The Repair Process And The Expressions Of VEGF After Radiofrequency Ablation In Normal Rabbit Liver Tissue

Objective:We observation the expressions of VEGF and characteristic of tissue repair in normal rabbit liver at different times after radiofrequency ablation.Method:RFA lesions were created in the livers of 24 rabbits , which were divided into six groups randomly. Animals underwent hepatic RFA were killed after performing MR imaging instantly and at 3 days,1 week,2 weeks,4 weeks,8 weeks after RAF procedure respectively. The correlation between MRI and pathologic findings was investigated and Immunohisto- chemistry was used to detect the expressions of VEGF.Results:Pathology of hepatic tissue after radiofrequency ablation: Shortly after RFA, the RFA lesion become cellular edema, intercellular substance region hyperemia, hemorrhage; At 3 days, the coagulation nec- rosis were seen in the RFA lesions and at the areas between ablation areas and normal tissue showed marked infiltration by neutrophils , lymphocytes; at 1 week, small vessels, a small quantity fibroblasts and inflammation cells were seen at the areas between ablation areas and normal tissue; at 2 weeks, the necrosis areas is same as that at 1 week, around the necrosis areas large quantity fibrous connective tissue and inflammation cells were seen along with hepatocyte nodular hyperplasia;at 4 weeks, a peripheral fibrovascular restoration rim were more obvious;at 8 weeks, most of hepatocyte regen- erate,completely repair almost.The expressions of VEGF in Immunohistochemistry staining: positive expressions of VEGF is detected by immunohistochemical stain was stained yellow in the cytoplasm or cell membrane. we didn't find the expressions of VEGF in the hepatocyte at instantly, 3 days and 8 weeks. At 2 weeks, the expressions of VEGF are higher than those at 1 weeks and 4 weeks. at 1 weeks , the expressions of VEGF are higher than those at 4 weeks.MRI findings: Shortly after RFA and at 3 days, They were hyperin- tense on T1WI , rim surrounding irregular hypointense and hypoint- ense on T2WI, rim surrounding irregular hyperintense. enhanced MR imaging didn't show the enhancing rim surrounding the central coagulative necrosis. 1 weak after RFA, On T1WI, the RFA lesion showed a hyperintense rim surrounded by a rim of slight hypointensity and central hypointensity, On T2WI, the RFA lesion was divided into four layers(from center to surrounding): hyperintense , hypointensity, isointensity, slight hyperinten- sity, there were surrounded by a rim of hypointensity, enhanced MR imag- ing showed the enhancing rim surrounding the central coagulative necrosis. 2 weak after RFA, On T1WI, the zone of central hypointensity, surrounded by 2 rims of hyperintense and hypointensity. On T2WI, the zone of central hypointensity, surrounded by 2 rims of hypointensity and hyperintense. enhanced MR imaging showed irregular nodular enhancing rim.4 weak after RFA, On T1WI, the zone of central hyperintense mixed hypointensity. On T2WI, the RFA lesion showed a hypointensity mixed hyperintense rim surrounded by a rim of irregular hyperintense and central hypointensity. 8 weak after RFA,On T1WI and T2WI, the RFA lesion showed isointensity same as that in normal liver tissue.Conclusions:Normal rabbit liver after radiofrequency ablation, injured liver tissue repair process is neorobiosis, inflammatory infiltration, forma- tion of granulation tissue, fibroplasias and cell regeneration. The total time is 8 weeks. VEGF is a important rol-e on injured liver repair process.MR imaging may be a important examine method to evaluate injured liver repair process。...