Major Blunt Trauma

Major Blunt Trauma. Unstable pelvic fractures, such as vertical shear and AP compression injury, are associated with higher rates of active hemorrhage, which can be accurately diagnosed by CTA and may require either surgical or vascular interventional treatment [27]. MRI Abdomen and Pelvis Blunt abdominal trauma is not typically evaluated by MRI because of the time of acquisition. However, some sites are moving toward the use of MRI in selected patients [28]. US Abdomen Although US may be able to diagnose certain abdominal injuries, its relatively lower specificity compared with CT does not make it a sufficient test to fully exclude abdominal injuries [29]. Bowel injury is a specific setting for which US is limited because of bowel gas. US FAST Scan Chest Abdomen Pelvis The role of FAST is primarily one of triage; a positive FAST and signs of hemodynamic instability may lead to immediate surgical intervention rather than CT. Although US may be able to diagnose certain thoracic and abdominal injuries, its relatively lower specificity compared with CT does not make it a sufficient test to exclude injuries to these areas [5]. US is not well suited for evaluation of bowel injury because significant fluid trapped in the mesentery may not be detected by FAST. Radiography Trauma Series Trauma series radiographs typically consist of portable radiographs of the chest and pelvis. A portable AP chest radiograph helps screen for immediately life-threatening findings, such as tension pneumothorax and significant mediastinal injury, as well as confirms line placement [13]. A portable radiograph of the pelvis can evaluate for unstable pelvic injuries and hip dislocation [4]. There is no literature to support the use of trauma series radiographs in the detection of bowel injury. Variant 6: Major blunt trauma. Hemodynamically stable. Suspected urinary system, including urethra trauma. Initial imaging.


Major Blunt Trauma

Major Blunt Trauma. CT Abdomen and Pelvis For blunt trauma, CT of the abdomen and pelvis with IV contrast is recommended, in the portal venous phase, 70 seconds after contrast administration for ideal characterization of solid organ injury, including the genitourinary system. This may be obtained in conjunction with CTA if there is a concern for renal infarction or arterial injury, as well as delayed imaging of the abdomen and pelvis if perinephric fluid suggests renal pelvis or ureteral trauma. The administration of oral contrast material has not been found to alter the sensitivity or specificity for blunt abdominal injuries and is not recommended because it can delay definitive diagnosis of other injuries [25]. Noncontrast CT of the abdomen and pelvis should ideally be avoided if there is no contraindication to IV contrast because of its lower sensitivity for detecting both visceral organ and vascular injuries [19]. CT Urography There is no relevant literature to support the use of CTU in the initial evaluation of patients who are hemodynamically stable with suspected urinary system or urethral trauma. CT Pelvis with Bladder Contrast (CT Cystography) Gross hematuria in the setting of blunt traumatic injury necessitates further evaluation with CT cystogram [30]. Urinary bladder injury typically occurs because of trauma to a distended urinary bladder and may or may not be accompanied by pelvic fractures. The absence of gross hematuria generally excludes the possibility of urinary bladder injury [31]. Deck et al [32,33] reported sensitivities of 95% overall but only 78% for intraperitoneal rupture. In another study with 100% sensitivity and 99% specificity for intraperitoneal bladder rupture, the specific sites of Major Blunt Trauma dome injuries in 4 of 18 patients were identified only with multiplanar reconstructed images [34]. A bladder contusion may not be visible by CT cystography.


Major Blunt Trauma

Major Blunt Trauma. Routine CT, using excreted contrast only, cannot be relied on entirely to diagnose bladder rupture, even with a urethral catheter inserted and clamped [35-37]. CT performed with excreted contrast only can demonstrate intraperitoneal or extraperitoneal fluid, but it cannot differentiate urine from ascites. However, the absence of pelvic ascites is strong evidence against an intraperitoneal bladder rupture [38,39]. As with IV urography (IVU), the bladder is usually inadequately distended to cause extravasation through a bladder laceration or perforation during routine abdominal and pelvic studies. A negative study does not exclude bladder injury [40]. Although CT is not the technique of choice for urethral injuries, it is performed so frequently that urethral injuries are often identified when CT is performed for pelvic trauma. CT Whole Body No practice consensus or validated decision rules currently exist for deciding which patients should receive WBCT versus selective CT imaging of the abdomen and pelvis for blunt trauma. Some studies have found a survival benefit to WBCT compared with selective CT [14], whereas others have found no mortality benefit [15]. Meta-analyses have found conflicting results with respect to improvements in mortality [16-18]. Therefore, clinical judgement remains vital for determining which patients should obtain selective CT versus WBCT. Indications that may warrant WBCT imaging as defined above include high-velocity (>35 mph) MVC, MVC resulting in rollover or passenger ejection, motorcycle trauma, bicycle injury, MVC-pedestrian collision, and a fall from a height of >15 feet. Additional considerations include patient age and functional status, hemodynamic stability, neurological status, and results of initial imaging from portable radiographs of the chest and pelvis, and/or FAST.


Major Blunt Trauma

Major Blunt Trauma. CT of the chest, abdomen, and pelvis with IV contrast have greater sensitivity for detecting visceral organ and vascular injury compared with noncontrast CT, and contrast-enhanced CT of these areas should be primarily considered unless absolutely contraindicated [19,20]. Patients who have an abnormal chest radiograph in the setting of trauma have clinically significant rates of major injury on CT chest [8]. CTA Abdomen and Pelvis CTA of the abdomen and pelvis may be performed to assess for active arterial bleeding. CTA of the abdomen has been shown to detect splenic vascular injuries more often than CT of the abdomen in the portal venous phase alone [26]. However, arterial phase imaging without 3-D reformations can also detect bleeding. Unstable pelvic fractures, such as vertical shear and AP compression injury, are associated with higher rates of active hemorrhage and may require either surgical or vascular interventional treatment [27]. MRI Abdomen and Pelvis There is no relevant literature to support the use of MRI of the abdomen and pelvis in the initial evaluation of patients who are hemodynamically stable with suspected urinary system or urethral trauma. MR Urography There is no relevant literature to support the use of MRU in the initial evaluation of patients who are hemodynamically stable with suspected urinary system or urethral trauma. US Abdomen and Pelvis Although US may be able to diagnose certain abdominal injuries, its relatively lower sensitivity compared with CT does not make it a sufficient test to exclude abdominal injuries [29,41,42]. Extraperitoneal and genitourinary injuries are more likely to be missed than intraperitoneal injuries [41,42]. US FAST Scan Chest Abdomen Pelvis The role of FAST is primarily one of triage; a positive FAST and signs of hemodynamic instability may lead to immediate surgical intervention rather than CT.


Major Blunt Trauma

Major Blunt Trauma. Although US may be able to diagnose certain thoracic and abdominal injuries, its relatively lower sensitivity compared with CT does not make it a sufficient test to exclude injuries to these areas, particularly extraperitoneal or genitourinary injuries [5,41,42]. In a series of 128 acute trauma patients, 11 of 19 injuries that were missed by emergent US involved the genitourinary system [41]. The detection of peritoneal fluid in the presence of normal viscera or the failure to visualize the bladder after the transurethral introduction of saline is considered highly suggestive of bladder rupture [35]. As a practical matter, US is not definitive in bladder or urethral trauma and is almost never used for this indication. Radiography Intravenous Urography There is no relevant literature to support the use of IVU in patients who are hemodynamically stable with suspected urinary system or urethral trauma. IVU has a low accuracy, on the order of 15% to 25% [43]. In one study, an Major Blunt Trauma accurate diagnosis of bladder rupture was made with IVU in only 5 of 23 (22%) patients [44]. Carroll and McAninch [45] found an accurate diagnosis for only 5 of 32 (16%) patients, and Werkman et al [46] found an accuracy rate for only 4 of 11 (36%) patients. Fluoroscopy Retrograde Urethrography In a male, gross blood at the urethral meatus may indicate a urethral injury, which warrants further evaluation with a retrograde urethrogram to evaluate urethral integrity [47]. Radiography Trauma Series Trauma series radiographs typically consist of portable radiographs of the chest and pelvis. A portable radiograph of the pelvis can evaluate for unstable pelvic injuries and hip dislocation [4]. A pelvic injury is associated with genitourinary trauma. A portable AP chest radiograph helps screen for immediately life-threatening findings, such as tension pneumothorax and significant mediastinal injury, as well as confirms line placement [13]. Variant 7: Major blunt trauma. Hemodynamically stable.


Major Blunt Trauma

Major Blunt Trauma. Suspected chest trauma. Initial imaging. CT Chest Noncontrast CT of the chest can detect most injuries, including rib fractures, pneumothorax, hemothorax, and pulmonary contusion, but has a lower sensitivity for detecting vascular injuries [20]. Contrast-enhanced CT of the chest is the preferred imaging workup of suspected chest trauma. Regardless of contrast administration, CT is more sensitive and specific for chest trauma than conventional radiographs [48,49]. Patients who have an abnormal chest radiograph in the setting of trauma have clinically significant rates of major injury on CT chest [8]. CT Whole Body Currently, there is no practice consensus or validated decision rules for deciding which patients should receive WBCT versus selective chest CT imaging for blunt trauma with concern for a chest injury. Some studies have found a survival benefit to WBCT compared with selective CT [14], whereas others have found no mortality benefit [15]. Meta-analyses have found conflicting results with respect to improvements in mortality [16-18]. Therefore, clinical judgement remains vital for determining which patients should obtain selective CT versus WBCT. Indications that may warrant WBCT imaging as defined above include high-velocity (>35 mph) MVC, MVC resulting in rollover or passenger ejection, motorcycle trauma, bicycle injury, MVC-pedestrian collision, and a fall from a height of >15 feet. Additional considerations include patient age and functional status, hemodynamic stability, neurological status, and results of initial imaging from portable radiographs of the chest and pelvis, and/or FAST. CT of the chest, abdomen, and pelvis with IV contrast have greater sensitivity for detecting visceral organ and vascular injury compared with noncontrast CT, and contrast-enhanced CT of these areas should be primarily considered unless absolutely contraindicated [19,20].


