Quantitative Study Of Funtional MRI In Experimental Animal Models With Liver Fibrosis And Clinical Application

Part 1 The construction of experimental animal models with liver fibrosisPurpose To construct a stable, reliable, and consistently animal models with liver fibrosis; to study liver lesions on MRI and CT, and to prepare for the further quantitative analysis and assessment for the functional MRI study.Methods Fifty male Sprague-Dawley rats and thirty male New Zealand rabbits were used in this study,which were randomly assigned to the experimental group (rabbits n=20;rats n=40) and the control group (rabbits n=10;rats n=10). To duplicate model of liver fibrosis, the rats were intraperitoneal injected with CCL4,and the rabbits were transcutaneously infected with schistosomiasis cercariae. The rats were performed with MRI and MDCT after 20 weeks time, and the rabbits were performed with MRI and MDCT in the 8th,10th and 12th week. The observation on liver lesion was conducted by HE staining, Masson trichrome staining, transmission electron microscopy, and meanwhile the degree of fibrosis and inflammation was pathologically graded.Results Only inflammatory infiltration were observed in the 4th week in the rabbits infected with schistosomiasis cercariae.The acute foreign granuloma node formed by worm eggs were observed in the 6th week,and then collagen deposition were observed in the 8th week. After that, the degree of collagen deposition was increased on the 10th and 12th week.All the experimental models were successfully duplicated with liver fibrosis,the score of liver fibrosis were similar in two kinds of models,but the score of inflammation between two kinds of models showed statistically significant difference,and the rats gain higher score than the rabbit did.MDCT and MR imaging showed indirect signs,such as liver size shrunk,and ascites. The liver volume were calculated with post-processed method on MDCT,and the volume of model groups were statistically significantly lower than that in the control groups.And the multiple observation on MRI showed that the branch of portal venous were extended,and the degree were aggravated over times.Conclusion These two kinds of experimental animal models with liver fibrosis can help to understand the complex condition of human natural evolution. MDCT and MRI imaging can show the indirect sign of liver size reduction and ascites.Part 2 Quantitative study of DTI in experimental animal models with liver fibrosisPurpose Two kinds of experimental animal models were performed with DTI,and the results were correlated with the pathology results,to explore the feasibility and value of DTI in quantitative study of liver fibrosis.Methods Two kinds of experimental animal models of liver fibrosis (10 rats were intraperitoneal injected with CCL4 and 18 New Zealand rabbits were transcutaneously infected with schistosomiasis cercariae) and the control ones (5 rats and 10 rabbits) were used in this study. The rats were performed with DTI imaging 20 weeks later and in vitro,and the rabbits were performed with DTI imaging in the 8th,10th and 12th week (EPI, TR/TE=1600/68.1, b=500s/mm2).The observation on liver lesion was conducted by HE staining, Masson trichrome staining, transmission electron microscopy, and meanwhile the degree of fibrosis and inflammation was pathologically graded. The apparent diffusion coefficient (ADC) and the fractional anisotropy(FA)of liver were measured on rats(in vivo and in vitro) and rabbits (8th week,10th week,12th week),the results were correlated with the pathology results. Statistical analysis was using SPSS13.0, take significant level of 0.05.Results Pathology results confirmed two kinds of experimental animal models were successfully estabished. There was no statistically significant difference between the two model groups for the degree of liver fibrosis.And degree of the inflammation in the rat model group was statistically significant difference were higher than that in the rabbit model group.Meanwhile, steatosis of liver was widely distributed in the rat model group.The change of ADC values and FA value in the two model groups was similar, compared with the controls, the ADC values was decrease and FA value was increase.The ADC values of rats (in vivo)and ADC values of rabbits were both had statistically significant different from the control groups.The ADC values of rabbit model group were decrease as time pass by,and the ADC values between different pathological grading were statistically significant difference.There was significantly negative correlation between ADC values and pathological grading of fibrosis(in vivo ADC of rats r=-0.607 P=0.016; rabbits r=-0.765 P=<0.01).Conclusion There was significantly negative correlation between ADC values and pathological grading of fibrosis in the two kinds of experimental animal models with liver fibrosis.ADC values can be quantitative evaluated with liver fibrosis.Part 3 Quantitative study of'H-MRS in experimental animal models with liver fibrosisPurpose Two kinds of experimental animal models were performed with 1H-MRS,and the results were correlated with the pathology results.To explore the feasibility and value of 'H-MRS in quantitative study of liver fibrosis.Methods Two kinds of experimental animal models of liver