Definition and Overview

Calcium CT scan is a diagnostic test performed to assess a person’s risk of developing heart disease such as atherosclerosis and heart attack, to name a few. As an imaging test, it uses a CT scanner to obtain pictures of the heart and the buildup of calcified deposits in the area.

Calcium is one of the most essential minerals in the body and used by the bones to strengthen its structure and support. It is also helpful in maintaining the ideal electrolyte balance so organs can function properly. This mineral, however, is not produced by the body and is therefore obtained from food and products enriched with it such as milk and supplements.

However, not all calcium that goes in can be used by the body and a small percentage remains in the bloodstream. As the blood also contains cholesterol, both have the tendency to create deposits called plaque.

Plaques, a waxy substance, can accumulate in the blood vessels. With calcium, they can harden and can become difficult to remove by natural means. As they accumulate, they can block the passageway of the blood, starving the cells of the nutrients and oxygen they need. The heart will also need to work hard as the blood pressure rises while the arteries can rupture and develop blood clot, a condition known as thrombosis.

The calcium CT scan, also known as coronary calcium scan, is performed to determine the presence of calcium and deposits in the walls of the arteries, which may eventually lead to heart disease. Although it doesn’t prevent the buildup, it can help the doctor delay the progress and assess the patient's risk of developing heart attack, cardiac failure, and arrhythmia.

This type of scan is different from coronary CT angiogram, although both can be used to evaluate the patient’s risk of developing cardiac disease. In CT angiogram, a special dye is often injected into the body to highlight the presence of calcified deposits in the blood vessels.

Who Should Undergo and Expected Results

The American Heart Association discourages persons to use calcium CT scan as a routine test. It is more ideal for people who have a moderate to high risk of developing a heart disease within the next 2 to 10 years. These include people who:

  • Smoke
  • Have an elevated blood cholesterol and blood pressure levels
  • Have fat and sodium-rich diet
  • Have a family history of heart disease
  • Have a sedentary lifestyle
  • Are obese or overweight
  • Have been diagnosed with metabolic syndrome, hypertension, or diabetes

The test may also be recommended when the patient does not seem to have any of these risks but is suffering from symptoms such as chest pain (angina) or irregular heartbeat.

A calcium CT scan is often performed on men and women who are at least 50 years old. Around that time, there’s a huge chance that the body has already accumulated a significant amount of calcium in the arteries, especially if they belong to the at-risk group. A special focus may be given to women who are taking calcium supplements.

The result of the exam is expressed in terms of Agatston score, also called calcium mass score or volume calcium score. Three different points have to be remembered in calculating the score: attenuation value expressed as HU, density factor, and extent of the calcium speck. The density factor is linked to attenuation value that 130-199 HU is equals to 1, 200-299 is equals to 2, 300-399 is equals to 3, and 400 and above is equals to 4.

The extent, meanwhile, is expressed in square millimeters. To know the score, the attenuation value is first determined, and its corresponding density factor is multiplied to the area. Once the product is identified, grading follows.

A score of 0 means there’s no presence of hardened calcium deposits and the risk of developing a heart disease within 2 to 5 years is very low. A score between 1 and 10 is considered minimal while 11 and 100 is mild. It is deemed as moderate if the score is 101 to 400. Higher than 400 is already considered as severe. Those who receive a moderate grading, on the other hand, have around 20% likelihood of developing the disease.

How Does the Procedure Work?

Calcium CT scan, which is typically ordered by a cardiologist, usually does not require any form of preparation. The patient can continue with his or her current diet and even medications. On the day of the procedure, however, it is often advised to wear light or loose clothing and to avoid wearing jewellery pieces and other metals in the body as these can affect the result of the scan.

The test is often conducted in a hospital but in an outpatient setting or in a clinic that has the right CT scanner for the procedure. A technician will be around to operate the machine, which looks like a huge dome with a hollow middle. The central section has a slide that is connected to the table where the patient is going to lie down.

Before the test, electrodes, which are connected to an ECG machine, are attached to the chest area to monitor the activity of the heart. The patient then lies down and enters into the “dome.” The room is equipped with a glass panel so the technician can still see the patient. It is also equipped with speakers that the technician uses to provide instructions to the patient during the test.

A tube with x-ray then goes around the table and takes pictures of the heart. The light beam has the capability to penetrate into the skin and obtain a picture of the heart and the blood vessels. There may be periods when the patient will be asked to hold the breath to obtain a clearer picture. It’s also common to give a medication before the procedure to help slow the heart rate.

It usually takes 10 to 20 minutes for the entire test to be completed. A radiologist interprets the results and forwards it to the cardiologist. In the meantime, the patient can return to normal activities.

Possible Risks and Complications

The test may not be able to detect soft calcified deposits. As for the test itself, the risks are very minimal and the entire procedure is generally safe. Like in most imaging tests, there’s radiation exposure, but it’s extremely low.


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