[Osteomyelitis in adults]

Osteomyelitis (OM) refers to inflammatory diseases of the bone caused by microorganisms. A continuous increase in the prevalence of osteomyelitis has been observed. Despite advances in medical care, early diagnosis remains challenging due to initially nonspecific symptoms, particularly in elderly or immunocompromised patients.

This article aims to provide a structured overview of the pathogenesis of OM, the role of imaging, and the most important differential diagnoses.

Narrative, literature-based review incorporating current guidelines, radiological protocols, and imaging characteristics.

Magnetic resonance imaging (MRI) is the diagnostic gold standard. It enables early detection of bone marrow edema and inflammatory changes. The "penumbra sign" and the "ghost sign" contribute in distinguishing tumors and Charcot arthropathy, respectively. Computed tomography (CT) is essential for chronic OM and sequestrum detection. Flourodeoxyglucose-18 positron emission tomography (FDG-PET) can be helpful in unclear cases, particularly in patients with prosthetic implants.

A multidisciplinary, imaging-guided approach is critical for early diagnosis, treatment planning, and follow-up in OM. Radiological signs such as the penumbra and ghost signs assist in differentiating from other conditions. Advances in MRI techniques (e.g., zero time echo [ZTE] sequences) and the use of hybrid nuclear medicine procedures expand diagnostic capabilities, enhance surgical planning, and optimize therapy and follow-up.