What is a coronary calcium scan?

Because atherosclerotic plaques almost always contain calcium deposits, they can be visualized by x-ray. In the last several years, specialized, high speed, CAT scanners have been developed that rapidly scan the heart "between" heartbeats and identify the presence of calcium in the coronary arteries. The resolution of these scanners is not quite sharp enough to detect the degree of narrowing of the coronary artery channel. However, the images are able to provide information about the quantity of calcium in the heart and calculate a "calcium score." Because the amount of calcium in the heart correlates with the amount of cholesterol plaque, a conclusion can be drawn regarding how much plaque one has in his/her coronaries. This gives an idea of the likelihood of a future cardiac event, such as a heart attack.

Thus, a calcium scan cannot identify a specific lesion, or narrowing in a coronary artery that may lead to symptoms or to a heart attack, but it can identify which patient may be at risk. A calcium scan is not appropriate for everyone, particularly if someone has already had coronary angiography. Physicians sometimes use a calcium scan if a patient has undergone a stress test which has shown equivocal results.