Musculoskeletal infection of the extremities: evaluation with MR imaging

Magnetic resonance (MR) imaging was performed in 17 patients, 11-84 years of age, referred for evaluation of possible osteomyelitis involving the appendicular skeleton. MR imaging permitted successful identification of osteomyelitis in ten patients (four acute, two subacute with Brodie abscess, two chronic, and two acute with septic arthritis) and of cellulitis in the absence of osteomyelitis in four patients, including one with a soft-tissue abscess. Active osteomyelitis was excluded in three patients. Both T1- and T2-weighted spin-echo sequences were needed to evaluate osteomyelitis. T2-weighted images were needed to identify foci of active infection. MR images provided more accurate and detailed information regarding the extent of involvement than did radionuclide bone scans, computed tomographic scans, or standard radiographs. It permitted the differentiation of septic arthritis or cellulitis from osteomyelitis. In this limited series, MR imaging was particularly useful for seeking foci of active infection in areas of chronic osteomyelitis complicated by surgical intervention or fracture.