In asymptomatic adults aged 65 years or older, that risk of incident stroke was associated with two US features: hypoechoic internal carotid arterial plaque and an estimated internal carotid arterial stenosis of 50%-100%.

Doppler and real-time ultrasound (US) were performed to evaluate the extent of atherosclerotic changes in the carotid artery and to assess their relationship to prevalent cerebrovascular disease. Real-time US scans and Doppler measurements of the carotid arteries were analyzed in 5,201 subjects aged 65 years or older. Severity of atherosclerotic lesions was associated with increased frequencies of hyperechoic, irregular, and heterogeneous textured lesions (P < .0001). The severity of internal carotid artery stenosis was associated with thickening of the intima-media layer of the common carotid artery wall (r = .37, P < .0001). A history of stroke and transient ischemic attack (TIA) was more likely when hyperechoic, heterogeneous, and irregular lesions were seen in the carotid artery. Internal carotid artery stenosis correlated better with prevalent stroke and TIA than did sonographic descriptions of plaque texture. However, the prevalence of hyperechoic, heterogeneous, and irregular lesions increased as the degree of internal carotid stenosis increased. On real-time images alone, the average of the internal carotid artery maximal wall thickness is the sonographic measure of atherosclerosis that enables the best prediction of prevalent stroke and TIA.

The accuracy, rapidity, and reproducibility of color-Doppler-assisted duplex sonography in the diagnosis of significant internal carotid artery stenosis were prospectively evaluated. Only the point of maximal color shift on the color map was used for spectral analysis. When compared with angiography in 60 carotid bifurcations, a measured peak systolic velocity above 1.25 m/sec was 87% accurate in the detection of significant internal carotid artery stenoses greater than 50%. Determination of maximal internal carotid artery velocity was 40% faster with color-Doppler-assisted duplex sonography than with nonassisted duplex ultrasound. The correlation coefficient for interobserver agreement was .90. It increased to .97 when cases of extensive (greater than 1 cm) acoustic shadowing (7% of bifurcations) were excluded. The authors conclude that the color flow map is an accurate and reproducible means of depicting the point of maximal stenosis within the internal carotid artery.

Findings of two-dimensional time-of-flight magnetic resonance (MR) angiography projection angiograms were prospectively compared with those of color Doppler sonography by using angiography as a standard in 23 consecutive patients (42 carotid bifurcations) to evaluate their utility in determining the presence of carotid artery stenosis. MR angiography helped detect 50% or greater lumen diameter stenosis (sensitivity, 0.96; specificity, 0.64). Color Doppler sonography with 1.25 m/sec peak systolic velocity as a threshold had a sensitivity of 0.96 and a specificity of 0.71. Statistical analysis showed a correlation between percentage of lumen diameter narrowing and the length of the zone of signal intensity loss with MR angiography (r = .69; P less than .0001). A stronger relationship was obtained between angiographic narrowing and peak systolic velocity derived from color Doppler sonography (r = .80; P less than .0001). Two-dimensional time-of-flight MR angiography displayed as projection angiograms and combined with carotid artery and combined with carotid artery sonography is a useful approach for helping detect and potentially grade the severity of stenoses of the carotid artery.

Between 1978 and1988, the diagnosis of atheromatous pseudo-occlusion of the internal carotid artery was made in 34 patients by angiography. Results of noninvasive tests were abnormal in 33 of the 34 patients examined. Twenty-five patients had carotid endarterectomy, and the other nine were treated medically. Four of the 34 patients (12%) had significant complications, two related to angiography and two to surgery. Twenty-three of the 25 operated patients were seen in long-term follow-up; 19 (83%) were found to have a patent operated vessel by noninvasive testing. None of the 23 operated patients followed up suffered recurrent neurologic deficits following surgery; two had distant contralateral strokes. Three of the nine patients treated medically (33%) experienced delayed ipsilateral stroke. This study shows that the risks associated with angiography and surgery for atheromatous pseudo-occlusion are significant and are higher than previously reported. (Stroke 1989;20:1168-1173 H ighly stenotic but patent internal carotid arteries (ICAs) can easily be misdiagnosed as occluded by both noninvasive testing and by angiography. Blood flow distal to a site of extreme stenosis may be so minimal that it remains undetected. The term "atheromatous pseudo-occlusion" was first used by Lippman et al in 1970.] They described layering of contrast material along the dependent posterior wall of the ICA distal to a site of high-grade stenosis at the time of angiography. Other descriptive terms used to categorize the angiographic appearance of such extremely stenotic lesions are the poststenotic slim sign, the string sign, and the nearly occluded carotid artery.2 -8 Once identified, urgent carotid endarterectomy seems to be automatically accepted as appropriate for pseudo-occlusion. However, surgery for pseudo-occlusion should be attempted only if surgically treated patients are shown to have better prognoses than those treated medically and if longterm patency of the operated vessel is high. These issues have not been previously addressed.This report describes our experience with 34 patients with atheromatous pseudo-occlusion. All 34 underwent selective carotid angiography, and 25 subsequently had carotid endarterectomy. We report on the complications associated with both procedures. We also report the long-term clinical out-