What tracer is used in a PET scan?

FDG behaves in a way that allows the PET camera to follow glucose-related activity. After it is given, you rest quietly while the tracer spreads. The scanner detects signals from the radiolabel and turns them into an activity map. The amount and timing are selected by the nuclear medicine team. Activity is not exclusive to cancer: normal organs, inflammation and infection may also take up tracer. Learn more about [FDG Radiotracer](/materials/fdg-radiotracer/).

Follow the centre's instructions about fasting, permitted fluids, exercise and medicines. Tell staff about diabetes, pregnancy, breastfeeding, allergies and recent treatment. Keep warm and relaxed if instructed, because strenuous activity or shivering can influence muscle activity on the images. Afterward, follow the team’s advice about fluids, urination and contact with others. The [PET-CT Scanner](/technology/pet-ct-scanner/) records the tracer pattern.

Tell staff at once if you feel faint, develop a rash, or have trouble breathing after the tracer. Seek emergency care for swelling of the face or throat, severe breathing difficulty or collapse. Ask before the appointment how to report a delayed reaction or a preparation problem.

Ask which tracer will be used, whether your medicines or diabetes plan need adjustment, and how pregnancy or breastfeeding changes the instructions. Ask when you can eat, exercise and return to normal activities.