Thoracic Back Pain

Thoracic Back Pain.  Introduction/Background In the United States, spinal pain is one of the leading causes of disability, health care costs, and emergency room visits [1,2]. The lumbar and cervical spine regions have been extensively studied and have well-established associations with pain and disability. Comparatively, thoracic back pain (TBP) has received less attention in terms of genetic and epidemiological research [3]. However, the thoracic spine is a common site for inflammatory, neoplastic, metabolic, infectious, and degenerative conditions [3]. Therefore, TBP may be equally disabling and associated with significant morbidity. Uncomplicated acute TBP and/or radiculopathy may be a benign, self-limited condition that does not warrant any imaging studies [5-8]. Imaging may be considered in those patients who have had up to 6 weeks of medical management and physical therapy that resulted in little or no improvement in their back pain. Imaging may also be considered for those patients presenting with red flags, raising suspicion for a serious underlying condition, such as symptomatic spinal canal stenosis, cord deformity or compression, malignancy, fracture, or infection [9,10]. For those patients with significant trauma, myelopathy, or prior thoracic spine fusion, early imaging may also be warranted [11-14]. Because the thoracic spine is a common site for osteoporotic compression fractures [15-17], early imaging should also be considered in patients with known osteoporosis or risk factors such as >65 years of age or chronic steroid use [18]. For those patients without neurologic compromise and who present with minor risk factors for cancer, inflammatory back disease (eg, ankylosing spondylitis), vertebral compression fracture, or symptomatic spinal stenosis, imaging may be considered after a trial of therapy. Initial Imaging Definition Initial imaging is defined as imaging at the beginning of the care episode for the medical condition defined by the variant.


Thoracic Back Pain

Thoracic Back Pain. More than one procedure can be considered usually appropriate in the initial imaging evaluation when: 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 OR Discussion of Procedures by Variant Variant 1: Adult. Acute Thoracic back pain without myelopathy or radiculopathy. No red flags. No prior management. Initial imaging. There is a lack of evidence supporting or refuting imaging early or before conservative treatment for TBP [3,20]. However, extrapolating from the low back pain (LBP) evidence, imaging is typically not warranted in this setting. Acute (<4 weeks duration), uncomplicated (no red flags) LBP with or without radiculopathy, is considered a self- limiting condition that is responsive to medical management and physical therapy in most patients [5-8]. Numerous studies have shown routine imaging provides no clinical benefit in this LBP group [6]. Thoracic disc disease is less common than in the cervical or lumbar spine [21]. This may be due to the fact that the thoracic spine is the only portion of the spine with additional structures (ie, ribs) to help in weight-bearing. There is also relatively limited mobility in the thoracic spine as the costovertebral joint limits flexion, the rib cage limits rotation and lateral bending, and the discs are relatively small in size compared to the cervical or lumbar spine. Symptomatic thoracic disc disease occurs most frequently below the level of T7. Thoracic disc abnormalities such as herniations, bulges, annular fissures, and cord contour deformity are common in asymptomatic patients [22].


Thoracic Back Pain

Thoracic Back Pain. Thoracic disc imaging abnormalities can therefore be seen in a substantial number of people without mid back pain. With regards to thoracic facet joints, as in the lumbar spine, morphologic imaging changes of osteoarthritis do not correlate with pain [23]. Bone Scan Whole Body There is no relevant literature to support the use of bone scans whole body in the initial evaluation of acute uncomplicated TBP. Bone Scan with SPECT or SPECT/CT Thoracic Spine There is no relevant literature to support the use of bone scans with single-photon emission CT (SPECT) or SPECT/CT thoracic spine in the initial evaluation of acute uncomplicated TBP. CT Myelography Thoracic Spine There is no relevant literature to support the use of CT myelography thoracic spine in the initial evaluation of acute uncomplicated TBP. No radiologic distinction has been noted between asymptomatic and symptomatic discs on postmyelographic CT [24]. CT Thoracic Spine With IV Contrast There is no relevant literature to support the use of CT thoracic spine with intravenous (IV) contrast in the initial evaluation of acute uncomplicated TBP. CT Thoracic Spine Without and With IV Contrast There is no relevant literature to support the use of CT thoracic spine without and with IV contrast in the initial evaluation of acute uncomplicated TBP. CT Thoracic Spine Without IV Contrast There is no relevant literature to support the use of CT thoracic spine without IV contrast in the initial evaluation of acute uncomplicated TBP. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG)-PET/CT skull base to mid-thigh in the initial evaluation of acute uncomplicated TBP. MRI Thoracic Spine With IV Contrast There is no relevant literature to support the use of MRI thoracic spine with IV contrast in the initial evaluation of acute uncomplicated TBP. Thoracic Back Pain


Thoracic Back Pain

Thoracic Back Pain. MRI Thoracic Spine Without and With IV Contrast There is no relevant literature to support the use of MRI thoracic spine without and with IV contrast in the initial evaluation of acute uncomplicated TBP. MRI Thoracic Spine Without IV Contrast There is no relevant literature to support the use of MRI thoracic spine without IV contrast in the initial evaluation of acute uncomplicated TBP. Radiography Thoracic Spine There is no relevant literature to support the use of radiography in the initial evaluation of acute uncomplicated TBP. Variant 2: Adult. Subacute or chronic thoracic back pain without myelopathy or radiculopathy. No red flags. Failed conservative management. Initial imaging. As with acute TBP, few studies support or refute imaging for patients with subacute or chronic midback pain without neurologic symptoms. However, as with LBP, imaging is typically not considered useful in this setting [6,7]. For patients with subacute (4-12 weeks duration) or chronic (>12 weeks duration) TBP without red flags or prior management, conservative therapy should still be considered first-line [25]. Bone Scan Whole Body There is no relevant literature to support the use of bone scans whole body in the initial evaluation of subacute or chronic TBP without red flags or neurologic deficits. Bone Scan with SPECT or SPECT/CT Thoracic Spine There is no relevant literature to support the use of bone scans with SPECT or SPECT/CT thoracic spine in the initial evaluation of subacute or chronic TBP without red flags or neurologic deficits. CT Myelography Thoracic Spine There is no relevant literature to support the use of CT myelography thoracic spine in the initial evaluation of subacute or chronic TBP without red flags or neurologic deficits. CT Thoracic Spine With IV Contrast There is no relevant literature to support the use of CT thoracic spine with IV contrast in the initial evaluation of subacute or chronic TBP without red flags or neurologic deficits.


Thoracic Back Pain

Thoracic Back Pain. CT Thoracic Spine Without and With IV Contrast There is no relevant literature to support the use of CT thoracic spine without and with IV contrast in the initial evaluation of subacute or chronic TBP without red flags or neurologic deficits. CT Thoracic Spine Without IV Contrast There is no relevant literature to support the use of CT thoracic spine without IV contrast in the initial evaluation of subacute or chronic TBP without red flags or neurologic deficits. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of FDG-PET/CT skull base to mid-thigh in the initial evaluation of subacute or chronic TBP without red flags or neurologic deficits. MRI Thoracic Spine With IV Contrast There is no relevant literature to support the use of MRI thoracic spine with IV contrast in the initial evaluation of subacute or chronic TBP without red flags or neurologic deficits. MRI Thoracic Spine Without and With IV Contrast There is no relevant literature to support the use of MRI thoracic spine without and with IV contrast in the initial evaluation of subacute or chronic TBP without red flags or neurologic deficits. MRI Thoracic Spine Without IV Contrast There is no relevant literature to support the use of MRI thoracic spine without IV contrast in the initial evaluation of subacute or chronic TBP without red flags or neurologic deficits. Radiography Thoracic Spine There is no relevant literature to support the use of radiography in the initial evaluation of subacute or chronic TBP without red flags or neurologic deficits. Thoracic Back Pain Variant 3: Adult. Thoracic back pain with myelopathy or radiculopathy. Initial imaging. The goal of imaging is to identify potential actionable pain generators that could be targeted for medical treatment, intervention, or surgery. MRI of the thoracic spine has become the initial imaging modality of choice in these patients [13,26,27].


Thoracic Back Pain

Thoracic Back Pain. Thoracic myelopathy is most commonly due to compressive etiologies, including structural causes resulting in spinal canal stenosis, cord compression/deformity, or other inflammatory, infectious, vascular, or neoplastic etiologies [28]. Spinal stenosis is a common cause of myelopathy, typically from disc herniations (including giant calcified disc herniations), usually below T7, facet arthropathy, or ligamentum flavum ossification [29]. Symptomatic thoracic disc herniations are more common in patients in their third to fifth decades of life and, in more than one-third of patients, are associated with a history of trauma. On imaging, these are often calcified (20%- 65%) and sometimes intradural (5%-10%) [30]. Patients with symptomatic thoracic disc herniations may have thoracic midback pain (76%), motor/sensory deficit (61%), spasticity/hyperreflexia (58%), positive Babinski sign (55%), or bladder dysfunction (24%). Symptomatic thoracic disc herniations requiring surgery are rare, accounting for 1% to 2% of all discectomies [31]. Indication for surgery is usually severe, intractable pain, or progressive/severe myelopathy. Thoracic radiculopathy is most commonly due to mechanical nerve root compression from degenerative, metabolic, infectious, or neoplastic causes. Bone Scan Whole Body There is no relevant literature to support the use of whole-body bone scans in the initial imaging of TBP and myelopathy or radiculopathy. Bone Scan with SPECT or SPECT/CT Thoracic Spine There is no relevant literature to support the use of bone scan with SPECT or SPECT/CT in the initial imaging of TBP and myelopathy or radiculopathy. CT Myelography Thoracic Spine CT myelography of the thoracic spine can be useful in assessing the patency of the spinal canal/thecal sac.


