Single breath‐hold three‐dimensional whole‐heart T2 mapping with low‐rank plus sparse reconstruction

Abstract The purpose of the current study was to develop and evaluate a three‐dimensional single Breath‐hOLd cardiac T 2 mapping sequence (3D BOLT) with low‐rank plus sparse (L + S) reconstruction for rapid whole‐heart T 2 measurement. 3D BOLT collects three highly accelerated electrocardiogram‐triggered volumes with whole‐heart coverage, all within a single 12‐heartbeat breath‐hold. Saturation pulses are performed every heartbeat to prepare longitudinal magnetization before T 2 preparation (T 2 ‐prep) or readout, and the echo time of T 2 ‐prep is varied per volume for variable T 2 weighting. Accelerated volumes are reconstructed jointly by an L + S algorithm. 3D BOLT was optimized and validated against gradient spin echo (GraSE) and a previously published approach (three‐dimensional free‐breathing cardiac T 2 mapping [3DFBT2]) in both phantoms and human subjects (11 healthy subjects and 10 patients). The repeatability of 3D BOLT was validated on healthy subjects. Retrospective experiments indicated that 3D BOLT with 4.2‐fold acceleration achieved T 2 measurements comparable with those obtained with fully sampled data. T 2 measured in phantoms using 3D BOLT demonstrated good accuracy and precision compared with the reference (R 2 > 0.99). All in vivo imaging was successful and the average left ventricle T 2 s measured by GraSE, 3DFBT2, and 3D BOLT were comparable and consistent for all healthy subjects (47.0 ± 2.3 vs. 47.7 ± 2.7 vs. 48.4 ± 1.8 ms) and patients (50.8 ± 3.0 vs. 48.6 ± 3.9 vs. 49.1 ± 3.7 ms), respectively. Myocardial T 2 measured by 3D BOLT had excellent agreement with 3DFBT2 and there was no significant difference in mean, standard deviation, and coefficient of variation. 3D BOLT showed excellent repeatability (intraclass correlation coefficient: 0.938). The proposed 3D BOLT achieved whole‐heart T 2 mapping in a single breath‐hold with good accuracy, precision, and repeatability on T 2 measurements.