Fast myocardial T 1 mapping using shortened inversion recovery based schemes

Background Myocardial T 1 mapping shows promise for assessment of cardiomyopathies. Most myocardial T 1 mapping techniques, such as modified Look–Locker inversion recovery (MOLLI), generate one T 1 map per breath‐held acquisition (9–17 heartbeats), which prolongs multislice protocols and may be unsuitable for patients with breath‐holding difficulties. Purpose To develop and characterize novel shortened inversion recovery based T 1 mapping schemes of 2–5 heartbeats. Study Type Prospective. Population/Phantom Numerical simulations, agarose/NiCl 2 phantom, 16 healthy volunteers, and 24 patients. Field Strength/Sequence 1.5T/MOLLI. Assessment All shortened T 1 mapping schemes were characterized and compared with a conventional MOLLI scheme (5‐(3)‐3) in terms of accuracy, precision, spatial variability, and repeatability. Statistical Tests Kruskal–Wallis, Wilcoxon rank sum tests, analysis of variance, Student's t ‐tests, Bland–Altman analysis, and Pearson correlation analysis. Results All shortened schemes provided limited T 1 time variations (≤2% for T 1 times ≤1200 msec) and limited penalty of precision (by a factor of ~1.4–1.5) when compared with MOLLI in numerical simulations. In phantom, differences between all schemes in terms of accuracy, spatial variability, and repeatability did not reach statistical significance ( P > 0.71). In healthy volunteers, there were no statistically significant differences between all schemes in terms of native T 1 times and repeatability for myocardium ( P = 0.21 and P = 0.87, respectively) and blood ( P = 0.79 and P = 0.41, respectively). All shortened schemes led to a limited increase of spatial variability for native myocardial T 1 mapping with respect to MOLLI (by a factor of 1.2) ( P < 0.0001). In both healthy volunteers and patients, the two‐heartbeat scheme and MOLLI led to highly linearly correlated T 1 times (correlation coefficients ≥0.83). Data Conclusion The proposed two‐heartbeat T 1 mapping scheme yields a 5‐fold acceleration compared with MOLLI, with highly linearly correlated T 1 times, no significant difference of repeatability, and limited spatial variability penalty at 1.5T. This approach may enable myocardial T 1 mapping in patients with severe breath‐holding difficulties and reduce the examination time of multislice protocols. Level of Evidence : 1 Technical Efficacy Stage : 3 J. Magn. Reson. Imaging 2019;50:641–654.