Hip anatomic variants that may mimic abnormalities at MRI: labral variants.

OBJECTIVE: Normal anatomic variants of the acetabular labrum are observed on MR images and include labral variants, several sublabral sulci, and perilabral sulcus. Because variants can be misidentified as labral abnormalities such as labral tears, the radiologist needs to avoid the pitfall of mistaking variants as abnormalities. CONCLUSION: The hip has multiple anatomic variants that can mimic abnormalities at hip MRI. The labrum has several anatomic variants that can be confused with true labral tears.

Hip anatomic variants that may mimic pathologic entities on MRI: nonlabral variants.

OBJECTIVE: The hip has several anatomic variants that may be mistaken for pathologic abnormalities. The radiologist needs to be able to distinguish these variants from true abnormalities. In this review, we present nonlabral variants of the hip that can be seen on MRI. CONCLUSION: The hip has multiple anatomic variants that may mimic disease on hip MRI. Like labral variants, nonlabral variants can be confused for true abnormalities.

Diabetic myopathy: MRI patterns and current trends.

OBJECTIVE: This study retrospectively evaluates diabetic myopathy in a large referral hospital population. It describes the MRI findings and the distribution of muscle involvement, including comparison with clinical parameters. MATERIALS AND METHODS: MRI reports of the lower extremities from July 1999 through January 2006 were reviewed and compared with clinical parameters for patients with diabetic myopathy. Clinical parameters (e.g., type of diabetes, hemoglobin A(1C) level, creatine kinase level, and erythrocyte sedimentation rate [ESR]) and the presence of complications, including nephropathy, neuropathy, and retinopathy, were noted. The distribution of muscle involvement and imaging features were reviewed. RESULTS: Over a 79-month period, 21 extremities (11 thighs and 10 calves) of 16 patients were imaged. Fourteen (88%) patients had type 2 diabetes, and two (12%) had type 1 diabetes. Four patients (25%) had disease in more than one location. In the thigh, the anterior compartment was involved in all patients. The posterior compartment was affected in nine (90%) of 10 calves. Muscle infarction and necrosis was seen in eight (38%) extremities. The creatine kinase level, ESR, and hemoglobin A(1C) level were elevated in the majority of cases. Coexisting nephropathy (50%), neuropathy (50%), and retinopathy (38%) were present in these patients. CONCLUSION: Diabetic myopathy may occur more frequently in patients with type 2 diabetes than previously reported. In this population, T2-weighted and contrast-enhanced images have similar findings, and the increased coexistence of nephropathy makes administration of gadolinium-based contrast agents ill-advised. With a typical clinical presentation and MRI findings, a confident diagnosis can be made, and potentially harmful biopsy is avoided. Diabetic myopathy encompasses a spectrum of diseases, including muscle inflammation, ischemia, hemorrhage, infarction, necrosis, fibrosis, and fatty atrophy. It is usually seen with long-standing, poorly controlled diabetes.

Schatzker classification of tibial plateau fractures: use of CT and MR imaging improves assessment.

The Schatzker classification system for tibial plateau fractures is widely used by orthopedic surgeons to assess the initial injury, plan management, and predict prognosis. Many investigators have found that surgical plans based on plain radiographic findings were modified after preoperative computed tomography (CT) or magnetic resonance (MR) imaging. The Schatzker classification divides tibial plateau fractures into six types: lateral plateau fracture without depression (type I), lateral plateau fracture with depression (type II), compression fracture of the lateral (type IIIA) or central (type IIIB) plateau, medial plateau fracture (type IV), bicondylar plateau fracture (type V), and plateau fracture with diaphyseal discontinuity (type VI). Management of type I, II, and III fractures centers on evaluating and repairing the articular cartilage. The fracture-dislocation mechanism of type IV fractures increases the likelihood of injury to the peroneal nerve or popliteal vessels. In type V and VI fractures, the location of soft-tissue injury dictates the surgical approach and the degree of soft-tissue swelling dictates the timing of definitive surgery and the need for provisional stabilization with an external fixator. CT and MR imaging are more accurate than plain radiography for Schatzker classification of tibial plateau fractures, and use of cross-sectional imaging can improve surgical planning.

Pulmonary fat embolism after pelvic and long bone fractures in a trauma patient.

