The radiological diagnosis of infection

Musculoskeletal infections can involve bone, joints, muscles and soft tissues. The interpretation of imaging in musculoskeletal infections can be a diagnostic challenge and requires an integrated approach with clinical details and blood inflammatory markers. Imaging also plays a vital role in treatment planning and follow up. Conventional plain film radiography is still the cornerstone, which provides an overview of the bone and surrounding soft tissue pathology and should routinely be the first imaging procedure in patients with suspected musculoskeletal infection. The sensitivity of radiographs for the detecting of acute osteomyelitis is limited. Ultrasound can be used to assess soft tissue collections, joint effusions, and foreign body localization. It is invaluable in providing guidance for diagnostic joint aspiration, biopsy or therapeutic drainage of a soft tissue abscess/collection. CT scans are useful in providing bony detail and are particularly useful for evaluation of presence of sequestrum and in cases where MRI is contraindicated. MRI provides excellent anatomical details and evaluates both the soft tissues and bones and is the most sensitive and specific imaging modality for evaluating musculoskeletal infection. Radionuclide imaging can be helpful in cases of acute osteomyelitis and multifocal infection and has a high negative predictive value when normal.