Early In Vivo Monitoring Chemosensitivity To Low Dose Cisplatin Of VX2 Xenograftsin Rabbits By ¹⁸F-FDG PET/CT

Abstract :Within 48 hours by continuous two ¹⁸F-FDG PET/CT scans, we studied the radioactivity distribution of ¹⁸F-FDG and the corresponding pathological changes in the rabbit VX2 after intravenous administration of cisplatin within 36 hours.Methods:Thirty-six VX2 rabbits were randomized into four treatment groups and two control groups.There are six rabbits in every group.The first ¹⁸F-FDG PET/CT was performed the day before intravenous administration of cisplatin (7 mg/kg) and the second was 48 hours later. In the experimental groups, cisplatin administration was 6 hours,12 hours,24 hours and 36 hours before the second PET/CT imaging.The control group, without cisplatin administration, received the ¹⁸F-FDG PET/CT imaging at the same time points. The control group, with physiological saline, received the ¹⁸F-FDG PET/CT imaging at the same time points .Maximum standardized uptake value(SUVmax) was analyzed. The tumor necrosis was observed. The correlation analysis between the tumor necrosis rate and the change of SUVmax was analysed.The TUNEL technique in apoptosis in VX2 model was applied.The correlation analysis between apoptosis and the change of SUVmax was analysed. Results: 1. The results showed that there is no significant difference (P>0.05) in SUVmax at the first PET/CT. On hour 6, a significant difference in SUVmax was observed between it and other groups(P<0.01), with SUV decrease rate of (-17.02±9.07)%. The results also showed a significant difference (P<0.01) in SUVmax on hour 12 between the group and hour 6 group, with SUVmax decrease rate of (-36.13±7.5)%. The results showed a significant difference (P<0.01) in SUVmax on hour 24 between the group and hour 6 group, with SUVmax decrease rate of (-53.43±20.4)%. The results also showed a significant difference (P<0.01) in SUVmax on hour 36 between the group and hour 6 group, with SUVmax decrease rate of (-42.88±18.02)%. 2. The results showed that No significant difference in AI was found between the two control groups(P>0.05). On hour 6, a significant difference in AI was observed between it and other groups(P<0.01), with the rate of (9±2.61)%. The results also showed a significant difference (P<0.01) in AI on hour 12 between the group and other groups, with the rate of (16.68±4.58)%. The results showed no significant difference (P<0.01) in AI on hour 24 between the group and hour 36 group, with the rate of (36.15±7.89)%. The results also showed no significant difference (P<0.01) in AI on hour 36 between the group and hour 24 group, with the rate of (47.95±9.24)%.3. The results showed that on hour 6, a significant difference in the rate of tumor necrosis was observed between it and other groups(P<0.01), with the rate of (7.18±3.98)%. The results also showed a significant difference (P<0.01) in the rate of tumor necrosis on hour 12 between the group and other groups, with the rate of (17.46±2.11)%. The results showed no significant difference (P<0.01) in the rate of tumor necrosis on hour 24 between the group and hour 36 group, with the rate of (34.3±11.5)%. The results also showed no significant difference (P<0.01) in the rate of tumor necrosis on hour 36 between the group and hour 24 group, with the rate of (25±6.3)%.4. Correlation analysis:There is a significant correlation between AI and the change of SUVmax with r=-0.833. p<0.001. There is also a significant correlation between tumor necrosis rate and the change of SUVmax with r=-0.873. p<0.001.Conclusion:1. The results showed that within 36 hours there is a significant decrease in SUVmax.There is a significant increase in AI.There is a significant correlation between AI and the change of SUVmax . There is also a significant correlation between tumor necrosis rate and the change of SUVmax .And the change of FDG responses for the necrosis and apoptosis of the tumor cell.2. The study showed there is the most significant change (P<0.01) in SUVmax at 24 hours after cisplatin adminstration with PET/CT,which is the best time point as an in vivo individual chemosensitivity testing method.