T2 relaxation time measurements in osteoarthritis

Quantification of changes in T2 relaxation time, in human cartilage, with progression of osteoarthritis (OA), and evaluation of qualitative correlations with clinical evaluation, histology and polarized light microscopy (PLM). Cartilage-bone plugs were harvested from fresh cadaveric knees (n = 10) and specimens after surgical knee replacement (n = 2) at 12 locations, including lateral and medial sides of tibia, femora and patella. Magnetic resonance imaging was performed at 1.5 Tesla using a.2D spin echo sequence. Histological slices were assessed for OA severity through a grading scale based on combined histological and PLM results. T2 values in clinically moderate OA were generally higher than in severe OA and normal cartilage. Significant association was established between normal and early OA subjects and T2 variation, in the medial compartment of the knee (p < 0.05) but especially in the medial tibial cartilage (p < 0.00005). As expected, medial and lateral tibio-femoral compartments underwent more severe degeneration. Additionally, there were intracompartmental variation of the relaxation times and histological patterns, which demonstrate the underlying focal involvement of OA in the knee. Furthermore, T2 values reflected OA pathogenesis with a positive correlation with histology grading scale. Finally, increased T2 is correlated to histological degeneration of cartilage and may be a good marker for early OA in tibial articular cartilage.