fibrosis (10 rats were intraperitoneal injected with CCL4 and 18 New Zealand rabbits were transcutaneously infected with schistosomiasis cercariae) and the control ones(5 rats and 10 rabbits) were used in this study. The rats were performed with 1H-MRS imaging after 20 weeks,and the rabbits were performed with 1H-MRS in the 8th,10th and 12th week (PRESS, TR/TE= 1500/35, NEX8, none water suppress).The observation on liver lesion was conducted by HE staining, Masson trichrome staining, transmission electron microscopy, and meanwhile the degree of fibrosis and inflammation was pathologically graded. The 1H-MRS analysis was performed on workstation, and the results were correalted with the pathology results. Statistical analysis were using SPSS 13.0, take significant level of 0.05Results Pathology results confirmed two kinds of experimental animal models were successfully estabished. There was no statistically significant difference between the two model groups for the degree of liver fibrosis.And degree of the inflammation in the rat model group was statistically significant difference were higher than that in the rabbit model group.Meanwhile, steatosis of liver was widely distributed in the rat model group. A significant statistical difference was observed between the control group vs.the liver fibrosis groups in choline (Cho). There is significantly positive correlation between Cho and pathological grading of fibrosis(rats r=0.642, P<0.01; rabbits r=0.643, P<0.01)Conclusion There was significantly positive correlation between Cho and pathological grading of fibrosis in the two kinds of experimental animal models with liver fibrosis.Cho can be quantitative evaluated with liver fibrosis.Part 4 Quantitative study of T2*map in experimental animal models with liver fibrosis Purpose Two kinds of experimental animal models were performed with T2*Map, and the results were correlated with the pathology results.To explore the feasibility and value of T2*Map in quantitative study of liver fibrosis.Methods Two kinds of experimental animal models of liver fibrosis (10 rats were intraperitoneal injected with CCL4 and 18 New Zealand rabbits were transcutaneously infected with schistosomiasis cercariae) and the control ones (5 rats and 10 rabbits) were used in this study. The rats were performed with T2*Map after 20 weeks,and the rabbits were performed with T2*Map in the 8th,10th and 12th week (GRE, TR=100, FA=40, NEX 6). The observation on liver lesion was conducted by HE staining, Masson trichrome staining, transmission electron microscopy, and meanwhile the degree of fibrosis and inflammation was pathologically graded.The R2* value were measured on workstation, and the results were correalted with the pathology results. Statistical analysis were using SPSS13.0, taken significant level of 0.05Results Pathology results confirmed two kinds of experimental animal models were successfully estabished. There was no statistically significant difference between the two model groups for the degree of liver fibrosis.And degree of the inflammation in the rat model group was statistically significant difference were higher than that in the rabbit model group.Meanwhile, steatosis of liver was widely distributed in the rat model group. There is significantly positive correlation between R2* values and liver iron content (r=0.966, P<0.01).And the liver iron content in liver fibrosis rats was higher than that in liver fibrosis rabbits. The R2* values of liver fibrosis rabbit were increase as time pass by. There was significantly positive correlation between R2* values of liver fibrosis rabbits and pathological grading of fibrosis(r=0.807, P<0.01)Conclusion There was significantly positive correlation between R2* values and pathological grading of fibrosis. R2* values can be quantitative evaluated with liver fibrosis.Part 5 Quantitative study of T2*map in Clinical application:Preliminary studiesPurpose To explore the feasibility and value of T2*Map in quantitative study of liver iron content in a clinic study.Methods Twenty-six patients with focal liver lesion were performed with T2*Map (FGRE, TR=100, FA=40, NEX 2). The R2* value of liver lesion and liver tissue around the lesion were measured on workstation, and the results were correalted with the pathology results. Statistical analysis was using SPSS13.0, take significant level of 0.05.Results All the patients were verified by postoperative pathological examination,there were 23 cases of primary liver carcinoma(11 were poorly-differentiated,8 were intermediately-differentiated and 4 were well-differentiated),1 case of hemangioma and 2 cases of focal nodular hyperplasia (FNH).There is significantly positive correlation between R2* values and liver iron content (r=0.567,P=0.003). R2* values of liver in patiens with malignant tumor were higher than the one with benign tumor, whereas no significant statistical difference was observed. A significant statistical difference was observed between liver tissue vs. liver tumor in R2* values.There is no significant statistical difference among different pathological grading of liver tumor.Conclusion R2* values can be quantitative evaluated with liver iron content.The R2* values were lower in liver tumor than the normal liver,which can be used as a feature to identify liver lesion.