Your cardiac CT scan

CT stands for Computerised Tomography. A CT scanner is a ‘doughnut shaped’ machine that uses x rays to produce more in depth images of the body. Instead of producing a single picture like an x ray, the scanner produces many pictures in ‘slices’ through the body.

To produce the pictures, an x ray machine inside the scanner rotates, firing off a beam of x rays that passes through the body to a row of detectors on the opposite side.

A computer then transforms the signal received by the detectors from the x rays into images which are displayed on a screen.

During your Cardiac CT scan, images will be taken of your heart and coronary arteries. This allows us to see any narrowing or blockages of the arteries around your heart.

Please check your appointment letter for specific information regarding your scan.

You may be required to have a blood test prior to your CT scan. Your appointment letter will explain if this is required.

If you are taking medication for diabetes, e.g. Metformin / Glucophage, this may need to be stopped before your scan. If you are diabetic, please ring the telephone number on your appointment letter for further advice.

Please do not eat anything for 2 hours prior to your scan and avoid tea and coffee on the day of your scan.

Prior to the scan, a member of staff will check your heart rate and blood pressure. During the scan; a Radiologist (the doctor overseeing your procedure) may give you some medication to temporarily slow your heart down. You may also be given a spray medication to temporarily dilate the coronary arteries, to help improve the scans accuracy.

For the majority of cardiac scans, we need to give you an injection of contrast ‘dye’ during the scan. This helps us see your coronary arteries.

This dye contains iodine, which some people are allergic to. If you have a known allergy to iodine, please contact us prior to your appointment.

If you have any special circumstances, or requirements regarding the preparation, please let us know.

You may need to spend between 30 minutes to 2 hours (though 2 hours is rare) in the department.

We will try to keep to your appointment time, but occasionally we have to scan patients urgently at short notice. This means that your appointment may be delayed. We will let you know if this is the case when you arrive for your appointment.

You may be asked to undress and put on a hospital gown. If you wear loose clothing that contains no metal (like zips, buckles or buttons) you may not have to wear a hospital gown. Please also consider removing jewellery and leaving any valuables at home.

• When you enter the room you will be asked to lie on your back on a narrow, slightly concaved bed. ECG leads will be placed on your chest so that we can synchronize the scanner with your heartbeat.
• The scanner looks like a large doughnut. You will not be enclosed in a tunnel. The radiographer will be able to see, speak to and hear you throughout the examination.
• As the scan commences, the scanner will make a whirring noise and the bed will move in and out of the scanner.
• You will be asked to hold your breath for a few seconds as each picture is taken. You should not feel any pain during the scan.
• If you are having an injection, you might have a hot flush and get a metallic taste in your mouth. Some patients also experience a sensation like they are wetting themselves; this is expected and these sensations pass within moments.

If you have any questions at all about your scan, please do not hesitate to ask the radiographer.

If you have had the injection of dye and / or the medication you will need to stay in the department for at least 15 minutes after your scan to make sure you feel well. You will still be able to drive home.

You can eat, drink and go back to your normal activities straight away after your scan. It is advisable to drink plenty of clear fluids over the next 24 hours. This helps your body flush out the dye.

The results will be sent to the doctor who asked for you to have this examination.

As CT scans involve the use of x rays, there is a small risk associated with the radiation dose you will receive.

When your referral form is received by the Imaging Department, a team of Radiographers and Radiologists carefully check the request to see if the benefit of having the scan would outweigh the risk of the dose of radiation you will receive.

Although radiographs or ‘x rays’ have a lower radiation dose associated with them, CT scans provide a more detailed ‘3D’ picture of what is going on inside the body. This can significantly aid your diagnosis or treatment.

If you are required to have an injection for your scan, there is a small risk of having a reaction to the contrast dye. This is a very rare occurrence. When you arrive for your scan, the Radiographers will go through a checklist with you to ensure you are suitable for the contrast dye and minimise this risk. Without the dye, your scan may not be as diagnostic or clinically useful.

If you have concerns about the risk from x rays or the contrast dye, please contact the clinician who referred you for your scan.

If you are unable to tolerate a CT scan, your referring doctor will be informed and he / she can decide if an alternative examination may be more appropriate for you.