title: Assessment of proximal pulmonary arterial stiffness using magnetic resonance imaging: effects of technique, age and exercise.
abstract: BACKGROUND
  To compare the reproducibility of pulmonary pulse wave velocity (PWV) techniques, and the effects of age and exercise on these.
  
  
  METHODS
  10 young healthy volunteers (YHV) and 20 older healthy volunteers (OHV) with no cardiac or lung condition were recruited. High temporal resolution phase contrast sequences were performed through the main pulmonary arteries (MPAs), right pulmonary arteries (RPAs) and left pulmonary arteries (LPAs), while high spatial resolution sequences were obtained through the MPA. YHV underwent 2 MRIs 6 months apart with the sequences repeated during exercise. OHV underwent an MRI scan with on-table repetition. PWV was calculated using the transit time (TT) and flow area techniques (QA). 3 methods for calculating QA PWV were compared.
  
  
  RESULTS
  PWV did not differ between the two age groups (YHV 2.4±0.3/ms, OHV 2.9±0.2/ms, p=0.1). Using a high temporal resolution sequence through the RPA using the QA accounting for wave reflections yielded consistently better within-scan, interscan, intraobserver and interobserver reproducibility. Exercise did not result in a change in either TT PWV (mean (95% CI) of the differences: -0.42 (-1.2 to 0.4), p=0.24) or QA PWV (mean (95% CI) of the differences: 0.10 (-0.5 to 0.9), p=0.49) despite a significant rise in heart rate (65±2 to 87±3, p<0.0001), blood pressure (113/68 to 130/84, p<0.0001) and cardiac output (5.4±0.4 to 6.7±0.6 L/min, p=0.004).
  
  
  CONCLUSIONS
  QA PWV performed through the RPA using a high temporal resolution sequence accounting for wave reflections yields the most reproducible measurements of pulmonary PWV.
authors.affiliation: Division of Cardiovascular and Diabetes Medicine , Medical Research Institute, University of Dundee , Dundee , UK.
authors.forename: Jonathan R
authors.identifier: 0000-0001-5842-842X
authors.initials: JR
authors.lastname: Weir-McCall
authors.affiliation: Department of Clinical Radiology , Ninewells Hospital and Medical School , Dundee , UK.
authors.forename: Anu
authors.initials: A
authors.lastname: Kamalasanan
authors.affiliation: Division of Cardiovascular and Diabetes Medicine , Medical Research Institute, University of Dundee , Dundee , UK.
authors.forename: Deidre B
authors.initials: DB
authors.lastname: Cassidy
authors.affiliation: Division of Cardiovascular and Diabetes Medicine , Medical Research Institute, University of Dundee , Dundee , UK.
authors.forename: Allan D
authors.initials: AD
authors.lastname: Struthers
authors.affiliation: Scottish Centre for Respiratory Research, Medical Research Institute, University of Dundee , Dundee , UK.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Lipworth
authors.affiliation: Division of Cardiovascular and Diabetes Medicine , Medical Research Institute, University of Dundee , Dundee , UK.
authors.forename: J Graeme
authors.initials: JG
authors.lastname: Houston
keywords: Imaging/CT MRI etc