Evaluation of the influence of severe steatosis on fibrosis measurement in a rat model with NAFLD by DMA and ARFI technology

Hepatic steatosis is an important histologic factor in non-alcoholic fatty liver disease (NAFLD) spectrum. The aim of this study is to evaluate the impact of steatosis on liver fibrosis stiffness measurement by acoustic radiation force impulse (ARFI) elastography. Meanwhile, the dynamical mechanical analysis (DMA) test is performed to quantify the mechanical behavior of rat livers. The rat models were conducted in 110 rats. The right lobes of the liver were used for ARFI and DMA measurement, respectively. In rats with NAFLD, the mean elasticity values were significantly higher in rats with severe steatosis by histology compared to those mild or without steatosis for F0-F2 fibrosis stages (DMA, P = 0.001; ARFI, P = 0.012); There were observed no difference in rats with severe steatosis compared to those mild or without steatosis when discriminating rat according to the presence or absence of severe (F3-F4) fibrosis. Therefore, the presence of severe steatosis is a significant factor for assessing the lower stage of fibrosis.