uterus or uterine tumor, in which the limited field-of-view of TVUS cannot image all portions of the uterus or uterine tumor. US Pelvis Transvaginal If the initial imaging and clinical evaluation (eg, endometrial sampling) of women with AUB are negative, endometrial cancer in these women is extremely unlikely [10]. Nonetheless, repeat TVUS can be performed to reassess the endometrium, because endometrial cancers may be missed on initial imaging or endometrial sampling [59]. If on repeat imaging, the endometrium remains <4 mm in a postmenopausal woman, the negative predictive value for cancer is nearly 100% [10]. US Sonohysterography US sonohysterography, also referred to as hysterosonography, can be used in the setting of AUB, particularly if the initial TVUS demonstrates a focal endometrial abnormality [48]. The technique involves transcervical injection of sterile fluid, such as saline, in combination with routine TVUS [10,49]. Although some authors describe transcervical injection of gel [37], sterile saline is currently the accepted standard endometrial contrast agent [49]. The literature supports the use of US sonohysterography as an examination to further characterize endometrial observations on TVUS [48-51]. US sonohysterography can help distinguish between leiomyomas and endometrial polyps with pooled accuracies of 97% [51]. With the sonohysterographic features of an intact myometrial- endometrial interface, a single vessel, an acute angle with the endometrium, and a homogenous echogenicity, the likelihood ratio of an endometrial polyp is optimized, whereas the combined features of absent endometrial- myometrial interface, arborized vascular pattern, obtuse angle with the endometrium, and a heterogeneous echogenicity maximizes the likelihood ratio of an intracavitary or submucosal leiomyoma [50].


Occupational Lung Diseases PCAs

Occupational Lung Diseases PCAs.  Despite well-known risks and mitigation efforts, occupational lung diseases such as the pneumoconioses continue to arise for a variety of reasons [4-11]. Medical imaging continues to play a critical role in the diagnosis and management of occupational lung disease, with increasing use of chest CT, particularly at reduced dose [12-14]. Various biomarkers in conjunction with medical imaging are proving to further refine assessment [15-20]. As in other areas of diffuse lung disease, multidisciplinary assessment consistently demonstrates improved characterization of occupational lung disease [21-28]. Special Imaging Considerations Imaging of emerging occupational lung diseases deserves special consideration. Imaging and pathologic manifestations may not be known in the setting of a new and unique exposure, potentially requiring a broader diagnostic evaluation than the variants discussed below [6,29-38]. Discussion of Procedures by Variant Variant 1: Occupational exposure, screening, and surveillance of lung disease. Initial imaging. Radiography Chest Driven by the International Labor Organization classification scheme for screening and surveillance of pneumoconioses, chest radiography remains an important imaging modality in the arena of occupational lung disease. Epidemiologic studies using radiographs to screen United States coal miners continue to demonstrate developing coal workers pneumoconiosis [9,11,39,40]. Screening and surveillance of various occupations with chest radiographs reveal ongoing and new lung disease risks [7,8,41,42]. Additionally, chest radiographs have demonstrated correlation with physiologic testing [43]. In 2011, the International Labor Organization criteria for radiograph acquisition have expanded to include digital radiography with flat-panel detector viewing [44]. More recent studies continue to support the equivalence of analog radiography and digital radiography [40,45-47].


Occupational Lung Diseases PCAs

Occupational Lung Diseases PCAs. CT Chest Although no studies have implemented a population-based CT screening and surveillance program specifically for occupational lung disease to examine morbidity or mortality benefit, several recent studies have used reduced-dose CT to demonstrate adequate detection of parenchymal changes in at-risk workers. In a prospective study of 55 patients with a 15-year asbestos exposure history, screening ultra-low-dose chest CT was compared with standard acquisition chest CT, demonstrating 91% sensitivity and 100% specificity for asbestos-associated primary endpoint findings [12]. Retrospective studies utilizing lung cancer screening examinations have also revealed potential aResearch Author, Mayo Clinic, Rochester, Minnesota. bPanel Chair, University of Chicago, Chicago, Illinois. cMassachusetts General Hospital and Harvard Medical School, Boston, Massachusetts. dStanford University Medical Center, Stanford, California; The Society of Thoracic Surgeons. eThe University of Texas MD Anderson Cancer Center, Houston, Texas. fThe University of Texas MD Anderson Cancer Center, Houston, Texas. gUniversity of Kentucky, Lexington, Kentucky. hMayo Clinic, Rochester, Minnesota. iVanderbilt University Medical Center, Nashville, Tennessee; American College of Chest Physicians. jMayo Clinic Florida, Jacksonville, Florida. kDuke University School of Medicine, Durham, North Carolina; The Society of Thoracic Surgeons. lUniversity of Kansas Medical Center, Kansas City, Kansas. mSpecialty Chair, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels. Participation by representatives from collaborating societies on the expert panel does not necessarily imply individual or society endorsement of the final document. Reprint requests to: publications@acr.org Occupational Lung Diseases


