title: Fast four-dimensional coronary MR angiography with k-t GRAPPA.
abstract: OBJECTIVE
  To investigate the effectiveness of k-t GRAPPA for accelerating four-dimensional (4D) coronary MRA in comparison with GRAPPA and the feasibility of combining variable density undersampling with conventional k-t GRAPPA (k-t(2) GRAPPA) to alleviate the overhead of acquiring autocalibration signals.
  
  
  METHODS
  The right coronary artery of nine healthy volunteers was scanned at 1.5 Tesla. The 4D k-space datasets were fully acquired and subsequently undersampled to simulate partially parallel acquisitions, namely, GRAPPA, k-t GRAPPA, and k-t(2) GRAPPA. Comparisons were made between the images reconstructed from full k-space datasets and those reconstructed from undersampled k-space datasets.
  
  
  RESULTS
  k-t GRAPPA significantly reduced artifacts compared with GRAPPA and high acceleration factors were achieved with only minimal sacrifices in vessel depiction. k-t(2) GRAPPA could further increase imaging speed without significant losses in image quality.
  
  
  CONCLUSIONS
  By exploiting high-degree spatiotemporal correlations during the rest period of a cardiac cycle, k-t GRAPPA and k-t(2) GRAPPA can greatly increase data acquisition efficiency and, therefore, are promising solutions for fast 4D coronary MRA.
authors.affiliation: Department of Biomedical Engineering, Northwestern University, Chicago, IL 60611, USA.
authors.forename: Peng
authors.initials: P
authors.lastname: Lai
authors.forename: Feng
authors.initials: F
authors.lastname: Huang
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Larson
authors.forename: Debiao
authors.initials: D
authors.lastname: Li
mesh_terms: D017023:Coronary Angiography / Q000379:methods; D003331:Coronary Vessels / Q000033:anatomy & histology*; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods*