Abstract
Literature values for ultrasonic attenuation, absorption, and velocity in several tissues, including brain, heart, kidney, liver, tendon, fat, and blood at frequencies of 1, 3 and 5 MHz, along with the percent constituency of each tissue (by weight) were used to develope an algorithm relating the acoustical propagation properties of a tissue to it's biological properties. Such an algorithm is hoped to provide the biological content of a tissue sample (e.g., % collagen content, % protein content, etc.…), given the ultrasonic propagation properties within that tissue. A first order model, assuming a linear relationship between constituency and acoustical properties, employs a least squares solution to a system of linear equations. This solution is a set of attenuation coefficients one, for each of the constituents considered. Results show that such a model works for only a limited number of highly structured tissues. A modified first order approach examines scattering (defined as attenuation minus absorption) as a function of collagen content alone. Here it is suggested that, as a function of frequency over the 0.5–7MHz range, the magnitude of scattering increases, but the dependency of scattering on collagen content is decreasing. [This work was supported in part by grants from NIH and FDA.]
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