A myocardial perfusion scan is a nuclear medicine scan. Like other nuclear medicine scans, it involves being injected with a very small amount of a radioactive substance - what we call, a tracer or radiotracer. While it's there, it gives off gamma rays which are then picked up by a special camera which allows us to diagnose what the issue may be. This scan tells us how well your heart muscle is being supplied with blood and is sometimes called a technetium scan, or a thallium scan. 

Before your scan

Before your scan, we'll look at your medical history and symptoms with you so we can select the most suitable method for your test. We'll also explain the scan, how it works and answer any questions you may have. 

Preparing for your scan

When you come in for your scan, we'll need you to provide a list of all the medicines you currently take. This includes anything from prescription medicines to inhalers, sprays and over-the-counter, non-prescription medicines. If you can't bring a list, just bring all the medicines you're currently taking - and the packaging they came in - with you. 

If you need to take any of your regular medications while you're with us for your scan, please bring them with you.  

48 hours before your appointment

If Dipyridamole (also called Asasantin or Persantin) is one of your usual medications, you will need to stop taking this 48 hours before the scan. We'll discuss this with you when you call to arrange your appointment. 

All other medications can be taken as normal. 

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. 

Two hours before your appointment

We ask that in the two hours before your appointment:

  • do not eat any solid foods
  • drink clear fluids only

People with diabetes

If you are diabetic, you won't need to change anything about your diet or medication for the scan. Please all the medications and snacks you'll need with you. 


Please wear loose, comfortable clothes. This allows us to attach monitoring leads and blood pressure equipment to your body. Trousers are best because we may ask you to do some gentle exercise during the scan. You should also wear comfortable, flat shoes or trainers. 


We advise that you do not bring children with you to your appointment. This avoids any unnecessary radiation exposure they may encounter in the nuclear medicine department. 


If you are pregnant or think you may be, please tell us before your scan - even small amounts of radiation can harm unborn babies. 

If you're breastfeeding, you can still have the scan but it's important that you contact us for advice before you come in for the scan. 

What to expect during your scan

1. We'll put a small tube into a vein in your arm so we can give you medication to prepare your heart for the scan. The medication can have side effects such as mild shortness of breath, or a feeling of warmth in the body, but it shouldn't last more than a few minutes. After that, we'll also use the tube to put the tracer into your body. This is what allows us to take images of your heart. 

2. Depending on your medical history, we'll then ask you to pedal (seated) on an exercise bike for about four to six minutes. Don't worry if you can't do this for some reason, we'll still be able to do the scan. 

First scan

You can do the scan while lying down or reclining in a chair, either way we will ask you to be as still and relaxed as you can, with your arms away from your chest. The scanner is positioned close to your chest before the scan begins and it will take about 15 minutes. The scanner won't cause you any discomfort and the machinery is very quiet and your body will not be enclosed at any point. Staff will be close to you at all times. 

Take a break

If it's decided that you can have a second scan, you will be able to take a break at this point and have a drink or light snack, if you wish. 

Second scan

Depending on your medical history and the results of your first scan, we usually take a second scan after you've had between two-four hours rest. Comparing this resting scan with your first scan provide additional information about your heart. 

After this scan, we'll check your images and then let you know when your test has finished. 

Two-day scans

Depending on your personal and medical history, we may need you do your scans on two separate days. This allows us to make sure that the total radiation exposure and any associated risks are kept as low as possible. If this is the most appropriate way to carry out your scan, we'll discuss this with you when you call to book your appointment. Each of the two visits to the department will be about 60 to 90 minutes long. 



There is a very small risk that the medication or exercise involved in this scan could cause abnormal heart rhythm or a heart attack, although this risk is about 1 in 20,000. The risk of death is also about 1 in 20,000. 

If you can walk at a medium pace for six minutes without problem, then the risk is even lower. We'll find out about any risk to you from exercise before we start the test and answer any questions you may have. 


The tracers we use produce a very small amount of radiation, similar to that used in a CT scan. The risk of fatal cancer occurring because of this radiation is very low, about 1 in 10,000 to 1 in 1,000. This level of risk is very small compared to your overall lifetime chance of getting cancer. 

Find out more about our nuclear medicine test and scans service

There are currently no related conditions associated with this test.


Your scan will take place at either Royal Brompton or Harefield hospital. Find out more about other nuclear tests, who is likely to take care of you, and how to get to hospital.