ASA 126th Meeting Denver 1993 October 4-8

3aPA6. Quantitative ultrasonic imaging for tissue characterization.

James G. Miller Samuel A. Wickline Julio E. Perez Benico Barzilai Mark R. Holland Scott M. Handley Burton E. Sobel

Dept. of Phys. and Cardiovascular Div., Washington Univ., St. Louis, MO 63130

This presentation will illustrate relationships between physical acoustics and ultrasonic imaging for medical diagnosis. Ultrasonic tissue characterization is designed to complement two-dimensional echocardiography by providing information in addition to that derived from an assessment of tissue dimension and motion. The hypothesis is that indices based on (frequency-dependent) backscatter and attenuation can provide a noninvasive tool for the early diagnosis of diverse disease processes including ischemia and cardiomyopathy. Differentiation between mature infarct and acutely ischemic myocardium, which might benefit from reperfusion by angioplasty or thrombolysis, appears to be feasible on the basis of the frequency dependence of backscatter, which is lower in zones of infarct than in acutely ischemic or normal myocardium. Two-dimensional images are formed from scans made with the direction of propagation of ultrasound at varying angles relative to the local fiber orientation of the myocardium. Backscatter and attenuation vary substantially with the angle of insonification relative to myofibers. This research is designed to lay the groundwork for exploiting the anisotropy of myocardial ultrasonic properties to achieve improved understanding of cardiac mechanical properties (elasticity and compliance) in normal and diseased hearts. [Work supported by NIH HL40302, HL17646, HL42950.]