Myocardial <i>T</i> ₁ mapping at 5T using multi-inversion recovery real-time spoiled GRE

<i>Objective.</i>To develop an accurate myocardial<i>T</i>₁mapping technique at 5T using Look-Locker-based multiple inversion-recovery with the real-time spoiled gradient echo (GRE) acquisition.<i>Approach.</i>The proposed<i>T</i>₁mapping technique (mIR-rt) samples the recovery of inverted magnetization using the real-time GRE and the images captured during diastole are selected for<i>T</i>₁fitting. Multiple-inversion recoveries are employed to increase the sample size for accurate fitting. The<i>T</i>₁mapping method was validated using Bloch simulation, phantom studies, and in 16 healthy volunteers at 5T.<i>Main Results.</i>In both simulation and phantom studies, the<i>T</i>₁values measured by mIR-rt closely approximate the reference<i>T</i>₁values, with errors less than 3%, while the conventional MOLLI sequence underestimates<i>T</i>₁values. The myocardial<i>T</i>₁values at 5T are 1553 ± 52 ms, 1531 ± 53 ms, and 1526 ± 60 ms (mean ± standard deviation) at the apex, middle, and base, respectively. The<i>T</i>₁values measured by MOLLI (1350 ± 48 ms, 1349 ± 47 ms, and 1354 ± 45 ms at the apex, middle, and base) were significantly lower than those of mIR-rt with<i>p</i>< 0.001 for all three layers. The mIR-rt sequence method used in our study provides high reproducibility, particularly in the middle slices, supporting its practical relevance for myocardial<i>T</i>₁mapping.<i>Significance.</i>The proposed method is feasible for myocardial<i>T</i>₁mapping at 5T and provides better accuracy than the conventional MOLLI sequence.