This lecture introduces chronic nonbacterial osteomyelitis (CNO/CRMO) in children and highlights the role of whole-body MRI in its diagnosis. It emphasizes that CNO is an autoinflammatory, multifocal, relapsing bone disorder rather than true infectious osteomyelitis, and focuses on characteristic imaging patterns that help distinguish it from infection and malignancy. The session also addresses common diagnostic pitfalls, clinical–imaging discordance, and when biopsy can be avoided based on typical MRI findings.

Learning Objectives

By the end of this session, participants will be able to:

• Define CNO/CRMO and distinguish it from infectious osteomyelitis
• Recognize typical clinical features, including insidious pain and multifocal disease in children and adolescents
• Identify key whole-body MRI patterns, including metaphyseal and apophyseal bone marrow edema
• Recognize characteristic distribution patterns (long bones, pelvis, spine, clavicle, ankles)
• Understand the role of whole-body MRI and diffusion-weighted imaging in assessing disease extent
• Differentiate CNO from major mimics such as infection, tumors, and hematologic disease
• Appreciate typical diagnostic delay and frequent clinical–imaging mismatch
• Understand when imaging findings are sufficiently characteristic to avoid biopsy