Preprocedural Planning for Transcatheter Aortic Valve Replacement. For this document, the panel only considered the 2 clinical tasks required for preprocedure screening: (Variant 1) assessment of aortic annulus and aortic root, to help guide the choice of the valve prosthesis, and (Variant 2) assessment of supravalvular aorta and vascular access for potential determination of vascular access site and road mapping the desired device delivery. Special Imaging Considerations For the purposes of distinguishing between CT and CT angiography (CTA), ACR Appropriateness Criteria topics use the definition in the ACR-NASCI-SIR-SPR Practice Parameter for the Performance and Interpretation of Body Computed Tomography Angiography (CTA) [33]: All elements are essential: 1) timing, 2) reconstructions/reformats, and 3) 3-D renderings. Standard CTs with contrast also include timing issues and reconstructions/reformats. Only in CTA, however, is 3-D rendering a required element. This corresponds to the definitions that the CMS has applied to the Current Procedural Terminology codes. aMassachusetts General Hospital and Harvard Medical School, Boston, Massachusetts. bResearch Author, South Texas Radiology Group, P.A., San Antonio, Texas. cUniversity of Michigan, Ann Arbor, Michigan. dPanel Chair, Brigham & Women's Hospital, Boston, Massachusetts. ePanel Chair, Cleveland Clinic, Cleveland, Ohio. fPanel Vice-Chair, Mayo Clinic, Rochester, Minnesota. gKnight Cardiovascular Institute, Oregon Health & Science University, Portland, Oregon; Society of Cardiovascular Computed Tomography. hSanger Heart and Vascular Institute, Charlotte, North Carolina; American Society of Echocardiography. iUT Southwestern Medical Center, Dallas, Texas; Commission on Nuclear Medicine and Molecular Imaging. jUniversity of Washington School of Medicine, Seattle, Washington; Society for Cardiovascular Magnetic Resonance. kEmory University, Atlanta, Georgia; Committee on Emergency Radiology-GSER.


Preprocedural Planning for Transcatheter Aortic Valve Replacement. lWashington University School of Medicine, Saint Louis, Missouri; American Association for Thoracic Surgery. mCleveland Clinic, Cleveland, Ohio. nStanford University, Stanford, California. oMercyhealth, Rockford, Illinois. pSpecialty Chair, Duke University Medical Center, Durham, North Carolina. qSpecialty Chair, Brigham & Women's Hospital, Boston, Massachusetts. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through representation of such organizations on expert panels. Participation on the expert panel does not necessarily imply endorsement of the final document by individual contributors or their respective organization. Reprint requests to: publications@acr.org Transcatheter Aortic Valve Replacement Imaging should allow characterization and reporting of aortic valve morphology in each patient and degree of calcification [34,35]. Calcified raphe for bicuspid valves and excess leaflet calcification are known to be associated with an increased risk of procedural complications and midterm mortality [36]. The annulus size for bicuspid aortic valve should be measured and reported in the same fashion as for tricuspid aortic valves, even though the basal attachments of the 2 leaflets of bicuspid aortic valve provide only 2 landmarks out of a necessary 3 landmarks to define an annular plane in space [37]. In addition, it is important to evaluate coronary ostial heights, sinus of Valsalva widths, sinotubular junction diameters, and annular/left ventricular outflow tract (LVOT) calcification, all of which are predictive of complication risks with TAVR. OR Discussion of Procedures by Variant Variant 1: Preintervention planning for transcatheter aortic valve replacement: assessment of aortic root. Initial imaging. Aortography Chest There is no relevant literature to support the use of aortography chest for annulus sizing and assessment of aortic root.


Preprocedural Planning for Transcatheter Aortic Valve Replacement. CT Chest With IV Contrast There is no relevant literature to support the use of chest CT with intravenous (IV) contrast for annulus sizing and assessment of aortic root. CT Chest Without and With IV Contrast There is no literature in support of chest CT without and with IV contrast for annular sizing and assessment of aortic root. CT Chest Without IV Contrast There is no literature in support of chest CT without IV contrast for annular sizing and assessment of aortic root. Aortic calcification can; however, be assessed on CT chest without IV contrast. Harbaoui et al [38] evaluated ascending aortic calcifications in 189 patients undergoing TAVR and noted ascending aortic calcification (tertile 3 versus tertile 1) appeared predictive of heart failure (hazard ratio [HR]: 2.29; 95% confidence interval [CI], 1.12- 4.66; P = . 023). Transcatheter Aortic Valve Replacement (14% versus 35%; P = . 003). In a prospective study of 266 patients, 133 consecutive patients underwent TAVR with valve prosthesis size recommendation based on a CTA sizing algorithm and were compared with another cohort of 133 consecutive patients who underwent TAVR with valve prosthesis size recommendation based on a combination of echocardiogram measurements and angiographic images. The authors demonstrated a significant reduction in the incidence of paravalvular leak of 5.3% (7/133) in the CT group and 12.8% (17/133) in the control group (P = . 032) as a primary endpoint and aortic annulus rupture, and they demonstrated a significant reduction in in-hospital deaths of 3.8% (5/133) in the CTA group and 11.3% (15/133) in the control group (P = . 02) as a secondary endpoint [15]. CTA Chest With IV Contrast There is no literature to support the use of CTA chest with IV contrast for the assessment of the aortic root; however, in absence of motion artifacts, the annulus can be evaluated for size, calcifications, coronary ostial heights, and sinus of Valsalva diameters.


Preprocedural Planning for Transcatheter Aortic Valve Replacement. CTA Coronary Arteries With IV Contrast There is no relevant literature to support the use of CTA coronary arteries with IV contrast as the initial imaging modality for the assessment of aortic root. Although CTA coronary arteries with IV contrast can evaluate coronary anatomy and stenosis, which can be helpful in the management of patients undergoing TAVR, it does not impact selection of device type and/or size. A multiphase coronary CTA can also be used for evaluation and sizing of the annulus and aortic root. MRA Chest With IV Contrast Although a majority of the evidence focuses on noncontrast MR angiography (MRA) techniques for root assessment, contrast-enhanced MRA may provide faster acquisition [45]. MRA Chest Without and With IV Contrast In a prospective study of 69 patients, Ruile et al [46] observed good reproducibility of aortic annulus dimensions and calcifications in comparison with cardiac CTA, even in the presence of arrhythmias in the all-comers pre-TAVR population and useful in patients at an increased risk for contrast-induced nephropathy with an agreement for hypothetical prosthesis sizing in 63 of 67 (94%) patients for systolic CTA and modeled systolic MRA. Also, excellent correlation was reported for the distance to the right or left coronary ostium between diastolic CTA and diastolic MRA. The role of MRA is; however, limited when there is a high-susceptibility artifact, magnetic field incompatible devices, and severe arrhythmia. Finally, the MRA examination is a technically more complex examination, with longer study time and a higher required degree of patient cooperation, which can be problematic for patients with a poor clinical condition [47]. MRA Coronary Arteries Without and With IV Contrast There is no relevant literature to support the use of MRA coronary arteries without and with IV contrast as the initial imaging modality for the assessment of aortic root.


Preprocedural Planning for Transcatheter Aortic Valve Replacement. Transcatheter Aortic Valve Replacement MRA Coronary Arteries Without IV Contrast There is no relevant literature to support the use of MRA coronary arteries without IV contrast as the initial imaging modality for the assessment of aortic root. Transcatheter Aortic Valve Replacement US Echocardiography Transesophageal In a retrospective analysis of 101 patients who underwent both preoperative MDCT and 3-D TEE for aortic annulus sizing for TAVR planning, the automatic software measurements showed very good agreement with manual values obtained using MDCT and 3-D TEE, with the interactive approach having slightly narrower limits of agreement. The latter also had excellent intra- and interobserver variability. Both fully automatic and interactive analyses showed excellent test-retest reproducibility, with the first having a faster analysis time. Finally, either approach led to good sizing agreement against the true implanted sizes (>77%) and against MDCT-based sizes (>88%) [53]. A retrospective analysis of 31 patients who underwent transcatheter aortic valve implantation showed an excellent correlation between the aortic annulus measurements obtained by both manual 3-D TEE method and by the automatic software method (intraclass correlation coefficient: 0.731 (0.508-0.862), r: 0.742) for aortic annulus diameter and (intraclass correlation coefficient: 0.723 (0.662-0.923), r: 0.723) for the aortic annulus area, with no significant differences regardless of the method used. The interobserver variability was superior for the automatic measurements than for the manual ones. In a subgroup of 10 patients, they also found an excellent correlation between the automatic measurements and those obtained by MDCT (intraclass correlation coefficient: 0.941 (0.761- 0.985), r: 0.901) for aortic annulus diameter and (intraclass correlation coefficient: 0.853 (0.409-0.964), r: 0.744) for the aortic annulus area.


Preprocedural Planning for Transcatheter Aortic Valve Replacement. Thus, new automatic 3-D TEE software allows modeling and quantifying the aortic root from 3-D TEE data with high reproducibility and showed good correlation between the automated measurements and other 3-D validated techniques, thus supporting its use in clinical practice as an alternative to MDCT before transcatheter aortic valve implantation for annular sizing (annular area, annular mean diameter and perimeter, sinotubular junction diameter, sinus of Valsalva diameter) [54]. Although TEE can be used intraprocedurally, it has a limited role for preprocedural assessment. Additionally there is a paucity of TEE data for evaluating aortic root features such as coronary ostial height and subannular calcification [55]. US Echocardiography Transthoracic Resting Although ultrasound (US) echocardiography transthoracic resting can diagnose aortic stenosis and can be used during TAVR procedures, there is no relevant literature to support its use for annulus sizing and assessment of aortic root. Variant 2: Preintervention planning for transcatheter aortic valve replacement: assessment of supravalvular aorta and vascular access. Initial imaging. Aortography Chest, Abdomen, and Pelvis There is no relevant literature to support the use of aortography of the chest, abdomen, and pelvis as the initial imaging modality for the evaluation of vascular access before a TAVR procedure. CT Abdomen and Pelvis With IV Contrast There is no relevant literature to support the use of CT abdomen and pelvis with IV contrast as the initial imaging modality for the valuation of vascular access for a TAVR procedure. CT Abdomen and Pelvis Without and With IV Contrast There is no relevant literature to support the use of CT abdomen and pelvis without and with IV contrast as the initial imaging modality for evaluation of vascular access for a TAVR procedure.


