Carotid high-low flow ratio most accurately predicts significant stenosis
C. J. Meyd, S. Abu-Shakra and M. L. Bleecker
Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Md.
The Doppler quantitative carotid blood flow technique is a dynamic,
physiologic tool that measures carotid blood flow, velocity, and vessel
diameter. A high-low flow ratio that reflects variation in side-to-side
carotid flow is calculated. We determined the accuracy of this method for
the detection of carotid stenosis in 70 patients with cerebrovascular
disease in whom cerebral angiography was the gold standard. The most
sensitive measure proved to be high-low flow ratio, which was abnormal in
19 of 23 patients (82.6% sensitivity). The patients with high-grade
stenosis had contralateral elevated flow compared with that of patients
without high-grade stenosis and age-specific normal subjects. The
quantitative carotid blood flow technique reflects compensatory alterations
in flow produced by significant carotid disease, with an abnormal high-low
flow ratio having the highest positive predictive value. This technique can
be used independently to screen for carotid stenosis and as an adjuvant to
carotid duplex scanning in the investigation of extracranial carotid
disease.