| Objective:To explore the feasibility and influencing factors of shear wave elastography(SWE)technique in assessing the severity of nonalcoholicai fatty liver disease(NAFLD)and hepatic fibrosis.Methods:SD rats(88)were randomly divided into control group(40)and experimental group(48).Control group were fed with a standard diet while experimental group models were fed with different diets in order to create various degrees of NAFLD severity.The rats were imaged using SWE in the time of 1st,2nd,3rd,8th,12 th week,respectively.On completion of the ultrasonography,the rabbits were sacrificed for removal of the liver.The liver tissue sections were observed with light microscope.The other part of liver tissues were preserved for use in the mRNA expression studies.The groups were determined according to the final pathologic diagnosis.Finally,Statistical analysis was performed.Results:1.General conditions of models were as followed: the rats all survived and the final pathologic diagnose included normal in 42 rats,simple steatosis in 5 rats,borderline in 5 rats,NASH in 30 rats and cirrhosis in 6 rats.According to liver fibrosis,there was stage 0 in 52 rats,stage 1 in 6 rats,stage 2 in 6 rats,stage 3 in 18 rats,and stage 4 in 6 rats.2.There were significant positive correlations between Emean and NAFLD severity in all rat(r=0.838,P<0.001).3.Emean differed significantly among pathological groups(F=113.58,P<0.001).Emean in NASH and cirrhosis groups was significantly higher than that in normal,simple steatosis and borderline groups(P<0.001).Emean of the cirrhosis group was also significantly higher than that of the NASH group(P<0.001).No significant differences in Emean were noted among the normal group,simple steatosis group and borderline group(P>0.05).4.There were significant positive correlations between Emean and hepatic fibrosis stages(r=0.82,P<0.001)in all animals.Emean differed significantly according to fibrosis stage(F=25.5,P<0.05).A significant difference in Emean were noted between every two fibrotic groups(P<0.05 for all),with the exception of the difference between F1 and F2 groups(P>0.05).5.All histopathologic findings,including fibrosis(r=0.815,P<0.001),steatosis(r=0.804,P<0.001),inflammation(r=0.789,P<0.001)and hepatocyte ballooning(r=0.772,P<0.001),had significant positive correlations with liver elasticity.However,fibrosis had significant independent correlations with liver elasticity(B=1.241,P<0.001),rather than steatosis.6.The optimal SWE cutoff value was 6.0 k Pa for NASH.The area under the ROC curve were 0.95,with a sensitivity of 88.9% and a specificity of 86.5%.For classifying fibrosis stage,corresponding optimal SWE cutoff values were 6.3,7.4,8.6 and 9.7 k Pa,and the area under the ROC curve were 0.87,0.89,0.93,0.98,with a sensitivity of 83.3%,93.3%,100%,100% and a specifificity of 85.5%,83.1%,91.3%,92.7%.7.The mRNA expression of MCP-1(r=0.678,P<0.001),TNF-α(r=0.340,P=0.001),collagen type Ⅰ(r=0.402,P<0.001),and α-SMA(r=0.561,P<0.001)had positive correlations with Emean.Among them,the MCP-1(B=0.560,P<0.001)and collagen type Ⅰ(B=0.429,P<0.001)were independent risk factors for NAFLD.Conclusions:1.SWE could be used to assess the severity of NAFLD.2.SWE could be a noninvasive method to differentiate NASH from SS with high accuracy.3.SWE could be useful for the evaluation of hepatic fibrosis in NAFLD.4.Emean is correlated with fibrosis but not with steatosis.5.MCP-1 and collagen type Ⅰ could be the major biomolecular indicators which influencing liver stiffness. |
