Cooperation in coronary CTA may wipe out EBCT

While the recent creation of the Society for Cardiovascular Computed Tomography may give birth to a new era of cooperation between radiologists and cardiologists, it might also sound the death knell for electron-beam CT.

The Society for Cardiovascular Computed Tomography was born out of the merger in March of the American Society for Cardiac Computed Tomography and the Society for Cardiac Computed Tomography. The two fledgling organizations were roughly divided along academic and private practice lines. Members of the Society for Cardiac Computed Tomography were more closely associated with EBCT and the Society of Atherosclerosis Imaging. The other group primarily comprised hardcore multislice CT angiography practitioners. With the fusion of the two groups, the EBCT proponents will be overwhelmed, according to cardiologist Dr. Carter Newton, CT imaging consultant to South Carolina Heart Center in Columbia.

"The EBCT guys are all uniting behind the faster gantries," he said.

Zahi A. Fayad, Ph.D., president of the SAI, said the society supports the use of any modality to detect atherosclerosis. Practitioners will use EBCT as long as industry supports the scanners. GE Healthcare continues to sell, manufacture, and develop the eSpeed system, its current EBCT product. But some market analysts say that GE's promotional push has slowed to a virtual halt. Even practitioners highly invested in EBCT are skeptical.

"We're struggling to survive in an atmosphere where our biggest competitor is the owner of the company: GE," said Dr. James Ehrlich, medical director of Colorado Heart and Body Imaging.

Ehrlich and a few dozen EBCT practitioners met with GE representatives in June to discuss support for the technology. The vendor suggested the group "upgrade" their EBCT scanners with 64-slice MSCT.

"We don't regard that as an upgrade, and we told them that," Ehrlich said.

As of June, GE had sold more than 500 64-slice scanners. Since it bought the electron-beam technology in 2001, the company has sold about a dozen scanners.

"There's no question the market is demanding a more versatile heart scanner," said Charles Wickens, cardiology CT marketing manager for GE.

EBCT proponents are also working against themselves. A press release touting the St. Francis heart study, which found EBCT-measured coronary calcium score to be a better predictor of cardiac events than conventional risk factors, used the term "EBCT" only twice. The preferred term was "fast CT scanning." The PR team made a conscious decision to avoid the unfamiliar "electron beam CT" so the release would have the greatest impact among MSCT users, said lead author Dr. Alan Guerci, president and CEO of St. Francis Hospital.

The hospital has since scrapped its old 150 electron-beam scanner and replaced it with a Siemens 64-slice machine to gear up to performing cardiac CT angiography. A review of the literature convinced Guerci that MSCT can accurately measure coronary calcium, and no material difference in interscan variability exists. In addition, the EBCT scanner delivered an absorbed dose of 1 mSv for calcium scoring, compared with 2.5 mSv for the 64-slice machine.

"Even if there is a measurable risk, it pales in comparison to the risk of not identifying those who need treatment or to the financial burden of unnecessarily taking statins for years," Guerci said.

EBCT proponents point out that most of the literature validating coronary calcium scoring comes from EBCT studies, and MSCT users do not mention that fact to patients. Unlike EBCT, MSCT cardiac patients need beta blockers, although that may change with the 64-slice generation. There is no literature supporting the view that CT scanners can track progression of disease, and the radiation dose from a cardiac MSCT scan is 10 times greater than from an EBCT machine.

"The loss of EBCT will be a loss of a well-validated technology with a radiation dose that will be unparalleled in the foreseeable future with MSCT," said Dr. Matthew Budoff, vice president of SAI and an associate professor of medicine at the University of California, Los Angeles.

But the trade-off for the lower dose is less diagnostic information, said Dr. U. Joseph Schoepf, director of CT research and development at the Medical University of South Carolina in Charleston.

"I'd rather have a test that uses more radiation and provides more accurate results in the proper setting than relying on a test that uses less radiation and provides less diagnostic data," Schoepf said.

EBCT users will be vocal because they have to maintain credibility for having bought that type of equipment, he said. Schoepf gives the existing EBCT scanners five years, at most, before they become too expensive to maintain.