Eric A. Walker

High Prevalence of Pelvic and Hip Magnetic Resonance Imaging Findings in Asymptomatic Collegiate and Professional Hockey Players

Background: Prior retrospective studies have reported magnetic resonance imaging (MRI) findings of common adductor–abdominal rectus enthesopathy and acetabular labral tear in athletes treated for athletic pubalgia and hip pain. The true prevalence of these findings and association with symptoms in this population is unknown. Purpose: This study was undertaken to determine the prevalence of pelvic and hip MRI findings and association with clinical symptoms in professional and collegiate hockey players. Study Design: Cross-sectional study; Level of evidence, 3. Methods: The study included 21 professional and 18 collegiate hockey players. Self-reported symptoms were measured using a modified Oswestry Disability Questionnaire. Participants underwent 3-T MRI evaluation of the pelvis and hips. The MRI scans were interpreted independently by 3 musculoskeletal radiologists in 2 sessions separated by 3 months using a 5-point Likert scale to assess for features associated with common adductor–abdominal rectus dysfunction and hip pathology. To estimate prevalence, MRI findings rated 4 or higher on 4 of the 6 interpretations were considered positive. A variance component analysis was applied to determine intrareader and interreader reliability and the lower 95% confidence limits (CLs). Results: No participants reported symptoms related to pelvic or hip disorders. The MRI findings of common adductor–abdominal rectus dysfunction were observed in 14 of 39 participants (36%) and hip pathologic changes in 25 of 39 (64%). There was moderate agreement between readings, with intrareader and interreader reliabilities ranging from 0.37 to 1.00. The interreader reliability was less for evaluation of hip pathologic abnormalities than for groin pathologic abnormalities, with the lowest reliability observed in reporting of hip osteochondral lesions (0.37 with lower 95% CL of 0.22) and fluid in the primary cleft (0.45 with lower 95% CL of 0.29) and perfect reliability in the absence of effusion and abdominal rectus tendon tears. Overall, 30 of 39 (77%) asymptomatic hockey players demonstrated MRI findings of hip or groin pathologic abnormalities. Conclusion: Given the high prevalence of MRI findings in asymptomatic hockey players, it is necessary to cautiously interpret the significance of these findings in association with clinical presentation. Future investigations will determine whether these asymptomatic findings predict future disabilities.

Tenosynovial (extraarticular) chondromatosis: An analysis of 37 cases of an underrecognized clinicopathologic entity with a strong predilection for the hands and feet and a high local recurrence rate

Tenosynovial chondromatosis is a multinodular cartilaginous proliferation that arises from the tenosynovial membranes. This report describes the clinical, radiologic, and histopathologic findings in 37 cases of this uncommon entity. There were 17 males and 20 females, ranging in age from 20 to 86 years (mean and median age, 46 years). The process involved tenosynovium of the fingers (n = 19), feet (n = 8), wrists (n = 4), ankles (n = 2), hand, not otherwise specified, or palm (n = 2), knee (n = 1), and forearm (n = 1). Signs of disease or symptoms were present for 5 weeks to 18 years (median duration, approximately 2 years) before surgical excision. The two most common complaints were a painless mass and a mass that was mildly tender with pressure. None of the tumors had clinical, radiologic, or histopathologic evidence of articular or bone involvement. Histologically, all tumors consisted of a multinodular cartilaginous proliferation involving tenosynovium and/or subsynovial connective tissue. Mild or moderate atypia, as encountered in chondroma of soft parts and synovial chondromatosis, was a frequent finding. Follow-up information was available for 16 patients (43%). Only two patients with follow-up information remained disease free after their initial surgical procedure. Seven patients had one recurrence and seven patients had two or more recurrences. Tenosynovial chondromatosis appears to be an extraarticular counterpart of synovial (intraarticular) chondromatosis. Our review indicates this process is often confused with chondroma of soft parts, in part, because both entities have a predilection for the hands and feet. Diagnosis of this underrecognized entity is of clinical importance because of the high local recurrence rate.

Magnetic Resonance Imaging of Benign Soft Tissue Neoplasms in Adults

This article reviews a spectrum of benign soft tissue tumors found in adults. Rather than presenting a complete review, the focus of this article is on benign tumors for which the diagnosis may be confidently made or strongly suggested on the basis of imaging. Diagnoses presented include nodular fasciitis, superficial and deep fibromatosis, elastofibroma, lipomatous lesions, giant cell tumor of the tendon sheath, pigmented villonodular synovitis, peripheral nerve sheath tumors, Morton neuroma, hemangioma, and myxoma.

