Plaque Distribution and Characteristics in Low-Grade Middle Cerebral Artery Stenosis and Its Clinical Relevance: A 3-Dimensional High-Resolution Magnetic Resonance Imaging Study

Abstract

The significance of atherosclerotic plaques in the parental artery with low-grade stenosis remains undetermined. We used three-dimensional high-resolution magnetic resonance imaging (3D HR-MRI) to investigate plaque distribution and characteristics of low-grade middle cerebral artery (MCA) stenosis and its clinical relevance with stroke events. We retrospectively studied 22 symptomatic patients and 24 asymptomatic patients with low-grade MCA stenosis (<50%). By 3D HR-MRI, each identified plaque was classified as either culprit (plaque on the ipsilateral side of a stroke) or nonculprit (plaques in asymptomatic patients or not within the vascular territory of a stroke). Plaque enhancement grades and distribution were assessed and compared between the groups. The association between plaque enhancement and distribution and ischemic stroke was evaluated. We identified 22 culprit plaques and 31 nonculprit plaques. More culprit plaques showed contrast enhancement compared to the nonculprit plaques (95.5% versus 29.0%, P <.001). Culprit plaques were more frequently superiorly distributed than the nonculprit plaques (46.9% versus 17.5%, P <.01). Contrast enhancement (odds ratio [OR] 17.0, 95% confidence interval [CI] 3.7-77.4) and superior distribution (OR 4.2, 95% CI 1.4-12.1) of a plaque were associated with a recent ischemic stroke, of which single subcortical infarctions accounted for the largest percentage (50%). Contrast enhancement and superior distribution may serve as indicators of culprit plaques in low-grade MCA stenosis, and they were significantly related to a recent ischemic stroke.