It is relatively easy to make a clinical diagnosis of acute ischemic stroke patients in terms of localization and characterization, but it is more difficult to diagnose the etiology. There is a lack of common diagnostic criteria for etiology at home and abroad. The heparin-like drug treatment for acute ischemic stroke trial (TOSAT) subtype classification criteria is currently the internationally accepted etiologic classification criteria for ischemic stroke. The TOAST subtype classification focuses on the etiology of ischemic stroke, and the theory of large and small vessel lesions based on this classification has played an important role in the study of the pathogenesis of cerebral infarction, which has been widely accepted since its publication in 1993. Currently, other commonly used classification methods for cerebrovascular disease include: Oxfordshire Community Stroke Project (OCSP) staging, which is based entirely on the clinical symptoms and signs of the patient in order to determine the location and severity of the infarct when imaging does not yet clearly show the infarct, and has the advantage of being quick, easy and reproducible. With the progress of neuroimaging technology, the site and size of the infarct can be clearly and accurately displayed, and thus imaging staging has emerged. Among the various clinical and imaging staging methods, the question of which staging criteria are most accurate for determining the etiology and prognosis of cerebral infarction as well as guiding treatment is of great clinical concern. Since the TOAST subtyping criteria focus on the etiological typing of ischemic stroke and have better credibility in clinical application, the TOAST typing method has been widely used in clinical practice. The results of studies on the clinical manifestations, regression, and rehabilitation of ischemic stroke using TOAST subtyping criteria have also shown that it helps clinicians to be more focused in the treatment and rehabilitation of patients with different subtypes of ischemic stroke. 1, TOAST subtype classification criteria According to the clinical characteristics and imaging and laboratory tests, TOAST classifies ischemic stroke into 5 types, each with different etiologies, as follows. 1.1, Large artery atherosclerosis (LAA) Patients with this type of stroke are found to have carotid artery occlusion or stenosis (stenosis ≥ 50% of the arterial cross-section) by carotid ultrasonography. Angiography or MRA shows ≥ 50% stenosis of the carotid, anterior cerebral, middle cerebral, posterior cerebral, and vertebrobasilar arteries. Its occurrence is due to atherosclerosis. Patients with the following manifestations are of great value for the diagnosis of LAA: 1) multiple transient ischemic attacks (TIA) in medical history, mostly multiple attacks in the same arterial supply area; 2) symptoms of aphasia, neglect, impaired motor function or symptoms of cerebellar or brainstem damage; 3) murmurs on carotid auscultation, diminished pulse, and asymmetry of blood pressure on both sides; 4) cranial CT or MRI examination may 4, cranial CT or MRI examination may reveal cortical or cerebellar damage, or subcortical or brainstem lesions >1.5 cm in diameter, which may be ischemic stroke due to underlying large arterial atherosclerosis; 5, color ultrasound, transcranial Doppler ultrasound (TCD), MRA or digital subtraction angiography (DSA) examination may reveal relevant intracranial or extracranial arteries and their branches with stenosis >50%, or occlusion; 6, should exclude Stroke due to cardiogenic embolism. 1.2, cardiogenic cerebral embolism (CE) This type refers to cerebral embolism caused by a variety of cardiac diseases that can produce cardiogenic emboli. 1, clinical presentation and imaging manifestations are similar to LAA; 2, history of multiple and multiple TIAs or strokes in the cerebrovascular supply area and other sites of embolism; 3, there are causes of cardiogenic emboli, at least one cardiogenic disease is present. 1.3, Small artery occlusive stroke or lacunar stroke (SAA) Patients with clinical and imaging manifestations with one of the following three criteria can confirm the diagnosis: 1. typical clinical manifestations of lacunar infarction and imaging with stroke lesions <1.5 cm in maximum diameter corresponding to clinical symptoms; 2. clinical symptoms of atypical lacunar infarction but no corresponding lesions found on imaging 3, clinically with atypical manifestations of lacunar infarction, while a lesion <1.5 cm corresponding to clinical symptoms is found after imaging. 1.4 , ischemic stroke from other causes (SOE) SOE is less common clinically, such as acute cerebral infarction due to infectious, immune, non-immune vascular disease, hypercoagulable state, hematologic disease, genetic vascular disease, and drug abuse. Such patients should have a clinical, CT or MRI examination showing the acute ischemic stroke lesion and the size and location of the lesion. Hematologic examination should be performed in cases of hematologic disease, and large and small arterial lesions as well as cardiogenic strokes should be excluded. 1.5 Ischemic stroke of unknown origin (SUE) The cause of this type of stroke has not been detected by multiple investigations. Among the above 5 etiologies, LAA, CE and SAA are the most common types in clinical practice and should be given high priority; SOE is less common in clinical practice and should be examined individually according to the patient's specific situation. The reliability of the TOAST subtype classification criteria is relatively low in early clinical application, reaching only 50%-70%. Due to the development of imaging techniques, such as CT, MRI and diffusion-weighted imaging (DWI), the compliance rate between the early ischemic stroke subtype classification and the final subtype classification has increased significantly. For example, early application of TCD examination can increase the confidence of early TOAST classification of ischemic stroke from 48% to 60%, and early application of DWI can increase the compliance rate of early TOAST classification to 80%, and if combined with MRA, the compliance rate can increase to 94%. This combined examination is particularly valuable for LAA and SAA, which can increase the early diagnostic compliance rate of LAA and SAA from 56% and 35% to 89% and 100%, respectively. The TOAST subtype classification criteria are of clinical value in classifying the early etiology of ischemic stroke, but clinical studies have shown that some patients still have difficulty in obtaining a definitive TOAST diagnosis 3 months after the onset of the disease. The reason for this may be that TOAST typing focuses on etiologic diagnosis, and the establishment of etiologic diagnosis requires some time for examination, observation and follow-up. In clinical work, laboratory and imaging examinations, as well as observation and follow-up of the disease require a certain amount of time, and only when these data are complete can a correct etiological diagnosis be obtained.