What should you know about a PET scan for metastasis?

Before the scan, a small amount of a radioactive tracer such as [FDG Radiotracer](/materials/fdg-radiotracer/) is given. Cells that use more glucose may collect more tracer. The PET images show this activity, while the CT images show body structures and help locate the finding.

Increased uptake is not specific to cancer: infection, inflammation, healing, and some normal tissues can also appear active. A quiet area does not always exclude disease, particularly when a lesion is small or has low metabolic activity. The report is interpreted with symptoms, examination, pathology, and other imaging.

Follow the imaging centre's instructions about fasting, medicines, diabetes, pregnancy, and recent strenuous activity. Tell the team about implants, allergies, and difficulty lying still. Afterward, ask what areas were examined, whether the scan found a definite lesion or an indeterminate focus, and whether biopsy or another scan is recommended.

A [PET-CT Scan](/treatments/diagnostics-and-staging/pet-ct-scan/) is one part of staging. The images may help evaluate a known tumour, investigate symptoms, or search for a primary site when cancer has been found but its origin is unclear.

Contact the imaging or medical team if you develop a significant reaction, worsening pain, or a problem related to the injection. Seek emergency help for trouble breathing, facial swelling, collapse, new weakness, or severe confusion. These symptoms should not wait for the scan report.

What question is this PET-CT intended to answer? Could inflammation explain an active area? Does the result change the stage or treatment plan? Is tissue confirmation needed? When and how will the report be discussed with me?