The VAST study is a single-center prospective observational study that enrolled individuals with acute ischemic stroke (AIS) within 24 hours onset. The patients will receive neurological examination, multimodal computed tomographic perfusion (CTP) or multimodal magnetic resonance perfusion (MRP) before reperfusion therapy. The hypoperfusion volume, ischemic core volume, brain edema, cerebral arterial collaterals will be evaluated on baseline brain image. The status of cerebral venous system (CVs) including superficial middle cerebral vein, vein of Labbe, vein of Trolard, Sphenoid sinus, thalamostriate vein, Internal cerebral vein, Rosenthal's vein will be evaluated in phases of reconstructed imaging from CTP/MRP. The investigators will explore the venous markers for prognosis of AIS patients who received reperfusion therapy, and find the role of venous system in reperfusion injury.

Stroke therapy had entered a new era since endovascular therapy was introduced in addition to intravenous thrombolysis. The benefit of endovascular therapy for patients with a proven proximal intracranial arterial occlusion has recently been revealed in several large randomized controlled trials. However, a substantial number of patients treated with reperfusion therapy did not reach functional independence in long-term follow-up, despite relatively high recanalization rates. Therefore, simple and more reliable markers that identify patients most likely to benefit from reperfusion therapy are needed. Accumulated studies showed that arterial status such as arterial collaterals had been considered as a critical predictor of outcome or determinant criteria for therapeutic selection. However, other evidences denied that arterial collaterals serve as a predictors for outcome after recanalization. Moreover, non-reflow phenomenon, over-reperfusion and futile recanalization may lead to large infarct, brain swelling, hemorrhagic complication and neurological deterioration. The traditional pathophysiological understanding on ischemic stroke can hardly explain these occurrences. Recently, the importance of cerebral venous drainage, the major blood reservoir and drainage system in brain, has been described for stroke evolution and clinical sequelae. In this study, the aim is to investigate the roles of cerebral venous dynamic status on neurological outcome after reperfusion therapy and the potential mechanisms behind poor veins and adverse outcome. In this study, the investigators will prospectively recruit the AIS patients over 18 years old who undergo baseline CTP/MRP and receive reperfusion therapy within 24 hour after onset. Each of their perfusion imaging will be reconstructed to evaluate the status of cerebral vein system. The investigators hypothesized that the venous dynamic status may have effect on the ischemic-reperfusion progress, and may thus has the potential to impact the stroke outcome. This study may add new implications for stroke outcome prediction and future therapeutic decision-making.

Inclusion Criteria:

1. receive reperfusion therapy within 24 hours after onset;
2. undergo multimodal magnetic resonance computed tomography before reperfusion therapy and CTP or magnetic resonance perfusion at 24 hours after reperfusion therapy;

Exclusion Criteria:

1. Contraindication to imaging with contrast agents;
2. Without provision of informed consent.

acute ischemic stroke patients