Imaging a pancreatic carcinoma xenograft model with 11C-acetate: a comparison study with 18F-FDG.

PURPOSE: Pancreatic carcinoma is a malignant tumor with poor prognosis and its early detection is still a clinical problem. The aim of this study was to evaluate the efficacy of carbon-11-labeled acetate (11C-acetate)-positron emission tomography (PET) for the detection of pancreatic carcinoma in a BxPC-3 human pancreatic carcinoma xenograft-bearing immunodeficiency BALB/c-nu nude mice model.

METHODS: Whole-body 11C-acetate and fluorine-18-labeled fluorodeoxyglucose (F-FDG) micro-PET imaging were performed weekly on BxPC-3 human pancreatic carcinoma xenograft-bearing BALB/c-nu nude mice from the 2nd week after tumor cell inoculation. Regions of interest method and tumor-to-nontumor ratio (T/N ratio) were used for semiquantitative evaluation. Tumor proliferation was evaluated by immunohistochemistry analysis of proliferating cell nuclear antigen.

RESULTS: Radiotracer accumulation in the tumor xenografts could be detected 1 week earlier in 11C-acetate-PET than that in 18F-FDG-PET. Peak T/N ratio was obtained at the 5th week in 11C-acetate-PET and at the 4th week in 18F-FDG-PET. T/N ratio in 11C-acetate-PET was lower than that in 18F-FDG-PET during the same period. By visual evaluation, tumor xenografts were more easily observed in 11C-acetate-PET than in 18F-FDG-PET in most of the mice. Linear correlation analysis indicated T/N ratios in C-acetate-PET had no significant correlation with those in 18F-FDG-PET. Tumor size, T/N ratio in 11C-acetate-PET, and T/N ratio in 18F-FDG-PET were not found to be significantly correlated with tumor proliferating cell nuclear antigen expression.

CONCLUSION: 11C-acetate-PET imaging can be used for the detection of pancreatic carcinoma. In the early stage of tumor growth, 11C-acetate-PET has better detectability than that of 18F-FDG-PET.