Value of acoustic radiation force impulse elastography in evaluation of nonalcoholic fatty liver disease and hepatic fibrosis in rats / 中国医学影像技术

ABSTRACT

Objective To evaluate the value of acoustic radiation force impulse (ARFI) elastography in assessment of nonalcoholic fatty liver disease (NAFLD) and hepatic fibrosis in rats.Methods Models with various degrees of NAFLD severity were conducted in 110 rats by feeding high fat emulsion.The right liver lobe of rat models were processed and embedded in a fabricated gelatin solution to measure the shear wave velocity (SWV) by ARFI.And the other liver lobes were used for histologic assessment.Based on NAFLD activity score (NAS),the final pathologic NAFLD diagnosis were considered as normal group (NAS=0),simple steatosis (SS) group (1≤NAS≤2),borderline (3≤NAS≤4) group and nonalcoholic steatohepatitis (NASH) group (NAS≥5).The diagnostic accuracy of the SWV parameters in evaluating NAFLD severity and fibrosis stages was studied using ROC curves.Results The difference of SWV values among normal group,SS group,borderline group and NASH group was statistically significant (F=31.53,P＜0.001).Taking SWV≥ 2.54 m/s as the diagnostic standard to differentiate normal rats from rats with SS,and SWV≥2.90 m/s to differentiate SS from NASH in rats,the area under ROC curve (AUC) was 0.922 (95％CI [0.871,0.973],P＜0.001) and 0.882 (95％ CI [0.807,0.956],P＜0.001) respectively.The sensitivity and specificity were 93.5 ％ and 100 ％ for differentiating normal and SS groups,83.3 ％ and 84.2 ％ for differentiating SS and NASH groups.Taking SWV≥3.48 m/s as cutoff to predict fibrosis (≥F2 stage),the AUC was 0.963 (95％CI [0.909,1.000],P＜0.001),the sensitivity was 92.9％ and the specificity was 97.6％.Taking SWV≥3.61 m/s as cutoff to predict severe fibrosis (≥F3 stage),the AUC was 0.997 (95％CI [0.990,1.000],P＜0.001),sensitivity was 100％ and specificity was 98.9％.The same high validity was maintained as in the prediction of cirrhosis (F4 stage) with the cutoff as SWV≥4.50 m/s,and the AUC was 0.993 (95％CI [0.982,1.000],P＜0.001),the sensitivity was 100 ％ and the specificity was 96.8％.Conclusion ARFI elastography is a promising method for differentiating the different severity of NAFLD and staging the degree of hepatic fibrosis with NAFLD in rat models.