Diffusion-weighted magnetic resonance imaging of spinal bone marrow

Diffusion-weighted (DW) imaging is an alternative source of image contrast. DW imaging enables to measure the random motion of free water protons on a molecular basis by using different imaging sequences including steady-state free precession imaging, navigated spin-echo DW imaging, and single-shot echo planar imaging. Analysis of intravoxel incoherent motion of water protons is a promising tool that has shown to be of value in the differential diagnosis between benign and malignant spontaneous vertebral fractures. Acute benign osteoporotic fractures show hypo- or isointense signal on DW sequences that reflects persistent free water proton mobility. With increasing diffusion strength a substantial signal loss is found. Metastatic fractures show hyperintensity compared with normal surrounding bone marrow probably due to altered water proton mobility within neoplasm. The ability of the different methods for DW imaging to differentiate other bone marrow alterations needs to be investigated in further studies.