An evaluation of hepatic ultrasound speed in injury models in rats: correlation with tissue constituents.

The speed of sound through the livers of 32 male Sprague-Dawley rats was measured. The study population consisted of four experimental groups: control, acute liver injury induced by carbon tetrachloride, fatty liver induced by a choline-deficient diet, and liver cirrhosis induced by administration of N-diethylnitrosamine. To examine possible correlations between the speed of sound and liver histology, biochemical measurements of the water, fat, and collagen content were made. The aim of the present study was to determine the effects of the characteristics of diseased liver tissue on the speed of sound, by studying the tissue constituents biochemically and by using a more accurate measurement of the speed of sound. The sound speed was 1591.6 +/- 6.7 m/s in the acute liver injury group, 1531.4 +/- 18.4 m/s in the fatty liver group, and 1624.9 +/- 6.7 m/s in the liver cirrhosis group. No significant correlation existed between the speed of sound and the water content in all groups taken together, whereas a good correlation was found in the fatty liver group (P < 0.0001, r = -0.858) and in cirrhosis (P < 0.0001, r = 0.760) when the groups were examined separately. These results indicate that the speed of sound is useful for diagnosing fatty liver for predicting the fat content.