Myocardial T1 and T2 Mapping at 5.0T: Feasibility and Comparison with 3.0-T MRI

BACKGROUND: Myocardial T1 and T2 mapping provide a non-invasive quantitative assessment of cardiac tissue. While established at 1.5-T and 3.0-T MRI, the mapping performance and reference values at 5.0-T MRI remain to be investigated. This study aims to evaluate the feasibility and establish reference values for cardiac T1 and T2 mapping at 5.0-T MRI in healthy subjects. METHODS: In this prospective study, 50 healthy volunteers underwent cardiovascular magnetic resonance at both 3.0-T and 5.0-T systems from February to April 2025. Mapping protocols included MOdified Look Locker Inversion recovery (MOLLI, T1), T2-prepared gradient-echo (T2-prep-GRE, T2), and a simultaneous multi-parametric mapping technique (Multimap, T1 and T2). At 3.0-T MRI, both balanced steady-state free precession (bSSFP) and fast low-angle shot (FLASH) readouts were employed, while only the FLASH readout was used at 5.0-T MRI. Segment exclusion rates were analyzed at the subject-level using nonparametric tests with Holm correction for multiple comparisons. Measurement repeatability (intra-observer, scan-rescan) and reproducibility (inter-observer) were assessed by coefficient of variation (CoV), repeatability coefficient (RC), and intraclass correlation coefficient (ICC). Systematic difference and agreement between repeated measurements were evaluated using Bland-Altman analysis. Group-level variability was described by mean ± SD across subjects. Group comparisons were performed with repeated measures ANOVA. RESULTS: All techniques at 5.0-T MRI yielded high-quality images that were predominantly free of visible artifacts with the FLASH readout. After quality control, segment acceptance rates ranged from 87.8% to 94.0%, and matched FLASH-readout comparisons showed higher exclusion rates at 5.0T than at 3.0T (all P < 0.001). Native T1 values were significantly higher at 5.0T than at 3.0-T MRI (MOLLI: 1452.9 ± 33.2 ms vs. 1305.9 ± 38.3 ms, P < 0.0001), while T2 values were significantly lower (T2-prep-GRE: 37.53 ± 1.74 ms vs. 43.97 ± 2.95 ms, P < 0.0001). Scan-rescan repeatability at 5.0-T (ICC: 0.87-0.92; CoV: 1.25%-2.17%; RC: 3.45%-6.01%) was comparable to 3.0-T MRI. Measurement precision, as assessed by CoV, RC, and ICC, was higher for 5.0-T than 3.0-T with FLASH, and lower than bSSFP-based techniques. Multimap enabled efficient, simultaneous T1 and T2 quantification with acceptable reproducibility at 5.0-T. CONCLUSION: Myocardial T1 and T2 mapping at 5.0-T MRI are reliable and reproducible in healthy individuals, offering reference values for normal myocardium at this field strength. The good measurement reproducibility and precision of 5.0-T cardiac mapping support its clinical potential for myocardial tissue characterization.