Abstract 42: Validation of a New Plaque-RADS Classification System to a Cohort of Embolic Stroke of Undetermined Source Patients

Abstract

Introduction: A new Plaque-RADS classification (I-IV) is proposed to categorize the degree of carotid plaque instability and risk of embolic ischemic stroke. We tested the Plaque-RADS classification in a cohort of patients with embolic stroke of undetermined source (ESUS) and imaged with neck CTAs. Methods: Patients with unilateral anterior circulation ischemic stroke due to ESUS and neck CTAs showing <50% carotid stenosis were retrospectively identified. Carotid total plaque thickness and ulceration were scored by a neuroradiologist blinded to stroke side. A semiautomated segmentation software measured intraplaque hemorrhage (IPH) volumes. The Plaque-RADS classification is defined as: I: no plaque; II: plaque thickness <3mm ; III: plaque thickness ≥ 3mm or ulcerated; and IV: plaque with IPH>50mL irrespective of thickness. Prevalence of Plaque-RADS subtypes was analyzed ipsilateral versus contralateral to stroke side. The proportion of low (subtypes I/II) versus high-risk (III/IV) carotid plaques on the ipsilateral versus contralateral stroke-side was tested using a McNemar’s test. Results: Ninety-four patients (N=52 female, mean age 65.4; N=188 plaques) met criteria. Plaque-RADS distribution was classified as: Plaque-RADS I: 18.1%; II: 44.7%; III: 36.7% (III ulc : 1.6%); IV: 0.5%. High-risk Plaque-RADS subtypes were significantly more prevalent on the ipsilateral (42.6%) compared to the contralateral side of stroke (31.9%, p=0.008). Conclusions: Carotid plaque ipsilateral to stroke side showed a higher proportion of Plaque-RADS III/IV subtypes. The Plaque-RADS classification may be used to risk-stratify carotid plaque phenotypes in patients with ESUS.