Ultrasound-based carotid plaque characteristics combined with dynamic cerebral autoregulation: An imaging biomarker for cerebral ischemic events in patients with severe carotid artery stenosis

Background

Atherosclerotic stenosis of the carotid artery is a major cause of ischemic stroke. We aimed to identify extracranial and intracranial features associated with cerebral ischemic events in patients with severe carotid artery stenosis using carotid ultrasonography and transcranial Doppler.

Methods

We retrospectively enrolled 130 patients with severe carotid artery stenosis and 45 age- and sex-matched healthy controls. Extracranial carotid artery parameters included carotid plaque morphology, echogenicity, and the gray-scale median (GSM). Intracranial features, mainly dynamic cerebral autoregulation (dCA), were assessed using transfer function analysis. Correlations between extracranial and intracranial parameters and cerebral ischemic events were analyzed using univariate and multivariate logistic regression analyses. Receiver operating characteristic (ROC) curves were compared.

Results

Sixty-six patients (50.8 %) experienced cerebral ischemic events upon admission. Extracranial features (proportion of ulcerated plaques and echogenicity classification) significantly differed between the asymptomatic and symptomatic groups. The mean GSM of carotid plaques (48.9 ± 17.3 vs. 62.1 ± 18.3, P < 0.001) and intracranial parameters were significantly lower in the symptomatic group. Plaque ulceration, hypoechoic plaques, and impaired dCA [lower ipsilateral phase at very-low frequency (VLF)] were independently associated with cerebral ischemic events in patients with severe carotid artery stenosis. The combined GSM and ipsilateral phase at VLF had the highest area under the ROC curve (0.784).

Conclusions

Combined extracranial and intracranial assessments may help predict cerebral ischemic events in patients with severe carotid artery stenosis. Ultrasound-based carotid plaque characteristics, combined with dynamic cerebral autoregulation, could be imaging biomarkers of cerebral ischemic events in patients with severe carotid artery stenosis.