Black-blood native T1 mapping: Blood signal suppression for reduced partial voluming in the myocardium

Abstract

Purpose: To study the feasibility of black-blood contrast in native T₁ mapping for reduction of partial voluming at the blood-myocardium interface.

Methods: A saturation pulse prepared heart-rate-independent inversion recovery (SAPPHIRE) T₁ mapping sequence was combined with motion-sensitized driven-equilibrium (MSDE) blood suppression for black-blood T₁ mapping at 3 Tesla. Phantom scans were performed to assess the T₁ time accuracy. In vivo black-blood and conventional SAPPHIRE T₁ mapping was performed in eight healthy subjects and analyzed for T₁ times, precision, and inter- and intraobserver variability. Furthermore, manually drawn regions of interest (ROIs) in all T₁ maps were dilated and eroded to analyze the dependence of septal T₁ times on the ROI thickness.

Results: Phantom results and in vivo myocardial T₁ times show comparable accuracy with black-blood compared to conventional SAPPHIRE (in vivo: black-blood: 1562 ± 56 ms vs. conventional: 1583 ± 58 ms, P = 0.20); Using black-blood SAPPHIRE precision was significantly lower (standard deviation: 133.9 ± 24.6 ms vs. 63.1 ± 6.4 ms, P < .0001), and blood T₁ time measurement was not possible. Significantly increased interobserver interclass correlation coefficient (ICC) (0.996 vs. 0.967, P = 0.011) and similar intraobserver ICC (0.979 vs. 0.939, P = 0.11) was obtained with the black-blood sequence. Conventional SAPPHIRE showed strong dependence on the ROI thickness (R² = 0.99). No such trend was observed using the black-blood approach (R² = 0.29).

Conclusion: Black-blood SAPPHIRE successfully eliminates partial voluming at the blood pool in native myocardial T₁ mapping while providing accurate T₁ times, albeit at a reduced precision. Magn Reson Med 78:484-493, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Keywords: MSDE; SAPPHIRE; T1 Mapping; black-blood; partial voluming.