Temporally resolved parametric assessment of Z-magnetization recovery (TOPAZ): dynamic myocardial T(1) mapping using a cine steady-state look-locker approach

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Item Type:	Article
Title:	Temporally resolved parametric assessment of Z-magnetization recovery (TOPAZ): dynamic myocardial T(1) mapping using a cine steady-state look-locker approach
Creators Name:	Weingaertner, S., Shenoy, C., Rieger, B., Schad, L.R., Schulz-Menger, J. and Akçakaya, M.
Abstract:	PURPOSE: To develop and evaluate a cardiac phase-resolved myocardial T1 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 T1 and B1+ estimation is performed for reconstruction of cardiac phase-resolved T1 and B1+ 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) T1 mapping sequence in terms of accuracy and precision. RESULTS: In phantom, TOPAZ T1 values with integrated B1+ correction are in good agreement with spin-echo T1 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 T1 times between the cardiac phases (analysis of variance: P = 0.14, coefficient of variation = 3.2 +/- 0.8%), but underestimation compared with SAPPHIRE (T1 time +/- precision: 1431 +/- 56 ms versus 1569 +/- 65 ms). In vivo precision is comparable to SAPPHIRE T1 mapping until middiastole (P > 0.07), but deteriorates in the later phases. CONCLUSIONS: The proposed sequence allows cardiac phase-resolved T1 mapping with integrated B1+ assessment at a temporal resolution of 40 ms.
Keywords:	Quantitative Myocardial Tissue Characterization, T1 Mapping, B1+ Mapping, Cine, Cardiac Imaging
Source:	Magnetic Resonance in Medicine
ISSN:	0740-3194
Publisher:	Wiley-Blackwell
Volume:	79
Number:	4
Page Range:	2087-2100
Date:	April 2018
Official Publication:	https://doi.org/10.1002/mrm.26887
External Fulltext:	View full text on PubMed Central
PubMed:	View item in PubMed

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