Associations Between Carotid Plaque Characteristics and Improvement of Cerebral Blood Perfusion in Patients With Moderate to Severe Carotid Stenosis Undergoing Carotid Endarterectomy

Background: The relationship between plaque characteristics and their predictive value for perioperative cerebral blood flow (CBF) are unknown.

Purpose: To investigate the relationship between carotid plaque characteristics and perioperative CBF utilizing MRI.

Study type: Prospective.

Population: In all, 131 patients with carotid moderate-to-severe stenosis referred for carotid endarterectomy (CEA).

Field strength/sequence: 3T, black-blood T₁ - and T₂ -weighted, 3D time-of-flight, and simultaneous noncontrast angiography intraplaque hemorrhage.

Assessment: The relative CBF (rCBF = CBF_{index-hemisphere} /CBF_{contralateral-hemisphere} ) and the CBF difference ratio (DR_CBF = [CBF_post-CEA - CBF_pre-CEA ]/CBF_pre-CEA ) in the middle cerebral artery territory were measured. The pre- and post-CEA CTP data were used as the assessment standard for CBF change. Carotid lipid-rich necrotic core (LRNC), intraplaque hemorrhage, calcification, fibrous cap rupture, maximum wall thickness, normalized wall index (NWI), and stenosis were determined.

Statistical tests: Pearson or Spearman correlation, Mann-Whitney U-test, and linear regression.

Results: Patients with LRNC had higher rCBF_pre-CEA than those without (1.0 ± 0.1 vs. 0.9 ± 0.1, P < 0.05). NWI was weakly correlated with rCBF_pre-CEA (r = -0.213, P < 0.05) and DR_CBF (r = 0.185, P < 0.05) and marginally correlated with rCBF_post-CEA (r = 0.166, P = 0.057). LRNC was weakly correlated with rCBF_pre-CEA (r = 0.179, P < 0.05). NWI was associated with rCBF_pre-CEA (β = -0.035; 95% confidence interval [CI] [-0.064, -0.006]; P < 0.05), rCBF_post-CEA (β = 0.042; 95% CI [0.002, 0.081]; P < 0.05) and DR_CBF (β = 0.105; 95% CI [0.026, 0.185]; P < 0.05). After adjusting for confounding factors, associations of NWI with rCBF_post-CEA (β = 0.059; 95% CI [0.016, 0.103]; P < 0.05) and DR_CBF (β = 0.110; 95% CI [0.021, 0.199]; P < 0.05) remained statistically significant, while the association between NWI and rCBF_pre-CEA was no longer significant (β = -0.026; 95% CI [-0.058, 0.006]; P = 0.112).The associations of LRNC with rCBF_pre-CEA (β = 0.057; 95% CI [-0.0006, 0.114]; P = 0.052) and DR_CBF (β = -0.157; 95% CI [-0.314, 0.001]; P = 0.051) were close to statistical significance. After adjusting for confounding factors, these associations were statistically significant (of LRNC vs. rCBF_pre-CEA : β = 0.060; 95% CI [0.003, 0.118]; P < 0.05; LRNC vs. DR_CBF : β = -0.205; 95% CI [-0.375, -0.036]; P < 0.05).

Data conclusion: Carotid plaque burden and components, particularly LRNC, might be effective indicators for CBF change following CEA. Level of Evidence 1 Technical Efficacy Stage 5.