Ultrasound densitometric analysis of carotid plaque composition. Pathoanatomic correlation.

BACKGROUND AND PURPOSE

The components of a carotid artery plaque might affect the risk of ipsilateral stroke. The accuracy of carotid duplex scan in assessing stroke risk reflects the experience of the scan reader. Thus, methods that can enhance ultrasonic evaluation of plaque morphology might allow a more objective means of determining carotid-mediated stroke risk.

METHODS

We performed densitometric analysis of B-mode images of carotid plaques in nine patients scheduled for carotid endarterectomy. All patients had preoperative duplex color imaging and cerebral arteriography. The surgical specimen was analyzed histologically to determine the plaque components (soft plaque/organized thrombus, intraplaque hemorrhage/lipid deposition, fibrosis, and calcification). The specimen findings were correlated with the densitometric measurements to determine whether the density analysis would allow a reliable determination of the plaque substratum.

RESULTS

With 1.0 as a reference point for the moving column of blood, the mean acoustic densities (+/-SD) were as follows: organized thrombus, 1.8 +/- 0.5; intraplaque hemorrhage/lipid deposition, 5.15 +/- 0.9; fibrosis, 9.51 +/- 2.9; and calcification, 15.5 +/- 8.6.

CONCLUSIONS

We conclude that densitometric evaluation allows differentiation of the various possible components of carotid plaque. The determination of plaque composition, based on density measurement, may provide information about its potential for thromboembolization.