Additional CT slices improve coronary artery resolution, reduce radiation exposure

Radiation exposure has been a dicey issue for researchers developing multislice CT coronary artery imaging. According to critics, MSCT exposes patients to twice as much ionizing radiation as conventional cardiac catheterization.

No one disputes that MSCT produces dazzling coronary artery images, a fact that Dr. H.C. Maximilian Reiser stressed during an opening day press conference at the ECR meeting Friday. The director of the Institute for Clinical Cardiology at the Grosshadern Clinic in Munich described the spectacular coronary artery imaging possible with 64-slice CT technology.

Reiser displayed images acquired with a 64-slice scanner showing coronary artery plaques that were obscured by artifact-causing calcifications on four-slice CT. The axial coronary artery images from the 64-slice scanner characterized the plaque, its calcified cap and lipid core, as well as plaque embedded in the lumen of the artery.

"You can differentiate the patent lumen from the plaque component," he said.

Reiser noted that radiation exposure can be reduced by modulating the amount of exposure through the cardiac cycle, and especially by reducing exposure during systole.

When this and other strategies are employed, the actual radiation exposure associated with 64-slice CT imaging is in the range of cardiac catheterization. The issue is less important with 64-slice CT than with 16-slice scanners and far less than with four-slice technology, where radiation exposure was definitely a reason for concern, he said.