Major Blunt Trauma

Major Blunt Trauma. CTA Chest CT of the chest is warranted in the arterial phase primarily when there is a concern for aortic or other major vessel injury [20]. A delayed scan may be obtained, depending on the findings on the arterial phase CT. US Chest There is no relevant literature to support the use of non-US FAST of the chest in patients who are hemodynamically stable with suspected chest trauma. Its use in detection of pleural fluid and pneumothorax is increasing, but it has not gained acceptance for comprehensive evaluation of blunt chest trauma because of its lack of sensitivity for pulmonary, aortic, cardiac, and musculoskeletal injury [49]. US FAST Scan Chest Abdomen Pelvis The role of FAST is primarily one of triage; a positive FAST and signs of hemodynamic instability may lead to immediate surgical intervention rather than CT. Although US may be able to diagnose certain thoracic and abdominal injuries, its relatively lower specificity compared with CT does not make it a sufficient test to exclude injuries to these areas [5]. Its use in detection of pleural fluid and pneumothorax is increasing, but it has not gained acceptance for a comprehensive evaluation of blunt chest trauma because of its lack of sensitivity for pulmonary, aortic, cardiac, and musculoskeletal injury. Radiography Trauma Series Trauma series radiographs typically consist of portable radiographs of the chest and pelvis. In a patient with suspicion of chest trauma, a rapid assessment with chest radiographs plays a key role in initial workup. A portable AP chest radiograph helps screen for immediate life-threatening findings, such as tension pneumothorax and Major Blunt Trauma A portable radiograph of the pelvis can evaluate for unstable pelvic injuries and hip dislocation [4]. Compared with CT, pelvic radiographs also have lower sensitivity for detecting injury. In a study of 509 consecutive trauma patients, the sensitivity of the AP pelvic radiographs was 77% using CT as the reference standard [53].


Major Blunt Trauma

Major Blunt Trauma. The most common injury misses were the ones to the sacrum, sacroiliac joints, and loose bodies in the hip joints. MRI Chest There is no relevant literature to support the use of MRI for the initial evaluation of blunt chest trauma. It is not routinely performed because of the time required in the emergent setting. Use of MRI is mainly reserved for problem solving of findings identified on initial imaging studies. Variant 8: Major blunt trauma. Hemodynamically stable. Pregnant patient. Initial imaging. CT Abdomen and Pelvis For blunt trauma in a pregnant woman, CT of the abdomen and pelvis with IV contrast may still be recommended when there is a life-threatening concern for the mother or fetus. The study is typically performed in the portal venous phase, 70 seconds after contrast administration, for ideal characterization of solid organ injury. This may be obtained in conjunction with CTA as well as delayed imaging of the abdomen and pelvis. The administration of oral contrast material has not been found to alter the sensitivity or specificity for blunt abdominal injuries and is not recommended because it can delay definitive diagnosis of other injuries [25]. Noncontrast CT of the abdomen and pelvis should ideally be avoided because of its lower sensitivity for detecting both visceral organ and vascular injuries [19]. CT Whole Body Risks and benefits must be specifically weighed regarding CT imaging of the pregnant patient. No practice consensus or validated decision rules currently exist for deciding which patients should receive WBCT versus selective CT imaging for blunt trauma. Some studies in nonpregnant patients have found a survival benefit to WBCT compared with selective CT [14], whereas others have found no mortality benefit [15]. Meta-analyses have found conflicting results with respect to improvements in mortality [16-18]. Therefore, clinical judgement remains vital for determining which patients should obtain selective CT versus WBCT.


Major Blunt Trauma

Major Blunt Trauma. Indications that may warrant WBCT imaging as defined above include high-velocity (>35 mph) MVC, MVC resulting in rollover or passenger ejection, motorcycle trauma, bicycle injury, MVC-pedestrian collision, and a fall from a height of >15 feet. Additional considerations include patient age and functional status, hemodynamic stability, neurological status, and results of initial imaging from portable radiographs of the chest and pelvis, and/or FAST. CT of the chest, abdomen, and pelvis with IV contrast has greater sensitivity for detecting visceral organ and vascular injury compared with noncontrast CT, and contrast-enhanced CT of these areas should be primarily considered unless absolutely contraindicated [19,20]. Patients who have an abnormal chest radiograph in the setting of trauma have clinically significant rates of major injury on CT chest [8]. CTA Abdomen and Pelvis CTA may be carried through the abdomen and pelvis to assess for active arterial bleeding to abdominopelvic viscera and soft tissues. CTA of the abdomen has been shown to detect more splenic vascular injuries than CT of the abdomen in the portal venous phase alone [26]. Unstable pelvic fractures, such as vertical shear and AP compression injury, are associated with higher rates of active hemorrhage and may require either surgical or vascular interventional treatment [27]. Major Blunt Trauma CTA Chest CTA of the chest is warranted in the arterial phase primarily to assess for aortic or other major vessel injury, in addition to other injuries within the chest [20]. Noncontrast CT of the chest should be avoided because of its lower sensitivity for detecting vascular injuries [20]. MRI Abdomen and Pelvis There is no relevant literature to support the use of MRI abdomen and pelvis in patients who are hemodynamically stable and pregnant.


Shoulder Pain Traumatic PCAs

Shoulder Pain Traumatic PCAs.  Introduction/Background Traumatic shoulder pain is shoulder pain believed to be directly attributed to a traumatic event, either acute or chronic. This pain may be the result of either fracture (the clavicle, scapula, or proximal humerus) or soft-tissue injury (most commonly of the rotator cuff, acromioclavicular ligaments, or labroligamentous complex). The incidence of traumatic shoulder injuries is difficult to determine because some injury types, such as low-grade acromioclavicular separations or acute rotator cuff tears, are likely under-reported because patients do not seek immediate medical treatment. However, as with many traumatic injuries, traumatic shoulder pain tends to disproportionately involve young adults and male patients [1,2]. The etiology of traumatic shoulder pain can often be made based on clinical examination, radiographs, and mechanism of injury. Traumatic shoulder injuries can generally be separated into injuries requiring acute surgical management and injuries in which conservative management can be attempted prior to considering surgical treatment. Unstable or significantly displaced fractures and joint instability are injuries most likely requiring acute surgical treatment. Most soft-tissue injuries (such as labral tears and rotator cuff tears) can undergo a period of conservative management prior to considering surgery. However, in addition to the specific imaging findings related to a traumatic injury, indications and timing of surgical treatment of many traumatic shoulder injuries are dependent on patient age, comorbidities, current activity level, and expected activity level. Discussion of Procedures by Variant Discussion of Procedures by Variant Variant 1: Traumatic shoulder pain. Any etiology. Initial imaging. Radiography Shoulder Radiographs are the preferred initial study performed in the setting of traumatic shoulder pain. They can delineate shoulder malalignment and most shoulder fractures [4,5].


Shoulder Pain Traumatic PCAs

Shoulder Pain Traumatic PCAs. A standard set of shoulder radiographs for trauma should include at least three views: anterior-posterior (AP) views in internal and external rotation and an axillary or scapula-Y view. Axillary or scapula-Y views are vital in evaluating traumatic shoulder injuries as acromioclavicular and glenohumeral dislocations can be misclassified on AP views [6,7]. Radiographs provide good delineation of bony anatomy to assess for fracture and appropriate shoulder alignment, which are the two primary concerns in management of acute traumatic shoulder pain. Radiographs should also be performed upright since malalignment of the shoulder can be under-represented on supine radiographs [4]. Additional views, such as the Bernageau view, have been shown to be effective in demonstrating the degree of bone loss of the glenoid or humeral head [8]. CT Shoulder Computed tomography (CT) is better able than radiographs to characterize fracture patterns [9-11]. However, radiographs are preferred over CT for initial evaluation because radiographs are able to diagnose displaced 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 fractures and shoulder malalignment, which are the primary concerns in the initial assessment of shoulder trauma. CT is considered inferior to MRI for diagnosing essentially all soft-tissue shoulder injuries. CT Arthrography Shoulder CT arthrogram, although not the initial study of choice, has the advantage of characterizing both bony lesions and significant soft-tissue injuries.


Shoulder Pain Traumatic PCAs

Shoulder Pain Traumatic PCAs. CT arthrograms have been shown to be comparable to magnetic resonance (MR) arthrography in diagnosing Bankart, Hill-Sachs, superior labral anterior-to-posterior (SLAP), and full-thickness rotator cuff tears, but inferior to MR arthrography for diagnosing partial-thickness rotator cuff tears [12], including bursal-sided tears. CT arthrography has also only demonstrated modest agreement between observers in diagnosing anterior capsular laxity of the shoulder [13]. MRI Shoulder Noncontrast MR imaging (MRI) has been shown to be effective in assessing bony morphology and bone loss in patients with traumatic shoulder injuries [14-18], and noncontrast MRI is effective in diagnosing most traumatic soft-tissue pathologies including labral, rotator cuff, and glenohumeral ligament injuries [17,19,20]. MR Arthrography Shoulder MR arthrography is considered the gold standard for imaging traumatic shoulder pain [4,17,19,21]. MR arthrography is comparable to noncontrast MRI in assessment of extra-articular soft tissues, and MR arthrography has been shown to be superior to noncontrast MRI in diagnosing intra-articular pathology like SLAP tears, labroligamentous injuries, and partial rotator cuff tears [17,19]. MR arthrography is comparable to CT in evaluating traumatic osseous lesions, such as bony Bankart and Hill-Sachs lesions [12,18]. However, the need for an invasive procedure makes MR arthrography a suboptimal initial study. US Shoulder Ultrasound (US) has limited usefulness in patients with traumatic shoulder pain that cannot be localized to the rotator cuff or biceps tendon. US is comparable to MRI in evaluating full-thickness rotator cuff tears and rotator cuff atrophy [17,22,23]. However, US is inferior to MRI in evaluating partial-thickness rotator cuff tears and other intra-articular pathology [17,24].


Shoulder Pain Traumatic PCAs

Shoulder Pain Traumatic PCAs. Diagnosis of proximal humerus fractures by US has been described [25], but US is not generally considered a preferred imaging modality for assessing osseous pathology, which are of primary concern in initial assessment of traumatic shoulder pain. FDG-PET/CT Skull Base to Mid-Thigh Positron emission tomography (PET) (usually using the fluorine-18-2-fluoro-2-deoxy-D-glucose [FDG] tracer) imaging is rarely used in assessment of traumatic shoulder pain. FDG-PET is sensitive for inflammation, and a correlation has been found between radiotracer activity and degree of shoulder pain [26]. However, increased radiotracer activity may be due to infectious, traumatic, inflammatory, or neoplastic processes, making this activity a nonspecific finding. FDG-PET imaging as an isolated modality has relatively poor resolution for pathology localization compared with other imaging modalities; however, FDG-PET imaging can be performed in conjunction with MRI or CT for better localization of radiotracer activity. FDG-PET in combination with CT (FDG-PET/CT) is sensitive for identifying fractures, and it has been shown to be reliable in differentiating benign from malignant pathologic fractures [27]. FDG-PET/CT imaging is not routinely performed for characterization of soft-tissue injuries of the shoulder. Indirect identification of symptomatic rotator cuff tears has been described on FDG-PET/CT by decreased radiotracer activity in the muscles of the torn tendons and increased activity of surrounding shoulder girdle muscles due to muscle recruitment [28,29]. Other soft-tissue injuries, such as labral and cartilage injuries, have not been described using FDG-PET/CT. Bone Scan Shoulder Tc-99m bone scintigraphy is rarely used in the assessment of traumatic shoulder pain. Bone scintigraphy demonstrates increased activity in many post-traumatic shoulder pathologies, such as fracture, rotator cuff tear, or adhesive capsulitis [30].


