PET-CT Scan

A PET-CT scan is a single test that merges two types of imaging. The PET (positron emission tomography) part uses a small amount of a radioactive substance, called a tracer, to show how active different tissues are. The CT part provides detailed pictures of the body's structure. Combined, they let doctors see exactly where abnormal activity is happening within the body.

PET-CT scans are most often used in cancer care to find tumours, see whether and where cancer has spread, and check how well treatment is working. They can also help assess certain heart and brain conditions. By showing both function and anatomy at once, a PET-CT can reveal disease activity that other scans might miss, helping doctors plan the most suitable treatment.

You will usually be asked to avoid strenuous exercise and to stop eating for several hours beforehand, as food can affect how the tracer behaves; you can normally drink water. If you have diabetes, you may receive special instructions. Tell staff if you might be pregnant or are breastfeeding, and wear comfortable clothing without metal fastenings.

First, the radioactive tracer is injected into a vein, and you rest quietly for about an hour while it spreads through your body. You then lie on a bed that moves through a ring-shaped scanner that performs both the PET and CT images, which can take 30 to 60 minutes. You will need to stay still, and the process is painless apart from the initial injection.

After the scan you can usually go home, though you may be advised to drink plenty of fluids and to limit close contact with pregnant women and young children for a short time as the tracer leaves your body. A specialist reviews the combined images and sends a detailed report to your doctor. The results help confirm a diagnosis, show the extent of disease, or measure response to treatment, which your doctor will discuss with you.