Coronary computed tomography angiography (CCTA) combines a CT scan and an iodine-based contrast medium to examine the arteries that supply blood to the heart. The images that are generated during the scan can be constructed to create a three-dimensional image which may be viewed on a monitor, or printed on film.
CCTA is a non-invasive method to evaluate the blood vessels of the heart. The patient is connected to a cardiac monitor which shows the heart’s electrical activity and an intravenous line is placed into an arm vein. During this scan, x-rays pass through the body and are picked up by special detectors in the scanner. A high number of detectors results in clear, conclusive images. For that reason, CCTA’s are often referred to as multi-detector, or multi-slice, CT scanning. When the contrast medium is introduced to the bloodstream during the procedure, it allows for clear definition of the blood vessels that are under examination by making them appear bright white. A beta blocker may also be administered to the patient through the same IV line, or given orally to help slow down the heart rate, to aid in improving image quality.
Nitroglycerin may also be administered as a tablet, or a spray underneath the patient’s tongue, to dilate and improve visualisation of the coronary arteries.
The CT scanner is typically a large box-like machine with a tunnel through the centre. The x-ray tube and detectors are located opposite one another in a ring, called a gantry, and they rotate around the patient. CCTA works on the same principle as a standard CT scan, the only difference being the speed. The scanned images will appear on a computer screen, and the radiologist will use these images to create three-dimensional images and images in various planes to completely evaluate the heart and coronary arteries.
CCTA is indicated for patients with suspected abnormal anatomy of the coronary arteries, i.e. plaques or atherosclerosis.
Unlike conventional x-rays, CT scanning provides very detailed images of many types of tissue. The examination is fast and simple, as well as non-invasive.