Shoulder Pain Traumatic PCAs

Shoulder Pain Traumatic PCAs. Bone scintigraphy as an isolated modality has relatively poor resolution for pathology localization compared with other imaging modalities; however, bone scintigraphy can be performed in conjunction with MRI or CT for better localization of radiotracer activity. Bone scintigraphy has sensitivity and specificity comparable to MRI in diagnosis of occult bone fractures, and it can be used to identify other foci of bone involvement in pathologic fractures due to metastatic disease [31,32]. Increased radiotracer activity has been associated with symptomatic rotator cuff tears, but bone scintigraphy appearance of other soft-tissue injuries of the shoulder have not been well described [33]. Variant 2: Traumatic shoulder pain. Nonlocalized shoulder pain. Negative radiographs. Next imaging study. Appropriately positioned radiographs can exclude shoulder dislocation and most displaced fractures as the etiology for post-traumatic shoulder pain. In the setting of normal shoulder radiographs, the most common causes of post-traumatic shoulder pain are soft-tissue injuries such as rotator cuff and labral tears. MRI Shoulder Noncontrast MRI is a reasonable imaging study in the setting of acute nonlocalized traumatic shoulder pain and noncontributory radiographs. In the acute trauma setting, noncontrast MRI may be preferred to MR arthrography, as acute intra-articular pathology will typically produce significant joint effusion for assessment of intra-articular soft-tissue structures. MRI is the preferred imaging modality in assessing extra-articular soft-tissue traumatic pathology such as capsular and ligament tears [34,35]. MRI is also sensitive for diagnosing bone marrow contusion and has been shown to be beneficial in assessing shoulder physeal injuries in pediatric patients [36,37]. MR Arthrography Shoulder MR arthrography has been found to be superior to noncontrast MRI in the diagnosis of labroligamentous and partial-thickness rotator cuff tears [17,19].


Shoulder Pain Traumatic PCAs

Shoulder Pain Traumatic PCAs. In the acute trauma setting, however, noncontrast MRI may be preferred to MR arthrography because acute intra-articular pathology will typically produce significant joint effusion for assessment of intra-articular soft-tissue structures. MRI is the preferred imaging modality in assessing extra-articular soft-tissue traumatic pathology such as capsular and ligament tears [34,35]. MRI is also sensitive for diagnosing bone marrow contusion and has been shown to be beneficial in assessing shoulder physeal injuries in pediatric patients [36,37]. US Shoulder US has limited usefulness in patients with traumatic shoulder pain that cannot be localized to the rotator cuff or biceps tendon. In the post-traumatic setting, US has been shown to detect abnormalities, including proximal humeral fractures [25]; however, recent studies on US performed for nonspecific shoulder pain have had conflicting results. US for persistent shoulder pain after trauma has been found to diagnose significant pathology, primarily fractures and rotator cuff tears, in 90% of patients [25]. However, 40% of patients presenting with nonspecific shoulder pain were found to have no significant pathology on US [38]. Additionally, US has been demonstrated to be inferior to MRI in assessment of labroligamentous, osseous, and rotator cuff pathology [17]. US can be considered as a screening tool in patients with persistent nonspecific shoulder pain after trauma, particularly in an older patient population in whom rotator cuff tears are more common. However, a low threshold should be maintained for performing additional imaging in the setting of a noncontributory shoulder US examination. CT Shoulder CT Shoulder CT has virtually no usefulness in diagnosing common traumatic soft-tissue injuries such as rotator cuff tears, labroligamentous injuries, and muscle tears.


Shoulder Pain Traumatic PCAs

Shoulder Pain Traumatic PCAs. Although CT is the gold standard for diagnosing and characterizing fractures, MRI has been shown to be equivalent to CT in diagnosing the nondisplaced fractures that are typically missed on radiographs. CT Arthrography Shoulder CT is inferior to MRI and US in diagnosing virtually all extra-articular traumatic soft-tissues injuries. CT is considered the gold standard in identifying fractures. However, MRI has shown to be equivalent to CT in assessing bone loss [12,18], and MRI is usually adequate for diagnosing the nondisplaced fractures that are typically missed on conventional radiographs. CT arthrography is able to reliably evaluate for glenohumeral cartilage injury, SLAP tears, and labroligamentous injuries [12,39] but is generally considered inferior to MRI in diagnosing rotator cuff and soft-tissue Bankart lesions [12]. FDG-PET/CT Skull Base to Mid-Thigh FDG-PET/CT Skull Base to Mid-Thigh FDG-PET/CT imaging is rarely used in assessment of traumatic shoulder pain. FDG-PET is sensitive for inflammation, and a correlation has been found between radiotracer activity and degree of shoulder pain [26]. However, increased radiotracer activity may be due to infectious, traumatic, inflammatory, or neoplastic processes, making this activity a nonspecific finding. FDG-PET imaging as an isolated modality has relatively poor resolution for pathology localization compared with other imaging modalities, although, FDG-PET imaging can be performed in conjunction with MRI or CT for better localization of radiotracer activity. FDG-PET in combination with CT is sensitive for identifying fractures, and it has been shown to be reliable in differentiating benign from malignant pathologic fractures [27]. FDG-PET/CT imaging is not routinely performed for characterization of soft-tissue injuries of the shoulder.


Shoulder Pain Traumatic PCAs

Shoulder Pain Traumatic PCAs. Indirect identification of symptomatic rotator cuff tears has been described on FDG-PET/CT by decreased radiotracer activity in the muscles of the torn tendons and increased activity of surrounding shoulder girdle muscles due to muscle recruitment [28,29]. Other soft-tissue injuries, such as labral and cartilage injuries, have not been described using FDG-PET/CT. Bone Scan Shoulder Tc-99m bone scintigraphy is rarely used in assessment of traumatic shoulder pain. Bone scintigraphy demonstrates increased activity in many post-traumatic shoulder pathologies such as fracture, rotator cuff tear, or adhesive capsulitis [30]. Bone scintigraphy as an isolated modality has relatively poor resolution for pathology localization compared with other imaging modalities; however, bone scintigraphy can be performed in conjunction with MRI or CT for better localization of radiotracer activity. Bone scintigraphy has sensitivity and specificity comparable to MRI in diagnosis of occult bone fractures, and bone scintigraphy can be used to identify other foci of bone involvement in pathologic fractures due to metastatic disease [31,32]. Increased radiotracer activity has been associated with symptomatic rotator cuff tears, but bone scintigraphy appearance of other soft- tissue injuries of the shoulder have not been well described [33]. Variant 3: Traumatic shoulder pain. Radiographs show humeral head or neck fracture. Next imaging study. Proximal humerus fractures of the head and neck are relatively common. These fractures have a bimodal age distribution, occurring in young patients as the result of high-energy trauma and older patients with low-energy trauma, such as falls from a standing position. The most commonly used classification for humeral head fractures is the Neer classification system. A complete tear of at least one rotator cuff tendon can be seen in up to 40% of humeral head fractures [40].


Shoulder Pain Traumatic PCAs

Shoulder Pain Traumatic PCAs. However, a delay in repair of rotator cuff tears by up to 4 months has not been shown to have adverse outcomes on rotator cuff repair [41], and immediate diagnosis and treatment of soft-tissue injury in the setting of a proximal humerus fracture may not be required. CT Shoulder Nondisplaced fracture planes and complex bony anatomy can result in underappreciation of the extent of proximal humeral fractures on radiographs. Poor agreement between observers has been shown on grading of humeral head fractures on radiographs [10]. CT is the best examination for delineating fracture patterns and has been shown to be equivocal to MRI in identifying nondisplaced fractures, making it the preferred study for characterizing proximal humeral fractures. Contrast is generally not necessary unless there is concern for arterial injury (see Variant 9). 3-D volume-rendered CT images may be obtained to better characterize fracture patterns and humeral neck angulation, which can affect functional outcomes [42]. CT Arthrography Shoulder CT Arthrography Shoulder Arthrography is not routinely performed in conjunction with CT in the evaluation of proximal humeral fractures. In the acute setting, glenohumeral hemarthrosis can obscure soft-tissue structures typically evaluated on CT arthrography, and intra-articular iodinated contrast can obscure intra-articular humerus fracture planes. Because of the high association between humeral head fractures and rotator cuff tears, there may be a role for CT arthrogram in a patient with remote proximal humeral fracture having a suspected rotator cuff tear and contraindication to MRI. MRI Shoulder MRI Shoulder MRI without contrast is inferior to CT in evaluating fracture planes in complex humerus fracture patterns and is, in general, inferior to CT in characterizing proximal humerus fractures.


Shoulder Pain Traumatic PCAs

Shoulder Pain Traumatic PCAs. Although MRI can detect rotator cuff tears associated with proximal humeral fracture [43], any significant rotator cuff tear associated with the humeral head fracture is typically addressed during open reduction and internal fixation of the fracture. However, noncontrast MRI may be useful in assessing rotator cuff integrity in patients with proximal humeral fractures that do not undergo surgical fixation. MR Arthrography Shoulder MR arthrography is not indicated in the acute setting of proximal humeral fractures. In the acute setting of proximal humeral fracture, a significant hemarthrosis is typically present, allowing for adequate distention of the glenohumeral joint for identification of intra-articular pathology on noncontrast MRI. MR arthrography is generally preferred over noncontrast MRI for evaluating soft-tissue injuries in patients with remote proximal humeral fracture and persistent pain [17,19]. FDG-PET/CT Skull Base to Mid-Thigh FDG-PET in combination with CT has been shown to be reliable in differentiating benign from malignant pathologic fractures [27]. FDG-PET/CT can be used to further assess suspected pathologic fractures of the proximal humerus. Bone Scan Shoulder Bone scintigraphy has sensitivity and specificity comparable to MRI in diagnosis of occult bone fractures, and bone scintigraphy can be used to identify other foci of bone involvement in pathologic fractures due to metastatic disease [31,32]. Bone scintigraphy can be used to characterize proximal humerus fractures suspected to be due to metastatic disease. Variant 4: Traumatic shoulder pain. Radiographs show scapula fracture. Next imaging study. There is no consensus on indications for surgical fixation of scapula fractures. In general, isolated scapula body fractures heal well without surgical fixation, although associated rib fractures or higher injury severity score are associated with worse clinical outcomes and may benefit from more aggressive surgical fixation [45].


