Osteomyelitis and beyond.

Musculoskeletal infections are a cause of considerable morbidity in children. Symptoms and signs are often nonspecific, and imaging is needed to define the anatomical location of infected tissue or fluid collections for diagnostic aspiration or biopsy. Prompt diagnosis and precise localization of the infection site has become even more imperative with the emergence and dissemination of highly invasive organisms such as community-acquired Staphylococcus aureus. Although radiography, bone scintigraphy and US continue to play a role, MRI is now the preferred imaging modality for definitive evaluation of pediatric musculoskeletal infections because of its capability of simultaneously assessing the osseous, articular and muscular structures without ionizing radiation exposure. This article focuses on the imaging characteristics of osteomyelitis, septic arthritis and pyomyositis and the differentiating features of potential mimics of infection.