Imaging Features of Superficial and Deep Fibromatoses in the Adult Population

The fibromatoses are a group of benign fibroblastic proliferations that vary from benign to intermediate in biological behavior. This article will discuss imaging characteristics and patient demographics of the adult type superficial (fascial) and deep (musculoaponeurotic) fibromatoses. The imaging appearance of these lesions can be characteristic (particularly when using magnetic resonance imaging). Palmar fibromatosis demonstrates multiple nodular or band-like soft tissue masses arising from the proximal palmar aponeurosis and extending along the subcutaneous tissues of the finger in parallel to the flexor tendons. T1 and T2-weighted signal intensity can vary from low (higher collagen) to intermediate (higher cellularity), similar to the other fibromatoses. Plantar fibromatosis manifests as superficial lesions along the deep plantar aponeurosis, which typically blend with the adjacent plantar musculature. Linear tails of extension (“fascial tail sign”) along the aponeurosis are frequent. Extraabdominal and abdominal wall fibromatosis often appear as a heterogeneous lesion with low signal intensity bands on all pulse sequences and linear fascial extensions (“fascial tail” sign) with MR imaging. Mesenteric fibromatosis usually demonstrates a soft tissue density on CT with radiating strands projecting into the adjacent mesenteric fat. When imaging is combined with patient demographics, a diagnosis can frequently be obtained.

Magnetic Resonance Imaging of Malignant Soft Tissue Neoplasms in the Adult

This review addresses the spectrum of malignant soft tissue tumors frequently found in adults. Rather than presenting a complete review, the focus of this discussion is on common lesions or lesions in which the diagnosis may be suggested on the basis of imaging. Diagnoses covered include undifferentiated high-grade pleomorphic sarcoma, fibrosarcoma, dermatofibrosarcoma protuberans, liposarcoma, synovial sarcoma, malignant peripheral nerve sheath tumor, clear cell sarcoma, hemangioendothelioma, hemangiopericytoma, angiosarcoma, and leiomyosarcoma.

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.

Soft-Tissue Myxomatous Lesions: Review of Salient Imaging Features with Pathologic Comparison

Myxoid soft-tissue lesions are a heterogeneous group of benign and malignant mesenchymal tumors with an abundance of extracellular mucoid material. These lesions may mimic cysts on radiologic evaluation because of the high water content, and histopathologic features also overlap. Benign myxoid lesions include intramuscular myxoma, synovial cyst, bursa, ganglion, and benign peripheral nerve sheath tumor, including neurofibroma and schwannoma. Malignant entities include myxoid liposarcoma, myxoid leiomyosarcoma, myxoid chondrosarcoma, ossifying fibromyxoid tumor, and myxofibrosarcoma. Some syndromes are associated with myxoid soft-tissue lesions, such as Mazabraud syndrome in patients with soft-tissue myxomas and fibrous dysplasia. Certain discriminating features, such as intralesional fat in a myxoid liposarcoma, perilesional edema and a rim of fat in soft-tissue myxoma, and the swirled T2-weighted signal intensity and enhancement pattern of aggressive angiomyxoma, assist the radiologist in differentiating these lesions. The presence of an internal chondroid matrix or incomplete peripheral ossification may suggest myxoid chondrosarcoma or ossifying fibromyxoid tumor, respectively. The entering-and-exiting-nerve sign is suggestive of a peripheral nerve sheath tumor. Communication with a joint or tendon sheath and peripheral enhancement may indicate a ganglion or synovial cyst. This article (a) reviews the magnetic resonance, computed tomographic, and ultrasonographic imaging characteristics of soft-tissue myxomatous lesions, emphasizing imaging findings that can help differentiate benign and malignant lesions; (b) presents differential diagnoses; and (c) provides pathologic correlation.

