Myocardial T ₁ mapping at 5T using multi-inversion recovery real-time spoiled GRE

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