Opinion varied on CT scan detecting blocked arteries

San Francisco, November 27: Clogged arteries, to some extent, can be detected through 64-slice images generated by high-end CTdefine scan machines.

The latest study report claimed that CTdefine scan can be quite successful in detecting clogged arteries but the "multidetector CT angiography cannot replace conventional coronary angiography at present."

Researchers studied 291 people with suspected coronary arterydefine blockages across nine hospitals in the U.S, where the patients were subjected to 64-CT and conventional coronary angiography. 84 percent of the cases were detected precisely by CT scanning while angiography detected 82 percent.

But the study compelled researchers to raise questions over compensation made by Medicare towards these high-priced CT scanning. Dr. Rita F. Redberg, who co-authored an editorial in the journal, said: "There is no evidence that they are of benefit to patients. In general, there should be evidence of benefit before there is widespread use." Dr. Rita is the professor of medicine at University of California in San Francisco.

However, Dr. Julie M. Miller, an assistant professor of medicine at Johns Hopkins University and lead author of the study, said that these scans can be employed as a part of cardiovascular treatment.

"Our study shows they do have value, because they have a high degree of diagnostic accuracy to identify patients with tight heart blockages. Having the scan is a noninvasive procedure, and that is very attractive. Patients do not undergo the risk, even though it is small, of angiography," said Miller.

Conventionally, artery blockage is measured by angiography, where a thin catheterdefine tube is inserted in the blood vessels to determine the extent of obstruction.

Miller quoted "Our paper shows for the first time that 64-CT scans can identify patients who need to go on to angioplasty and bypass procedures. It has diagnostic accuracy compared to other tests, such as stress testing. They create more invasive catheterizations than are needed than if the 64-CT test is used."

Miller explained that "Until now, there has been doubt about 16-row or 64-row CT scanners being able to diagnose coronary disease. The new study dispels that doubt."

On the contrary, Dr. Redberg stated "We need to have a study that uses CT and the traditional strategy and look at the outcome in the two arms to see which is better."

While Miller is certain that CT scans can effectively diagnose artery blockage, editorial authored by Redberg argues the heavy expenses involved in scans and also the invariable radiations patients may get exposed to during the scan. About 2 percent of overall U.S. cancerdefine cases occur due to CT radiationdefine exposure, another study shows.

Earlier, the national Medicare program had refused to cover CT scan expenses, citing a reason that "evidence is inadequate" in verifying their significance, says the editorial.

According to the editorial, "the use of cardiacdefine imaging has been increasing by 26 percent per year, despite a lack of evidence of outcome benefit. Without such evidence, a high-resolution CT angiographic CT image of the heart is just another pretty picture."

"The cost to patients is generally reasonable when compared to other noninvasive imaging tests and cheaper than catheterization in general," said Miller. Cardiac CT scans may be helpful "for someone complaining of angina [chest pain] who needs further noninvasive evaluation, instead of a stress test, or patients who have had a previous stress test where the results were not clear."

The study is published in the issue dated November 27 of the 'New England Journal of Medicine'.