CT and MRI evaluation of musculoskeletal infection.

While the plain film and nuclear medicine bone scan are still the traditional imaging modalities used in the evaluation of musculoskeletal infection, the cross-sectional imaging modalities, computed tomography (CT) and magnetic resonance imaging (MRI), have become critical in the delineation of many types of musculoskeletal infection. In particular, the evaluation of soft tissue infections, including cellulitus, myositis, fasciitis, abscess, and septic arthritis are often best evaluated by MRI or CT due to their excellent anatomic resolution and soft tissue contrast. Even in osseous infection, CT and MRI can give better anatomic delineation of the extent of infection. In cases where the plain film and nuclear medicine bone scan findings are complicated due to previous surgery, trauma, or underlying illness, the anatomic resolution and soft tissue contrast provided by MRI and CT are often necessary to determine if underlying infection exists. MRI's visualization of the bone marrow allows for the sensitive detection of osteomyelitis, although specificity for the diagnosis of osteomyelitis is aided by other findings, including cortical destruction. The CT and MRI findings in the spectrum of musculoskeletal infections are discussed and contrasted, and pitfalls in their evaluation of musculoskeletal infection are described.