Multi-site, multi-platform comparison of MRI T(1) measurement using the system phantom

Recent innovations in quantitative magnetic resonance imaging (MRI) measurement methods have led to improvements in accuracy, repeatability, and acquisition speed, and have prompted renewed interest to reevaluate the medical value of quantitative T(1). The purpose of this study was to determine the bias and reproducibility of T(1) measurements in a variety of MRI systems with an eye toward assessing the feasibility of applying diagnostic threshold T(1) measurement across multiple clinical sites. We used the International Society of Magnetic Resonance in Medicine/National Institute of Standards and Technology (ISMRM/NIST) system phantom to assess variations of T(1) measurements, using a slow, reference standard inversion recovery sequence and a rapid, commonly-available variable flip angle sequence, across MRI systems at 1.5 tesla (T) (two vendors, with number of MRI systems n = 9) and 3 T (three vendors, n = 18). We compared the T(1) measurements from inversion recovery and variable flip angle scans to ISMRM/NIST phantom reference values using Analysis of Variance (ANOVA) to test for statistical differences between T(1) measurements grouped according to MRI scanner manufacturers and/or static field strengths. The inversion recovery method had minor over- and under-estimations compared to the NMR-measured T(1) values at both 1.5 T and 3 T. Variable flip angle measurements had substantially greater deviations from the NMR-measured T(1) values than the inversion recovery measurements. At 3 T, the measured variable flip angle T(1) for one vendor is significantly different than the other two vendors for most of the samples throughout the clinically relevant range of T(1). There was no consistent pattern of discrepancy between vendors. We suggest establishing rigorous quality control procedures for validating quantitative MRI methods to promote confidence and stability in associated measurement techniques and to enable translation of diagnostic threshold from the research center to the entire clinical community.