Bias, Repeatability and Reproducibility of Liver T-1 Mapping With Variable Flip Angles

Background Three-dimensional variable flip angle (VFA) methods are commonly used for T-1 mapping of the liver, but there is no data on the accuracy, repeatability, and reproducibility of this technique in this organ in a multivendor setting. Purpose To measure bias, repeatability, and reproducibility of VFA T-1 mapping in the liver. Study Type Prospective observational. Population Eight healthy volunteers, four women, with no known liver disease. Field Strength/Sequence 1.5-T and 3.0-T; three-dimensional steady-state spoiled gradient echo with VFAs; Look-Locker. Assessment Traveling volunteers were scanned twice each (30 minutes to 3 months apart) on six MRI scanners from three vendors (GE Healthcare, Philips Medical Systems, and Siemens Healthineers) at two field strengths. The maximum period between the first and last scans among all volunteers was 9 months. Volunteers were instructed to abstain from alcohol intake for at least 72 hours prior to each scan and avoid high cholesterol foods on the day of the scan. Statistical Tests Repeated measures ANOVA, Student t-test, Levene's test of variances, and 95% significance level. The percent error relative to literature liver T-1 in healthy volunteers was used to assess bias. The relative error (RE) due to intrascanner and interscanner variation in T-1 measurements was used to assess repeatability and reproducibility. Results The 95% confidence interval (CI) on the mean bias and mean repeatability RE of VFA T-1 in the healthy liver was 34 +/- 6% and 10 +/- 3%, respectively. The 95% CI on the mean reproducibility RE at 1.5 T and 3.0 T was 29 +/- 7% and 25 +/- 4%, respectively. Data Conclusion Bias, repeatability, and reproducibility of VFA T-1 mapping in the liver in a multivendor setting are similar to those reported for breast, prostate, and brain. Level of Evidence 1 Technical Efficacy Stage 1