Occupational Lung Diseases PCAs

Occupational Lung Diseases PCAs. benefit. For instance, Carrillo et al [48] found 44% of patients with an asbestos exposure history had associated pulmonary parenchymal abnormalities on low-dose CT performed for lung cancer screening. The International Classification of High-Resolution Computed Tomography for Occupational and Environmental Respiratory Diseases aims to standardize high-resolution CT (HRCT) findings for occupational screening [49]. CT with intravenous (IV) contrast serves no purpose in the setting of occupational lung disease screening and surveillance. MRI Chest Though there is evidence that shows that proton MRI may be useful in the setting of interstitial lung disease (ILD) and pulmonary fibrosis [50-53], there is no direct evidence to support the use of MRI as an initial imaging technique in population-based screening and surveillance of occupational lung disease. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG)-PET/CT as an initial imaging technique in population-based screening and surveillance of occupational lung disease. Variant 2: Occupational exposure, suspected interstitial lung disease. Initial imaging. Radiography Chest The chest radiograph and CT are complementary in the initial workup of suspected occupational lung disease [21,24,54,55]. When patients with occupational exposures present with respiratory symptoms, chest radiography serves as the primary function of excluding alternative diagnoses, such as infectious pneumonia or pulmonary edema, with HRCT findings offering the best characterization of lung disease. CT Chest The primary imaging modality for symptomatic occupational lung disease is chest HRCT that often provides a definitive diagnosis, obviating the need for surgical biopsy.


Occupational Lung Diseases PCAs

Occupational Lung Diseases PCAs. Ongoing studies continue to support the increased sensitivity and specificity of HRCT over chest radiography for changes related to occupational lung disease [26,43,56-58], although the level of radiologist expertise can affect interpretation [59]. HRCT proves central in the imaging of classic and emerging pneumoconioses [6,34,60-64], as well as differentiating occupational lung disease from other ILDs [65,66]. New HRCT findings are revealing additional imaging characteristics important to the diagnosis of occupational lung disease [67-70]. A negative chest CT also proves useful in excluding disease [71]. The International Classification of High-Resolution Computed Tomography for Occupational and Environmental Respiratory Diseases recently demonstrated correlation with physiologic testing [72]. Finally, CT imaging findings can provide prognostic value [73]. CT with IV contrast serves no purpose in the setting of suspected ILD. MRI Chest There is limited research supporting the use of MRI in occupational lung disease, none of which supports the use of MRI as the initial imaging. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of FDG-PET/CT in the initial imaging evaluation of suspected occupation-associated ILD. Variant 3: Occupational exposure, suspected interstitial lung disease based on radiography. Next imaging study. CT Chest Chest radiography performed for screening, surveillance, or diagnostic reasons may reveal findings characteristic of occupational lung disease or nonspecific findings in the setting of reported occupational exposure [43,56]. When ILD is suspected on radiographs, chest HRCT again plays the central role in imaging diagnosis, not only further characterizing true lung disease but also increasing specificity by identifying false-positives [57,74].


