Segmented Look-Locker With Inversion Efficiency Correction (SELLIE) for Accurate and Precise Cardiac T₁ Mapping in...

The purpose of this study was to develop a multislice, segmented electrocardiogram (ECG)-triggered, respiration-gated Look-Locker T₁ mapping sequence with inversion efficiency (IE) correction, optimized for high-field MRI. The segmented Look-Locker with inversion efficiency correction (SELLIE) was validated in phantom and in vivo studies using an agarose/NiCl₂ phantom, 5 healthy rats, 23 aortic-banding rats, and 7 sham-operated rats. The accuracy, precision, and repeatability of SELLIE were compared with the conventional Look-Locker technique without IE correction using Pearson correlation analysis and the Kruskal-Wallis H test. In the phantom experiments, SELLIE demonstrated significantly improved accuracy (T₁ estimation error: 0.80 ± 1.17%) compared with the uncorrected Look-Locker method (3.70 ± 1.12%). Additionally, SELLIE showed superior precision (coefficient of variation: 0.71 ± 0.35%) relative to the uncorrected method (1.15 ± 0.39%). In vivo experiments with healthy rats showed good precision for both SELLIE (1.70 ± 0.61%) and the uncorrected technique (1.04 ± 0.49%). In the sham and aortic-banding rats, T₁ values from SELLIE correlated strongly with the end-diastolic pressure-volume relationship (EDPVR) (r = 0.57, p = 0.001), outperforming the uncorrected method (r = 0.37, p = 0.04). The mean myocardium native T₁ times of the sham rats (~17 weeks old) from the uncorrected Look-Locker was 1567 ± 32 ms, whereas the mean myocardium T₁ times from SELLIE was 1723 ± 47 ms. In conclusion, SELLIE provides accurate and precise T₁ mapping for high-field MRI, correcting inversion pulse imperfections. This technique enables reliable longitudinal scanning and comparison across animal models.