Diffusion-weighted imaging of the musculoskeletal system in humans

This article reviews the principles of diffusion-weighted imaging (DWI) and recent results in DWI of the musculoskeletal system. The potential of DWI in the diagnosis of pathology of the musculoskeletal system is discussed. D WI is a relatively new MR imaging technique that has already been establish ed in neuroradiology, especially in the early detection of brain ischemia. The random motion of water protons on a molecular basis can be measured wit h DWI. To date DWI of the abdomen and of the musculoskeletal system has onl y been employed in scientific studies, but first results indicate that it m ay also be beneficial in these fields. Different diffusion characteristics have been found in normal tissues such as muscle, fat and bone marrow. Also , pathologic entities such as neoplasms, post-therapeutic soft tissue chang es and inflammatory processes can be differentiated. Normal muscle shows si gnificantly higher diffusion values than subcutaneous fat and bone marrow, due to a higher mobility of water protons within muscle. Soft tissue tumors exhibit a significantly lower diffusion value compared with post-therapeut ic soft tissue changes and inflammatory processes. Necrotic tumor tissue ca n be distinguished from viable tumor due to significantly higher diffusion of water protons within necrotic tissue.