Which tracer is used to localize seizure site for epilepsy in PET imaging?

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

Answer: (A)

Understanding how PET helps locate a seizure focus relies on measuring brain glucose metabolism. The tracer 18F-fluorodeoxyglucose (FDG) acts like glucose and is taken up by active brain tissue in proportion to its metabolic activity. Between seizures, the epileptogenic cortex often shows reduced metabolism, so it appears as a focal area of hypometabolism on FDG-PET. This pattern helps clinicians pinpoint the region that may need targeted treatment or surgical planning.

Other tracers serve different purposes: 11C-methionine is used mainly for brain tumor imaging, not standard epilepsy localization; Tc-99m MDP is a bone-seeking agent and not used for brain PET; Ga-68 DOTATATE targets somatostatin receptors for certain tumors and is not a conventional tool for identifying seizure foci.