What should you know about head pet scan?

The PET part records how tissues handle a small amount of radioactive glucose-like tracer, while CT shows anatomy and location. Together they may help assess a known head or neck cancer, look for spread, evaluate treatment response, or investigate a finding whose origin is unclear. Increased tracer uptake is not specific to cancer: infection and inflammation can also be active. A PET result therefore needs to be interpreted with examination findings and other scans. Learn about the [FDG Radiotracer](/materials/fdg-radiotracer/) and the [PET-CT Scanner](/technology/pet-ct-scanner/).

Follow the imaging centre’s fasting instructions and tell the team about diabetes, medicines, pregnancy, breastfeeding, recent illness, and difficulty lying still. Avoid strenuous activity beforehand if instructed, because muscle activity can affect tracer distribution. After injection, rest quietly while the tracer circulates. During imaging, keep your head still and follow breathing instructions. Drink fluids afterwards if the team advises this, and follow any radiation-safety guidance given for your circumstances.

Tell staff immediately about pain, swelling, or burning at the injection site, dizziness, or feeling unwell. Seek urgent help for facial swelling, wheezing, severe breathlessness, fainting, or a widespread rash after the injection. Contact your care team for new neurological symptoms such as weakness, seizure, confusion, or a severe sudden headache, regardless of the scan result.

What question is this PET-CT intended to answer? Do I need fasting or a blood glucose check? Could inflammation affect interpretation? Will contrast be used for the CT part? When will the result guide the next decision?