Abstract 2220: 3T Magnetic Resonance Imaging Identifies Unstable Carotid Atherosclerotic Plaque in the Very Early Phase of Acute Stroke
Introduction Ipsilateral carotid stenosis is associated with a high risk of recurrent stroke in the acute phase - approximately 8% at one week. Magnetic Resonance Imaging (MRI) of the carotid artery can provide detailed information on atherosclerotic plaque structure, but to date has not been used in the period immediately following acute stroke. Hypothesis 3T MRI can identify unstable plaque in patients presenting with transient ischemic attack (TIA) or minor stroke.
Methods 20 patients presenting with TIA or minor stroke underwent T1-, T2-, and proton density (PD)-weighted turbo spin echo imaging to 10mm either side of the carotid bifurcation (in-plane resolution 0.47mm x 0.47mm), and time-of-flight (TOF) MR angiography. Plaques were graded according to the MRI modified AHA system; statistical analyses were performed using chi-squared and Mann-Whitney tests.
Results and Conclusion 14/20 patients were male (age [mean ± SD] 68.9±21.4); median time from symptom onset to imaging was 46 hours. Plaque characterisation was technically feasible in 292/353 (83%) images. Type VI plaque was seen in 10 cases and was more prevalent in the culprit carotid artery than the contralateral artery (10 vs. 0; p=.001). Of these 10 plaques, 6 showed evidence of surface disruption (panel A), 1 had associated intra-luminal thrombus (panel B), and 3 showed bright signal suggestive of intraplaque hemorrhage (panel C). In conclusion, we present the first study demonstrating the ability of 3T MRI to show the early features of ruptured plaque in an acutely symptomatic population; further work will determine the utility of this technique in guiding secondary prevention therapy.