Thoracic Back Pain

Thoracic Back Pain. CT myelography may also be complementary to MRI for identifying and differentiating between certain causes of myelopathy, such as ventral cord herniation versus dorsal thoracic arachnoid web or cyst, and also for presurgical or preradiation treatment planning due to its high detail and exquisite resolution of the contents of the spinal canal [32]. CT myelography has the disadvantage of requiring lumbar puncture for intrathecal injection of myelographic contrast. CT Thoracic Spine With IV Contrast There is no relevant literature to support the use of CT thoracic spine with IV contrast in the initial imaging of TBP and myelopathy or radiculopathy. CT Thoracic Spine Without and With IV Contrast There is no relevant literature to support the use of CT thoracic spine without and with IV contrast in the initial imaging of TBP and myelopathy or radiculopathy. CT Thoracic Spine Without IV Contrast There is no relevant literature to support the use of CT thoracic spine without IV contrast in the initial imaging of TBP and myelopathy or radiculopathy. However, CT thoracic spine without IV contrast may be useful for preoperative planning. CT delineates osseous structures and anatomy with high resolution and can aid in trajectory planning for hardware fixation. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of FDG-PET/CT skull base to mid-thigh in the initial imaging of TBP and myelopathy or radiculopathy. MRI Thoracic Spine With IV Contrast MRI thoracic spine with IV contrast is not typically performed independently as an initial study, because its interpretation is most informative when correlated with standard noncontrast sequences included in MRI thoracic spine with and without IV contrast. Thoracic Back Pain


Thoracic Back Pain

Thoracic Back Pain. MRI Thoracic Spine Without and With IV Contrast MRI thoracic spine without and with IV contrast may be the preferred initial study of choice in patients with TBP and myelopathy/radiculopathy when underlying malignancy, infection, or inflammation is clinically suspected. MRI Thoracic Spine Without IV Contrast MRI thoracic spine without IV contrast may be useful as an initial study of choice in patients with TBP and myelopathy/radiculopathy when structural/mechanical causes of compressive myelopathy or radiculopathy are clinically suspected. MRI thoracic spine without IV contrast is most useful in evaluating compressive myelopathy or radiculopathy because of its ability to accurately depict soft tissue pathology, assess vertebral marrow, and assess the spinal canal patency [20]. Heavily T2-weighted sequences such as CISS/FIESTA may be helpful to assess for structural etiologies such as dorsal thoracic arachnoid webs or for reducing metallic artifacts in patients with thoracic spinal hardware [33]. Radiography Thoracic Spine There is no relevant literature to support the use of thoracic spine radiography in the initial evaluation of patients with TBP and myelopathy. Radiography alone is not usually sufficient for diagnosing the specific pain generator in these patients or for guiding surgical or interventional options without MRI and/or CT imaging. However, it can provide complementary information that can be helpful in treatment planning, including for presurgical planning and postoperative assessment [11]. Variant 4: Adult. Thoracic back pain without or with myelopathy or radiculopathy. One or more of the following: low-velocity trauma, osteoporosis, elderly individual, or chronic steroid use. Initial imaging. Elderly (>65 years of age) individuals, those with known osteoporosis, prior benign nontraumatic compression fracture, or chronic steroid use are at risk for additional compression fractures even with minimal to no trauma [34,35].


Thoracic Back Pain

Thoracic Back Pain. Patients with low-velocity trauma, and without risk factors for osteoporosis, may not need dedicated thoracic spine imaging if asymptomatic. Bone Scan Whole Body Whole-body bone scans may be helpful in the setting of compression fracture(s) to help identify fracture acuity and to appropriately select patients for intervention [36], particularly if MRI cannot be safely/easily obtained. Bone Scan with SPECT or SPECT/CT Thoracic Spine Bone scan with SPECT or SPECT/CT may be helpful in the setting of compression fracture(s) to help identify fracture acuity and to appropriately select patients for intervention [36]. CT Myelography Thoracic Spine There is no relevant literature to support the use of CT myelography thoracic spine in the initial imaging assessment of this group. CT Thoracic Spine With IV Contrast There is no relevant literature to support the use of CT thoracic spine with IV contrast in the initial imaging assessment of this group. CT Thoracic Spine Without and With IV Contrast There is no relevant literature to support the use of CT thoracic spine without and with IV contrast in the initial imaging assessment of this group. CT Thoracic Spine Without IV Contrast CT thoracic spine without IV contrast may be useful as an initial study in the emergency room setting or for presurgical planning, particularly if radiographs are negative [36]. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of FDG-PET/CT skull base to mid-thigh in the initial imaging assessment of this group. MRI Thoracic Spine With IV Contrast MRI thoracic spine with IV contrast is not typically performed independently as an initial study, because its interpretation is most informative when correlated with standard noncontrast sequences included in MRI thoracic spine with and without IV contrast. Thoracic Back Pain


Thoracic Back Pain

Thoracic Back Pain. MRI Thoracic Spine Without and With IV Contrast MRI thoracic spine without and with IV contrast is not typically performed as an initial study in this group unless there is concern for underlying neoplasm, infection, or inflammation. MRI Thoracic Spine Without IV Contrast MRI thoracic spine without IV contrast may be useful as an initial study in this group due to its excellent soft tissue resolution, particularly if there is concern for soft tissue or neurologic compressive injury, to identify a compression fracture (even if radiographs are negative), or to plan intervention (identify marrow edema) [36]. Radiography Thoracic Spine Radiography may be useful as an initial screening study in TBP with risk factors for osteoporotic fractures in patients without neurologic deficits [35]. However, it should be noted that thoracic vertebral body fractures seen on radiographs may be difficult to estimate in terms of chronicity without priors to compare to. In those cases, MRI or bone scan may be needed to age the fracture acuity. Bone Scan Whole Body There is no relevant literature to support the use of whole-body bone scan in the initial imaging assessment of this group. Bone Scan with SPECT or SPECT/CT Thoracic Spine There is no relevant literature to support the use of bone scans with SPECT or SPECT/CT in the initial imaging assessment of this group. CT Myelography Thoracic Spine CT myelography of the thoracic spine may be helpful in patients or for treatment planning (surgery, radiation). CT Thoracic Spine With IV Contrast There is no relevant literature to support the use of CT thoracic spine with IV contrast in the initial imaging assessment of this group. CT Thoracic Spine Without and With IV Contrast There is no relevant literature to support the use of CT thoracic spine without and with IV contrast in the initial imaging assessment of this group.


Thoracic Back Pain

Thoracic Back Pain. CT Thoracic Spine Without IV Contrast CT thoracic spine without IV contrast may be helpful for presurgical planning or to delineate the osseous anatomy, particularly if there is osseous destruction [37]. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of FDG-PET/CT skull base to mid-thigh in the initial imaging assessment of this group. MRI Thoracic Spine With IV Contrast MRI thoracic spine with IV contrast is not typically performed independently as an initial study, because its interpretation is most informative when correlated with standard noncontrast sequences included in MRI thoracic spine with and without IV contrast. MRI Thoracic Spine Without and With IV Contrast MRI without and with IV contrast is the initial imaging modality of choice in patients with TBP and suspected neoplasm or infection [36,38-42]. Thoracic Back Pain MRI Thoracic Spine Without IV Contrast MRI without IV contrast may be useful in this setting to identify marrow replacing lesions, osseous destruction, canal compromise, and cord signal abnormality. However, the addition of postcontrast sequences would be more sensitive in identifying thoracic spinal infection and its complications, assessing small marrow replacing lesions, and identifying intradural disease [39-44]. Radiography Thoracic Spine Radiographs have low sensitivity but may be useful in the urgent/emergent setting to identify osseous destruction or change in alignment in patients with TBP and suspected infection or neoplasm [45]. Variant 6: Adult. Thoracic back pain without or with myelopathy or radiculopathy. Radiograph shows bone destruction or fracture or spinal deformity. Next imaging study. In patients with TBP and osseous destruction or spinal deformity the role of imaging is to delineate osseous detail and anatomy and assess the integrity of the soft tissue and neural structures, particularly that of the spinal canal.


Thoracic Back Pain

Thoracic Back Pain. Additionally, if spinal hardware is present, assessing hardware integrity and position is also a common indication for imaging. More than one imaging modality may be indicated for diagnosis and treatment planning. Bone Scan Whole Body There is no relevant literature to support the use of whole body bone scans in the initial imaging assessment of this group. Bone Scan with SPECT or SPECT/CT Thoracic Spine There is no relevant literature to support the use of bone scan with SPECT or SPECT/CT in the initial imaging assessment of this group. CT Myelography Thoracic Spine CT myelography may be useful in this setting in patients with spinal hardware. CT Thoracic Spine With IV Contrast There is no relevant literature to support the use of CT thoracic spine with IV contrast in the initial imaging assessment of this group. CT Thoracic Spine Without and With IV Contrast CT thoracic spine without and with IV contrast may be useful in this clinical scenario. CT Thoracic Spine Without IV Contrast In patients with TBP with or without myelopathy or radiculopathy when there is evidence of osseous destruction or spinal deformity on radiographs, both MRI and CT may be useful as an initial imaging modality [11,46]. CT can better depict the osseous detail, and MRI is more useful for assessing the integrity of the soft tissue and neural structures, particularly that of the spinal canal. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of FDG-PET/CT skull base to mid-thigh in the initial imaging assessment of this group. MRI Thoracic Spine With IV Contrast MRI thoracic spine with IV contrast is not typically performed independently as an initial study, because its interpretation is most informative when correlated with standard noncontrast sequences included in MRI thoracic spine with and without IV contrast.


Thoracic Back Pain

Thoracic Back Pain. MRI Thoracic Spine Without and With IV Contrast MRI thoracic spine without and with IV contrast may be useful as an imaging study in patients with TBP and evidence of spinal deformity or osseous destruction on radiography, particularly if there is concern for infection or neoplasm [44]. MRI Thoracic Spine Without IV Contrast MRI without IV contrast may be useful in this setting to identify marrow replacing lesions, osseous destruction, canal compromise, and cord signal abnormality [27]. However, the addition of postcontrast sequences would be more sensitive in identifying thoracic spinal infection and its complications, assessing small marrow replacing lesions, and identifying intradural disease. Thoracic Back Pain Variant 7: Adult. Thoracic back pain without or with myelopathy or radiculopathy. Post thoracic spine surgery. Follow-up imaging. In patients with TBP and a history of spinal fixation, imaging plays an important role in assessing hardware position and integrity, assessing spinal alignment, assessing fusion, identifying findings suspicious for infection, and assessing for postoperative complications, including, but not limited to, postoperative collections, scarring, adjacent segment degeneration, and spinal deformity [47]. Several imaging modalities may be useful and complementary in the initial assessment of patients with TBP and a history of instrumented spinal fixation [43,45,47]. Bone Scan Whole Body There is no relevant literature to support the use of whole-body bone scans in the initial imaging assessment of this group. Bone Scan with SPECT or SPECT/CT Thoracic Spine There is limited literature to support the use of bone scan with SPECT or SPECT/CT thoracic spine in the initial imaging assessment of this group. CT Myelography Thoracic Spine CT myelography may also be helpful in patients in whom a compressive etiology of their symptoms is clinically suspected.


