Thoracoabdominal Aneurysm or Dissection Treatment Planning and Follow Up. If venous phase or unenhanced CT has already been performed, additional imaging with CTA may not be required in some patients. CT Chest and Abdomen Without and With IV Contrast There is no relevant literature regarding venous phase CT chest, abdomen, and pelvis with noncontrast phase for the follow-up of open repair of TAAA or dissection. Compared with CT of the chest, abdomen, and pelvis, evaluation of the chest and abdomen only without imaging of the pelvis may fail to detect changing or new pathology in the pelvic vasculature. If venous phase or unenhanced CT has already been performed, additional imaging with CTA may not be required in some patients. CT Chest and Abdomen Without IV Contrast There is no relevant literature for CT chest and abdomen without IV contrast in the evaluation of follow-up of open repair of TAAA or dissection. Compared with CT of the chest, abdomen, and pelvis, exclusion of the pelvis may fail to detect changing or new pathology in the pelvic vasculature. If venous phase or unenhanced CT has already been performed, additional imaging with CTA may not be required in some patients. CTA Chest, Abdomen, and Pelvis With IV Contrast CTA of the chest, abdomen, and pelvis with IV contrast uses fast scan times to allow for rapid evaluation of the aorta. Acquisition of thin axial slices with subsequent reconstruction along with extensive and homogenous luminal opacification allows for precise and reproducible measurements of the aorta, which are valuable for monitoring aortic growth and interval changes [33,34]. In addition to monitoring aortic size and postsurgical complications such as anastomotic pseudoaneurysm, CTA can evaluate for endograft complications, kinking or occlusion/stenosis of branches of the graft, infection, or complications including thoracoabdominal aneurysm rupture or dissection extension [31,35]. Evidence comparing CTA with MRA for follow-up after surgical thoracoabdominal aortic repair is limited.


Thoracoabdominal Aneurysm or Dissection Treatment Planning and Follow Up. A 2015 review of imaging of the thoracic aorta concluded that contrast-enhanced CT was the optimal modality evaluation of the aorta after surgical repair, although MRI is also comparable and with image resolution comparable to CTA [33]. Compared with CTA of the chest and abdomen, imaging of the pelvis carries the benefit of evaluation of the iliofemoral vessels to assess for new or worsening pathology of the pelvic vessels. CTA Chest and Abdomen With IV Contrast Compared with CTA of the chest, abdomen, and pelvis, CTA of the chest and abdomen may fail to identify new or worsening pelvic pathology. MRA Chest, Abdomen, and Pelvis Without and With IV Contrast MRA of the chest, abdomen, and pelvis without and with IV contrast can be used as an alternative to CTA for follow-up after open thoracoabdominal aortic repair. Spatial resolution of MRA is not as high as CTA, although some authors have found MRI to be an alternative option for imaging in younger patients [33]. In addition to monitoring aortic size and postsurgical complication such as anastomotic pseudoaneurysm, CTA can evaluate for graft complications, kinking or occlusion/stenosis of branches of the graft, infection, or complications including thoracoabdominal aneurysm rupture or dissection extension. MRA can also assess flow dynamics including wall stress and turbulent flow patterns, which may be valuable in certain patients [23,24]. Compared with MRA of the chest and abdomen, imaging of the pelvis carries the benefit of evaluation of the iliofemoral vessels to assess for new or worsening pathology of the pelvic vessels. The drawback of inclusion of the pelvis is increased acquisition time. MRA Chest, Abdomen, and Pelvis Without IV Contrast Evidence supporting use of MRA without IV contrast for evaluation after open thoracoabdominal aortic repair is limited compared with evidence of MRA with IV contrast.


Thoracoabdominal Aneurysm or Dissection Treatment Planning and Follow Up. Similar to CTA, MRA of the thoracoabdominal aorta allows for precise and reproducible assessment of aortic sac size in aneurysm or extent of dissection in thoracoabdominal aortic dissection [33,37-39]. Multiple unenhanced Thoracoabdominal Aortic Aneurysm or Dissection MRA techniques such as time-of-flight, phase-contrast imaging, and SSFP have been developed that allow for evaluation of aortic dissection and aneurysm, including after open surgical repair [44,45]. Even without IV contrast, MRA can be used to precisely evaluate the thoracoabdominal aorta [37,39]. A 2017 observational study comparing AAA measurements in contrast-enhanced CTA and noncontrast-enhanced MRA showed strong agreement, with intraclass coefficient >0.99 and interobserver reproducibility >0.99 for both CTA and MRA [45]. Although some studies have shown more accurate measurements with contrast-enhanced MRA compared with noncontrast-enhanced MRA, other studies have shown equal ability to detect aortic pathology and to measure aortic size [44,50,51]. A 2014 study comparing thoracic aortic measurements and pathology in 76 patients undergoing both contrast- and noncontrast-enhanced MRA showed high agreement between study types, with low intra- and interobserver dependency (intraclass correlation coefficient 0.99) [51]. A similar 2017 study comparing thoracic aorta measurements/findings on contrast- and noncontrast-enhanced MRA performed on a group of 50 patients favored noncontrast-enhanced MRA over contrast-enhanced MRA as the technique of choice because of superior image quality and better vessel sharpness in the ascending aorta [44]. Although these studies do not focus on postsurgical patients, the findings are likely applicable to this patient population.


Thoracoabdominal Aneurysm or Dissection Treatment Planning and Follow Up. MRA Chest and Abdomen Without and With IV Contrast Compared with MRA of the chest, abdomen, and pelvis, imaging of the chest and abdomen reduces acquisition time, although is unable to assess for new or worsening pathology within the pelvis. MRA Chest and Abdomen Without IV Contrast Compared with MRA of the chest, abdomen, and pelvis, imaging of the chest and abdomen reduces acquisition time, although is unable to assess for new or worsening pathology within the pelvis. Radiography Chest There is no relevant literature for radiography in the evaluation of follow-up of open repair of TAAA or dissection. After surgical repair of the thoracoabdominal aorta, radiography is unlikely to carry a sufficient sensitivity or specificity to be used routinely. Radiography Chest Abdomen Pelvis There is no relevant literature for radiography in the evaluation of follow-up of open repair of TAAA or dissection. After surgical repair of the thoracoabdominal aorta, radiography is unlikely to carry a sufficient sensitivity or specificity to be used routinely. US Duplex Doppler Aorta Abdomen Duplex US of the abdominal aorta is an option for evaluation of the thoracoabdominal aorta, although the ability to evaluate the aorta above the diaphragm may be markedly limited by acoustic windows. Prior studies comparing US, CT, and MRI of the abdominal aorta found that US is a reliable method to diagnose and follow AAAs [56]. In the evaluation of thoracoabdominal aortic dissection, US can also be used to evaluate blood flow in the true and false lumens and to directly and dynamically monitor the motion of dissection flaps [43]. As such, abdomen US can be performed serially to evaluate for aortic size changes or dissection hemodynamic changes. However, a limited ability to evaluate the thoracic aorta with dependence on patient acoustic windows could result in poor image quality or the inability to view changes to the aorta. Thoracoabdominal Aortic Aneurysm or Dissection


Suspected Spine Infection PCAs

Suspected Spine Infection PCAs.  Introduction/Background Spine infection is a disease that occurs when either microorganisms or viruses invade and involve one or more structures within or surrounding the spine [1-7]. Although uncommon, the incidence of spine infection appears to be increasing because of a combination of predisposing factors, such as an increasing number of susceptible hosts, an increase in the number of interventional and surgical spine procedures, and an increase in diagnostic testing [5,8- 11]. Potential host factors include preexisting extraspinal infection (endocarditis, HIV, pulmonary infection), intravenous (IV) drug use, diabetes mellitus, hepatic or renal failure, rheumatologic disease, or immunosuppression [12,13]. Spine infection presents a diagnostic and management challenge [14]. Diagnostic delay is not uncommon because of an often indolent clinical presentation with nonspecific presenting signs and symptoms such as back pain, fever, and, less commonly, neurologic compromise [3,8,10]. The location of the spine infection is also important because it may influence the clinical presentation and the subsequent imaging evaluation. One or more spine structures and/or compartments may be infected, and this also influences the imaging findings [1,14]. Spine infection is often extradural, initially invading the vertebral endplate in adults via a hematogenous route and centering about the vertebral endplate (osteomyelitis) and intervertebral disc (discitis). Spine infection may also arise initially within a facet joint. Spine infection occurs less frequently in children and initially affects the intervertebral disc [15]. Epidural and paraspinal soft tissue involvement are not uncommon [16,17]. Other important clinical manifestations of spine infection with imaging and management implications include epidural (abscess), subarachnoid (meningitis) space involvement, or spinal cord involvement (myelitis) [18,19].


Suspected Spine Infection PCAs

Suspected Spine Infection PCAs. Multilevel or multifocal spine infection may be observed in specific patient groups, such as IV drug users, postoperative spine patients, or in geographic regions with endemic infections such as tuberculosis, coccidioidomycosis, or neurocysticercosis [5,20-22]. The type of infection, whether pyogenic, granulomatous, parasitic, or viral, will likewise influence the clinical and imaging presentation [2,4,5,7,23-26]. Imaging is important for suggesting the diagnosis of spine infection, guiding percutaneous spine biopsy procedures, defining the full extent of infection for the purposes of determining medical and/or surgical management, and for possible clinical follow-up [27-31]. Diagnostic imaging can be used to assess suspected spinal cord compression as well as to evaluate for potential spinal instability, either of which, if present will influence surgical intervention [8,32]. Several diagnostic imaging examinations have been previously utilized in the evaluation and management of spine infection and include radiography, CT, nuclear scintigraphy with various radionuclides, and MRI [20,31,33-37]. Recently, PET/CT has seen increasing application in the evaluation of suspected spine infection, particularly in the postoperative spine [38-45]. PET/MRI is undergoing preliminary investigation for possible use in spine infection [46]. 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 Suspected Spine Infection Although imaging studies have a role in the diagnostic evaluation of suspected spine infection, a high index of clinical suspicion for an infectious etiology is required in order to initiate the clinical workup [47].


