Cranial CT examination: Once a stroke is diagnosed, the type of stroke, such as hemorrhagic or ischemic stroke, needs to be clarified as soon as possible. Because the treatment principles of the two are opposite, an incorrect sexual determination may result in unfavorable images for subsequent treatment. A cranial CT is not only quick and easy, but also provides additional information; the presence or absence of high-density or low-density shadows on the cranial CT is used to determine whether the stroke is hemorrhagic or ischemic. Hemorrhagic strokes are intracranially dense and ischemic strokes are hypointense. Of particular note is the hyperacute phase, where within 6 hours of onset, an ischemic stroke can appear as a normal cranial CT image without hypointense shadowing, because cerebral infarcts tend to be delayed on imaging, and such infarcts often do not manifest themselves until several hours later. However, cranial CT also has disadvantages, such as posterior circulation infarction including infarction of the brainstem and cerebellum, where the presence of infarction or hemorrhage cannot be clearly identified due to interference caused by artifacts of bone. Further examination with MRI should be performed when hemorrhage or infarction is suspected. Cranial magnetic resonance (MRI): MRI reflects the location of stroke more clearly than cranial CT, and responds to the characteristics of infarction or hemorrhage by different phases T1, T2 and DWI phases. However, there are corresponding disadvantages, such as relatively time-consuming and possible missed diagnosis for hyperacute phase hemorrhage. MRI also has other advantages, such as the possibility of combining perfusion imaging to observe the mismatch between infarct and ischemic extent to decide whether to perform further thrombolysis or intervention. CT or MRI vascular evaluation: Both cranial CT and MRI can perform vascular evaluation, especially when the onset is severe and severe stenosis or occlusion of the vessel can be seen on imaging. This talk total image is not seen by conventional CT or MRI. The Changhai Cerebrovascular Disease Center now mainly uses cranial CT angiography (CTA) for responsible vascular determination, which can directly perform cranial CT angiography to determine the characteristics of cerebrovascular lesions, integrating conventional and angiography examinations, from CT scan to vascular determination in just a few minutes to instantly observe the type of stroke and corresponding vascular lesion images, so that doctors can quickly make corresponding treatment decisions. Some hospitals also choose MRI angiography, but it takes a little longer than CT. Cerebral angiography: Cerebral angiography is the gold standard of imaging. This test is similar to a cardiac angiogram. A puncture is made through the femoral artery and a very fine catheter is then used to travel through the vessel, contrast is applied to the lesion and then the vascular lesion features are viewed under X-ray. In hyperacute stroke, cerebral angiography is integrated with treatment when embolization is needed in case of suspected stenosis or occlusion by CTA. The first choice is cranial CT for hyperacute stroke; 2. Angiography can determine the responsible vessel, unlike conventional CT; 3.