Temporally resolved parametric assessment of Z-magnetization recovery (TOPAZ): Dynamic myocardial T1 mapping using a cine steady-state look-locker approach

Sebastian Weingärtner; Chetan Shenoy; Benedikt Rieger; Lothar R Schad; Jeanette Schulz-Menger; Mehmet Akçakaya

doi:10.1002/mrm.26887

Temporally resolved parametric assessment of Z-magnetization recovery (TOPAZ): Dynamic myocardial T₁ mapping using a cine steady-state look-locker approach

Magn Reson Med. 2018 Apr;79(4):2087-2100. doi: 10.1002/mrm.26887. Epub 2017 Aug 30.

Authors

Sebastian Weingärtner^{1

2

3}, Chetan Shenoy⁴, Benedikt Rieger³, Lothar R Schad³, Jeanette Schulz-Menger^{5

6}, Mehmet Akçakaya^{1

2}

Affiliations

¹ Electrical and Computer Engineering, University of Minnesota, Minneapolis, Minnesota, USA.
² Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, USA.
³ Computer Assisted Clinical Medicine, University Medical Center Mannheim, Heidelberg University, Mannheim, Germany.
⁴ Cardiovascular Division, Department of Medicine, University of Minnesota, Minneapolis, Minnesota, USA.
⁵ Working Group on Cardiovascular Magnetic Resonance Imaging, Experimental and Clinical Research Center, Joint Cooperation of the Max-Delbrück-Centrum and Charité-Medical University Berlin, Berlin, Germany.
⁶ Department of Cardiology and Nephrology, HELIOS Klinikum Berlin-Buch, Berlin, Germany.

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. Magn Reson Med 79:2087-2100, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Keywords: B1+ mapping; T1 mapping; cardiac imaging; cine; quantitative myocardial tissue characterization.

Publication types

Research Support, N.I.H., Extramural
Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Adult
Algorithms
Computer Simulation
Heart / diagnostic imaging*
Humans
Image Interpretation, Computer-Assisted
Image Processing, Computer-Assisted / methods*
Magnetic Resonance Imaging*
Male
Middle Aged
Models, Theoretical
Myocardium / pathology*
Phantoms, Imaging
Reproducibility of Results
Systole
Young Adult

Abstract

Publication types

MeSH terms

Grants and funding