Associations Between Carotid Plaque Characteristics and Perioperative Cerebral Blood Flow Determined by Arterial Spin Labeling Imaging in Patients With Moderate-to-Severe Stenosis Undergoing Carotid Endarterectomy

Purpose: To examine the associations between carotid plaque characteristics and perioperative cerebral blood flow (CBF) by arterial spin labeling (ASL) imaging.

Materials and methods: Patients with unilateral moderate-to-severe carotid stenosis referred for carotid endarterectomy (CEA) were recruited and underwent carotid vessel wall and brain ASL magnetic resonance imaging. The following imaging features were measured: relative CBF (rCBF = CBF_{index-hemisphere} /CBF_{contralateral-hemisphere} ) in the middle cerebral artery territory; plaque burden and the presence of lipid-rich necrotic core; intraplaque hemorrhage (IPH); calcification; ulcer and fibrous-cap rupture; and the volume and maximum plaque components' area percentages. The associations between plaque characteristics and perioperative CBF were analyzed.

Results: Sixty-one patients (mean age, 66.6 ± 7.8 years; 55 males) were included. Univariate linear regression showed that rCBF_pre-CEA was associated with stenosis [β, -0.462; 95% confidence interval (CI), from -0.797 to -0.126; p = 0.008], calcification (β, 0.103; 95% CI, 0.005-0.201; p = 0.040), maximum IPH area percentage (β, -0.127; 95% CI, from -0.223 to -0.030; p = 0.012), and ulcer (β, 0.069; 95% CI, 0.025-0.113; p = 0.005); rCBF_post-CEA was associated with the IPH volume (β, -0.060; 95% CI, from -0.107 to -0.014; p = 0.013). After adjusting for the confounding factors, the associations of calcification with rCBF_pre-CEA (β, 0.099; 95% CI, from 0.004 to -0.194; p = 0.042) and IPH volume with rCBF_post-CEA (β, -0.060; 95% CI, from -0.109 to -0.011; p = 0.020) remained statistically significant, while those of rCBF_pre-CEA with maximum IPH area percentage (β, -0.089; 95% CI, from -0.188 to 0.011; p = 0.080) and ulcer (β, 0.050; 95% CI, from -0.012 to 0.112; p = 0.100) did not remain statistically significant.

Conclusion: The compositional characteristics of carotid atherosclerotic plaques, particularly IPH, were associated with perioperative CBF in patients with unilateral moderate-to-severe carotid stenosis undergoing CEA. Our findings indicated that the patients with larger carotid IPH could expect smaller improvement in CBF following CEA.