- Poster presentation
- Open Access
Fat-water separated myocardial T1 mapping with IDEAL-T1 saturation recovery gradient echo imaging
© Pagano et al.; licensee BioMed Central Ltd. 2014
- Published: 16 January 2014
- Phantom Experiment
- Saturation Recovery
- Siemens Sonata
- Saturation Efficiency
- Saturation Recovery Sequence
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.
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, 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) in the left ventricle.
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.
The authors acknowledge financial support from CIHR, AIHS, WCHRI.
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