Quantitative MR of Cartilage and Implications for TMJ Imaging

Conventional MR images are qualitative and rely on subjective interpretation of changes in tissue appearance to diagnose injury or disease. Several inherent tissue properties contribute to a tissue's appearance in an MR image. These properties include the tissue's T1 time, T2 time, and proton density. Specific MR pulse sequences are designed to generate image contrast based on these inherent properties, creating T1weighted, T2-weighted, or proton density-weighted images, respectively. Depending on the tissue of interest and underlying disease process, these images can be used to qualitatively assess a tissue for the presence of pathology. With respect to cartilage of the TMJ and other joints, conventional MR images are limited to detecting morphological changes, such as thinning or loss, of the articular cartilage. Once cartilage loss is detectable by conventional MR, the joint has already experienced irreversible changes leading toward osteoarthritis.