Cardiac computed tomography (CT) scanning is a test used to view the heart and coronary arteries. It uses a combination of X-ray and computer technology to detect blockages in the arteries and /or calcification in the artery walls - the factors which contribute to angina.
Cardiac CT scans can also be used to:
The results of a cardiac CT scan can be used in combination with other test results to help determine and confirm the extent of any coronary artery disease. Knowing that you have early stage disease – even before you have symptoms – means that you can modify your lifestyle risk factors and prevent or slow the worsening of your condition.
Computed tomography has been in development for many years and is continually being refined and enhanced. There are several types that you might encounter.
Calcium-score screening heart scan. Also known as an electron-beam computed tomography (EBCT) or multi-detector computed tomography (MDCT), a calcium-score screening heart scan is an advanced form of CT screening. It works at 10 times the rate of ordinary CT scans and is used to detect calcium deposits in the plaque in the coronary arteries – known as calcification.
Calcium should not be present in healthy arteries. Its presence contributes to the narrowing of your arteries. When this narrowing occurs in the coronary arteries (the arteries that supply blood to your heart muscles), you’re at increased risk of experiencing the symptoms of coronary artery disease.
If you’re at moderate risk of coronary artery disease but showing no symptoms, this test may be recommended because it reveals the calcification of your arteries in a way that other tests may not.
You can then take strong preventive action through lifestyle measures and, in some cases, medication, to stop or slow further damage.
On the other hand, if you’re at high risk of coronary artery disease, this test may not be for you because your condition can be determined in other ways. And in any event, a low calcium score does not mean you’re safe from having a heart attack.
Coronary CT angiography (CTA). This is another newer CT technique that involves taking three-dimensional pictures of your heart and major blood vessels. These are then used to determine the degree of plaque build-up in the coronary arteries.
Coronary CTA involves use of a contrast agent – generally iodine-based – that is injected into your arm via an intravenous drip. The contrast agent helps the images show up more clearly. While it is still generally accepted that a more invasive test, a form of cardiac catheterisation known as coronary angiography, can provide a clearer and more accurate picture of the arteries in question, use of CTA is increasing.
Total body CT scan may be offered to provide you with a picture of your overall health, including your heart health, with the claim that it can identify future problems. This is still an unproven claim. Using a technology can do you more harm than good by finding insignificant abnormalities which may result in unnecessary surgery or treatments, not to mention the high dose of radiation it entails. In addition, it may provide no more insight into your health than would be revealed by looking closely at other signs and symptoms.
A CT scan will be performed in a hospital or medical imaging clinic and usually takes up to 30 minutes. It is non-invasive and painless.
You’ll be asked to remove clothing and any jewelry you’re wearing from the waist up and given a hospital gown. The test is then taken when you are lying face up on an examination table while X-rays are passed through your body. The test usually lasts about 30 minutes.
In some cases you may be required to fast for four hours or so before the test and/or to avoid stimulant drinks such as caffeine-containing coffee, tea or cola. This is because the images of your heart are better quality if it’s beating slowly – and caffeine can increase your heart rate.
For the same reason, you may be asked not to take certain medications or be given a medication known as a beta-blocker which slows your heartbeat before the test.
A cardiac CT can show an accurate three-dimensional image of your heart and its surrounding arteries. This will in turn enable insights into what, if any, degree of coronary artery disease you have, and suggest some preventive and treatment options.
If you have a calcium-score screening heart scan, the results will include a ‘score’ indicating the total calcium buildup in your coronary arteries. A score of one to 10 suggests that your arteries have little or no calcification but doesn’t guarantee a low risk of heart attack; a score of 11 to 400 demonstrates a mild to moderate calcium buildup while a score of over 400 shows that you have significant calcification and are at high risk of experiencing coronary artery disease symptoms including heart attack. You’re also at high risk of experiencing a stroke.
Risks of coronary CT scanning are low, apart from radiation exposure, which is lower as machines improve and their speeds increase.
If a contrast agent such as iodine is used, there is also a small risk of an allergic reaction to it. So it’s important to let your doctor or technician know of any allergies you have before you take the test.
Next: Coronary angiographyTop of page
This information has been developed and reviewed for Bupa by health professionals. To the best of their knowledge it is current and based on reputable sources of medical research. It should be used as a guide only and should not be relied upon as a substitute for professional medical or other health professional advice.
Bupa Australia Pty Ltd makes no warranties or representations regarding the completeness or accuracy of the information. Bupa Australia is not liable for any loss or damage you suffer arising out of the use of or reliance on the information. Except that which cannot be excluded by law. We recommend that you consult your doctor or other qualified health professional if you have questions or concerns about your health. For more details on how we produce our health content, visit the About our health information page.
Last published 31 October 2011