• Benoit Combès, Laureline Monteau, Elise Bannier, Virginie Callot, Pierre Labauge, Xavier Ayrignac, Clarisse Carra Dallière, Jean Pelletier, Adil Maarouf, Jerome de Seze, Nicolas Collongues, Christian Barillot, Gilles Edan, Jean Christophe Ferré, Anne Kerbrat, and EMISEP study group.
• Univ Rennes, Inria, CNRS, Inserm, IRISA UMR 6074, Visages, U1128, France.
• J Magn Reson Imaging. 2019 Jun 1; 49 (6): 1777-1785.

BackgroundAssessing the multicenter variability of magnetization transfer ratio (MTR) measurements in the spinal cord of healthy controls is the first step toward investigating its clinical use as a biomarker.PurposeTo analyze the between-session, between-participant, and between-scanner variability of MTR measurements in automatically extracted regions of interest in the cervical cord of healthy controls.Study TypeControl study.PopulationForty-four participants, distributed across five MRI scanners (all from the same manufacturer). Ten participants were scanned twice in the same scanner, and 10 others were scanned twice in two different scanners.Field Strength/Sequence3D-gradient echo images, centered on C5, without and with magnetization transfer prepulse at 3T.AssessmentWe calculated the mean MTR for different vertebral levels in the whole cord (WC), as well as in the white matter and gray matter, and determined the between-session, between-participant, and between-scanner variabilities.Statistical TestsCoefficients of variation and intraclass correlations (ICCs) for the different variabilities and their associated confidence intervals.ResultsThe MTR measurements for Levels C4-C6 (near the slab center) exhibited a mean value in WC of 34.6 pu and a pooled standard deviation of 0.9 pu. The between-session coefficient of variation was estimated as 2.3% (ICC = 0.63), the between-participant coefficient as 1.6% (ICC = 0.32), and the between-scanner coefficient as 0.7% (ICC = 0.05). The resulting aggregate coefficient of variation was 2.9%, which was sufficiently low to detect an MTR reduction of 1 pu between groups of about 45 participants (Type-I error rate: 0.05; Type-II error rate: 0.10).Data ConclusionThe good between-scanner reproducibility and low overall variability in cervical spinal cord MTR measurements in a control population might pave the way for multicenter analyses in various neurological diseases with moderate cohort sizes.Level Of Evidence2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:1777-1785.© 2018 International Society for Magnetic Resonance in Medicine.

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