Explaining PET scans and how they work

There's a number of reasons why you might have a PET scan. ^{Footnote [1]} These include:

• identifying cancer within the body
• checking if and how far cancer has spread
• assessing whether cancer is responding to treatment
• helping locate surgical sites and plan operations
• investigating conditions that affect the brain
• revealing reduced blood flow in the heart.

Medical professionals often use PET scans alongside other types of imaging such as computed tomography (CT) or magnetic resonance imaging (MRI) to produce more detailed images of your body.

Hospitals typically provide detailed instructions on preparing for a PET scan.

You may be advised not to eat anything for at least six hours before your scan and to avoid strenuous exercise for about 24 hours before your appointment.

It's normally an outpatient investigation, so you're likely to be in hospital only a few hours.

You may need to remove anything metal, so avoid wearing jewellery, belts with metal buckles or any items of clothing with metal parts, such as zips.

If you have a fear of enclosed spaces, your medical practitioner may give you a mild sedative before the scan to help you relax. Contact your doctor or the hospital beforehand and tell the radiographer when you arrive for your PET scan appointment. 

You’ll probably be asked to arrive for your appointment about an hour before your scan as the radiographer has to inject the radiotracer into a vein in your arm and give it time to collect in areas of your body. ^{Footnote [2]}  

When you’re in the department, you may be asked to go to the toilet and empty your bladder before your scan.

During the scan

The radiographer will position you in the scanner. Once the scan has started, the scanner will move slowly, taking images of the body area being scanned. You’ll need to lie really still and avoid speaking if possible so the images produced are nice and clear.

The whole process is usually pain-free and takes between thirty minutes and an hour.

It’s rare to experience side effects after a PET scan, and you’ll be able to go home the same day.

Your results probably won’t be available straight away. Instead, the hospital will send them to your doctor for you to discuss at your next appointment.

You may be offered alternative imaging tests instead of a PET scan. Your doctor is best placed to decide which one is best for you and your particular heath concern.

• MRI scan – An MRI scan uses strong magnets and radio waves to take detailed pictures of the inside of your body. It doesn't use X-rays or radiation. Instead, it works by detecting how water molecules in your tissues respond to the magnetic field, which helps create clear images of organs, muscles and other soft tissues.
• CT scan – uses X-rays to take detailed pictures of the inside of your body. Instead of just one image like a regular X-ray, the CT scanner takes many images from different angles. A computer then puts these together to create clear, cross-sectional views (like slices).
• Ultrasound scan – use high frequency sound waves to create images. It is useful for visualising soft tissues and fluid-filled structures.

If a specialist recommends a PET scan for the condition you have, it may be covered by your policy. You can make a claim on your health insurance through MyAviva, over the phone, or online.

Once we’ve confirmed your claim meets the terms of your policy, we’ll pay for the scan directly.

It’s good to have one less thing to worry about. It’s time for you to focus on your treatment and recovery without worrying about the fees.