The role of glycogen and phosphate in ultrasonic attenuation of liver.

The excess ultrasonic attenuation caused by adding glycogen and inorganic phosphate to liver homogenates has been studied to determine the underlying differences between attenuation coefficients of normal and diffusely diseased livers. Results show that glycogen has a higher than average specific absorption coefficient compared to other large molecular weight biomolecules. Since the glycogen content of liver can vary from 1%-10% of wet weight, this compound may have a major time-varying effect on the liver ultrasonic attenuation coefficient, even in normal subjects. In contrast, the excess attenuation of liver homogenate resulting from addition of inorganic phosphate was not significant at presumed physiological levels. The implications of these findings are discussed relative to tissue characterization efforts based on in vivo measurements of ultrasonic attenuation coefficients of liver.