Occupational Lung Diseases PCAs

Occupational Lung Diseases PCAs. As noted above, the use of chest CT to diagnose occupation-related ILD may avoid the need for lung biopsy, differentiate occupational lung disease from other diffuse lung diseases [66,73], and identify emerging occupational lung diseases [34,60-63]. CT findings in occupational lung disease may correlate with physiologic testing [72] and assist in determining prognosis [73]. CT with IV contrast serves no purpose in the setting of suspected ILD. However, IV contrast can be helpful in identifying nonpulmonary manifestations of occupational exposure. MRI Chest Select fast MRI sequences have approached the image quality of CT in characterizing progressive massive fibrosis in the setting of pneumoconiosis [75]. A few recent studies have evaluated MRI for identifying ILD to include the use of 3T MRI with and without IV contrast in the setting of pulmonary fibrosis [51,53] and 1.5T MRI in systemic Occupational Lung Diseases sclerosis [52], suggesting feasibility for differentiating normal lung from ILD. However, MRI has not been specifically studied for imaging of suspected occupation-associated ILD based on radiography. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of FDG-PET/CT in the evaluation of population-based screening and surveillance of occupational lung disease. Image-Guided Transthoracic Needle Biopsy There is no relevant literature to support the use of image-guided transthoracic needle biopsy for the evaluation of the diagnosis of ILD based on radiography. Variant 4: Occupational exposure, suspected airway disease. Initial imaging. Radiography Chest Similar to suspected ILD, chest radiography serves a complementary role to chest HRCT in the evaluation of suspected airway disease, although airway findings, if present, are nonspecific on chest radiography [21,24,54,55].


Occupational Lung Diseases PCAs

Occupational Lung Diseases PCAs. Chest radiography primarily excludes alternative or complicating diagnoses, such as infectious pneumonia or pulmonary edema, with HRCT providing the best imaging characterization of airway disease. CT Chest Hypersensitivity pneumonitis typically presents with a combination of pneumonitis and small airway obstruction, producing characteristic findings on chest HRCT with expiratory imaging [76,77]. New and changing occupational exposures causing hypersensitivity pneumonitis are continually described, highlighting the importance of high clinical suspicion and evaluation with HRCT [33,78,79]. Imaging features of hypersensitivity pneumonitis on HRCT also provide predictive information regarding disease behavior [68,80-90] and drive treatment decisions [91]. Certain occupational inhalational exposures, such as diacetyl acetate and carbon dust, may lead to more isolated airway disease, such as constrictive bronchiolitis, bronchial anthracofibrosis, and occupational asthma. Various occupations, such as flavoring microwave popcorn, processing coffee, and serving on military deployment to Iraq/Afghanistan, can result in constrictive bronchiolitis [29-31] evident on HRCT with expiratory imaging [92]. Of note, a few studies over time have demonstrated the importance of tissue biopsy in the setting of negative HRCT but clinically suspected occupational small airway disease [30,93]. In large airway disease, CT may assist in certain diagnoses, such as isolated bronchial anthracofibrosis [35,93,94], although medical imaging has limited value in occupational asthma outside of diagnosing alternative disease. CT with IV contrast serves no purpose in the setting of suspected occupational airway disease. MRI Chest No specific studies have examined the use of MRI in the setting of occupation-associated airway disease.


Occupational Lung Diseases PCAs

Occupational Lung Diseases PCAs. Although substantial literature supports research and clinical use of MRI for the study of other large and small airway diseases, such as chronic obstructive airway disease, asthma, lung transplant, and cystic fibrosis. [95-100]. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of FDG-PET/CT in the initial imaging evaluation of suspected occupation-associated airway lung disease. Occupational Lung Diseases neoplasm but generally in the context of additional complementary imaging [112]. Chest CT has known limitations for diagnosis of malignancy, often requiring alternative imaging assessment or diagnostic testing [109,111]. MRI Chest MRI has been shown in some small studies to be useful in the setting of occupational lung disease and suspected malignancy. For instance, it can be helpful in differentiating progressive massive fibrosis from malignancy [113], characterizing known pleural mesothelioma [114,115], and distinguishing benign from malignant lymphadenopathy [116]. MRI chest with and without contrast is recommended over MRI chest without contrast for increased detection and characterization of pleural malignancy, particularly for mesothelioma diagnosis [117]. FDG-PET/CT Skull Base to Mid-Thigh Recent studies reveal mixed potential benefit of PET/CT for the evaluation of potential malignancy complicating occupational lung disease. PET/CT poorly differentiates benign from malignant changes in progressive massive fibrosis [118,119] but can provide benefit in the diagnosis of pleural and lung malignancies in asbestos exposure [120-122]. The decision between CT surveillance, PET/CT, and lesion biopsy is generally situational and should be determined in the setting of multidisciplinary discussions. Image-Guided Transthoracic Needle Biopsy Transthoracic needle biopsy is a well-established diagnostic test in the workup of suspected thoracic neoplasm, with diagnostic accuracy ranging from 77% to 93% [123-125].


