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Background Studies have shown that pericoronary artery inflammation can be accurately detected via increased attenuation on computed tomography. Our purpose was to evaluate the association between pericarotid inflammation, measured by density of carotid perivascular fat on computed tomography angiography, with stroke and transient ischemic attack. Methods and Results We screened computed tomography angiography examinations for patients with unilateral internal carotid artery (ICA) stenosis ≥50% to 99%. A blinded neuroradiologist placed regions‐of‐interest in the pericarotid fat on the slice showing maximal stenosis. Two‐sample t tests were performed to assess between‐subject differences in mean Hounsfield Units in carotid perivascular fat between symptomatic and asymptomatic patients. Paired t tests were used to assess within‐subject differences in mean Hounsfield Units between stenotic versus nonstenotic ICAs in a given patient. We included 94 patients, including 42 symptomatic and 52 asymptomatic patients. In the between‐subject analysis of stenotic ICAs, we found symptomatic patients had higher mean pericarotid fat density compared with asymptomatic patients (−66.2±19.2 versus −77.1±20.4, P=0.009). When comparing nonstenotic ICAs, there was no significant difference between pericarotid fat density in symptomatic compared with asymptomatic patients (−81.0±13.3 versus −85.3±18.0: P=0.198). Within‐subject comparison showed statistically significant increased density in stenotic ICA versus nonstenotic ICA with mean Hounsfield Units difference of 11.1 (P

BackgroundGadolinium enhancement on high‐resolution magnetic resonance imaging (MRI) has been proposed as a marker of inflammation and instability in intracranial atherosclerotic plaque. We performed a systematic review and meta‐analysis to summarize the association between intracranial atherosclerotic plaque enhancement and acute ischemic stroke. Methods and ResultsWe searched the medical literature to identify studies of patients undergoing intracranial vessel wall MRI for evaluation of intracranial atherosclerotic plaque. We recorded study data and assessed study quality, with disagreements in data extraction resolved by a third reader. A random‐effects odds ratio was used to assess whether, in any given patient, cerebral infarction was more likely in the vascular territory supplied by an artery with MRI‐detected plaque enhancement as compared to territory supplied by an artery without enhancement. We calculated between‐study heterogeneity using the Cochrane Q test and publication bias using the Begg‐Mazumdar test. Eight articles published between 2011 and 2015 met inclusion criteria. These studies provided information about plaque enhancement characteristics from 295 arteries in 330 patients. We found a significant positive relationship between MRI enhancement and cerebral infarction in the same vascular territory, with a random effects odds ratio of 10.8 (95% CI 4.1–28.1, P