What is Cardiac CT for Calcium Scoring?
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. 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.
What are some common uses of the procedure?
The goal of cardiac CT scan for calcium scoring is to determine if CAD is present and to what extent, even if there are no symptoms. It is a screening study that may be recommended by a physician for patients with risk factors for CAD but no clinical symptoms.
The major risk factors for CAD are:
- high blood cholesterol levels
- family history of heart attacks
- high blood pressure
- cigarette smoking
- overweight or obese
- physical inactivity
How should I prepare?
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 should always inform their physician and the CT technologist if there is any possibility that they are pregnant.
What does the equipment look like?
The CT scanner is typically a large, box like machine with a hole in the center. You will lie on a narrow examination table that slides into and out of this opening.
How does the procedure work?
In many ways CT scanning works very much like other x-ray examinations. X-rays are a form of radiation—like light or radio waves—that can be directed at the body. Different body parts absorb the x-rays in varying degrees.
CT imaging is sometimes compared to looking into a loaf of bread by cutting the loaf into thin slices. When the image slices are reassembled by computer software, the result is a very detailed multidimensional view of the body's interior.
Modern CT scanners are so fast that they can scan through large sections of the body in just a few seconds. Such speed is beneficial for all patients but especially children, the elderly and critically ill.
How is the procedure performed?
The technologist begins by positioning you on the CT examination table, usually lying flat on your back or possibly on your side or on your stomach. Straps and pillows may be used to help you maintain the correct position and to hold still during the exam.
Three 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.
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.
What will I experience during and after the procedure?
This CT exam is painless, fast and easy.
When you enter the CT scanner, special lights may be used to ensure that you are properly positioned. With modern CT scanners, you will hear only slight buzzing, clicking and whirring sounds as the CT scanner revolves around you during the imaging process.
You will be alone in the exam room during the CT scan. However, the technologist will be able to see, hear and speak with you at all times.
After a CT exam, you can return to your normal activities.
Who interprets the results and how do I get them?
Our radiologist interprets the images and will send a signed report to your physician, who will discuss the results with you.
What are the benefits vs. risks?
- Cardiac CT for calcium scoring is a convenient and noninvasive way of evaluating whether you may be at increased risk for a heart attack.
- The exam takes little time, causes no pain, and does not require injection of contrast material.
- No radiation remains in a patient's body after a CT examination.
- X-rays used in CT scans usually have no immediate side effects.
- There is always a slight chance of cancer from excessive exposure to radiation. However, the benefit of an accurate diagnosis far outweighs the risk.
- Women should always inform their physician and x-ray or CT technologist if there is any possibility that they are pregnant.
- CT scanning is, in general, not recommended for pregnant women unless medically necessary because of potential risk to the baby.
What are the limitations of Cardiac CT for Calcium Scoring?
A person who is very large may not fit into the opening of a conventional CT scanner or may be over the weight limit for the moving table which is usually about 450 pounds.
CAD, especially in people below 50 years of age can be present without calcium (non-calcified plaque) and may not be detected by this exam.
Not all health insurance plans cover cardiac CT for calcium scoring.
A high heart rate may interfere with the image quality of the test. If a patient's heart rate is 90 or more beats per minute, the exam may need to be rescheduled.