Identification of High Risk Carotid Artery Stenosis: A Multimodal Vascular and Perfusion Imaging Study

Abstract

Background: Risk stratification of asymptomatic carotid artery stenosis (ACAS) is still an issue for carotid revascularization. We sought to identify factors associated with symptomatic carotid artery stenosis (SCAS) using multimodal imaging techniques. Methods: We retrospectively collected data on patients who underwent carotid artery revascularization. Results from duplex sonography, computerized tomography angiography, brain magnetic resonance imaging (MRI), magnetic resonance angiography (MRA), perfusion-weighted imaging, and demographic profiles were compared between ACAS and SCAS patients. Differences in baseline characteristics between the two groups were balanced by the propensity matching score method. Multivariable regression analysis was performed to identify factors associated with symptomaticity of carotid artery stenosis. We compared the strength of associations between significant imaging factors and symptomatic carotid stenosis using C statistics. Results: A total of 259 patients (asymptomatic 57.1%, symptomatic 42.9%) with carotid stenosis were included. After 1:1 propensity score matching, the multivariable regression analysis revealed that the absence of plaque calcification [Odds ratio 0.41, 95% confidence interval (CI) 0.182-0.870, p = 0.023], deep white matter hyperintensity (DWMH; Odds ratio 3.46, 95% CI 1.842-6.682, p < 0.001), susceptibility vessel sign seen on gradient-echo MRI (Odds ratio 2.35, 95% CI 1.113-5.107, p = 0.027), and increased cerebral blood volume (CBV) seen on perfusion-weighted MRI (CBV; Odds ratio 2.17, 95% CI 1.075-4.454, p = 0.032) were associated with SCAS. The combination of these variables had a fair accuracy to classify SCAS (Area under the curve 0.733, 95% CI 0.662-0.803). Conclusions: We identified several multimodal imaging markers independently associated with SCAS. These markers may provide information to identify ACAS patients with high risk of ischemic stroke. Future studies are needed to predict SCAS using our findings in other independent cohorts.

Keywords: asymptomatic carotid artery stenosis; multimodal imaging; perfusion-weighted MRI; risk factors; symptomatic carotid artery stenosis.

Figure 1

Imaging parameters: MRI, CTA/MRA, PWI, and carotid duplex sonography. MRA shows stenosis of the proximal internal carotid artery (A, white arrow) and contralateral carotid artery stenosis (A, black arrow). In PWI, increased CBV (B) and delayed TTP (C) are shown. FLAIR shows HVS in FLAIR (D) and PWMH/DWMH (F). GRE shows HV in GRE (E). Through duplex carotid sonography, plaque characteristics such as calcification, ulceration, echolucent, and stenosis are shown (G,H).

Figure 2

Receiver operating characteristic (ROC) curve. The accuracy of differentiating SCAS from ACAS was measured using several combination of factors associated SCAS: ROC curve of DWMH alone (blue line), DWMH and absent plaque calcification (orange line), DWMH, absent plaque calcification, and GRE HV sign (green line), and DWMH, absent plaque calcification, GRE HV sign, and increased cerebral blood volume (black line). The combination of all four factors (black line) yielded the best accuracy. AUC indicates area under the ROC curve; CI, confidence interval; p, p-value comparing the two AUCs.