Preprocedural Planning for Transcatheter Aortic Valve Replacement. CT Abdomen and Pelvis Without IV Contrast CT abdomen and pelvis without IV contrast cannot assess lumen size and patency, but mural calcifications can be assessed. In a comparative study of 103 of 588 patients undergoing both noncontrast CT and angiography, with 17 sheath-related complications, Okuyama et al [23] showed there was no difference between noncontrast CT and angiography: area under the curve 0.79 (95% CI, 0.70-0.86) versus area under the curve 0.73 (95% CI, 0.63-0.81) in predicting sheath-related complications. CT Chest, Abdomen, and Pelvis With IV Contrast There is no relevant literature to support the use of CT chest, abdomen, and pelvis with IV contrast as the initial imaging modality for the evaluation of vascular access before a TAVR procedure. CT Chest, Abdomen, and Pelvis Without and With IV Contrast There is no relevant literature to support the use of CT chest, abdomen, and pelvis without and with IV contrast as the initial imaging modality for the evaluation of vascular access before a TAVR procedure. Aortic calcification can: however, be assessed on CT chest, abdomen, and pelvis without and with IV contrast. Harbaoui et al [38] evaluated 189 patients undergoing TAVR for total aortic calcifications, ascending aortic calcification, descending Transcatheter Aortic Valve Replacement aorta calcifications, and abdominal aorta calcifications. In their study, total aortic calcification (tertile 3 versus tertile 1) was significantly and strongly associated with cardiac mortality (HR: 16.74; 95% CI, 2.21-127.05; P = . 006) and all-cause mortality (HR: 2.39; 95% CI, 1.18-4.84; P = . 015). Each aortic calcified segment was associated with cardiac mortality, whereas only ascending aortic calcification (tertile 3 versus tertile 1) appeared predictive of heart failure (HR: 2.29; 95% CI, 1.12-4.66; P = . 023).


Preprocedural Planning for Transcatheter Aortic Valve Replacement. CT Chest, Abdomen, and Pelvis Without IV Contrast There is no relevant literature to support the use of CT chest, abdomen, and pelvis without IV contrast as the initial imaging modality for the evaluation of vascular access before a TAVR procedure. CT chest, abdomen, and pelvis without IV contrast cannot assess lumen size and patency, but mural calcifications can be assessed. CT Chest With IV Contrast There is no relevant literature to support the use of CT chest with IV contrast as the initial imaging modality for the evaluation of vascular access before a TAVR procedure. CT Chest Without and With IV Contrast There is no relevant literature to support the use of CT chest without and with IV contrast as the initial imaging modality for the evaluation of vascular access before a TAVR procedure. CT Chest Without IV Contrast There is no relevant literature to support the use of CT chest without IV contrast as the initial imaging modality for the evaluation of vascular access before a TAVR procedure. CT chest without IV contrast cannot assess lumen size and patency, but mural calcifications can be assessed. Additionally, circumferential aortic calcifications (porcelain aorta) can be detected, which may complicate the device delivery [56]. CT Heart Function and Morphology With IV Contrast There is no relevant literature to support the use of CT heart function and morphology with IV contrast as the initial imaging modality for the evaluation of vascular access before a TAVR procedure. Preprocedural CT heart function and morphology with IV contrast can help in identifying left ventricular apex and assess myocardial thickness and left ventricular orientation and in guiding planned mini-thoracotomy. CTA Abdomen and Pelvis With IV Contrast CTA imaging can assess luminal size, patency, vessel tortuosity, and the extent of mural calcifications.


Preprocedural Planning for Transcatheter Aortic Valve Replacement. Kinnel et al [57] evaluated aortoiliac and femoral arteries in their comparative study of 175 patients for abdominal aortic tortuosity and noted abdominal aorta tortuosity in 28 patients (16%) with strong association with the occurrence of a complication (adjusted odds ratio 2.7; 95% CI, 1.1-6.6; P = . 03). CTA Chest, Abdomen, and Pelvis With IV Contrast CTA allows the assessment of vessel size, calcifications, and minimal luminal diameters [58]. In a comparative study of 283 of 588 patients undergoing both contrast CT and angiography, with 35 sheath-related complications, Okuyama et al [23] showed a greater predictive value for vascular complications with contrast CT than angiography by area under the curve (P < . 001): 0.87 (95% CI, 0.82-0.91) versus 0.72 (95% CI, 0.66-0.77). Recent data from the VICTORY registry of 240 patients also showed a role of CTA in assessing tortuosity. In the study, the authors noted a higher incidence of access and bleeding complications in patients with a higher iliofemoral tortuosity score (56 [36.8%] versus 17 [19.3%]; P = . 003). Additionally, in a multivariate logistic regression analysis, only the higher iliofemoral tortuosity score was a significant predictor of the primary endpoint (odds ratio, 2.11; 95% CI, 1.09-4.05; P = . 026) [59]. CTA can also be used to evaluate alternate access sites like direct aortic or subclavian/axillary access. Arnett et al [60] retrospectively evaluated 208 patients undergoing CTA and reported on the compared axillary arteries and demonstrated substantially lower rates of significant stenosis (2% versus 12%, P < . 01) and significantly lower rates of moderate to severe calcification disease (9% versus 64%, P < . 01) than iliofemoral arteries. CTA Chest With IV Contrast CTA of the chest with IV contrast is helpful for patients undergoing TAVR [49] for the assessment of supravalvular aorta.


Preprocedural Planning for Transcatheter Aortic Valve Replacement. It has been demonstrated that a subclavian approach leads to morbidity and mortality rates similar to those observed with the transfemoral approach [61]. CTA can also be used to evaluate alternate access sites like direct aortic or subclavian/axillary access. Arnett et al retrospectively evaluated 208 patients undergoing CTA and reported on the compared axillary arteries and demonstrated substantially lower rates of significant stenosis (2% Transcatheter Aortic Valve Replacement versus 12%, P < . 01) and significantly lower rates of moderate to severe calcification disease (9% versus 64%, P < . 01) than iliofemoral arteries [60]. MRA Abdomen and Pelvis Without and With IV Contrast There is limited data supporting MRA abdomen and pelvis without and with IV contrast as the initial imaging modality for the evaluation of vascular access before a TAVR procedure. MRA Chest, Abdomen, and Pelvis With IV Contrast There is no relevant literature supporting the use of MRA chest, abdomen, and pelvis with IV contrast for the assessment of supra ventricular aorta and vascular access. MRA chest, abdomen, and pelvis with IV contrast can; however, be used as an alternate option in a selected patient population to assess supravalvular aorta and vascular access. MRA Chest With and Without IV Contrast There is no relevant literature supporting the use of MRA chest with and without IV contrast for the assessment of supra ventricular aorta and vascular access; however, MRA chest with and without IV contrast can be used as an alternate option in a selected patient population to assess supravalvular aorta and vascular access. US Duplex Doppler Chest, Abdomen, and Pelvis There is no relevant literature to support the use of US duplex doppler chest, abdomen, and pelvis as the initial imaging modality for evaluation of vascular access before a TAVR procedure.


Acute Trauma to the Knee

Acute Trauma to the Knee.  Introduction/Background Acute bone and soft-tissue injuries to the knee may result from low- or high-energy trauma and are commonly seen in emergency departments as well as in outpatient practices [1]. The most common acute knee injuries result from a direct blow, a fall, or a twisting injury [2,3]. The fracture risk increases with age, likely secondary to decreased bone mineral density, increased frequency of blunt injury, and inability to protect the knee during a fall [3]. An estimated 6.6 million knee injuries presented to emergency departments in the United States from 1999 through 2008, for a rate of 2.29 knee injuries per 1,000 population. Prompt and accurate diagnosis facilitates adequate management and may prevent potential complications [1,4]. After thorough history and clinical examination, radiographs are usually the initial imaging modality in the evaluation of the acutely injured knee [1]. Adequate clinical examination and appropriate application of the established decision-making rules can reduce the number of radiographic studies in the setting of acute knee injuries with a potential benefit of reducing health care costs and decreasing radiation exposure to the patient [1,5,6]. Treatment options for acute traumatic knee injuries depend on the severity of injury and patient factors and include conservative or surgical management [1]. Special Imaging Considerations For the purpose of this document, point-of-care ultrasound (US) is not discussed or listed in the variant tables. For the purposes of distinguishing between CT and CT angiography (CTA), ACR Appropriateness Criteria topics use the definition in the ACR-NASCI-SIR-SPR Practice Parameter for the Performance and Interpretation of Body Computed Tomography Angiography (CTA) [7]. All elements are essential: 1) timing, 2) reconstructions/reformats, and 3) 3-D renderings. Standard CTs with contrast also include timing issues and recons/reformats. Only in CTA; however, is 3-D rendering a required element.


Acute Trauma to the Knee

Acute Trauma to the Knee. This corresponds to the definitions that the CMS has applied to the Current Procedural Terminology codes. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels. Participation by representatives from collaborating societies on the expert panel does not necessarily imply individual or society endorsement of the final document. Reprint requests to: publications@acr.org Acute Trauma to the Knee Discussion of Procedures by Variant Variant 1: Adult or child 5 years of age or older. Fall or acute twisting trauma to the knee. No focal tenderness, no effusion, able to walk. Initial imaging. CT Knee In the absence of focal tenderness and joint effusion in a patient who is able to walk, CT is not used as the initial imaging study for the evaluation of acute trauma to the knee. MR Arthrography Knee MR arthrography is not routinely used as the initial imaging study for the evaluation of acute trauma to the knee. MRA Knee MR angiography (MRA) is not routinely used as the initial imaging study for the evaluation of acute trauma to the knee. MRI Knee MRI is not routinely used as the initial imaging study for the evaluation of acute trauma to the knee. Radiography Knee With no clinical symptoms in the injured knee, including lack of focal tenderness and joint effusion, and with ability to walk, knee radiographs may be indicated if a patient >55 years old per Ottawa rules or >50 years old or <12 years old per Pittsburgh rule criteria [5, 6, 10]. If the patient is between 5 and 12 years, they fall outside the age range for both the Ottawa and Pittsburgh rules and radiographs may be beneficial despite lack of clinical symptoms. Radiographs are commonly performed in the setting of acute knee injuries but have a low yield for showing fractures.