Thoracic Back Pain

Thoracic Back Pain. CT Thoracic Spine With IV Contrast There is no relevant literature to support the use of CT thoracic spine with IV contrast in the initial imaging assessment of this group. CT Thoracic Spine Without and With IV Contrast There is no relevant literature to support the use of CT thoracic spine without and with IV contrast in the initial imaging assessment of this group. CT Thoracic Spine Without IV Contrast CT thoracic spine without IV contrast may be useful in assessing the integrity of fusion, identifying hardware position and integrity, and assessing alignment. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of FDG-PET/CT skull base to mid-thigh in the initial imaging assessment of this group. MRI Thoracic Spine With IV Contrast MRI thoracic spine with IV contrast is not typically performed independently as an initial study, because its interpretation is most informative when correlated with standard noncontrast sequences included in MRI thoracic spine with and without IV contrast. MRI Thoracic Spine Without and With IV Contrast MRI thoracic spine without and with IV contrast may be helpful in assessing for postoperative infection, hematoma, postoperative collections, or canal compromise. Many of these patients may benefit from scanning on mid field or 1.5T MRI scanners with metallic susceptibility artifact reduction protocols [46,47]. MRI Thoracic Spine Without IV Contrast MRI thoracic spine without IV contrast may help assess for postoperative hematoma or other collections, neurologic injury, residual foramina or canal stenosis, or cord compression. Radiography Thoracic Spine Radiographs may be useful for assessing the integrity of fusion, confirming hardware position and integrity, identifying adjacent level degeneration, and assessing alignment. Supporting Documents The evidence table, literature search, and appendix for this topic are available at https://acsearch. acr.org/list.


Staging of Pancreatic Ductal Adenocarcinoma.  Introduction/Background Prevalence, Etiology, Treatment, and Prognosis According to the American Cancer Society, the number of new pancreatic cancer cases estimated in the United States in 2017 is 53,670 [1]. The estimated number of deaths is 43,090 in 2017, with pancreatic adenocarcinoma remaining the fourth leading cause of cancer-related death in the United States. Difficulty in early detection and lack of effective screening methods invariably results in an advanced stage at presentation and poor prognosis. Associated risk factors include tobacco use (20% of patients), family history of pancreatic cancer (two or more first-degree relatives with pancreatic cancer reported in 10% of patients), chronic pancreatitis, diabetes, obesity, hereditary pancreatitis [2-4] and genetic alterations such as BRCA1, BRCA2, PALB2, p16 gene mutations, Lynch syndrome, and Peutz-Jeghers syndrome [5,6]. Screening is not currently recommended for the general population (US Preventive Services Task Force gives a D recommendation) [7]. However, some have suggested that screening patients at high risk of developing pancreatic cancer is feasible, while acknowledging that data for cost- effectiveness and benefit are still required [8]. To date, the most suitable imaging technology for such screening is unclear [5]. No specific tumor markers for pancreatic cancer exist, and although most patients will demonstrate elevation in serum cancer antigen 19-9, this has low specificity and is more often used to indicate disease progression. Pancreatic cancer develops insidiously in the exocrine cells, and as such, early disease is often asymptomatic or presents with vague symptoms such as loss of appetite, fatigue, and general malaise. Consequently, 80% to 85% of patients present with advanced disease without the option of surgical resection [9]. Overall survival for pancreatic cancer is 28% after 1 year and 7% after 5 years [1].


Staging of Pancreatic Ductal Adenocarcinoma. Localized pancreatic cancer, reportedly diagnosed in 9% of patients, is associated with a 26% 5-year survival. Distant stage disease at diagnosis is associated with only a 15% 1-year and 2% 5-year survival [1]. Given the poor prognosis, accurate staging is essential and pivotal to patient management decisions that are decided through a multidisciplinary approach [5]. Imaging plays a critical role in pancreatic cancer staging and therapeutic decision process. The imaging armamentarium used to evaluate pancreatic cancer includes multidetector computed tomography (MDCT), magnetic resonance imaging (MRI), endoscopic ultrasound (EUS), and fluorine-18-2-fluoro-2-deoxy- D-glucose positron emission tomography (FDG-PET)/CT. aPrincipal Author, University of Texas MD Anderson Cancer Center, Houston, Texas. bResearch author, University of Texas MD Anderson Cancer Center, Houston, Texas. cPanel Chair, Johns Hopkins University School of Medicine, Baltimore, Maryland. dMemorial Sloan Kettering Cancer Center, New York, New York; American College of Surgeons. eUniversity of Arizona, Banner University Medical Center, Tucson, Arizona. fMontefiore Medical Center, Bronx, New York. gColumbia University, New York, New York; American Gastroenterological Association. hUniversity of Florida College of Medicine, Gainesville, Florida. iNew York University Medical Center, New York, New York. jNorthwestern University, Chicago, Illinois. kUniversity of Texas MD Anderson Cancer Center, Houston, Texas. lUniversity of Alabama Medical Center, Birmingham, Alabama. mThe Warren Alpert School of Medicine at Brown University, Providence, Rhode Island. nUniversity of Illinois College of Medicine, Chicago, Illinois; American College of Physicians. oSpecialty Chair, University of Washington, Seattle, Washington. 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.


Staging of Pancreatic Ductal Adenocarcinoma. 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 Staging of Pancreatic Ductal Adenocarcinoma Key determinants of tumor stage can be summarized as follows: Stage IV disease is the presence of any distant metastases, stage III disease is any T4 disease, stage IIA disease is T3 disease with no distant metastases or nodal involvement, stage IIB disease is T1 through T3 disease with nodal involvement, stage IA is T1 disease without nodal involvement, and stage IB is T2 disease without nodal involvement. Treatment options include surgery, radiation therapy, and chemotherapy. Radical surgical resection offers potentially curative therapy, though it is seldom achieved. Furthermore, the general procedure-related morbidity rate is high at 20% and mortality rate is 1% to 4% [10,11]. Less than 20% of patients are candidates for surgery. For those undergoing surgery, the cancer is often too extensive for removal. Adjuvant chemotherapy with gemcitabine or chemoradiation after surgery has been reported by some to improve survival, but this is controversial due to conflicting published results [12-15]. Use of combination systemic therapy with gemcitabine and the targeted anticancer drug erlotinib, has been suggested to slightly increase survival in patients with advanced cancer [1]. Cure rates are highest for tumors that are truly localized to the pancreas (without extension beyond the pancreatic capsule or lymph node metastases). Surgical resection of small, localized tumors, (measuring <2 cm in maximum diameter), are associated with a survival rate of 18% to 24% [16]. Decisive factors determining tumor resectability include presence of distant metastases, and vascular involvement particularly the celiac axis, superior mesenteric artery (SMA), superior mesenteric vein (SMV), and portal vein (PV).


Staging of Pancreatic Ductal Adenocarcinoma. Motivation in efforts to increase surgical candidates is consequent to complete tumor resection being the sole option for cure. Close collaborative efforts between surgeons, oncologists, radiation oncologists, and diagnostic imaging has resulted in the development of resectable and borderline resectable disease criteria over the last decade. Increasingly sophisticated surgical techniques, including complex vascular reconstruction and use of neoadjuvant and adjuvant therapies have increased demand of more detailed and specific radiological interpretation of disease extent. Surgical definition of borderline resectable pancreatic cancer is based on five important observations: 1) long-term survival necessitates complete resection of the primary tumor and regional lymph nodes; 2) negative resection margins are less likely with increasing tumor involvement of the SMV-PV and SMA; 3) SMV-PV and hepatic artery resection (not SMA) at pancreatectomy has been associated with acceptable outcomes; 4) administration of conventional cytotoxic agents rarely results in down-staging locally advanced pancreatic cancer; and 5) tumor response to neoadjuvant chemotherapy and chemoradiation may be indicative of favorable tumor physiology and biology, and thus used to select patients who may benefit from aggressive surgery [17-25].


Staging of Pancreatic Ductal Adenocarcinoma. Overview of Imaging Modalities Radiologic evaluation of patients with pancreatic cancer for staging should assess tumor size, extension of tumor beyond the pancreas including adjacent significant vasculature (namely the SMA, celiac artery, common hepatic artery, and splenic artery, hepatic arterial variants, and the main PV, splenic vein, SMV, and whether the tumor is extending to divisions of these veins, which would preclude placement of a graft), presence of regional adenopathy (especially nodes that may be beyond the surgical field and may be suspicious, based on size or morphology), and whether there is metastatic involvement of the liver, peritoneum, and lungs. CT CT At many institutions, contrast-enhanced MDCT is the preferred imaging technique for the staging of pancreatic cancer. It is quick, robust, and especially has superb spatial resolution. It is particularly useful for the assessment of tumor involvement of vascular structures. Imaging should be obtained as a multiphasic acquisition, with a late arterial phase timed to optimize peak enhancement of the pancreas (typically at 45-50 seconds after the start of contrast injection, depending on injection rate) to maximize visualization of the primary tumor, and a portal venous phase for optimum enhancement of venous structures and to maximize detectability of typically hypodense liver metastases (typically 70 seconds after the start of contrast injection) [28]. Many practices employ use of bolus tracking to optimize timing of the arterial and portal venous phase of enhancement. A recent study comparing 64-detector row MDCT and 3T MRI showed overall comparable sensitivities and specificities between the two modalities regarding resectability (CT sensitivity 87%, specificity 63% to 75%; MRI sensitivity 93%, specificity 50% to 75%) [11].