Shoulder Pain Traumatic PCAs

Shoulder Pain Traumatic PCAs. Scapula fractures involving the glenoid articular surface or glenoid neck may also require surgical fixation. CT Arthrography Shoulder CT Arthrography Shoulder CT arthrography is not routinely performed in the setting of scapula fractures. Intra-articular iodinated contrast can obscure intra-articular fracture lines involving the glenoid neck and articular surface. Acute intra-articular fractures are typically associated with significant hemarthrosis, which can limit evaluation of soft-tissue structures on CT arthrography. MRI Shoulder MRI has limited usefulness in assessing scapular fractures. The thin cortex and sparse medullary cavity of the scapula body can make diagnosis of scapula body fractures difficult on MRI [49]. Typical shoulder-specific coils used for MRI are also unable to cover the entire scapula, requiring use of body coils with a larger field of view, which then results in suboptimal resolution for evaluation of scapular fracture displacement and angulation. MR Arthrography Shoulder There is no role for an MR arthrogram in evaluation of scapula fractures. US Shoulder US Shoulder There is no role for US in evaluation of scapula fractures. FDG-PET/CT Skull Base to Mid-Thigh FDG-PET/CT has been shown to be reliable in differentiating benign from malignant pathologic fractures [27]. FDG-PET/CT can be used to further assess suspected pathologic fractures of the scapula. Bone Scan Shoulder Bone Scan Shoulder Bone scintigraphy has sensitivity and specificity comparable to MRI in diagnosis of occult bone fractures, and bone scintigraphy can be used to identify other foci of bone involvement in pathologic fractures due to metastatic disease [31,32]. Bone scintigraphy can be used to characterize scapula fractures suspected to be due to metastatic disease. MRI Shoulder Similar to MR arthrography, noncontrast MRI is comparable to CT in evaluating glenoid and humeral head bone loss [12,18]. In general, noncontrast MRI performs well in diagnosing labroligamentous injuries [20,52].


Shoulder Pain Traumatic PCAs

Shoulder Pain Traumatic PCAs. However, noncontrast MRI is considered inferior to MR arthrography for assessing labroligamentous pathology frequently associated with Bankart and Hill-Sachs lesions [17,19]. Noncontrast MRI is a good alternative to MR arthrography in the setting of acute injury when significant glenohumeral joint effusion is present to assist in visualization of intra-articular soft-tissue pathology. MR Arthrography Shoulder MR arthrography is the preferred study for evaluating subacute or chronic Bankart lesions because of its soft- tissue contrast. Multiple studies have shown MR arthrography to be reliable in diagnosing labroligamentous injuries [12,17,52] and superior to noncontrast MRI for this indication [17,19]. MR arthrography has been shown to be equivalent to CT in the assessment of glenoid and humeral head bone loss [12,18], while being superior to CT in assessment of labroligamentous injuries [12]. MR arthrography is also able to delineate humeral head and glenoid cartilage, which can be important because some Hill-Sachs lesions affect cartilage only [11]. CT Shoulder Noncontrast CT has historically been used to assess Hill-Sachs and bony Bankart lesions. However, MRI has been shown to be equivalent to CT for assessing both glenoid and humeral head bone loss [12,18,53], and CT is limited in the assessment of cartilaginous Hill-Sachs lesions [11]. In addition, CT cannot assess injury to soft-tissue structures like the labroligamentous complex, which further limits its usefulness in evaluating Bankart lesions. CT should be reserved for patients with a contraindication to MRI or patients in whom MRI assessment of bone loss is limited. CT Arthrography Shoulder CT Arthrography Shoulder CT arthrography has shown fair agreement between observers and is comparable to MR arthrography in diagnosing Bankart and Hill-Sachs lesions [12,13]. However, CT arthrography is inferior to MRI in diagnosing other soft-tissue pathology [12].


Shoulder Pain Traumatic PCAs

Shoulder Pain Traumatic PCAs. CT arthrography can be considered a reasonable imaging alternative in patients with contraindication to MRI. US Shoulder US Shoulder There is no role for US in assessment of Bankart or Hill-Sachs lesions. US has been demonstrated to be inferior to MRI in diagnosing both labroligamentous injury and Hill-Sachs lesions [17]. FDG-PET/CT Skull Base to Mid-Thigh There is no role for FDG-PET/CT in assessment of Bankart or Hill-Sachs lesions. Bone Scan Shoulder Bone Scan Shoulder There is no role for bone scintigraphy in assessment of Bankart or Hill-Sachs lesions. Variant 6: Traumatic shoulder pain. Radiographs normal. Physical examination and history consistent with dislocation event or instability. Next imaging study. Shoulder dislocation or instability is most common in the anterior direction. Younger patients are more likely to have labroligamentous injury and persistent instability after dislocation compared with older patients [54]. Older patients are more likely to have rotator cuff tears in association with shoulder dislocation [55]. Coexisting humeral avulsion of the glenohumeral ligament and significant glenoid bone loss have been found in up to 10% of patients with recurrent shoulder instability [56], which underscores the need to assess both osseous and labroligamentous pathology in patients with shoulder dislocation or instability. Glenoid morphology and bone loss can play a significant factor in recurrent shoulder dislocations [15,16,57], which may require bone grafting in order to restore stability [57]. MR Arthrography Shoulder MR arthrography is the preferred examination for the evaluation of subacute shoulder dislocations or recurrent shoulder instability. MRI has been shown to have similar performance to CT in the evaluation of Hill-Sachs lesions and glenoid bone loss [12,18]. MR arthrography has also been found to be reliable in diagnosing anterior shoulder instability and labroligamentous injuries [58,59].


Shoulder Pain Traumatic PCAs

Shoulder Pain Traumatic PCAs. MR arthrography has specifically outperformed noncontrast MRI in assessment of glenohumeral ligament and anterior labral injuries [17,19], which are commonly seen in shoulder instability. MR arthrography has also outperformed noncontrast MRI in diagnosis of rotator cuff tears [17,19], which is a common associated finding in older patients with shoulder dislocation. However, high sensitivities reported for MR arthrography in the detection of labral pathology may not be applicable to patients with clinically unstable shoulders. A retrospective review of 90 patients with clinically unstable shoulders selected for arthroscopy [60] found that MR arthrography had a sensitivity of 65% for detection of labral tears. The authors proposed that this discrepancy with prior studies was the result of different patient selection criteria (clinically unstable in their study versus less-specific symptoms such as shoulder pain in others) and the interpretation of MR arthrography by experienced musculoskeletal radiologists [60]. For this document, it is assumed the procedure is performed and interpreted by an expert. MRI Shoulder MRI without contrast may be preferred to MR arthrography in the setting of acute shoulder dislocation when a post-traumatic joint effusion is present to provide sufficient visualization of soft-tissue structures. In the subacute or chronic setting, the glenohumeral joint effusion is usually too small to provide adequate joint distention for optimal assessment of soft-tissue structures. Noncontrast MRI has been shown to be inferior to MR arthrography in diagnosing labroligamentous and rotator cuff injuries [17,19]. Noncontrast MRI performs comparably to CT in evaluating glenoid and humeral head bone loss [12,18], which may obviate the need for noncontrast CT. CT Arthrography Shoulder CT Arthrography Shoulder CT arthrography is effective in evaluation of shoulder instability.


Shoulder Pain Traumatic PCAs

Shoulder Pain Traumatic PCAs. CT arthrography is comparable to MR arthrography in the diagnosis of Bankart and Hill-Sachs lesions [12], and moderate agreement has been found between readers for diagnosing anterior capsule laxity on CT arthrography. However, CT arthrography has been shown to be inferior to MR arthrography in assessing partial-thickness rotator cuff tears [12], which makes CT arthrography less desirable in older patients with dislocation/instability where rotator cuff tears are common. CT arthrography may be considered in a patient with shoulder dislocation/instability and contraindication to MRI. CT Shoulder Noncontrast CT has historically been performed to assess bone loss in patients with recurrent dislocation or chronic instability. However, recent studies have shown MRI to be equivalent to CT in assessment of glenoid and humeral head bone loss [12,18], which places in question the need for noncontrast CT in the assessment of shoulder instability. Noncontrast CT is also unable to assess rotator cuff and labroligamentous pathology commonly seen in shoulder dislocations/instability. In general, CT should be reserved for patients with a contraindication to MRI or patients in whom MRI assessment of bone loss is limited. US Shoulder There is no defined role for US in the assessment of shoulder dislocation or instability. There is a potential limited role for use of dynamic US in assessing Hill-Sachs lesion engagement [61]. However, this is not common practice, and US has been shown to be inferior to MRI in diagnosing the common structural abnormalities associated with shoulder instability, such as labroligamentous injuries, Hill-Sachs lesions, and partial rotator cuff tears [17]. FDG-PET/CT Skull Base to Mid-Thigh There is no role for FDG-PET/CT in assessment of shoulder instability. Bone Scan Shoulder Bone Scan Shoulder There is no role for bone scintigraphy in assessment of shoulder instability. Variant 7: Traumatic shoulder pain. Radiographs normal.


Shoulder Pain Traumatic PCAs

Shoulder Pain Traumatic PCAs. Physical examination findings consistent with labral tear. Next imaging study. MR Arthrography Shoulder MR arthrography has been reported to have a high sensitivity for detection of labral injury, ranging from 86% to 100% [20,59,62-65]; however, the issue of selection bias is inherent in the design of many of these retrospective MRI Shoulder MRI without contrast may be preferred to MR arthrography in the setting of acute shoulder dislocation when a post-traumatic joint effusion is typically present to provide sufficient visualization of soft-tissue structures. In the subacute or chronic setting, the glenohumeral joint effusion is usually too small to provide adequate joint distention to adequately assess soft-tissue structures. Noncontrast MRI has been shown to be inferior to MR arthrography in diagnosing labroligamentous and rotator cuff injuries [17,19]. CT Arthrography Shoulder CT arthrography provides comparable sensitivity and possibly improved specificity in detection of labral lesions compared to MR arthrography [12,67] and can provide improved visualization of the bones in cases of complex trauma. However, interobserver variability in reporting of labral lesions is low [13]. CT arthrography has also been shown to be inferior to MR arthrography in assessing partial-thickness rotator cuff tears [12], which makes CT arthrography less desirable in patients where rotator cuff tears may be suspected. However, CT arthrography may be considered in a patient with shoulder dislocation/instability and contraindication to MRI. CT Shoulder CT Shoulder Noncontrast CT is unable to assess rotator cuff and labroligamentous pathology. US Shoulder Although there have been efforts to use US in diagnosis of labral lesions, it currently has no defined role in this setting. FDG-PET/CT Skull Base to Mid-Thigh There is no role for FDG-PET/CT in assessment of suspected labral tear. Bone Scan Shoulder There is no role for bone scintigraphy in assessment of suspected labral tear.


