title: Second-order motion compensated PRESS for cardiac spectroscopy.
abstract: 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.
  
  
  
  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.
  
  
  
  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).
  
  
  
  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.
authors.affiliation: Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Fuetterer
authors.affiliation: Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland.|Division of Imaging Sciences and Biomedical Engineering, King's College London, London, UK.
authors.forename: Christian T
authors.initials: CT
authors.lastname: Stoeck
authors.affiliation: Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland.|Division of Imaging Sciences and Biomedical Engineering, King's College London, London, UK.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Kozerke
mesh_terms: D000328:Adult; D057791:Cardiac Imaging Techniques / Q000379:methods*; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009068:Movement / Q000502:physiology; D059629:Signal-To-Noise Ratio; D055815:Young Adult
keywords: PRESS; cardiac motion; cardiac spectroscopy; gradient moment nulling; motion compensation; triglyceride