Acute Trauma to the Knee

Acute Trauma to the Knee. In a retrospective review of 1,967 patients with acute knee injuries by Stiell et al [2], 74.1% of patients had knee radiography, and only 5.2% of these had fractures. Therefore, to avoid a large number of negative radiographic studies, development of the inclusion criteria for obtaining knee radiographs in the setting of the acute trauma was needed. The two most commonly used clinical decision criteria, the Ottawa Knee Rule and the Pittsburgh Decision Rule, can help to decide when to perform radiographs in acute knee trauma [5,6,8]. Pittsburgh Decision Rule The Pittsburgh Decision Rule states that patients with acute knee trauma who are <12 years old or >50 years old should have radiographs as well as patients who cannot take 4 weight-bearing steps in the emergency department [5,6]. In their prospective study in 178 patients with acute knee trauma with the Ottawa rule criteria applied, Jenny et al [8] found a 35% decrease in the number of radiographic examinations with 100% sensitivity for detecting knee fracture. Similarly, Cheung et al [6] found a 23% reduction of knee radiographs in 90 patients if the Ottawa rule criteria were applied, although they did report 1 patient who had a fracture and did not meet any of the clinical criteria, but this fracture was radiographically occult and visible only by MRI. In their retrospective study on 106 acute knee trauma patients, Konan et al [5] evaluated the role of the Ottawa and Pittsburgh rules to reduce the unnecessary use of radiographs following knee injury. One hundred and one patients (95%) had radiographs of their injured knees. Only 5% of these patients had a fracture on radiographs, all with Ottawa and Pittsburgh knee rules fulfilled. Using the Ottawa rules, 27 radiographic studies (25%) could have been Acute Trauma to the Knee avoided without missing a fracture. Using the Pittsburgh rules, 32 radiographic studies (30%) could have been avoided.


Acute Trauma to the Knee

Acute Trauma to the Knee. In this study, both the Ottawa and Pittsburgh rules showed high sensitivity in detecting knee fractures [5]. Other clinical decision criteria were tested. In an emergency department, in a study of 242 patients >17 years with isolated knee injuries sustained 24 hours previously, Weber et al [3] were able to exclude clinically significant fractures in patients >18 years who could walk without limping or if there was a twisting injury to the knee and no joint effusion. These clinical decision rules were effective in detecting knee fractures with 100% sensitivity and with sufficient specificity to eliminate 29% of knee radiographs [3]. Bone Scan with SPECT or SPECT/CT Knee Tc-99m bone scan with single-photon emission computed tomography (SPECT)/CT knee is not routinely used as the initial imaging study for the evaluation of acute trauma to the knee. US Knee US is not routinely used as the initial imaging study for the evaluation of acute trauma to the knee. Variant 2: Adult or child 5 years of age or older. Fall or acute twisting trauma to the knee. One or more of the following: focal tenderness, effusion, inability to bear weight. Initial imaging. CT Knee CT is not routinely used as the initial imaging study for the evaluation of acute trauma to the knee. MR Arthrography Knee MR arthrography is not routinely used as the initial imaging study for the evaluation of acute trauma to the knee. MRA Knee MRA is not routinely used as the initial imaging study for the evaluation of acute trauma to the knee. MRI Knee MRI is not routinely used as the initial imaging study for the evaluation of acute trauma to the knee. Radiography Knee With one or more positive Ottawa rule criteria, including focal tenderness and/or inability to bear weight, radiographs should be the initial imaging modality for the evaluation of acute trauma to the knee [5,6,8].


Acute Trauma to the Knee

Acute Trauma to the Knee. Bone Scan with SPECT or SPECT/CT Knee Tc-99m bone scan with SPECT/CT knee is not routinely used as the initial imaging study for the evaluation of acute trauma to the knee. US Knee US is not routinely used as the initial imaging study for the evaluation of acute trauma to the knee. Acute Trauma to the Knee Variant 3: Adult or skeletally mature child. Fall or acute twisting trauma to the knee. No fracture seen on radiographs. Suspect occult fracture or internal derangement. Next study. CT Knee CT may be performed as the next imaging study for the evaluation of suspected radiographically occult knee fractures. Several studies reported CT to be superior to knee radiographs in detection and classification of fractures. In a study by Mustonen et al [12], CT showed 100% and radiographs 83% sensitivity in detection of tibial plateau fractures, and CT was superior in further characterization of fracture severity. In the setting of acute knee trauma, Mui et al [13] reported 80% sensitivity and 98% specificity of the CT examination in detecting bony avulsion fractures and a high negative predictive value for excluding ligamentous injuries, but MRI remained necessary for the preoperative detection of meniscal injury. Peltola et al [14] compared dual-energy CT examinations with MRI studies as a reference standard in 18 patients with acute knee trauma and reported dual-energy CT had 79% sensitivity and 100% specificity in detecting anterior cruciate ligament (ACL) ruptures [14]. In a study by Heffernan et al [15], 64-channel multidetector CT showed 87.5% to 100% sensitivity and 100% specificity for detection of the ACL tears. As on MRI, secondary signs, such as buckling of the posterior cruciate ligament, were also useful in their diagnosis.


Acute Trauma to the Knee

Acute Trauma to the Knee. In this study, multidetector CT showed a low sensitivity for other soft- tissue injuries at the knee; however, its high specificity indicated that apparent posterior cruciate ligament, meniscal, and collateral ligament tears can reliably be treated as true-positive findings [15]. The dual-energy CT virtual noncalcium technique can subtract calcium from cancellous bone, allowing detection [16-18] and possibly grading of the post-traumatic bone marrow contusions [18]. However, MRI is superior to CT in detection of bone marrow abnormalities and meniscal and ligamentous injuries and may be subsequently performed as clinically indicated. MR Arthrography Knee With negative radiographs, MR arthrography is not routinely used as the next imaging study for the evaluation of suspected occult knee fractures or internal derangement. MRA Knee With negative radiographs, MRA is not routinely used as the next imaging study for the evaluation of suspected occult knee fractures or internal derangement. MRI Knee MRI has many distinct advantages for the evaluation of the injured knee in the setting of negative radiographs. The majority of patients (93.5%) who present with acute knee injuries in the emergency department sustained soft- tissue injuries rather than osseous injuries [19]. MRI is a proven valuable tool in the treatment decision-making process, allowing earlier surgical intervention by obtaining a more accurate diagnosis [20,21]. Frobell et al [22] reported a low diagnostic benefit of the initial clinical examination in the setting of acute knee trauma with higher- than-suspected incidence of the ACL injuries on MRI. In randomized studies of patients with knee injuries [23,24], MRI findings shortened the diagnostic completion workup, reduced the number of additional diagnostic procedures, and improved quality of life in the first 6 weeks, potentially reducing productivity loss.


Acute Trauma to the Knee

Acute Trauma to the Knee. A retrospective study by Cecava et al [25] showed that knee radiography is a highly specific screening test for internal derangement in patients <40 years old with acute knee injury. In this patient population, knee effusion >10 mm on lateral radiograph should prompt consideration for the knee MRI examination, which can potentially decrease delayed diagnosis, improve patient outcomes, and decrease disability [25]. Magee et al [26] reported 96% sensitivity and 97% specificity of 3T MRI in the detection of meniscal tears in correlation with arthroscopy. However, a study by Van Dyck et al [21] showed similar high sensitivities and specificities of routine 3T and 1.5T MRI examinations in the evaluation of meniscal and ACL tears with arthroscopic correlation. Routine 3T MRI protocol did not significantly improve accuracy for evaluating the knee menisci and ACL compared with a similar 1.5T MRI protocol. MRI can diagnose the patterns and severity of bone marrow contusions that frequently have an association with the specific mechanisms of injury and can predict associated soft-tissue injuries [27,28]. In a study by Song et al [28], Acute Trauma to the Knee in the setting of the acute noncontact ACL injury, both the presence and the severity of lateral bone contusions were associated with high-grade pivot-shift, concomitant lateral meniscal lesions as well as anterolateral ligament abnormality. Klengel et al [29] found that the apparent diffusion coefficient maps are more sensitive than corresponding proton density-weighted fat-saturated turbo spin-echo MRI sequences for detection of bone marrow lesions after knee trauma and allowed detection of significantly more and larger bone marrow lesions. Additionally, apparent diffusion coefficient map evaluation improved diagnostic performance in regions with insufficient spectral fat saturation, such as the patella.


Acute Trauma to the Knee

Acute Trauma to the Knee. Koster et al [30] showed that the presence of a bone contusion on MRI after acute knee trauma is highly predictive of the development of focal osteoarthritis 1 year after trauma. MRI facilitates diagnosis of the anterolateral ligament injuries that have frequent association with ACL injuries and anterolateral knee instability, of which a minority are associated with Segond fractures [31]. In a study by Kosy et al [32], MRI detected a larger number of anterolateral ligament injuries in association with the ACL injuries within 6 weeks of the acute knee trauma compared with scans performed later, which suggests that some injuries may resolve or become less visible with increased chronicity. MRI is proven helpful in detection and characterization of posterolateral corner injuries, which can be associated with the ACL ruptures and, if missed, may lead to considerable morbidity. In a study by Temponi et al [33], concomitant posterolateral corner injuries and the ACL ruptures were present in 19.7% of patients on MRI studies. Precise location and classification of the ACL tears on the MRI study may help in preoperative planning, in particular with a growing interest in this ligament preservation technique [34]. MRI can change management from surgical to conservative in up to 48% of patients presenting with a locked knee, which is usually an indication for arthroscopic procedure [35,36]. Bone Scan with SPECT or SPECT/CT Knee Tc-99m bone scan would not be the next best imaging study to evaluate for radiographically occult fractures and/or internal derangement. Tc-99m-methylene diophosphate bone SPECT/CT scan has been suggested as an alternative to MRI in evaluating suspected bone contusions and meniscal and ACL tears in the setting of acute knee trauma. A SPECT study by Even-Sapir et al [37] with arthroscopic and MRI correlation showed promising results in diagnosis of the ACL and meniscal tears and the associated bone contusions in patients with acute knee trauma.


Acute Trauma to the Knee

Acute Trauma to the Knee. Another study by Siegel et al [38] suggested that the degree of radiotracer uptake in the knee, as determined by SPECT, positively correlates with the severity of pathology seen at arthroscopy. However, a more recent SPECT study with arthroscopic correlation by Wertman et al [39] showed a lower sensitivity, specificity, and accuracy than MRI in evaluating meniscal injuries. US Knee US is not used as the next best imaging study to evaluate for radiographically occult fractures and/or internal derangement. US is an excellent and easily performed imaging study in detection of knee joint effusions. However, because of its technical limitations, US may only evaluate the outer bone surface and has a limited role in detection of the occult knee fractures. Therefore, this imaging modality is not routinely used for the evaluation of suspected occult knee fractures but may detect a lipohemarthrosis, which is typically associated with intra-articular fractures. A comparison of US studies with radiography and CT examinations by Bonnefoy et al [40] serving as the reference standard and using a knee lipohemarthrosis as a criterion, yielded a sensitivity of and specificity of 94% for US detection of acute intra-articular fractures. A recent study by Klos et al [41] showed a higher prevalence of Segond avulsions fractures on US studies than previously reported in literature on the MRI or radiography. The lateral femoral condyle impaction injury was the best variable in predicting the presence of a Segond fracture [41]. Acute Trauma to the Knee US study by Dai et al including 551 patients from 7 prospective studies revealed pooled sensitivity of 88% and specificity of 90% in diagnosis of meniscal injuries [46]. Variant 4: Skeletally immature child. Fall or acute twisting trauma to the knee. No fracture seen on radiographs. Suspect occult fracture or internal derangement. Next study.


