Acoustic Radiation Force Impulse And Hepatic Artery Resistive Index On Evaluating Rabbit Liver Fibrosis Model

Objective: Based on developing the liver fibrosis model,the purpose of this study is to investigate the diagnostic value of acoustic radiation force impulse(ARFI)and hepatic artery resistive index(HARI)in different stages of liver fibrosis and to analyze the mechanism and relevance.Methods: 36 healthy female New Zealand white rabbits were randomly divided into 4groups(Group A,B,C and D),within which Group A was the control group comprising 6rabbits while Group B,C and D each with 10 rabbits served as the liver fibrosis groups.All groups were fed with ordinary feed whereas Group A was regularly subcutaneously injected with equivalent volumes of physiological saline compared to the carbon tetrachloride-olive oil mixture injected in liver fibrosis groups.The experiment period lasted 4 weeks,8 weeks,12 weeks for Group B,C,and D respectively,and at the end of each experiment period(4th week,8th week and 12 th week),two rabbits from the control group were randomly selected to make comparison with the experimental groups.Before the start and after the end of the experimental period,the rabbits in each group were drawn to check the Aspartate Transaminase(AST),Alanine Transaminase(ALT),Albumin(ALB)and Albumin-to-globulin ratio(AGR).Conventional 2D ultrasound,Doppler ultrasound and ARFI examination of the liver were also performed to obtain HARI and SWV.After the experiment,rabbit livers were taken out for histopathological examination.The histopathological and ultrastructural changes of the normal control group and every stage of liver fibrosis were observed and compared.Results: According to the statistical analysis on the pathological stage of rabbit livers,there was no statistical difference before and after the experiment for AST,ALT,ALB and AGR in stage F0(P>0.05).AST and ALT in stage F1-F4 were higher than F0 and statistical differences existed among F1,F2,F3 and F4(P<0.05).ALB and AGR in stage F1-F4 were lower than F0 with statistical differences among F1,F2,F3 and F4(P<0.05).Pathologically,hepatic lobules were well organized in stage F0,and hepatic cells were radially distributed to surroundings with central veins in the center.Hepatic sinusoids ran normally and cholangioles were clearly visualized.There were some inflammatory cell infiltration and cell swelling in stage F1 in addition to the results of F0.In stage F2,some inflammatory cell infiltration,small vessel stasis and some fibrosis in portal area were performed.In stage F3,there were remarkable inflammatory cell infiltration,hepatic cell swelling,cholestasis,small vessel stasis,augmented fibrosis and some regeneration nodules.Stage F4 comprised a great number of inflammatory cell infiltration,the hepatic cells arranged in disorder,lots of fibrosis appeared and connected to each other,lots of regeneration nodules and pseudolobulus formation.2-D ultrasound showed no abnormal findings in F0.Hepatic parenchyma had a mild dense echogenicity in stage F1,while hepatic volume increased and parenchyma had a dense and heightened echogenicity in stage F2.The hepatic capsule showed mild uneven contour line,parenchyma has a coarse and heterogeneous echogenicity,wall echoes of biliary ducts and portal veins showed enhanced demonstration in stage F3.Stage F4 showed that an uneven contour line was performed in Hepatic capsule,parenchyma had a coarse and disorganized echogenicity.Doppler ultrasound displayed that no statistical difference was performed between stage F0 and F1 for HARI(P>0.05),whereas HARI for stage F2,F3,F4 showed statistical difference compared to stage F0 and F1(P<0.05)which were gradually increased with fibrosis advanced.ARFI showed a statistical difference between stage F0 and F1(P<0.05),and SWV values became higher with serious fibrosis.Pearson correlation analysis revealed a positive correlation between HARI and SWV.Conclusion: The SWV measured by ARFI showed an increasing trend with the progress of liver fibrosis,suggesting that ARFI has a higher value in diagnosing liver fibrosis stage.HARI has certain value in diagnosing liver fibrosis from stage F2 to F4.The SWV measured by ARFI is positively correlated with HARI.