The high resolution cardiac CT images allow the detection of minute amounts of calcium in the coronary arteries. Calcium is the sclerosis part of atherosclerosis. It's the part that causes hardening of the arteries. Calcium in the coronary arteries is virtually only seen in the presence of coronary artery disease. The extent of the calcification is a reflection of the extent of plaque deposition in the arteries.
Coronary calcification occurs before there is a significant blockage of a vessel.
So, this technique can define the presence of coronary artery disease years before it would be detectable by stress testing. The patients at risk who are candidates for EBCT are men between 35 and 55 years of age and women between 40 and 60 years of age who have one or more of the coronary risk factors. Patients can self refer for EBCT testing similar to the way a woman can self refer for a mammography. With the other forms of testing that we described, the referral is made through a physician. Any physician could refer for the testing.