What tracer is used to evaluate glucose metabolism in PET imaging?

• A. 18FDG
• B. 11C-Methionine
• C. Tc-99m MDP
• D. Ga-68 DOTATATE

Answer: (A)

Evaluating glucose metabolism in PET uses a tracer that behaves like glucose but gets trapped inside cells after phosphorylation. This is 18F-FDG: a glucose analog that enters cells via glucose transporters and is phosphorylated by hexokinase to FDG-6-phosphate, but it cannot proceed through glycolysis, so it accumulates where glycolytic activity is high. The PET signal comes from the radioactive fluorine-18, highlighting tissues with increased glucose uptake—common in many cancers and inflammatory processes. Other tracers shown are used for different purposes: 11C-methionine tracks protein synthesis, Tc-99m MDP is used for bone imaging, and Ga-68 DOTATATE targets somatostatin receptors in neuroendocrine tumors. Therefore, for glucose metabolism imaging, 18F-FDG is the tracer of choice.