FDG PET scan of the brain: what to know

An FDG PET scan of the brain shows patterns of glucose use that may help assess brain function and disease activity. It is interpreted with your symptoms, examination, cognitive history, and other tests rather than in isolation.

The brain normally uses glucose, so the scan produces a map of metabolic activity. Differences between regions can provide clues about conditions affecting brain function, but reduced or increased uptake can have more than one explanation. Medication effects, blood glucose, recent activity, and the quality of preparation may influence the appearance.

If the scan is being used in an oncology setting, it may help evaluate a known disease or an area that needs further assessment. A bright or quiet area does not by itself confirm or exclude a particular diagnosis.

Follow fasting and medicine instructions from the imaging centre. Tell staff about diabetes, pregnancy or possible pregnancy, breastfeeding, recent illness, seizures, and medicines that affect alertness or glucose. Rest quietly before imaging, keep your head still, and tell the team if you feel unable to lie comfortably.

Seek urgent medical help for a new seizure, sudden weakness or numbness, trouble speaking, severe confusion, loss of consciousness, or a sudden severe headache. For appointment concerns, contact the imaging team if your glucose is not controlled or you cannot complete the preparation.

Ask what question the scan is intended to answer, whether you should take your usual medicines, how results will be compared with earlier imaging, and which symptoms should prompt immediate care.