Staging of Pancreatic Ductal Adenocarcinoma. A recent critical review of CT and MRI that was based on reports published between 1997 and 2009 also showed that CT and MRI performed comparably with both modalities showing improvement on more recent studies [29]. Notably, unenhanced CT has poor soft tissue contrast in comparison to MRI and therefore has marginal usefulness during staging. It should also be noted anecdotally, for the reasons given above, that in those institutions with MRI and CT capabilities, CT is typically the more used modality in the setting of staging pancreatic cancer. MRI Many MRI advances have been made in the past several years with regard to robustness of image quality, speed of image acquisition, and resolution in imaging. As noted above, MRI has been reported in a recent study to have a sensitivity of 93% and specificity of 50% to 75% for determination of resectability [11], and studies comparing state-of-the-art CT with state-of-the-art MRI report a similar overall performance [29]. MRI has inherently better soft tissue contrast than unenhanced CT enabling superior visualization of tumor without intravenous (IV) contrast administration. Although we could not identify studies specifically addressing noncontrast MRI staging sensitivity and specificity, MRI is preferable because techniques such as flow sensitive sequences and diffusion- weighted imaging provide valuable information when IV contrast is contraindicated. FDG-PET/CT There is considerable variation in how FDG-PET/CT is performed between institutions, with regard to the presence or absence of IV contrast, the presence or absence of oral contrast, as well as other parameters including slice thickness, and field-of-view. When performed without IV contrast, FDG-PET/CT has the same limitations as unenhanced CT with regard to local staging of the tumor. When performed with IV contrast, images are typically obtained at a single phase of contrast enhancement.


Staging of Pancreatic Ductal Adenocarcinoma. Studies that have recently examined the role of FDG-PET/CT in the staging of pancreatic cancer have focused on its supplementary ability to detect additional distant metastases beyond those detected by conventional cross-sectional imaging of the abdomen and pelvis or chest, abdomen, and pelvis given the advantage that FDG-PET/CT is a whole-body examination [31]. Nodal staging is a limitation for any of the imaging modalities because of its relative insensitivity to micrometastases detection. Another challenge is the varying imaging criteria for identifying potential nodal involvement between studies. A recent study that used, as criterion for nodal involvement, a nodal short axis diameter of >5 mm or morphologic features of necrosis showed an accuracy of 55% to 60% for the detection of nodal metastatic disease, which is similar to findings seen on older studies regardless of criteria (44%-68%) [29,32,34,35]. Little information is available regarding sensitivity for detecting liver metastases originating from pancreatic cancer for the current generation of MDCT scanners (64-detector row or better). Two studies that have compared 64-detector row MDCT with 3T MRI showed for CT a sensitivity of 70% to 76% in the detection of liver metastases compared to 90% to 100% for MRI with either gadobenate dimeglumine or gadoxetic acid [33,36]. Ikuta et al [37] studied 192 patients to compare 4-detector row multiphasic MDCT with CT arterial portography (CTAP) and computed tomography-assisted hepatic arteriography (CTHA) with intraoperative US as the gold standard in the assessment of those patients identified as not having metastatic disease. Of note, CTAP with CTHA is an invasive technique requiring a separate interventional procedure for placement of an arterial catheter to optimize contrast evaluation by CT, and as such is not practiced routinely. Furthermore, MDCT was performed with only four detectors, which is far less than many contemporary scanners.


Staging of Pancreatic Ductal Adenocarcinoma. In that study, MDCT had a sensitivity of 48.4% and specificity of 98% for liver metastases compared to CTAP + CTHA, which had a sensitivity of 94.2% and specificity of 82.7%. Although the results of CTAP + CTHA were impressive, the data regarding current state-of-the-art MDCT are not representative of modern practice. Peritoneal metastases from pancreatic cancer are typically difficult to identify by any of the modalities because of their typically small size or miliary appearance. In our literature search, no studies that tried to assess overall sensitivity for peritoneal metastases by CT were available, likely because patients were already found to have unresectable disease secondary to other causes such as liver metastases or extensive vascular involvement. Studies that were retrieved in our examination focused on the question of the additional usefulness of preoperative laparoscopic assessment following CT. Results have been controversial, but indirectly these provide information regarding whether CT is sufficient for detection of peritoneal disease for disease management. A meta-analysis of 1,015 patients across 15 studies concluded that, on average, out of 100 patients identified as having resectable disease based on CT, use of follow-up laparoscopy would have avoided 23 unnecessary laparotomies [38]. Another recent meta-analysis that analyzed 12 studies between 1999 and 2010 showed a pooled sensitivity of laparoscopic assessment of 75% for peritoneal implants [39]. In our anecdotal experience, institutions will variably use laparoscopy, sometimes in the setting of suspicion for peritoneal disease, but for some others more globally, with or without laparoscopic peritoneal washing, with the plan to proceed directly to laparotomy at the same setting for planned pancreatic resection in the absence of detection of peritoneal disease.


Staging of Pancreatic Ductal Adenocarcinoma. MRI The limitations noted above for studies regarding CT and the accuracy of assessing vascular involvement by tumor apply to MRI as well (with differences in criteria for defining a vessel as involved by tumor, differences in definitions of resectability, and varying generations of equipment, etc. ). Fewer studies are available on the topic of MRI and staging of pancreatic cancer than there are for CT. A study comparing 64-detector row MDCT versus 3T MRI showed for MRI a sensitivity for vascular infiltration of 50% to 80% and a specificity of 96% to 98% [11]. These findings are similar to those found on a meta-analysis of eight studies published between 1997 and 2004 that showed a pooled sensitivity of 67% and pooled specificity of 94% that was not significantly different Staging of Pancreatic Ductal Adenocarcinoma from CT [33]. Therefore, MRI and CT can be considered likely comparable with regard to assessment of vascular involvement by tumor. As noted above, assessment for nodal staging on cross-sectional imaging is limited because of its current inability to identify micrometastases. A critical review article on staging reportedly noted an accuracy ranging from 61% to 77% in radiology studies from 2004 to 2009 for the detection of nodal involvement by tumor [29]. In contrast, MRI has been shown to be likely superior for the detection of liver metastases. Two studies that compared 64-detector row MDCT with 3T MRI showed that CT had a sensitivity of 70% to 76% for the detection of liver metastases compared to 90% to 100% for MRI with either gadobenate dimeglumine or gadoxetic acid [33,36]. The literature search identified only very limited information with regard to MRI and pancreatic cancer peritoneal metastases. A study evaluating the usefulness of staging laparoscopy following staging MRI noted that the yield of staging laparoscopy was marginal and cost effectiveness was reportedly poor for use of this approach [40].


Staging of Pancreatic Ductal Adenocarcinoma. EUS EUS A recent meta-analysis of 29 studies that incorporated EUS showed EUS to have a pooled sensitivity of 85% and specificity of 91% for vascular invasion [41]. Notably, the same study noted that the criteria for identifying arterial invasion have not been standardized, which is a constraining factor when attempting to compare between modalities and likely accounts for the wide range of sensitivity for vascular invasion of EUS in this meta-analysis (62% to 100%). The authors noted in their review that there are little comparative data between arterial and venous assessments, and that overall it appeared that CT and EUS performed comparably for assessing venous involvement and that CT may be superior for the assessment of invasion of arterial structures [41]. With regard to nodal disease, EUS has the advantage in that it can be combined with FNA to greatly improve its specificity. A recent meta-analysis of 8 studies showed a pooled sensitivity of 58% and specificity of 85% for detecting nodal metastases with EUS alone [41]. Although the meta-analysis did not include an assessment of multiple studies with EUS that included FNA, the authors did note that EUS would likely improve nodal staging, and cited a study that reported a sensitivity of 82% and specificity of 100% to confirm malignant adenopathy [42]. Because of its narrow field-of-view, and the limited region of anatomic coverage, EUS does not have a role for assessment of peritoneal disease. EUS allows for a limited examination of the left liver lobe and possible FNA of these lesions. No studies have directly compared the accuracy of EUS and cross-sectional imaging for left-sided liver metastasis. Imaging of the right liver is difficult and unreliable by EUS. US Difficulties in visualizing the pancreas in detail because of either body habitus or commonly interposed bowel gas limit the usefulness of transabdominal US for staging.


Staging of Pancreatic Ductal Adenocarcinoma. FDG-PET/CT As noted earlier, there is considerable variability in how the CT portion of the examination is obtained for FDG- PET/CT with regard to whether IV or oral contrast is administered. When performed without IV contrast, it does not have a role in the assessment for potential vascular involvement. When performed with IV contrast enhancement, it is typically acquired as a single phase of contrast enhancement at variable slice thickness and variable reconstructed display field-of-view between institutions. These parameters would affect the usefulness and effectiveness of local staging. FDG-PET/CT, when used in the setting of preoperative staging, is therefore typically used as a whole-body examination for follow-up to contrast-enhanced CT or MRI, which themselves would already provide information regarding liver metastases, potential peritoneal implants, and possible adenopathy. This is likely why most of the studies retrieved in our literature search evaluated the usefulness of FDG-PET/CT as a follow-up study whole body examination to conventional cross-sectional imaging for the detection of unexpected distant metastases. One of the challenges encountered in evaluating the studies, is that often distant metastases (liver, peritoneal, lung, bone, nodes) were put together into a single group rather than subgroups by the type of distant metastasis. The results are variable across studies with the detection rate of unexpected distant metastases generally identified in patients as probably resectable based on contrast-enhanced CT or MRI, ranging from 2.5% to 41% [43-48]. A recent meta-analysis of FDG-PET/CT imaging (4 studies, 101 patients) showed a pooled sensitivity of 64% and specificity of 81% for metastatic nodal disease, and a sensitivity of 67% and specificity of 96% for liver metastases [49]. Staging of Pancreatic Ductal Adenocarcinoma Variant 2: Pancreatic ductal adenocarcinoma. Follow-up post-neoadjuvant therapy.


