Abstract
BACKGROUND: T(2) mapping is increasingly used to quantify cartilage degeneration in knee osteoarthritis (OA), yet reproducibility studies in a multicenter setting are limited. The purpose of this study was to determine the longitudinal reproducibility and multicenter variation of cartilage T(2) mapping, using various MRI equipment and acquisition protocols. METHODS: In this prospective multicenter study, four traveling, healthy human subjects underwent T(2) mapping twice at five different centers with a 6-month-interval. Centers had various MRI scanners, field strengths, and T(2) mapping acquisition protocols. Mean T(2) values were calculated in six cartilage regions of interest (ROIs) as well as an average value per patient. A phantom was scanned once at each center. To evaluate longitudinal reproducibility, intraclass correlation coefficients (ICC), root-mean-square coefficient of variation (RMS-CV), and a Bland-Altman plot were used. To assess the variation of in vivo and phantom T(2) values across centers, ANOVA was performed. RESULTS: ICCs of the T(2) mapping measurements per ROI and the ROI's combined ranged from 0.73 to 0.91, indicating good to excellent longitudinal reproducibility. RMS-CVs ranged from 1.1% to 1.5% (per ROI) and 0.6% to 1.6% (ROIs combined) across the centers. A Bland-Altman plot did not reveal a systematic error. Evident, but consistent, discrepancies in T(2) values were observed across centers, both in vivo and in the phantom. CONCLUSIONS: The results of this study suggest that T(2) mapping can be used to longitudinal assess cartilage degeneration in multicenter studies. Given the differences in absolute cartilage T(2) values across centers, absolute T(2) values derived from various centers in multicenter multivendor trials should not be pooled.