Background: Articular cartilage plays a critical biomechanical function in physiological activities of joints, owing
to the unique biochemical structures of the tissue. In osteoarthritis, cartilage irreversibly loses its integrity in extracellular
matrix organization followed by enzymatic degradation, leading to the deterioration in joint function. Often surgical
interventions with implantation of autologous chondrocytes or engineered cartilage tissue, a promising alternative, are
necessary to restore cartilage function. Therefore, non-invasively assessing and monitoring the outcomes of repair surgeries
is an important issue for cartilage regeneration. Quantitative MRI methods show great promise in assessing the extent
of the repair and elucidating information on the biochemical composition of the repair cartilage.
Methods: PubMed and Web of Science searches were run on queries related to MR imaging of healthy, diseased and regenerated
cartilage in human, animal and in vitro studies. The results were synthesized to highlight key themes in current
technologies and future directions.
Results: Three imaging techniques emerged as the most widely studied: T2 imaging, gadolinium enhanced T1 (T1Gd) imaging
and diffusion imaging. T2 imaging can be used to determine if the zonal architecture of cartilage has been replicated
by the repair tissue, T1Gd is widely utilized to quantify the amount of proteoglycans in the repair tissue, and diffusion imaging
can quantify the direction and magnitude of the mobility of water molecules through the cartilage.
Conclusion: Quantitative MRI shows great promise as a non-invasive measure of regenerated cartilage health. Studies are
more successful when they combine multiple modalities to achieve a multi-parametric view of cartilage properties. Taken
together, T2, T1Gd and diffusion imaging have great potential to accurately assess the success of cartilage regeneration and