Suspected Spine Infection PCAs

Suspected Spine Infection PCAs. Important laboratory parameters that may be assessed include serum erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), white blood cell (WBC) count with differential, and blood cultures [37,48-50]. Other testing such as for brucella or mycobacterium may be helpful if the patient is from the appropriate endemic area [2,4,5,7]. Because the imaging appearance of spine infection may overlap with other noninfectious pathologic entities, such as degenerative disc disease, inflammation, trauma, or neoplasm, spine biopsy with microbiologic and histopathologic analysis of the infected tissue is often required for diagnostic confirmation [35,51-58]. Special Imaging Considerations Although the clinical presentation and physical examination can help localize the level of suspected spine infection, in specific clinical situations it may be beneficial to image the entire spine [21,59]. This may be influenced by clinical presentation and patient factors such as a history of IV drug use, specific pathogens such as tuberculosis, or initial imaging findings that demonstrate multilevel spine involvement [21,59-61]. Like other spine infections, spinal epidural abscess has increased in incidence and is now seen in 2.5 to 3/10,000 patients [3,60]. Epidural abscess is often associated with diagnostic delay that can potentially lead to significant neurologic morbidity and mortality. Patients with preexisting risk factors, such as having a potential source for infection (preexisting infection, IV drug use, recent spine procedure) or a reason for being immunosuppressed (diabetes, steroid use) and patients with an elevated ESR, may be at increased risk for epidural abscess [18,21,22,62].


Suspected Spine Infection PCAs

Suspected Spine Infection PCAs. OR Discussion of Procedures by Variant Variant 1: Suspected spine infection (such as epidural abscess or discitis osteomyelitis), with new or worsening back or neck pain, with or without fever, who may have one or more of the following red flags (diabetes mellitus, IV drug use, cancer, HIV, or dialysis) or abnormal lab values. Initial imaging. The annual incidence of spine infection ranges from 4 to 24 per million per year [10]. In the presence of red flag conditions (diabetes mellitus, IV drug use, cancer, HIV, or dialysis) or abnormal lab values, imaging may be indicated if there is a clinical suspicion for spine infection in a patient with neck or back pain with or without fever. Clinically, it may be difficult to differentiate spine infection from other causes of neck or back pain such as degenerative disease, trauma, inflammatory spondyloarthropathy, or neoplastic involvement of the spine [3,35,55]. As any one of these clinical entities has the potential to mimic the imaging appearance of spine infection, it is important to use the combination of clinical presentation, laboratory values such as an elevated ESR and CRP and imaging findings in order to consider the diagnosis of spine infection [8]. The body regions covered in this clinical scenario are the 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. CT Spine Area of Interest As a result of its excellent delineation of osseous detail and greater sensitivity than radiography, CT can be used in the evaluation of spine infection [3]. The addition of IV contrast increases the conspicuity of paraspinal soft tissue abnormalities, such as inflammation or abscess that may be caused by infection.


Suspected Spine Infection PCAs

Suspected Spine Infection PCAs. In those cases in which a contrast- enhanced CT is to be performed, it is not necessary or useful to perform a noncontrast-enhanced CT first, because this latter examination does not add more diagnostic information. The sensitivity and specificity of CT for spine infection is 79% and 100%, respectively [33]. CT has low sensitivity (6%) for the identification of epidural abscess Suspected Spine Infection [33]. CT is often utilized to evaluate suspected spine infection when MRI is equivocal [3]. It is also of value in presurgical planning for patients with suspected infection-related spine instability, cord compression, as well as follow-up evaluation of the instrumented spine [30]. CT is often used to facilitate percutaneous image-guided spine biopsy [52,57]. Radiography Spine Area of Interest Radiography can be used as part of the initial evaluation in patients with suspected spine infection. Radiographs may not show any abnormalities during the early course of spine infection [3]. Imaging findings such as disc space narrowing, vertebral endplate erosion, and gross paraspinal soft tissue changes that can be seen on radiography lag behind the clinical course of spine infection by at least 2 to 8 weeks [3,10,31]. Nevertheless, the possible presence of one or more of these findings may increase the clinical suspicion for infection and may help guide subsequent imaging management. Radiographs, however, provide an overall view of the status and alignment of the vertebral column and can be used to assess for spinal instability [8]. 3-Phase Bone Scan Complete Spine A 3-phase bone scan with Tc-99m-methylene diphosphonate (MDP) has variable moderate-to-high sensitivity (81.4%) and low specificity (40.7%) for spine infection [31]. The advantages of skeletal scintigraphy include that it can be performed and completed in 1 day. Because of the imaging time required for a 3-phase bone scan, it tends to be utilized in select situations [3].


Suspected Spine Infection PCAs

Suspected Spine Infection PCAs. Gallium Scan Whole Body Ga-67 scintigraphy combined with single-photon emission computed tomography (SPECT) can be used to evaluate suspected spine infection. Ga-67 is less sensitive (73%) but more specific (61%) than skeletal scintigraphy [31]. The disadvantages of the gallium examination include a requirement for delayed images (24 to 72 hours). [31]. A Tc-99m-MDP study can be combined with Ga-67-citrate in order to improve the overall specificity of the examination (81%) while maintaining a sensitivity of 78% [31,36]. This combined examination may be utilized in select clinical situations such as when multifocal infection is suspected [3]. WBC Scan and Sulfur Colloid Scan Complete Spine A labeled leukocyte and sulfur colloid study is limited in the evaluation of spine infection as areas of infection often demonstrate decreased or absent radionuclide uptake [31]. Suspected Spine Infection Variant 2: Suspected spine infection (such as epidural abscess or discitis osteomyelitis), with recent intervention (such as surgery with or without hardware, pain injection, or stimulator implantation). Initial imaging. The mean incidence of postoperative instrumented spine infection is approximately 2% to 3% [40]. The diagnosis of postintervention spine infection is a clinical challenge given an overlap of clinical symptoms such as neck or back pain between postoperative and spine infection patients. The identification of abnormal laboratory parameters, such as leukocytosis or elevated ESR or CRP, may increase the clinical suspicion for spine infection in the postintervention patient [8,9]. The timing of the imaging examination with respect to when the spine intervention is performed is particularly important, because expected findings such as alteration of soft tissue and osseous structures, edema, and small paraspinal fluid collections such as seromas may represent the normal sequelae of an intervention shortly (a few days to weeks) after the procedure [28,29,48,69].


Suspected Spine Infection PCAs

Suspected Spine Infection PCAs. The body regions covered in this clinical scenario are the 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. CT Spine Area of Interest CT may be used to assess the spine for suspected infection, particularly following any surgical or interventional procedure, without or with spinal implants [3,30]. When initially considering the diagnosis of spine infection, it is important to use a combination of clinical presentation in the context of these red flags, abnormal laboratory values such as elevated ESR and CRP or leukocytosis, and abnormal imaging findings [8]. In the postoperative spine, CT may show implant loosening or malpositioning as well as malalignment and imaging findings that may be caused by infection. The addition of IV contrast increases the conspicuity of paraspinal soft tissue abnormalities, such as inflammation or abscess that may be caused by infection. In those cases in which a contrast-enhanced CT is to be performed, it is not necessary or useful to perform a noncontrast-enhanced CT first, because this latter examination does not add more diagnostic information. The sensitivity and specificity of CT for spine infection is 79% and 100%, respectively, but CT has low sensitivity (6%) for the identification of epidural abscess [33]. MRI Spine Area of Interest Because of its excellent tissue characterization and anatomic delineation, MRI without and with IV contrast has a sensitivity of 96% and a specificity of 94% for the evaluation of patients with suspected spine infection [3,7,14,16,24,37,51]. MRI without and with IV contrast is often utilized for the evaluation of patients who have undergone recent spine interventions and have suspected spine infection [3,7,14,16,24,37,51]. Artifact reduction techniques are often required in patients who have spinal instrumentation. MRI also provides optimal depiction of


Suspected Spine Infection PCAs

Suspected Spine Infection PCAs. Suspected Spine Infection Radiography Spine Area of Interest Radiographs are insensitive during the early course of spine infection [3]. In the subacute or chronic phase of infection, radiographs can be helpful in the follow-up evaluation of the posttreatment spine because serial radiographic studies may show new abnormalities such as implant loosening or alteration in spinal alignment that might be caused by infection [10]. 3-Phase Bone Scan A 3-phase bone scan with Tc-99m-MDP has variable moderate-to-high sensitivity (81.4%) and low specificity (40.7%) for spine infection [31]. Gallium Scan Whole Body Ga-67 scintigraphy combined with SPECT can be used to evaluate suspected spine infection in patients who have undergone recent spine interventions. Ga-67 is less sensitive (73%) but more specific (61%) than skeletal scintigraphy [31]. A dual Ga-67 and Tc-99m-MDP study can increase the overall specificity of the examination to 81% with a sensitivity of 73% [3,10,31,36]. This combined study can be used to assess the postoperative or postprocedure spine in cases of suspected spine infection when MRI imaging findings are equivocal [3,10]. WBC Scan and Sulfur Colloid Scan Complete Spine A labeled leukocyte and sulfur colloid study is limited in the evaluation of spine infection because areas of infection often demonstrate decreased or absent radionuclide uptake [31]. FDG-PET/CT Whole Body FDG-PET with CT has seen increasing application for the assessment of suspected spine infection in select cases as a complementary examination [10,31]. Increased FDG uptake is seen at sites of infection with an elevated SUVmax value. FDG-PET/CT can be used in the evaluation of the postsurgical or postprocedure spine for suspected infection when the MRI examination is inconclusive. Initial studies with FDG-PET/CT have shown the utility of this study in the initial evaluation of potentially infected spinal implants in selected patients [40].


