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T(1rho) describes the spin-lattice relaxation in the rotating frame and has been proposed for detecting damage to the cartilage collagen-proteoglycan matrix in osteoarthritis. In this study, a multi-slice T(1rho) imaging method for knee cartilage was developed using spin-lock techniques and a spiral imaging sequence. The adverse effect of T(1) regrowth during the multi-slice acquisition was eliminated by RF cycling. Agarose phantoms with different concentrations, 10 healthy volunteers, and 9 osteoarthritis patients were scanned at 3T. T(1rho) values decreased as agarose concentration increased. T(1rho) values obtained with imaging methods were compared with those obtained with spectroscopic methods. T(1rho) values obtained during multi-slice acquisition were validated with those obtained in a single slice acquisition. Reproducibility was assessed using the average coefficient of variation of median T(1rho), which was 0.68% in phantoms and 4.8% in healthy volunteers. There was a significant difference (P = 0.002) in the average T(1rho) within patellar and femoral cartilage between controls (45.04 +/- 2.59 ms) and osteoarthritis patients (53.06 +/- 4.60 ms). A significant correlation was found between T(1rho) and T(2); however, the difference of T(2) was not significant between controls and osteoarthritis patients. The results suggest that T(1rho) relaxation times may be a promising clinical tool for osteoarthritis detection and treatment monitoring.
Li et al. (Fri,) studied this question.