Fat embolism is a common complication of pelvic and long bone fractures. Macroscopic fat emboli in the pulmonary arteries on computed tomography have been reported postoperatively after fixation of long bone fractures for trauma, however the quantification of attenuation values of fat emboli have been infrequently reported in the literature. We present a case of pulmonary fat embolism in a 52-year-old female after acute bony trauma sustained during a motor vehicle accident. To the authors' knowledge however, pulmonary fat embolism has not been described on the initial trauma CT scan.

Multimodality imaging in the diagnosis of deep vein thrombosis and popliteal pseudoaneurysm complicating a sessile osteochondroma.

Synergistic use of ultrasonography, radiography, multidetector CT (MDCT) and MRI enabled a prompt and accurate diagnosis of a nonocclusive popliteal vein thrombus (deep venous thrombosis, DVT) and a pseudoaneurysm complicating a sessile osteochondroma in an 11-year-old boy who presented in the emergency department with sudden-onset nontraumatic pain in the posterior aspect of the knee.

Calcaneal fractures: what the surgeon needs to know.

The calcaneus is an uncommonly fractured bone that plays a critical role in foot biomechanics, weight-bearing, and the ability to wear a shoe. The radiologist acts as a consultant during screening, operative planning, and follow-up imaging of these often complex injuries. Effective communication between radiologist and surgeon requires an understanding of calcaneal anatomy, goals of surgical reduction, and factors that affect patient management and outcomes. In the following pictorial review we will discuss radiologic screening/classification/characterization and their correlation with surgical management and patient morbidity.

Avulsions around the knee portend instability.

Bony avulsions about the knee are common injuries seen in the emergency room. Unawareness of characteristic radiographic patterns of injury that herald potential instability and require further workup can result in significant morbidity. We present a radiographic pictoral discussion on bony avulsions and associated soft tissue complex injuries on MRI. Emphasis is on injuries leading to instability, and often surgical management. MRI is a useful imaging tool for screening and surgical planning in this setting of patients.

Gout: a clinical and radiologic review.

Gout is a group of diseases characterized by arthritis and results from a disturbance of urate metabolism with the deposition of monosodium urate crystals in the joints and soft tissues. Often, but not invariably, the serum urate levels are elevated as a result of overproduction or underexcretion of uric acid. Clinical manifestations include acute and chronic arthritis, tophaceous deposits, interstitial renal disease, and uric acid nephrolithiasis. The diagnosis is based on the identification of uric acid crystals in joints, tissues, or body fluids. Acute episodes are treated with colchicine, NSAIDs, or steroids. Long-term management includes treatment with uricosuric agents or xanthine oxidase inhibitors.

Prevalence and patterns of occult hip fractures and mimics revealed by MRI.

OBJECTIVE: The diagnosis of hip fractures can be difficult on radiography alone. MRI is frequently used to confirm or deny the presence of a minimally displaced hip fracture. This study evaluates the patterns of injury seen on MRI that are difficult to diagnose on radiography. MATERIALS AND METHODS: MRIs of 73 patients who were examined for possible hip fractures and whose radiographic findings were negative or equivocal for hip fracture were reviewed. Seventy-six studies were performed in 73 patients who were between 24 and 102 years old. MRIs were evaluated for the presence and location of bone or soft-tissue injury. Muscle injuries were categorized on the basis of location and type of injury. RESULTS: Forty-six percent (35/76) of the studies showed subtle fractures. Seventeen fractures were in the proximal femur and 18 in the innominate bone. Soft-tissue abnormalities were common, found in 65% of the studies. Twenty percent of the MRI findings were considered normal because there was no apparent finding on the images to explain the patients' symptoms. CONCLUSION: Soft-tissue abnormalities are commonly seen alone or in association with subtle fractures on MRI in the evaluation of patients with a clinical suspicion of hip fracture. MRI is recommended for all symptomatic patients whose radiographic findings are negative for hip fracture.

Collar osteophytes: a cause of false-positive findings in bone scans for hip fractures.

OBJECTIVE: A retrospective review of our radiology database revealed five elderly patients, seen over a 12-month period, whose findings were judged positive for hip fractures on the basis of their bone scans, but whose MR imaging findings were negative. CONCLUSION: The presence of collar osteophytes around the femoral neck caused a false diagnosis of hip fracture for these patients, as revealed on radionuclide bone scans. CT or MR imaging correlation is needed where collar osteophytes may have caused an incorrect diagnosis of hip fracture based on a bone scan.