Staging of Pancreatic Ductal Adenocarcinoma. Evaluate resectability for borderline resectable tumor. Only five articles that addressed the topic of preoperative therapy in the context of staging a tumor were identified in the literature search. CT CT Only very limited information is available regarding staging in the setting of preoperative chemotherapy and/or radiation therapy. Challenges include differences in treatment regimens. A small study comparing 31 patients who had undergone neoadjuvant therapy (between 2005 and 2010) for locally advanced disease that went on to attempted curative resection with a control group of 41 patients who went directly to surgery showed that the accuracy of MDCT (in this study, 16- and 64-detector row) for determining resectability was significantly less in the neoadjuvant group (58% versus 83%), primarily secondary to an overestimation of vascular invasion [50]. This study was limited by a mix of treatment regimens including chemotherapy alone, radiation therapy alone, and combination chemoradiation. Other studies have also shown that imaging signs of vascular involvement by tumor persist even after successful therapy because of the inability of imaging to distinguish viable from nonviable tumor [51,52]. No information was available from our search in regard to the accuracy of identifying nodal metastases, liver metastases, or peritoneal disease in the setting of neoadjuvant therapy. MRI The literature search did not identify any studies that examined the accuracy of MRI in the assessment of staging following preoperative therapy. EUS The literature search did not identify any studies that examined the accuracy of EUS in the assessment of vascular involvement by tumor following neoadjuvant therapy. US The literature search did not identify any studies that examined the accuracy of transabdominal US in the assessment of vascular involvement by tumor following neoadjuvant therapy.


Staging of Pancreatic Ductal Adenocarcinoma. FDG-PET/CT The literature search did not identify any studies that examined the accuracy of FDG-PET/CT in the assessment of staging following neoadjuvant therapy. Reporting of Imaging Findings for Staging Pancreatic Cancer An emerging issue has been the reporting of findings for staging for pancreatic cancer by radiologists, namely, the usefulness of structured reporting or template reporting versus free-form (nonstructured) dictation. A single institution study had surgeons evaluate 48 structured and 72 nonstructured reports and found that information for surgical planning was readily accessible in 60% to 98% of structured reports, but only 32% to 54% in nonstructured reports [53]. In a retrospective study of 200 reports reviewed by radiologists, it was noted that in 20.3% of reports, resectability status could not be determined based on the report alone [54]. Although there are references that report on studies with design limitations, 16 well-designed or good-quality studies provide good evidence. Appropriateness Category Names and Definitions Relative Radiation Level Information Potential adverse health effects associated with radiation exposure are an important factor to consider when selecting the appropriate imaging procedure. Because there is a wide range of radiation exposures associated with different diagnostic procedures, a relative radiation level (RRL) indication has been included for each imaging examination. The RRLs are based on effective dose, which is a radiation dose quantity that is used to estimate population total radiation risk associated with an imaging procedure. Patients in the pediatric age group are at inherently higher risk from exposure, both because of organ sensitivity and longer life expectancy (relevant to the long latency that appears to accompany radiation exposure). For these reasons, the RRL dose estimate ranges for pediatric examinations are lower as compared to those specified for adults (see Table below). Additional


Back Pain Child PCAs

Back Pain Child PCAs.  Introduction/Background It is now generally accepted that nontraumatic back pain in the pediatric population is common. Evaluation of the spine in the setting of trauma will be addressed with a forthcoming ACR Appropriateness Criteria guideline. Early studies have reported prevalence as low as 2%, with more recent evidence suggesting that up to half of the pediatric population experiences back pain [1]. The incidence of back pain increases throughout childhood, most notably lower back pain [2]. Childhood back pain may be predictive of adult back pain [2]. Female sex, poor general health, high level of activity, backpack loads, and family history of back pain are risk factors that have been suggested [3]. Most pediatric back pain is mechanical and responds to conservative treatment with imaging not required in the clinical evaluation [1,4-6]. However, back pain may be caused by more serious conditions, including the broad categories of traumatic, infectious, inflammatory, congenital, and neoplastic processes [7,8]. Evaluation of scoliosis associated with pain will be addressed under a separate ACR Appropriateness Criteria guideline. Back pain is common in the pediatric athlete, with many potential etiologies [9]. The presence of isolated back pain in a child has previously been an indication for imaging; however, recently a more conservative approach has been suggested. As in adults, a diagnostic algorithm is suggested for evaluation of children with back pain in order to reduce the number of unnecessary examinations performed and resultant radiation exposure [10]. Children with back pain of short duration, a normal physical examination, and minor or no history of trauma will likely benefit little from further laboratory or imaging evaluation [1,8,11]. Imaging should be reserved for the presence of persistent back pain with concerning clinical and laboratory findings.


Back Pain Child PCAs

Back Pain Child PCAs. Laboratory evaluation with a complete blood count and sedimentation rate may be of use to evaluate for a systemic etiology [12-14]. Clinical and laboratory findings suggesting an infectious or neoplastic etiology should be imaged without delay. The presence of constant pain, night pain, and radicular pain, alone or in combination, lasting for 4 weeks or more, constitute clinical red flags that should prompt further imaging. An abnormal neurologic examination should prompt immediate imaging [1,4,5]. Overview of Imaging Modalities Radiographs Radiographs of the symptomatic region are a useful initial imaging modality, as they are readily available and may lead to a diagnosis in a significant number of patients [4]. Vertebral alignment, spinal curvature, and disc height can easily be ascertained using radiographs. The presence of spondylolysis, Scheuermann disease, and primary bone tumors may be suggested on radiographs and direct any further imaging [4,15,16]. Oblique views of the lumbar spine have been shown to double the radiation dose delivered without any additional helpful information beyond the standard frontal and lateral views [6,9]. Radiographs are insensitive to paraspinal and intraspinal soft-tissue masses. 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 Magnetic Resonance Imaging MRI without contrast has been shown to be an effective screening tool in evaluating pediatric patients with certain red-flag clinical presentations [1,5]. In young patients, the MRI examination may need to be performed under sedation. MRI is the only modality that directly visualizes the spinal cord, ligaments, and intervertebral discs.


Back Pain Child PCAs

Back Pain Child PCAs. T2- weighted images and fat-suppression techniques are necessary for evaluating for marrow edema and paraspinal pathology. MRI without contrast is often able to determine a cause of mechanical back pain, most commonly spondylolysis, with high sensitivity [22-24]. Recent studies have demonstrated MRI to be more sensitive than computed tomography (CT) and a potential first-line test in the evaluation of spondylolysis [23,24]. Fluid- sensitive and fat-suppressed MRI techniques are able to identify stress reaction (marrow edema) in the pedicles as well as spondylolisthesis, which are the 2 findings that guide management of these patients [22,24]. MRI is optimal for demonstrating degenerative disc pathology, which may be more common in the pediatric population than previously suspected [25,26]. The main advantage of MRI is optimal intraspinal and paraspinal soft-tissue evaluation. Intraspinal tumors can present with back pain and MRI is the indicated imaging modality in this subset of patients [27,28]. Osteomyelitis and epidural and paraspinal infection are well demonstrated on MRI and can guide surgical intervention [13,14,29]. Fat-suppressed T2 and T1 postcontrast MRI sequences such as short tau inversion recovery, Dixon, and fat-suppressed turbo spin echo are necessary for evaluation of suspected infectious or neoplastic disease involving the vertebrae, discs, or paraspinous soft tissues [8]. Computed Tomography CT without contrast provides excellent bone detail. The modality is suboptimal for evaluating the intraspinal contents and the paraspinal soft tissues in comparison with MRI. The ability of CT to reconstruct in multiple planes and perform 3D volume-rendered images is an advantage. CT targeted to the area of interest can be useful in the evaluation of suspected spondylolysis as well as primary bone tumors such as osteoid osteoma, osteoblastoma, and aneurysmal bone cyst [15,27,30]. However, CT does not demonstrate associated marrow edema.


Back Pain Child PCAs

Back Pain Child PCAs. Also, intrinsic fluid-fluid levels and associated soft-tissue abnormalities are better demonstrated on MRI. Apophyseal ring fractures are also well evaluated on CT [31]. CT with contrast can be considered when infection and abscess are suspected and MRI is contraindicated or not feasible. Myelography and Postmyelography Computed Tomography Spine The indication for myelography and postmyelography CT is narrow and limited because of its invasiveness and limited diagnostic yield. Myelography and postmyelography CT can be considered in conditions where intraspinal pathology is suspected and MRI is either contraindicated or will be significantly limited by existing hardware. Discussion of Imaging Modalities by Variant Variant 1: Child. Back pain with none of the following clinical red flags: constant pain, night pain, radicular pain, pain lasting >4 weeks, abnormal neurologic examination. Initial imaging evaluation. Radiographs There is little evidence that radiographic evaluation of the region of interest in acute uncomplicated back pain without an associated traumatic event is indicated [8,9,11,12]. MRI Spine MRI is not indicated in back pain without clinical red flags present [1,4,5]. If an inflammatory, infectious, or neoplastic process is suggested from initial clinical or laboratory evaluation, MRI without and with contrast of the complete spine is the suggested imaging modality in further imaging evaluation [8,27,28]. If contrast is administered, precontrast images are helpful to assess enhancement. There is little use for performing an MRI with contrast only. CT Spine CT is not indicated for evaluation of patients with back pain and no clinical red flags. If an inflammatory, infectious, or neoplastic process is suggested from initial clinical or laboratory evaluation and MRI cannot be obtained, a CT spine with contrast targeted to the area of interest may be indicated. CT spine without and with contrast is not indicated for evaluation of patients with back pain and no red flags.


Back Pain Child PCAs

Back Pain Child PCAs. Bone Scan Whole Body with SPECT or SPECT/CT Complete Spine SPECT bone scan is not indicated for evaluation of patients with back pain and no red flags. Myelography and Postmyelography CT Spine This examination is not indicated for evaluation of patients with back pain and no red flags. Variant 2: Child. Back pain with 1 or more of the following clinical red flags: constant pain, night pain, radicular pain, pain lasting >4 weeks, abnormal neurologic examination. Initial imaging evaluation. Radiographs Radiographs of the cervical, thoracic, or lumbar spine are a useful initial diagnostic imaging procedure for evaluation of back pain in children. Radiographs can demonstrate findings that lead to the diagnosis in up to 24% of children [1,4,5]. Anterior-posterior radiographs are typically sufficient, with additional views only adding to the radiation dose without increase in diagnostic yield. Collimation to the area of concern may aid in the diagnosis [6,9]. Pathologic conditions that can be diagnosed on radiographs include spondylolysis, scoliosis, Scheuermann disease, and bone tumors [1,4,5]. In children with back pain and clinical red flags, negative radiographs are not considered adequate to exclude pathology and additional advanced imaging techniques are required [1,5]. Positive radiographs leading to a specific diagnosis may guide therapy without additional imaging or direct further appropriate imaging evaluation [1,4,5]. MRI Spine Noncontrast MRI of the spine targeted to the region of interest is sensitive for the imaging evaluation of soft- tissue and bony abnormalities associated with pediatric back pain, including paraspinous soft-tissue pathology, disc disease, marrow edema, and intraspinal masses [8,24-26,32]. However, radiographs should be the initial imaging evaluation in most cases. MRI of the total spine may be indicated as the initial evaluation of patients with abnormal neurologic findings.


