Stent Retriever's(TonbridgeMT) Endovascular Therapy for Acute Ischemic Stroke(AIS)

Inclusion Criteria: 1. 18≤ages≤80; 2. Baseline NIHSS score obtained prior to randomization must be lower than 30 points; 3. Acute occlusion(TICI 0-1) of the intracranial segment of internal carotid artery(ICA), or M1/M2 middle cerebral artery(MCA), or A1/A2 anterior cerebral artery(ACA), as evidenced by digital subtraction angiography(DSA); 4. Patient treatable within 6 hours of symptom onset(symptoms onset is defined as point in time the patient was last seen well (at baseline)) can accept the complete femoral artery puncture; 5. Pre-AIS mRS score lower than 2. Exclusion Criteria: 1. Computed tomography (CT) or magnetic resonance imaging (MRI) evidence of intracranial hemorrhage or massive cerebral infarction (ASPECTS score of\<6 or infarct volume≥70ml or volume\>1/3 blood supplying areas of MCA on CT/diffusion weighted imaging(DWI); 2. DSA evidence of simultaneous acute bilateral carotid occlusion; 3. DSA evidence of occlusions in the initial segment of carotid artery or carotid artery dissection or arteritis; 4. DSA evidence of tortuosity of cervical vessels precluding device delivery/deployment; 5. Hypertension (Systolic blood pressure(SBP)\>185 mm Hg or diastolic blood pressure(DBP)\>110 mm Hg) after using drug; 6. Platelet count\<40,000/μL and use of Novel Anticoagulant with International Normalized Ratio(INR)\>3.0; 7. Random blood glucose of\<2.7mmol/L or\>22.2mmol/L; 8. Patients with heart or lung or liver or renal failure or other sever disease(intracranial tumors, cerebral arteriovenous malformation (AVM), systemic infection, active disseminated intravascular coagulation, myocardial infarction within the past 12 months before enrollment, history of sever psychosis); 9. Patients who will not cooperate or tolerate interventional operation; 10. Anticipated life expectancy of less than 90 days; 11. Allergy to contrast medium; 12. Females who are pregnant or breastfeeding; 13. Participation in any other clinical trial within the past 1 months before screening and follow-up; 14. The patient or the patient's legally authorized representative hasn't signed and dated an informed consent form; 15. Other factors that would cause harm or increased risk to the participant or close contacts, or preclude the participant's full adherence as per investigator's judgement.