Reproducibility of native T1 value measurements across cardiac phases and slice positions using a 1.5T magnetic...

To assess the reproducibility of native T1 value measurements across different myocardial slice positions and cardiac phases using a 1.5T magnetic resonance (MR) system. Twenty-seven healthy male volunteers (mean age 31.2 ± 4.8 years) underwent native T1 mapping on a 1.5T MR scanner (Ingenia, Philips) using a modified look-locker inversion recovery (MOLLI) 5-(3)-3 sequence. Short-axis images were acquired at the basal, mid, and apical levels of the left ventricle during both diastolic and systolic phases. Each acquisition was repeated twice. Native T1 values were measured using semi-automated region of interest (ROI) placement with Cvi42 software. Reproducibility was evaluated using Bland-Altman analysis. Native T1 values were 982.1 ± 27.9 ms (base), 988.3 ± 21.3 ms (mid), and 993.8 ± 49.2 ms (apex) during diastole, and 981.1 ± 35.1 ms (base), 989.1 ± 24.3 ms (mid), and 984.4 ± 33.3 ms (apex) during systole. No significant differences were observed between diastolic and systolic phases or across slice positions. Bland-Altman analysis revealed the narrowest 95% limits of agreement for mid-ventricular slices in systole (- 24.8 to 22.7 ms) and the widest for apical slices in diastole (- 48.1 to 56.2 ms). Reproducibility was consistently superior during systole compared to diastole. Native myocardial T1 values at 1.5T demonstrated reproducibility across both cardiac phases and slice positions in healthy subjects. However, systolic imaging provided narrower limits of agreement, particularly at the apex. Therefore, imaging in systole is recommended for assessing apical T1 values.