Developmental Dysplasia of the Hip Child.  Introduction/Background Developmental dysplasia of the hip (DDH) comprises a spectrum of abnormalities from hip instability to frank dislocation [1,2]. The mildest end of the spectrum overlaps with physiologic immaturity, therefore making it difficult to determine its true incidence, which is estimated to be 1.5 to 20 per 1,000 births, depending on the demographics of the study population and the inclusion criteria [3-5]. The diagnosis and monitoring of teratologic hips from neuromuscular or syndromic causes will not be covered. The pathophysiology of DDH is multifactorial and not completely understood. The 2 leading causes are laxity induced by maternal hormones and limited in utero hip mobility. In infants with DDH, abnormally increased laxity of the hip capsule and surrounding ligaments have been attributed to the effects of maternal hormone relaxin [1] and a higher concentration of estrogen receptors [6]. In utero restriction to hip mobility can be encountered with oligohydramnios, first-born infants, and prolonged breech positioning. Breech fetal positioning produces extreme hip flexion with knee extension. This leads to shortening and contracture of the iliopsoas muscle, which promotes femoral head dislocation. Studies demonstrating increased prevalence of DDH among monozygotic twins as compared to dizygotic twins [7] and chromosomal analysis in familial DDH and population-based DDH suggest genetic predisposition to DDH [8-10]. Reprint requests to: publications@acr.org In the past 2 decades, imaging has become an integral part of screening, diagnosis, and monitoring of children with DDH [20]. A prospective 33-center United Kingdom Hip Trial [37] found that US of children with clinically detected hip instability allowed for a reduction in abduction splinting and was not associated with an increase in abnormal hip development or higher rates of surgical intervention [37].


Developmental Dysplasia of the Hip Child. Special Imaging Considerations US US is performed using a high-frequency linear array transducer [38]. Two techniques have emerged: a static acetabular morphology method proposed by Graf and a dynamic stress technique proposed by Harcke [39-42]. Radiography An anteroposterior radiograph of the pelvis with the hips in neutral position allows visualization of the femoral head ossific nucleus and acetabular morphology. Proper positioning is critical as both pelvic rotation and inclination can hinder diagnostic accuracy, producing false-positive and false-negative results. Discussion of Procedures by Variant Variant 1: Child, younger than 4 weeks of age. Equivocal physical examination or risk factors for DDH. Initial imaging. For infants with equivocal physical examination or risk factors for DDH, there is evidence that the vast majority spontaneously normalize [21,55,56], and a short delay in intervention has no negative impact on outcome [22,57,58]. Therefore, the potential benefits of early diagnosis and treatment must be weighed against the risk of overtreatment and potential for iatrogenic complications [31]. Thus, the AAP recommends screening with US at the age of 4 to 6 weeks [1], and the American Academy of Orthopaedic Surgeons (AAOS) recommends pediatric orthopedic referral before 4 weeks of age [20]. US Hips Although US can be performed shortly after birth, its high sensitivity for the detection of mild acetabular immaturity and minor degrees of hip laxity can suggest pathology, potentially leading to overdiagnosis (false- positives) and overtreatment [3,5,18]. Therefore, US is not recommended during the newborn period [59]. Radiography Pelvis There is no relevant literature regarding the use of radiographs for screening of DDH in children <4 weeks of age. Variant 2: Child, between 4 weeks to 4 months of age. Equivocal physical examination or risk factors for DDH. Initial imaging.


