title: Quantitative assessment of aortic elasticity with aging using velocity-vector imaging and its histologic correlation.
abstract: OBJECTIVE
  Velocity-vector imaging (VVI) represents a valuable new method for noninvasive quantification of vascular properties associated with aging. The purpose of this study was to assess the correlations between VVI parameters and histological changes with aging.
  
  
  RESULTS
  Fourteen mongrel dogs were classified as either young (n=7; age, 1-2 years; female; weighing 22-29 kg) or senescent (n=7; age, 8-12 years; female; weighing 36-45 kg). The short-axis image of the descending thoracic aorta was obtained for VVI analysis with transesophageal echocardiography. The location of the image was identified using fluoroscopic guidance, and the aortic tissue was extracted. After dividing the aortic wall into 6 segments, both regional and segmental tissue collagen and elastin contents were quantified and correlated with the aortic elastic properties. In the regional analysis, the M-mode-derived aortic dimensions and elastic moduli except for intima-media thickness were not significantly different between the groups, whereas the VVI-derived aortic area and fractional area changes showed more dilated and stiffer aorta in senescent dogs. Also, fractional area change was significantly correlated with the tissue collagen content unlike the M-mode-derived elastic moduli. In the segmental analysis, the radial velocity, circumferential strain, and strain rates of VVI were more reduced in senescent dogs than young dogs, and the radial velocity and circumferential strain showed independent associations with the collagen content of the corresponding aortic wall.
  
  
  CONCLUSIONS
  VVI was a feasible method for direct quantification of aortic elastic properties with a significant histological correlation.
authors.affiliation: Division of Cardiology, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Sung-Ai
authors.initials: SA
authors.lastname: Kim
authors.forename: Kyung Hye
authors.initials: KH
authors.lastname: Lee
authors.forename: Ho-Yeon
authors.initials: HY
authors.lastname: Won
authors.forename: Sungha
authors.initials: S
authors.lastname: Park
authors.forename: Ji Hyung
authors.initials: JH
authors.lastname: Chung
authors.forename: Yangsoo
authors.initials: Y
authors.lastname: Jang
authors.forename: Jong-Won
authors.initials: JW
authors.lastname: Ha
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D001011:Aorta / Q000000981:diagnostic imaging* / Q000473:pathology*; D001707:Biopsy, Needle; D004285:Dogs; D004548:Elasticity / Q000502:physiology*; D005069:Evaluation Studies as Topic; D005260:Female; D007150:Immunohistochemistry; D023421:Models, Animal; D063177:Pulse Wave Analysis / Q000379:methods*; D015203:Reproducibility of Results; D014463:Ultrasonography; D059289:Vascular Stiffness
keywords: aging; aorta; collagen; elasticity; velocity-vector imaging