Micro-PET imaging of angiogenesis based on 18F-RGD for assessment liver metastasis in colorectal cancer

Abstract Background: This study aimed to explore the feasibility of 18 F-AIF-NOTA-E[PEG4-c(RGDfk)]2 (denoted as 18 F-RGD) PET quantitative parameters to distinguish the angiogenesis in colorectal cancer (CRC) mice which has different metastatic potential. Methods: Animal models of CRC liver metastases were established by implanttation of human CRC cell lines LoVo and LS174T via intrasplenic injection. Radiotracer-based micro-positron emission tomography imaging of animal model was performed and the uptake of 18 F-RGD tracer in the tumor tissues were quantified as tumor-to-liver maximum or mean standardized uptake values ratio. Pearson correlation was used to analyze the relationship between radioactive parameters and tumor markers. Results: The SUVmax ratio and SUVmean ratio of LoVo model was significantly higher than LS174T ones in both liver metastasis and primary tumor lesions (P ＜ 0.05 ). A significantly difference was observed in both VEGF and Ki67 expression between LoVo and LS174T primary tumors (P ＜ 0.05 ). The T/L SUVmean or SUVmax ratio of 18 F-RGD showed a significantly correlation with VEGF expression, but weakly correlated with Ki67 expression. The areas under the ROC curves of 18 F-RGD SUVmean ratio for differentiate LoVo from LS174T tumor was 0.801. Conclusions: The T/L SUVmean ratio of 18 F-RGD is a promising parameters for tumor imaging and monitoring angiogenesis process in CRC xenograft mice model.