FDG PET scan: what to expect

An FDG PET scan maps areas of increased glucose use to help clinicians assess disease activity alongside other information. It is usually combined with CT, which adds details about body structure and location.

FDG is a glucose-like radiotracer. After it is injected, you rest while tissues take it up, then a PET-CT scanner records the distribution. Increased uptake can occur in cancer, infection, inflammation, or normally active tissues such as the brain and heart. A scan finding is not a diagnosis by itself; your clinician interprets it with symptoms, examination, blood tests, and other imaging.

The scan may support diagnosis, staging, treatment planning, or assessment of response, depending on your clinical question.

Follow the centre's instructions about fasting, water, medicines, and arrival time. Mention diabetes, pregnancy or possible pregnancy, breastfeeding, allergies, and any difficulty staying still. Wear comfortable clothing and plan for a quiet rest period after the injection. Keep warm and limit movement during uptake if staff advise this.

Alert the team at once if you develop breathing difficulty, swelling, faintness, or intense pain. Before the scan, call if you cannot fast as instructed, have unstable blood glucose, or may be pregnant. Ask how and when results will be discussed.

Ask what the scan is intended to answer, whether contrast is planned, how to take your usual medicines, and what follow-up will happen after the report.