title: Repeatability and internal consistency of abdominal 2D and 4D phase contrast MR flow measurements.
abstract: OBJECTIVE
  The aim of this study was to assess the repeatability and internal consistency of flow measurements in the renal arteries and pararenal aorta with the use of standard two-dimensional (2D) and novel four-dimensional (4D) phase contrast (PC) magnetic resonance imaging (MRI).
  
  
  METHODS
  Ten healthy volunteers were imaged with a radially undersampled 4D PC technique centered over the renal arteries and with four 2D PC slices placed in the supra/infrarenal aorta and the left/right renal arteries; this MRI exam was performed twice on each subject. Flow measurements in all four vessels were computed from 2D and 4D PC data sets. Student's t-tests (P < .05) were used to assess differences between in-flow (suprarenal aorta) and out-flow (infrarenal aorta + left renal artery + right renal artery) for the 2D and 4D techniques, to compare in- and out-flow, and to compare repeated measurements of 2D and 4D flow measurements.
  
  
  RESULTS
  No significant differences were found in repeated measurements of 2D (P = .15) or 4D (P = .39) data. No significant difference was found between 2D (3.4 ± 2.8 mL/cardiac cycle) and 4D (3.5 ± 2.7 mL/cardiac cycle) in- and out-flow differences (P = .88). Out-flow was greater than in-flow for 2D measurements (P = .003); no difference was found for 4D measurements.
  
  
  CONCLUSIONS
  The 2D and 4D techniques demonstrated strong repeatability and internal consistency of flow measurements in the renal arteries and pararenal aorta.
authors.affiliation: Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, 1111 Highland Avenue, Madison, WI, USA 53705-2275, USA. alwentland@wisc.edu
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Wentland
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Grist
authors.forename: Oliver
authors.initials: O
authors.lastname: Wieben
mesh_terms: D000328:Adult; D000465:Algorithms; D001011:Aorta / Q000033:anatomy & histology / Q000502:physiology*; D001783:Blood Flow Velocity / Q000502:physiology; D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D012077:Renal Artery / Q000033:anatomy & histology / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult