Follow these instructions to ensure a smooth appointment.
Prepare for Your Appointment
In preparing for a CT scan, fluids and food may be restricted for several hours prior to the examination, especially when contrast material is to be used. Contrast material may be injected intravenously, or administered orally to increase the distinction between various organs or areas of the body. All metallic materials and certain clothing around the body are removed because they can interfere with the clarity of the images.
No special preparation is necessary in advance of a cardiac CT examination. You should continue to take your usual medications, but should avoid caffeine and smoking for four hours prior to the exam.
You should wear comfortable, loose-fitting clothing to your exam. You may be given a gown to wear during the procedure.
Metal objects, including jewelry, eyeglasses, dentures and hairpins, may affect the CT images and should be left at home or removed prior to your exam. You may also be asked to remove hearing aids and removable dental work. Women will be asked to remove bras containing metal underwire. You may be asked to remove any piercings, if possible.
You should inform the technologist if you have a pacemaker. Pacemakers do not hinder the use of CT as in MRI as long as the scanner will not be taking images repeatedly over the area of the pacemaker device in the upper chest. This is usually not an issue for cardiac CT exams.
Women should always inform their physician and the CT technologist if there is any possibility that they may be pregnant.
What to Expect
The technologist begins by positioning you on the CT examination table, usually lying flat on your back or less commonly, on your side or on your stomach. Straps and pillows may be used to help you maintain the correct position and to help you remain still during the exam. Depending on the part of the body being scanned, you may be asked to raise your arms over your head.
Electrodes (small, sticky discs) will be attached to your chest and to an electrocardiograph (ECG) machine that records the electrical activity of the heart. This makes it possible to record CT scans when the heart is not actively contracting.
Next, the table will move quickly through the scanner to determine the correct starting position for the scans. Then, the table will move slowly through the machine as the actual CT scanning is performed. Depending on the type of CT scan, the machine may make several passes.
Patients are asked to hold their breath for a period of 10 to 20 seconds while images are recorded.
When the examination is completed, you will be asked to wait until the technologist verifies that the images are of high enough quality for accurate interpretation.
The entire procedure including the actual CT scanning is usually completed within 10 minutes.
A cardiac CT scan for coronary calcium is a non-invasive way of obtaining information about the presence, location and extent of calcified plaque in the coronary arteries—the vessels that supply oxygen-containing blood to the heart muscle. Calcified plaque results when there is a build-up of fat and other substances under the inner layer of the artery. This material can calcify which signals the presence of atherosclerosis, a disease of the vessel wall, also called coronary artery disease (CAD). People with this disease have an increased risk for heart attacks. In addition, over time, progression of plaque buildup (CAD) can narrow the arteries or even close off blood flow to the heart. The result may be chest pain, sometimes called “angina,” or a heart attack.
Because calcium is a marker of CAD, the amount of calcium detected on a cardiac CT scan is a helpful prognostic tool. The findings on cardiac CT are expressed as a calcium score. Another name for this test is coronary artery calcium scoring.
For additional details concerning the above procedures, please visit www.radiologyinfo.org