How Accurate Is Carotid Ultrasound?

Clinicians rely increasingly on noninvasive carotid Doppler ultrasonography to make decisions about invasive carotid procedures. These 2 studies -- one from a veterans hospital and the other from an urban teaching hospital -- examined the accuracy of carotid ultrasound, using angiography as the gold standard.

The first study included 334 vessels in 202 patients. Using peak systolic velocity to determine degree of stenosis, Doppler ultrasound correctly classified 91 percent of stenoses less than 50 percent, 33 percent of stenoses between 50 percent and 69 percent, and 87 percent of stenoses 70 percent or greater. Using the ratio of internal carotid velocity to common carotid velocity, the accuracies for the 3 degrees of stenosis were 89 perce…