Suspected Spine Infection PCAs

Suspected Spine Infection PCAs. Variant 3: Suspected spine infection (such as epidural abscess or discitis osteomyelitis), with new neurologic deficit or cauda equina syndrome. Initial imaging. The presence of a new neurologic deficit or cauda equina syndrome may be due to spinal cord or cauda equina compromise by either epidural abscess, displaced infected vertebral and/or disc material, or infection-mediated spinal malalignment or instability. The incidence of epidural abscess is 2.5 to 3 per 10,000 hospital admissions [14,60]. Although neurologic deficits are seen in 10% to 15% of cases of spine infection, these clinical situations require immediate imaging attention because the imaging evaluation helps to determine the location and extent of the spinal canal compromise [3,60]. The body regions covered in this clinical scenario are the 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. Suspected Spine Infection CT Spine Area of Interest Noncontrast and contrast-enhanced CT have an overall low sensitivity (6%) for the identification of epidural abscess [33]. Gross spinal cord compression with compromise of the spinal canal (>50% canal narrowing) may be seen in more advanced cases of spine infection [71]. The addition of IV contrast increases the conspicuity of paraspinal soft tissue abnormalities, such as inflammation or abscess that may be caused by infection. In those cases in which a contrast-enhanced CT is to be performed, it is not necessary or useful to perform a noncontrast-enhanced CT first, because this latter examination does not add more diagnostic information. The sensitivity and specificity of CT for spine infection is 79% and 100%, respectively [33]. CT with multiplanar reformations is often used in surgical planning and follow-up [8].


Suspected Spine Infection PCAs

Suspected Spine Infection PCAs. MRI Spine Area of Interest Because of its excellent tissue characterization and anatomic delineation, MRI without and with IV contrast has a sensitivity of 96% and a specificity of 94% for the evaluation of patients with suspected spine infection [3,7,14,16,24,37,51]. MRI also provides optimal depiction of the intraspinal contents including the epidural space and the spinal cord [6,17,18]. The use of MRI without and with IV contrast on an emergent or urgent basis, in patients with preexisting risk factors for possible spine infection and with an elevated ESR, may facilitate a more prompt diagnosis of spinal canal compromise by epidural abscess or other infected displaced structures. Epidural abscess is a feared complication of spine infection that may result in spinal cord and or cauda equina compression. The use of IV contrast helps to identify these abnormal epidural fluid collections, define their size and extent, and determine the presence of spinal cord and/or cauda equina compression [3]. MRI when performed without IV contrast may have utility, because it can show findings that are suggestive of possible spine infection, including marrow or paraspinal muscle edema, abnormal fluid collections, areas of abnormal signal, abnormality within the intervertebral disc, and adjacent vertebral endplates and gross structural abnormalities of the involved spine segment(s) [3,10,14,16,17,30,63-66,69]. MRI performed with IV contrast only is not considered to be useful because the precontrast MRI study is required for comparison in order to confirm areas of suspected abnormality within the spine segment(s) of interest. The presence and extent or the absence of contrast enhancement are important imaging features in suspected spinal infection and are best evaluated by comparing the pre- and postcontrast MRI examinations.


Suspected Spine Infection PCAs

Suspected Spine Infection PCAs. Radiography Spine Area of Interest Radiography is insensitive to the evaluation of the epidural space and to possible spinal cord compression and is therefore not useful as the initial imaging examination in patients presenting with neurologic compromise. As a complementary imaging study, radiography may help guide the imaging evaluation in those cases in which frank disc and vertebral body involvement by an infectious process is evident. Radiography can serve as a complementary test in order to assist with surgical management in those patients who may require surgical decompression and stabilization of the affected spinal segment [72]. 3-Phase Bone Scan There is no relevant literature regarding the use of bone scans in the initial imaging evaluation of a suspected spinal infection with a new neurologic deficit or cauda equina syndrome. WBC Scan and Sulfur Colloid Scan Complete Spine There is no relevant literature regarding the use of WBC scans in the initial imaging evaluation of a suspected spinal infection with a new neurologic deficit or cauda equina syndrome. Gallium Scan Whole Body There is no relevant literature regarding the use of gallium scans in the initial imaging evaluation of a suspected spinal infection with a new neurologic deficit or cauda equina syndrome. FDG-PET/CT Whole Body There is no relevant literature regarding the use of FDG-PET/CT in the initial imaging evaluation of a suspected spinal infection with a new neurologic deficit or cauda equina syndrome. Variant 4: Suspected spine infection (such as epidural abscess or discitis osteomyelitis), with decubitus ulcer or wound overlying spine. Initial imaging. Decubitus ulcers are often encountered at the level of the sacrum in chronically bedridden patients but may also be seen at other pressure sites along the back in immobile patients. When there is a clinical concern for possible spine infection extending from a decubitus ulcer or wound due to surgery or other causes [14], imaging may be necessary


Suspected Spine Infection PCAs

Suspected Spine Infection PCAs. Suspected Spine Infection for further evaluation of the involved spinal segment. Imaging can be utilized to distinguish between superficial infection or cellulitis and deeper infections including osteomyelitis and paraspinal or epidural abscess formation [31,48]. The body regions covered in this clinical scenario are the cervical, thoracic, lumbar spine, and sacrum. These body regions might be evaluated separately or in combination as guided by physical examination findings, patient history, and other available information. CT Spine Area of Interest As a result of its excellent delineation of osseous detail and greater sensitivity than radiography, CT can be used in the evaluation of suspected osteomyelitis as a complication from a decubitus ulcer or wound overlying the spine [3]. The addition of IV contrast increases the conspicuity of paraspinal soft tissue abnormalities, such as inflammation or abscess that may be caused by infection. In those cases in which a contrast-enhanced CT is to be performed, it is not necessary or useful to perform a noncontrast-enhanced CT first, because this latter examination does not add more diagnostic information. The sensitivity and specificity of CT for spine infection is 79% and 100%, respectively [33]. CT may be used to assess the spine for suspected infection following any surgical or interventional procedure [3,30]. MRI Spine Area of Interest Because of its excellent tissue characterization and anatomic delineation, MRI without and with IV contrast can be utilized for the evaluation of patients with suspected spine infection at the site of a decubitus ulcer or wound [3,7,14,16,24,37,51]. The sensitivity and specificity of MRI for spine infection is 96% and 94%, respectively [14].


Suspected Spine Infection PCAs

Suspected Spine Infection PCAs. The use of IV contrast not only increases lesion conspicuity, characterized by foci of abnormal soft tissue enhancement and peripherally enhancing fluid collections within and/or surrounding the affected spinal segment, but also helps to define the extent of the infectious process [3]. MRI is also used to help distinguish expected postoperative changes at the surgical skin site from infection and contrast-enhanced MRI can be used to assess postoperative fluid collections for suspected infection [28,29,69,70]. MRI when performed without IV contrast may have utility, because it can show findings that are suggestive of possible spine infection, including marrow or paraspinal muscle edema, abnormal fluid collections, areas of abnormal signal, abnormality within the intervertebral disc, and adjacent vertebral endplates and gross structural abnormalities of the involved spine segment(s) [3,10,14,16,17,30,63-66,69]. MRI performed with IV contrast only is not considered to be useful because the precontrast MRI study is required for comparison in order to confirm areas of suspected abnormality within the spine segment(s) of interest. The presence and extent or the absence of contrast enhancement are important imaging features in suspected spinal infection and are best evaluated by comparing the pre- and postcontrast MRI examinations. Radiography Spine Area of Interest Radiography provides a quick survey of the soft tissues and underlying osseous structures at the site of suspected spine infection when either a decubitus ulcer or wound is present [3]. Radiography can be used to tailor a subsequent cross-sectional imaging examination especially in patients with prior spine surgery or interventions [8]. 3-Phase Bone Scan A 3-phase bone scan with Tc-99m-MDP has variable moderate-to-high sensitivity (81.4%) and low specificity (40.7%) for suspected spine infection with decubitus ulcer or wound overlying the spine [31].


Suspected Spine Infection PCAs

Suspected Spine Infection PCAs. Gallium Scan Whole Body Ga-67 scintigraphy combined with SPECT can be used to evaluate suspected infection involving a decubitus ulcer or wound overlying the spine. Ga-67 is less sensitive (73%) but more specific (61%) than skeletal scintigraphy [31]. The disadvantages of the gallium examination include a requirement for delayed images (24 to 72 hours) [31]. A dual Ga-67 and Tc-99m-MDP examination has a similar sensitivity (73%) and an increased specificity (81%) [31]. This combined examination may be utilized in select clinical situations such as when spine infection is suspected adjacent to a decubitus ulcer or wound [31]. WBC Scan and Sulfur Colloid Scan Complete Spine A labeled leukocyte and sulfur colloid study is limited in the evaluation of spine infection because areas of infection often demonstrate decreased or absent radionuclide uptake [31]. Suspected Spine Infection FDG-PET/CT Whole Body FDG-PET with CT has seen increasing application for the assessment of suspected spine infection in select cases as a complementary examination [10,31]. Increased FDG uptake is seen at sites of infection with an elevated SUVmax value. FDG-PET/CT can be used in the evaluation of the postsurgical spine for suspected infection of the skin wound when MRI is inconclusive. Variant 5: Suspected spine infection (such as epidural abscess or discitis osteomyelitis). Abnormal radiographs or CT findings. Next imaging study. When an imaging study such as a radiograph or CT of the spine raises a concern for possible spine infection, additional imaging may be required. Because there are other pathologic entities, such as degenerative, traumatic, or inflammatory spondyloarthropathy, which can simulate spine infection on the initial radiographs or CT images, additional imaging is used in conjunction with the clinical evaluation in order to make the appropriate diagnosis [55]. The body regions covered in this clinical scenario are the cervical, thoracic, and lumbar spine.


Suspected Spine Infection PCAs

Suspected Spine Infection PCAs. 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. MRI Spine Area of Interest Because of its excellent tissue characterization and anatomic delineation, MRI without and with IV contrast is often utilized for the evaluation of patients with suspected spine infection [3,7,14,16,24,37,51]. MRI without and with IV contrast has a sensitivity of 96% and a specificity of 94% for the evaluation of patients with suspected spine infection [3,7,14,16,24,37,51]. MRI also provides optimal depiction of the intraspinal contents, including the epidural space and the spinal cord [6,17,18]. The use of IV contrast increases lesion conspicuity, characterized by foci of abnormal soft tissue enhancement and peripherally enhancing fluid collections within and/or surrounding the affected spinal segment, and also helps to define the extent of the infectious process [3]. MRI can be performed as the next imaging study when the initial radiographs and/or CT examination show abnormal findings that may be indicative of spine infection. MRI when performed without IV contrast may have utility, because it can show findings that are suggestive of possible spine infection, including marrow or paraspinal muscle edema, abnormal fluid collections, areas of abnormal signal, abnormality within the intervertebral disc, and adjacent vertebral endplates and gross structural abnormalities of the involved spine segment(s) [3,10,14,16,17,30,63-66,69]. MRI performed with IV contrast only is not considered to be useful because the precontrast MRI study is required for comparison in order to confirm areas of suspected abnormality within the spine segment(s) of interest. The presence and extent or the absence of contrast enhancement are important imaging features in suspected spinal infection and are best evaluated by comparing the pre- and postcontrast MRI examinations.


