In vivo 3T spiral imaging based multi-slice T1p mapping of knee cartilage in osteoarthritis

T-1p 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-1p 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-1p values decreased as agarose concentration increased. T-1p values obtained with imaging methods were compared with those obtained with spectroscopic methods. T-1p 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-1p which was 0.68% in phantoms and 4.8% in healthy volunteers. There was a significant difference (P = 0.002) in the average T-1p 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-1p and T-2; however, the difference of T-2 was not significant between controls and osteoarthritis patients. The results suggest that T-1p) relaxation times may be a promising clinical tool for osteoarthritis detection and treatment monitoring.