Sensitivity and specificity of transcranial Doppler ultrasonography in the detection of high‐grade carotid stenosis

We evaluated the ability of transcranial Doppler ultrasonography (TCD) of the middle cerebral artery to detect internal carotid artery luminal area stenosis of 70% or greater by comparing TCD with cerebral angiography in 79 subjects, including 22 with normal cerebral arteriograms and 57 with 30% to 100% internal carotid artery stenosis on at least one side. Of six TCD measurements assessed, the flow acceleration provided the greatest sensitivity (82%) and specificity (73%) in distinguishing 70% to 100% carotid stenosis from lesser degrees of stenosis. The overall accuracy of the flow acceleration was 78%, and the positive predictive value was 79%. A flow acceleration of 351.6 cm/sec 2 or less was useful for detecting high-grade stenosis, but there was difficulty in distinguishing unilateral from bilateral high-grade stenosis. TCD measurement of the flow acceleration allows for fairly reliable detection of high-grade stenosis and can thus serve as a useful indirect component of a carotid noninvasive battery.