Establishing intra‐ and inter‐vendor reproducibility of T₁ relaxation time measurements with 3T MRI

Purpose Parametric imaging methods (e.g., T 1 relaxation time mapping) have been shown to be more reproducible across time and vendors than weighted (e.g., T 1 ‐weighted) images. The purpose of this work was to more extensively evaluate the validity of this assertion. Methods Seven volunteers underwent twice‐repeated acquisitions of variable flip‐angle T 1 mapping, including B 1 + calibration, on a 3T Philips Achieva and 3T Siemens Trio scanner. Intra‐scanner and inter‐vendor T 1 variability were calculated. To determine T 1 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. Results Intra‐scanner variability of voxel‐wise T 1 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 T 1 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%). Conclusion We established intra‐ and inter‐vendor reproducibility levels for a widely used T 1 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.