68Ga-Chloride PET Reveals Human Pancreatic Adenocarcinoma Xenografts in Rats—Comparison with FDG

Purpose The aim of the study was to compare 68 Ga-chloride with 2-[ 18 F]fluoro-2-deoxy- d -glucose (FDG) for the imaging of pancreatic xenografts. Procedures Rats with subcutaneous human pancreatic adenocarcinoma xenografts were evaluated in vivo by dynamic positron emission tomography (PET) and ex vivo by measuring radioactivity of excised tissues and by digital autoradiography of tumor cryosections. Results Both tracers were capable of delineating all subcutaneous tumors from surrounding tissues by PET. The standardized uptake values of tumors by PET were 0.9 ± 0.3 (mean ± SD) for 68 Ga-chloride ( n = 13) and 1.8 ± 1.2 for FDG ( n = 11). Ex vivo studies showed tumor-to-muscle ratio of 4.0 ± 0.3 for 68 Ga-chloride ( n = 4) and 7.9 ± 3.2 for FDG ( n = 4). Conclusions 68 Ga-chloride delineated subcutaneously implanted pancreatic adenocarcinoma xenografts by PET, but the uptake was lower than FDG. Further studies to clarify the value of 68 Ga-chloride for PET imaging of tumors are warranted.