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CLEVELAND, July 25 -- After a real-world multicenter evaluation with varying levels of expertise, the multidetector computed tomography (MDCT) got a thumb's down as a noninvasive competitor for coronary angiography.

Nearly 30% of the time, 16-row MDCT images of coronary artery segments were of too low quality to be evaluated, said Mario J. Garcia, M.D., of the Cleveland Clinic here. But 38% of patients with non-evaluable MDCT images turned out to have significant obstructive disease.

In addition, MDCT resulted in a high rate of false positives, Dr. Garcia and colleagues reported in the July 26 issue of the Journal of the American Medical Association.

Although single-center studies have reported promising results for MDCT in detecting obstructive coronary disease, few multiple-center studies have been done, the investigators said.

The current study included more than 200 patients referred for non-emergency coronary angiography at 11 centers during 2004 and 2005. Of these patients, 187 were appropriate candidates for MDCT evaluation and underwent imaging. They also underwent conventional angiography, and the results were compared. Analysis of the test results were done at one core laboratory.

Of more than 1,600 coronary artery segments larger than 2 mm in diameter, only 71% were evaluable with MDCT. The performance results for MDCT's ability to detect luminal stenosis of more than 50% in these segments were:

• Sensitivity: 89%
• Specificity: 65%
• Positive predictive value: 13%
• Negative predictive value: 99%

Of the 187 patients, 58 had a false-positive result from MDCT, the study found.

"The results of this study indicate that MDCT coronary angiography performed with 16-row scanners is limited by a high number of non-evaluable cases and a high false-positive rate," the authors said. "Thus, its routine implementation in clinical practice is not justified."

"Nevertheless, given its high sensitivity and negative predictive value, 16-row MDCT may be useful in excluding coronary disease in selected patients in whom a false-positive or inconclusive stress test result is suspected," they added.

"Further studies are needed to determine whether MDCT coronary angiography performed with newer 64-slice scanners provides improved performance characteristics that could justify routine clinical application as a primary diagnostic test," they said.

The study was funded by Philips Medical Systems of Highland Heights, Ohio. Co-author Dr. Hoffman reported receiving honoraria for lectures from Philips Medical Systems and Bracco.

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