Longitudinal evaluation of tumor metastasis by an FDG-microPET/microCT dual-imaging modality in a lung carcinoma-bearing mouse model

Background: Histological methods are used to define the growth and response to various treatments of lung carcinoma in mice. The aim of the study was to evaluate a quantitative and 3D-tomographic microPET/microCT dual-image modality using 18F-fluorodeoxyglucose (FDG) to monitor the tumor progression in an experimental metastasis mouse model. Materials and Methods: Six normal mice were subjected to FDG-microPET/microCT image scan to present the normal thorax morphology. Twenty-one 8-week-old male C57BL/6 mice were inoculated with 1×10⁶ Lewis lung carcinoma cells (LLC1) through the lateral tail vein. FDG-microPET/microCT scans were performed on days 0, 5, 9, 13 and 18 (n=6) to monitor the growth of the tumor. MicroPET and microCT images were further used to monitor the metastasis of the lung carcinoma to the liver. Fifteen mice were sacrificed for biodistribution on days 0, 5, 9, 13 and 18 after the inoculation of lung carcinoma cells. Results: The FDG-microPET/microCT dual-image modality showed that the growth of the tumor could be monitored longitudinally. The standard uptake value (SUV) of FDG increased from 0.63±0.05 on day 0 to 1.03±0.15 on day 18, reflecting the growth of the tumor in mice. The tumors located in the lung and liver could be clearly visualized by the fusion of microPET and microCT images, and further confirmed by whole-body autoradiography or H&E stain. Conclusion: By FDG-microPET, the increase in SUV provided an alternative for assessing the growth of a tumor in vivo. Our results suggest that the growth progression of lung carcinoma can be identified using the FDG-microPET/microCT dual-image modality longitudinally in mice.