Temporally resolved parametric assessment of Z‐magnetization recovery (TOPAZ): Dynamic myocardial T1 mapping using a cine steady‐state look‐locker approach. Issue 4 (30th August 2017)

• Record Type: Journal Article
• Authors: Weingärtner, Sebastian; Shenoy, Chetan; Rieger, Benedikt; Schad, Lothar R.; Schulz‐Menger, Jeanette; Akçakaya, Mehmet
• Is Part Of: Magnetic resonance in medicine. Volume 79:Issue 4(2018)
• Page Start: 2087
• Page End: 2100
• Publication Date: 2017-08-30
• Subjects: quantitative myocardial tissue characterization -- T1 mapping -- B1+ mapping -- cine -- cardiac imaging; Nuclear magnetic resonance -- Periodicals; Electron paramagnetic resonance -- Periodicals; 616.07548
• DOI: 10.1002/mrm.26887
• Languages: English
• ISSNs: 0740-3194

Abstract

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 B 1 + estimation is performed for reconstruction of cardiac phase‐resolved T1 and B 1 + 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 B 1 + 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 B 1 + assessment at a temporal resolution of 40 ms. Magn Reson Med 79:2087–2100, 2018. © 2017 International Society for Magnetic Resonance in Medicine.