Magnetic Resonance Imaging of Soft-Tissue Masses

Benign soft-tissue lesions outnumber their malignant counterparts by a factor of 100:1,1 but many are small and superficial and do not lead to imaging or biopsy. Softtissue sarcomas are estimated to represent 1% of malignant tumors.2,3 The incidence of soft-tissue sarcoma revealed a rate of 2.7 per 100,000.4 The incidence of soft-tissue sarcoma increases significantly with age, and in patients 80 and older is 8 per 100,000.5 Magnetic resonance (MR) imaging (MRI) is the favored modality for evaluation of soft-tissue tumors and tumor-like conditions. It is valuable for lesion detection, diagnosis, and staging. Although advances in thin-section computed tomography (CT) have recently allowed detailed multiplanar reconstructions, MRI allows superior soft-tissue contrast without radiation exposure. When planning an MRI study for evaluation of a soft-tissue lesion at least 2 orthogonal planes should be obtained. In our experience lesions are typically best evaluated in the axial plane and this is usually the most familiar to radiologists. The secondary plane of imaging for an anterior or posterior lesion is typically the sagittal plane. Coronal sequences are optimal for evaluation of medial or lateral masses. T1-weighted (T1W) and T2-weighted (T2W) sequences should be obtain as most soft-tissue lesions have been described with their spin-echo (SE) T1W and T2W signal characteristics. Fast SE sequences in place of SE sequences can reduce scanning time and patient motion artifacts. Gradientecho sequences can be useful in demonstrating hemosiderin with “blooming,” but also is subject to artifact caused by metal, hemorrhage, and air. Short tau inversion recovery and T2 fat saturation images increase sensitivity to abnormal tissue containing increased water content. However, these techniques also reduce information concerning various tissue consistencies and should be used in the secondary, not the primary plane of imaging. The smallest diagnostic field of view is preferable when evaluating these lesions. The use of intravenous contrast in lesion evaluation is controversial, but can be useful. Gadolinium contrast agents increase the T1W signal intensity of many soft-tissue tumors, allowing distinction between tumor and muscle or tumor and edema, but the surrounding area of edema may enhance as well. Information about tumor vascularity is also obtained.6,7 Contrast may allow distinction of small tumor nodules in a predominantly cystic lesion or a “spontaneous hematoma.” Malignant lesions may show increased neovascularity at their periphery and high interstitial pressure at their center leading to a high rim-to-center differential enhancement ratio.8 The use of intravenous contrast also increases the cost and length of time of the examination. Severe reactions to gadolinium and nephrogenic systemic fibrosis are rare, but they do occur. Many investigators have evaluated if dynamic enhancement with gadolinium can help differentiate benign from malignant soft-tissue lesions.6,9,10 High soft-tissue vascularity and perfusion demonstrates an increased rate of enhancement. Malignant lesions usually reveal greater enhancement and an increased rate of enhancement.11 One difficulty with dynamic contrast-enhanced imaging is a significant overlap between the rate of enhancement of benign and malignant lesions.12 We do not routinely perform dynamic enhancement sequences, at our institutions. Although MR imaging is excellent at delineating soft-tissue lesions, a correct histologic diagnosis based on imaging studies alone is seen in only 25%-30% of cases.13-15 However, we believe that this percentage continues to increase and ultimately will approach the 75%-90% range.16 Most cases are nonspecific with intermediate T1 and intermediate to high T2 signal. A specific diagnosis should be obtained by using a combination of lesion signal intensity, location, growth pattern, and other unique characteristics of the lesion. Unless a specific diagnosis can be determined, the lesion should be considered indeterminate and an appropriate biopsy path should be discussed with the orthopedic oncologist or treating surgeon. A poorly selected biopsy path may violate compartments needed for reconstruction and an amputation may result. Some authors have proposed that criteria such as tumor margins, homogenous vs. heterogeneous signal intensity, *Departments of Radiology and Nuclear Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD. †Department of Radiology, Milton S. Hershey Medical Center, Hershey, PA. ‡Department of Radiologic Pathology, Armed Forces Institute of Pathology, Washington, DC. The opinions or assertions contained herein are the private views of the authors and are not to be construed as official nor as reflecting the views of the Departments of the Army, Navy, or Defense. Address reprint requests to Eric A. Walker, MD, Department of Radiology, Milton S. Hershey Medical Center, 266 Townhouse, Hershey, PA 17033. E-mail: ewalker@psu.edu

Chondrosarcoma: A Diagnostic Imager's Guide to Decision Making and Patient Management.

Chondrosarcoma is the third most common primary malignant bone tumor. Currently, outcomes are based largely on a histologic grading scale described by the World Health Organization (WHO) Classification of Bone Tumors (2002). This classification scheme possesses evident utility in the evaluation and management of higher grade tumors, but it is often unable to distinguish enchondromas from low-grade chondrosarcomas. This is problematic when low-grade lesions that are histologically similar to enchondromas demonstrate aggressive imaging features. Because histologic classification alone often belies the clinical significance of chondroid lesions, it is also important to consider radiologic staging as part of the clinical decision making process. This article focuses on medical decision support considerations relevant when confronted with this challenging subset of chondroid tumors, particularly differentiating the benign enchondroma from its notorious relative, the low-grade chondrosarcoma. In doing so, we present a review of the salient imaging features and discuss key differentiating characteristics.

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.