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Purpose To develop and evaluate a cardiac phase‐resolved myocardial T 1 mapping sequence. Methods The proposed method for temporally resolved parametric assessment of Z‐magnetization recovery (TOPAZ) is based on contiguous fast low‐angle shot imaging readout after magnetization inversion from the pulsed steady state. Thereby, segmented k‐space data are acquired over multiple heartbeats, before reaching steady state. This results in sampling of the inversion‐recovery curve for each heart phase at multiple points separated by an R‐R interval. Joint T 1 and estimation is performed for reconstruction of cardiac phase‐resolved T 1 and maps. Sequence parameters are optimized using numerical simulations. Phantom and in vivo imaging are performed to compare the proposed sequence to a spin‐echo reference and saturation pulse prepared heart rate–independent inversion‐recovery (SAPPHIRE) T 1 mapping sequence in terms of accuracy and precision. Results In phantom, TOPAZ T 1 values with integrated correction are in good agreement with spin‐echo T 1 values (normalized root mean square error = 4.2%) and consistent across the cardiac cycle (coefficient of variation = 1.4 ± 0.78%) and different heart rates (coefficient of variation = 1.2 ± 1.9%). In vivo imaging shows no significant difference in TOPAZ T 1 times between the cardiac phases (analysis of variance: P = 0.14, coefficient of variation = 3.2 ± 0.8%), but underestimation compared with SAPPHIRE (T 1 time ± precision: 1431 ± 56 ms versus 1569 ± 65 ms). In vivo precision is comparable to SAPPHIRE T 1 mapping until middiastole ( P > 0.07), but deteriorates in the later phases. Conclusions The proposed sequence allows cardiac phase‐resolved T 1 mapping with integrated assessment at a temporal resolution of 40 ms. Magn Reson Med 79:2087–2100, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
Weingärtner et al. (Wed,) studied this question.