[ RadSafe ] Experts weigh benefits, high radiation of 'super X-rays'

[Sandy Perle]

Experts weigh benefits, high radiation of 'super X-rays'

A new type of X-ray shows promise as way to confirm heart disease

"64-slice" CT scans might eliminate need for some cardiac 
catheterizations

Medicare, private insurers debating whether to pay for them

Many heart specialists oppose the scans, citing large dose of 
radiation

ORLANDO, Florida (AP) -- A type of "super X-ray" showed promise in 
its first big test as a potentially cheaper, faster and painless way 
to find out whether certain people with signs of heart disease 
actually have it and need treatment.

The scans might eliminate the need for some of the 1.3 million 
cardiac catheterizations done each year in the United States to check 
for clogged arteries, said Dr. Julie Miller of Johns Hopkins 
University.

But the newer scans are controversial. Medicare and private insurers 
are debating whether to pay for them, and many heart specialists 
oppose them, partly because they supply a big dose of radiation.

That raises the risk of cancer and might spur thousands of additional 
cases if the scans were widely used in the population, said Dr. 
Michael Lauer of the National Heart, Lung and Blood Institute.

Speaking at an American Heart Association conference where study 
results of the scan were presented Monday, he called on doctors not 
to use the scans until research proves they save lives.

"I think he went a little overboard" and was reacting to worries the 
scans would be used to screen people with no symptoms, rather than 
the more limited use tested in the study, said Miller, who led the 
research.

This new CT scan technology came on the market two years ago and is 
already used by many hospitals. Because it uses 64 detectors to 
produce and combine images, the scans are called "64-slice CT." The 
images are so detailed that one doctor described them as an almost 
surgical view.

In the new study, the scans were tested against the current gold 
standard method of checking a patient for heart disease: angiograms 
done in a cardiac catheterization lab. A tube is placed in a blood 
vessel in the groin and maneuvered near the heart, and a special dye 
is infused that makes the arteries show up on X-rays.

These can reveal who has blockages and needs treatment with bypass 
surgery or an artery-opening procedure called balloon angioplasty.

The new scans deliver 10 times more radiation to the patient than a 
standard angiogram. Though the technology has been in use, its 
accuracy hasn't been proved.

Miller's international study was the first direct comparison. It was 
funded by scanner maker Toshiba Medical Systems, and Miller has had 
research grants from the company.

Researchers started with 405 people suspected of having heart disease 
and eliminated about one-fourth because they had high amounts of 
calcium in their artery walls. This is common as people age and the 
arteries harden, and doctors worried that such findings could look 
like blockages and bias results.

The remaining 291 people were given the new CT scans, then standard 
angiograms.

Nine out of 10 patients with blockages were identified by the scans, 
as were 83 percent of those without blockages. The scans ruled out 
heart disease in half of the patients -- people who could have been 
spared the pain, expense and risk of catheterization, Miller said.

The ability of the painless scans to rule out problems is "exciting," 
but questions remain about how they would do on a fuller range of 
patients, said Dr. Timothy Gardner, a Delaware cardiologist and heart 
association spokesman.

The association recently sent Medicare officials a letter opposing 
the scans for screening people with no heart disease symptoms, but 
saying they could be considered for those with symptoms or to check 
for heart defects, said Dr. Raymond Gibbons of the Mayo Clinic, a 
former heart association president.

Others said the study did not change their opposition to the new 
technology.

"I don't buy it," said Dr. Steven Nissen of the Cleveland Clinic, 
former president of the American College of Cardiology. "If you do a 
CT and you find anything, you've got to do a catheterization anyway."

Researchers also "cherry-picked" the kind of patients most likely to 
have heart disease to test in the study.

"It's not for the walking well" who worry they might have hidden 
problems, said Dr. W. Douglas Weaver, a Detroit, Michigan, heart 
specialist and president-elect of the College of Cardiology.

The new scans cost under $1,000; angiograms from catheterization cost 
$2,500 or more. Advanced scanners offering 128- and even 256-slice 
images are coming into use, so the issue will grow as images become 
more detailed.

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The debate involves a turf war between cardiologists who do the 
current angiograms versus radiologists who do the new scans.

Also at the heart conference Monday:

o New research has doctors excited again that experimental drugs that 
boost good cholesterol can help cut the risk of heart attack.

New details on why Pfizer's failed drug torcetrapib raised the risk 
of death showed that its problems were unique and don't appear to 
apply to other medications being tested by Merck & Co. and Swiss drug 
maker Roche Holding AG. (Pfizer Inc. abandoned its $800 million 
investment in torcetrapib last December.)

"It looked very gloomy for this method of raising HDL. I am not 
gloomy for the prospects for this class anymore," said Nissen, who 
headed one of the stopped Pfizer experiments.

o Crestor, a statin drug that lowers bad cholesterol, did not cut the 
risk of death among elderly heart failure patients but helped some 
avoid hospitalization, according to a study sponsored by Crestor's 
maker, AstraZeneca PLC.

Statins are mostly prescribed to prevent heart attacks in people with 
clogged arteries. They are not typically prescribed to people who 
suffer from heart failure, which occurs when a weakened heart can no 
longer effectively pump blood.
-----------------------------------------
Sander C. Perle
President
Global Dosimetry Solutions, Inc.
2652 McGaw Avenue
Irvine, CA 92614 

Tel: (949) 296-2306 / (888) 437-1714  Extension 2306
Fax:(949) 296-1144

E-Mail: sperle at dosimetry.com
E-Mail: sandyfl at cox.net 

Global Dosimetry Website: http://www.dosimetry.com/