title: AORTIC PULSE WAVE VELOCITY MEASURED BY PULSE WAVE IMAGING (PWI): A COMPARISON WITH APPLANATION TONOMETRY.
abstract: BACKGROUND
  Arterial stiffness is a well-established indicator of cardiovascular disease outcome. Pulse Wave Velocity (PWV) is a surrogate for arterial stiffness that is measured either globally using carotid to femoral applanation tonometry or locally using biomedical imaging methods. Pulse Wave Imaging (PWI) is an ultrasound-based method for both qualitative visualisation of pulse wave propagation and quantitative estimation of arterial stiffness. The objective of this study is to assess the PWI performance in PWV estimation by comparing local abdominal aortic PWV values obtained by PWI to the carotid-femoral PWV measured by applanation tonometry.
  
  
  METHODS
  A total of 18 subjects (age 18-66, 32.5±14.5) with no history of cardiovascular disease were consecutively tested by both PWI and tonometry.
  
  
  RESULTS
  The correlation coefficientrbetween values found by the two methods was found to be equal to 0.68. A linear regression yielded PWVPWI= 1.02* PWVtonometry+0.15. Tukey mean-difference plots indicated that PWVPWIwas significantly lower than PWVtonometry(-0.3 m/s) at lower PWV values (PWV≤7 m/s), whereas PWVPWIwas significantly higher (+1.4 m/s) than PWVtonometryat higher PWV values (PWV>7 m/s).
  
  
  CONCLUSIONS
  Despite the regional nature of the PWVPWImeasurements, as opposed to the global PWVtonometrymeasurements, abdominal PWVPWIand carotid-femoral PWVtonometryvalues were found to be similar, with an average bias equal to 0.25 m/s. Such a bias and its variation with PWV may be partially explained by both physiological variations of PWV along the arterial tree and by the increasing uncertainty of the PWV estimate by PWI as PWV increases.
authors.affiliation: Ultrasound and Elasticity Imaging Laboratory, Department of Biomedical Engineering, Columbia University, New York, NY, USA.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Vappou
authors.affiliation: Ultrasound and Elasticity Imaging Laboratory, Department of Biomedical Engineering, Columbia University, New York, NY, USA.
authors.forename: Jianwen
authors.initials: J
authors.lastname: Luo
authors.affiliation: Department of Cardiology, Columbia University, New York, NY, USA.
authors.forename: Kazue
authors.initials: K
authors.lastname: Okajima
authors.affiliation: Department of Cardiology, Columbia University, New York, NY, USA.
authors.forename: Marco
authors.initials: M
authors.lastname: Di Tullio
authors.affiliation: Ultrasound and Elasticity Imaging Laboratory, Department of Biomedical Engineering, Columbia University, New York, NY, USA.
authors.forename: Elisa
authors.initials: E
authors.lastname: Konofagou
keywords: Applanation Tonometry; Arterial stiffness; Pulse Wave Velocity; Ultrasound Imaging