Xiao Bao

The preclinical study of predicting radiosensitivity in human nasopharyngeal carcinoma xenografts by 18F-ML-10 animal- PET/CT imaging

Previous studies have reported that the radiosensitivity is associated with apoptosis. Hereby, we aimed to investigate the value of 18F-ML-10 PET/CT, which selectively targeted cells undergoing apoptosis, in predicting radiosensitivity of human nasopharyngeal carcinoma (NPC) xenografts. We used CNE1 (highly differentiated) and CNE2 (poorly differentiated) NPC cell lines to construct tumor models, which had very different radiosensitivities. After irradiation, the volumes of CNE2 tumors decreased significantly while those of CNE1 tumors increased. In 18F-ML-10 imaging, the values of tumor/muscle (T/M) between CNE1 and CNE2 mice were statistically different at both 24 h and 48 h after irradiation. Besides, ΔT/M1-0 and ΔT/M2-0 of CNE2 mice were higher than those of CNE1 mice, demonstrating obvious discrepancy. Furthermore, we observed obvious changes of radioactive distribution in CNE2 group. On the contrary, T/M of 18F-FDG in irradiation group revealed no obvious change in both CNE1 and CNE2 groups. In conclusion, 18F-ML-10 animal PET/CT showed its potential to predict radiosensitivity in NPC.

Early Monitoring Antiangiogenesis Treatment Response of Sunitinib in U87MG Tumor Xenograft by 18F-FLT MicroPET/CT Imaging

Aim. It was aimed to monitor early treatment response of Sunitinib in U87MG models mimicking glioblastoma multiforme by longitudinal 18F-FLT microPET/CT imaging in this study. Methods. U87MG tumor mice were intragastrically injected with Sunitinib at a dose of 80 mg/kg for consecutive 7 days. 18F-FLT microPET/CT scans were acquired on days 0, 1, 3, 7, and 13 after therapy. Tumor sizes and body weight were measured. Tumor samples were collected for immunohistochemical analysis of proliferation and microvessel density (MVD) with anti-Ki67 and anti-CD31, respectively. Results. The uptake ratios of tumor to the contralateral muscle (T/M) of 18F-FLT in the Sunitinib group decreased from baseline to day 3 (T/M0 = 2.98 ± 0.33; T/M3 = 2.23 ± 0.36; P < 0.001), reached the bottom on day 7 (T/M7 = 1.96 ± 0.35; P < 0.001), and then recovered on day 13. The T/M of 18F-FLT uptake in the control group remained around 3.0. There was no difference for the tumor size between both groups until day 11. 18F-FLT uptakes of tumor were correlated with Ki67 staining index and MVD. Conclusion. Early therapy response to Sunitinib could be predicted via 18F-FLT PET, which will contribute to monitoring antiangiogenesis treatment.

Radiation dosimetry estimates of 18F-alfatide II based on whole-body PET imaging of mice

We estimated the dosimetry of (18)F-alfatide II with the method established by MIRD based on biodistribution data of mice. Six mice (three females and three males) were scanned for 160min on an Inveon MicroPET/CT scanner after injection of (18)F-alfatide II via tail vein. Eight source organs were delineated on the CT images and their residence times calculated. The data was then converted to human using scaling factors based on organ and body weight. The absorbed doses for human and the resulting effective dose were computed by OLINDA 1.1 software. The highest absorbed doses was observed in urinary bladder wall (male 0.102mGy/MBq, female 0.147mGy/MBq); and the lowest one was detected in brain (male 0.0030mGy/MBq, female 0.0036). The total effective doses were 0.0127mSv/MBq for male and 0.0166 mSv/MBq for female, respectively. A 370-MBq injection of (18)F-alfatide II led to an estimated effective dose of 4.70mSv for male and 6.14mSv for female. The potential radiation burden associated with (18)F-alfatide II/PET imaging therefore is comparable to other PET examinations.