Fast cardiac T1ρ,adiab mapping using slice‐selective adiabatic spin‐lock preparation pulses

Abstract

AbstractPurposeMyocardial T1ρ mapping techniques commonly acquire multiple images in one breathhold to calculate a single‐slice T1ρ map. Recently, non‐selective adiabatic pulses have been used for robust spin‐lock preparation (T1ρ,adiab). The objective of this study was to develop a fast multi‐slice myocardial T1ρ,adiab mapping approach.MethodsThe proposed‐sequence reduces the number of breathholds required for whole‐heart 2D T1ρ,adiab mapping by acquiring multiple interleaved slices in each breathhold using slice‐selective T1ρ,adiab preparation pulses. The proposed‐sequence was implemented with two interleaved slices per breathhold scan and was quantitatively evaluated in phantom experiments and 10 healthy‐volunteers against a single‐slice T1ρ,adiab mapping sequence. The sequence was demonstrated in two patients with myocardial scar.ResultsThe phantom experiments showed the proposed‐sequence had slice‐to‐slice variation of 1.62% ± 1.05% and precision of 4.51 ± 0.68 ms. The healthy volunteer cohort subject‐wise mean relaxation time was lower for the proposed‐sequence than the single‐slice sequence (137.7 ± 5.3 ms vs. 148.4 ± 8.3 ms, p < 0.001), and spatial‐standard‐deviation was better (18.7 ± 1.8 ms vs. 21.8 ± 3.4 ms, p < 0.018). The mean within‐subject, coefficient of variation was 5.93% ± 1.57% for the proposed‐sequence and 6.31% ± 1.92% for the single‐slice sequence (p = 0.35) and the effect of slice variation (0.81 ± 4.87 ms) was not significantly different to zero (p = 0.61). In both patient examples increased T1ρ,adiab (maximum American Heart Association‐segment mean = 174 and 197 ms) was measured within the myocardial scar.ConclusionThe proposed sequence provides a twofold acceleration for myocardial T1ρ,adiab mapping using a multi‐slice approach. It has no significant difference in within‐subject variability, and significantly better precision, compared to a 2D T1ρ,adiab mapping sequence based on non‐selective adiabatic spin‐lock preparations.