Accuracy evaluation in ultrasonic-based measurement of microscopic change in thickness

For the diagnosis of atherosclerosis, one acoustical method involves measuring the change in thickness of the arterial wall during one cardiac cycle and then noninvasively evaluating the elastic properties of the arterial wall. An alternative method for obtaining such a diagnosis is proposed, the phased tracking method, which can be used to accurately measure the instantaneous displacement signals on the intima and adventitia of the arterial wall from the skin surface using pulsive ultrasonic waves. A minute change in the thickness of the arterial wall of several micrometres is obtained by integrating the difference between two instantaneous displacement signals. Using a rubber plate in a water tank, the accuracy of the proposed method is evaluated by measuring such microscopic changes in thickness.