Update: Imaging of Lower Extremity Infection.

Pedal infection is a difficult diagnostic problem for clinicians and radiologists alike, especially in patients with diabetes. Vascular and neuropathic disease complicates the clinical picture and imaging appearance. Radiographs are usually the first examination ordered, offering an excellent overview of previous surgery, structural deformities, and neuropathic joint disease. Ultrasound and computed tomography are occasionally useful to answer specific questions. Scintigraphy has become less popular because MRI provides high sensitivity and specificity as well as detailed anatomical information. Almost all diabetic foot infections originate from a foot ulcer. Thus demonstrating communication from the skin to underlying bones, joints, tendons, and other structures is key. Careful examination of the soft tissues at MR imaging allows the radiologist to determine the extent of soft tissue infection, the presence of abscesses and septic tenosynovitis, as well as the presence of necrotic tissue. Pitfalls include fracture, neuropathic osteoarthropathy, neoplasia, and noninfectious inflammatory conditions such as gout.