Acute Trauma to the Knee

Acute Trauma to the Knee. CT Knee With negative radiographs, CT may be performed as the next imaging study for the evaluation of suspected radiographically occult knee fractures [12] and bone marrow contusions [16-18]. CT may diagnose or predict ligamentous injuries [14,15,50,51] and predict meniscal [15,50,51] injuries. However, MRI is superior to CT in evaluation of bone marrow lesions [27-29], meniscal [21,26] and ligamentous [21,31-34] injuries, and may be subsequently performed as clinically indicated. MR Arthrography Knee With negative radiographs, MR arthrography is not routinely used as the next imaging study for the evaluation of suspected occult knee fractures or internal derangement. MRA Knee With negative radiographs, MRA is not routinely used as the next imaging study for the evaluation of suspected occult knee fractures or internal derangement. MRI Knee MRI should be the next imaging modality to evaluate for the presence of radiographically occult fractures and/or internal derangements of the acutely injured knee. With its superb contrast resolution and multiplanar imaging capability, MRI is proven to be a highly accurate imaging modality in the evaluation of bone marrow contusions and occult fractures [27-29] as well as meniscal [21,26] and ligamentous injuries [21,31-34]. Bone Scan with SPECT or SPECT/CT Knee Tc-99m bone scan with SPECT/CT would not be the next best imaging study to evaluate for radiographically occult fractures and/or internal derangement. Even-Sapir et al [37] showed promising results of a SPECT study in diagnosis of the ACL and meniscal tears and the associated bone contusions in patients with acute knee trauma with arthroscopic and MRI correlation. However, a more recent SPECT study with arthroscopic correlation by Wertman et al [39] showed a lower sensitivity, specificity, and accuracy than MRI in evaluating meniscal injuries.


Acute Trauma to the Knee

Acute Trauma to the Knee. US Knee US would not be the next best imaging study to evaluate for radiographically occult fractures and/or internal derangement of the acutely injured knee. However, US may demonstrate a lipohemarthrosis, indicating the presence of an intra-articular fracture [40]. US is an excellent imaging modality for the diagnosis of quadriceps tendon tears [42] with good performance in the evaluation of the meniscal [44-46] and ligamentous [47-49] injuries. However, the utility of US in the evaluation of the knee menisci, cruciate and collateral ligaments, and periarticular soft tissues varies depending on patient factors. Variant 5: Adult or child 5 years of age or older. Fall or acute twisting trauma to the knee. Tibial plateau fracture on radiographs. Suspect additional bone or soft-tissue injury. Next study. CT Knee In patients with radiographic diagnosis of the tibial plateau fracture, CT is frequently performed for further classification and characterization of the fracture severity [12,52] and may predict or diagnose ligamentous injuries [13-15,50,51] and predict meniscal injuries [15,50]. A study by Spiro et al [50] found that the amount of articular surface depression on CT is a predictor of meniscal and ligamentous injuries and can suggest when an MRI is indicated to confirm or exclude meniscal and ligamentous injuries [50]. In a study by Mustonen et al [12], CT showed 100% sensitivity and radiographs 83% sensitivity in detection of tibial plateau fractures, and CT was superior in further characterization of fracture severity. Chang et al [52] reported that CT-reconstructed images Acute Trauma to the Knee enhance the morphological subclassification of the medial tibial plateau fractures (Schatzker type IV) with common involvement of posterolateral quadrants. In the setting of acute knee trauma, Mui et al [13] reported 80% sensitivity and 98% specificity of the CT examination in detecting bony avulsion fractures.


Acute Trauma to the Knee

Acute Trauma to the Knee. Tang et al [51] found that lateral tibial plateau depression of >11 mm and its specific part involvement on preoperative CT scans could help predict a higher risk of the lateral meniscus tear and the ACL avulsion fracture. MR Arthrography Knee With a radiographic diagnosis of tibial plateau fracture, MR arthrography of the knee is not performed to evaluate for additional bone or soft-tissue injury. MRA Knee With a radiographic diagnosis of tibial plateau fracture, MRA of the knee is not performed to evaluate for additional bone or soft-tissue injury. MRI Knee With a radiographic diagnosis of tibial plateau fracture, MRI would be the next best imaging modality to evaluate for the presence of additional radiographically occult fractures and/or internal derangements of the acutely injured knee. With its superb contrast resolution and multiplanar imaging capability, MRI is proven to be a highly accurate imaging modality in the evaluation of bone marrow contusions and occult fractures [27-29] as well as meniscal [21,26] and ligamentous injuries [21,31-34]. Bone Scan with SPECT or SPECT/CT Knee With a radiographic diagnosis of tibial plateau fracture, Tc-99m bone scan with SPECT/CT is not performed as the next best imaging study to evaluate for additional bone or soft-tissue injury. US Knee With a radiographic diagnosis of tibial plateau fracture, US is not performed as the next best imaging study to evaluate for additional bone or soft-tissue injury. Variant 6: Adult or child 5 years of age or older. Acute trauma to the knee. Mechanism unknown. Focal patellar tenderness, effusion, able to walk. Initial Imaging. CT Knee CT is not routinely used as the initial imaging study for the evaluation of acute trauma to the knee but is superior to knee radiographs in detection and classification of fractures [12]. MR Arthrography Knee MR arthrography is not routinely used as the initial imaging study for the evaluation of acute trauma to the knee.


Acute Trauma to the Knee

Acute Trauma to the Knee. MRA Knee MRA is not routinely used as the initial imaging study for the evaluation of acute trauma to the knee. MRI Knee MRI is not routinely used as the initial imaging study for the evaluation of acute trauma to the knee. MRI aids in diagnosis and further characterization of bone and soft-tissue injuries associated with transient lateral dislocation of the patella [53-55]. Bone Scan with SPECT or SPECT/CT Knee Tc-99m bone scan with SPECT/CT knee is not routinely used as the initial imaging study for the evaluation of acute trauma to the knee. US Knee US is not routinely used as the initial imaging study for the evaluation of acute trauma to the knee. Acute Trauma to the Knee Variant 7: Adult or child 5 years of age or older. Significant trauma to the knee (eg, motor vehicle accident, knee dislocation). Initial imaging. Arteriography Lower Extremity Vascular injury may be found in about 30% of patients following posterior knee dislocation [56]. Injuries of the popliteal artery require prompt surgical intervention to help limb preservation. Associated peroneal and tibial nerve injuries may cause significant morbidity and require an understanding of their pathophysiologic implications to maximize limb functionality [57]. Angiography has been the reference standard in the evaluation of vascular injuries associated with knee dislocations [58]. However, this is an invasive procedure with associated risk, and with the excellent performance of CTA and MRA, it is usually performed in selected cases [58]. CT Knee CT is not routinely used as the initial imaging study for the evaluation of acute trauma to the knee. CT is superior to knee radiographs in detection and classification of fractures [12]; however, without IV contrast, CT cannot detect vascular injuries. CTA Lower Extremity With suspected vascular injuries in the setting of knee dislocation, CTA is frequently used because it is less invasive and has a similarly high accuracy as conventional angiography [58-60].


Acute Trauma to the Knee

Acute Trauma to the Knee. MR Arthrography Knee In patients with significant acute knee trauma with suspected or possible dislocation, MR arthrography of the knee is not routinely used as the initial imaging study. MRA Knee MRI is an accurate method used in the evaluation of soft-tissue, osseous, and neural injuries after knee dislocation [61]. MRA may be performed simultaneously with MRI for evaluation of internal derangement and vascular injuries with less morbidity compared with conventional angiography [62]. Potter et al [61] reported their experience with popliteal fossa MRA with encouraging results and complete agreement between the MRA and conventional angiography in patients who had both studies. Similarly, in a study by Tocci et al [62], MRA has been shown to be as accurate and useful as conventional angiography in the evaluation of popliteal artery injuries of patients with knee dislocations. MRI Knee With its superb contrast resolution and multiplanar imaging capability, MRI is proven to be a highly accurate imaging modality in the evaluation of bone marrow contusions and occult fractures [27-29] as well as meniscal [21,26] and ligamentous injuries [21,31,32]. It can be performed in conjunction with MRA for evaluation of internal derangement and vascular injuries with less morbidity compared with conventional angiography [62]. Bone Scan with SPECT or SPECT/CT Knee In patients with significant acute knee trauma with suspected/possible dislocation, Tc-99m bone scan with SPECT/CT is not routinely used as the initial imaging study. US Knee In patients with significant acute knee trauma with suspected or possible dislocation, US is not routinely used as the initial imaging study. Supporting Documents The evidence table, literature search, and appendix for this topic are available at https://acsearch. acr.org/list. The appendix includes the strength of evidence assessment and the final rating round tabulations for each recommendation.


Right Lower Quadrant Pain

Right Lower Quadrant Pain.  Introduction/Background Right lower quadrant (RLQ) abdominal pain accounts for nearly 50% of patients presenting to the emergency department with abdominal pain [1]. Appendicitis is the most common surgical pathology responsible for RLQ abdominal pain in the United States [1,2]. Other less frequent causes of RLQ pain include right colonic diverticulitis, ureteral stone, colitis, and intestinal obstruction [1,3,4]. Imaging remains the diagnostic mainstay in the workup of patients presenting with RLQ abdominal pain for evaluation of suspected appendicitis and diagnosis of other conditions. Buckius et al [2] reported an annual increase in the rate of acute appendicitis in the United States; however, Ferris et al [5], in a recent systematic review of population-based studies, showed that although the incidence of both perforated and nonperforated appendicitis is stable in North America, the incidence is rising in newly industrialized countries. Historically, the clinical determination of appendicitis has been poor, particularly in special patient populations, such as those at the extremes of age and pregnant women. The negative appendectomy rate (NAR) based on clinical determination alone without imaging is unacceptably high, as high as 25% [6]. Clinical decisions tools, such as the Alvarado score (AS), have not improved the outright diagnostic accuracy of the clinical examination [7] and demonstrate mixed results as an adjunct to help guide CT use [8,9]. The decrease in NAR with increased imaging utilization is not accompanied by an increase in perforations from any introduced delays [10,11]. The choice of imaging modality should be tailored for diagnosis of acute appendicitis in patients with a high degree of suspicion but should also allow diagnosis of other causes of RLQ pain to triage appropriate patient management.


