by David Douglas

Last Updated: 2009-07-10 14:50:34 -0400 (Reuters Health)

NEW YORK (Reuters Health) - When non-specific chest pain is being urgently evaluated with whole-chest multi-detector CT, using prospective electrocardiographic (ECG) triggering instead of retrospective ECG gating can reduce the radiation dose by more than 70%, researchers say.

"With the much lower patient radiation dose from using prospective triggering," lead investigator Dr. William P. Shuman told Reuters Health "ECG-gated CT of the whole chest may now be appropriate for a greater proportion of the many patients who come into emergency departments with non-specific chest pain."

In the June issue of the American Journal of Roentgenology, Dr. Shuman and colleagues at the University of Washington School of Medicine in Seattle observe that in retrospective gating, the CT beam is on for 100% of the R-R interval. Prospective triggering is a stop-and-shoot technique which cuts the beam-on time to about 26% of this interval.

To compare radiation doses and image quality with the two approaches, the researchers studied 72 patients undergoing whole-chest CT: 41 with retrospective gating and 31 with prospective triggering.

With retrospective gating, the mean effective radiation dose was 31.8 mSv, compared with 9.2 mSv with prospective triggering. Furthermore, independent reviewers were more than twice as likely to award a high quality score to coronary artery images obtained via prospective triggering.

With wider adoption for chest pain evaluation, concluded Dr. Shuman, "this faster, lower-cost approach to workup using gated CT can then address the growing problems of congestion in emergency rooms and controlling the cost of evaluating this common but difficult problem."

Am J Roentgenol 2009;192:1662-1667.

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