ABSTRACT
BACKGROUND AND PURPOSE: The degree of internal carotid stenosis has emerged as the most important predictor of ischemic stroke in extracranial carotid artery disease. The purpose of this study was to assess the validity of the noninvasive techniques for quantifying internal carotid stenosis with respect to the accepted standard of intra-arterial angiography. METHODS: We measured the maximum percentage reduction in luminal diameter on the intra-arterial digital subtraction angiograms of 56 symptomatic patients with extracranial internal carotid stenosis (n = 77) or occlusion (n = 20). These data were compared with independent measurements based on continuous-wave Doppler ultrasonography, pulsed-wave Doppler spectrum analysis, color Doppler-assisted duplex imaging, and magnetic resonance angiography. RESULTS: Correlations with intra-arterial angiography were equally strong (r > .90) for magnetic resonance angiography, continuous-wave Doppler, and color duplex analysis. Positive and negative predictive values for (therapeutically relevant) 70% to 99% stenosis were higher for continuous-wave Doppler (.82, .97) and color duplex (.84, .98) than for magnetic resonance angiography (.79, .81). Also, accuracy in quantifying high-grade stenosis was better for both of these ultrasonographic techniques, mainly due to the frequent occurrence of a "flow gap" on the magnetic resonance angiograms. Continuous-wave Doppler and magnetic resonance angiography, but not color duplex, failed to detect slow residual arterial flow in one and two cases of symptomatic "pseudo-occlusion" of the internal carotid, respectively. CONCLUSIONS: (1) Several noninvasive methods compare well with intra-arterial angiography in identifying and quantifying high-grade internal carotid stenosis; (2) the use of these noninvasive methods may suffice for treatment decisions; and (3) because residual between-method disagreement is partly explained by principles of physics, the validity of continuous-wave Doppler and color duplex in quantifying 60% to 99% stenosis is likely to be underestimated by correlation with intra-arterial angiography.
Subject(s)
Carotid Stenosis/diagnosis , Blood Flow Velocity , Brain/blood supply , Carotid Artery, Internal , Carotid Stenosis/diagnostic imaging , Humans , Ischemia/etiology , Ischemic Attack, Transient/etiology , Prognosis , Prospective Studies , Radiography , Retinal Vessels , Ultrasonography/methodsABSTRACT
UNLABELLED: To assess various non-invasive techniques for quantifying internal carotid artery CA stenosis, per cent luminal diameter reduction on intraarterial angiograms (IAA) was measured in 63 patients with ICA stenosis or occlusion. These data were compared with independent measurements based on MR-angiography, continuous-wave (cw) Doppler ultrasonography, systolic peak flow velocity and colour Doppler assisted duplex imaging. Correlations with IAA were equally strong for MR angiography, cw Doppler and colour Doppler analysis (0.95; 0.92; 0.92). Positive predictive values for > or = 70% ICA stenosis were lower and negative predictive values were higher for cw Doppler (0.85; 0.92) and colour duplex analysis (0.81; 0.94) than for MR angiography (0.86; 0.88). Statistical analysis showed non-linear correlations between percentage of lumen diameter narrowing and the length of the zone of signal intensity loss (0.72) and maximum systolic peak flow velocity (0.77). CONCLUSION: Several non-invasive methods do compare with IAA in identifying and quantifying high-grade ICA stenosis and may suffice for decisions on treatment.