Chronic Hip Pain PCAs

Chronic Hip Pain PCAs.  Introduction/Background Chronic hip pain is a common chief complaint for patients, reportedly affecting 30% to 40% of adults who play sports [1,2], and 12% to 15% of all adults over 60 [3,4]. A wide variety of pathological entities may cause hip pain, including osseous as well as intra- or extra-articular soft tissue abnormalities [5-7]. Pathology involving the lumbar spine, sacroiliac, or knee joints can also cause hip pain [8], and these etiologies should be investigated as needed. There is limited original research that specifically targets the imaging of chronic hip pain, but imaging of specific conditions is widely discussed in the published literature. OR The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through representation of such organizations on expert panels. Participation on the expert panel does not necessarily imply endorsement of the final document by individual contributors or their respective organization. Reprint requests to: publications@acr.org Chronic Hip Pain Discussion of Procedures by Variant Variant 1: Chronic hip pain. Initial Imaging. Bone Scan Hip There is no relevant literature to support the use of bone scan of the hip in the initial evaluation of chronic hip pain. CT Arthrography Hip There is no relevant literature to support the use of CT arthrography of the hip in the initial evaluation of chronic hip pain. CT Hip With IV Contrast There is no relevant literature to support the use of CT hip with intravenous (IV) contrast in the initial evaluation of chronic hip pain. CT Hip Without and With IV Contrast There is no relevant literature to support the use of CT hip without and with IV contrast in the initial evaluation of chronic hip pain. CT Hip Without IV Contrast There is no relevant literature to support the use of CT of the hip without IV contrast in the initial evaluation of chronic hip pain.


Chronic Hip Pain PCAs

Chronic Hip Pain PCAs. Fluoride PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of fluoride PET/CT skull base to mid-thigh in the initial evaluation of chronic hip pain. Image-Guided Anesthetic +/- Corticosteroid Injection Hip Joint or Surrounding Structures There is no relevant literature to support the use of image-guided anesthetic +/- corticosteroid injection hip joint or surrounding structures in the initial evaluation of chronic hip pain. MR Arthrography Hip There is no relevant literature to support the use of MR arthrography of the hip in the initial evaluation of chronic hip pain. MRI Hip Without and With IV Contrast There is no relevant literature to support the use of MRI of the hip without and with IV contrast in the initial evaluation of chronic hip pain. MRI Hip Without IV Contrast There is no relevant literature to support the use of MRI of the hip without IV contrast in the initial evaluation of chronic hip pain. Radiography Hip The literature indicates that radiography is a first-line screening tool, and hip radiographs are useful in the initial imaging workup of chronic hip pain [12]. Oftentimes a pelvic radiograph, which includes imaging of both hips, may be obtained concurrently with additional dedicated collimated radiograph(s) of the affected hip(s). Findings on hip radiographs can result in an imaging diagnosis such as osteoarthritis or can lead to more advanced workups of less common causes of chronic hip pain such as primary bone tumors. The results of screening hip radiographs can help guide the use of additional imaging studies such as more specialized radiographic views or more advanced modalities such as CT, ultrasound (US), MRI, radionuclide bone scans, and fluoride PET [13-15]. Radiography Pelvis The literature indicates that radiography is a first-line screening tool, and pelvic radiographs are useful in the initial imaging workup of chronic hip pain [12].


Chronic Hip Pain PCAs

Chronic Hip Pain PCAs. A pelvic radiograph is an excellent initial examination because it allows for evaluation of both hip joints on a single radiographic image, allowing for comparison of the ipsilateral and contralateral hips. Oftentimes, a pelvic radiograph may be obtained concurrently with additional dedicated radiograph(s) of the affected hip. Findings on pelvic radiographs can result in an imaging diagnosis such as osteoarthritis or may lead to more advanced workups of less common causes of chronic hip pain such as primary bone tumors. The results of the pelvic radiograph can help the clinician for the selection of additional imaging techniques and for comparison with studies such as MRI, CT, radionuclide bone scans, and fluoride PET [13-15]. Chronic Hip Pain US Hip There is no relevant literature to support the use of US hip in the initial evaluation of chronic hip pain. Variant 2: Chronic hip pain. Suspect noninfectious extra-articular abnormality, such as tendonitis or bursitis. Radiographs negative or nondiagnostic. Next imaging study. Bone Scan Hip There is no relevant literature to support the use of bone scan of the hip in the evaluation of extra-articular soft tissue abnormalities. CT Arthrography Hip The instillation of intra-articular contrast may elucidate periarticular soft tissue abnormalities such as labral or capsular pathology [16-18]. However, CT arthrography is limited for evaluating the extra-articular soft tissue pathology because of the inherent poor soft tissue contrast of CT. Within the limitation of CT; however, some extra- articular pathologic entities, such as a large, distended bursa may be evident on CT. Tendinous pathology is not particularly well depicted on CT. CT Hip With IV Contrast There is no relevant literature to support the use of CT hip with IV contrast in the evaluation of tendon or bursal pathology.


Chronic Hip Pain PCAs

Chronic Hip Pain PCAs. CT Hip Without and With IV Contrast There is no relevant literature to support the use of CT hip without and with IV contrast in the evaluation of tendon or bursal pathology. CT Hip Without IV Contrast CT hip without IV contrast is of limited use in the evaluation of extra-articular soft tissue pathology because of the inherent poor soft tissue contrast of CT [18]. Within the limitation of the contrast resolution of CT, some extra- articular pathologic entities, such as a large, distended bursa may be evident on CT. Tendinous pathology is not well evaluated on CT. Fluoride PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of fluoride PET/CT skull base to mid-thigh in the evaluation of chronic hip pain thought to be due to a noninfectious extra-articular abnormality. MR Arthrography Hip There is no relevant literature to support the use of MR arthrography in the evaluation of extra-articular soft tissue pathology. MRI Hip Without and With IV Contrast There is no relevant literature to support administration of IV contrast (gadolinium chelate agents) for routine MRI of the hip. MRI Hip Without IV Contrast MRI without IV contrast is useful for evaluating soft tissues given its high soft tissue contrast resolution [23]. Numerous studies have demonstrated that MRI is both highly sensitive and specific for evaluation of the articular and periarticular soft tissues [24]. As such, noncontrast MRI should be considered as the next imaging test following radiographic evaluation of the hip joint [25-34]. Trochanteric, iliopsoas, ischial, and subiliacus bursitis are well demonstrated on noncontrast MRI, as are abductor and adductor tendinosis and tears, hamstring injuries, athletic pubalgia, and calcific tendinosis. Large field-of-view images obtained as part of a hip MRI can also sometimes Chronic Hip Pain US Hip The literature indicates that US is useful for the evaluation of extra-articular soft tissues in the region of the hip [23].


Chronic Hip Pain PCAs

Chronic Hip Pain PCAs. US can also nicely demonstrate fluid collections around the hip, such as bursitis and paralabral cysts. Tendon pathology, such as tendinosis, tears, or snapping iliopsoas tendons can also be identified with US [38-41]. US may also be useful for the dynamic evaluation of the iliopsoas tendon, such as in snapping hip syndrome. Variant 3: Chronic hip pain. Suspect impingement or dysplasia. Radiographs negative or nondiagnostic. Next imaging study. Bone Scan Hip There is no relevant literature to support to the use of bone scan of the hip in the evaluation of suspected hip impingement. CT Arthrography Hip Pathology associated with femoracetabular impingement (FAI) may be both intra- and extra-articular. CT is often used for preoperative assessment of bony anatomy in the setting of FAI and hip dysplasia [42-44]. CT arthrography has been shown to be sensitive for detection of acetabular labral tears [17], which may be associated with FAI. CT arthrography has also been shown to be more helpful in identifying chondral lesions [16] when compared to MRI. However, arthrography does not offer an advantage over noncontrast CT for the detection of extra-articular impingement (eg, ischiopelvic, ischiotrochanteric, subspinous, and femoropelvic). CT Hip With IV Contrast CT without IV contrast is often used for preoperative assessment of bony anatomy in the setting of FAI and hip dysplasia [42-44]. However, IV contrast administration does not confer an additional advantage for evaluation of hip impingement. CT Hip Without and With IV Contrast Noncontrast CT is often used for preoperative assessment of bony anatomy in the setting of FAI and hip dysplasia [42-44]. IV contrast administration is not warranted for evaluation of hip impingement. Fluoride PET/CT Skull Base to Mid-Thigh One study demonstrated the potential use of fluoride PET to demonstrate increased bone turnover in the setting of chronic hip pain and FAI [50].


Chronic Hip Pain PCAs

Chronic Hip Pain PCAs. One other study demonstrated that fluoride PET can demonstrate acetabular contrecoup injuries in patients with FAI [51]. However, increased radiotracer uptake is a nonspecific finding, and, overall, there is insufficient literature to support the use of fluoride PET/CT skull base to mid-thigh in the evaluation of chronic hip pain thought to be due to hip impingement and/or dysplasia. Chronic Hip Pain MR Arthrography Hip Direct MR arthrography, performed following the intra-articular injection of a 1:200 solution of gadolinium chelate in saline, is useful for diagnosing acetabular labral tears [65-70] that are frequently associated with FAI [71,72] and/or hip dysplasia. MR arthrography has been shown to have a sensitivity of 94.5% and a specificity of 100% for the detection of labral tears [52], which may be associated with FAI. Some authors have shown that MRI without IV contrast and MR arthrography are similarly accurate and sensitive for detecting labral tears in the setting of FAI [53], and other authors have shown that MR arthrography is superior to conventional MRI [54,55]. Several publications show that MR arthrography is superior to CT arthrography and noncontrast MRI for evaluation of labral tears [18,56], but there are other publications that demonstrate that CT arthrography and noncontrast MRI are superior [16,57-59]. MR arthrography may also nicely demonstrate acetabular chondral delamination [60]. Although MR arthrography can be useful for demonstrating labral and chondral pathology associated with impingement, the presence of intra-articular contrast offers no advantage over noncontrast MRI for the detection of extra-articular abnormalities associated with impingement. MRI Hip Without and With IV Contrast Indirect arthrography is a technique that falls under the category of MRI hip with contrast. When administered intravenously, gadolinium chelate contrast can diffuse into the joint space via the synovium, and this results in indirect arthrography.


