Whole Body MRI in the Diagnosis of Paediatric CNO/CRMO

Chronic recurrent multifocal osteomyelitis (CRMO) is an auto-inflammatory disorder affecting the skeleton of children and adolescents. Whole body MRI (WBMRI) is key in diagnosis and follow-up of CRMO. Imaging protocols should include sagittal STIR of the spine, imaging of the hands and feet and T1 images for distinguishing normal bone marrow. CRMO lesions can be metaphyseal, epiphyseal and physeal – potentially causing growth disturbance and deformity. Spinal lesions are common, important and can cause vertebral collapse. Lesion patterns include multifocal tibial and pauci-focal patterns which follow a predictable presentation and course of disease. Common pitfalls of WBMRI include hematopoietic marrow signal, metaphyseal signal early on in bisphosphonate therapy and normal high T2 signal in the hands and feet. Pictorial reporting assists in recording lesions and follow-up over time. The purpose of this paper is to review the different WBMRI protocols, imaging findings, lesion patterns and common pitfalls in children with CRMO.