T2 and T2* Mapping

Abstract

New noninvasive biochemical quantitative magnetic resonance imaging (MRI) techniques are increasingly applied in cartilage repair and osteoarthritis (OA), where quantitative T2 mapping and initially also T2* mapping are seen as valid biomarkers. These quantitative MR biomarkers detect early degeneration of articular cartilage, mainly represented by increasing water content and a disruption of the collagen network. Recently, feasibility of biochemical MR imaging of repair tissue and the surrounding cartilage after cartilage repair procedures has been demonstrated. Different ultrastructural properties of the repair tissue after different repair procedures, such as microfracturing and autologous chondrocyte implantation, resulted in differences in imaging characteristics. Further, these biochemical imaging characteristics varied during follow-up and are able to depict repair tissue maturation. Within these approaches, zonal stratification analysis was considered crucial. Comparably in OA, T2 mapping seems to provide additional information during different stages of cartilage degeneration and can be used in patient subgroups as a predictor for disease progression. Although the results in various studies employing T2 and T2* mapping are very promising and valuable additional information on cartilage ultrastructure can be obtained, (comparable to all the other quantitative cartilage imaging techniques) further multimodal investigation is needed especially since a standard of reference is hard to define.