Chronic Hip Pain PCAs

Chronic Hip Pain PCAs. There is limited literature supporting the use of indirect arthrography instead of direct MR arthrography for evaluating intra-articular disorders [34,61-63]. IV, rather than intra-articular, injection of contrast is faster and easier to perform and does not require image guidance, but indirect arthrography does not distend the joint capsule and results in less consistent enhancement of the joint space. The accuracy of indirect arthrography for evaluation of the acetabular labrum and articular cartilage remains uncertain. Because the literature supporting indirect arthrography is scant, it is a technique that is not often used clinically. MRI without IV contrast is useful for evaluating the labrum and articular cartilage in the setting of FAI and/or dysplasia. It can even be used for the detailed assessment of osseous anatomy, such as the shape and contour of the femoral neck. A noncontrast MRI can demonstrate findings of extra-articular impingement as well. At times, indirect arthrography may be performed following noncontrast image acquisition in order to obtain a complementary assessment of the hip and its synovium. MRI Hip Without IV Contrast FAI and dysplasia are associated with both intra- and extra-articular abnormalities, both osseous and soft tissue. The literature demonstrates that a noncontrast MRI is useful in the assessment of labral and cartilage lesions in the setting of hip impingement. Investigators have demonstrated success in detecting labral and articular cartilage lesions with high-resolution MRI of the hip at 1.5T without intra-articular contrast [58,68]. Additional literature has shown that high-resolution 3T MRI without IV contrast can further improve the visualization of the acetabular labrum and the articular cartilage of the femoral head and acetabulum [69,70]. Evaluation of cortical bone is more difficult with conventional MRI than it is with CT, but the use of isotropic MR sequences has been shown to be effective in the evaluation of FAI [71].


Chronic Hip Pain PCAs

Chronic Hip Pain PCAs. Some centers routinely evaluate the shape and contours of the femoral neck by utilizing radial imaging or radial reconstructions. Additional research has shown that the zero-echo time pulse sequence offers excellent visualization of cortical bone on MRI without the need for contrast, and it has been shown to be an effective sequence for evaluating osseous hip morphology [72]. MRI can also be useful in detecting extra-articular impingements (ischiopelvic, ischiotrochanteric, subspinous, and femoropelvic) [45,46]. Although there is a paucity of supportive data, some surgeons may use both MRI and CT in order to define the soft tissues (labrum and articular cartilage) and the bone, respectively. Measurements can be performed on radiography, CT, and MRI [42-44,47,48]. Chronic Hip Pain Radiography Hip Additional Views For further evaluation of disorders such as dysplasia or FAI, specialized views such as the false profile or elongated femoral neck lateral (Dunn) views can provide more detailed evaluation of the anatomy of the femoral head and neck and the degree of acetabular coverage of the femoral head [47]. US Hip In general, US is limited in its use for evaluating osseous structures. However, there is limited literature that demonstrates that US can be used to evaluate osseous features of FAI such as the alpha-angle [73]. However, US is not able to adequately evaluate osseous abnormalities deep to the cortex. One of the advantages of US is its ability to dynamically evaluate for extra-articular soft tissue impingement. US is not as sensitive as MRI or CT arthrography for the detection of labral tears [17], but it can be useful for the detection and localization of paralabral cysts for aspiration and injection [39,41]. Variant 4: Chronic hip pain. Suspect labral tear. Radiographs negative or nondiagnostic. Next imaging study. Bone Scan Hip There is no relevant literature to support the use of bone scan of the hip for the workup of an acetabular labral tear in a patient with chronic hip pain.


Chronic Hip Pain PCAs

Chronic Hip Pain PCAs. CT Arthrography Hip Some authors have shown that CT arthrography can be useful in the detection of acetabular labral tears [17,74], which may be associated with FAI, but other authors have shown that CT arthrography is not very good for the detection of labral tears [18]. CT Hip With IV Contrast There is no relevant literature to support the use of CT hip with IV contrast for the workup of an acetabular labral tear in a patient with chronic hip pain. CT Hip Without and With IV Contrast There is no relevant literature to support the use of CT hip without and with IV contrast for the workup of an acetabular labral tear in a patient with chronic hip pain. CT Hip Without IV Contrast Because of its inherent poor contrast resolution, there is no relevant literature supporting the use of CT hip without IV contrast for the workup of an acetabular labral tear in a patient with chronic hip pain. Fluoride PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of fluoride PET/CT skull base to mid-thigh in the evaluation of chronic hip pain thought to be due to a labral tear. Image-Guided Anesthetic +/- Corticosteroid Injection Hip Joint or Surrounding Structures Diagnostic joint injections are safe and useful tools for confirming the etiology of pain, such as a labral tear or symptomatic paralabral cyst [20-22]. MR Arthrography Hip Direct MR arthrography, with the intraarticular injection of a 1:200 solution of gadolinium chelate in saline, has been established as a reliable technique for diagnosing acetabular labral tears [75-80] that are frequently associated with FAI [81,82]. MR arthrography has been shown to have a sensitivity of 94.5% and a specificity of 100% for the detection of labral tears [52]. Within some of the published literature, MR arthrography has often been demonstrated to be superior to CT arthrography and noncontrast MRI for evaluation of labral tears [18,56]. However, in other articles, CT arthrography and noncontrast MRI fare better [16,57-59].


Chronic Hip Pain PCAs

Chronic Hip Pain PCAs. MRI Hip Without and With IV Contrast Indirect arthrography is a technique that falls under the category of MRI hip with contrast. For performance of indirect MR arthrography, gadolinium chelate contrast is administered by IV injection and diffuses into the joint space through the synovium. This technique has been proposed as an alternative to direct MR arthrography for detecting intra-articular disorders [34,61-63] because it is faster and easier to perform than direct arthrography and does not require image guidance. However, indirect arthrography offers less consistent enhancement of the joint space and cannot distend the joint capsule. Although the literature is scant, there are a few small studies suggesting Chronic Hip Pain that indirect MR arthrography may be helpful in detecting labral pathology [83,84]. However, as the literature supporting indirect arthrography is very limited, it is a technique that is not often used clinically. MRI Hip Without IV Contrast MRI is currently the reference standard for evaluation of labral pathology [85]. For evaluating labral tears, MRI with or without arthrography can be used [76-79]. Several investigators suggest that high-resolution 3T MRI may improve the visualization of the acetabular labrum and the hyaline articular cartilage [69,70], which may obviate the need for intra-articular contrast [86]. Other investigators have obtained satisfactory results in detecting labral and hyaline cartilage lesions with high-resolution MRI of the hip at 1.5T without intra-articular contrast [58,68]. US Hip Although not as commonly used as MRI for the detection of labral pathology, US has been able to document the presence of labral tears in patients with hip pain [87,88]. However, it is not as sensitive as other modalities for detecting labral tears [17]. US can also be used to localize paralabral cysts for aspiration and injection [39,41]. Variant 5: Chronic hip pain. Radiographs equivocal or positive for mild osteoarthritis.


Chronic Hip Pain PCAs

Chronic Hip Pain PCAs. Evaluate articular cartilage integrity. Next imaging study. Bone Scan Hip There is no relevant literature to support the use of bone scan of the hip in the assessment of the extent of cartilage damage in a patient with chronic hip pain. CT Arthrography Hip Direct visualization of articular cartilage is possible using those imaging techniques that provide either intrinsic contrast (MRI and US) or extrinsic contrast (any type of arthrography) [89]. Hip cartilage abnormalities can be successfully evaluated by high-resolution CT arthrography [18,90-93], thus allowing for improved assessment of the degree of cartilage loss when compared with the initial radiographs. CT Hip With IV Contrast Because of its inherent poor soft tissue contrast resolution, there is no relevant literature to support the use of CT hip with IV contrast in the assessment of the extent of cartilage damage in a patient with chronic hip pain. CT Hip Without and With IV Contrast Because of its inherent poor soft tissue contrast resolution, there is no relevant literature to support the use of CT hip without and with IV contrast in the assessment of the extent of cartilage damage in a patient with chronic hip pain. CT Hip Without IV Contrast Because of its inherent poor soft tissue contrast resolution, there is no relevant literature to support the use of CT hip without IV contrast in the assessment of the extent of cartilage damage in a patient with chronic hip pain. Fluoride PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of fluoride PET/CT skull base to mid-thigh in the assessment of the extent of cartilage damage in a patient with chronic hip pain. Image-Guided Anesthetic +/- Corticosteroid Injection Hip Joint or Surrounding Structures Although image-guided anesthetic and/or corticosteroid injections may be useful in the diagnosis and treatment of patients with osteoarthritis, it does not offer the possibility of evaluating the extent of cartilage damage that may exist in a joint.


Chronic Hip Pain PCAs

Chronic Hip Pain PCAs. Image-guided therapeutic injections have not been shown to alter patient reported outcome measures [94]. MR Arthrography Hip Direct visualization of articular cartilage is possible on MRI because of its intrinsic excellent soft tissue contrast resolution. Intra-articular administration of contrast can also help with the direct visualization of articular cartilage [89]. MR arthrography has been shown to have high sensitivity and fair specificity of 92.5% and 54.5%, respectively, for the detection of chondral pathology in the setting of FAI [52]. A lower sensitivity for the detection of chondral pathology has been reported for the detection of hip articular cartilage defects in a more generalized group of patients [55]. Assessment of the T2* relaxation time is not affected by the presence of intra-articular gadolinium injection [95], and, although more commonly used for research purposes, T2* may be used to assess cartilage ultrastructure. Chronic Hip Pain MRI Hip Without and With IV Contrast Indirect arthrography falls under the technique of MRI hip with IV contrast. The diagnostic accuracy of indirect MR arthrography has not been widely studied [96], and, as such, there is insufficient literature to support the use of MRI with IV contrast in assessment for the degree of cartilage damage. IV contrast administration can; however, help to demonstrate the degree of enhancing inflamed synovium. Delayed gadolinium-enhanced MRI of cartilage may be useful in assessing the degree of hip cartilage damage, but this is most frequently employed in the research setting [97]. Overall, given the scant literature supporting indirect arthrography, this is a technique that is not often used clinically. MRI Hip Without IV Contrast Direct visualization of articular cartilage is possible on MRI because of its intrinsic excellent soft tissue contrast resolution [89]. MRI can demonstrate the articular cartilage and areas of chondral pathology [18,91,93].


Chronic Hip Pain PCAs

Chronic Hip Pain PCAs. MRI has been shown to be 85.92% accurate for identification of acetabular chondral rim lesions when compared to arthroscopy [85]. Various MRI techniques such as T2 mapping, T1rho, and sodium imaging allow for the ultrastructural assessment of articular cartilage [98]. Although these techniques are primarily used in the research setting, some have also been applied in the routine evaluation of clinical patients. US Hip US is limited in the hip by its inability to evaluate the acetabular or the majority of the femoral head cartilage. The acoustic window to see articular cartilage in the hip is limited. Variant 6: Chronic hip pain. Radiographs suspicious for intra-articular synovial hyperplasia or neoplasia including nodular synovitis, diffuse tenosynovial giant cell tumor, osteochondromatosis, other synovial neoplasm. Next imaging study. Image-Guided Aspiration Hip Image-guided aspiration/injections demonstrate brown or bloody aspirate in patients with the diffuse form of tenosynovial giant cell tumor [99,100]. The diagnosis of synovial hyperplasia/neoplasia may require a tissue sample. Bone Scan Hip There is no relevant literature to support the use of bone scan of the hip in the assessment of the intra-articular synovial hyperplasia/neoplasia in a patient with chronic hip pain. CT Arthrography Hip CT arthrography may be helpful in evaluating whether there are intra-articular bodies or hypertrophic synovium. CT Hip With IV Contrast There is no relevant literature to support the use of CT hip with IV contrast for the workup of synovial hyperplasia/neoplasia in a patient with chronic hip pain. CT Hip Without and With IV Contrast It can be quite difficult to distinguish diffuse tenosynovial giant cell tumor from synovial chondromatosis and other proliferative synovial processes on imaging. CT without IV contrast might help to detect calcification. However, there is no added benefit of administering IV contrast for the diagnosis of a synovial proliferative process.


