| Objective To establish a clonorchis sinensis infection model in rabbits,and investigate the effects of different doses of infection on bile duct and hepatocyte injury in rabbits.To investigate the role of primovist in MRI diagnosing clonorchis sinensis by scanning experimental animals infected with different degrees of infection with plain and primovist enhanced MRI.Method The metacercarias of clonorchis sinensis were extracted by artificial digestion,collected and counted under microscope.400,600 and 800 metacercarias were given to 15 rabbits by oral in 3 groups named low-degree,medium-degree and high-degree infected group,normal saline was given to 5rabbits which were served as control group.All rabbits were sacrificed after 90 days and the liver specimens were performed with pathological examination.Siemens Verio 3.0 T MRI and special coil were used on scanning the control group and experimental group rabbit liver,T1 WI,T2WI,MRCP,DWI T1 apping and T1 WI images 20 minutes after Gd-EOB-DTPA enhanced image were scanned,Siemens Syngo workstation software were used for image post-processing and select ROI and calculated average values of T1 relaxation time of liver before and after enhancement.T1 WI,T2WI and enhanced images of clonorchis sinensis were observed,and the related to clonorchis sinensis infection after enhancement were analyzed by comparing the pathological sections.SPSS statistical analysis software were used to calculate the difference of results between images of different infected group at different time points before and after enhancement.Results(1)Rabbits in 3 infected groups were all infected successfully.Egg positive rates in feces reached 100% in 4 weeks post infection.The highest adult Clonorchis sinensis recovery rate in low,medium and high infected-groups were20.50%,15.17% and 23.38%.There was no statistical difference in the number of adults between the low and medium infection groups(P=0.24),the comparison of number of adults between low and medium infected-groups with high infected-group showed significant differences(P<0.01).The rabbit liver in the infected group was found that biliary ducts in the liver were thickened significantly,and a large number of live adult Clonorchis sinensis were found in the intrahepatic bile ducts and gallbladder;Observed with light microscope,the portal area was enlarged with collagen accumulation,the intrahepatic bile duct was thickened,the bile duct wall was thickened,the bile duct and surrounding tissues were inflamed,and low to high level intraepithelial neoplasia was observed in the endothelium of the bile duct.(2)MRI plain scan and MRCP images were observed,characteristic image features of clonorchis sinensis infection mainly included extensive expansion of intrahepatic bile ducts,subcapsular dilatation of the hepatic subcapsular and T1 hypointensity signal nearby the intrahepatic bile ducts.Combined with the enhanced scane image with primovist it can be found that the important diagnostic signs of the bile duct wall strengthened,the thickened of the bile duct wall,the biliary drainage is delayed during the hepatobiliary period,and the filling defect in the bile duct.And the degree of infection was corresponded to the results of pathological changes of the bile duct.(3)DWI scan showed that the average ADC of liver showed a downward trend with the progression of liver fibrosis stage at each time point.Analysis of correlation showed significant negative correlation between the number of infections and ADC values of liver.Rank-sum test indicated that the difference of ADC values between the liver fibrosis groups was statistically significant(P=0.042),and the difference of ADC values between the groups was statistically significant(H=2.83,P=0.005).One-way anova was used for comparison the time points T1 values and the number of adult pairwise contrast was LSD multiple tests results: the difference between T1 value of the liver before enhancement and the number of metacercaria of clonorchis sinensis was statistically significant(P=0.035).LSD multiple test results showed:before enhancement,10 minutes and 15 minutes after enhancement,three time points’ T1 values of liver between control group and the high infection group was statistically significant(P < 0.05),after 25 minutes difference of T1 values between control group and infection group and low infected group was statistically significant(P < 0.05),T1 values between the control group and 30 minutes after enhancement infection group was statistically significant(P < 0.05).Conclusion(1)Rabbit clonorchis sinensis infected model can effectively carry out the MRI imaging study of clonorchis sinensis.(2)The pathological results showed that clonorchis sinensis infection mainly caused damage to the intrahepatic bile duct system of rabbits,and then caused liver damage.(3)MRI plain scan combined with primovist enhancement has important diagnostic value for clonorchis sinensis infection. |
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