Morphology of Advanced Symptomatic Cerebral Plaques With High Embolic Potential

Inclusion Criteria: * Inclusion Criteria for the Symptomatic Group: 1. Patient is 30 to 85 years of age, inclusive. 2. Patients who have an acute infarct in diffusion-weighted MRI compatible with artery-to-artery thrombo-embolism, a relevant intracranial atherosclerotic stenosis ≥60%, and MES detected by TCD. 3. Patient who has no contra-indication for the proposed imaging tests. 4. Patient understands the purpose and requirements of the study, and has provided an informed consent. * Inclusion Criteria for the Asymptomatic Group: 1. Patient is 30 to 85 years of age, inclusive. 2. Patient who has a high-grade (\>60%) intracranial stenosis (signal void in MR angiography) but without infarct in the corresponding vascular territory in DWI or T2-weighted sequence. 3. Patient has no MES detected on TCD examination. 4. Patient who has no contra-indication for the proposed imaging tests. 5. Patient understands the purpose and requirements of the study, and has provided an informed consent. Exclusion Criteria: Subject who meets one or more of the following criteria cannot be recruited in the study: 1. Stroke etiology uncertain or unrelated to intracranial atherosclerosis, such as cardioembolism, Moyamoya disease, small vessel disease, etc. 2. A tandem stenosis \>50% at proximal internal carotid artery. 3. Bleeding propensity: active peptic ulcer disease, major systemic hemorrhage within 30 days, thrombocytopenia (platelets \<100 x 109/L), coagulopathy (INR \>1.5). 4. A medical condition that would not allow the patient to adhere to the protocol or complete the study.