title: Comparison of centric and reverse-centric trajectories for highly accelerated three-dimensional saturation recovery cardiac perfusion imaging.
abstract: OBJECTIVE
  Highly undersampled three-dimensional (3D) saturation-recovery sequences are affected by k-space trajectory since the magnetization does not reach steady state during the acquisition and the slab excitation profile yields different flip angles in different slices. This study compares centric and reverse-centric 3D cardiac perfusion imaging.
  
  
  METHODS
  An undersampled (98 phase encodes) 3D ECG-gated saturation-recovery sequence that alternates centric and reverse-centric acquisitions each time frame was used to image phantoms and in vivo subjects. Flip angle variation across the slices was measured, and contrast with each trajectory was analyzed via Bloch simulation.
  
  
  RESULTS
  Significant variations in flip angle were observed across slices, leading to larger signal variation across slices for the centric acquisition. In simulation, severe transient artifacts were observed when using the centric trajectory with higher flip angles, placing practical limits on the maximum flip angle used. The reverse-centric trajectory provided less contrast, but was more robust to flip angle variations.
  
  
  CONCLUSIONS
  Both of the k-space trajectories can provide reasonable image quality. The centric trajectory can have higher CNR, but is more sensitive to flip angle variation. The reverse-centric trajectory is more robust to flip angle variation.
authors.affiliation: Department of Electrical & Computer Engineering, Brigham Young University, Provo, Utah, USA.
authors.forename: Haonan
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Electrical & Computer Engineering, Brigham Young University, Provo, Utah, USA.|Department of Radiology, University of Utah, Salt Lake City, Utah, USA.
authors.forename: Neal K
authors.initials: NK
authors.lastname: Bangerter
authors.affiliation: Department of Electrical & Computer Engineering, Brigham Young University, Provo, Utah, USA.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Park
authors.affiliation: Department of Radiology, University of Utah, Salt Lake City, Utah, USA.
authors.forename: Ganesh
authors.initials: G
authors.lastname: Adluru
authors.affiliation: Department of Radiology, University of Utah, Salt Lake City, Utah, USA.
authors.forename: Eugene G
authors.initials: EG
authors.lastname: Kholmovski
authors.affiliation: Siemens Healthcare USA Inc., New York, New York, USA.
authors.forename: Jian
authors.initials: J
authors.lastname: Xu
authors.affiliation: Department of Radiology, University of Utah, Salt Lake City, Utah, USA.
authors.forename: Edward
authors.initials: E
authors.lastname: DiBella
mesh_terms: D000368:Aged; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D059629:Signal-To-Noise Ratio
keywords: 3D cardiac perfusion; compressed sensing; k-space trajectory