Clinically Suspected Vascular Malformation of the Extremities.  Introduction/Background Vascular anomalies encompass a broad range of pathologies histologically composed of vascular type cells. These lesions are most commonly classified by the International Society for the Study of Vascular Anomalies according to their underlying histology as either vascular malformations or vascular tumors. Vascular malformations represent focal structural abnormalities of the vascular tree, typically related to developmental errors during vasculogenesis [1], whereas, vascular tumors are caused by neoplastic cellular proliferation of the endothelium [1]. The extremities are the most common site of these vascular lesions outside of the head and neck [1,2]. Vascular malformations more commonly represent isolated spontaneous lesions yet can be part of one of several syndromes such as Parkes Weber syndrome [1,3]. These typically grow commensurate with patient age, often in conjunction with hormonal changes, such as puberty and pregnancy [3-6]. Therefore, vascular malformations that are present at birth may not present clinically until adolescence or adulthood. These lesions can be broadly divided into high- and low-flow lesions. High-flow malformations include arteriovenous malformations and arteriovenous fistulas, both of which demonstrate arterial flow and arteriovenous shunting. The former tend to be congenital lesions, and the latter are typically acquired as sequela of prior trauma or surgery. High-flow lesions comprise approximately 10% of peripheral vascular malformations and may present with pain, skin discoloration, warmth, or mass with palpable thrill or bruit [6]. Compression neuropathy, soft-tissue ulceration, bleeding, arterial steal phenomenon, and high-output cardiac failure may be seen in extreme cases [4,7]. Low-flow lesions include capillary, venous, and lymphatic malformations and are overall more common than high-flow lesions.


Clinically Suspected Vascular Malformation of the Extremities. Of these, capillary malformations are the most common but rarely require imaging for diagnosis because of their characteristic cutaneous manifestations [3,4]. Venous and lymphatic malformations have a reported prevalence of 1% in the general population with 40% involving the extremities [6]. Although symptomatology is variable, these lesions may present with focal or more generalized extremity pain, swelling, or compressible mass with or without associated skin discoloration. Involvement of the deep tissues, including bone, is not uncommon, and physical examination often underestimates their full extent [2,5]. Vascular tumors are subclassified based on propensity for aggressive and malignant behavior; however, the majority are benign [3]. Infantile hemangiomas are among the most common type of vascular neoplasm. These benign lesions present in infancy or early childhood and demonstrate rapid proliferative growth followed by eventual involution, most often not requiring treatment [7]. Less commonly, vascular tumors such as the intramuscular hemangioma, can present in adulthood with swelling, pain, or mass. The diagnosis of a vascular malformation or neoplasm is frequently made clinically when classic signs and symptoms are present. Imaging is used for confirmation, particularly if the clinical presentation is atypical or vague [3,8] and is generally required for characterization of these lesions. Imaging also plays a critical role in treatment planning, which is often required because of growth, limb deformity, and decreased function, as well as pain. Lesion characteristics such as subtype (high flow versus low flow), depth, and invasion of adjacent structures, as well as inflow and outflow vessels, help in optimal treatment selection [9]. Treatment approach spans the spectrum of conservative to aggressive options, which include compression dressings, sclerotherapy,


Clinically Suspected Vascular Malformation of the Extremities. 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 Vascular Malformation of the Extremities transarterial or transvenous embolization, and surgical resection. Sclerotherapy is often used for low-flow lesions, whereas high-flow lesions are most effectively treated with embolization [8,10]. All elements are essential: 1) timing, 2) reconstructions/reformats, and 3) 3-D renderings. Standard CTs with contrast also include timing issues and recons/reformats. Only in CTA, however, is 3-D rendering a required element. This corresponds to the definitions that the CMS has applied to the Current Procedural Terminology codes. Discussion of Procedures by Variant Variant 1: Upper or lower extremity. Suspected vascular malformation presenting with pain or findings of physical deformity including soft-tissue mass, diffuse or focal enlargement, discoloration, or ulceration. Initial imaging. The body regions covered in this clinical scenario are shoulder, humerus, elbow, forearm, wrist, hand, hip, femur, knee, tibia/fibula, ankle, and foot. Radiography Extremity Radiographs are often used as the initial imaging modality in the workup of a patient presenting with nonspecific extremity complaints and may be useful for the exclusion of more common causes of extremity pain and deformity. However, radiographs are of limited utility for the specific purpose of vascular malformation imaging. In the setting of a vascular malformation, radiographs may be normal or show a soft-tissue mass [5,12].


Clinically Suspected Vascular Malformation of the Extremities. Phleboliths may also be seen and provide a clue to the diagnosis of venous malformations and hemangiomas, which are reported to contain phleboliths in 20% to 67% of cases [3,12]. Lesions located adjacent to bone may be associated with bone changes, including periosteal reaction, remodeling, or signs of destruction, such as cortical scalloping and lucencies. Although such findings may be visible radiographically, they are not specific for the diagnosis of vascular malformations [6,12]. US Duplex Doppler Extremity Ultrasound (US) with duplex Doppler imaging can be useful for the initial assessment of suspected vascular malformation, particularly if a focal mass or other targetable superficial symptomatology is present. US with Doppler can differentiate high-flow from low-flow malformations, and often provides a specific diagnosis in cases where characteristic vascular malformation features are present [3,5,13,14]. US may also be diagnostic of other lesions within the differential diagnosis for nonspecific extremity complaints [3,15]. Ultimately, this modality is limited in regards to tissue penetration and a small imaging field of view, which may lead to suboptimal evaluation of lesion extent and size, particularly if located deep in the extremity or adjacent to bone [2,8,13]. As a result, cross-sectional imaging, such as MRI, may be needed for more complete evaluation and definitive diagnosis [1,3,13], especially in cases without a targetable focal abnormality. US Extremity Area of Interest with IV Contrast There is limited evidence regarding the utility of contrast-enhanced US (CEUS) in evaluating suspected peripheral vascular malformations, but this modality may be considered in select cases. The addition of microbubble contrast may enhance visualization of small arteriovenous shunts and low-flow vessels compared with US with Doppler [16].


Clinically Suspected Vascular Malformation of the Extremities. CEUS also has potential for quantifying perfusion in vascular malformations, which could be helpful in assessing treatment response [17]. CT Extremity CT offers the benefit of high spatial resolution and provides comprehensive anatomic detail in the workup of extremity complaints. For the specific purpose of vascular malformation imaging, CT may reveal a soft-tissue mass with or without phleboliths, as well as provide information about size and lesion extent [12]. Bone involvement and acute complications like hemorrhage can also be assessed with CT [3,6]. Intravenous (IV) Vascular Malformation of the Extremities contrast administration improves lesion delineation and allows for the assessment of enhancement patterns, which may help narrow the differential diagnosis of a focal finding [3]. However, in general, MRI is the preferred imaging modality when evaluating suspected vascular malformations that are due to its greater soft-tissue contrast and ability to obtain dynamic flow information with MR angiography (MRA) [10]. CTA Extremity CTA with IV contrast can be used to evaluate a suspected vascular malformation. It is generally of greater utility for a high-flow lesion, such as an arteriovenous malformation, as CTA is capable of delineating the feeding arteries, nidus, and draining veins, which typically characterize these lesions [10]. CTA may also provide some information in regards to lesion extent and invasion into muscular compartments and bones [10]. However, MRI or MRA is the preferred method for suspected vascular malformation imaging that is due to superior soft-tissue contrast and potential for dynamic blood flow imaging [2,10,18]. MRI Extremity MRI offers superior soft-tissue contrast compared with CT and plays an important role in the workup of suspected vascular malformations and soft-tissue masses. Lesion morphology and internal signal characteristics can be assessed, often allowing for definitive diagnosis [2-4,6,7,9,19].


Clinically Suspected Vascular Malformation of the Extremities. MRI accurately determines lesion extent and involvement of surrounding structures, both of which are underestimated clinically in up to 76% of cases [2,5,7]. Contrast-enhanced sequences may not be necessary if typical features, such as flow voids, are present; however, the use of IV contrast is preferred for improved specificity and more complete characterization [3,6,8,20]. IV contrast also allows better visualization of the feeding and draining vessels in high-flow lesions, although this is best performed using an MRA protocol [1-3,6,7,21]. Additionally, MRI is useful for the evaluation of other soft- tissue lesions and musculoskeletal pathologies that might be considered in the differential diagnosis for a mass, enlarged extremity, or pain [19,20,22,23]. MRA Extremity MRA is an excellent imaging option when a vascular malformation is suspected. The typical MRA protocol includes conventional T1 and T2 sequences, which provide anatomic information including lesion size, extent, and internal morphology [6,7]. Dynamic contrast-enhanced MRA, when combined with conventional MRI, has a reported sensitivity of 83% and specificity of 95% for the differentiation of venous and nonvenous malformations [24]. Time-resolved MRA has been shown to be nearly equivalent to arteriography for evaluating dynamic perfusion, allowing for accurate differentiation of feeding arteries and draining veins in high-flow lesions [2,9]. MRA can also be useful in differentiating vascular malformations from other causes of an extremity mass, such as soft-tissue neoplasms, although there may be some overlap in findings [7]. Although noncontrast time-of-flight techniques can be employed, contrast-enhanced MRA is preferred for improved depiction of smaller vessels and dynamic imaging assessment [6,25]. Arteriography Extremity There is no evidence to support the use of arteriography as the initial imaging evaluation for a suspected vascular malformation because of its invasive nature.


