Repeatability and Reproducibility of 3D MR Fingerprinting Relaxometry Measurements in Normal Breast Tissue.

Background The 3D breast magnetic resonance fingerprinting (MRF) technique enables T-1 and T-2 mapping in breast tissues. Combined repeatability and reproducibility studies on breast T-1 and T-2 relaxometry are lacking. Purpose To assess test-retest and two-visit repeatability and interscanner reproducibility of the 3D breast MRF technique in a single-institution setting. Study Type Prospective. Subjects Eighteen women (median age 29 years, range, 22-33 years) underwent Visit 1 scans on scanner 1. Ten of these women underwent test-retest scan repositioning after a 10-minute interval. Thirteen women had Visit 2 scans within 7-15 days in same menstrual cycle. The remaining five women had Visit 2 scans in the same menstrual phase in next menstrual cycle. Five women were also scanned on scanner 2 at both visits for interscanner reproducibility. Field Strength/Sequence Two 3T MR scanners with the 3D breast MRF technique. Assessment T-1 and T-2 MRF maps of both breasts. Statistical Tests Mean T-1 and T-2 values for normal fibroglandular tissues were quantified at all scans. For variability, between and within-subjects coefficients of variation (bCV and wCV, respectively) were assessed. Repeatability was assessed with Bland-Altman analysis and coefficient of repeatability (CR). Reproducibility was assessed with interscanner coefficient of variation (CoV) and Wilcoxon signed-rank test. Results The bCV at test-retest scans was 9-12% for T-1, 7-17% for T-2, wCV was <4% for T-1, and <7% for T-2. For two visits in same menstrual cycle, bCV was 10-15% for T-1, 13-17% for T-2, wCV was <7% for T-1 and <5% for T-2. For two visits in the same menstrual phase, bCV was 6-14% for T-1, 15-18% for T-2, wCV was <7% for T-1, and <9% for T-2. For test-retest scans, CR for T-1 and T-2 were 130 msec and 11 msec. For two visit scans, CR was <290 msec for T-1 and 10-14 msec for T-2. Interscanner CoV was 3.3-3.6% for T-1 and 5.1-6.6% for T-2, with no differences between interscanner measurements (P = 1.00 for T-1, P = 0.344 for T-2). Data Conclusion 3D breast MRF measurements are repeatable across scan timings and scanners and may be useful in clinical applications in breast imaging. Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:1133-1143.