Back Pain Child PCAs

Back Pain Child PCAs. Contrast is helpful in the evaluation of back pain in children when there is clinical or laboratory evidence of infection, inflammation, or tumor [8,13,33]. If contrast is administered, precontrast images are helpful to assess enhancement. There is little use for performing an MRI with contrast only. CT Spine Bone lesions and fractures are well delineated on targeted noncontrast CT [7,15]. However, radiographs should be obtained initially. Although CT with contrast may be helpful when infection or tumor is suspected, MRI without and with contrast is the modality of choice in the evaluation of these patients. CT with contrast should be considered only when MRI is contraindicated or not feasible. CT both without and with contrast is not usually indicated. In the circumstance where there is a need to determine the presence of calcifications, limited noncontrast images could be obtained through the area of interest. Bone Scan Whole Body with SPECT or SPECT/CT Complete Spine Tc-99m bone scan may be a useful screening tool in children with back pain and no specific neurologic findings on physical examination [4]. However, radiographs should be the initial imaging examination and may direct further evaluation. Myelography and Postmyelography CT Spine Because of the invasiveness of the procedure, myelography and postmyelography CT of the whole spine are considered in the setting of an abnormal neurologic examination only if MRI is contraindicated or will have significantly limited diagnostic yield because of spinal hardware. Variant 3: Child. Back pain with 1 or more of the following clinical red flags: constant pain, night pain, radicular pain, pain lasting >4 weeks, abnormal neurologic examination. Negative radiographs. Children with negative radiographs and back pain associated with clinical red flags should undergo additional imaging evaluation.


Back Pain Child PCAs

Back Pain Child PCAs. MRI Spine MRI of the total spine is sensitive for the imaging evaluation of soft-tissue and bony abnormalities associated with pediatric back pain, including paraspinous soft-tissue pathology, disc disease, marrow edema, and intraspinal masses [8,24-26,32]. Nonneoplastic intraspinal etiologies of back pain such as syrinx and meningoceles are well demonstrated using MRI [34,35]. Two large prospective studies have used MRI in an algorithm for evaluation of pediatric back pain in a total of 348 patients [1,5]. These studies found that MRI had high diagnostic accuracy in identifying and delineating the etiology of pediatric back pain. MRI is especially useful in evaluation of children with positive neurologic findings and should be considered the primary imaging modality in this subset of patients. An imaging algorithm has been proposed that includes only MRI in the imaging evaluation of children with positive neurologic findings [4]. Contrast is helpful in the evaluation of back pain in children when there is clinical or laboratory evidence of infection, inflammation, or tumor [8,13,33]. If contrast is administered, precontrast images are helpful to assess enhancement. There is little use for performing an MRI with contrast only. MRI of the spine in the clinical setting of back pain should always be performed with fat-saturated imaging techniques, especially following the administration of contrast. CT Spine Fractures and bone lesions are well delineated on targeted noncontrast CT [7,15]. CT has been found to be complementary to bone scan in evaluation of spondylolysis [4,30]. CT with contrast can be used when infection or tumor is suspected; however, MRI without and with contrast is the modality of choice in the evaluation of these patients. CT with contrast targeted to the area of interest should be considered only when MRI is contraindicated or not feasible. Performing CT both without and with contrast is not usually indicated.


Back Pain Child PCAs

Back Pain Child PCAs. In the circumstance of determining the presence of calcifications, limited images could be obtained through the area of interest. Bone Scan Whole Body with SPECT or SPECT/CT Complete Spine Tc-99m bone scan may be a useful tool in children with back pain and no specific neurologic findings on physical examination [4]. However, a retrospective study evaluating bone scan as a screening tool found that primary malignancies of the spine were missed in 3 out of 142 patients, although only planar bone scans were obtained in this study [20]. Although bone scan with SPECT can be very sensitive to bone pathology such as spondylolysis [19], potentially significant causes of back pain could be missed using only this modality [8,20]. SPECT/CT is not addressed in this discussion because it is not widely available. Myelography and Postmyelography CT Spine Because of the invasiveness of the procedure, myelography and postmyelography CT of the whole spine are considered in the setting of an abnormal neurologic examination only if MRI is contraindicated or will have significantly limited diagnostic yield because of spinal hardware. Variant 4: Child. Back pain with 1 or more of the following clinical red flags: constant pain, night pain, radicular pain, pain lasting >4 weeks, abnormal neurologic examination. Positive radiographs. MRI Spine MRI is sensitive for the imaging evaluation of soft-tissue and bony abnormalities associated with pediatric back pain, including paraspinous soft-tissue pathology, disc disease, marrow edema, and intraspinal masses that may be suggested on radiographs of the spine [8,24-26,32]. Two large prospective studies have used MRI in an algorithm for evaluation of pediatric back pain in a total of 348 patients [1,5]. These studies found that MRI had high diagnostic accuracy in identifying and delineating the etiology of pediatric back pain; however, if a specific diagnosis was determined using spine radiographs, MRI was not performed.


Back Pain Child PCAs

Back Pain Child PCAs. MRI can confirm and further characterize abnormalities demonstrated on radiographs. MRI is especially useful in evaluation of children with positive neurologic findings. An imaging algorithm has been proposed that includes only MRI in the imaging evaluation of children with positive neurologic findings [4]. If contrast is administered, precontrast images are helpful to assess enhancement. Findings on spine radiographs such as disc-space narrowing, endplate irregularity, bone destruction, or widening of the spinal canal suggest an inflammatory, infectious, or neoplastic process [7,8]. MRI of the total spine without and with contrast is helpful in the evaluation of back pain in children with clinical or imaging evidence of infection, inflammation, or tumor [8,13,33]. There is little use for performing an MRI with contrast only. MRI of the spine in the clinical setting of back pain should always be performed with fat-saturated imaging techniques, especially following the administration of contrast. CT Spine Fractures and bone lesions may be suggested on radiographs of the spine. These entities may be better delineated and confirmed on targeted noncontrast CT [7,15]. CT has been found to be complementary to bone scan in evaluation of spondylolysis [4,30]. CT with contrast should be considered only when MRI is contraindicated or not feasible. Performing CT both without and with contrast is not usually indicated. In the circumstance of determining the presence of calcifications, limited noncontrast images could be obtained through the area of interest. Bone Scan Whole Body with SPECT or SPECT/CT Complete Spine Tc-99m bone scan may be a useful screening tool in children with back pain and no specific neurologic findings on physical examination [4]. Bone scan can confirm the presence of an abnormality suggested on radiographs, and because of the whole-body technique it has the ability to demonstrate additional osseous abnormalities (multifocality) as regions of increased radiotracer uptake [31,36]


Back Pain Child PCAs

Back Pain Child PCAs. Myelography and Postmyelography CT Spine Because of the invasiveness of the procedure, myelography and postmyelography CT of the total spine are considered in the setting of an abnormal neurologic examination only if MRI is contraindicated or will have significantly limited diagnostic yield because of spinal hardware. Variant 5: Child. Chronic back pain associated with overuse. Mechanical back pain. Radiographs The most common etiology for overuse-related chronic back pain in children is spondylolysis. Radiography of the symptomatic region of the spine is a useful screening tool for spondylolysis, with a sensitivity of 77.6% for anterior-posterior and lateral radiographs [6]. The combination of negative radiographs and a negative clinical examination was reported to have an 0.81 negative predictive value [21]. Additional views did not significantly increase sensitivity [6,9]. Other reports have suggested a lower sensitivity for diagnosing spondylolysis using radiographs as compared to MRI [24]. Other etiologies for chronic back pain, such as apophyseal ring fractures and Scheuermann disease, may be suggested with radiographs alone [31]. MRI Spine MRI can show edema in the region of the pars interarticularis or adjacent pedicle in spondylolysis with negative radiographs and CT. MRI is especially useful in detection of active spondylolysis and has been positively associated with clinical symptomatology [23,24]. Resolution of signal abnormalities suggests a response to therapy and potential prevention of progression to fracture [22,37]. It remains uncertain whether MRI or bone scan with SPECT is preferred in the evaluation of suspected spondylolysis [38]. Abnormalities on MRI such as apophyseal injuries, spondylolysis, and disc disease have been shown to be associated with back pain in the pediatric athlete [39].


Back Pain Child PCAs

Back Pain Child PCAs. MRI can evaluate radiculopathy elicited by both spondylolytic and nonspondylolytic causes and may demonstrate additional etiologies, including apophyseal fractures, intraspinous ligamentous injury, discogenic injury, Scheuermann disease, and compartment syndromes [8,31,40]. If contrast is administered, precontrast images are needed to assess enhancement. MRI of the spine in the clinical setting of back pain should always be performed with fat-saturated imaging techniques. There is little use for performing an MRI with contrast only. Contrast is not indicated in the evaluation of chronic back pain due to suspected mechanical causes. CT Spine CT is mostly considered an adjunct to other imaging modalities and has a high sensitivity in evaluation of spondylolysis [6]. CT is superior to radiographs in evaluation of spondylolysis, and with radiation dose-reduction techniques, a similar dose can be achieved [41]. CT has been shown to be complementary in the evaluation of pars interarticularis injuries and has the potential to direct further management [30]. Early stress reaction may be missed using CT alone without a bone scan or MRI [23,42]. Ring apophyseal injuries are also well demonstrated on CT [15,31]. CT spine with contrast is not indicated in mechanical back pain. Bone Scan Whole Body with SPECT or SPECT/CT Complete Spine There have been studies that have shown that bone scan with SPECT is a sensitive imaging technique for the evaluation of suspected spondylolysis at all ages [6,43,44]. Bone scan has been shown to be more sensitive in comparison to MRI for evaluation of active spondylolysis [19]. However, MRI may be able to detect disc pathology and other processes that can mimic or be associated with spondylolysis [32,40]. In chronic spondylolysis with wide separation and smooth margins, the bone scan may be negative [30]. On the other hand, bone scan can demonstrate increased uptake due to a stress reaction while CT reveals no abnormality [42].