Clinically Suspected Vascular Malformation of the Extremities. MRA is noninvasive and can depict the vascular anatomy of a malformation nearly as well as arteriography [9], making it the preferred initial imaging evaluation. Arteriography does offer the highest resolution imaging of small vessels and superior temporal resolution for assessment of flow dynamics. These advantages may be useful for high-flow lesions when MRA findings are equivocal or when treatment planning requires the highest available vascular detail resolution and/or better estimation of intralesional shunting [5-8]. Variant 2: Upper or lower extremity. Vascular murmur (bruit or thrill). Initial imaging. The body regions covered in this clinical scenario are shoulder, humerus, elbow, forearm, wrist, hand, hip, femur, knee, tibia/fibula, ankle, and foot. Radiography Extremity Radiographs are of limited benefit for the specific purpose of vascular malformation imaging, especially in regard to lesions presenting with a vascular murmur. Radiographs may be normal or show a soft-tissue mass [5,12]. Venous malformations and hemangiomas may contain radiographically visible phleboliths in 20% to 67% of cases, which provide a clue to the diagnosis; however, these lesions typically do not present with a vascular murmur [3,12]. Lesions located adjacent to bone may be associated with bone changes, such as periosteal reaction, remodeling, or signs of destruction, such as cortical scalloping and lucencies. Although such findings may be visible radiographically, they are not specific for the diagnosis of vascular malformations [6,12]. Vascular Malformation of the Extremities US Duplex Doppler Extremity US is fast and can often provide initial imaging characterization of vascular malformations [5-7,13]. The presence of a vascular murmur is clinically suggestive of a high-flow malformation, and US with Doppler imaging is generally regarded as a good initial option for the confirmation of a high-flow component.


Clinically Suspected Vascular Malformation of the Extremities. In many cases, US can help differentiate between the various types of vascular malformations and other soft-tissue lesions [5,7,13-15]. However, US has limitations in regard to field of view and tissue penetration that typically limits the ability to completely characterize and delineate the full extent of vascular malformations. Additional cross-sectional imaging, such as MRI, is usually needed for complete characterization [2,8,9]. US Extremity Area of Interest with IV Contrast Limited evidence is available regarding the utility of CEUS specifically for the evaluation of peripheral vascular malformations, but this may be considered in select cases. Visualization of small arteriovenous shunts may be improved with CEUS compared with US with Doppler [16]. The potential for quantifying perfusion in vascular malformations with CEUS could also be useful in assessing treatment response [17]. CTA Extremity CTA features comparatively high spatial resolution, which allows for the characterization of a vascular nidus, enlarged feeding arteries, and draining veins that are frequently encountered in high-flow lesions that often present clinically with a vascular murmur [10]. CTA may also be useful for the assessment of other vascular- related pathologies, such as vasculitis and compression syndromes [10]. However, poor soft-tissue contrast and limited temporal resolution are drawbacks to this modality, and MRA is typically preferred over CTA [10,18]. MRI Extremity The high tissue contrast of MRI makes it a preferred modality to assess the extent and distribution of vascular malformations, which are often underestimated by physical examination alone [2,5]. MRI is also a good option to evaluate for other soft-tissue lesions that may be included within a differential diagnosis of bruit on clinical examination [19,23]. The use of IV contrast improves lesion characterization and optimizes visualization of the surrounding anatomy [3,6,20].


Clinically Suspected Vascular Malformation of the Extremities. Although MRI is generally considered high yield for evaluating lesion extent and often can distinguish between the various types of vascular malformations and soft-tissues masses, its evaluation of flow dynamics and intralesional vascular anatomy is limited when compared with MRA [3]. MRA Extremity MRA has emerged as the preferred modality for assessing vascular malformations, particularly in patients with a vascular murmur and suspected high-flow malformation, due to its exceptional ability to delineate inflow and outflow anatomy noninvasively. Time-resolved MRA has been reported to rival conventional angiography for the portrayal of both functional flow dynamics and anatomic detail [9]. Combined conventional and dynamic contrast-enhanced MRA has a reported sensitivity of 83% and specificity of 95% for the differentiation of venous and nonvenous malformations [24]. Furthermore, MRA protocols typically include conventional high soft-tissue contrast T1 and T2 sequences which accurately assess the internal characteristics and extent of vascular malformations. This modality can also assess for and characterize other possible soft-tissue masses which may be included in the clinical differential diagnosis [6,7]. One potential weakness of time-resolved MRA is its underestimation of shunt volumes in vascular malformations which may be better evaluated with arteriography [7]. Arteriography Extremity Arteriography offers high temporal and spatial resolution images of the vascular anatomy associated with high- flow lesions such as arteriovenous malformations, including the inflow and outflow vessels as well as intralesional shunting [5,7]. Although the presence of a vascular murmur increases the suspicion of a high-flow Supporting Documents The evidence table, literature search, and appendix for this topic are available at https://acsearch. acr.org/list.


Headache Child PCAs

Headache Child PCAs.  Introduction/Background Headache is a common complaint, even in early childhood. The prevalence of headaches increases with age and ranges from 37% to 51% for children 7 years of age and gradually increases to 57% to 82% by 15 years of age [1]. Prepubertal boys were found to commonly experience more headaches than girls, whereas after puberty, girls were more affected [2]. Headaches can be either primary or secondary in nature. Primary headaches result from the headache condition itself and not from another cause. A secondary headache is a headache that is present because of another condition. Diagnosis of primary headache disorders of children rests principally on clinical criteria as defined by the International Headache Society [3]. The evaluation of a child with headache begins with acquiring a thorough medical history and performing a physical examination with measurement of vital signs, including blood pressure, a complete neurologic examination, and examination of the optic discs. Secondary headache is more common in younger children [7,8]. Most of the secondary headaches have benign etiologies. A single episode of acute headache usually results from an acute infection ranging from viral upper respiratory illness to acute meningitis. Chronic progressive headaches often indicate a serious underlying abnormality, such as a brain tumor, and children with abnormal neurological findings should undergo neuroimaging. The clinical experiences of primary care physicians, pediatricians, and neurologists indicate that neuroimaging studies have a limited role in children with primary headaches [1]. The high prevalence of headaches and the low yield of imaging in pediatric patients presenting with headaches alone bring into question the value of screening for patients with primary headaches. Pediatric headache literature has repeatedly reported that the value of neuroimaging in children with headache is generally low [9-12].


Headache Child PCAs

Headache Child PCAs. In a study by Yilmaz et al [12] of 449 children with headache, approximately 55% of children had migraine, 30% had tension-type headaches, 10% had secondary headaches, and 5% were unspecified. Twenty-one percent of imaged children (n = 324) had abnormalities identified on their magnetic resonance imaging (MRI) examinations, largely incidental findings, with <1% having relevant findings to explain the headache, namely tumor with hydrocephalus. Similarly, Martens et al [11] found that even though some neurological signs were present in a substantial number of children with primary headaches, mostly migraines, the yield of brain MRI scans was still low. Therefore, the yield of brain MRI is not contributory to the diagnostic and therapeutic approach in children with primary headaches. Based on analysis of a large body of evidence, the practice parameters authored by the American Academy of Neurology and Child Neurology Society recommend considering neuroimaging in children with an abnormal neurologic examination (eg, focal findings, signs of increased intracranial pressure, significant alteration of Reprint requests to: publications@acr.org Advanced imaging modalities such as computed tomography (CT) and MRI are preferred when neuroimaging in children is considered. CT exposes children to radiation, whereas MRI sometimes requires sedation or general anesthesia, especially in children <6 years of age. Therefore, neuroimaging should be reserved for children with a suspicious clinical history, abnormal neurological findings, or other physical signs suggestive of significant intracranial pathology [7,9]. CT In most cases, CT is usually not the study of choice for imaging children with headaches. However, there are some cases when a CT scan of the head is indicated because of its speed and sensitivity for detecting acute blood products.


Headache Child PCAs

Headache Child PCAs. In the emergency setting, if a brain tumor is suspected, CT without IV contrast can be performed initially; however, a contrast-enhanced study may be indicated if it is not possible to perform an MRI scan of the brain. In patients with thunderclap headache, subarachnoid hemorrhage (SAH) from a ruptured aneurysm or arteriovenous malformation must be excluded; therefore, a noncontrast CT scan of the head is the imaging modality of choice as it is superior to MRI in detecting acute SAH [20]. If subarachnoid or parenchymal hemorrhage is detected, further evaluation for aneurysm or vascular malformation must be performed. This evaluation can be accomplished by CT angiography (CTA), conventional arteriography, or MR angiography (MRA) [21,22]. MRV MR venography (MRV) is the study of choice in children with suspected venous outflow stenosis, such as those with pseudotumor cerebri, or those with venous sinus thrombosis, such as mastoiditis. MRV can be performed with or without IV contrast. MRV with contrast can be helpful in the detection of intracranial sinovenous stenosis that can go undetected because of artifactual flow voids in the transverse sinuses on traditional noncontrast (time- of-flight) MRV [24]. CTV If MRV is not possible, or in cases in which the results of MRV are ambiguous, imaging with contrast-enhanced CT venography (CTV) has been found to be a fast, widely accessible alternative approach with high sensitivity and specificity in detecting venous sinus thrombosis [25]. MRV is generally preferred over CTV because of radiation concerns. MRA If subarachnoid or parenchymal hemorrhage is detected, further evaluation for aneurysm or vascular malformation must be performed. This evaluation can be accomplished by MRA, CTA, or conventional arteriography [21,22]. MRA can be performed without IV contrast and is easily added to a standard MRI study if a stroke or hemorrhage is detected.


Headache Child PCAs

Headache Child PCAs. If there is strong concern for arterial dissection within the head and/or neck, the diagnosis is generally made by MRI or MRA [26]. Arteriography In children with sudden onset of severe headache and a positive MRI or CT study demonstrating intracranial hemorrhage or stroke, digital subtraction arteriography can be performed. Arteriography is an invasive procedure that requires a skilled angiographer to be available emergently. Discussion of Procedures by Variant Variant 1: Child. Primary headache. Initial imaging. Radiography There is no role for radiography in patients with primary headache. MRI In a study by Yilmaz et al [12] of 449 children with headache, approximately 55% of children had migraine, 30% had tension-type headaches, 10% had secondary headaches, and 5% were unspecified. Twenty-one percent of imaged children (n = 324) had abnormalities identified on their MRI examinations, largely incidental findings, with <1% having relevant findings to explain the headache, namely tumor with hydrocephalus. Similarly, Martens et al [11] found that despite findings on neurological/physical examinations in a substantial number of children with headaches, mostly migraines, the yield of brain MRI scans was low. Therefore, the yield of brain MRI is not contributory to the diagnostic and therapeutic approach. In unusual circumstances when a complete physical examination is not possible or a thorough history is not available MRI could be considered. CTA There is no role for CTA in patients with primary headache and no concerning findings on clinical or physical examination. CTV There is no role for CTV in patients with primary headache and no concerning findings on clinical or physical examination. MRA There is no role for MRA in patients with primary headache and no concerning findings on clinical or physical examination. MRV There is no role for MRV in patients with primary headache and no concerning findings on clinical or physical examination.


