Evaluating the regional elastic modulus of a cylindrical shell with nonuniform wall thickness.

Abstract

For noninvasive diagnosis of atherosclerosis, we attempted to evaluate the elasticity of the arterial wall by measuring small changes in thickness caused by the heartbeat. The elasticity of the arterial wall has been evaluated noninvasively by measuring the change in diameter of the artery or the pulse-wave velocity; however, there is no method for noninvasively evaluating the elasticity of the arterial wall from changes in its thickness. Employing the phased tracking method that we developed, changes in thickness of less than 100 µm were measured in each regional area, which corresponded to the diameter of the ultrasonic beam. The elasticity of the arterial wall could be evaluated with better spatial resolution from the change in thickness than from the change in diameter of the artery or pulse-wave velocity. We therefore propose a method for evaluating the elastic modulus of an arterial wall of nonuniform wall thickness. In basic experiments employing silicone rubber tubes with nonuniform wall thickness as arterial models, the elastic moduli of silicone rubber tubes were evaluated by measuring changes in wall thickness. These results confirm the value of the proposed method.