An approach to modeling the relationship between ultrasonic propagation properties and constituent properties of mammalian tissues

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.]