Forty-two-year-old Henry is putting on a clown costume, getting ready for his son’s 5th birthday party, and counting his blessings. He knows just how lucky he is to be doing the Bozo thing instead of pushing up daisies. And if it hadn’t been for the EBT scan, pushing up daisies is exactly where Henry would be. “And to think,” he muses, attaching his large red nose, “on the day before I had my convenient and painless [insert brand name here] heart scan that showed I was about to have a massive heart attack, my doctor had given me a clean bill of health. Thanks to [insert brand name here], I was able to get treatment in time.” Then the announcer comes on and says, “And how do you feel? Are you sure? Like Henry here, you could be sitting on a silent time bomb, and your next breath may be your last. So maybe you should schedule an [insert brand name here] EBT, and like Henry, spend your child’s next birthday at Chucky Cheese’s instead of Forest Lawn. Call today.” Then the announcer gives the address and number of – not an obscure office in a failing strip mall – but a highly respected local hospital.
What gives here? Is Electron Beam Tomography (EBT) (also called the Ultrafast CT Scan) some sort of fringe medical procedure, as suggested by the cheesy commercials featuring heart rending vignettes, or is it a legitimate and valuable diagnostic tool, as suggested by its university hospital venue?
As it turns out, the cardiology community has been just as schizophrenic about EBT as have been the commercials. While many cardiologists swear by them, many others consider them a waste of time and money, and a grave risk to the credibility of the profession. In this article, we will examine, as dispassionately as possible, the EBT. We’ll consider whether it is merely another heart test, or whether it really is a uniquely valuable tool that predicts dangerous cardiac events before they occur. And we will try to answer the question: should you have one?
What is EBT?
CT scans have been in wide clinical use for more than 25 years. CT scans arose when standard x-rays met the power of the computer. X-ray images were computer-processed to give pictures of a quality scarcely imagined before the 1970’s. Since their advent, CT scans have become a gold standard for imaging many of the body’s internal organs.But CT scans have never been particularly useful for imaging the heart. This is for one simple reason: the heart moves. Since CT scanners take several minutes to acquire the image, anything that moves during this time becomes blurred. And the coronary arteries, riding as they do on the surface of the heart muscle, are invariably blurred into oblivion.
What's new about EBT is that, through a technique called "gating," this scan is able to make images of the heart, even though the heart is moving. However, even gating the image does not render the coronary arteries visible nearly to the extent of, say, a cardiac catheterization. The EBT does not tell us directly, therefore, whether there are significant blockages in the coronary arteries. What it does tell us, with a high degree of accuracy, is whether the coronary arteries contain deposits of calcium.
Calcium, for all practical purposes, does not occur in normal coronary arteries. Calcium deposits are a strong marker for the presence of atherosclerosis, i.e., coronary artery plaques, the lesions that cause narrowing of the coronary arteries, and ultimately lead to heart attacks. If there is calcium in the coronary arteries, then, you can be pretty sure there is also atherosclerosis. Further testing – usually by means of a cardiac catheterization – might then be indicated to measure the extent of the disease, and to decide on the best way to treat it.
So it all makes perfect sense. Use the EBT as a completely safe, painless, and non-invasive screening test to check for the presence of coronary artery calcification. If it’s present, then you know there’s at least some degree of coronary artery disease, and more invasive procedures can be elected. What could be simpler?
