[Tissue characterization of the liver using ultrasound attenuation in an animal experiment]

Frequency-dependent attenuation of sound is considered a characteristic parameter of the interaction between sound and tissue and has been studied particularly in the liver via many different techniques. Due to the relatively wide scatter of the measured single values, especially in pathological liver samples, a clinically feasible application of the procedure has not yet been found. In the present paper, the suitability of the frequency-dependent coefficient of sound attenuation for tissue characterization with comparable experimental conditions in vitro was tested in a statistically representative collection of histologically defined tissue specimens of rat liver. Several statistical procedures were used (cluster analysis, discrimination analysis). Normal livers can be usually distinguished from pathological specimens by means of the frequency-dependent coefficient of sound attenuation with only slight scatter of the individual values. Although the latter differ on the average from normal specimens, they diverge considerably in respect of single values resulting in significant differences only in case of extensive tissue damage (cirrhosis). On the basis of tissue classifications in clinical and pathological use, only a rough tissue differentiation is possible. By using additional parameters of the interaction between sound and tissue, sonographic differentiation of pathologically changed tissue my be improved.