Stephanie A. Bernard

Improved differentiation of benign osteochondromas from secondary chondrosarcomas with standardized measurement of cartilage cap at CT and MR imaging

PURPOSE To validate a technique for reproducible measurement of the osteochondroma cartilage cap with computed tomography (CT) and magnetic resonance (MR) imaging and to reevaluate the correlation of the thickness of the cartilage cap with pathologic findings to improve noninvasive differentiation of benign osteochondromas from secondary chondrosarcomas. MATERIALS AND METHODS The institutional review board approved the study and waived the need for informed consent. HIPAA compliance was maintained. After validation of the measurement technique, 101 pathologically confirmed osteochondromas were retrospectively reviewed. Patient demographic data, histologic diagnosis, and chondrosarcoma grade were recorded. Two musculoskeletal radiologists used a standardized technique to independently measure the thicknesses of the cartilage caps on CT and MR images; these measurements were compared for interobserver agreement. Agreement between measurements with CT and MR imaging was also evaluated, as were the sensitivity and specificity of both modalities for differentiation of osteochondromas from chondrosarcomas. RESULTS Evaluated were 67 benign osteochondromas (from 49 male patients and 18 female patients; mean age, 23.4 years) and 34 secondary chondrosarcomas (from 27 male patients and seven female patients; mean age, 33.2 years). On the basis of the proposed measuring technique, there was 88% interobserver measurement agreement with MR imaging (95% confidence interval [CI]: 80%, 94%) and 93% with CT (95% CI: 84%, 98%). The median difference between measurements of cap thickness at CT and MR imaging was 0 cm (25th and 75th percentiles, -3 mm and 1 mm, respectively). With 2 cm used as a cutoff for distinguishing benign osteochondromas from chondrosarcomas, the sensitivities and specificities were 100% and 98% for MR imaging and 100% and 95% for CT, respectively. CONCLUSION The proposed measuring technique allows accurate and reproducible measurement of cartilage cap thickness with both CT and MR imaging. Cap thickness of 2 cm or greater strongly indicated secondary chondrosarcomas.

ACR Appropriateness Criteria® acute trauma to the knee

More than 500,000 visits to the emergency room occur annually in the United States, for acute knee trauma. Many of these are twisting injuries in young patients who can walk and bear weight, and emergent radiographs are not required. Several clinical decision rules have been devised that can considerably reduce the number of radiographs ordered without missing a clinically significant fracture. Although a fracture is seen on only 5% of emergency department knee radiographs, 86% of knee fractures result from blunt trauma. In patients with a fall or twisting injury who have focal tenderness, effusion, or inability to bear weight, radiographs should be the first imaging study obtained. If the radiograph shows no fracture, MRI is best for evaluating for a suspected meniscus or ligament tear, or the injuries from a reduced patellar dislocation. Patients with a knee dislocation should undergo radiographs and an MRI, as well as an angiographic study such as a fluoroscopic, CT, or MR angiogram. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every three years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures, by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Femoroacetabular Impingement: Screening and Definitive Imaging

Femoroacetabular impingement (FAI) is a recently described entity that occurs when there is impaction of the femoralheadorneckonthelabrumandacetabularrimofthe pelvis secondary to either acquired or developmental abnormality of the femoral head and or acetabulum. 1,2 This abnormal osseous morphology leads to chronic impaction at the extremes of range of motion and subsequent damage of the labrum and articular cartilage. It is critical for the radiologist to have a thorough understanding of this entity because FAI is currently believed to be an important contributor to the early development of osteoarthritis in young patients. However, the natural history of this disorder has not been established, and there is some controversy about the significance of radiologic manifestations of FAI because they can be seen in asymptomatic individuals. The role of the radiologist in the assessment of FAI is 2-fold, screening and definitive evaluation. Screening is usually performed through plain radiography but the findings of FAI may also be recognized on wide field-of-view (FOV) magnetic resonance (MR) imaging (MRI) of the pelvis that is frequently performed for the general evaluation of hip pain. The interpreting radiologist must be sensitive to often subtle findings that may indicate that FAI is responsible or contributing to pain in young patients. Definitive evaluation is usually performed with dedicated imaging of the symptomatic hip by MRI arthrography although noncontrast imaging and, to a lesser extent, computed tomography (CT) have roles in the assessment of suspected FAI.

