Free-breathing simultaneous myocardial T1 and T2 mapping with whole left ventricle coverage

PURPOSE
To develop a free-breathing sequence, that is, Multislice Joint T₁-T₂, for simultaneous
measurement of myocardial T₁ and T₂ for multiple slices to achieve whole left-ventricular coverage.

METHODS
Multislice Joint T₁-T₂ adopts slice-interleaved acquisition to collect 10 single-shot electrocardiogram-triggered images for each slice prepared by saturation and T₂ preparation to simultaneously estimate myocardial T₁ and T₂ and achieve whole left-ventricular coverage. Prospective slice-tracking using a respiratory navigator and retrospective image registration are used to reduce through-plane and in-plane motion, respectively. Multislice Joint T₁-T₂ was validated through numerical simulations and phantom and in vivo experiments, and compared with saturation-recovery single-shot acquisition and T₂-prepared balanced Steady-State Free Precession (T₂-prep SSFP) sequences.

RESULTS

Phantom T₁ and T₂ from Multislice Joint T₁-T₂ had good accuracy and precision, and were insensitive to heart rate. Multislice Joint T₁-T₂ yielded T₁ and T₂ maps of nine left-ventricular slices in 1.4 minutes. The mean left-ventricular T₁ difference between saturation-recovery single-shot acquisition and Multislice Joint T₁-T₂ across healthy subjects and patients was 191 ms (1564 ± 60 ms versus 1373 ± 50 ms; P < .05) and 111 ms (1535 ± 49 ms vs 1423 ± 49 ms; P < .05), respectively. The mean difference in left-ventricular T₂ between T₂-prep SSFP and Multislice Joint T₁-T₂ across healthy subjects and patients was −6.3 ms (42.4 ± 1.4 ms vs 48.7 ± 2.5; P < .05) and −5.7 ms (41.6 ± 2.5 ms vs 47.3 ± 2.7; P < .05), respectively.

CONCLUSION
Multislice Joint T₁-T₂ enables quantification of whole left-ventricular T₁ and T₂ during free breathing within a clinically feasible scan time of less than 2 minutes.