Dependence of Ultrasonic Nonlinear Parameter B/A on Fat

Abstract

This study deals with the relationship between the magnitude of acoustic nonlinearity, sound speed of tissues and the amount of fat present in them. A two-component model, i.e., nonfat and fat, has been assumed and equations that relate the nonlinear parameter (B/A) of a medium to the properties of its components have been derived for two cases. In the first case, the density and sound speed are the same for the two components; B/A is a linear function of fat concentration. To represent this case, mixtures of egg white and yolk were studied. Even though the differences in density and sound speed of the two egg components were within 1 percent of each other, B/A showed a deviation from linearity. In the second case, i.e., when the density and sound speed of the two components are not equal, a quadratic equation has been derived using mixture laws. Livers, fats, egg mixtures, and oil data were used to represent this case. B/A increased quadratically with fat concentration. The presence of proteins on the binary aqueous/fat mixtures modified the quadratic rule.

Evaluation of Sound Speed for Detection of Liver Fibrosis

“…23 In experimental settings, it is has been shown that the SV depends on the fat content of the tissue and is slower in fat compared to water and human tissue. [24][25][26] In this study, all patients with cirrhosis who were missed by the SV measurements were not only obese but also had a lower SV in the liver compared to the cutoff of value of 1589 m/s and the mean SV value for the population with cirrhosis.…”

Influences of structural factors of biological media on the acoustic nonlinearity parameter B/A

“…It is seen that the B/A value due to ribonuclease At decreases as it is denatured, which supports the result obtained by SDS denaturation. Errabolu et al (1987) have also observed the lower B/A value associated with denatured protein, in studies of the dependence of the B/A parameter on the different constituents of fatty tissues, by decomposing the fat tissues into three components, viz., water, oily residue: and solid residue. They pointed out that the solid residue, one of the dehydration products composed largely of denatured proteins, exhibits significantly lower B/A values.…”