- Poster presentation
- Open Access
- Published:
Fat-water separated myocardial T1 mapping with IDEAL-T1 saturation recovery gradient echo imaging
Journal of Cardiovascular Magnetic Resonance volume 16, Article number: P65 (2014)
Background
Myocardial T1 mapping is emerging as powerful tool for tissue characterization, however the presence of intramyocardial or epicardial fat can contaminate T1 values through partial voluming, or preclude analysis, particularly in areas of infarct or thin walled myocardium, such as the right ventricle. We propose and evaluate a new combined fat-water separated saturation-recovery imaging sequence (IDEAL-T1) for water-separated T1 mapping.
Methods
The IDEAL-T1 approach combines a gated, segmented multi-echo gradient recalled echo readout for fat-water separation, based on the "iterative decomposition of water and fat with echo asymmetry and least squares estimation" (IDEAL) method[1], with saturation recovery T1 mapping[2–4]. Images at 4 saturation recovery (TS) times were acquired at a basal slice in diastole over 2 breathholds; one for a non-saturation prepared image, with >4 seconds of recovery between segments, and another for 3 images with incremental TS times. Typical parameters: (Siemens Sonata, 1.5T) TE 2.06, 4.43, 6.8 ms, TR 8.59, flip angle 20°, TS 302-701 ms, FOV 360 × 259 mm, acquisition matrix 256 × 129, phase resolution 70%, 6/8 partial Fourier, 27 views per segments (4 shots per image). Data from water-separated images was scaled by the non-saturated image and fit to a 1-parameter mono-exponential curve, using a Bloch equations simulation look-up table approach to correct for readout-effects on apparent saturation efficiency. In phantom experiments, with a physiologic range of T1 and T2 values (14 phantoms), IDEAL-T1 was validated against an inversion spin-echo sequence. In-vivo evaluation of myocardial T1 was completed in 6 healthy individuals and compared to a single-shot saturation recovery sequence (SASHA)[2] in the left ventricle.
Results
Simulations reveal negligible dependence on T1, T2, and off-resonance (up to 250 Hz), but dependence on B1 errors and saturation efficiency. Phantom experiments show excellent correlation with spin-echo values (R2 0.9996, p < 0.0001) with a mean underestimation of 2.4 ms (Figure 1) and a standard deviation of the difference of 7.4 ms. In vivo evaluation shows a larger underestimation, with a mean difference of -32.5 ms (Figure 1) and a standard deviation of the difference of 12.3 ms. Sample fat and water separated images are shown in Figure 2, where a thin rim of RV fat is revealed on the fat image, and a fat and water profile through the wall illustrates the large region of fat and water overlap.
Conclusions
IDEAL-T1 provides the benefit of fat-water separation with quantitative myocardial T1-mapping with a small underestimation in T1. Areas of thin myocardium, including the right ventricle, may benefit from resolving zones of partial voluming with fat by having water only images for analysis.
Funding
The authors acknowledge financial support from CIHR, AIHS, WCHRI.
References
Reeder: JMRI. 2007
Chow: MRM. 2013
Higgins: Med Phys. 2005
Wacker: MRM. 1999
Author information
Authors and Affiliations
Rights and permissions
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
About this article
Cite this article
Pagano, J.J., Chow, K., Yang, R. et al. Fat-water separated myocardial T1 mapping with IDEAL-T1 saturation recovery gradient echo imaging. J Cardiovasc Magn Reson 16 (Suppl 1), P65 (2014). https://doi.org/10.1186/1532-429X-16-S1-P65
Published:
DOI: https://doi.org/10.1186/1532-429X-16-S1-P65
Keywords
- Phantom Experiment
- Saturation Recovery
- Siemens Sonata
- Saturation Efficiency
- Saturation Recovery Sequence