Inclusion Criteria1. 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 and a relevant intracranial atherosclerotic stenosis ≥60%.
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.
Exclusion CriteriaPatient with any of the following conditions would be excluded:
1. Stroke etiology uncertain or unrelated to intracranial atherosclerosis, such as cardioembolism, Moyamoya disease, small vessel disease or primary angiitis of CNS.
2. A tandem stenosis >50% at extra-cranial 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.