Construction of Reference Data for Tissue Characterization of Arterial Wall Based on Elasticity Images

Abstract

Previously, we developed the phased tracking method [H. Kanai et al.: IEEE Trans. Ultrason. Ferroelectr. Freq. Control 43 (1996) 791] for measuring the minute change in thickness during one heartbeat and the elasticity of the arterial wall. By comparing pathological images with elasticity images measured with ultrasound, elasticity distributions for respective tissues in the arterial wall were determined. We have already measured the elasticity distributions for lipids and fibrous tissues (mixtures of smooth-muscle and collagen fiber) [H. Kanai et al.: Circulation 107 (2003) 3018]. In this study, elasticity distributions were measured for blood clots and calcified tissues. We discuss whether these elasticity distributions, which were measuerd in vitro, can be used as reference data for classifying cross-sectional elasticity images measured in vivo into respective tissues. In addition to the measurement of elasticity distributions, correlations between collagen content and elasticity were investigated with respect to fibrous tissue to estimate the collagen and smooth-muscle content based on elasticity. Collagen and smooth-muscle content may be important factors in determining the stability of the fibrous cap of atherosclerotic plaque. Therefore, correlations between elasticity and elements of the tissue in the arterial wall may provide useful information for the noninvasive diagnosis of plaque vulnerability.

Evaluation of Plaque Stabilization by Fluvastatin with Carotid Intima- Medial Elasticity Measured by a Transcutaneous Ultrasonic-Based Tissue Characterization System

“…4). In in vitro experiments, as reported previously, the main components of tissue have their own elasticities 16) . By referring to the elasticity library, we can speculate as to the tissue type whose elastic modulus is close to that of each pixel.…”

“…Plaques consist of various tissue components, and we previously reported the comparison of the elastic modulus with histologically corresponding tissues, such as lipids, blood clots and calcification 16) . In that report, the distributions of lipids and blood clots were relatively narrow and pure; however, those of collagen, smooth muscle and calcification were wide and rather scattered.…”

“…Values for baPWV were measured from the ascending point shown by the right brachial pulse volume recorder to the ascending point indicated by each ankle pulse volume recorder. The distance between the right brachium and ankle was estimated as described previously 16) .…”

“…Conventional evaluations are based on the tion of lipids, blood clots, fibrous tissue and calcified tissue in vitro have been reported previously, and an elasticity image can be classified into tissue components using the reference data obtained by in vitro experiments 16) . The usefulness of measuring the elastic modulus of the common carotid arteries (CCAs) by ultrasound imaging to detect early-stage atherosclerotic lesions caused by risk factors with regard to lifestyle-related disease has also been reported 15) .…”

Measurement of nonlinear property of artery wall using remote cyclic actuation

“…26 However, it is difficult to discriminate some tissues, such as lipids and blood clots, because of the small differences in their elasticity. 27 Therefore, we are attempting to measure other mechanical properties.…”