COMPARATIVE PET IMAGING OF EXPERIMENTAL-TUMORS WITH BROMINE-76-LABELED ANTIBODIES, FLUORINE-18-FLUORODEOXYGLUCOSE AND CARBON-11-METHIONINE

The potential of a Br-76-labeled anti-carcinoembryonic antigen monoclo nal antibody (MAb), 38S1, as a tumor-imaging agent for PET was investi gated in a comparative experimental study with [F-18]fluorodeoxyglucos e ([F-18]FDG) and L-[methyl-C-11]methionine ([C-11]Met). Methods: The three radiotracers were administered to nude rats carrying subcutaneou s xenografts or liver metastases from a human colonic carcinoma. Trace r biodistribution was evaluated by PET imaging and radioactivity measu rement of dissected tissues and also by whole-body autoradiography for subcutaneous xenografts. Results: For PET imaging of subcutaneous tum ors, Br-76-38S1 proved superior to the other radiotracers. Tumor-to-ti ssue ratios were, except for the tumor-to-blood ratio, generally highe r for Br-76-labeled MAb than for [F-18]FDG and [C-11]Met. Liver metast ases were imaged with PET using both Br-76-38S1 and [F-18]FDG, and the metastases-to-liver ratios of dissected samples were not significantl y different for the two radiotracers. Conclusion: The tumor-imaging ca pacity of Br-76-labeled MA6 38S1 was superior to [F-18]FDG and [C-11]M et in the subcutaneous tumor model, whereas Br-76-38S1 and [F-18[FDG w ere equally successful for the identification of liver metastases.