Assessment of nonstenotic coronary lesions by 64-slice multidetector computed tomography in comparison to intravascular ultrasound: evaluation of nonculprit coronary lesions.

BACKGROUND

Multidetector computed tomography (MDCT) has recently emerged as a potential noninvasive alternative for high-resolution imaging of coronary arteries.

OBJECTIVE

In this study, we evaluated 64-slice MDCT for detection, quantification, and characterization of atherosclerotic plaque burden in nonculprit lesions.

METHODS

Data from 11 patients who underwent both MDCT and intravascular ultrasound (IVUS) for suspected coronary artery disease were collected, and a total of 17 coronary segments and 122 cross-sectional slices were analyzed by MDCT and IVUS. Coronary segments on MDCT were coregistered to IVUS, and each obtained slice was scored by 2 blinded observers for presence and type of plaque. Quantitative measurements included cross-sectional vessel area, lumen area, wall area, plaque volume, and plaque burden. Mean and standard deviation of Hounsfield units (HUs) were recorded for plaque when present.

RESULTS

Overall sensitivity for plaque detection was 95.0%, and specificity, positive predictive value, negative predictive value were 88.7%, 89.1%, and 94.8%, respectively. Spearman's correlation coefficients were 0.85, 0.75, 0.70, 0.89, and 0.54 for cross-sectional vessel area, lumen area, wall area, plaque volume, and plaque burden, respectively. The interobserver variability for plaque burden and plaque volume measurements between readers on 64-MDCT was high at 32.7% and 30.4%, respectively. Combined noncalcified plaque had a mean MDCT density significantly different from that of calcified plaque. Soft and fibrous plaques were not able to be distinguished based on their HU values.

CONCLUSION

Sixty-four-slice MDCT had good correlation with IVUS but with high interobserver variability. Plaque characterization remains a challenge with present MDCT technology.