Back Pain Child PCAs

Back Pain Child PCAs. Because of the whole-body technique, bone scan can demonstrate additional osseous abnormalities as regions of increased radiotracer uptake [31,36]. Myelography and Postmyelography CT Spine This examination is not indicated in the evaluation of chronic back pain due to suspected mechanical causes and normal neurologic examination. Variant 6: Child. Back pain associated with suspected inflammation, infection, or malignancy. Radiographs Radiography of the area of clinical interest can be suggestive of inflammatory, infectious, or malignant conditions affecting the spine; however, the modality is insensitive and can easily miss subtle findings [27,28]. Discogenic infections occur in the pediatric population and manifest as mild disc-space narrowing on radiographs [7]. Lytic or sclerotic primary and metastatic tumors may be identified along with evidence of bony destruction, periosteal reaction, or a soft-tissue mass. Subtle pedicular erosion with widening of the interpedicular distance or enlargement of the neural foramina may be secondary findings due to an intraspinal tumor [8]. MRI Spine If inflammation, infection, or malignancy is suspected, MRI without and with contrast of the total spine or region of interest is indicated. A noncontrast examination may be indicated in the presence of renal dysfunction. MRI is generally accepted as the primary imaging modality for the detection and evaluation of intra- and paraspinal masses [27,28]. The ability to localize the mass in relation to adjacent neural structures is a significant advantage over other imaging modalities [8]. Infectious spondyloarthropathies also are best imaged using MRI because of its ability to evaluate for epidural extension of disease and cord compromise [8,13,29]. MRI may also be able to differentiate tuberculous from nontuberculous spondylitis [14]. Additionally, inflammatory arthropathies are well evaluated with MRI [33]. If contrast is administered, precontrast images are needed to assess enhancement.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs.  Introduction/Background Cerebrovascular diseases encompass a range of varied clinical presentations and disease processes. This document focuses on clinical scenarios related to stroke and intraparenchymal hemorrhage (IPH), stroke-like conditions such as venous sinus thrombosis and arterial vascular dissection, and known vascular stroke-related risk factors such as cervical bruit and carotid stenosis. The clinical variants included in this document describe imaging management early in clinical presentation with acute or recent onset of symptoms, as well as ongoing imaging during management of known stroke and stroke-related conditions in the subacute and chronic phases. The subset of cerebrovascular diseases and presentations are broad and varied; therefore, the introduction and background of each variant will be discussed individually. Special Imaging Considerations In many stroke-related clinical scenarios, both parenchymal and vascular imaging procedures are commonly used, particularly in the initial imaging of acute clinical presentations. Noncontrast head CT can be performed rapidly, either alone or included in the performance of CT angiography (CTA) of the head. For the purposes of this document, both procedures are discussed separately for each variant, highlighting the individual usefulness of both the noncontrast examination and contrast-enhanced vascular imaging phase. CTA of the head and neck are often acquired together, using a single contrast bolus for optimal arterial vascular opacification. Although the diagnostic usefulness and/or acuity of intracranial and extracranial vascular assessment may differ within a particular clinical context, the benefit of combined neck and head vascular imaging may have added clinical benefit in circumstances in which transcatheter arterial intervention is a potential consideration.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI perfusion imaging is most commonly performed using intravenous (IV) contrast; however, newer scanners may also have the ability to perform noncontrast perfusion imaging without IV contrast using arterial spin-labeled (ASL) techniques. Future Appropriateness Criteria documents may consider this technique as it achieves greater adoption in routine clinical practice. aUniversity of California San Diego, San Diego, California. bPanel Chair, Atlanta VA Health Care System and Emory University, Atlanta, Georgia. cPanel Vice-Chair, Uniformed Services University, Bethesda, Maryland. dUniversity of Virginia Health System, Charlottesville, Virginia. eUniversity of Washington, Seattle, Washington and University of British Columbia, Vancouver, British Columbia, Canada. fYale University School of Medicine, New Haven, Connecticut; Committee on Emergency Radiology-GSER. gBarrow Neurological Institute, Phoenix, Arizona; Neurosurgery expert. hMayo Clinic, Rochester, Minnesota; Commission on Nuclear Medicine and Molecular Imaging. iWeill Cornell Medical College, New York, New York. jUniversity of Chicago, Chicago, Illinois. kWashington State University, Spokane, Washington; American College of Physicians. lSentara Norfolk General Hospital/Eastern Virginia Medical School, Norfolk, Virginia; American College of Emergency Physicians. mAlbany ENT & Allergy Services, PC, Albany, New York; American Academy of Otolaryngology-Head and Neck Surgery. nAlbert Einstein College of Medicine Montefiore Medical Center, Bronx, New York, Primary care physician. oStanford University School of Medicine, Stanford, California. pUniformed Services University of the Health Sciences, Bethesda, Maryland, Naval Medical Center Portsmouth, Portsmouth, Virginia. qUniversity of Colorado School of Medicine, Aurora, Colorado. rUniversity of Cincinnati Medical Center, Cincinnati, Ohio. sSpecialty Chair, Montefiore Medical Center, Bronx, New York.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. 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 OR Discussion of Procedures by Variant Variant 1: Adult. Clinical transient ischemic attack (TIA). Symptoms resolved. Initial imaging. Transient ischemic attacks (TIA) are self-limited focal neurologic deficits resulting from a temporary interruption in blood supply to the brain, with no permanent clinical deficit or demonstrated infarct on subsequent imaging. In the United States, the incidence of TIA is approximately 1.2 per 1,000 [7]. The traditional time-based definition of TIA set the maximum duration at 24 hours. A newer imaging-based definition restricts the term TIA to those without neuroimaging evidence of tissue damage. Practically, those with and without tissue damage are considered together for diagnosis and management proposes [8,9]. Although symptoms may resolve within a short period of time, typically <1 hour, the risk for subsequent stroke is high: 8.8% at 7 days and 11.6% at 90 days [10]. In the setting of symptomatic carotid disease, the 90-day risk of ipsilateral stroke is 20.1% [11]. Given the high risk for stroke following TIA, expeditious initial imaging is important. There is a direct correlation between the risk of stroke following a carotid territory TIA or minor stroke and degree of carotid stenosis, and this drives the decision for carotid endarterectomy (CEA) or stenting [12,13]. Therefore, evaluation of patients with clinical carotid TIA or minor stroke requires rapid vascular imaging of the cervical carotid arteries [12,13] in addition to brain parenchymal imaging.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Arteriography Cervicocerebral Although the spatial resolution of catheter-directed cerebral angiography is higher than any noninvasive technique, cerebral angiography is not preferred as an initial test due to the invasive nature and the diversity of etiologies for TIA. Cerebral angiography may be indicated later in the diagnostic pathway as a secondary examination in the workup of TIA, depending on the suspected underlying etiology and potential indications for endovascular therapy (EVT). CT Head Perfusion With IV Contrast CT perfusion (CTP) can identify abnormalities in the setting of TIA in up to one-third of cases. The detection of an underlying perfusion abnormality may be helpful for risk stratification [14-16]. Specific instances arise in patients with complete extracranial internal carotid artery occlusion in whom CTP can be used to determine its hemodynamic effect [17]. However, selection of patients with carotid occlusion for revascularization based on hemodynamic compromise does not improve outcome [18]. Therefore, CTP is not typically used for the initial assessment of TIA. CT Head With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the evaluation of TIA. CT Head Without and With IV Contrast There is no relevant literature to support the use of CT of the head without and with IV contrast in the evaluation of TIA. CT Head Without IV Contrast Noncontrast CT of the head is useful in the initial evaluation of TIA to exclude alternative etiologies and to evaluate for early ischemic changes. Many other lesions may mimic the symptoms of a TIA including intracranial hemorrhage (ICH), infection, and intracranial masses [14,19,20]. Most importantly, ICH must be excluded because it is a contraindication to administration of tissue thrombolytic agents, anticoagulants, and antiplatelet agents used to treat and prevent both TIA and stroke [13].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Moreover, the extent of ischemic changes seen on noncontrast CT, regardless of chronicity, is correlated with the risk of subsequent strokes [21]. Cerebrovascular Diseases-Stroke CTA Head With IV Contrast CTA of the head is a rapid means of evaluating the intracranial vasculature for underlying intracranial atherosclerosis and other intracranial steno-occlusive diseases, which may be useful in the secondary workup and triage of patients presenting with TIA. The identification of atherosclerotic intracranial vascular lesions in the setting of TIA may be useful in determining the most appropriate treatment options, although this is controversial [22,23]. CTA Neck With IV Contrast CTA of the neck is a rapid means of evaluating the extracranial vasculature and is useful in the initial workup and triage of patients presenting with carotid territory TIA. Current American Heart Association (AHA) guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting within 48 hours of onset [12]. Heavy calcifications or calcified plaque on both sides of the lumen can lead to overestimation of the stenosis [24]. CTV Head With IV Contrast There is no relevant literature to support the use of CT venography (CTV) head in the evaluation of TIA in the absence of suspicion for cerebral venous thrombosis (CVT). Please see Variant 7 for further details. MRA Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MR angiography (MRA) of the head in the evaluation of TIA. MRA Head Without IV Contrast MRA of the head is an alternative means of evaluating intracranial steno-occlusive disease and may be useful in the initial workup and triage of patients presenting with TIA.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Owing to the relatively rapid and noninvasive nature of the examination obviating the need for IV contrast, MRA may be preferable to CTA in patients with renal impairment, x-ray contrast allergy, or repeat presentations. Typically, noncontrast time-of-flight (TOF) MRA technique is sufficiently sensitive to screen for culprit intracranial lesions in the setting of suspected TIA [25]. MRA Neck Without and With IV Contrast MRA of the neck may be useful in screening for extracranial vascular disease in the initial workup and triage of patients presenting with TIA. