title: Clinical evaluation of CAIPIRINHA: comparison against a GRAPPA standard.
abstract: OBJECTIVE
  To evaluate image quality when using a CAIPIRINHA sampling pattern in comparison to a standard GRAPPA sampling pattern in patients undergoing a routine three-dimensional (3D) breathheld liver exam. CAIPIRINHA uses an optimized phase encoding sampling strategy to alter aliasing artifacts in 3D acquisitions to improve parallel imaging reconstruction.
  
  
  METHODS
  Twenty patient volunteers were scanned using a 3D VIBE acquisition with an acceleration factor of four using a CAIPIRINHA and standard GRAPPA sampling pattern. CAIPIRINHA and GRAPPA images were evaluated by three radiologists in a two alternative forced choice test, and the Wilcoxon signed rank test was performed.
  
  
  RESULTS
  The CAIPIRINHA sampling pattern was preferred in an average of 68% of the comparisons, and the Wilcoxon signed rank test showed a significant improvement in CAIPIRINHA images (P = 0.014). This analysis indicates that in the given sample set, CAIPIRINHA preference over the GRAPPA standard was statistically significant.
  
  
  CONCLUSIONS
  This work shows that for an acceleration factor of four, a CAIPIRINHA accelerated VIBE acquisition provides significantly improved image quality in comparison to the current GRAPPA standard. This allows a further reduction in imaging time for similar spatial resolutions, which can reduce long breathhold requirements in abdominal imaging, and may be particularly helpful in patients who cannot provide requisite breathholds with current protocols.
authors.affiliation: Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, USA; Case Center for Imaging Research, Case Western Reserve University and University Hospitals Case Medical Center, Cleveland, Ohio, USA.
authors.forename: Katherine L
authors.initials: KL
authors.lastname: Wright
authors.forename: Michael W
authors.initials: MW
authors.lastname: Harrell
authors.forename: John A
authors.initials: JA
authors.lastname: Jesberger
authors.forename: Luis
authors.initials: L
authors.lastname: Landeras
authors.forename: Dean A
authors.initials: DA
authors.lastname: Nakamoto
authors.forename: Smitha
authors.initials: S
authors.lastname: Thomas
authors.forename: Dominik
authors.initials: D
authors.lastname: Nickel
authors.forename: Randall
authors.initials: R
authors.lastname: Kroeker
authors.forename: Mark A
authors.initials: MA
authors.lastname: Griswold
authors.forename: Vikas
authors.initials: V
authors.lastname: Gulani
mesh_terms: D000005:Abdomen / Q000473:pathology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D016477:Artifacts; D062485:Breath Holding; D003287:Contrast Media / Q000737:chemistry; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods* / Q000592:standards; D008099:Liver / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000592:standards; D008875:Middle Aged; D015588:Observer Variation; D012984:Software; D013997:Time Factors; D055815:Young Adult
chemical_list: D003287:Contrast Media
keywords: CAIPIRINHA; GRAPPA; body imaging; parallel imaging; sampling strategy