ABSTRACT: To quantify the precision of in vivo cardiac DTI (cDTI) acquired with a spin echo, first- and second-order motion-compensated (M1 M2 ), convex optimized diffusion encoding (CODE) sequence.Free-breathing CODE-M1 M2 cDTI were acquired in healthy volunteers (N?=?10) at midsystole and diastole with 10 repeated acquisitions per phase. 95% confidence intervals of uncertainty in reconstructed diffusion tensor eigenvectors ( E?1, E?2, E?3), mean diffusivity (MD), fractional anisotropy (FA), and tensor Mode were measured using a bootstrapping approach. Trends in observed tensor metric uncertainty were evaluated as a function of scan duration, image SNR, cardiac phase, and bulk motion artifacts.For midsystolic scans including 5 signal averages (scan time: ?5?min), the median myocardial 95% confidence intervals of uncertainties were: E?1: 15.5?±?1.2°, E?2: 31.2?±?3.5°, E?3: 21.8?±?3.1°, MD: 0.38?±?0.02?×?10-3 mm2 /s, FA: 0.20?±?0.01, and Mode: 1.10?±?0.08. Uncertainty in all parameters increased for diastolic scans: E?1: 31.9?±?7.1°, E?2: 59.6?±?6.8°, E?3 : 40.5?±?6.4°, MD: 0.52?±?0.09?×?10-3 mm2 /s, FA: 0.23?±?0.01, and Mode: 1.57?±?0.11. Diastolic cDTI also reported higher MD (MDDIA ?=?1.91?±?0.34?×?10-3 mm2 /s vs. MDSYS ?=?1.58?±?0.09?×?10-3 mm2 /s, P?= 8?×?10-3 ) and lower FA values (FADIA ?=?0.32?±?0.06 vs. FASYS ?=?0.37?±?0.03, P?=?0.03) .cDTI precision improved with increasing nondiffusion-weighted (b?=?0) image SNR, but gains were minimal for SNR???25 (?10 averages). cDTI precision was also sensitive to intershot bulk motion artifacts, which led to better precision for midsystolic imaging.
