Cardiacare

PROGRAM HIGHLIGHTS

• Computed Tomography (CT) Coronary Arteries

PROGRAM DETAILS

What is Cardiac CT for Calcium Scoring?

Cardiac CT for calcium scoring is a non-invasive way of obtaining information about the location and extent of calcified plaque in the coronary arteries – the vessels that supply oxygen-containing blood to the heart wall. Plaque is a build-up of fat and other substances, including calcium, which in time can narrow the arteries or even close off blood flow to the heart. The result may be painful angina in the chest or a heart attack. Calcium is a marker of coronary artery disease. The findings on cardiac CT, expressed as a calcium score, may help decide what measures can be taken to avoid these events. Another name for this test is coronary artery calcium scoring.

What are some common uses of the procedure?

The goal of cardiac CT for calcium scoring is to detect coronary artery disease (CAD) at an early stage when there are no symptoms and to determine its severity. It is a screening study that may be recommended by a physician if you have risk factors for CAD but no clinical symptoms yet. The procedure is most often suggested for men aged 4o years or older and for women who are aged 45 and above or are postmenopausal. Some patients choose to have the test on their own even if their doctors have not recommended it, in order to discover early-stage CAD if present, or reassure themselves that they probably do not have advanced CAD.

The major risk factors for CAD, other than age, are: How should I prepare for the procedure?

No special preparation is necessary in advance of a cardiac computed tomography (CT) examination. You may continue to take your usual medications, but should avoid caffeine and smoking for four hours before the exam. At the time of the exam you will be asked to disrobe above the waist, put on a gown, and remove any jewelry that could interfere with the CT scan. If your heart rate is 90 beats a minute or higher, you may be given a drug to slow the rate in order to obtain accurate CT images.

How does the procedure work?

During a computed tomography (CT) scan, the rotating gantry will emit x-rays that pass through the part of the body being examined – in this case the heart and coronary arteries. In spiral or helical CT, the patient passes through the scanner as the gantry rotates. Multiple detectors mounted on the gantry along with the x-ray tube record the radiation leaving the body. The result is that the x-ray beam follows a spiral path. The recorded images are reconstructed by computer using a special software program. Recently developed spiral CT scanners produce high-quality images in less than 10 seconds. This is especially important for elderly patients and those who cannot hold their breath for the required time.

A negative cardiac CT scan that shows no calcification within the coronary arteries suggests that atherosclerotic plaque is minimal at most, and that the chance of coronary artery disease developing over the next two to five years is very low. A positive test means that coronary artery disease is present even if you have no symptoms. The amount of calcification – expressed as a score – may help to predict the likelihood of a myocardial infarction (heart attack) in the coming years.

How is the procedure performed?

During cardiac computed tomography (CT) for calcium scoring, you will lie on your back on the table attached to the CT scanner. The table slides through the opening in the scanner while, at the same time, a cylinder around the opening rotates around your body. The table will move forward slightly every few seconds so that you will be in the proper position for each new cross-section. This process continues until the region of the heart has been thoroughly covered. You will be asked to hold your breath for periods of 20 to 30 seconds while images are recorded.

What will I experience during the procedure?

Cardiac computed tomography for calcium scoring is a relatively simple procedure that takes only about five to 10 minutes. You will be alone during the scan, but the radiologic technologist who performs the exam can see and hear you from the nearby control room and can speak to you at any time. If you become anxious when in confined spaces, you may have to take medication to stay relaxed. This does not happen often because the cylinder within the scanner does not enclose your entire body and your head remains outside the unit.

Who interprets the results and how do I get them?

A radiologist, a physician experienced in CT and other radiology examinations, will analyze the images and provide a report to your primary care or referring physician.

What are the benefits vs. risks?
Benefits

• Cardiac computed tomography (CT) for calcium scoring is a convenient and noninvasive way of evaluating the coronary arteries.
• The calcium score gives an idea of whether coronary artery disease (CAD) is present despite a lack of symptoms, or is likely to develop in the next few years.
• Cardiac CT takes little time and causes no pain.
• The exam does not require injection of contrast material and therefore avoids its possible side effects.
• The examination can suggest the presence of CAD even when the coronary arteries are less than 50 percent narrowed. Standard cardiac tests will not reliably detect this level of blockage, and more than half of all heart attacks occur with less than 50 percent narrowing.

Risk

• The exam exposes the patient to a limited amount of radiation. The dose is similar to that from 10 chest x-rays and about 10-20 percent of that received during a diagnostic cardiac catheterization procedure.
• Women should always inform their doctor, x-ray technologist or nurse if there is any possibility that they are pregnant.

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