• Yoojin Lee, Martina F Callaghan, Julio Acosta-Cabronero, Antoine Lutti, and Zoltan Nagy.
• Laboratory for Social and Neural Systems Research, University of Zurich, Zürich, Switzerland.
• Magn Reson Med. 2019 Jan 1; 81 (1): 454-465.

PurposeParametric imaging methods (e.g., T1 relaxation time mapping) have been shown to be more reproducible across time and vendors than weighted (e.g., T1 -weighted) images. The purpose of this work was to more extensively evaluate the validity of this assertion.MethodsSeven volunteers underwent twice-repeated acquisitions of variable flip-angle T1 mapping, including B1 + calibration, on a 3T Philips Achieva and 3T Siemens Trio scanner. Intra-scanner and inter-vendor T1 variability were calculated. To determine T1 reproducibility levels in longitudinal settings, or after changing hardware or software, four additional data sets were acquired from two of the participants; one participant was scanned on a different 3T Siemens Trio scanner and another on the same 3T Philips Achieva scanner but after a software upgrade.ResultsIntra-scanner variability of voxel-wise T1 values was consistent between the two vendors, averaging 0.7/0.7/1.3/1.4% in white matter/cortical gray matter/subcortical gray matter/cerebellum, respectively. We observed, however, a systematic bias between the two vendors of https://doi.org/10.0/7.8/8.6/10.0%, respectively. The T1 bias across two scanners of the same model was greater than intra-scanner variability, although still only at 1.4/1.0/1.9/2.3%, respectively. A greater bias was identified for data sets acquired before/after software upgrade in white matter/cortical gray matter (3.6/2.7%) whereas variability in subcortical gray matter/cerebellum was comparable (1.7/1.9%).ConclusionWe established intra- and inter-vendor reproducibility levels for a widely used T1 mapping protocol. We anticipate that these results will guide the design of multi-center studies, particularly those encompassing multiple vendors. Furthermore, this baseline level of reproducibility should be established or surpassed during the piloting phase of such studies.© 2018 International Society for Magnetic Resonance in Medicine.

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