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Understanding the Technology prior to the Dual-Source CT Scanner - The 64-slice CT Coronary Angiogram |
The following is an article written about the latest scanning technology a few years back. This will help you better understand the improvements in scan equipment.
With new 64-slice CT scanners there everywhere these days, be sure to get your heart scan with it.
The new scanners do provide really good images of the coronary arteries. But, say you have a 20% blockage in an artery by a coronary angiogram generated on one of these devices. What will you do in 1, 2, or 3 years when you want to find out if you have progressed? Should you have the CT angiogram done again?
If you did you'll be exposed to a huge dose of radiation--appropriate for a diagnostic test, but not for a screening test. The radiation exposure is similar to undergoing a full conventional cardiac catheterization, or up to 100 chest x-rays.
"20% blockage" is also just an estimate of the diameter reduction at one spot. That number reveals nothing about the lengthwise extent of plaque or about the potential for "remodeling", that is the phenomenon of artery enlargement that takes place as plaque grows. So if you had another CT coronary angiogram a year later and was told that your blockage was still 20%, actually you could have had considerable plaque growth but it would not be shown in that value.
People will come to me after getting a CT angiogram for a suggestion. I have to send them back to their scan center to get a simple coronary calcium score. That measure is easy, quantitative, precise, and can be repeated annually to note the progression. Some physicians ridicule the heart scan, or calcium, score--it's old, boring, only a measure of hard plaque. But that is not true at all. The coronary calcium score is a measure of total plaque (hard and soft). And when you know how to control and reduce your score, then it's the most exciting number in your entire health program!
So if you go to a scan center and they direct you to a 64-slice CT scanner, or if your doctor orders one, you should insist on getting a calcium score out of the test. Centers that refuse to generate a score certainly have one thing on their mind: identifying people with severe blockages sufficient to obtain the downstream financial bonanza--angioplasty, stents, and bypass surgery.
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