What are PET-CT scans used for?

A PET-CT joins metabolic information from a tracer with CT pictures of anatomy. It may help investigate a suspicious finding, search for disease in more than one body area, support staging, or identify a suitable area for biopsy. The scan can also provide a baseline before treatment and help assess whether activity has changed afterward.

Uses vary by cancer type and by the question being asked. FDG activity is not exclusive to cancer: infection, inflammation and normal organs can also appear active. A quiet area does not always exclude disease. The report is interpreted with examination findings, pathology and other imaging.

The imaging centre will explain when to stop eating, what fluids are allowed and whether medicines need adjustment. Tell the team about diabetes, pregnancy or possible pregnancy, breastfeeding, recent illness and difficulty lying still. After injection, you usually rest quietly before images are taken. Bring earlier scans and reports when requested.

The [PET-CT Scan](/treatments/diagnostics-and-staging/pet-ct-scan/) page explains the appointment. You can also read about the [FDG Radiotracer](/materials/fdg-radiotracer/) and [PET-CT Scanner](/technology/pet-ct-scanner/).

During or after the appointment, report breathing difficulty, throat or facial swelling, faintness, severe dizziness, or increasing pain and swelling around the injection site. For a scan result, follow the scheduled review rather than trying to diagnose yourself from the images. Contact the treating team sooner if new symptoms are severe or rapidly worsening.

What question is this scan intended to answer? Could the result change staging or the treatment plan? Will I need a biopsy or another type of imaging? When and with whom will I discuss the report?