Developmental Dysplasia of the Hip Child. Although most physicians recommend the first imaging screening for nondislocated hips to be performed at 4 to 6 weeks of age, thus allowing time for normalization of neonatal physiologic immaturity and laxity, this remains an arbitrary time-point, balancing the risk of increased false-positive studies in early age with the potential benefits of early treatment. In a study of 5,170 infants screened at 1 month of age, 99.6% remained normal and 84% to 95% of Graf type II hips normalized at 3 months, indicating that the vast majority continue to normalize after the first month of life [60]. Because of the high false-positive rate of diagnosis with US, the AAP recommends selective US only in the highest risk group, girls with breech presentation at birth [1]. AAP also suggests US as an option in girls with a positive family history, boys with breech presentation, and when the physical examination is inconclusive [1]. US Hips A prospective study using US screening was performed on 2,578 children with an unstable hip on physical examination or risk factors for developmental dysplasia. Screening US was shown to reduce the number of delayed diagnoses and decrease the rate of surgical intervention when compared to clinical screening alone [61]. Other studies have shown that US can help confirm the diagnosis of DDH, leading to a change in the clinical management [62,63]. Variant 3: Child, younger than 4 months of age. Physical findings of DDH. Initial imaging. For the purpose of this variant, positive physical examination is defined as a positive Barlow or Ortolani test, which implies an unstable femoral head that can be dislocated or relocated, respectively [66]. US Hips The AAP guideline published in 2000 [1] did not recommend US screening after a positive physical examination. However, recent studies have shown that 41% to 58% of abnormal findings from a physical examination were Variant 4: Child, between 4 to 6 months of age. Concern for DDH. Initial imaging.


Developmental Dysplasia of the Hip Child. Late-presenting DDH, defined as diagnosis after 3 months of age, is uncommon, occurring at an estimated rate of 0.22 per 1,000 births [55]. At this age, the clinical assessment is less reliable and imaging is often required to confirm the diagnosis. By 8 to 12 weeks of age, the capsule laxity decreases, muscle tightness increases, and the Barlow and Ortolani maneuvers may not be positive regardless of the status of the femoral head. Thus, the finding of limited hip abduction becomes the most important screening method in older children. However, currently there is no consensus on the reliability of this test for diagnosing DDH [5], with one study demonstrating a positive predictive value of 40% for DDH that can increase up to 55% after 8 weeks of age [36], while another study demonstrated no correlation between a positive abduction test and an abnormal acetabular angle [66]. Other screening methods, such as the findings of asymmetric skin folds in the proximal thigh and shortening of the limb on the dislocated side, lack specificity for the diagnosis of DDH [66]. These inconsistencies among various studies may reflect differences in patient selection or inclusion, expertise of the examiners, and the defined gold standard [1,67-69]. US Hips The AAP and AAOS do not advocate the use of US for the screening of DDH after 4 to 5 months [1,20]. There is limited evidence on the use of US for screening of DDH beyond 4 months. A study that obtained anteroposterior radiographs in patients who are 4 to 6 months of age with positive US found that US overdiagnosed DDH in 40% of patients [58]. Radiography Pelvis Shortly after the appearance of the ossific nucleus, pelvic radiography becomes the preferred confirmatory imaging modality, as it allows for the assessment of the femoral head ossific nucleus, the development of the proximal femur, and bony acetabular morphology [1].


Developmental Dysplasia of the Hip Child. Normal pelvic radiograph at 4 months can reliably exclude DDH in children with risk factors [56] and decrease the need for treatment in infants who are 4 to 6 months of age with positive US by 40% [58]. This eliminates unnecessary serial follow-ups and potential for iatrogenic treatment-related complications. Thus, for infants with suspected hip dysplasia, a radiograph is often obtained between 4 to 6 months of age [21,56-58]. However, there are a few limitations to pelvic radiograph. The timing for the appearance of the ossific nucleus varies widely, from 1.5 to 8 months of age [65], and in dysplastic hips, its appearance is often delayed and, when it does appear, is often eccentric [54,70]. US Hips There is insufficient evidence to recommend the use of US as the evaluation may be inadequate because of the suboptimal visualization of the anatomy of the hip joint from decreased acoustic penetration. Radiography Pelvis Shortly after the appearance of the ossific nucleus, pelvic radiography becomes the preferred imaging modality as it facilitates the assessment of the femoral head ossific nucleus and the development of the proximal femur and bony acetabular morphology [1]. There is ongoing debate regarding the necessity of serial radiographic studies for Variant 6: Child, younger than 6 months of age. Known diagnosis of DDH, nonoperative surveillance imaging in harness. The treatment algorithm for DDH varies among practices but typically includes a trial of nonoperative management using abduction splinting, often with a Pavlik harness. The efficacy of the Pavlik harness decreases with age. It is most effective if the harness is applied before 6 weeks of age, and the harness can be used up to 6 months of age. The overall success rate of the harness ranges from 67% to 83% [28]. Surgical intervention is typically reserved for children with severe dysplasia or dislocation, late presentation or diagnosis, or failed nonoperative management [73].