ACR Appropriateness Criteria Acute Hip Pain—Suspected Fracture

Substantial cost, morbidity, and mortality are associated with acute proximal femoral fracture and may be reduced through an optimized diagnostic imaging workup. Radiography represents the primary diagnostic test of choice for the evaluation of acute hip pain. In middle aged and elderly patients with negative radiographs, the evidence indicates MRI to be the next diagnostic imaging study to exclude a proximal femoral fracture. CT, because of its relative decreased sensitivity, is only indicated in patients with MRI contraindications. Bone densitometry (DXA) should be obtained in patients with fragility fractures. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances where evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

ACR Appropriateness Criteria Follow-Up of Malignant or Aggressive Musculoskeletal Tumors.

Appropriate imaging modalities for the follow-up of malignant or aggressive musculoskeletal tumors include radiography, MRI, CT, (18)F-2-fluoro-2-deoxy-D-glucose PET/CT, (99m)Tc bone scan, and ultrasound. Clinical scenarios reviewed include evaluation for metastatic disease to the lung in low- and high-risk patients, for osseous metastatic disease in asymptomatic and symptomatic patients, for local recurrence of osseous tumors with and without significant hardware present, and for local recurrence of soft tissue tumors. The timing for follow-up of pulmonary metastasis surveillance is also reviewed. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every three years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Validity of conventional radiography in determining scaphoid waist fracture displacement.

Objective: This study examines interpreter accuracy and interobserver agreement in evaluating conventional radiographs for scaphoid waist fracture displacement. Methods: Six fresh-frozen cadaver arms were obtained transected above the elbow. A waist fracture was created in each scaphoid. In a random fashion, three of the fractures were displaced 1 mm in the radial-ulnar plane, whereas the other three were reapproximated to anatomic position before all fractures were stabilized with radiolucent adhesive glue. A three-view conventional radiography series consisting of a posterior-anterior, lateral, and ulnar-deviated elongated scaphoid view was obtained for each wrist. Each radiograph was then presented in the same sequence for interpretation to six independent observers: two hand surgeons, two musculoskeletal radiologists, and two senior orthopaedic surgery residents who were all blinded to the actual fracture pattern. Results: In 14 of the 18 (78%) displaced fracture radiographic series, the interpreters correctly recognized displacement being present. However, displacement was also reported in six of the 18 (33%) nondisplaced fracture series. The estimated overall accuracy of all readings for distinguishing between displaced and nondisplaced fractures was 72%. Of the 90 total possible pairwise agreements between interpreters regarding fracture displacement, there were 54 actual agreements (60%), and kappa was estimated to be 0.31. Taken together, these two measures of agreement can be interpreted as indicating poor to moderate agreement. Conclusion: Our results suggest that conventional radiography is not reliable in determining 1-mm scaphoid waist fracture displacement in the radioulnar plane and also indicated a lack of strong interobserver agreement.

ACR Appropriateness Criteria® Suspected Osteomyelitis, Septic Arthritis, or Soft Tissue Infection (Excluding Spine and Diabetic Foot)

Infection of the musculoskeletal system is a common clinical problem. Differentiating soft tissue from osseous infection often determines the appropriate clinical therapeutic course. Radiographs are the recommend initial imaging examination, and although often not diagnostic in acute osteomyelitis, can provide anatomic evaluation and alternative diagnoses influencing subsequent imaging selection and interpretation. MRI with contrast is the examination of choice for the evaluation of suspected osteomyelitis, and MRI, CT, and ultrasound can all be useful in the diagnosis of soft tissue infection. CT or a labeled leukocyte scan and sulfur colloid marrow scan combination are alternative options if MRI is contraindicated or extensive artifact from metal is present. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

MR imaging assessment of arthritis of the knee.

The magnetic resonance (MR) imaging presentations of arthritis of the knee are important for radiologists to recognize because these disorders are often clinically unsuspected. When they are known or clinically suspected, knowledge of imaging features allows for the confirmation and characterization of the extent of disease. This article reviews the fundamental MR imaging manifestations of rheumatologic disorders of the knee and their presentation in specific arthropathies.

Primary osseous tumors of the spine.

Primary osseous spinal tumors are relatively rare in comparison with metastatic disease, myeloma, and lymphoma. Despite their rarity, the interpreting radiologist must be aware of the typical imaging features to provide appropriate diagnosis for guidance of clinical management. The age of occurrence, distribution longitudinally in the spine, and distribution axially within the vertebra combined with typical imaging appearances can help indicate the correct diagnosis. This article reviews the diagnostic features of benign and malignant primary bone spinal tumors.

Arthritis Mimicking Sports-Related Injuries

Arthritis, including inflammatory, crystal deposition, and synovial proliferative disorders, may mimic sports injury. The purpose of this article is to review the clinical and radiologic findings of arthropathies that can present in athletes and be confused with internal derangement.