Duplex ultrasound scanning of the carotid arteries with velocity spectrum analysis.

Abstract

Duplex ultrasound examination of the carotid arteries using high-resolution realtime imaging and pulsed Doppler flow measurements with velocity spectrum analysis was performed on a series of 50 consecutive patients (100 vessels), and findings were compared with findings of conventional carotid arteriography. The criteria for an abnormal duplex examination included: a velocity ratio of 1.5 or more (ratio of the maximum internal carotid artery [ICA] flow velocity to the maximum common carotid artery flow velocity); turbulence, as indicated by an ICA velocity spectral width of 40 cm per second or more; visible plaque that produced an ICA stenosis of 50% or more; a maximum ICA velocity of 100 cm per second or more; and inability to detect ICA flow. A flow-limiting stenosis was defined arteriographically as a 50% or greater stenosis of the diameter of the arterial lumen. The velocity ratio was the best single duplex criterion, with an overall accuracy of 88%. The sensitivity or specificity of the duplex examination was as high as 97%, depending on the number of duplex criteria that were abnormal.

Duplex carotid sonography. Peak systolic velocity in quantifying internal carotid artery stenosis.

“…extensive ICA plaque; 2 elevated diastolic velocity (>100 cmjsec); An additional useful criterion, not addressed in this study, is the use of ratios of peak systolic velocity in the ICA to peak systolic velocity in the CCA. 3 .s,u Elevated ratios may be useful in identifying stenosis in patients with decreased myocardial contractility and consequent reduced velocity throughout the carotid system. Duplex sonography is a valuable screening method for carotid artery disease.…”

“…Garth et al propose five criteria for a flowlimiting stenosis (SO% or greater diameter reduction): a ratio of the maximum ICA flow velocity to the maximum CCA flow velocity of 15 or more; turbulence, as indicated by an ICA velocity spectral width of 40 cmfsec or more; visible plaque that produces an ICA stenosis of SO% or more; a maximum ICA velocity of 100 cmfsec or more; and an inability to detect ICA flow. 3 In the study by Vaisman and Wojciechowski, two additional criteria in the prediction of significant disease (greater then 50% diameter reduction) are proposed: peak systolic average velocity in the CCA of less than 25 cmfsec and the ratio of right to left peak systolic average velocities in the CCA of less than 0.7 or greater than 13. 4 In a recent study, Robinson et al distinguished four categories of ICA cross·sectional area (rather than diameter) stenosis: < 70%, 70% to 89o/o, 90% to 99%, and occlusion.…”

Color-flow Doppler and conventional duplex scanning of the carotid bifurcation: prospective, double-blind, correlative study

“…To differentiate the most severe degree of stenosis, we used an enddiastolic peak velocity of 1 00 cm/sec (Figs. 1-3) [7,8].…”

Carotid plaque morphology and risk for stroke.

“…25 Carotid duplex ultrasound is complementary to angiography. 26 This technique provides information which adds another dimension to carotid plaque examination. Current instrumentation allows histologic characterization and classification of the plaque, 27 -28 including the identification of ulcers and intraplaque hemorrhages.…”

“…29 - 30 The effect of plaques on flow (degree of turbulence) also assists in the determination of the degree of stenosis. 26 The main limitation of carotid duplex ultrasound is its inability to differentiate between complete and subtotal occlusion, a so-called "string sign." However, newer instruments which use color flow Doppler imaging promise to overcome this limitation.…”