Headache Child PCAs

Headache Child PCAs. The use of contrast in MRV depends on institutional preferences. Arteriography There is no role for arteriography in patients with primary headache and no concerning findings on clinical or physical examination. Another diagnosis to consider in patients with headache and papilledema is pseudotumor cerebri, also known as pseudotumor cerebri syndrome (PTCS). Primary PTCS is also known as idiopathic intracranial hypertension. This disorder typically manifests as severe headaches and visual impairments and prevails in overweight females of childbearing age but can occur in obese males and prepubertal thin girls and boys. Its incidence is rising in parallel with the obesity epidemic. The etiology of pseudotumor cerebri is unclear, with impaired cerebrospinal fluid (CSF) homeostasis and altered venous hemodynamics the proposed mechanisms for elevated intracranial pressure. A study by Alperin et al [33] supported these mechanisms by demonstrating a reduced relative cerebral drainage through the internal jugular vein with an increased intracranial CSF volume that accumulates in the subarachnoid space. Secondary PTCS is a result of cerebral venous abnormalities such as thrombosis, medications such as vitamin A, and medical disorders such as endocrinopathies [34]. In cases of suspected PTCS, MRI of the brain with and without contrast should be performed as MRI is more sensitive for detection of secondary signs of increased intracranial pressure such as an empty sella, dilated optic sheaths, tortuous or enhancing optic nerves, and flattening of the posterior aspects of the globes. MRI reveals more details of the intracranial structures without radiation and is better able to evaluate for meningeal infiltration and isodense tumors over CT. In patients without PTCS, MRI should reveal normal brain parenchyma without evidence of hydrocephalus, mass, or structural lesion and no abnormal meningeal enhancement.


Headache Child PCAs

Headache Child PCAs. It is important to note that meningeal enhancement can be seen on MRI following lumbar puncture and should not be confused with pathology. Imaging of the orbits including a coronal, fat-saturated T2-weighted sequence is recommended to better evaluate for dilatation of the optic sheaths [24]. In patients in whom there is high suspicion for Chiari I deformity, a noncontrast MRI scan of the brain to include a sagittal T2-weighted sequence of the craniocervical junction with optional phase-contrast CSF flow study at the craniocervical junction is the study of choice. The Chiari I deformity is a condition characterized by the herniation of the cerebellar tonsils through the foramen magnum with headache as its most common symptom in older children [35,36]. In children <3 years of age, abnormal oropharyngeal function is commonly demonstrated. In children >3 years of age, scoliosis (associated with syringohydromyelia) or headache worsened by the Valsalva maneuver are typical findings. Most literature agrees that occipital headache in children is rare and calls for diagnostic caution; however, isolated occipital and cervical pain are not characteristic symptoms of any headache group in the pediatric age group, and their presence or absence does not correspond to changes on conventional brain MRI [37]. Children with sickle cell anemia are a special subgroup of patients who require particular attention as recurrent headaches and migraines in these children are common and undertreated [17]. Low hemoglobin levels and high pain rates are associated with recurrent headaches and migraines, whereas silent cerebral infarction is not. However, acute headache in children with sickle cell anemia is more frequently associated with acute central nervous system events than in the general pediatric population, so the threshold to image these patients should be lower.


Headache Child PCAs

Headache Child PCAs. These children are at risk for posterior reversible encephalopathy syndrome, especially after a bone marrow transplant, and for SAH, especially in the setting of arterial aneurysm. A history of stroke, transient ischemic attack, seizures, neurological symptoms, focal neurological examination, or elevated platelet counts at presentation warrants confirmatory imaging studies [38]. MRI is the imaging modality of choice in these children because of its superior sensitivity for infarction and other parenchymal abnormalities. Seizures are one of the most common secondary etiologies for headache and often have auras similar to some migraines [39]. MRI without IV contrast is indicated in the evaluation of patients with seizures. CTA If an acute stroke is suspected, CTA in conjunction with a noncontrast CT scan of the head is indicated, with MRI/MRA the preferred modality because of its greater sensitivity in detecting acute stroke versus CT. CT should not be delayed if MRI is not available or feasible. CTA of the head and neck are usually indicated if there is strong suspicion for arterial dissection. If MRA is performed initially to evaluate for arterial dissection and is inconclusive, CTA may be helpful for further evaluation. CTV If there is concern for venous outflow obstruction, such as in the setting of venous sinus thrombosis or PTCS, CTV has been found to be an alternative approach with high sensitivity and specificity in detecting venous sinus thrombosis compared with MRV [25]. MRV remains the imaging study of choice over CTV in children. MRA MRI is more sensitive for detecting early changes of a stroke, and a concurrent MRA plays an important role in stroke imaging. MRA is indicated for children with sickle cell anemia in the setting of headache. MRV In conjunction with MRI, MRV is indicated in patients with possible venous sinus abnormalities, such as those with suspected PTCS. Decreased spinal canal compliance has been identified in patients with PTCS [40].


Headache Child PCAs

Headache Child PCAs. A study by Dwyer et al [41] that reviewed more than 200 MRVs in suspected cases of pseudotumor cerebri found that 52% of scans showed evidence of venous obstruction in the dominant side of venous circulation. This was statistically higher than in control groups. It is important to note that reversibility of venous outflow obstruction can be seen on MRV in these patients following lumbar puncture, which argues that the presence of venous outflow obstruction could be secondary to the increased intracranial pressure itself [42]. When cerebellar tonsillar ectopia of >5 mm is identified, imaging and clinical consideration of PTCS are warranted to avoid misdiagnosis as Chiari I [43]. In addition to the initial MRV in patients with suspected PTCS, a second MRV following CSF drainage may be helpful. Venous sinus occlusion and arteriovenous fistulas may produce PTCS. MRV is indicated when there is concern for venous sinus thrombosis, especially in children with intracranial extension of infection. Children with mastoiditis are at a particularly high risk for venous sinus thrombosis. Girls using oral contraceptives are also at increased risk for thrombosis. The use of contrast in MRV depends on institutional preferences. Contrast-enhanced MRV may be helpful when evaluating areas such as the sigmoid venous sinuses, a location often degraded by artifact on noncontrast MRVs. Arteriography In patients with evidence for stroke on CT or MRA, arteriography may be helpful for further evaluation, especially when intervention such as thrombolysis or treatment of vascular malformations is considered. Arteriography is also more sensitive in detecting small vessel disease and arterial dissection and may be a useful examination if results of MRA or CTA are unclear and there is strong suspicion for such. Variant 3: Child. Sudden severe headache (thunderclap headache). Initial imaging. Radiography There is no role for radiography in children with sudden severe headache.


Headache Child PCAs

Headache Child PCAs. Severe sudden headaches can be associated with SAH and intracranial hemorrhage that may occur with aneurysms or other vascular malformations, such as AVMs and cavernomas. Neuroimaging of children with severe or unusual head pain who have a first-degree relative with an aneurysm or other vascular abnormality is indicated, as these vascular pathologies can be familial but are otherwise uncommon [39]. The cornerstone for the diagnosis of SAH is a noncontrast CT scan; however, the use of MRI techniques such as proton-density-weighted imaging, susceptibility-weighted imaging (SWI)/gradient-recalled echo (GRE) imaging, or T2-weighted fluid- attenuated inversion recovery (FLAIR) imaging improves the diagnosis of acute SAH, as conventional sequences are insensitive to the finding [21]. A study by Mitchell et al [49] found that sensitivity to SAH varied among MR sequence from 50% to 94% in acute SAH and from 33% to 100% in subacute SAH. The most sensitive sequences were FLAIR and SWI/GRE. It is important to note that signal in the sulci on the FLAIR sequence can be artifactually increased in children receiving propofol and supplemental oxygenation and can mimic SAH. Meningitis can also give this appearance. CT In the acute setting, noncontrast CT is indicated in the evaluation of acute thunderclap headache. The sensitivity of CT for the detection of acute SAH is greater than MRI at 98% with a specificity of 99% [50]. CT is often the initial imaging study of choice because of availability and lack of need for sedation. CTV Except in cases of thunderclap headache related to an AVM, CTV is usually not indicated in patients with thunderclap headache. MRV Except in cases of thunderclap headache related to an AVM, MRV is usually not indicated in patients with thunderclap headache. The use of contrast in MRV depends on institutional preferences.


Headache Child PCAs

Headache Child PCAs. Arteriography As an invasive and often unavailable study, arteriography is rarely the initial angiographic evaluation performed in children with thunderclap headache. A study in 2011 by Sabri et al [47] evaluated patients that presented with intracranial hemorrhage, predominantly SAH. Their findings showed that the yield from CTA and arteriography are relatively comparable, but that arteriography is superior in detection of aneurysm. Hence, in cases in which the CTA result was found to be normal despite high suspicion for lesion in the setting of SAH, a follow-up CTA or arteriography is considered useful. However, use of CTA over arteriography has been controversial. In 2007, Kallmes et al [45] declared that because both negative and positive CTA scans mandate subsequent conventional angiography, the CTA should be dispensed with and patients should proceed directly to arteriography. Furthermore, Moran et al [46] declared that conventional angiography with arteriography is the ideal method for imaging these patients because of its ability to detect aneurysms quickly, reliably, and safely and that it guides the prompt proper therapy. The applicability of these adult-based studies to the pediatric population is debatable. MRI In a study by Lateef et al [1], the overwhelming majority of acute headaches in children and adolescents were attributable to common, minor, transient conditions, such as upper respiratory illness. Headache is the most common symptom identified with the intracranial spread of infection resulting from dural irritation and localized encephalitis. The headache can be attributed to either intracranial or extracranial infections. In the setting of suspected intracranial infection, the need for neuroimaging is guided by laboratory tests and clinical signs [51]. Clinical signs suggesting intracranial abnormality include high fever and change in mental status with and without focal signs.