Shoulder Pain Traumatic PCAs

Shoulder Pain Traumatic PCAs. Variant 8: Traumatic shoulder pain. Radiographs normal. Physical examination findings consistent with rotator cuff tear. Next imaging study. US, MRI, and MR arthrography have similarly high sensitivity and specificity in detection of full-thickness rotator cuff tears. US and MRI have somewhat lower sensitivity for detection of partial-thickness tears when compared to MR arthrography [68]. However, because full-thickness tears are the main decision point on pursuing surgical repair, institutional preference may be the driving force for the selection of imaging modality for assessment of traumatic rotator cuff pathology. MRI Shoulder MRI Shoulder MRI is generally considered the best modality for adequately assessing most soft-tissue injuries, including labroligamentous, cartilage, and rotator cuff pathology [12,17,69]. It has high sensitivity and specificity in detection of full-thickness rotator cuff tears, but lower sensitivity compared to MR arthrography for detection of partial-thickness tears [68]. MR Arthrography Shoulder MR arthrography is generally preferred to noncontrast MRI for assessing intra-articular pathology, particularly in diagnosing labral and partial-thickness rotator cuff tears [17,19,54]. MR arthrography may have increased sensitivity for detection of partial-thickness articular surface supraspinatus tears compared with conventional MRI [19]. CT Arthrography Shoulder CT Arthrography Shoulder CT arthrography has similar performance as MR arthrography for detection of full-thickness rotator cuff tears, but has significantly poorer performance for partial-thickness cuff tears [12]. CT arthrogram may be a good imaging alternative in patients with suspected intra-articular soft-tissue injury and contraindication to MRI. US Shoulder In the post-traumatic setting, US has been shown to detect abnormalities, including rotator cuff tears [25]. In general, US can have high sensitivity and specificity for the detection of full-thickness rotator cuff tears [70-72].


Shoulder Pain Traumatic PCAs

Shoulder Pain Traumatic PCAs. There is conflicting evidence on the ability of US to diagnose partial-thickness rotator cuff tears [17,22,24,44,72]. Similarly, although interobserver agreement in detection of full-thickness rotator cuff tears can be high, it is much more variable for detection of partial-thickness tears [73,74]. FDG-PET/CT Skull Base to Mid-Thigh FDG-PET/CT is not routinely used for describing rotator cuff tears. Indirect identification of symptomatic rotator cuff tears has been described on FDG-PET/CT by decreased radiotracer activity in the muscles of the torn tendons and increased activity of surrounding shoulder girdle muscles due to muscle recruitment [28,29]. However, FDG- PET/CT cannot describe the extent of rotator cuff tear or degree of rotator cuff atrophy, which are relevant for clinical management. Bone Scan Shoulder Bone scintigraphy is not routinely used for describing rotator cuff tears. Increased radiotracer activity has been associated with symptomatic rotator cuff tears [33]. However, bone scintigraphy cannot describe the extent of rotator cuff tear or degree of rotator cuff atrophy, which are relevant for clinical management. Variant 9: Traumatic shoulder pain. Radiographs already performed. Physical examination consistent with vascular compromise. Next imaging study. The subclavian, axillary, and brachial arteries are uncommonly injured following fractures and dislocations about the shoulder; however, the consequences can be debilitating. Of these, the axillary artery is more likely to be injured in patients with proximal humeral fractures, and the risk increases in the presence of open fractures, shoulder dislocation, and fractures of the scapula and ribs [75]. No systematic or comparative data is available on detection of arterial injuries in the post-traumatic setting. CT Shoulder Noncontrast CT may be able to demonstrate hematomas; however, it is not an adequate modality for evaluation of acute arterial compromise.


Shoulder Pain Traumatic PCAs

Shoulder Pain Traumatic PCAs. Contrast-enhanced CT using intravenous (IV) contrast can identify some vascular injuries. However, contrast bolus timing and image reformatting using routine contrast-enhanced CT protocols is suboptimal for identifying and characterizing vascular injuries. CTA Shoulder CTA Shoulder CT angiography (CTA) is a specialized protocol for contrast-enhanced CT in which image acquisition occurs during maximum arterial opacification by IV contrast. Thin-slice axial images of the region of interest is performed, which helps in detection of subtle vascular injuries. Maximum intensity projection (MIP) images in multiple planes are also commonly performed, allowing for long segments of vessels to be visualized on a single image. CTA is the preferred examination for evaluation of suspected arterial injury. It can delineate the extent of injury and has the added benefit of providing optimal assessment of osseous injuries [76,77]. MRI Shoulder Because of the length of time required for MRI, it is not the modality of choice for assessment of acute arterial injury. Both routine noncontrast and contrast-enhanced MRI protocols lack the spatial and temporal resolution as well as imaging plane orientation to identify and characterize most arterial injuries. MRA Shoulder MRA Shoulder MR angiography (MRA) is MR imaging tailored to evaluate for arterial compromise using sequences such as time-of-flight, phase-contrast, and dynamic postcontrast imaging. MRA can produce 2D images or dynamic 3D images of the arteries that simulates arteriography. However, the special resolution of MRA is inferior to CTA and arteriography. MRA can be performed with or without IV contrast, although use of IV contrast is generally preferred. Because of the length of time required for MRA, it is not the modality of choice for assessment of acute arterial injury. US Duplex Doppler Shoulder Bedside US can be used to assess the subclavian, axillary, and brachial arteries as permitted by patient condition.


Shoulder Pain Traumatic PCAs

Shoulder Pain Traumatic PCAs. FDG-PET/CT Skull Base to Mid-Thigh There is no role for FDG-PET/CT in assessment of vascular compromise. 3-phase Bone Scan Shoulder Three-phase bone scintigraphy can demonstrate a lack of blood flow to an extremity, with blood pool and delayed images showing decreased or absent uptake in the affected area [78]. However, limited resolution precludes precise anatomic definition of the site of abnormality [78]. In addition, because of the length of time required for image acquisition, scintigraphy is not the modality of choice for assessing acute vascular compromise. CT Shoulder CT without contrast may be obtained in the setting of trauma for detection or delineation of fracture and can suggest neural injury based on expected course of the nerves. However, CT is not the modality of choice for assessment of the nerves. CT with contrast may be obtained in the setting of trauma for detection or delineation of arterial injury, and may suggest neural injury based on the expected course of the nerves. However, CT is not the modality of choice for assessment of the nerves. There is no role for biphasic CT in the setting of suspected traumatic nerve injury. CT Arthrography Shoulder There is no role for CT arthrography in the setting of suspected traumatic nerve injury. MRI Shoulder Noncontrast MRI may demonstrate discontinuity of nerves, neuromas, or perineural musculofascial edema; however, the imaging planes and resolution of routine noncontrast MRI is not adequate for confident and complete assessment of the nerves that can be injured at the shoulder [81]. There are no systematic studies on MR neurography in assessment of the peripheral nerves about the shoulder in the post-traumatic setting; however, MR neurography is gaining acceptance in assessment of peripheral nerve injuries [82]. Use of 3T imaging allows for high resolution and excellent soft-tissue contrast and can delineate focal nerve discontinuities, neuromas, and musculofascial edema [83].


Acutely Limping Child Up To Age 5 PCAs

Acutely Limping Child Up To Age 5 PCAs.  Introduction/Background Acute onset of limp or refusal to walk is a common complaint in children, accounting for approximately 4% of visits in one pediatric emergency department [1]. The acutely limping child can be a diagnostic dilemma for clinicians. Most commonly, the acute limp is caused by minor trauma or self-limiting benign conditions but can also be caused by limb-threatening or life-threatening etiologies [2-6]. The cause of limp can usually be determined by a careful history and physical examination. The differential diagnosis of limping is broad and depends on the presence of signs of infection, localization of pain, and history of trauma [6]. The differential diagnosis in a limping child also depends on age. This discussion relates to the initial imaging of the ambulatory child under the age of 5 years who presents with an acute onset of a limp. The presence of fever, elevated white blood cell count, elevated erythrocyte sedimentation rate, or elevated C- reactive protein suggests infection. Localization of pathology is based on site of pain, tenderness, presence of erythema, swelling, and positive physical maneuvers and signs, such as the Trendelenburg test, Galeazzi sign, Patrick/FABER test, pelvic compression test, and psoas sign [7]. A detailed analysis of gait can suggest the diagnosis [6]. Discussion of Procedures by Variant Variant 1: Child up to age 5. Acute limp. Nonlocalized symptoms. No concern for infection. Initial imaging. The most common noninfectious etiology of acute limping in children is a minor traumatic injury [8]. Unfortunately, particularly in younger children, it is common that the pain cannot be accurately localized to one focal area. When there is no concern for infection and pain cannot be localized through history or physical examination, an imaging strategy designed to first localize the source of the pain and subsequently better characterize the cause is typically pursued. Reprint requests to: publications@acr.org


Acutely Limping Child Up To Age 5 PCAs

Acutely Limping Child Up To Age 5 PCAs. Acutely Limping Child Up To Age 5 If initial imaging is normal but symptoms persist, follow-up radiographs or radiographs of areas besides the tibia/fibula may be useful. In the Baron et al study [13], approximately 10% of tibial fractures were only visible on follow-up radiographs and not initial imaging. One patient, who was discharged, later returned with worsening symptoms and signs of infection and was found to have spinal discitis and epidural abscess. As these examples illustrate, if the initial evaluation is negative and symptoms persist or worsen, a follow-up clinical reassessment and further imaging evaluation may be necessary. US Hips or Lower Extremity There is no relevant literature regarding the use of ultrasound (US) in the initial evaluation of acute limp with nonlocalized symptoms and no concern for infection. US is sensitive in evaluation of joint effusions and soft-tissue fluid collections; however, the typical field of view is small, limiting the role of US when symptoms and clinical evaluation cannot localize the site of pathology [14]. Because pain that is due to hip pathology can be referred elsewhere in the lower extremity, such as the thigh, knee, or buttock [15], US of the hip could be considered if initial radiographs are negative and symptoms persist. 3-Phase Bone Scan Pelvis and Lower Extremity There is no relevant literature regarding the use of bone scan in the initial evaluation of acute limp with nonlocalized symptoms and no concern for infection. Scintigraphic bone scan is sensitive in detecting bone pathology and could have a role in localizing the pathology in limping children when the examination is nonfocal, radiographs are negative, and symptoms persist [1,10,16,17]. However, a bone scan lacks specificity in this clinical scenario [1,10,16]. CT Lower Extremity There is no relevant literature regarding the use of CT in the initial evaluation of acute limp with nonlocalized symptoms and no concern for infection.


