The Study Of DEN-induced Rat HCC Model And Its Proton MR Spectroscopy

Purpose To introduce a simple method of establishing a reliable rat model of hepatocelullar carcinoma (HCC), and to analyze the MRI characteristics of different kinds of nodules in the development of HCC by a new MR scanner, and comparing with both the gross liver and pathologic slices.Methods Sixty male Wistar rats were divided into two groups: treated (50 rats) and control (10 rats). For the rats in the first group 0.01mg DEN were added into every 100 ml drinking water till week 15. Between week 1 to 20, the rats (2-3 DEN treated rats every week and 1 control every 2 weeks) were randomly chosen and scanned by MR before being killed in the following day. The data of MR performances of 83 nodules were analyzed.Results According to the dominant pathologic changes, the whole carcinogenic evolution could be divided into four stages: (1) toxic hepatitis (week 1-4), (2) mild to medium fibrosis (week 5-8), (3) formation of regenerative nodules (RNs) and liver cirrhosis (week 9-14), (4) HCC (week 15-20). Started from week 12 the dysplastic nodules (DNs) could be found in the treated rats. HCCs appeared since week 13 and in week 18-20 the diameter of HCC could be more than 20mm. More nodules couldbe identified based on T₂WI than on T₁WI and the HCCs commonly show hypointense on T₁WI.Conclusion Simply adding DEN in the drinking water is a reliable way to establish the rat HCC model with staging development and in sequential periods the formation of different nodules which could be possibly identified on MRI. This model is fit for the medical imaging study. There are relatively severe toxic reaction and mild flbrosis, comparing with the common pathologic characteristics of human beings. The decreasing of the nodule signal might inform its malignant property and routine plain MR scanning sequences have limited value on determining the nature of nodules.Part TwoIn vivo detection of metabolic changes by 'H-MRS in the Chemical Induced Rat Model of Hepatocellular CarcinomaPurpose: To investigate the serial changes of the hepatic metabolites in a chemical induced rat model of hepatocellular carcinoma (HCC) in vivo by a new clinical 1.5 T MR scanner, and make a brief discussion about our initial results and thefeasibility of this technique.Methods: 80 Male Wistar rats were included and divided into two groups: namely Diethyl nitrosamine (DEN) induced HCC model rats (n=60) and control rats (n=20). From week 7 to week 20 after DEN administration, every another week 10-12 animals (8-9 treated and 2-3 controls) were randomly scanned and sacrificed the following day. The serial hepatic changes were tested by both routine MRI and single voxel 'H-MRS using the fully relaxed water signal as an internal standard. According to the pathological results the whole process of carcinogenesis was divided into early and late periods (week 7¹3 and week 14-20 respectively). The concentrations of lipid and choline-containing metabolites of different groups and periods were calculated and analyzed.Results-. All of the listed tests were fully finished in 66 rats (48 treated and 18 controls). Of the MRS curves, 65.2 % (43/66) could be analyzed (mainly with resistant baseline with peaks appeared at right positions). From those qualified MRS curves there were up to seven peaks which could be identified: (1) glycogen and glucose, (2) choline-containing compounds, (3) olefin lipids, (4) glutamine and glutamate, (5) methylene lipid with a double carbon bond, (6) methylene lipids and (7) methyl lipids. The peaks of methylene and methyl lipids were usually combined together and became the most notable component. Comparing with that of the controls of the same stage, the integral of combined lipid peak of treated rats decreased (P=0.0145) and that of the choline-containing compounds increased (P=0.0119) in the late stage.Conclusions: 'H-MRS of rat liver in vivo by the new 1.5T MR scanner is practical. Our initial studies for the integrals of the lipid compounds and the choline-containing metabolites might be useful for a better understanding of thehepatic metabolic activity of this DEN induced rat HCC model.Part Three¹H-MRS of the liver in DEN induced hepatocellular carcinoma rats: an in vivo study with in vitro corroborationObjective To investigate the hepatic metabolic changes in the Diethylnitrosamine (DEN) induced rat hepatocellular carcinoma model by in vivo l H-MRS with in vitro corroboration.Methods DEN induced HCC models (n=60) and controls (n=20) of male Wistar rats were selected as candidates. From week 7 to week 20 since DEN administration, every another week 10-12 animals (8-9 treated and 2-3 controls) were randomly scanned and sacrificed the following day. The serial hepatic changes were tested by both routine MRI and single voxel 'H-MRS using the combined peak of methylene and methyl lipid as an internal standard. High resolution ' H-MRS was obtained from liver extracts of treated rats (n=19) and control rats (n=4), and the absolute metabolite concentrations were achieved relative to the internal standard ofd^TSV. The integrals of some metabolites were analyzed.Results According to the pathologic changes the whole process of carcinogenesiswas divided into early and late periods (week 7-13 and week 14-20 respectively). 12 treated rats and 2 controls died before being killed. All the listed tests were fully finished in 48 treated and 18 control rats. Of the MRS curves, 65.2% (43/66) were thought satisfied (with resistant baseline and peaks appeared at right positions). According to the results of in vivo 'H-MRS, the level of glycogen/glucose and total choline of the late treated rats increased comparing with both the controls in the same period and the early treated rats. The results of high resolution MRS showed that in the late treated rats, the concentration of total choline increased comparing with that of the early treated rats, and the concentration of glycogen/glucose increased comparing with that of the controls. And there were not significant difference between groups over other metabolites.Conclusions The concentration of some metabolites could be analyzed by either in vivo or in vitro ' H-MRS of rat liver, the results were corroborative from each other. Our initial results on the changing of the metabolic compounds in this animal model might be helpful for a better understanding of the metabolic changes in the hepatocarcinogenisis.Part Four The liver glycogen changes in DEN induced rat HCC model:...