Headache Child PCAs

Headache Child PCAs. Neurologic signs and symptoms such as nuchal rigidity or alteration in consciousness may be indications for imaging. Symptoms in infants may be nonspecific, including fever, poor feeding, irritability, and lethargy. Seizures are not uncommon in these young children, mostly occurring when the inflammation has progressed to involve the brain parenchyma. Older children may have fever, headache, nausea, vomiting, confusion, stiff neck, and photophobia. Symptoms of viral meningitis can resemble those of the flu. An MRI scan of the brain is indicated in patients with signs of intracranial infection with headache. MRI with and without IV contrast is indicated in the evaluation of intracranial infections that include meningitis, encephalitis, and brain abscess. MRI may improve the sensitivity for detecting encephalitis as T2 FLAIR is sensitive for vasogenic edema, diffusion-weighted imaging is sensitive for cytotoxic edema, and postcontrast T1 and T2 FLAIR sequences are sensitive for meningeal enhancement. The combination of MRI sequences can be very helpful to exclude mimics of encephalitis, identify the extent of inflammation, and confirm if lesion distribution is concordant with symptoms [52]. The distribution of abnormalities on MRI can help guide in determining the pathogen in some cases. For instance, brainstem and spinal cord involvement is common with enterovirus, and basal ganglia/thalamic involvement is common with West Nile virus or Japanese encephalitis. It is important to note that the classic limbic distribution of herpes simplex virus-1 may not always be present, and that extratemporal involvement is not uncommon [52]. Extracranial infections, including subdural empyemas (SDE) and epidural empyemas, can also be well evaluated with MRI. Epidural empyemas are collections of suppurative fluid located between the skull and dura.


Headache Child PCAs

Headache Child PCAs. In infants, SDE is most commonly a complication of purulent meningitis, whereas in older children the source of SDE is typically direct extension of sinusitis or otitis media into the extracranial spaces. MRI can help identify epidural empyemas because of its ability to distinguish between different types of fluid, especially with use of diffusion- weighted imaging. Acute meningitis is a common neurological emergency and the diagnosis is usually made based on clinical and laboratory findings. CT Neuroimaging is reserved for specific adverse features, such as prompt diagnosis of SAH, or underlying causes, such as mastoiditis. Neurologic signs and symptoms such as nuchal rigidity or alteration in consciousness may be indications for imaging with CT. However, the sensitivity of CT in diagnosing pediatric encephalitis in comparison to MRI is generally poor [52]. In the emergency setting, CT may be indicated in evaluating children with suspected intracranial infection, often performed prior to lumbar puncture. IV contrast is recommended in these patients if MRI is not rapidly available. A negative noncontrast CT scan of the head should not conclude the evaluation for suspected encephalitis. In a study by Bykowski et al [52], cranial CTs were the initial study in 94 patients, and abnormal findings were present in 22. An additional 26 children had a normal acute CT and abnormal findings identified on MRI performed within 2 days [52]. CTA The role for CTA is limited in children with headache attributed to infection unless SAH or stroke is suspected and MRI/MRA is not possible. CTV As children with mastoiditis are at particularly high risk for venous sinus thrombosis, CTV may be helpful in the evaluation of these patients. Children with sphenoid sinusitis are also at risk for cavernous sinus thrombosis, and CTV may be helpful in these patients. MRA The role for MRA is limited in children with headache attributed to infection unless SAH or stroke is suspected.


Headache Child PCAs

Headache Child PCAs. If arteritis is suspected, as can be seen in the setting of sphenoid sinusitis and skull base osteomyelitis, MRA may be helpful. MRV If venous sinus thrombosis is suspected, MRV is indicated. It should be noted, however, that in some cases of infection-induced venous sinus or cavernous sinus thrombosis, contrast-enhanced MRI could be superior to MRV as it shows the cross-sectional area of the vein with direct delineation of the thrombus itself and not just the absence of flow in the lumen, as seen on MRV [53]. The use of contrast in MRV depends on institutional preferences. Arteriography There is usually no role for arteriography in the evaluation of children with headache related to infection. MRI Patients who have a history of subacute or remote trauma may present with headaches. Post-traumatic headache is defined as a headache that begins within 2 weeks of a closed head injury. A prospective study of children admitted with a closed head injury (minor 79%, major 21%) found that 7% of children reported chronic post- traumatic headaches, 4% had episodic tension-type headaches, and 2.5% had migraine without aura [54]. When neurologic signs or symptoms are positive, when headaches are associated with vomiting, or when headaches are increasing in frequency, duration, or severity, regardless of the severity of the initial trauma, neuroimaging, preferably with noncontrast MRI, is indicated. SWI or GRE imaging is helpful in identifying hemosiderin deposition related to prior hemorrhage and should be included in the MRI examination. These sequences are limited because of susceptibility artifact in children with orthodontic braces or other metallic hardware, especially on higher Tesla strength MRI scanners. CT CT is usually not indicated in children with headaches attributed to remote trauma. A retrospective study by Dayan et al [55] identified 2,462 children who had minor blunt head trauma and headaches as their only symptom.


Female Infertility

Female Infertility.  Introduction/Background Overall, infertility affects about 15.5% of women [1]. Infertility investigations are generally initiated after 12 months of unprotected intercourse without resultant pregnancy in women <35 years of age, whereas they are initiated after 6 months of unprotected intercourse without pregnancy in women >35 years of age. An investigation may commence sooner in couples with a known condition or medical history predisposing to infertility. The most common known causes of infertility are male factor (26%), ovulatory failure (21%), and tubal damage (14%), although in 28% of couples infertility remains unexplained [2]. Female-specific causes of infertility include deterioration of oocyte quality with increasing maternal age; ovulatory disorders, most notably polycystic ovarian syndrome (PCOS); history of salpingitis, such as that caused by chlamydia infection; endometriosis; and uterine cavity abnormalities interfering with implantation causing inability to become pregnant or causing recurrent pregnancy loss [3]. These potential causes of female infertility will be discussed here. Imaging can be used to count ovarian follicles and help determine ovarian reserve, particularly in advanced maternal age. Imaging can also be useful in diagnosing polycystic ovarian morphology (PCOM) in women suspected of having PCOS. PCOS is the leading cause of anovulatory infertility, affecting at least 7% of adult women [4]. Women with PCOS experience hyperandrogenism, infertility, and have PCOM defined as >25 small follicles in at least one ovary or a single ovarian volume >10 mL on transvaginal ultrasound (TVUS) [5]. Because PCOM may be present in up to one-third of reproductive-aged women [6], the imaging findings of PCOM are not sufficient for the diagnosis of PCOS but serve to support the diagnosis of PCOS in women with the clinical features. Endometriosis affects at least one-third of women with infertility and up to 10% of reproductive-aged women [7].


Female Infertility

Female Infertility. Although endometriosis is associated with infertility, the mechanism is unclear [8]. Imaging is useful in characterizing some features of endometriosis; however, small endometrial implants are not well detected on imaging. Therefore, laparoscopy remains the standard for both diagnosis and staging of endometriosis [9,10]. Women with a history of pelvic infection or surgery may develop intrauterine synechiae, fallopian tube abnormalities that include occlusion, and peritubular adhesions [11], potentially causing infertility. Imaging evaluation in these women focuses primarily on the fallopian tubes. Reprint requests to: publications@acr.org Female Infertility adhesions cause the loss of pregnancy [17]. Although hysteroscopy is the reference standard for visualizing intrauterine adhesions [18], imaging examinations can aid in making this diagnosis with a less invasive approach. Uterine fibroids are suspected to be related to recurrent pregnancy loss; however, there is insufficient evidence to confirm a causal relationship. Uterine adenomyosis, although previously felt to be more common in multiparous women, has now been associated with increased rates of spontaneous abortion and implantation failure [19]. In approximately 18% of women, a uterine abnormality such as fibroids or MDA is identified as a causative factor for recurrent pregnancy loss [20]. Special Imaging Considerations MR hysterosalpingography (HSG) is an additional technique that can demonstrate tubal patency and may be useful in women in whom both MRI and HSG need to be performed [23]; however, it remains an investigational tool [24]. US Pelvis Transabdominal Although transabdominal US and TVUS may be performed together for evaluation of the ovaries, transabdominal US should be relied upon only if the ovaries are not adequately evaluated via a transvaginal approach. US Pelvis Transvaginal TVUS can be used to monitor follicle development [27], perform antral follicle counts [28], and measure ovarian volume.


Female Infertility

Female Infertility. When the ovarian volume is <3 cm3 and <5 antral follicles are present, this suggests diminished ovarian reserve [29]. MRI Pelvis A recent study in obese adolescents with suspected PCOS demonstrated that MRI without IV contrast can provide reproducible and reliable ovarian volume assessment; however, ovarian follicle counts had only moderate interobserver agreement. Nonetheless, in the obese adolescent or patient in whom TVUS is unacceptable and transabdominal US limited, MRI may provide additional information on PCOM [25,26,30]. US Pelvis Color Doppler Although increased central stromal vascularity has been demonstrated in the ovaries of women with PCOS, there is limited evidence to indicate color Doppler should be performed routinely in the evaluation of PCOM [31]. Female Infertility US Pelvis Transabdominal Transabdominal US is often performed in conjunction with TVUS; however, in some settings it may be performed in isolation. The transabdominal approach is generally not suitable to record an accurate follicle count but is considered reliable to determine if the ovarian volume is >10 mL. On occasion, with a high superficial location, the ovary may be better seen for follicle counts than via the TVUS route but remains less reliable because of lower transducer frequency. Variant 3: Female infertility. History or clinical suspicion of endometriosis. Initial imaging. Fluoroscopy Hysterosalpingography HSG to assess tubal patency and the uterine cavity has been proposed as part of an infertility workup in women with endometriosis [8]. However, in one study, 21% of women undergoing infertility evaluation were found to have endometriosis at surgery despite a normal HSG [33]. Although HSG may be helpful in diagnosing tubal occlusion or patency in patients with endometriosis, other imaging modalities are more sensitive in detecting endometriosis.