Acute Nonlocalized Abdominal Pain

Acute Nonlocalized Abdominal Pain.  Associated fever with abdominal pain constitutes an even more challenging clinical situation. Fever raises clinical suspicion of an intra-abdominal infection, abscess, or other condition that may need immediate surgical or medical attention. When fever is present, the need for quick, definitive diagnosis is considerably heightened. Imaging is especially helpful in the elderly with acute abdominal pain and fever. In this population, many laboratory tests are nonspecific and may be normal despite serious infection [4-6]. The neutropenic patient is a diagnostic challenge as typical signs of abdominal sepsis may be masked, diagnosis may be delayed [7], and it is associated with a high mortality rate [8]. It is important to note that this overview of imaging focuses on the evaluation of patients with nonspecific abdominal pain, with or without fever, abdominal pain in the setting of recent surgery, and immunocompromised patients with acute abdominal pain. In addition, unless otherwise stated, the ratings and recommendations for this document specifically relate to the adult nonpregnant patient, although the narrative briefly discusses some imaging approaches for younger and pregnant patients in Variant 4. Refer to other Appropriateness Criteria topics aLahey Hospital and Medical Center, Burlington, Massachusetts. bMallinckrodt Institute of Radiology, Saint Louis, Missouri. cResearch Author, Lahey Hospital and Medical Center, Burlington, Massachusetts. dPanel Chair, University of Wisconsin Hospital & Clinics, Madison, Wisconsin. eGeorgetown University Hospital, Washington, District of Columbia; American College of Surgeons. fThe University of South Florida Morsani College of Medicine, Tampa, Florida. gUniversity of Texas McGovern Medical School, Houston, Texas; American Gastroenterological Association. hNewton-Wellesley Hospital, Newton, Massachusetts. iVirginia Tech Carilion School of Medicine, Roanoke, Virginia. jMassachusetts General Hospital, Boston, Massachusetts.


Acute Nonlocalized Abdominal Pain

Acute Nonlocalized Abdominal Pain. kUniversity of Virginia Health System, Charlottesville, Virginia. lMedstar Georgetown University Hospital, Washington, District of Columbia. mDuke University Medical Center, Durham, North Carolina. nEmory University, Atlanta, Georgia. oThe Warren Alpert School of Medicine at Brown University, Providence, Rhode Island. pPenn State Health, Hershey, Pennsylvania. qBeth Israel Deaconess Medical Center, Boston, Massachusetts. rUniversity of California San Francisco, San Francisco, California. sSpecialty Chair, Virginia Commonwealth University Medical Center, Richmond, Virginia. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels. Participation by representatives from collaborating societies on the expert panel does not necessarily imply individual or society endorsement of the final document. Reprint requests to: publications@acr.org Acute Nonlocalized Abdominal Pain Discussion of Procedures by Variant Variant 1: Acute nonlocalized abdominal pain and fever. No recent surgery. Initial imaging. Patients suspected of having abdominal abscesses may present in a number of ways: with fever, with diffuse or localized abdominal pain, or with a history of a condition that may predispose to abdominal abscesses, such as appendicitis, diverticulitis, inflammatory bowel disease, pancreatitis, etc. In addition, some malignant conditions (including lymphoma and necrotizing masses), as well as masses producing secondary infections, such as cholangitis in the setting of a pancreatic malignancy, could all present with abdominal pain and fever. Radiography Abdomen Although the use of radiographs has shown high sensitivity (90%) for detecting intra-abdominal foreign bodies and moderate sensitivity for detecting bowel obstruction (49%), its low sensitivity for sources of abdominal pain and fever or abscess limit its role in this setting [15].


