ABSTRACT
ObjectiveTo study the relationship between 18F-FDG uptake and tumor cell density,glucose transporter expression,cellular proliferation and angiogenesis before and after radiotherapy in C6 glioma rats.MethodsThirty C6 glioma-bearing male SD rats were randomly divided into three groups:A,B and C ( 10 rats in each group).Two weeks later,18F-FDG PET/CT was performed in group A.In groups B and C,18 F-FDG PET/CT was performed at 48 h and 1 week after radiotherapy,respectively.The ratio of SUVmax of tumor to muscle (T/M) was calculated.HE staining,immunohistochemical staining and Western blot were used to measure tumor cell density,Ki67 labeling index ( LI),microvessel density ( MVD),Glut-1 and VEGF expression quantitatively.The one-way analysis of variance and bivariate correlation analysis were used to compare the changes of each indicator and evaluate the correlation between T/M and biological indicators,respectively.Results Significant differences of T/M,tumor cell density,Ki67 LI,MVD,Glut-1 and VEGF among groups A,B and C were observed ( F =6.77,60.66,104.56,95.49,9.13,24.48,respectively,all P ＜0.05).Least significant difference (LSD) test showed that there was no significant difference between group A and B in T/M,tumor cell density and Ki67 LI ( 10.86 ± 3.31,730.50 ± 78.93,20.02 ± 2.14 vs 9.23 ± 4.56,672.70 ± 92.98,18.56 ± 2.26).However,the indicators of group C (5.16 ± 2.52,355.60 ± 72.62,7.81 ± 1.76 ) were significantly decreased compared with those of groups A and B (all P ＜0.05 ).MVD and Glut-1 expression of group B increased slightly compared with those of group A ( 19.50 ± 1.96,0.20 ± 0.09 vs 17.90 ± 2.02,0.15 ± 0.04),but the difference was not statistically significant.Nevertheless,the two indicators were significantly decreased in group C ( 8.40 +1.84 and 0.07 ±0.06,P ＜0.05).VEGF expression in group B (0.42 ±0.13) was significantly higher than that in groups A and C (0.17 ±0.04 and 0.16 ± 0.09) ( both P ＜ 0.05 ).The changes of T/M were positively correlated with the changes of tumor cell density between groups A and B ( r =O.81,P ＜ 0.05 ).Changes of T/M were positively correlated with the changes of tumor cell density,Ki67 LI,MVD and Glut-1 between groups A and C (r =O.83,0.71,0.68,0.62,all P ＜ 0.05 ).ConclusionsThe changes of 18 F-FDG uptake in C6 glioma rats were only correlated to the changes of tumor cell density at 48 h after radiotherapy.However,the changes of 18F-FDG uptake closely correlate to the changes of a variety of biological indicators at 1 week post radiotherapy.