Evaluation of regional elastic modulus of cylindrical shell with nonuniform wall thickness

We have been attempting to evaluate the elasticity of the arterial wall by measuring the small changes in its thickness caused by heartbeat in order to provide a method for diagnosing atherosclerosis noninvasively. Although the elasticity of the arterial wall has been evaluated noninvasively by measuring change in artery diameter and pulse-wave velocity, no method for noninvasively evaluating the elasticity of the arterial wall from change in its thickness has yet been reported. Using the phased tracking method proposed by our group, we measured small changes in thickness, changes of less than 100 μm, in each regional area, which corresponds to the diameter of the ultrasound beam. From change in thickness, the elasticity of the arterial wall can be evaluated with better spatial resolution than that obtained with measurement of change in arterial diameter and pulse wave velocity. Here we propose a method for evaluating the elastic modulus of the arterial wall with nonuniform wall thickness by measuring changes in its thickness. In basic experiments employing silicone rubber tubes with nonuniform wall thickness as a model of the artery, the elastic modulus of each silicone rubber tube is evaluated from the determined change in wall thickness. These experimental results confirm the promise of the method proposed here.