Spider Versus Emboshield Distal Protection on Cerebral Microembolization During Vulnerable Plaque in Carotid Artery Stenting

Inclusion Criteria: 1. Male and female patients 18 years of age and older. 2. Symptomatic patients with internal carotid artery stenosis≥50% on angiography, or asymptomatic patients with internal carotid artery stenosis≥70% on angiography. 3. Anatomic characteristics of the lesions that made it possible to use either type of distal embolism protective device (Emboshield or Spider). 4. The lesion was located in the internal carotid artery (ICA) or the bifurcation of the carotid artery. 5. Only one WALLSTENT is expected to treat target lesions. 6. Tolerance to aspirin/clopidogrel/heparin and other drug therapy. 7. The patient or legally authorized representative has been informed of the nature of the study, agrees to its provisions, and has provided written informed consent, approved by the appropriate Medical Ethics Committee, Institutional Review Board, or Human Research Ethics Committee. 8. High-intensity Signal in the relevant plaques on the TOF-MRA. Exclusion Criteria: 1. Extensive ipsilateral or disabling stroke(mRS≥2) or cerebrovascular events occurred within 1 month combined with neurological defects. 2. Myocardial infarction occurred within 72 hours or TIA within 48 hours. 3. Atrial fibrillation (chronic or paroxysmal) is not treated with anticoagulation. 4. Ipsilateral intracranial artery stenosis with a history of stenting. 5. CABG or vascular surgery in the 30-day period before the procedure. 6. Acute coronary syndrome in the 30-day period before the procedure. 7. Life span within 12 months. 8. Patient has a history of bleeding diathesis within 1 month or coagulopathy or patients in whom antiplatelet and/or anticoagulant therapy is contraindicated. 9. Intolerance or allergic reaction to a study medication without a suitable management alternative. 10. The femoral artery condition is not good enough to enter the guidewire or the sound window is not good enough to conduct intraoperative TCD monitoring of the patient. 11. Unfavorable femoral artery anatomy for endovascular intervention or unfavorable acoustic window for intraoperative TCD monitoring. 12. With Intracranial tumor and is not considered suitable for inclusion or could not complete the MRI examination. 13. WBC\<3\*109/L, PLT\<50\*109/L or \>700\*109/L. 14. Pregnant or lactating female patient. 15. DSA indicated the target vessel occlusion; The tandem lesions could not be covered by one stent; The target vessel was seriously tortuous or the internal carotid artery was not suitable for WallStent; The aortic arch has severe calcification or tortuosity involving the common carotid artery or brachial trunk; Combined with cerebral AVM or cerebral aneurysms which need treatment; Carotid artery stenosis not caused by atherosclerosis, but arteritis, arterial dissection, congenital malformation of blood vessels, or severe vascular lesions after radiotherapy, etc..