title: Compensation of signal loss due to cardiac motion in point-resolved spectroscopy of the heart.
abstract: OBJECTIVE
  To study the influence of cardiac motion on point-resolved single voxel spectroscopy (PRESS) of the human heart and to propose an improved sequence design to compensate for cardiac motion-related signal losses.
  
  
  METHODS
  Numerical simulations and in vivo measurements were performed to study motion effects in cardiac spectroscopy. Based on the findings, an improved PRESS sequence with reduced free induction decay spoiling areas was implemented. Myocardial triglyceride (TG) content as estimated with the improved PRESS sequence was compared with the default PRESS sequence commonly used for spectroscopy in nonmoving tissues that was provided by the manufacturer.
  
  
  RESULTS
  Numerical simulations and in vivo data show the importance of optimal trigger delays to avoid signal losses in cardiac spectroscopy. The improved PRESS sequence was found to yield a significantly reduced sensitivity to cardiac motion and trigger delay setting and provided a 1.7-fold increase in signal-to-noise ratio on average compared with the default PRESS sequence. Intrasubject variation of myocardial TG content was reduced with the improved sequence compared with the default PRESS sequence (coefficient of variation: 0.11 ± 0.03 versus 0.23 ± 0.06).
  
  
  CONCLUSIONS
  Improvement of the sequence design is essential to reduce the sensitivity of PRESS to cardiac motion.
authors.affiliation: Institute for Biomedical Engineering, University and ETH Zurich, Switzerland; Cardiology Division, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Kilian
authors.initials: K
authors.lastname: Weiss
authors.forename: Severin
authors.initials: S
authors.lastname: Summermatter
authors.forename: Christian T
authors.initials: CT
authors.lastname: Stoeck
authors.forename: Sebastian
authors.initials: S
authors.lastname: Kozerke
mesh_terms: D000328:Adult; D003198:Computer Simulation; D005260:Female; D064368:Healthy Volunteers; D006321:Heart / Q000502:physiology*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D009068:Movement; D059629:Signal-To-Noise Ratio; D014280:Triglycerides / Q000378:metabolism
chemical_list: D014280:Triglycerides
keywords: cardiac motion; cardiac spectroscopy; creatine; motion compensation; signal-to-noise ratio; triglyceride