PET Scan

Overview

 What is a PET scan ?

 A PET scan (Positron Emission Tomography scan) is a medical test that shows how your organs and tissues are working. It does this by using a small amount of a radioactive substance called a tracer. This tracer moves through your body and highlights areas with unusual activity. PET scans are helpful for finding diseases early, even before symptoms appear or physical changes can be seen with other scans.

What’s the difference between a PET scan, CT scan and MRI?

A CT scan shows the structure of your body using X-rays. An MRI uses magnets and radio waves to show detailed images of soft tissues. A PET scan is different because it shows how your body is working inside like how your cells are using sugar or oxygen. In many cases, doctors combine a PET scan with a CT or MRI to get both functional and structural information. This helps them make better treatment decisions.

What does a PET scan check for?

Doctors use PET scans to look for cancer, check if it has spread, or see if treatment is working. They also use it to check blood flow in the heart or brain. A PET scan can help diagnose conditions like Alzheimer’s disease, epilepsy, and heart problems. It helps doctors see which parts of the body are working normally and which are not.

When would I need a PET scan?

You may need a PET scan if you have symptoms that other tests cannot explain. If you have cancer, a PET scan can help check how far it has spread or if it has come back after treatment. If you have memory loss or seizures, a PET scan can help find out if there is a problem in your brain. After a heart attack, it can show how much damage the heart has.

Test Details

How does a PET scan work?

A healthcare worker injects a small amount of radioactive tracer into your body, usually through a vein in your arm. The tracer moves through your blood and collects in areas with high activity such as cancer cells or active parts of the brain. A special camera takes pictures of this activity. These images help doctors see what is working normally and what is not.

How do I prepare for a PET scan?

You may be asked not to eat or drink for several hours before the scan. It is important to follow your doctor’s instructions. Avoid exercise the day before the scan. If you have diabetes or take medication, tell your doctor. You might also be asked to wear comfortable clothes and remove any metal objects like jewelry.

What should I expect during a PET scan?

After the injection, you will wait for 30 to 60 minutes while the tracer spreads in your body. Then you will lie on a table that moves through a scanner. You will need to stay very still while the machine takes pictures. The scan is painless, but lying still may be uncomfortable for some people. The staff will guide you throughout the process.

How long does a PET scan take?

From start to finish, the whole appointment may take up to 2 hours. The scan itself usually takes 20 to 45 minutes. If the scan is being done with a CT or MRI, it may take a little longer. Your doctor or radiology center will tell you exactly what to expect.

What are the risks and side effects of a PET scan?

PET scans are safe for most people. The amount of radiation is low and leaves your body quickly. Side effects are rare. Some people may feel discomfort from the injection or feel anxious while lying still. If you are pregnant, breastfeeding, or have allergies, inform your doctor before the scan.

Results and Follow-Up

When should I get my PET scan results?

In most cases, results are ready in a few days. A radiologist will review the images and send a report to your doctor. Your doctor will then explain the results and discuss the next steps, if any. In urgent situations, results can be available sooner. Always follow up with your doctor after the scan.

Published 4th July 2025

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