In vivo proton MR three-dimensional T1rho mapping of human articular cartilage: initial experience

The purpose of this study was to demonstrate the feasibility of computing three-dimensional relaxation maps of spin-lattice relaxation time in the rotating frame (T1rho) from in vivo magnetic resonance (MR) images of the human patellofemoral joint. T1rho was measured by applying a three-dimensional gradient-echo pulse sequence in six healthy subjects and one symptomatic subject by using a 1.5-T MR imager and a 15-cm-diameter transmit-receive quadrature birdcage radiofrequency coil. Average T1rho measured in healthy patellar cartilage was 49.7 msec +/- 3.2 (mean +/- SD). Two-dimensional T1rho-weighted images were obtained with a fast spin-echo pulse sequence for comparison. There was good correlation between two-dimensional and three-dimensional T1rho values for the six healthy subjects (R2 = 0.88, slope = 1.16).