Acutely Limping Child Up To Age 5 PCAs

Acutely Limping Child Up To Age 5 PCAs. CT without intravenous (IV) contrast can be useful in a few selected cases for preoperative planning after radiographs demonstrate a complex fracture [18]. MRI Lower Extremity There is no relevant literature regarding the use of MRI pelvis/hips to feet in the initial evaluation of acute limp with nonlocalized symptoms and no concern for infection. MRI is sensitive and specific for soft-tissue, cartilage, and bony pathology, including detection of stress reaction/fractures [19]. It may be performed in selected children when radiographs, clinical and imaging follow- up, and thorough physical examination fail to provide diagnostic clues about the source of symptoms. MRI Whole-Body There is no relevant literature regarding the use of whole-body MRI in the initial evaluation of acute limp with nonlocalized symptoms and no concern for infection. Because whole-body MRI is sensitive and specific for soft-tissue, joint, and bony pathology, and it allows for coverage of all musculoskeletal anatomy, it could play a role in localizing pathology in the limping child when the examination is nonfocal, the initial imaging workup is negative, and symptoms persist. Whole-body MRI has been shown to have more superior sensitivity than scintigraphic bone scans or radiography in detection of multifocal neoplastic lesions and chronic nonbacterial osteomyelitis/chronic recurrent multifocal osteomyelitis [20-22]. Whole-body MRI may be sensitive for detecting sites of involvement with inflammatory arthritides or osteonecrosis [23-25]. Variant 2: Child up to age 5. Acute limp. Pain. Localized symptoms. No concern for infection. Initial imaging. The body regions covered in this clinical scenario are: hip, femur, knee, tibia/fibula, ankle, and foot. Localized pain may be due to trauma, in which case it is important to exclude an underlying fracture. Clinical examination and history may allow localization of the pain or injury to a specific area, which allows a more focused imaging evaluation [26].


Acutely Limping Child Up To Age 5 PCAs

Acutely Limping Child Up To Age 5 PCAs. Radiography Lower Extremity Targeted radiographs of the areas of concern have a role in evaluating for possible fracture [12,26-29]. Negative radiographs do not completely exclude the possibility of a nondisplaced fracture. Dunbar et al [30] first described Acutely Limping Child Up To Age 5 Other causes of limp or pain, such as osteochondritis, apophysitis, osteonecrosis, or tumor, may be diagnosed with radiographs, though MRI has better sensitivity for such pathologies [31,32]. US Hips or Lower Extremity US has a limited field of view and has lower accuracy in detection of fractures as compared with radiographs. Weinberg et al [33] showed that clinician-performed US had a sensitivity and specificity of 73% and 92%, respectively, for the evaluation of fractures in children and young adults, with radiography or CT as the reference standard. 3-Phase Bone Scan Pelvis and Lower Extremity There is no relevant literature regarding the use of bone scan in the initial evaluation of acute limp with localized symptoms and no concern for infection. CT Lower Extremity There is no relevant literature regarding the use of CT in the initial evaluation of acute limp with localized symptoms and no concern for infection. CT without IV contrast can be useful in a few selected cases for preoperative planning after radiographs demonstrate a complex or intra-articular fracture [18]. MRI Lower Extremity There is no relevant literature regarding the use of MRI in the initial evaluation of acute limp with localized symptoms and no concern for infection. In children with persistent limp and negative radiographs, MRI is highly sensitive in detection of stress reaction/fractures [6]. When there are clinical signs of nonseptic arthritis, MRI is superior to both US and radiography in detecting inflammatory changes, early erosions, and cartilage thinning [34-37]. MRI should be performed when a tumor is suspected as it is sensitive for evaluation of bone marrow and soft-tissue extension [38].


Acutely Limping Child Up To Age 5 PCAs

Acutely Limping Child Up To Age 5 PCAs. Variant 3: Child up to age 5. Acute limp. Nonlocalized symptoms. Concern for infection. Initial imaging. Limping in the presence of one or more of the following clinical and laboratory signs should suggest the possibility of infection: fever, elevated white blood cell count, elevated erythrocyte sedimentation rate, or elevated C-reactive protein. The differential diagnoses in this scenario most commonly include septic arthritis, osteomyelitis, discitis, pyomyositis, Langerhans cell histiocytosis, and tumor (eg, leukemia, osteosarcoma, Ewing sarcoma, and metastatic disease). When there are signs and symptoms suggestive of an infectious process, imaging has a role in substantiating the diagnosis, localizing the site of infection, evaluating for complications that require surgical intervention, and excluding other pathologies that mimic infection. Radiography Lower Extremities Radiographs have low yield in detecting infection when symptoms and signs are not localized [39,40]. US Hips or Lower Extremity A small field of view limits the role of US when symptoms and clinical evaluation cannot localize the site of pathology [14]. Because pain that is due to hip pathology can be referred elsewhere in the lower extremity, such as the thigh, knee, or buttock [15], US of the hip could be considered even when symptoms cannot be well localized. 3-Phase Bone Scan Pelvis and Lower Extremity Bone scan is reported to have a high sensitivity for the diagnosis of osteomyelitis [17]. Advantages of bone scan in the evaluation of infection include whole-body imaging for site localization, with the main disadvantage being the lack of soft-tissue evaluation and anatomic detail, particularly for the detection of small abscesses [16]. Bone scan may be particularly helpful in cases with implanted hardware and postoperative patients already with Acutely Limping Child Up To Age 5 extensive edema and tissue alternations.


Acutely Limping Child Up To Age 5 PCAs

Acutely Limping Child Up To Age 5 PCAs. A few case series suggest that bone scan has a lower sensitivity in the detection of source of infection relative to MRI [39-41]. MRI Lower Extremity MRI, given its sensitivity to soft-tissue and bone marrow pathology, has high accuracy in diagnosing infection, including septic arthritis, osteomyelitis, pyomyositis, and discitis [42,43], and could be considered as the initial imaging study [44]. Large field-of-view coronal T1-weighted and fluid-sensitive sequences covering from the pelvis and hips to the ankles may be performed to identify any abnormality. Inclusion of the lower thoracic spine and lumbar spine should be considered if lower extremity or hip pathology is not found and symptoms persist, as some patients with discitis may not have localized symptoms to the back [45-48]. Once localized, additional MRI sequences with smaller fields of view can be performed for further characterization [49]. Contrast administration in the MRI evaluation of suspected soft-tissue or osseous infection does not increase sensitivity or specificity but may increase reader confidence and better delineate abscesses [50,51]. Contrast administration during MRI should be considered in specific cases to improve detection of an abscess when there is significant soft-tissue edema [50,51]. An exception to this may be infants, in whom infection of the epiphyses can be occult on unenhanced MRI sequences [52]. Given these considerations, the use of IV contrast may vary with institutional protocol. While no prospective study of MRI versus bone scan has been performed, there are retrospective studies suggesting superiority of MRI over bone scan in detecting the source of infection, with sensitivity of 99% to 100% for MRI compared to 53% to 71% for bone scan [39,40]. Because of low bone scan sensitivity for soft- tissue pathology, MRI is often obtained after a positive bone scan for further evaluation of soft-tissues, primarily to detect abscess formation that requires drainage [41].


Acutely Limping Child Up To Age 5 PCAs

Acutely Limping Child Up To Age 5 PCAs. MRI Whole-Body MRI, given its sensitivity to soft-tissue and bone marrow pathology, has high accuracy in diagnosing infection, including septic arthritis, osteomyelitis, pyomyositis, and discitis [42,43]. Like bone scan, whole-body MRI provides a total-body screen and is sensitive in detecting osseous abnormalities. As such, whole-body MRI may be an appropriate choice when there is suspicion for multifocal osteomyelitis [22,53,54]. While there is no single protocol for whole-body MRI, sequences may include the use of fluid-sensitive, T1-weighted, diffusion-weighted imaging, or chemical shift imaging, with or without the use of IV contrast [53,55]. CT Lower Extremity There is no relevant literature regarding the use of CT in the initial evaluation of acute limp with nonlocalized symptoms and concern for infection. Variant 4: Child up to age 5. Acute limp. Symptoms localized to the hip. Concern for infection. Initial imaging. If pain or physical examination appears localized to the hip, the diagnosis is septic arthritis until proven otherwise. Septic arthritis is the most common cause of acute severe monoarticular pain in children. It typically results from hematogenous and subsequent intra-articular spread of Staphylococcus aureus, with the hip being the most common site of involvement. In some cases, septic arthritis of the hip may be secondary to adjacent osteomyelitis [56]. Septic arthritis requires rapid diagnosis and intervention to prevent permanent damage to the joint [57]. In children with signs of infection and absence of a hip effusion, a diagnosis of pelvic osteomyelitis or pyomyositis should be considered [40]. Radiography Pelvis or Lumbar Spine There are limited data to support the use of radiographs in the initial evaluation of possible septic hip. The sensitivity and specificity of radiographs for the diagnosis of septic hip are low [58]. US Hips US of the hip allows quick and accurate diagnosis of a joint effusion and can be used to guide aspiration [59,60].


Acutely Limping Child Up To Age 5 PCAs

Acutely Limping Child Up To Age 5 PCAs. Various investigators have had differing results in differentiating septic arthritis from transient synovitis of the hip when using US in combination with laboratory and clinical data [57,61]. A false-negative US is uncommon and could occur when sonography is performed within 24 hours of onset of symptoms [62]. It is important to be aware that there may be other etiologies to a hip effusion, including fractures, osteonecrosis, and juvenile idiopathic arthritis. Acutely Limping Child Up To Age 5 3-Phase Bone Scan Pelvis and Lower Extremity Bone scan was found to have only 70% sensitivity, as compared to MRI, in a series of 33 patients in detecting source of infection in children presented with acute hip pain who did not have septic hip [40]. CT Pelvis CT has decreased sensitivity in the detection of bone marrow pathology and decreased soft-tissue contrast compared to MRI [63-65]. CT with IV contrast could be considered in children with contraindications to MRI [66]. MRI Pelvis MRI has high sensitivity and specificity for musculoskeletal infection, such as septic arthritis, osteomyelitis, and pyomyositis [67]. MRI detected osteomyelitis in about half of children with clinically suspected septic arthritis [56], and septic arthritis was found to be associated with osteomyelitis in MRI in about 70% of patients. Some also have soft-tissue abscesses [67]. For this reason, some advocate using MRI in the initial evaluation of suspected septic arthritis of the hips. In children with signs of infection and acute hip pain with no evidence of septic arthritis, MRI was shown to have better sensitivity than bone scan in detection of the source of infection [40,41]. In addition, osteomyelitis of the pelvis is commonly (28%) associated with soft-tissue abscesses [68], which are easily detected by MRI. Some advocate performing MRI of the pelvis even in children with known septic arthritis because of the possibility of associated osteomyelitis and soft-tissue abscess [69].