Female Infertility

Female Infertility. MRI Pelvis MRI has been shown to have a sensitivity of 82% to 90% and specificity of 91% to 98% for the diagnosis of endometriomas and can be used when the findings on TVUS are indeterminate [34-36] or when assessment for deep infiltrating endometriosis is required prior to fertility-sparing surgery. Although IV contrast is useful for the assessment of PID and for determining if ovarian masses have enhancing components, IV contrast is not routinely used for the assessment of endometriosis [34]. The typical MRI features of an endometrioma are high signal on T1- weighted with low signal on T2-weighted images (T2 shading) from intracellular methemoglobin, crosslinking of proteins, and iron. Additionally, the T2 dark spot sign has 93% specificity in differentiating endometriomas from hemorrhagic cysts, whereas T2 shading is sensitive but not specific for endometriomas [37]. Deep infiltrating endometriosis presents as low signal intensity regions with or without hyperintense foci on T2- and/or T1-weighted images. Despite administration of gadolinium, studies do not attempt to demonstrate a difference in detection of deep infiltrating endometriosis with gadolinium as compared to without [38,39]. Adhesions are frequently present in endometriosis and can be suspected, in the presence of a uterus, fixed in retroversion, low-signal intensity bands, obliteration of organ interfaces, and/or obliteration of the cul-de-sac [40]. In a study of 159 women who underwent surgery for clinical suspicion of deep infiltrating endometriosis, MRI was 92.4% sensitive and 94.6% specific in detecting intestinal endometriosis, 88% sensitive and 83.3% specific in detecting deep infiltrating endometriosis in posterior locations (uterosacral ligament, retrocervical, rectovaginal septum, vaginal fornix), and 50% sensitive and 97.3% specific in detecting bladder wall endometriosis [38].


Female Infertility

Female Infertility. Adherence to or angulation of bowel loops toward the posterior surface of the uterus has been shown to be 83.7% sensitive to diagnose cul-de-sac obliteration, whereas displacement of pelvic free fluid was 95% sensitive and presence of a retrouterine fibrous mass was 97.1% sensitive [40]. These findings may have been enhanced in this study because of the administration of vaginal and rectal sterile US gel as well as an IV antispasmodic. Another study similarly identified serosal uterine fibrotic plaques as having the best accuracy for posterior cul-de-sac obliteration [41] but did not assess displacement of free pelvic fluid. Overall, MRI has value in assessing for endometriomas and other signs of endometriosis, such as angulation of bowel loops toward the posterior surface of the uterus, displacement of pelvic free fluid, and detection of retro-uterine fibrous masses. US Pelvis Color Doppler Endometrial implants have limited vascularity. The presence of Doppler blood flow in a suspected endometrial implant should prompt investigation for neoplasm [42]. Doppler can also be useful in differentiating endometriomas and endometrial implants, which are typically avascular, from other ovarian masses and normal structures [43]. Female Infertility US Pelvis Transrectal Transrectal US can also be useful in the detection of deep infiltrating endometriosis. Compared with surgery, transrectal US was shown to be 97% sensitive and 96% specific for the detection of rectovaginal endometriosis and was 80% sensitive and 97% specific in diagnosing uterosacral ligament implants [44]. In another study, 317 patients underwent pelvic MRI, TVUS, and transrectal US prior to laparoscopy. This study showed transrectal US had the highest sensitivity at 82.8%, but MRI was the most specific at 93.9% for evaluation of the uterosacral ligament, and the three techniques were similar for assessing the rectovaginal septum, bladder, and distal ureters.


Female Infertility

Female Infertility. MRI was superior to TVUS and transrectal US in diagnosing retrocervical endometriosis [45]. Transrectal US is limited to a small anatomic area [43] but can be useful in some patients, especially those unable to undergo TVUS [45]. US Pelvis Transvaginal TVUS, especially when combined with real-time physical examination, can be useful in the detection of both ovarian and nonovarian endometriosis. Some studies have demonstrated superiority of TVUS over MRI in the detection of rectosigmoid and retrocervical endometriosis [46-49]. TVUS can demonstrate macroscopic endometriomas that are often bilateral. On US, an endometrioma typically appears as an adnexal or ovarian mass with homogenous low-level internal echoes. The presence of echogenic foci in the wall (hemosiderin deposits) or multilocularity further increases the likelihood that a mass with this appearance is an endometrioma [50]. Nonovarian endometriosis can be assessed best with dynamic US by looking for the uterine sliding sign, assessing for nodules at sites of tenderness, assessing ovarian mobility, and looking for hypoechoic nodules outside of the ovaries [51]. US Sonohysterography To our knowledge, there is no relevant literature to support performing isolated US sonohysterography in patients with a history or clinical suspicion of endometriosis. Contrast sonohysterography or saline-infusion sonohysterography (SIS) provides an assessment of the uterine cavity. Although the endometrium can be assessed by TVUS, SIS is particularly useful in assessing potential causes of infertility, including intrauterine adhesions, endometrial polyps, and leiomyomas [52]. Antibiotic administration or prophylactic use of antibiotics is at the discretion of the referring physician if there is a prior history of PID or if hydrosalpinx is noted at the time of the study.


Female Infertility

Female Infertility. US Sonohysterography with Tubal Contrast Agent Hysterosalpingo-contrast sonography (HyCoSy) involves instilling echogenic contrast, typically an agitated air and saline mixture, into the uterus with real-time US to observe the material distending the uterine cavity, filling the fallopian tubes, and spilling out over the adjacent ovary [53]. Accuracy of HyCoSy is similar to HSG when compared with laparoscopy with chromopertubation in determining tubal patency with sensitivity of 75% to 96% and specificity of 67% to 100% when compared directly with laparoscopy with chromopertubation [54]. It has been proposed that TVUS with 3-D imaging of the uterus and ovaries followed by SIS and HyCoSy with agitated saline can be performed in one session as a comprehensive infertility examination [42]. In women with endometriosis, HyCoSy has been shown to be 91% accurate compared with laparoscopy in diagnosing tubal patency [55]. This modality can also detect endometriomas as well as pelvic adhesive disease and endometriotic nodules, especially in the hands of well-trained operators. Variant 4: Female infertility. Suspicion of tubal occlusion. Initial imaging. Fluoroscopy Hysterosalpingography HSG allows detection of tubal patency, tubal size, tubal irregularity, and peritubal disease. It can also detect intrauterine synechiae, which typically present as irregular endometrial filling defects [11]. Tubal flushing during HSG has also been shown to increase pregnancy rates up to 38% compared with pregnancy rates of up to 21% in women being investigated for infertility who did not undergo HSG. Pregnancy rate in this study was highest in women who underwent HSG with oil-soluble contrast [56]. However, unlike performance of HSG with water- soluble contrast agents, the use of oil-based contrast material for HSG carries the increased risk of oil emboli if there is myometrial intravasation [57].


Female Infertility

Female Infertility. Although HSG has been historically regarded as the imaging study of choice in assessing tubal patency, it is only 65% sensitive and 85% specific for diagnosing tubal patency when compared Female Infertility with laparoscopy with chromopertubation [58], which is widely accepted as the reference standard for evaluating tubal patency. MRI Pelvis MRI is useful in the detection of hydrosalpinges, most commonly due to prior PID, and is superior to TVUS in the assessment of PID, although this refers to acute PID, which is outside of the scope of this topic (95% sensitive and 89% specific compared to 81% sensitive and 78% specific) [59]. Hydrosalpinges are detected in subclinical or chronic PID secondary to scarring of the fallopian tubes or tubal obstruction by peritoneal bands from previous inflammation [60]. In a blinded study of 41 patients with hydrosalpinx at surgery, hydrosalpinx was accurately diagnosed in 31 patients (75.6%) on MRI [61]. Although IV contrast is useful in assessing additional complications of PID, it is not necessary for the evaluation of hydrosalpinges [34,60]. US Pelvis Transvaginal Hydrosalpinx may occur in the setting of distal tubal occlusion, most commonly due to prior PID [62]. The finding of hydrosalpinx has implications for patients who may undergo in vitro fertilization [63]. TVUS has been shown to be 86% sensitive in detecting hydrosalpinx [64]. Apart from detection of hydrosalpinges, TVUS has not been shown to be effective in documenting tubal patency. US Sonohysterography To our knowledge, there is no relevant literature to support performing isolated US sonohysterography in patients with suspicion of tubal occlusion; however, the presence of increased fluid in the posterior cul-de-sac following sonohysterography may indicate tubal patency.


Female Infertility

Female Infertility. US Sonohysterography with Tubal Contrast Agent HyCoSy involves instilling echogenic contrast, typically an agitated air and saline mixture, into the uterus with real- time US to observe the material distending the uterine cavity, filling the fallopian tubes, and spilling out over the adjacent ovary [53]. HyCoSy is similar to HSG when compared with laparoscopy with chromopertubation in determining tubal patency [54]. It has been proposed that TVUS with 3-D imaging of the uterus and ovaries followed by SIS and HyCoSy with agitated saline can be performed in one session as a comprehensive infertility examination [42]. HyCoSy has been shown to be 91% accurate compared with laparoscopy in diagnosing tubal patency in women with endometriosis [55]. Hysterosalpingo-foam sonography in combination with 2-D or 3-D imaging has demonstrated improved accuracy of 93.7% and better concordance with laparoscopy compared with 2-D or 3-D air or saline HyCoSy [65,66] for assessment of tubal patency. The addition of high-definition flow (bidirectional Doppler feature) achieved even higher accuracy at 96.9%, comparable with the reference method of laparoscopic chromopertubation with dye [65]. However, high-definition flow still needs to be validated by other groups. Variant 5: Female infertility. Recurrent pregnancy loss. Initial imaging. Fluoroscopy Hysterosalpingography In 24 cases of surgically proven MDA, MRI was 100% accurate, 2-D TVUS was 92% accurate, and hysterosalpingogram was only 16.7% accurate in characterizing MDAs [67]. Although HSG can visualize the uterine cavity, it cannot always provide complete information about the external uterine contour, preventing accurate distinction between a septate and a bicornuate uterus. A study of 54 women with suspected Asherman syndrome discovered 3-D US was 100% sensitive, and HSG was 66.7% sensitive in grading intrauterine adhesions compared with hysteroscopy [68].