Free-breathing whole-heart multi-slice myocardial T1 mapping in 2 minutes.

Abstract

To develop and validate a saturation-delay-inversion recovery preparation, slice tracking and multi-slice based sequence for measuring whole-heart native T1 . The proposed free-breathing sequence performs T1 mapping of multiple left-ventricular slices by slice-interleaved acquisition to collect 10 electrocardiogram-triggered single-shot slice-selective images for each slice. A saturation-delay-inversion recovery pulse is used for T1 preparation. Prospective slice tracking by the diaphragm navigator and retrospective registration are used to reduce through-plane and in-plane motion, respectively. The proposed sequence was validated in both phantom and human subjects (12 healthy subjects and 15 patients who were referred for a clinical cardiac MR exam) and compared with saturation recovery single-shot acquisition (SASHA) and modified Look-Locker inversion recovery (MOLLI). Phantom T1 measured by the proposed sequence had excellent agreement (R2 =0.99) with the ground-truth T1 and was insensitive to heart rate. In both healthy subjects and patients, the proposed sequence yielded nine left-ventricular T1 maps per volume in less than 2 minutes (healthy volunteers: 1.8±0.4minutes; patients: 1.9±0.2minutes). The average T1 of whole left ventricle for all healthy subjects and patients were 1560±61 and 1535±49ms by SASHA, 1208±42 and 1233±56ms by MOLLI5(3)3, and 1397±34 and 1433±56ms by the proposed sequence, respectively. The corresponding coefficient of variation of T1 were 6.2±1.4% and 5.8±1.6%, 5.3±1.1% and 5.1±0.8%, and 4.9±0.8% and 4.5±0.8%, respectively. The proposed sequence enables quantification of whole heart T1 with good accuracy and precision in less than 2 minutes during free breathing.