Setting-up Of Radiation-induced Kidney Injury In Rat Model And Evaluation Of Image Manifestations

[Abstract] Objective:To study the setting-up methods of radiation-induced kidney injury in rat model,to study pathological changes in the early phase of radiation-induced kidney injury,and to assess diagnostic value of CT and MRI in the early phase of radiation-induced kidney injury. To consecutively observe the performance of Color Doppler Flow Image(CDFI) in rats with early stage of unilateral radiation nephropathy,to study the renal hemodynamic changes and to assess the severity of radiation nephropathy.Methods:80Sprague Dawley rats were divided into four normal control groups and four experimental groups randomly, and the experimental groups received a single dose of20Gy to the left kidney. Images of CT and MRI were obtained and pathological observation on the kidneys at4,12,24,36weeks. Images of CDFI were obtained at4,12,24,36weeks after irradiation, respectively. The renal volume、the renal parenchyma thickness、the resistance index of renal artery and introrenal artery in all left kidneys were compared.Results:CT、MRI findings including kidney atrophy and the thin of kidney parenchyma and the loss of corticomedullary differentiation were observed at the scheduled study. CT show that the renal volume values of the experimental groups and the control group at24weeks,36weeks was significant difference (P<0.05),the value of the experimental groups were lower than the value of the normal control group.The renal parenchyma thickness values of the experimental groups and the control group at12、24、36weeks was significant difference (P<0.05),the value of the experimental groups were lower than the values of the normal control group. Radiation nephropathy were detected earlier with MRI than CT, and the sensitivity of MRI was higher than that of CT (P<0.05). MRI show that the renal volume values of the experimental groups and the control group at36weeks was significant difference (P<0.05),the value of the experimental groups were lower than the values of the normal control group.The renal parenchyma thickness values of the experimental groups and the control group at24-.36weeks was significant difference (P<0.05),the value of the experimental groups were lower than the values of the normal control group. CDFI show that the renal parenchyma echo of the experimental groups were strengthened as the disease progressed. The renal volume values and the renal parenchyma thickness values of the experimental groups and the control group at24weeks,36weeks was significant difference (P<0.05),the value of the experimental groups were lower than the values of the normal control group; the renal artery RI values of the two groups at36weeks were significant difference,(P <0.05) the RI values of the experimental groups were higher than the RI values of the normal control group, the introrenal artery RI values of the two groups at24、36weeks were significant difference(P<0.05), the RI values of the experimental groups were higher than the RI values of the normal control group. Pathological observation showed the morphological changes at4weeks after irradiation including glomerular and tubular injury. An improvement in glomerular and tubular lesions was observed by12、24、36weeks after irradiation.Conclusion:The radiation-induced kindey injury model can be setting up with the exposure of a single dose of20Gy radiation to the unilateral kidney of sprague dawley rats and morphological changes was observed. Early diagnosis of radiation-induced kidney injury can be performed with MRI and CT. CDFI might be a useful examination method in the diagnosis of early radiation nephropathy, and the hemodynamic changes may reflect the severity of radiation nephropathy.