T2* mapping of articular cartilage: current status of research and first clinical applications.
T2* mapping is a relatively new method for the compositional assessment of the articular cartilage. Typically, a multigradient echo or an ultrashort echo time imaging technique with a range of short and very short echo times is used. In most studies, imaging is performed at a high field strength, that is, 3 and 7 T. Postprocessing includes exponential fitting of relaxation decay and manual region-of-interest-based measurements of T2* times on T2* maps. Detailed analyses of T2* times of articular cartilage have shown distinct T2* components with shorter and longer T2* times. Moreover, there is a zonal distribution with a significant depthwise gradient of T2*, with relatively short times near the osteochondral junction and relatively long times at the cartilage's surface. T2* times of normal articular cartilage at the knee are, when averaged over the whole cartilage thickness and using monoexponential fitting, approximately 20 milliseconds. The results of recent studies have shown a good test-retest as well as interreader and intrareader reliabilities for T2* mapping. This article provides a descriptive review of the current literature, briefly discusses the technique itself, and provides an outlook on future research questions and possible clinical applications.
From the *Department of Radiology, University Hospital Zurich; and †Institute for Biomedical Engineering, University and ETH Zurich, Zürich, Switzerland.
Gustav
G
Andreisek
Markus
M
Weiger
D002357:Cartilage Diseases / Q000473:pathology*; D002358:Cartilage, Articular / Q000293:injuries* / Q000473:pathology*; D019317:Evidence-Based Medicine; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007592:Joint Diseases / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*