Carotid plaque inflammation on 18F-fluorodeoxyglucose positron emission tomography predicts early stroke recurrence

Symptomatic carotid stenosis is associated with a 3-fold risk of early stroke recurrence compared to other stroke subtypes. Current carotid imaging techniques rely on estimating plaque-related lumen narrowing but do not evaluate intraplaque inflammation, a key mediator of plaque rupture and thromboembolism. Using combined (18) F-fluorodeoxyglucose positron-emission tomography (FDG-PET)/computed tomography, we investigated the relation between inflammation-related FDG uptake and stroke recurrence.

Consecutive patients with a recent (median, 6.5 days; interquartile range, 4-8) stroke, transient ischemic attack (TIA), or retinal embolism and ipsilateral carotid stenosis (≥50%) were included. FDG uptake was quantified as mean standardized uptake values (SUVs, g/ml). Patients were followed prospectively for stroke recurrence.

Sixty patients were included (25 stroke, 29 TIA, 6 retinal embolism). Twenty-two percent (13 of 60) had stroke recurrence within 90 days. FDG uptake in ipsilateral carotid plaque was greater in patients with early recurrent stroke (mean SUV, 1.85 g/ml; standard deviation [SD], 0.44 vs 1.58 g/ml; SD, 0.32, p = 0.02). On life-table analysis, 90-day recurrence rates with mean SUV greater than a 2.14 g/ml threshold were 80% (95% confidence interval [CI], 41.8-99.2) versus 22.9% (95% CI, 12.3-40.3) with SUV ≤2.14 g/ml (log-rank, p < 0.0001). In a Cox regression model including age and degree of stenosis (50-69% or ≥70%), mean plaque FDG uptake was the only independent predictor of stroke recurrence (adjusted hazard ratio, 6.1; 95% CI, 1.3-28.8; p = 0.02).

In recently symptomatic carotid stenosis, inflammation-related FDG uptake was associated with early stroke recurrence, independent of the degree of stenosis. Plaque FDG-PET may identify patients at highest risk for stroke recurrence, who may be selected for immediate revascularization or intensive medical treatment.