What should you know about a whole body PET scan?

Before the scan, a small amount of FDG radiotracer is given, usually through a vein. Cells that use more glucose may take up more tracer, and the PET images show this activity. CT adds a detailed map of body structures, allowing the team to compare activity with anatomy.

In oncology, the scan may help find disease, assess spread, guide a biopsy, or evaluate treatment response. Increased uptake is not specific to cancer: infection, inflammation, normal organ activity, and recent treatment can also affect the images. A PET result must be read with your history and other tests.

Follow the imaging team’s instructions about eating, drinking, medicines, diabetes, and exercise. Wear comfortable clothing and tell staff if you may be pregnant or are breastfeeding. Plan for time to rest quietly after the tracer is given and to remain still during imaging. The team will explain when normal activities can resume.

Tell staff immediately if you feel unwell during or soon after the injection, develop swelling or pain at the injection site, or notice breathing difficulty. After leaving, seek urgent help for severe breathing problems, fainting, or rapidly worsening symptoms. Contact the imaging team if you could not follow preparation instructions, because this may affect the appointment.

Ask what the scan is intended to answer, whether you need a PET-CT scan, how diabetes or medicines affect preparation, and when results will be discussed. Ask whether findings could change staging or the next test, particularly when lymphoma or cancer of unknown primary is being investigated.