Myocardial native T1 and extracellular volume measurements at 5T: Feasibility study and initial experience.

Background: T1 mapping is a robust and highly reproducible technique for quantitative assessment of cardiomyopathy. The aim of this study is to investigate the feasibility of 5T myocardial T1 mapping and to establish preliminary reference values for myocardial T1 at 5T.

Methods: Twenty-eight healthy volunteers (median age, 42 [interquartile range (IQR): 29-54] years; 14 male) and 11 patients (median age, 44 [IQR: 34-51] years; 7 male) underwent cardiovascular magnetic resonance at 5T. T1 mapping was acquired using a motion-corrected modified Look-Locker inversion recovery sequence [5(3)3 scheme for pre-contrast, (4(1)3(1)2) scheme for post-contrast] in three short-axis planes (base, middle, and apex). T1 values were quantified per segment, per slice, and globally.

Results: Healthy volunteers had a mean global native T1 value of 1506.2 ± 41.7 ms, with T1 values decreasing progressively from the base to the apex slice (P = 0.08). Significantly higher T1 values were revealed in the septum compared to the non-septal myocardium (1540.1 ± 69.3 vs 1477.6 ± 93.7, P < 0.001). No statistically significant gender- and age-related differences were observed in native T1 values (both, P > 0.05). Within the spectrum of cardiac pathologies analyzed in this study, patients exhibited higher native T1 values (1638.7 ± 108.6 ms vs 1506.2 ± 41.7 ms, P < 0.001) and higher extracellular volume fraction (37.5% ± 5.5% vs 29.5% ± 2.1%, P = 0.074) compared to healthy volunteers, late gadolinium enhancement (LGE)-positive segments exhibited significantly higher T1 values than LGE-negative segments (1685.2 ± 144.1 vs 1582.6 ± 88.7, P < 0.001). There was excellent intra-scanner test-retest, intra-observer, and inter-observer reproducibility for measurement of native T1.

Conclusion: The present study demonstrated the feasibility of T1 mapping quantification at 5T and presented mean native T1 values in healthy human myocardium at this field strength, which can be used as reference values specific for this magnetic resonance setting.