Whole-Body MRI of Inflammatory and Infectious Musculoskeletal Diseases: Emphasis on Chronic Nonbacterial Osteomyelitis and Systemic Inflammatory Disorders

Whole-body magnetic resonance imaging (WBMRI) has emerged as the primary imaging tool for multifocal inflammatory and infectious musculoskeletal diseases. By extending coverage from the vertex to the toes in a single, radiation-free examination, WBMRI enables the detection of clinically occult lesions, disease-specific pattern recognition across bone marrow, joints, entheses, and muscles, and objective monitoring of disease activity and treatment response. This review describes the WBMRI findings—with detailed imaging features and distribution patterns—in chronic nonbacterial osteitis, SAPHO syndrome, seronegative spondyloarthritis, rheumatoid arthritis, juvenile idiopathic arthritis, polymyalgia rheumatica, idiopathic inflammatory myopathies, and fever of unknown origin, with emphasis on validated quantitative scoring tools, disease-specific acquisition protocols, and structured reporting strategies for the practicing radiologist. WBMRI provides unique clinical value by mapping total lesion burden, supporting differential diagnosis, identifying biopsy targets, and tracking treatment response. Disease-specific protocols—tailored to the pathophysiological target of each condition—are essential for maximizing diagnostic yield. Quantitative scoring tools and advanced MRI sequences may improve the characterization of disease burden and longitudinal assessment.