Regional vascular mechanical properties by three-dimensional
intravascular ultrasound with finite element analysis.
Vonesh, Michael J., Cheol-Hyung Cho, Jack V. Pinto, Bonnie J. Kane,
David S. Lee, Sanford I. Roth, Krishnan B. Chandran, David D.
McPherson.
Department of Medicine, Section of Cardiology, Northwestern
University Medical School, Chicago, Illinois, College of Engineering,
Department of Biomedical Engineering, University of Iowa, Iowa City,
Iowa
APStracts 3:0290H, 1996.
A method employing intravascular ultrasound (IVUS) and simultaneous
hemodynamic measurements, with resultant finite element analysis
(FEA) of accurate three-dimensional IVUS reconstructions (3DR), was
developed to estimate the regional distribution of arterial
elasticity. Methods: Human peripheral arterial specimens (iliac and
femoral, n=7) were collected post-mortem, and perfused at three
static transmural pressures: 80, 120, and 160 mm Hg. At each
pressure, IVUS data were collected at 2.0 mm increments through a
20.0 mm segment and used to create an accurate 3DR. Mechanical
properties were determined over normotensive and hypertensive ranges.
An FEA and optimization procedure was implemented in which the
elemental elastic modulus was scaled to minimize the displacement
error between the computer-predicted and actual deformations. The
"optimized" elastic modulus (Eopt) represents an estimate of
the component element material stiffness. A dimensionless variable
([beta]), quantifying structural stiffness, was computed. Results:
Eopt of non-diseased tissue regions (n=80) was greater than
atherosclerotic regions (n=88) for both NORM and HYP pressurization:
NORM: 9.3 +/- 0.98 vs. 3.5 +/- 0.30, and HYP: 11.3 +/- 0.72 vs. 8.5
+/- 0.47, respectively (Mean +/- SEM x 106 dynes/cm2; p<0.01vs
non-diseased). No differences in structural stiffness ([beta])
between non-diseased and atherosclerotic tissue were noted at NORM
pressurization. With HYP pressurization, [beta] of atherosclerotic
regions were greater than non-diseased regions: 21.5 +/- 2.21 vs.
14.0 +/- 2.11, respectively (p < 0.03). This method provides a
means to identify regional in-vivo variations in mechanical
properties of arterial tissue.
Received 8 August 1995; accepted in final form 27 June 1996.
APS Manuscript Number H745-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 25 July 1996