Arterial Spin Label Depicted Ischemic Stroke Cohort (ASLIS)

Inclusion Criteria: 1. Age 30-90, no gender restrictions. 2. Onset of disease ≤7 days. 3. Meet either of the following two conditions: ① Transient ischemic attack (TIA) ② Ischemia stroke (IS) Note: Acute IS diagnosis criteria: sudden and persistent focal or widespread neurological dysfunction, excluding other non-vascular causes of brain dysfunction (such as brain infection, head injury, brain tumor, epilepsy, severe metabolic diseases, or degenerative neurological diseases), confirmed by image as new IS. TIA diagnosis criteria: sudden and reversible focal neurological or retinal ischemic deficit caused by a reversible ischemia, usually lasting less than 24 hours, with no evidence of new IS on imaging, and excluding other non-ischemic causes (such as brain infection, head injury, brain tumor, epilepsy, severe metabolic diseases, or degenerative neurological diseases). 4. Signed informed consent Exclusion Criteria: 1. Clear cause of ischemic stroke other than atrial fibrillation. 2. Other ischemic strokes with a clear cause. 3. Presence of non-vascular intracranial disease. 4. Presence of severe systemic diseases. 5. Pregnancy or lactation. 6. Unable to tolerate or cooperate with MRI examination. 7. Unable to comply with follow-up due to geographical or other reasons.