Noninvasive ultrasonic carotid angiography: prospective validation by contrast arteriography

Pulsed ultrasonic images of the carotid bifurcation in 82 vessels of 43 patients were compared independently with contrast arteriograms for stenosis (by percentage quartiles) or occlusion of the internal carotid artery. All 14 occluded vessels were identified correctly by ultrasound but were visualized on repeat examination. Estimation of percentage stenosis on ultrasonic images agreed with the quartile determination by contrast arteriography in 35 of 68 (51 percent) vessels and was within one quartile of correct interpretation in 48 of 68 (71 percent). The interpretative error of grading stenosis of ultrasonic images was due to vascular wall calcification which inhibited ultrasound transmission. This limitation was overcome by sound spectral (sonographic) analysis of distal internal carotid flow velocity which allowed estimation of stenosis within one quartile of that determined by contrast arteriography in 46 of 47 (98 percent) vessels.