This study explores the value of the non-invasive quantitative evaluation system for cerebral blood flow perfusion function in the diagnosis of stroke. Compared with traditional perfusion techniques, multi-delay arterial spin labeling (ASL) is validated to determine the accuracy of perfusion level, ischemic penumbra and other indexes in patients with acute ischemic stroke. The relationship between perfusion levels of mD-ASL parameters and clinical outcome is also studied.

A total of 200 patients with acute anterior circulation ischemic stroke will be prospectively enrolled.

All patients underwent CTP, multi-delay ASL, DWI, CTA or TOF-MRA scanning. CBF, CBV, MTT and Tmax will be obtained based on CTP, and the range of reversible cerebral ischemia injury will be calculated based on DWI and CTP data. CBF, CBV and ATT images will be obtained based on the multi-delay ASL, and the calculated results of reversible cerebral ischemia injury will also be obtained.

Meanwhile, the image quality of CTP and multi-delay ASL will be evaluated. The time from the patient to the completion of imaging examination and the imaging examination time will be recorded.

Mann-whitney U test and T test can be used to compare the difference of assessment time between different test methods. Chi-square test can be used to compare the differences of image quality among different examination methods. Wilcoxon rank sum test can be used to evaluate the difference between CTP and Multi-delay ASL in terms of parameters and volume of reversible ischemic injury.

Inclusion Criteria:

1. Ischemic stroke within 24h；
2. Anterior circulation occlusion confirmed by conventional angiography or magnetic resonance angiography；

Exclusion Criteria:

1. Pregnancy and other contraindication to MRI scan；
2. Informed consent not obtained.

Patients with acute anterior circulation ischemic stroke without contraindication to MRI will be enrolled.