Background: T2 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 T2 mapping, using various MRI equipment and acquisition protocols. Methods: In this prospective multicenter study, four traveling, healthy human subjects underwent T2 mapping twice at five different centers with a 6-month-interval. Centers had various MRI scanners, field strengths, and T2 mapping acquisition protocols. Mean T2 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 T2 values across centers, ANOVA was performed. Results: ICCs of the T2 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 T2values were observed across centers, both in vivo and in the phantom. Conclusions: The results of this study suggest that T2mapping can be used to longitudinal assess cartilage degeneration in multicenter studies. Given the differences in absolute cartilage T2values across centers, absolute T2values derived from various centers in multicenter multivendor trials should not be pooled.

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Quantitative Imaging in Medicine and Surgery
Department of Radiology

Verschueren, J. (Joost), Eijgenraam, S.M. (Susanne M.), Klein, S., Poot, D., Bierma-Zeinstra, S., Tamames, J.A.H. (Juan A. Hernandez), … Oei, E. (2021). T2mapping of healthy knee cartilage: Multicenter multivendor reproducibility. Quantitative Imaging in Medicine and Surgery, 11(4), 1247–1255. doi:10.21037/qims-20-674