QUANTITATIVE MODELING OF THE ANISOTROPY OF ULTRASONIC BACKSCATTER FROM CANINE MYOCARDIUM

We report extensions and new results of the First Time Domain Born app roximation model used by Mottley and Miller to describe the anisotropy of ultrasonic backscatter measured in canine myocardium. The interact ion of an ultrasonic plane wave impulse with a single cylindrical scat terer using time and frequency domain approaches is reviewed. Myocardi al tissue is modeled as a suspension of aligned cylindrically shaped s catterers uniformly distributed in a homogeneous medium. We propose ex tensions to this model to deal with nonideal scatterer orientation, by introducing axial distribution functions and scatterer size distribut ions based on histology, modeled as a uniform distribution. The backsc atter coefficient in the range 2.0-8.0 MHz is calculated. An algorithm to compute the average differential scattering cross section is prese nted. Ultrasonic elastic properties of myocardial tissue are discussed . Results of the anisotropy of the numerically computed backscatter pa rameters for model media having nominal mechanical and acoustic proper ties of canine myocardial tissue are presented and compared to availab le experimental data along with discussion of possible conclusions.