Objective:

To study the characteristics of

18

F-fluoromisonidazole (

18

F-FMISO) PET/CT imaging in rat C6 glioma models before and after radiotherapy

and to explore the value of 18F-FMISO PET/CT in assessing the radiosensitivity enhancement of ursolic acid (UA).

Methods:

32 rat C6 glioma models were randomly dived into four groups (8 rats in each group): group A (control group)

group B (

UA group)

group C (radiotherapy group) and group D (UA+radiotherapy group).

18

F-FMISO PET/ CT imaging was performed before radiotherapy and 24 h after radiotherapy. Tumor maximal standardized uptake value (SUVmax-T)

the lateral spinal muscle SUVmax (SUVmax-M)

the ratio of SUVmax of tumor to muscle (T/M) were calculated. All of the rats were sacrificed after radiotherapy

and pathological changes were observed by the expression of proliferation index hypoxia induciblefactor-1 (HIF-1).

Results:

At 24 h post-radiotherapy

the T/M values in groups A and B were significantly increased than that before radiotherapy (

t

=5.74

4.74;

P

0.01)

while the T/M values in groups C and D were decreased than that before radiotherapy (

t

=2.84

6.05;

P

0.05). At 24 h post-radiotherapy

the T/M value in group D was lower than that in group C

and the difference was statistically significant(

P

0.01). The expression of HIF-1 in group D was lower than that in other three groups (

P

0.01). T/M value was positively correlated with HIF-1 expression (

r

=0.78

P

0.01).

Conclusion:

UA could enhance the radiosensitivity of radiotherapy in treatment of rat C6 glioma. Hypoxic status within the tumor could be reflected by

18

F-FMISO PET/CT

and by which the radiosensitization effect of UA on C6 rat glioma could also be assessed.