Comparison of 2- and 3- ¹⁸F-Fluoro-deoxy-d-glucose for studies of tissue metabolism

2- and 3-¹⁸F-fluoro-deoxy-d-glucose were proposed as sugar analogs to study glucose metabolism in brain and heart tissues. To evaluate their usefulness, the in vivo behavior of 2-²⁸FDG and 3-¹⁸FDG was investigated in mice and rats and for 3-²⁸FDG in dogs at various times post-injection. Positron emission tomographic (PET) imaging was performed for heart and brain of anesthetized dogs with both radiopharmaceuticals. In all species studied, a higher uptake in brain, heart and kidney was observed for 2-¹⁸FDG compared with 3-¹⁸FDG. Radioactivity also cleared blood and liver more rapidly with 2-¹⁸FDG than with 3-¹⁸FDG. Estimates of brain kinetic model parameters revealed the metabolic trapping of 2-¹⁸FDG, making this agent favorable for studies of tissue metabolism, and the relative lack of phosphorylation of 3-¹⁸FDG, which makes it a potential agent for studies of glucose transport.