Imaging in osteoarthritis and crystal deposition diseases.

The challenge in imaging joints and articular cartilage is to detect both early and subtle changes that may influence the treatment of osteoarthritis and crystal deposition diseases. Although radiographs show gross changes, they cannot show cartilage surfaces directly. Both ultrasonography and magnetic resonance imaging are able to demonstrate both the surface and internal details of articular cartilage. Advances in magnetic resonance imaging have begun to show internal details of articular cartilage that correspond with histologic zones. These changes can be shown using minor modifications of conventional imaging techniques. More elaborate studies using experimental contrast agents and sodium nuclear magnetic resonance imaging have shown changes in the magnetic resonance signal intensity that appear to correlate with the distribution of proteoglycans in the cartilage matrix. The application of these techniques may be possible in a clinical setting to enhance the detection and monitor the changes of degenerative joint disease.