Role of MRI Diffusion in Differentiation Between Benign and Malignant Bony Lesions

Bone tumors are categorized according to their tissue of origin into cartilagenous, osteogenic, fibrogenic, fibrohistiocytic, haematopoietic, vascular, and lipogenic tumors. Magnetic resonance imaging (MRI) is now indispensable for the preoperative workup and therapeutic follow-up of patients with musculoskeletal tumors. The application of DW-MRI in bone marrow is today an established examination technique that provides a unique contrast and that can help in the detection of bone-marrow pathologies and the differentiation of benign and malignant bone-marrow lesions. Diffusion MRI provides quantitative and qualitative assessments of tissue cellularity and cell-membrane integrity. It is widely used for tumour detection, characterisation, and monitoring during treatment. Diffusion MRI supplies functional information that complements the structural evaluation. In combination with standard structural MRI parameters, the ADC value improves tumour characterization. Diffusion MRI can also be used to monitor tumours during chemotherapy. Tumour necrosis results in loss of cell membrane integrity and in expansion of the extracellular compartment, leading to greater water-molecule diffusion with an increase in the ADC value.