Evaluation of Hepatic Steatosis Using Acoustic Structure Quantification Ultrasound in a Rat Model: Comparison with Pathology and MR Spectroscopy

Abstract

Purpose: To assess the diagnostic performance of the focal disturbance (FD) ratio calculated by acoustic structure quantification (ASQ) technique in assessing the hepatic steatosis and to determine the significant affecting factors for FD ratio in a dietary-induced fatty liver disease rat animal model using histopathology as a reference of standard. Methods: Thirty-two F344 male rats were fed a methionine/choline-deficient diet with a variable duration (i.e., 0 weeks for the control, a half-week, or 1, 2, 3, 4, 5, or 6 weeks

n=4). At the end of each diet period, ASQ ultrasound and MR spectroscopy (MRS) were performed. Then, the rat was sacrificed and histopathologic examination of the liver was performed for the reference of standard. To assess the diagnostic performance of the FD ratio in evaluating the degree of hepatic steatosis, receiver operating characteristic curve analysis was performed. The Spearman correlation coefficient was calculated to assess the correlation between the ordinal values, and multivariate linear regression analysis was used to identify significant determinant factors for the FD ratio. Results: The FD ratio showed excellent diagnostic performance in assessing the degree of hepatic steatosis (area under the curve: 1.000 for 5-33% steatosis, 0.981 for >33-66% steatosis and 0.965 for >66% steatosis) and was comparable to MRS. There was a strong negative linear correlation between the FD ratio and the estimated fat fraction on MRS (Spearman rho, -0.903

P<0.001). The multivariate linear regression analysis showed that the degree of hepatic steatosis (P<0.001) and fibrosis stage (P=0.022) were significant factors affecting the FD ratio. Conclusions: The FD ratio could provide good diagnostic performance in assessing the degree of hepatic steatosis, with a strong negative linear correlation with the estimated fat fraction on MRS. The degree of steatosis and stage of fibrosis on histopathology were significant affecting factors for FD ratio.