Acute Nonlocalized Abdominal Pain

Acute Nonlocalized Abdominal Pain. Radiography demonstrates low overall sensitivity in the detection of colitidies and enteritidies, and even low-dose CT demonstrates superior diagnostic yield in comparison with abdominal radiography [16]. Many authors suggest that they have a limited role in the evaluation of nontraumatic abdominal pain in adults [17-22]. Fluoroscopy Contrast Enema No current literature supports the use of contrast enema for evaluating patients with nontraumatic abdominal pain and fever in the absence of recent surgery. Fluoroscopy Upper GI with SBFT No current literature supports the use of an upper GI series with small bowel follow-through (SBFT) for evaluating patients with abdominal pain and fever in the absence of recent surgery. CT Abdomen and Pelvis With a generally broad differential and need for fast imaging because of clinical acuity, CT is a preferred imaging option [23]. CT can be performed without and/or with intravenous (IV) contrast and with or without positive oral contrast. Most commonly, in the setting of nonlocalized, nontraumatic abdominal pain, a routine CT of the abdomen and pelvis is performed with IV contrast and a single postcontrast phase. In this setting, precontrast and postcontrast images are not required for diagnosis. Abdominal CT without the use of oral or IV contrast has been advocated as an alternative to abdominal radiographs for evaluating appendicitis [17,24]. However, the use of IV contrast increases the spectrum of detectable pathology in patients with nonlocalized pain [25,26]. Many institutions do not routinely use oral contrast because of the associated delay in scan acquisition and departmental throughput balanced against questionable diagnostic advantage [27-30]. Contraindications are not considered in the appropriateness assessment.


Acute Nonlocalized Abdominal Pain

Acute Nonlocalized Abdominal Pain. Although sensitivity and specificity ranges are not routinely reported because of the wide spectrum of pathology encountered, there are sufficient data to suggest that CT with IV contrast adds diagnostic value and helps direct management. In a prospective study assessing impact of CT on management decisions in the ED, a total of 584 patients presented with nontraumatic abdominal complaints and CT changed leading diagnosis in 49%, changed admission status in 24%, and altered surgical plans in 25% [31]. In the same study, with concerns to etiologies associated with fever, the diagnosis of abscess decreased by 19% following CT, colitis and inflammatory bowel disease decreased by 12%, diagnosis of cholecystitis and cholangitis increased by 100%, and diagnosis of pelvic inflammatory disease increased by 280% following CT. Among intensive care unit patients with sepsis of unknown origin, CT of the abdomen and pelvis revealed the source of sepsis in 7 of 45 patients [32]. Pseudomembranous (ie, clostridium difficile) colitis is frequently encountered in the inpatient setting and is a common diagnostic consideration in a patient with fever; CT findings are present in the colon in 88% of cases [33]. Rarely, diffuse tumors such as lymphomas or metastases may present with abdominal pain and fever; CT with contrast will depict all abdominal organs and lymph node chains in the evaluation of potential malignancy. Acute Nonlocalized Abdominal Pain In addition to detection of an abscess, CT can also be used as guidance for percutaneous drainage. Percutaneous drainage is feasible and effective for the treatment of abdominopelvic abscess [34]. MRI Abdomen and Pelvis MRI is often performed with specific indications in mind, using tailored protocols. However, when optimized for the acute setting, MRI can be an accurate examination for detecting abdominal and pelvic abscesses [35].


Acute Nonlocalized Abdominal Pain

Acute Nonlocalized Abdominal Pain. A prospective study of consecutive patients presenting with acute abdominal pain investigated the use of a rapid acquisition noncontrast MRI protocol for determining the source of abdominal pathology [36]. The MRI was positive in 116 of 349 cases and indeterminate in 3 cases. Overall accuracy was 99% and only 3 cases with negative MRIs later required appendectomies. A range of pathologies were detected, including SBO, diverticulitis, pelvic inflammatory disease, pyelonephritis, renal abscess, pseudomembranous colitis, and diverticular abscess. A rapid MRI protocol may be beneficial in this setting. In a separate retrospective study of MRI with IV contrast in patients with pelvic pain, MRI depicted acute appendicitis with 100% sensitivity and 92% positive predictive value and ovarian torsion with a sensitivity of 86% and specificity of 100% [37]. Given its accuracy for a range of intra-abdominal pathologies [36,37], as well as the feasibility of distinguishing infected from noninfected fluid [38], MRI may be used as an alternative to CT. It should be noted that, in practice, the feasibility of MRI for acute abdominal pain will rely on institutional expertise, availability, and adoption of protocols that are aimed at rapid acquisition and multiorgan assessment, such as that used in the study by Byott and Harris [36]. US Abdomen Ultrasound (US) in general is less sensitive and specific than CT for nonlocalized abdominal pain workup. One retrospective review of 92 patients who underwent multiple studies to specifically evaluate for an intra-abdominal abscess demonstrated a sensitivity and specificity for US of 75% and 91%, respectively, compared to 88% and 93%, respectively, for CT [39].