Cartilage MRI T2 relaxation time mapping: overview and applications.

The sensitivity of magnetic resonance imaging to biochemical and biophysical changes in the extracellular matrix of articular cartilage give it the potential to noninvasively detect the earliest changes of cartilage damage. The transverse relaxation time (T2) of cartilage has been shown to be a sensitive parameter for evaluation of early degeneration in articular cartilage, particularly changes in water and collagen content and tissue anisotropy. Although initial application has been in microimaging of small cartilage explants, in vivo techniques have been developed for cartilage T2 mapping of human joints. In addition to potential application in development of new pharmaceuticals and surgical techniques for preserving cartilage, in vivo cartilage T2 mapping can improve understanding of arthritis, cartilage aging, and response of cartilage to exercise.