Cartilage T1ρ and T2 relaxation times: longitudinal reproducibility and variations using different coils, MR systems and sites

Objective: To evaluate the longitudinal reproducibility and variations of cartilage T-1 rho and T-2 measurements using different coils, MR systems and sites. Methods: Single-Site study: Phantom data were collected monthly for up to 29 months on four GE 3T MR systems. Data from phantoms and human subjects were collected on two MR systems using the same model of coil; and were collected on one MR system using two models of coils. Multi-site study: Three participating sites used the same model of MR systems and coils, and identical imaging protocols. Phantom data were collected monthly. Human subjects were scanned and rescanned on the same day at each site. Two traveling human subjects were scanned at all three sites. Results: Single-Site Study: The phantom longitudinal RMS-CVs ranged from 1.8% to 2.7% for T-1 rho and 1.8-2.8% for T-2. Significant differences were found in T-1 rho and T-2 values using different MR systems and coils. Multi-Site Study: The phantom longitudinal RMS-CVs ranged from 1.3% to 2.6% for T-1 rho and 1.2-2.7% for T-2. Across three sites (n = 16), the in vivo scan-rescan RMS-CV was 3.1% and 4.0% for T-1 rho and T-2, respectively. Phantom T-1 rho and T-2 values were significantly different between three sites but highly correlated (R > 0.99). No significant difference was found in T-1 rho and T-2 values of traveling controls, with cross-site RMS-CV as 4.9% and 4.4% for T-1 rho and T-2, respectively. Conclusion: With careful quality control and cross-calibration, quantitative MRI can be readily applied in multi-site studies and clinical trials for evaluating cartilage degeneration. (C) 2015 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.