title: Analysis of pulse wave velocity in the thoracic aorta by flow-sensitive four-dimensional MRI: reproducibility and correlation with characteristics in patients with aortic atherosclerosis.
abstract: OBJECTIVE
  To measure aortic pulse wave velocity (PWV) using flow-sensitive four-dimensional (4D) MRI and to evaluate test-retest reliability, inter- and intra-observer variability in volunteers and correlation with characteristics in patients with aortic atherosclerosis.
  
  
  METHODS
  Flow-sensitive 4D MRI was performed in 12 volunteers (24 ± 3 years) and 86 acute stroke patients (68 ± 9 years) with aortic atherosclerosis. Retrospectively positioned 28 ± 4 analysis planes along the entire aorta (inter-slice-distance = 10 mm) and frame wise lumen segmentation yielded flow-time-curves for each plane. Global aortic PWV was calculated from time-shifts and distances between the upslope portions of all available flow-time curves.
  
  
  RESULTS
  Inter- and intra-observer variability of PWV measurements in volunteers (7% and 8%) was low while test-retest reliability (22%) was moderate. PWV in patients was significantly higher compared with volunteers (5.8 ± 2.9 versus 3.8 ± 0.8 m/s; P = 0.02). Among 17 patient characteristics considered, statistical analysis revealed significant (P < 0.05) but low correlation of PWV with age (r = 0.25), aortic valve insufficiency (r = 0.29), and pulse pressure (r = 0.28). Multivariate modeling indicated that aortic valve insufficiency and elevated pulse pressure were significantly associated with higher PWV (adjusted R(2) = 0.13).
  
  
  CONCLUSIONS
  Flow-sensitive 4D MRI allows for estimating aortic PWV with low observer dependence and moderate test-retest reliability. PWV in patients correlated with age, aortic valve insufficiency, and pulse pressure.
authors.affiliation: Department of Radiology, Medical Physics, University Medical Center Freiburg, Germany. mmarkl@northwestern.edu
authors.forename: Michael
authors.initials: M
authors.lastname: Markl
authors.forename: Wolf
authors.initials: W
authors.lastname: Wallis
authors.forename: Christoph
authors.initials: C
authors.lastname: Strecker
authors.forename: Beryl Primrose
authors.initials: BP
authors.lastname: Gladstone
authors.forename: Werner
authors.initials: W
authors.lastname: Vach
authors.forename: Andreas
authors.initials: A
authors.lastname: Harloff
mesh_terms: D000368:Aged; D000465:Algorithms; D001013:Aorta, Thoracic / Q000502:physiology / Q000503:physiopathology*; D001018:Aortic Diseases / Q000503:physiopathology*; D050197:Atherosclerosis / Q000503:physiopathology*; D001783:Blood Flow Velocity / Q000502:physiology; D005260:Female; D006439:Hemodynamics; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D011446:Prospective Studies; D012044:Regression Analysis; D015203:Reproducibility of Results; D055815:Young Adult