Simultaneous Mapping of T1 and T2 Using Cardiac Magnetic Resonance Fingerprinting in a Cohort of Healthy Subjects at 1.5T

Background Cardiac MR fingerprinting (cMRF) is a novel technique for simultaneous T-1 and T-2 mapping. Purpose To compare T-1/T-2 measurements, repeatability, and map quality between cMRF and standard mapping techniques in healthy subjects. Study Type Prospective. Population In all, 58 subjects (ages 18-60). Field Strength/Sequence cMRF, modified Look-Locker inversion recovery (MOLLI), and T-2-prepared balanced steady-state free precession (bSSFP) at 1.5T. Assessment T-1/T-2 values were measured in 16 myocardial segments at apical, medial, and basal slice positions. Test-retest and intrareader repeatability were assessed for the medial slice. cMRF and conventional mapping sequences were compared using ordinal and two alternative forced choice (2AFC) ratings. Statistical Tests Paired t-tests, Bland-Altman analyses, intraclass correlation coefficient (ICC), linear regression, one-way analysis of variance (ANOVA), and binomial tests. Results Average T-1 measurements were: basal 1007.4 +/- 96.5 msec (cMRF), 990.0 +/- 45.3 msec (MOLLI); medial 995.0 +/- 101.7 msec (cMRF), 995.6 +/- 59.7 msec (MOLLI); apical 1006.6 +/- 111.2 msec (cMRF); and 981.6 +/- 87.6 msec (MOLLI). Average T-2 measurements were: basal 40.9 +/- 7.0 msec (cMRF), 46.1 +/- 3.5 msec (bSSFP); medial 41.0 +/- 6.4 msec (cMRF), 47.4 +/- 4.1 msec (bSSFP); apical 43.5 +/- 6.7 msec (cMRF), 48.0 +/- 4.0 msec (bSSFP). A statistically significant bias (cMRF T-1 larger than MOLLI T-1) was observed in basal (17.4 msec) and apical (25.0 msec) slices. For T-2, a statistically significant bias (cMRF lower than bSSFP) was observed for basal (-5.2 msec), medial (-6.3 msec), and apical (-4.5 msec) slices. Precision was lower for cMRF-the average of the standard deviation measured within each slice was 102 msec for cMRF vs. 61 msec for MOLLI T-1, and 6.4 msec for cMRF vs. 4.0 msec for bSSFP T-2. cMRF and conventional techniques had similar test-retest repeatability as quantified by ICC (0.87 cMRF vs. 0.84 MOLLI for T-1; 0.85 cMRF vs. 0.85 bSSFP for T-2). In the ordinal image quality comparison, cMRF maps scored higher than conventional sequences for both T-1 (all five features) and T-2 (four features). Data Conclusion This work reports on myocardial T-1/T-2 measurements in healthy subjects using cMRF and standard mapping sequences. cMRF had slightly lower precision, similar test-retest and intrareader repeatability, and higher scores for map quality. Evidence Level 2 Technical Efficacy Stage 1