A PET-CT rubidium scan provides us with detailed information about how your organs look and how they're functioning. PET and CT are two different scans which involve:

PET: a PET (positron emission tomography) scan uses a mild, radioactive dye called rubidium to highlight the areas of your body where cells are more active than normal. It can show us abnormal activity. 

CT: a CT scan uses a number of x-rays from around the body to create a three dimensional picture of tissue and organs.  

Together, a PET-CT scan can show us how your body is functioning and, more specifically, whether there's a blood supply shortage or blockages. 

Technically, this appointment will involve two scans. They are:

  • Resting rubidium PET-CT scan - lasting 10-15 minutes, this scan provides us with a baseline measurement of the blood supply to your heart
  • Stress rubidium PET-CT scan - again, 10-15 minutes long, this scan gives us a measurement of the blood supply to your heart during exercise (stress)

All PET-CT scans are carried out at 77 Wimpole Street, London.

Before the scan

24 hours before your appointment

Because caffeine can interfere with the medications we use and affect the result of your test, we ask you not to eat or drink anything containing caffeine for 24 hours before your scan. This includes:

  • tea or coffee, including green tea and decaffeinated tea or coffee because they all contain small amounts of caffeine
  • chocolate, including drinking chocolate
  • cola and other drinks, such as energy or sports drinks containing caffeine (check the label)
  • cold or pain relief medications that may contain caffeine (check the packaging)

Any drinks that don't contain caffeine are fine. This includes water, milk, fruit juice, soya milk, and any herbal infusions that do not contain caffeine. 

Please have a light breakfast on the day of your scan, but remember it must be without caffeine.

During the scan


For the resting rubidium PET-CT scan, we'll insert a small tube into a vein and inject a small amount of rubidium into it. This allows the scanner to take pictures of the blood flow to your heart.


For this part - the stress rubidium PET-CT scan - we'll give you a drug which increases the blood flow to your heart. During this time, we'll do another scan to see how the blood flow to your heart us under stress conditions. 

You'll need to lie on a scanner couch for about 30 minutes throughout all of this and we will ask you to keep as still as possible during this time. 

After the scan

The radiation dose from this procedure is so small, you won't need to make any changes to your normal routine once the scan has finished.

There are currently no related conditions associated with this test.


77 Wimpole Street


Monday to Friday, 8am to 9pm 
Saturday, 9am - 5pm 

Tel: +44 (0)20 3811 7642