Radiographics : a review publication of the Radiological Society of North America, Inc
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Diffusion-weighted (DW) imaging is a functional magnetic resonance (MR) imaging technique that can readily be incorporated into a routine non-contrast material-enhanced MR imaging protocol with little additional scanning time. DW imaging is based on changes in the Brownian motion of water molecules caused by tissue microstructure. The apparent diffusion coefficient (ADC) is a quantitative measure of Brownian movement: Low ADC values typically reflect highly cellular microenvironments in which diffusion is restricted by the presence of cell membranes, whereas acellular regions allow free diffusion and result in elevated ADC values. ⋯ Studies of the use of DW imaging in assessing the treatment response of both osseous and soft-tissue tumors have shown that higher ADC values correlate with better response to cytotoxic therapy. Successful application of DW imaging in the evaluation of musculoskeletal lesions requires familiarity with potential diagnostic pitfalls that stem from technical artifacts and confounding factors unrelated to lesion cellularity. Further investigation is needed to evaluate the impact of DW imaging-ADC mapping on management and outcome in patients with musculoskeletal lesions.
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US for diagnosis of musculoskeletal conditions in the young athlete: emphasis on dynamic assessment.
Ultrasonography (US) is increasingly recognized as an important tool for diagnosis and therapeutic management of a variety of musculoskeletal conditions. Advantages of US use in the young athlete include the ability to diagnose dynamic conditions that are occult with other modalities, provide additional diagnostic information, and aid in treatment. Uses of US in young patients include evaluation of acquired musculoskeletal conditions that manifest with symptoms and assessment of congenital variants that may manifest with pain or limitations in activity. ⋯ Pathologic processes associated with congenital variants in the upper extremities include slipping rib syndrome, atraumatic anterior subluxation of the sternoclavicular joint, and snapping triceps syndrome. Conditions that affect the lower extremities include internal and external snapping hip syndrome, snapping knee syndrome, and medial plica syndrome. The dynamic capability of US is ideal for diagnosis of many conditions that affect the musculoskeletal system of the young athlete, many of which would be difficult or impossible to identify with use of other imaging modalities.