Eligibility CriteriaInclusion Criteria: Hospitalized patients with age range ≥40 years and meet one of the following two criteria.
1. Patients with transient ischemic attack in recent 3 months.
2. Patients with ischemic stroke including acute and old cerebral infarction.
Exclusion Criteria1. cerebral hemorrhage;
2. vessel stenosis or occlusion caused by trauma,dissection or Takayasu's arteritis；
3. Stroke patients caused by patent foramen ovale.
4. Moyamoya disease;
5. Multiple sclerosis;
6. Mitochondrial myopathy.