Radionuclide tests are considered safe. However, during the test you will be exposed to some radiation.
Every day we are exposed to radiation which occurs in the environment. Our risk of cancer can increase if we're exposed to too much, but the amounts used in these tests are small.
Your doctor will suggest you have the test if they feel it's safe and appropriate.
Types of radionuclide tests
There are two main types of radionuclide tests:
- a myocardial perfusion scan
- a computerised tomography (CT) scan.
You may hear different names being used to describe these tests. If the name of your test isn't mentioned below, ask your doctor what your test involves.
The radiographer who performs the test will tell you what to expect during the test and will talk to you throughout.
Myocardial perfusion scan
This is also known as a thallium scan, MIBI scan, MPS or technetium scan. A camera takes pictures to:
- look at the pumping action of your heart
- look at the flow of blood to your heart muscle
- see how your heart functions when it has to work harder - for example, when you're being more active, or
- help diagnose coronary heart disease (CHD).
Learn what happens during a myocardial perfusion scan.
When might I be offered this test?
You may be offered this test if you haven't previously been diagnosed with angina and you have had episodes of chest pain. Your doctor may suspect you have CHD, which this test will help diagnose.
You may also be offered this test if you have already been diagnosed with CHD and your doctor wants to find out if you'll benefit from having a procedure such as angioplasty or coronary bypass graft.
CT scans (computerised tomography)
A CT scan is also known as a CAT scan. It's a sophisticated type of X-ray, which can produce detailed images of your heart. It can look at:
- the pumping action of your heart
- the structure of your heart - its muscle, valves and coronary arteries (the arteries that supply your heart muscle with blood and oxygen)
- the flow of blood through your heart and your coronary arteries.
A CT scan can see how well your heart is working and can help to diagnose various heart conditions such as an enlarged heart, heart valve problems or coronary heart disease (CHD).
This test can also see if there is a build-up of excess calcium within your coronary artery walls. Your doctor will calculate the result into a score – if yours is high, they may want to monitor you more closely.
What happens during a CT scan?
Usually, at the start of the scan, a type of dye (called contrast) is injected into a vein in your arm. This allows the camera to easily see the heart's structure and blood flow. This causes a warm, flushing sensation throughout the body lasting a few seconds which some people may find strange, but isn’t painful.
You will then be asked to lie on a bed which passes through the CT scanner. The length of the test depends on the type of scanner used and why you are having the scan.
When might I be offered this test?
You may be referred for a CT scan if doctors are unclear of the cause of your chest pain.
If your doctor thinks a diagnosis of CHD is likely, they are more likely to offer you a myocardial perfusion scan or a coronary angiogram instead.
Want to find out more?
Tests for heart conditions booklet
This booklet describes the special tests that are commonly used to help diagnose heart diseases.
Some of the tests are also used to assess the current condition of people who have already been diagnosed with heart disease.