Imaging Pancreatic Carcinoma Model With 11C-acetate: A Comparision Study With 18F-FDG Using MicroPET

Purpose:The current study intended to evaluate the significance of 11C-acetate as a tracer for detection of pancreatic carcinoma.Methods:immunodeficiency BALB/c-nu nude mice were inoculated subcutaneously with BxPC-3 human pancreatic carcinoma cell.Begun at the week 2 after inoculation, 11C-acetate and 18F-FDG micro PET(mPET)imaging were performed on mice every week thereafter.For 11C-acetate imaging,a continuous 2 10-min mPET scans were preformed at 10 rain after a 18.5 MBq 11C-acetate injection via the tail vein. For 18F-FDG imaging,a 10-min mPET scan at 1h and a delayed scan at 3h were performed after a 7.4 MBq 18F-FDG injection via the tail vein.By drawing regions of interest(ROI)on the tumor and adjacent area,tumor to non-tumor ratio(T/NT) were calculated on the transaxial tomographic images in both 11C-acetate and 18F-FDG imaging.The mice were sacrificed under anesthesia and the whole tumor tissues were removed after the last scan.The tumor proliferation was evaluated by proliferating cell nuclear antigen(PCNA)immunohistochemistry.Results tumors became visible at the second week after inoculation and grew slowly thereafter. Detectable accumulation in the tumor could be seen at the 3^rdweek for 11C-acetate and 4^thweek for 18F-FDG in the mPET scans.Peak T/NT ratio was obtained at 5^th week for 11C-acetate and at 4^thweek for 18F-FDG.T/NT ratio in 11C-acetate mPET was less than that in 18F-FDG mPET within the same week,but no signification difference was found(P＞0.05).Tumors in 11C-acetate images were visually clearer than those in 18F-FDG ones.No signification correlation was found between the T/NT ratio in 11C-acetate mPET and that in 18F-FDG mPET,None of tumor size, T/NT ratio of 11C-acetate and T/NT ratio of 18F-FDG showed significant correlation with tumor PCNA expression.Conclusion:Pancreatic tumor xenografts could be earlier detected and a better tumor contrast was obtained by 11C-acetate mPET compared to 18F-FDG mPET. 11C-acetate might be a promising candidate for imaging pancreatic carcinoma.