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting, within 48 hours of onset [12]. Noncontrast MRA of the neck tends to overestimate the degree of carotid stenosis when compared with contrast- enhanced MRA, particularly in cases of high-grade stenosis [26]. Typically, noncontrast TOF MRA technique is sufficiently sensitive to screen for culprit intracranial lesions in the setting of suspected TIA [27]. MRA Neck Without IV Contrast MRA of the neck may be useful in screening for extracranial vascular disease in the initial workup and triage of patients presenting with TIA. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting, within 48 hours of onset [12]. Noncontrast MRA of the neck tends to overestimate the degree of carotid stenosis when compared with contrast- enhanced MRA, particularly in cases of high-grade stenosis [26]. Typically, noncontrast TOF MRA technique is sufficiently sensitive to screen for culprit intracranial lesions in the setting of suspected TIA [27].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Perfusion With IV Contrast Contrast-enhanced MRI head perfusion imaging (or, if available, noncontrast ASL perfusion) may detect additional abnormalities not identified on initial vascular imaging or diffusion-weighted imaging (DWI) in some patients presenting with TIA. Either technique may be useful in the secondary workup and triage of patients presenting with TIA depending on the suspected underlying etiology, particularly if no abnormalities are identified on direct vascular or parenchymal imaging studies [28-30]. Specific instances arise in patients with complete extracranial internal carotid artery occlusion in whom MR perfusion can be used to determine its hemodynamic effect [31-33]. However, selection of patients with carotid occlusion for revascularization based on hemodynamic compromise does not improve outcome [18]. MRI Head Without and With IV Contrast Noncontrast MRI head is typically sufficient for the routine assessment of uncomplicated TIA. Conditions rarely mimicking TIA include tumors and cerebral convexity subarachnoid hemorrhage due to amyloid angiopathy. MRI Cerebrovascular Diseases-Stroke without and with IV contrast may be helpful in the secondary workup of patients presenting with transient focal neurological symptoms [34]. MRI Head Without IV Contrast Owing to the relatively rapid noninvasive nature of MRI and the high sensitivity of DWI for ischemic change, MRI is the most sensitive test for acute infarct. MRI of the head may be useful in the initial or secondary evaluation of TIA to evaluate for ischemic changes on DWI or for other alternative etiologies [34,35]. MRI is particularly useful prognostically as an initial test in the setting of complete resolution of associated symptoms before presentation or shortly after presentation [29]. Additionally, MRI may be useful as an initial test on repeat clinical presentation [36].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRV Head Without and With IV Contrast There is no relevant literature to support the use of MR venography (MRV) of the head in the evaluation of TIA in the absence of suspicion of CVT, which can rarely present as a TIA [37]. MRV Head Without IV Contrast There is no relevant literature to support the use of MRV of the head in the evaluation of TIA in the absence of suspicion of CVT, which can rarely present as a TIA [37]. US Duplex Doppler Carotid Artery Ultrasound (US) duplex carotid Doppler is a useful test in the initial evaluation of the extracranial vasculature in the workup of TIA. Carotid Doppler US is noninvasive and is accurate in evaluating the degree of carotid stenosis [38]. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting within 48 hours of onset [12]. US Duplex Doppler Transcranial Transcranial Doppler can be used for the detection of microembolic events and in the detection of intracranial vascular pathology in the secondary workup of TIA. However, this is not typically used as an initial imaging test in the setting of TIA. Arteriography Cervicocerebral Cerebral angiography has the highest spatial and temporal resolution of any vascular imaging study. Due to the invasive nature of catheter-directed angiography, other modalities are typically preferred in the initial workup for stroke. However, in the setting of highly suspected LVO with no need for perfusion imaging or MRI to determine eligibility for EVT, initial catheter angiography after noncontrast CT may be the preferable vascular imaging study due to the ability to rapidly convert a diagnostic catheter angiogram to EVT [53,54].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. More specifically, patients presenting with suspicious signs on noncontrast CT such as hyperdense middle cerebral artery sign with a clear etiology for the LVO such as new onset atrial fibrillation may benefit from proceeding directly to angiography, although prospective data are limited in this regard [55]. Cerebrovascular Diseases-Stroke CT Head Perfusion With IV Contrast Within the initial 6-hour window of presentation of an acute stroke, CTP of the head is usually not necessary as an initial examination; conversely, delay, created by obtaining and analyzing CTP in the setting of a known LVO patient who is a clear EVT candidate, may be harmful [13,56]. In contrast, determining eligibility for EVT for anterior circulation strokes due to LVO confirmed on CTA presenting in the extended window of 6 to 24 hours may require or be determined by CTP or MR perfusion imaging in some cases [46,57]. Although a major RCT showing benefit of EVT 6 to 24 hours after onset permitted eligibility based on DWI-MRI or CTP [46], the rapidity of diagnosis afforded by CTP is a strongly relevant clinical consideration in this situation in most settings. CT Head With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the evaluation of ischemic stroke. CT Head Without and With IV Contrast There is no relevant literature to support the use of CT of the head without and with IV contrast in the evaluation of ischemic stroke. CTA Head With IV Contrast CTA of the head is the most rapid means of assessment of the intracranial vasculature for LVO in the setting of stroke. CTA of the head has a high sensitivity and specificity for the detection of intracranial LVO [60]. Stroke, possibly due to LVO, is a true medical emergency in which the rapidity of diagnosis afforded by CTA is a strongly relevant clinical consideration.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. The use of CTA of the head for the initial test in the detection of LVO is supported by multiple RCTs and is the preferred means of LVO detection due to the time-sensitive nature of stroke care [44,46,48,49,57]. Moreover, in the absence of an LVO, other etiologies such as atherosclerosis, vasculitis, reversible cerebral vasoconstrictive syndrome, or other etiologies may be suggested by CTA of the head. CTA Neck With IV Contrast CTA of the neck is the most rapid means of assessment of the extracranial vasculature in the setting of stroke. CTA of the neck can be rapidly acquired together with CTA of the head, can further elucidate the etiology of the stroke, and may be useful for endovascular surgical planning for EVT in LVO [13]. Specifically, the degree of vascular tortuosity is directly correlated with the time from groin puncture to recanalization and must be factored into the decision-making process both with regards to indications and surgical approach, including the choice of access using radial artery or direct carotid puncture approach [61]. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting, within 48 hours of onset [12]. CTV Head With IV Contrast There is no relevant literature to support the use of CTV head in the evaluation of suspected ischemic stroke in the absence of suspicion for CVT. MRA Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRA of the head in the evaluation of suspected ischemic stroke. MRA Head Without IV Contrast Although sensitive and specific in the detection of LVO, TOF MRA of the head may delay EVT in the setting of stroke due to LVO, which possibly detracts from the usefulness of this procedure due to the potential harm of delayed treatment [39,56].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Stroke due to LVO is a true medical emergency in which the rapidity of diagnosis afforded by CTA is a strongly relevant clinical consideration. In patients with renal insufficiency or x-ray contrast Cerebrovascular Diseases-Stroke allergy, TOF MRA can be used to identify arterial occlusions without putting the patient at risk and inform subsequent therapeutic decisions [52]. MRA Neck Without and With IV Contrast Although sensitive and specific in the detection of extracranial vascular disease and delineation of anatomy, MRA of the neck may delay EVT in the setting of stroke due to LVO, which possibly detracts from the usefulness of this procedure due to the potential harm of delayed treatment [39,56]. Stroke due to LVO is a true medical emergency in which the rapidity of diagnosis afforded by CTA is a strongly relevant clinical consideration. In patients with renal insufficiency or x-ray contrast allergy, TOF MRA can be used to delineate arterial anatomy without putting the patient at risk and inform subsequent therapeutic decisions [52]. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting, within 48 hours of onset [12]. MRA Neck Without IV Contrast Although sensitive and specific in the detection of extracranial vascular disease and delineation of anatomy, MRA of the neck may delay EVT in the setting of stroke due to LVO, which possibly detracts from the usefulness of this procedure due to the potential harm of delayed treatment [39,56]. Stroke due to LVO is a true medical emergency in which the rapidity of diagnosis afforded by CTA is a strongly relevant clinical consideration. In patients with renal insufficiency or x-ray contrast allergy, TOF MRA can be used to delineate arterial anatomy without putting the patient at risk and inform subsequent therapeutic decisions [52].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Perfusion With IV Contrast MRI head perfusion is sensitive and specific in the detection of reversible ischemia. MRI head perfusion may delay EVT in the setting of stroke due to LVO, which detracts from the usefulness of this study in the acute phase due to the potential harm of delayed treatment [39]. Although major RCTs showing benefit of EVT 6 to 24 hours after onset permitted eligibility based on MRI perfusion or CTP [46,57], the rapidity of diagnosis afforded by CTP is a strongly relevant clinical consideration in this situation in most settings. MRI Head Without and With IV Contrast Rarely, brain tumors or other conditions can mimic ischemic stroke. MRI without and with IV contrast may be helpful in the secondary workup of patients presenting with stroke-like symptoms [62]. MRI Head Without IV Contrast Although sensitive and specific in the detection of the extent of irreversible ischemia, MRI head may delay EVT in the setting of stroke due to anterior circulation LVO, which detracts from the usefulness of this study due to the potential harm of delayed treatment [39,46,56]. Although a major RCT showing benefit of EVT 6 to 24 hours after onset permitted eligibility based on DWI-MRI or CTP [46], the rapidity of diagnosis afforded by CTP is a strongly relevant clinical consideration in this situation in most settings. Similarly, the 2 positive RCTs for EVT in basilar occlusion used pc-ASPECTS from either DWI-MRI or noncontrast CT for eligibility. The rapidity of CT makes it preferable in this situation as well [48,49]. However, for some wake-up strokes and for some anterior circulation strokes with large infarcts, DWI-MRI and fluid-attenuated inversion recovery (FLAIR) sequences are necessary to determine eligibility for thrombolytics and EVT, respectively [40,47].