title: Aortic pulse wave velocity measurements with undersampled 4D flow-sensitive MRI: comparison with 2D and algorithm determination.
abstract: OBJECTIVE
  To compare pulse wave velocity (PWV) measurements obtained from radially undersampled 4D phase-contrast magnetic resonance imaging (PC-MRI) with 2D PC measurements and to evaluate four PWV algorithms.
  
  
  METHODS
  PWV was computed from radially undersampled 3D, 3-directionally velocity-encoded PC-MRI (4D) acquisitions performed on a 3T MR scanner in 18 volunteers. High temporal resolution 2D PC scans serving as a reference standard were available in 14 volunteers. Four PWV algorithms were tested: time-to-upstroke (TTU), time-to-peak (TTP), time-to-foot (TTF), and cross-correlation (XCorr). Bland-Altman analysis was used to determine inter- and intraobserver reproducibility and to compare differences between algorithms. Differences in age and PWV measurements were analyzed with Student's t-tests. The variability of age-corrected data was assessed with a Brown-Forsythe analysis of variance (ANOVA) test.
  
  
  RESULTS
  2D (4.6-5.3 m/s) and 4D (3.8-4.8 m/s) PWV results were in agreement with previously reported values in healthy subjects. Of the four PWV algorithms, the TTU, TTF, and XCorr algorithms gave similar and reliable results. Average biases of +0.30 m/s and -0.01 m/s were determined for intra- and interobserver variability, respectively. The Brown-Forsythe test revealed that no differences in variability could be found between 2D and 4D PWV measurements.
  
  
  CONCLUSIONS
  4D PC-MRI with radial undersampling provides reliable and reproducible measurements of PWV. TTU, TTF, and XCorr were the preferred PWV algorithms.
authors.affiliation: Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53705-2275, USA. alwentland@wisc.edu
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Wentland
authors.forename: Oliver
authors.initials: O
authors.lastname: Wieben
authors.forename: Chris J
authors.initials: CJ
authors.lastname: François
authors.forename: Christina
authors.initials: C
authors.lastname: Boncyk
authors.forename: Alejandro
authors.initials: A
authors.lastname: Munoz Del Rio
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Johnson
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Grist
authors.forename: Alex
authors.initials: A
authors.lastname: Frydrychowicz
mesh_terms: D000465:Algorithms; D000704:Analysis of Variance; D001013:Aorta, Thoracic / Q000502:physiology*; D055424:Cardiac-Gated Imaging Techniques; D005528:Foot / Q000098:blood supply; 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*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015588:Observer Variation; D063177:Pulse Wave Analysis / Q000379:methods*; D012984:Software; D013223:Statistics as Topic