Whole-Body MRI of Primary Bone Tumors

Magnetic resonance imaging (MRI) is the established gold standard for the staging of primary bone tumors; however, conventional protocols typically use a site-specific model supplemented by ionizing radiation for systemic screening. Recent advancements in whole-body MRI (WB-MRI) have enabled a "marrow-first" diagnostic approach, allowing for the comprehensive assessment of the primary intraosseous lesion and the entire skeleton in a single, radiation-free study. Technical developments, including Dixon fat suppression and diffusion-weighted imaging (DWI), have significantly enhanced the detection of occult skip metastases, which occur in ∼7.5% of high-grade osteosarcomas and 4.5% of Ewing sarcomas. Beyond malignant staging, WB-MRI offers distinct advantages for the longitudinal surveillance of syndromic conditions such as Ollier disease and hereditary multiple exostoses, where it facilitates a shift toward patient-initiated, symptom-led monitoring. Despite these advances, challenges remain, specifically the "chest gap" in pulmonary nodule detection and the potential for false positives from hematopoietic marrow mimics. This review discusses the technical principles, clinical applications, and diagnostic pitfalls of WB-MRI in bone tumors, emphasizing its role in optimizing staging accuracy while minimizing cumulative radiation exposure.