Chronic Hip Pain PCAs

Chronic Hip Pain PCAs. CT Hip Without IV Contrast Intra-articular sources of pain such as synovitis, whether inflammatory (eg, Lyme disease), proliferative (eg, synovial chondromatosis), or neoplastic (eg, chondroma), are well demonstrated on MRI. It can be quite difficult to distinguish tenosynovial giant cell tumor from synovial chondromatosis and other proliferative synovial processes, although CT might help to detect subtle calcifications, which can sometimes be seen with synovial chondromatosis but are not typically seen in the setting of tenosynovial giant cell tumor. Fluoride PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of fluoride PET/CT skull base to mid-thigh in the assessment of the intra-articular synovial hyperplasia/neoplasia in a patient with chronic hip pain. Image-Guided Anesthetic +/- Corticosteroid Injection Hip Joint or Surrounding Structures There is no relevant literature to support the use of image-guided anesthetic +/- corticosteroid injection hip joint or surrounding structures in the assessment of the intra-articular synovial hyperplasia/neoplasia in a patient with chronic hip pain. Chronic Hip Pain MR Arthrography Hip Instillation of intra-articular contrast may be helpful in elucidating whether a body/bodies are intra-articular. However, in cases in which precise intra-articular pathology is still unknown and neoplasm remains a consideration, histologic sampling of the neoplastic process is probably indicated before instillation of contrast into the joint to avoid unintended harm. MRI Hip Without and With IV Contrast MRI hip with IV contrast administration may be helpful in distinguishing enhancing inflamed synovium from a bland joint effusion. MRI Hip Without IV Contrast Intra-articular sources of pain such as synovitis, whether inflammatory (eg, Lyme disease), proliferative (eg, synovial chondromatosis), or neoplastic (eg, chondroma), are well demonstrated on MRI.


Chronic Hip Pain PCAs

Chronic Hip Pain PCAs. It can be quite difficult to distinguish tenosynovial giant cell tumor from synovial chondromatosis and other proliferative synovial processes. MRI, including a gradient-echo sequence, may be useful in assessing for blooming, which would indicate the presence of hemosiderin, such as can be seen in tenosynovial giant cell tumor. US Hip There is no relevant literature to support the use of diagnostic US hip in the assessment of the intra-articular synovial hyperplasia/neoplasia in a patient with chronic hip pain. Variant 7: Chronic hip pain with low back or knee pathology or pain. Radiographs demonstrate hip osteoarthritis. Want to quantify amount of pain related to the hip. Next imaging study. Bone Scan Hip Although a bone scan of the hip may be able to demonstrate pathology about the hip, it cannot be used to quantify the amount pain that is generated from the hip pathology. CT Hip With IV Contrast Although CT hip with IV contrast may be able to demonstrate pathology about the hip, it cannot be used to quantify the amount pain that is generated from the hip pathology. CT Hip Without and With IV Contrast Although CT hip without and with IV contrast may be able to demonstrate pathology about the hip, it cannot be used to quantify the amount pain that is generated from the hip pathology. CT Hip Without IV Contrast Although CT hip without IV contrast may be able to demonstrate pathology about the hip, it cannot be used to quantify the amount pain that is generated from the hip pathology. Fluoride PET/CT Skull Base to Mid-Thigh Although fluoride PET/CT skull base to mid-thigh may be able to demonstrate pathology about the hip, knee, and spine, it cannot be used to quantify the amount pain that is generated from the hip pathology. MR Arthrography Hip Although MR arthrography hip may be able to demonstrate pathology about the hip, it cannot be used to quantify the amount pain that is generated from the hip pathology. If anesthetic is mixed with the contrast that is injected Chronic Hip Pain


Ataxia Child

Ataxia Child.  Specific manifestations of ataxia may correspond to certain causes or may be discovered by particular triggers. For example, truncal ataxia is typical of cerebellar vermian pathology [1]. A lurching gait, when triggered by head rotation, is typical of vestibular dysfunction [9]. Sensory ataxia can be revealed by a positive Romberg test, which examines the dorsal columns. [9]. Additionally, ataxia with specific signs can suggest the underlying disorder. Pupillary abnormalities may suggest drug or toxin ingestion versus third cranial nerve compression. Torticollis or resistance to head and neck motion may indicate pathology at the craniocervical junction, cord compression, or posterior fossa tumor [9]. Based on a systematic review of European data, the estimated prevalence of childhood ataxia due to genetic and acquired causes is approximately 26 per 100,000 children, although the true worldwide prevalence may be higher [10]. Regional variations exist in the prevalence of childhood ataxia, with a higher prevalence of genetic causes of ataxia in countries with high consanguinity, and a higher prevalence of infectious causes such as malaria and varicella in other regions where these diseases are more common [10]. Evaluation of ataxia requires careful review of demographics, history (especially duration of symptoms and the presence of additional neurological deficits), clinical examination, laboratory testing, and neuroimaging to reach a cohesive diagnosis [2,7,11-13]. In young children and infants, a detailed neurological examination is often challenging, and initial imaging therefore plays a critical role in arriving at a diagnosis. The time course of illness (eg, acute, recurrent, chronic with or without progression) may indicate or rule out potential etiology. Acute onset ataxia typically refers to ataxia that develops within hours or days and frequently presents within 72 hours, whereas chronic ataxia is defined as ataxia lasting longer than 2 months [1,14].


Ataxia Child

Ataxia Child. Acutely presenting ataxia in children may be due to infectious, inflammatory, toxic, ischemic, or traumatic etiology. Intermittent or episodic ataxia in children may be manifestations of migraine, benign positional vertigo, or intermittent metabolic disorders. Whereas nonprogressive childhood ataxia suggests a congenital brain malformation or early prenatal or perinatal brain injury, progressive childhood ataxia may be due to inherited causes or acquired posterior fossa lesions that result in gradual cerebellar dysfunction. Reprint requests to: publications@acr.org Although MIBG (iodine-123 meta-iodobenzylguanidine) and CT imaging of the chest, abdomen, and pelvis is used in specific workup of children presenting with opsoclonus-myoclonus-ataxia syndrome, for diagnosing underlying neuroblastoma or ganglioneuroblastoma, they may not typically be the first line of imaging. It should be noted that opsoclonus-myoclonus-ataxia syndrome is one of the less common presentations of tumors such as neuroblastoma or ganglioneuroblastoma. A complete description of signs and symptoms of neuroblastoma or ganglioneuroblastoma and their workup are beyond the scope of this document. Ataxia-Child Cerebellar stroke is a rare cause of acute ataxia in children, with one series identifying 3 cases out of 364 children presenting to the emergency department with acute ataxia [26]. Despite its rarity, diagnosing acute cerebellar infarct is critical because of implications for appropriate diagnostic workup and management. Collective assessment of several studies suggests that, although acute imaging may reveal a clinically urgent condition [1,7,21,22,25-27], the yield of clinically significant findings may be highest in children >3 years of age with symptoms for >3 days duration and in the presence of extracerebellar symptoms, such as somnolence, encephalopathy, focal motor weakness, or cranial nerve involvement [13,18,20,26].


Ataxia Child

Ataxia Child. In young children presenting with acute cerebellar ataxia and a recent history of viral illness but without extracerebellar neurologic signs and symptoms and a negative urine drug screen, watchful waiting has been suggested [18], with imaging reserved for those with clinical deterioration. Therefore, the need for neuroimaging in the acute setting should be guided by the clinical presentation, history, and laboratory testing. CT Head In a large study assessing imaging in 104 children presenting with acute or subacute ataxia, CT abnormalities were identified in up to 29% of children [20]. Clinically significant findings have been identified on CT in 7% of children presenting with acute ataxia [18]. Although the study by Whelan et al [13] only showed significant intracranial abnormalities on CT in 2.5% of the children presenting with acute ataxia, their study was limited by the fact that only a small proportion of children had imaging. In the absence of preceding trauma, CT is useful in identifying nontraumatic acute intracranial hemorrhage but can also identify hydrocephalus, cerebellar edema, and calcifications [7,28]. However, CT is less sensitive than MRI in displaying intracranial pathology including posterior fossa abnormalities [20,26]. There is no relevant literature to support the use of contrast-enhanced head CT in the evaluation of acute childhood ataxia. CT Complete Spine There is no relevant literature to support the use of CT complete spine in the initial evaluation of a child with acute ataxia and no history of recent trauma. CTA Head and Neck CT angiography (CTA) of the head and neck may be helpful in children with ataxia due to a posterior circulation stroke, hemorrhage, or vascular malformation. However, this investigation may need to be decided based on the clinical presentation and concern for acute cerebellar infarct [7]. Stroke or vascular malformations are the etiology in only 1% to 3% of acute childhood ataxia [20,26].


Ataxia Child

Ataxia Child. Although there is no relevant literature distinguishing between CTA of head and neck versus CTA of either the head or neck alone in these rare vascular causes of acute childhood ataxia, CTA of the head and neck may be more beneficial than either CTA head or CTA neck alone because the site of vascular abnormality may be in either the head or the neck or both locations. Ataxia-Child CTA Head CTA of the head in conjunction with CTA of the neck may be helpful in children with ataxia due to a posterior circulation stroke, hemorrhage, or a vascular malformation. However, this investigation may need to be decided based on the clinical presentation and concern for acute cerebellar infarct [7]. Stroke or vascular malformations are the etiology in only 1% to 3% of acute childhood ataxia [20,26]. CTA Neck CTA of the neck, in conjunction with CTA of the head, may be helpful in children with ataxia due to a posterior circulation stroke, hemorrhage, or a vascular malformation. However, this investigation may need to be decided based on the clinical presentation and concern for acute cerebellar infarct [7]. Stroke or vascular malformations are the etiology in only 1% to 3% of acute childhood ataxia [20,26]. CTV Head There is no relevant literature to support the use of CT venography (CTV) head in the initial evaluation of a child with acute ataxia and no history of recent trauma. MRI Head In a study of 104 children imaged for acute or subacute ataxia, MRI abnormalities were identified in 64% of the cases [20]. However, clinically significant intracranial abnormalities on MRI have been reported in 14% of children presenting with acute or subacute ataxia [18,20]. MRI is more sensitive than CT in the evaluation of intracranial pathology in acute ataxia in children [20]. In a study by Luetje at al [20], abnormalities were identified on MRI but not on CT in 8 children.


