Which imaging modality is first-line for evaluating suspected osteomyelitis in adults?

Which imaging modality is first-line for evaluating suspected osteomyelitis in adults?

• A. MRI
• B. X-ray
• C. Ultrasound
• D. CT

Answer: (D)

Magnetic resonance imaging is the imaging modality of choice when osteomyelitis is suspected in adults because it detects bone marrow edema and early marrow and soft tissue involvement long before changes appear on X‑rays. On MRI, osteomyelitis shows marrow signal changes—low T1 and high T2/STIR—with contrast enhancement that outlines infected bone and any adjacent abscesses or soft tissue spread. This makes MRI highly sensitive and specific for the infection and also helps define the full extent for treatment planning. Plain radiographs are often normal early in the disease and only show late changes such as cortical destruction or sequestra, so they’re not reliable for initial evaluation. CT offers excellent detail of cortical bone and is useful for surgical planning or identifying bony sequestra, but it’s less sensitive to early marrow edema and soft tissue involvement. Ultrasound can detect soft tissue collections and guide drainage but doesn’t visualize marrow infection well. If MRI cannot be performed, CT or other modalities can be used, with CT providing strong anatomic detail for complicated cases.

Magnetic resonance imaging is the imaging modality of choice when osteomyelitis is suspected in adults because it detects bone marrow edema and early marrow and soft tissue involvement long before changes appear on X‑rays. On MRI, osteomyelitis shows marrow signal changes—low T1 and high T2/STIR—with contrast enhancement that outlines infected bone and any adjacent abscesses or soft tissue spread. This makes MRI highly sensitive and specific for the infection and also helps define the full extent for treatment planning.

Plain radiographs are often normal early in the disease and only show late changes such as cortical destruction or sequestra, so they’re not reliable for initial evaluation. CT offers excellent detail of cortical bone and is useful for surgical planning or identifying bony sequestra, but it’s less sensitive to early marrow edema and soft tissue involvement. Ultrasound can detect soft tissue collections and guide drainage but doesn’t visualize marrow infection well. If MRI cannot be performed, CT or other modalities can be used, with CT providing strong anatomic detail for complicated cases.