This study is to explore the feasibility of using 18F-FDG PET/CT as an in vivo individual chemosensitivity testing method. Forty-two VX2 rabbits bearing a total of 84 tumors were randomized into treatment group (n=32) and control group (n=10). 18F-FDG PET/CT was performed the day before intravenous administration of cisplatin (4 mg/kg) and at 95?100 min (Day 0)

Day 1

Day 7

and Day 14 afterward. The control group

without cisplatin administration

received the 18F-FDG PET/CT imaging at the same time points. Maximum standardized uptake value (SUV) was analyzed. The animals on Day 7 with a tumor volume of at least twice as larger than Day 0

were regarded as the sensitive group (SG)

while the others the insensitive group (ISG). The results showed that a significant difference (P<0.05) in SUV on Day 0 between SG and ISG

with SUV decrease rate of (?48.96±12.27)%

(21.26±18.26)% and (7.16±13.47)% for SG

ISG and the control

respectively. No significant difference in tumor volume was found among the three groups pre-therapy and on Day 0 and Day 1. On Day 7

however

the tumor volume with SG was smaller than with ISG

in a significant difference of P<0.05

while no significant difference was seen between ISG and the control on Day 7. On Day 14

no significant difference was observed among the tumor volume of the three groups (P>0.05). On Day 7 and Day 14

significant differences were seen in tumor necrosis rate in SG and ISG (P<0.05)

but no significant differences were seen between ISG and the control. Paraffin section stained with haema-toxylin and eosin of sections obtained at different time showed that the number of viable tumor cells in sensitive group diminished than ISG and the control

and inflammation and necrotic cells were increased on Day 7 and Day 14. The study showed that 18F-FDG PET/CT can be used as an in vivo chemosensitivity testing method. According to the decrease rate when cisplatin adminstration

PET can early in vivo sensitively differentiate the sensitive and insensitive tumors.