The objective of the research is the identification and characterization of abnormalities of myocardial structure in humans based upon the analysis of reflected ultrasound. This objective will be approached by developing and testing methods of ultrasonic tissue characterization based on the quantitative evaluation of regional echo amplitude data from two-dimensional echocardiograms, using clinically applicable instrumentation and ahalytic approaches. The studies will be performed using tissue equivalent phantoms; in excised canine and human hearts; in open-chest canines and in closed-chest canines and humans. The investigational approach will be directed at three major areas. 1. Some of the anatomic and physiologic factors responsible for ultrasonic backscatter from mammalian myocardium will be studied. Specifically, the investigations will include the study of regional variability of integrated backscatter, specifically differences between the right and left ventricles; the relationship between the total content and spatial distribution of collagen and the pattern and amount of returning ultrasound; the relationship between regional blood flow and integrated backscatter in intact hearts; and the relationship between the phase of cardiac contraction and the level of integrated backscatter. 2. Several technical factors will be studed which potentially affect echo amplitude data obtained from standard 20 echocardiographic instruments. The investigations will include the study of regional variability of quantitative echo image texture as a function of range and azimuth within the field-of-view; the effect of the coordinate system in which data are analyzed (polar vs. rectangular) on artifactual regional texture variability; and the effect of the method of gain compensation echo image texture. 3. Based upon the results of the studies outlined above, a set of quantitative measures of regional echo amplitude will be developed and tested in acute myocardial infarction in dogs and humans; and in cardiomyopathies in humans, including amyloidosis, hemochromatosis, and hypertrophic cardiomyopathy. The final goal of the research proposed is a noninvasive method of myocardial structure analysis based upon the amount and pattern of reflected ultrasound.
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