Second-order motion compensated PRESS for cardiac spectroscopy

Abstract

Purpose Second‐order motion compensation for point‐resolved spectroscopy (PRESS) is proposed to allow for robust single‐voxel cardiac spectroscopy throughout the entire cardiac cycle and at various heart rates.
 Methods Bipolar FID spoiling gradient pairs compensating for first and second‐order motion were designed and implemented into a cardiac‐triggered PRESS sequence on a clinical MR system. A numerical three‐dimensional model of cardiac motion was used to optimize and validate the gradient waveforms. In vivo measurements in healthy volunteers were obtained to assess the signal‐to‐noise ratio (SNR) and triglyceride‐to‐water ratio (TG/W). SNR gains and variability of TG/W of the proposed approach were evaluated against a conventional PRESS sequence with optimized gradients.
 Results The proposed sequence increases the mean SNR by 32% (W) and 23% (TG) on average with significantly lower variability for different trigger delays. The variability of TG/W quantification over the cardiac cycle is significantly decreased with second‐order motion compensated PRESS when compared with conventional PRESS with reduced‐spoiler gradients (coefficient of variation: 0.1 ± 0.02 versus 0.37 ± 0.26).
 Conclusion Second‐order motion compensated PRESS effectively reduces cardiac motion–induced signal degradation during FID spoiling, providing higher SNR and less variability for TG/W quantification. The sequence is considered promising to assess the TG/W modulation during various interventions including pharmacologically induced stress. Magn Reson Med 77:57–64, 2017. © 2016 Wiley Periodicals, Inc.