Correlative study of ~(18)F-FDG PET/CT imaging and pathological changes of rat C6 glioma after radiotherary

Objective:To study the correlation of 18F-fluorodeoxyglucose(18F-FDG) PET/CT imaging with pathological changes of rat C6 glioma after radiotherapy.Methods:Thirty C6 glioma-bearing male SD rats were randomly divided into three groups(10 rats in each group),group A,B and C,and imaged with FDG PET/CT two weeks after inoculation of tumor cells,48h and one week after radiotherapy respectively.The ratios of SUVmax of tumor to muscles(tumor-to-muscle,T/M) and tumor volume were calculated.All rats were sacrificed after FDG PET/CT imaging for pathology and immunohistochemistry studies.Results:T/M of group B(9.23±4.56) was mildly reduced compared with group A(10.86±3.31),while group C(5.16±2.52) was significantly decreased compared with gropu A(P0.05).The amount of tumor necrosis increased with time after radiotherapy,tumor volume decreased gradually,the differentces between group A and C were significant [(8.61±6.57)cm3 vs(5.21±5.48)cm3].Microvessel density(MVD) of group B(19.5±1.96) increased slightly compared with group A(17.9±2.02),MVD of group C(8.4±1.84) was significantly decreased compared with that of group A(P0.05).Correlation analysis showed that changes of T/M between group A and C were positively correlated with tumor volume and MVD(r=0.83,0.68,all P0.05);while changes of T/M between group A and B were only positively correlated with tumor volum(r=0.76,P0.05).Conclusion:The changes of 18F-FDG uptake of rat C6 glioma in the early 48h after radiotherapy were only relevant to tumor volume,but were closely related to pathological changes one week later.