Acutely Limping Child Up To Age 5 PCAs

Acutely Limping Child Up To Age 5 PCAs. Findings of hip effusion associated with bone marrow edema or decreased enhancement of the femoral head should raise the possibility of septic arthritis [70,71]; although, definite diagnosis of septic arthritis requires joint aspiration and fluid analysis. Contrast administration in the MRI evaluation of suspected soft-tissue or osseous infection does not increase sensitivity or specificity but increases reader confidence and better delineates abscesses [50,51]. An exception to this may be in infants and younger children with an abundance of nonossified cartilage, in whom infection limited to the intrinsically hyperintense cartilaginous growth plate and epiphyses/apophyses can be occult on unenhanced MRI sequences. Given these considerations, the use of IV contrast may vary with institutional protocol. Variant 5: Child up to age 5. Acute limp. Symptoms localized to lower extremity (not pelvis or hips). Concern for infection. Initial imaging. The body regions covered in this clinical scenario are: femur, knee, tibia/fibula, ankle, and foot. Radiography Lower Extremity There are limited evidence to support the use of radiographs for the acute evaluation of localized infection. The sensitivity of radiographs in detecting early osteomyelitis or soft-tissue infection is low [39,40]. While soft-tissue signs of swelling and edema may be detected early by radiographs and nonspecific signs, such as periosteal reaction and osteopenia, detection of bone destruction may take up to 3 weeks after onset of symptoms [54,64,72]. US Lower Extremity US may play a role in diagnosing pyomyositis, in which inflammatory change may lead to an altered sonographic appearance in affected muscle [73,74]. Because US will not penetrate cortex, it is unable to evaluate bone marrow and is not sensitive for osteomyelitis. US is sensitive to subperiosteal collections, which can be seen with osteomyelitis [54,75].


Acutely Limping Child Up To Age 5 PCAs

Acutely Limping Child Up To Age 5 PCAs. 3-Phase Bone Scan Pelvis and Lower Extremity Bone scan has been reported to have a high sensitivity for the diagnosis of osteomyelitis, albeit with lower reported specificity. However, its utility is greatest when symptoms cannot be localized. The main limitation of bone scan with a localized examination is in the detection of soft-tissue abscess [39,41]. CT Lower Extremity CT has decreased sensitivity in the detection of bone marrow pathology and decreased soft-tissue contrast compared to MRI [63-65]. CT with IV contrast can be considered when soft-tissue infection is of concern or in children with contraindications to MRI [66]. Acutely Limping Child Up To Age 5 MRI Lower Extremity MRI, given its sensitivity to musculoskeletal injury and inflammation, has high accuracy in diagnosing infection, specifically osteomyelitis and pyomyositis [43,76]. Contrast administration improves detection of soft-tissue abscesses in selected patients with soft-tissue edema [50,51]. Because of low bone scan sensitivity for soft-tissue pathology, MRI may sometimes need to be obtained after a positive bone scan for further evaluation of soft- tissues pathology mainly to detect any abscess formation that requires drainage [41]. Contrast administration in the MRI evaluation of suspected soft-tissue or osseous infection does not increase sensitivity or specificity but may increase reader confidence and better delineate abscesses [50,51]. Contrast administration during MRI should be considered in specific cases to improve detection of small abscesses when there is significant soft-tissue edema [50,51]. The need for sedation in young patients undergoing MRI is a consideration. MRI Whole-Body There is no relevant literature regarding the use of whole-body MRI in the initial evaluation of acute limp with localized symptoms to the lower extremity and concern for infection. Whole-body MRI may be very sensitive for osteomyelitis.


Anorectal Disease

Anorectal Disease.  Introduction/Background Inflammatory and infectious disorders of the anorectum are commonly encountered in clinical practice, but their exact incidence is unknown. They encompass a variety of anorectal disorders in a diverse population of patients who may present to the emergency department, urgent care clinic, primary care physician, or subspecialty physician such as a gastroenterologist or colorectal surgeon. Patients with inflammatory and infectious disorders of the anorectum may come in need of medical attention with acute symptoms such as pain, tenesmus, discharge, bleeding, and/or findings of sepsis. Other patients may have chronic symptoms, or their complaints may relate to a prior surgical procedure or underlying disease. Depending upon the condition and presentation, a variety of imaging modalities may be used for the initial evaluation of an anorectal complaint. Imaging may also be helpful for planning the management of rectovaginal fistulas that are the consequence of obstetric trauma from childbirth, iatrogenic anorectal or rectovaginal fistulas that are caused by radiation or surgical complications, and fistulas that result from other forms of trauma. The initial imaging in 4 anorectal disease categories is covered in this document: suspected perianal disease (perianal fistula and abscess); suspected rectal fistula (rectovescicular or rectovaginal); suspected proctitis or pouchitis; and suspected complication after proctectomy, coloproctectomy, or colectomy with pouch or other anastomosis. Special Imaging Considerations Anorectal Fistulae and Malignancy Though the focus of this topic is on inflammatory and infectious disorders of the anorectum, it is important to recognize that inflammatory disease of the anorectum may be a complication of malignancy or associated with malignancy. For example, approximately 11% of colovesical and colovaginal fistulae are caused by malignancy [1].


Anorectal Disease

Anorectal Disease. Recently, carcinoma has been reported in association with anal fistulae in Crohn disease (CD), and carcinomas may rarely arise in chronic fistula in the anorectum [2,3]. Consequently, the concern for malignancy should be raised when the imaging findings of a soft mass, mass-like thickening of the wall of the anorectum, or malignant- appearing lymphadenopathy are present during evaluation of the anorectum for suspected benign inflammatory disease. OR aMedstar Georgetown University Hospital, Washington, District of Columbia. bCleveland Clinic, Cleveland, Ohio. cPanel Chair, University of Wisconsin Hospital & Clinics, Madison, Wisconsin. dPanel Vice-Chair, University of California San Diego, San Diego, California. eMayo Clinic, Rochester, Minnesota, American Gastroenterological Association. fBoston University Medical Center, Boston, Massachusetts. gMedstar Georgetown University Hospital, Washington, District of Columbia, Primary care physician. hH. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida. iVirginia Tech Carilion School of Medicine, Roanoke, Virginia. jMassachusetts General Hospital, Boston, Massachusetts. kOregon Health and Science University, Portland, Oregon. lDuke University Medical Center, Durham, North Carolina. mEmory University, Atlanta, Georgia. nUniversity of Alabama at Birmingham, Birmingham, Alabama. oUniversity of California San Diego, San Diego, California. pUniversity of California San Francisco, San Francisco, California. qCleveland Clinic Florida, Weston, Florida, American College of Surgeons. rSpecialty Chair, Virginia Commonwealth University Medical Center, Richmond, Virginia. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels. Participation by representatives from collaborating societies on the expert panel does not necessarily imply individual or society endorsement of the final document.


Anorectal Disease

Anorectal Disease. Reprint requests to: publications@acr.org Anorectal Disease Discussion of Procedures by Variant Variant 1: Suspected perianal disease. Abscess or fistula. Initial imaging. Anorectal abscesses result from infection of the intersphincteric anal glands. Obstruction of the draining duct may produce an intersphincteric abscess or the infection may rupture through the external sphincter to form an abscess in the ischiorectal or ischioanal spaces. Cephalad extension results in a high intramuscular or perirectal abscess, or a supralevator abscess if it extends above the levator muscles. Posterior extension may result in a horseshoe abscess in the intersphincteric plane or ischiorectal fossa [4]. Patients with anorectal abscess may present with pain that is typically throbbing, visible redness and swelling of the anus, and/or sepsis. On physical examination, there is often tenderness to palpation and an area of fluctuance. In some cases, the abscess may be occult on physical examination. The majority of anal fistulae (fistula-in-ano) arise from a preexisting abscess and as such are believed to represent a spectrum of the same disease. Clinically, patients with fistula-in-ano present with drainage of blood, pus, or fecal material from an external opening in the perianal region, intermittent pain, and perianal itching. The majority of patients with fistula-in-ano are male (2:1) and have a mean age at presentation of 40 years [5]. Other diseases that may cause anal fistula include CD, radiation proctitis, foreign body, prior anal surgery, infections (such as human immunodeficiency virus [HIV], tuberculosis, actinomycosis), and malignancy [6]. Perianal fistulae are a very common component of CD, occurring in 13% to 27% of these patients [7,8]. Perianal fistulae may be the initial manifestation of CD in up to 81% of patients who develop perianal disease, and in a small number of patients, it is the only manifestation of their disease [9]. Complex and multifocal fistulae are more common in CD.


Anorectal Disease

Anorectal Disease. Imaging is used in suspected cases of anorectal abscess and/or fistula to confirm the diagnosis, assist in surgical planning, predict surgical outcome, assess for recurrent or residual disease, and monitor medical therapy in patients with CD [10]. CT Pelvis The appropriate CT protocol for imaging a patient with an anorectal complaint depends upon the presentation and differential diagnosis. Intravenous (IV) contrast is preferred to a noncontrast examination to help visualize and characterize fluid collections, abscesses, and fistulous tracts. Water-soluble rectal contrast is generally not necessary to diagnose a rectal abscess and may be challenging to administer depending on symptom severity. However, rectal contrast may help delineate perforation or leak in a patient with a history of trauma or recent surgery. Water-soluble rectal contrast is preferred over barium to avoid the possibility of barium spilling into the peritoneal cavity or spaces of the extraperitoneal pelvis. Water-soluble rectal contrast is also preferred in a patient who could potentially be undergoing surgery. CT is commonly used in the acute setting to evaluate for anorectal abscess. The inherent lack of contrast resolution of CT limits the differentiation of subtle attenuation changes to differentiate small abscesses and fistulae from the anal sphincter complex and the soft tissue of the pelvic floor. To our knowledge, there is no recent literature evaluating the accuracy of modern CT technology for the detection of anorectal abscesses and there are no studies comparing IV contrast-enhanced scans to scans obtained without IV contrast. CT with and without IV contrast would only be useful when there is benefit from dual-phase imaging (eg, gastrointestinal bleeding). However, IV contrast is important to delineate rim-enhancement of fluid collections to aid in the diagnosis of abscess. The reported sensitivity of CT for anorectal abscess is 77% [11].