Ataxia Child

Ataxia Child. Intravenous (IV) contrast is helpful in infectious and postinfectious disorders, demyelinating conditions, and brain tumors, which are the common causes of acute cerebellar ataxia in children [19]. MRI Complete Spine MRI of the spine may be helpful in children with ataxia due to causes such as acute disseminated encephalomyelitis, brain tumors, and demyelinating disease, all of which may show additional abnormalities of the spinal cord [29]. Generally, if there is a high clinical suspicion for a condition that may have spinal cord or paravertebral abnormalities, MRI of the spine can be included when imaging the neuroaxis. Although there is no relevant literature discussing the specific use of contrast in MRI of the spine in acute childhood ataxia, addition of postcontrast imaging may be useful in assessing neoplastic, demyelinating, and inflammatory lesions, which are common causes of acute cerebellar ataxia in children [20]. MR Spectroscopy Head There is no relevant literature to support the use of MR spectroscopy head in the initial evaluation of a child with acute ataxia and no history of recent trauma. MRA Head and Neck MR angiography (MRA) of the head and neck may be a helpful tool in assessing ataxia due to a posterior circulation stroke, hemorrhage, or vascular malformation. However, a posterior circulation stroke is rare in children, and this investigation may need to be decided based on the clinical presentation and concern for acute cerebellar infarct [7]. Stroke or vascular malformations may present with ataxia in 1% to 3% of cases [20,26]. Although there is no relevant literature distinguishing between MRA of head and neck versus MRA of either the head or MRA neck alone in these rare vascular causes of acute childhood ataxia, MRA of the head and neck may be more beneficial than either MRA head or neck alone because the site of vascular abnormality may be in either the head or neck or both locations.


Ataxia Child

Ataxia Child. MRA Head MRA of the head in conjunction with MRA of the neck may be a helpful tool in assessing ataxia due to posterior circulation stroke, hemorrhage, or vascular malformation. However, a posterior circulation stroke is rare in children, and this investigation may need to be decided based on the clinical presentation and concern for acute cerebellar infarct [7]. Stroke or vascular malformations may present with ataxia in 1% to 3% of cases [20,26]. MRA Neck MRA of the neck in conjunction with MRA of the head may be a helpful tool in assessing ataxia due to posterior circulation stroke, hemorrhage, or vascular malformation. However, a posterior circulation stroke is rare in children, and this investigation may need to be decided based on the clinical presentation and concern for acute cerebellar infarct [7]. Stroke or vascular malformations may present with ataxia in 1% to 3% of cases [20,26]. Ataxia-Child MRV Head and Neck There is no relevant literature to support the use of MR venography (MRV) head and neck in the initial evaluation of a child with acute ataxia and no history of recent trauma. MRV Head There is no relevant literature to support the use of MRV head in the initial evaluation of a child with acute ataxia and no history of recent trauma. MIBG Scan In a child presenting with acute opsoclonus-myoclonus-ataxia syndrome, an MIBG scan may be helpful in the workup for identifying neuroblastoma, ganglioneuroblastoma, or ganglioneuroma as the causative etiology [2,13]. In the absence of any relevant literature, an MIBG scan may not be beneficial as a first-line imaging test in a child presenting with acute ataxia. CT Chest, Abdomen, and Pelvis In a child presenting with acute opsoclonus-myoclonus-ataxia syndrome with concern for neuroblastoma or ganglioneuroblastoma or ganglioneuroma, initial imaging with CT of the chest, abdomen, and pelvis with IV contrast may be helpful for diagnosis, although the clinical utility of CT as an initial imaging modality is less clear [2,13].


Ataxia Child

Ataxia Child. MRI Chest, Abdomen, and Pelvis In a child presenting with acute opsoclonus-myoclonus-ataxia syndrome, with clinical suspicion for neuroblastoma, ganglioneuroblastoma, or ganglioneuroma, MRI of the chest, abdomen, and pelvis without and with IV contrast may be helpful to identify the underlying mass [2,13]; however, there is no literature to support the use of this modality as an initial procedure. Variant 2: Child. Acute ataxia, history of recent trauma. Initial imaging. Head trauma is a rare but important cause of ataxia in children, accounting for approximately 5% of acute childhood ataxias [18]. Ataxia after recent head and neck trauma may be due to intracranial hemorrhage, cerebral contusion, concussion, or traumatic vertebral dissection [18,30]. CTA Head and Neck CTA head and neck may be useful in the diagnostic workup of a child presenting with acute ataxia with a recent history of trauma, because of a vertebral artery dissection that may result in a cerebellar stroke and present with ataxia. Although most vertebral artery dissections are extracranial in location, CTA of the head and neck may be more beneficial than either CTA head or CTA neck alone to assess entire extent of vascular injury. CTA Head CTA head in conjunction with CTA of the neck may be useful in the diagnostic workup if there is suspicion of traumatic vascular injury such as vertebral artery dissection that may result in a cerebellar stroke and ataxia. Ataxia-Child Although most vertebral artery dissections are extracranial in location, CTA of the head and neck may be more beneficial than either CTA head or CTA neck alone to assess entire extent of vascular injury. CTA Neck CTA neck in conjunction with CTA of the head may be useful in the diagnostic workup if there is suspicion of cervical trauma resulting in cervical vascular injury such as vertebral artery dissection that may result in a cerebellar stroke and ataxia.


Ataxia Child

Ataxia Child. Although most vertebral artery dissections are extracranial in location, CTA of the head and neck may be more beneficial than either CTA head or CTA neck alone to assess entire extent of vascular injury. CTV Head There is no relevant literature to support the use of CTV head in the initial evaluation of a child with acute ataxia following recent trauma. MR Spectroscopy Head There is no relevant literature to support the use of MR spectroscopy of the head in the initial evaluation of a child with acute ataxia following recent trauma. MRA Head and Neck MRA head and neck may be useful in the diagnostic workup if there is suspicion of traumatic vascular injury such as a vertebral artery dissection that may result in a cerebellar stroke and ataxia. Although most vertebral artery dissections are extracranial in location, MRA of the head and neck may be more beneficial than either MRA head or MRA neck alone to assess entire extent of vascular injury. MRA Head MRA head in conjunction with MRA of the neck may be useful in the diagnostic workup if there is suspicion of traumatic vascular injury such as a vertebral artery dissection that may result in a cerebellar stroke and ataxia. Although most vertebral artery dissections are extracranial in location, MRA of the head and neck may be more beneficial than either MRA head or MRA neck alone to assess entire extent of vascular injury. MRA Neck MRA neck may be useful in the diagnostic workup if there is suspicion of traumatic cervical vascular injury such as a vertebral artery dissection that may result in a cerebellar stroke and ataxia. Although most vertebral artery dissections are extracranial in location, MRA of the head and neck may be more beneficial than either MRA head or MRA neck alone to assess entire extent of vascular injury. MRV Head and Neck There is no relevant literature to support the use of MRV head and neck in the initial evaluation of a child with acute ataxia following recent trauma.


Ataxia Child

Ataxia Child. MRV Head There is no relevant literature to support the use of MRV head in the initial evaluation of a child with acute ataxia following recent trauma. Ataxia-Child intermittent ataxia [34]. Recurrent ataxia in a child may be a manifestation of basilar migraines, benign paroxysmal vertigo, genetic disorders such as autosomal dominant episodic ataxia, and metabolic disorders [1,22,25,27,34,35]. Benign paroxysmal vertigo is typically diagnosed by history, physical examination, and when vestibular testing and neuroimaging are normal. Basilar migraines are typically diagnosed based on clinical symptoms and with normal neuroimaging. Autosomal dominant episodic ataxias are a clinically heterogeneous group (at least 6 types described), with imaging findings such as vermian atrophy described in type 2 episodic ataxia. Inborn errors of metabolism, such as intermittent maple syrup urine disease, pyruvate dehydrogenase deficiency, and Hartnup disease can also present with intermittent ataxia during times of stress or illness [1,36,37]; imaging in these cases may be helpful in identifying and characterizing the underlying neurometabolic disease. Children with rotational occlusion of the vertebral artery, also known as bow hunter syndrome, may present with episodic neurologic symptoms including ataxia [38]; however, this condition is rare enough that it is not a diagnostic target for initial evaluation for a child presenting with recurrent ataxia and interval normal neurology examination. CT Head There is no relevant literature to support the use of head CT in the initial evaluation of a child with recurrent ataxia. CT Complete Spine There is no relevant literature to support the use of CT complete spine in the initial evaluation of a child with recurrent ataxia. CTA Head and Neck There is no relevant literature to support the use of CTA head and neck in the initial evaluation of a child with recurrent ataxia.


Ataxia Child

Ataxia Child. CTA Head There is no relevant literature to support the use of CTA head in the initial evaluation of a child with recurrent ataxia. CTA Neck There is no relevant literature to support the use of CTA neck in the initial evaluation of a child with recurrent ataxia. CTV Head There is no relevant literature to support the use of CTV head in the initial evaluation of a child with recurrent ataxia. MRI Head Although there is inadequate literature regarding the utility of MRI in intermittent or episodic ataxia in childhood, head MRI can be useful in diagnosing metabolic disorders and genetic abnormalities [1,25,34]. Neuroimaging in patients with basilar migraine and childhood benign paroxysmal ataxia is typically normal, and establishing normal neuroimaging supports the diagnosis of these conditions in the appropriate clinical setting [1,25,34]. In these aforementioned causes, there is not enough evidence in the literature to support the use of contrast-enhanced MRI in the initial evaluation of a child with episodic or intermittent ataxia [1,25,34]. MRI Complete Spine There is no relevant literature to support the use of MRI complete spine in the initial evaluation of a child with recurrent ataxia. MR Spectroscopy Head Some episodic ataxias may be due to underlying metabolic disorders, and in specific conditions in which an underlying metabolic disorder is suspected, MR spectroscopy may be useful in investigation. MRA Head and Neck There is no relevant literature to support the use of MRA head and neck in the initial evaluation of a child with recurrent ataxia. MRA Head There is no relevant literature to support the use of MRA head in the initial evaluation of a child with recurrent ataxia. Ataxia-Child MRA Neck There is no relevant literature to support the use of MRA neck in the initial evaluation of a child with episodic or intermittent ataxia. MRV Head and Neck There is no relevant literature to support the use of MRV head and neck in the initial evaluation of a child with recurrent ataxia.