Cardiac Computed Tomography more commonly known as Cardiac CT is a kind of test that utilizes special X-ray machine with hi-fi computers to extract lucid and comprehensive images of the heart. While the scan is being taken, the machine will move over the body of the patient in a circular motion taking images of the different parts of the heart from various angles. The computer attached to the machine will then put all these images together to provide a 3 dimensional image of the heart as a whole.
The cardiac CT is a test that is made use of very commonly by doctors to identify problems related to the heart. Some of the reasons for being asked to take a cardiac CT are given below.
- This scan is used to identify whether there is any build-up of calcium within the walls of the arteries of the heart, which could be an indication that the patient may be suffering from coronary heart disease. Sometimes a contrast dye is injected into one of the veins so that the arteries in the heart can be highlighted in the images making it clearer for the doctor to make a diagnosis.
- The cardiac CT is also used to determine whether the patient has any problems with the functioning of the heart or its valves. This could be recommended instead of an echocardiograph or an MRI in some cases.
- The cardiac CT is also used to detect any problem in the aorta which is the major artery that transports blood to the different parts of the body from the heart.
- Aneurysms or bulging of blood vessels of the heart are also detected using a cardiac CT.
- Clotting of blood in the heart or any trouble with the pulmonary veins can be identified using the cardiac CT.
Preparation for a Cardiac CT Procedure
There is no special preparation that is needed for a cardiac CT. The patient can continue taking his regular medication, but should ensure that he does not take caffeine or smoke for four hours before the test is conducted. All metal objects like jewellery, spectacles, hairpins, dentures etc have to be removed from the body as there are chances that they could affect the images taken. Pregnant women must tell their physicians about their condition before a cardiac CT.
Cardiac CT Equipment
The CT equipment is like a big box that has a big hole more like a tunnel in the centre. The patient will be made to lie on a narrow table that is then slid into the hole or tunnel. Inside the CT scanner there are the x-ray tube and the electronic detectors that are situated at opposite sides inside a ring that is known as the gantry. The computer that processes the images into 3D is located in another room from where the technician operates the equipment and keeps track of the examination.
How Does the Cardiac CT Procedure Work?
This equipment works more or less like an x-ray machine. Many beans from the x-ray machine combined with a series of electronic x-pray detectors revolve round the patient during which process the amount of radiation being absorbed by the body is measured. Simultaneously the table on which the patient is placed passes under the scanner in such a way that the X-ray machine moves in a circular path. The specialized computer application processes the images to create 2D and 3D images that are exhibited on the monitor.
How is the Procedure Performed?
A cardiac CT is usually performed with the technician positioning the patient on the examination table on his back. He may use straps and/or pillows to ensure that the patient maintains the correct position and to ensure that he is steady during the scanning process. Before the table is slid into the scanner, electrodes are attached to the chest and to an ECG machine that keeps track of the electrical activities in the heart. This is what enables the cardiac CT scanning especially when the heart is not contracting too much.
The examination table now passes through the hole into the scanner so as to identify the right position to star the scanning process and the table will then move through the scanning equipment while the actual process is in progress. Sometimes the patient will be asked to hold his breath for about 10 to 15 seconds while images are being taken. Usually the whole process takes between ten to twenty minutes depending on requirements of the physician.
Experience During and After the Process
Typically a cardiac CT is simple, painless and quick. In spite of the fact that there is no pain it does not mean that there may not be some form of discomfort as the patient may have a difficult time trying to lie absolutely still. In addition there are patients who begin to feel claustrophobic when inside the CT scanner. In such cases the doctor may advise giving the patient some sort of medication to help him endure the scanning process.
Inside the CT scanner the patient will be totally alone, though the technician can see, hear and talk to you throughout the scanning process. Inside the scanner there will be special lights and the patient may hear clicking, buzzing and humming sounds as the machine rotates right round the patient.
Once the examination is over, the patient can be as normal as before carrying out his regular activities.
Benefits and Risks of Cardiac CT
The benefits of a cardiac CT are that it a non-invasive and painless means of evaluation for the doctor to determine whether the Patient has any cardiac irregularities. In addition it takes only a few minutes to get the CT done. Further there are not remnants of radiation in the body of the patient once the CT scanning and the x-rays utilized in the cardiac scans do not generally have any after effects.
Regarding risks, there is always a very, very small percentage of chance that the radiation from the x-rays can cause cancer, but it is so minimal that it is rather negligible.
Limitations of Cardiac CT
One of the greatest disadvantages of this scan is that a really huge person may not fit into the scanning machine and the weight limit for the machine is 450 pounds. Moreover cardiac CT scanning is rather expensive and it may not be covered in the insurance plans. Another drawback is that an extremely high heart rate can hinder the quality of the pictures taken, which means that the scan may have to be carried out again another day.