Magnetic resonance: new approaches to imaging of the musculoskeletal system.

Recent technical advances in magnetic resonance imaging are reviewed. Purpose designed musculoskeletal magnetic resonance (MR) systems are now available. A great deal of pulse sequence development has been carried out with ultrashort TE (UTE) imaging, blood oxygenation level detection (BOLD) studies, diffusion weighted and other sequences. Image processing and measurement techniques have improved. In hyaline articular cartilage the deep layer can now be identified. Contrast agents are now being used to study the reduction in proteoglycans in cartilage. Enhancement is seen in tendons, ligaments and menisci and can be used to study perfusion. Signal is detected from cortical bone and periosteum and this can be used to monitor perfusion in serial studies. Muscle metabolism can also be studied. Contrast transport into intervertebral discs can be observed as well as effects attributable to iron deposition.