Anorectal Disease

Anorectal Disease. Comparing CT with endoanal ultrasound (US) and surgical findings, only 24% of perianal fistulae were correctly classified on CT, as compared with 82% by endoanal US in a small series of 25 patients reported by Schratter-Sehn et al [12]. Fluoroscopy Contrast Enema Fluoroscopic contrast enema is not useful in this clinical scenario because it cannot assess the presence or absence of an abscess or fistula tract. There is no relevant literature regarding the use of contrast enema in the evaluation of perianal disease. Fluoroscopy Fistulography Fluoroscopic fistulography is performed by cannulating the external opening of a fistula with a small-gauge catheter, such as an IV catheter, pediatric feeding tube, or lacrimal cannula. Scout radiographs are obtained prior to careful injection of water-soluble contrast material into the fistula tract while obtaining spot radiographs [13]. Care Anorectal Disease should be taken not to inadvertently obscure a distal fistula with the enema or catheter tip or the balloon of a catheter. Fistulography may also be performed with CT by injecting a dilute water-soluble contrast material into an external opening of a fistula; however, there is limited published experience with this technique [14,15]. Fluoroscopic fistulography is rarely performed for perianal disease and has been replaced by modern cross-sectional imaging in this setting. Data on the accuracy of fluoroscopic fistulography are available from small series reported in older medical literature. Weisman et al [13] reported the highest sensitivity (89%) for identification of the primary tract in a retrospective review of 27 patients. In contrast, Kuijpers and Schulpen [16] found fistulography was accurate in only 16% of patients in a retrospective review of 25 patients [16]. The limitations of fistulography include lack of filling of the entire tract or extensions of the tract because inflammatory debris in the tract may prevent contrast filling. In these cases, the internal opening may not be defined.


Anorectal Disease

Anorectal Disease. Furthermore, the anal sphincter complex and levator ani are not visualized fluoroscopically; as such, the relationship of the fistula to these structures cannot be defined. Pelvic MRI with a multichannel phased array body coil has become the standard for imaging perianal fistula, especially those associated with CD, because they are more frequently complex with clinically occult tracts. Imaging with a body coil is better tolerated and is not limited by the field of view compared with MRI with an endoanal coil. The surgical concordance with fistula detection has been shown to be better with a body coil (96%) compared with an endoanal coil (68%) [20]. In multiple studies, MRI has been shown to have high sensitivity and specificity for the evaluation of perianal fistula. The meta-analysis by Zbar and Armitage [21] showed MRI had a sensitivity ranging from 81% to 100% and specificity from 67% to 100%, with accuracy for identification of the internal opening of 74% to 97%, and delineation of horseshoe fistula of 97% to 100% [21]. Sahni et al [22] showed that, for diagnosis of the primary fistula in CD patients, MRI had an accuracy of 64% to 100%. Comparing MRI to examination under anesthesia with or without endoanal US, the sensitivity and specificity for discriminating complex from simple perianal fistula was 97% and 96%, 92% and 85% for MRI, and 75% and 64% for endoanal US. Though fistula can be readily identified on MRI without IV contrast as hyperintense tracts on FSE T2-weighted sequences and short-tau inversion recovery sequences, the use of IV contrast facilitates visualization because tracts with active inflammation will avidly enhance and small associated abscesses will show ring enhancement around a central fluid collection. IV contrast enables the differentiation of inactive tracts containing granulation tissue, which diffusely enhance from active tracts that have ring or rim-like enhancement [18].


Anorectal Disease

Anorectal Disease. Lo Re et al [23] retrospectively evaluated MRI in 31 patients with CD suspected of having perianal fistula and a surgical examination under anesthesia showing that short-tau inversion recovery sequences were equivalent to IV contrast-enhanced fat-suppressed T1-weighted sequences in detection and classification of anal fistula with sensitivity of 96%, specificity of 75%, positive predictive value (PPV) of 93%, and negative predictive value (NPV) of 86% for both sequences [23]. However, their study did not evaluate tract activity. In another retrospective study of 17 patients that underwent MRI prior to surgery, the contribution of MRI sequences to fistula classification was evaluated. All 3 readers showed statistically significant concordance between fistula classification and surgery with IV contrast-enhanced fat-suppressed T1-weighted sequences. The highest concordance for all 3 readers was reached Anorectal Disease with the combination of T2-weighted sequences and IV contrast-enhanced fat-suppressed T1-weighted sequences [24]. Finally, Dohan et al [19] evaluated the addition of diffusion imaging in a retrospective study of 24 patients with perianal fistula that went to surgery. The sensitivity for anal fistula detection for fat-suppressed FSE T2-weighted sequences was 91.2% and for diffusion imaging was 100%, with statistically significant greater fistula conspicuity on diffusion imaging than fat-suppressed FSE T2-weighted sequences. Radiography Pelvis Radiography is not useful in this clinical scenario because it cannot assess the presence or absence of an abscess or fistula tract. There is no relevant literature to support the use of radiography in the evaluation of perianal fistula. In a recent study of 122 patients by Sun et al [27], the reported sensitivity, specificity, and accuracy for the diagnosis of perianal fistula compared with surgery was 92%, 100%, and 93%, respectively. This study reported an accuracy of identification of the internal opening of the fistula of 95%.


Anorectal Disease

Anorectal Disease. In an earlier study of 104 patients by Buchanan et al [28], comparing endoanal US with MRI, endoanal US correctly classified 81% of perianal fistulae compared with 90% by MRI. Their accuracy for detection of the internal opening was 91% by endoanal US and 97% by MRI. Endoanal US is limited by the field of view and depth of penetration. Accuracy for identification of extrasphincteric and suprasphincteric tracts (50% and 67%, respectively) is lower compared with transsphincteric and intersphincteric tracts (93% and 88%, respectively) [27]. Other limitations include obscuration of the tract or secondary extensions by gas in the tract or gas in an associated abscess. In patients with recurrent disease, it may be impossible to distinguish tracts with active inflammation from those with fibrosis and granulation tissue, which is often a clinical question in patients with CD. Hydrogen peroxide may be injected into the external opening of the fistula during endoanal US to enhance visualization of fistula tracts [29]. A tract filled with hydrogen peroxide is brightly hyperechoic on endoanal US, improving its visualization and connection to abscess cavities as well as differentiating it from scar tissue [25]. Variant 2: Suspected rectal fistula. Rectovesicular or rectovaginal. Initial imaging. Rectovaginal and rectovesicular fistulae are uncommon. The most common cause of a rectovaginal fistula is obstetric or vaginal trauma (88% of cases) [32], followed by CD, which accounts for approximately 9% of cases [33]. Other causes include radiation; pelvic infections (diverticulitis, tuberculosis, lymphogranuloma venereum, human papilloma virus, HIV, cytomegalovirus, and schistosomiasis); malignancies of the anorectum, perineum, and gynecologic organs; and iatrogenic injury and postoperative complications. Upon initial imaging, the organ of origin may be unknown. Rectovaginal fistulae are subclassified as high or low fistulae.


Anorectal Disease

Anorectal Disease. High fistula, referred to as rectovaginal fistula, are communications to the rectum, proximal to the anal sphincter. These often involve the posterior vaginal fornix. Low fistula are anovaginal, which are communications from the anal sphincter complex to the lower half of the vagina [34]. Women with rectovaginal or anovaginal fistulae present with stool, gas, or odorous Anorectal Disease mucopurulent discharge from the vagina. These symptoms may be confused for incontinence. Other symptoms include dyspareunia, perineal pain, and recurrent vaginal infections. Rectovesicular fistulae are characterized by the clinical presentation of pneumaturia or fecaluria, which are pathognomonic [1]. Recurrent urinary tract infection may also be a presenting manifestation. Diverticulitis, CD, colorectal or pelvic malignancies, radiation, iatrogenic injury, and postoperative complications are the most common causes. CT Pelvis The appropriate CT protocol for imaging a patient with an anorectal complaint depends upon the presentation and differential diagnosis. IV contrast is preferred to a noncontrast examination to help visualize and characterize fluid collections, abscesses, and fistulous tracts. CT without contrast is not useful in this clinical scenario. CT with and without IV contrast would only be useful when there is benefit from dual-phase imaging, but is not typically performed in this scenario. Water-soluble rectal contrast is generally not necessary to diagnose a rectal abscess and may be challenging to administer, depending on symptom severity. However, rectal contrast may help delineate perforation or leak in a patient with a history of trauma or recent surgery. Water-soluble rectal contrast is preferred over barium to avoid the possibility of barium spilling into the peritoneal cavity or spaces of the extraperitoneal pelvis. Water-soluble rectal contrast is also preferred in a patient who could potentially be undergoing surgery.


Anorectal Disease

Anorectal Disease. CT provides important information in the diagnosis of the underlying etiology of the fistula, as well as detecting the course and locations of fistulae. To our knowledge, there are no data in the literature regarding the use of IV contrast in the detection of rectovaginal or rectovesicular fistula. Water-soluble contrast should be placed in the bowel or bladder to try to opacify fistulous tracts, depending upon the clinically suspected location of the tract. The bladder can be opacified retrograde (CT cystogram) or antegrade with delayed imaging after IV contrast administration. Kuhlman et al [35] reported an accuracy of 60% for the CT detection of enterovaginal or vesicovaginal fistula by the identification of contrast material in the vagina from the bowel or bladder. In a study of 37 patients with colovaginal and colovesicular fistulae, CT had a diagnostic sensitivity of 76.5% for fistula detection and 94.1% for defining the etiology of the fistula [1]. However, this study does not report how the diagnosis of fistula was made and what type of contrast material was used. Fluoroscopy Contrast Enema Fluoroscopic contrast enemas performed for the diagnosis of perforation or leak, rectovaginal or rectovesicular fistula, pouchitis, or proctitis can be performed with water-soluble contrast or barium. Though this procedure is reported to have low sensitivity and specificity as detailed in the following paragraph, it may be useful for observing subtle fistulas. In general, water-soluble contrast is preferred if a leak or perforation are suspected to avoid barium spillage into the peritoneal cavity or extraperitoneal pelvis. Using barium may also interfere with a subsequent CT scan because of the streak artifact that it causes on CT. Care should be taken not to inadvertently obscure a distal fistula with the enema or catheter tip or the balloon of a catheter. The performance of contrast enema for the detection of rectovaginal fistulas is reported in small series from older published literature.