To investigate the efficacy and safety of carotid stenting for vulnerable carotid plaques. All patients with carotid artery stenosis underwent carotid arterial contrast-enhanced ultrasonography before operation. According to the examination results, they were divided into two groups: vulnerable plaque group and stable plaque group. The incidence of perioperative stroke events in the two groups was compared. The incidence of stroke events in the two groups within 1 year was compared.

1. To enroll 100 cases of patients suffering from carotid artery stenosis。the investigators perform contrast enhanced ultrasound on patients for identifying the vulnerable plagues
2. The investigators divide patients into the stable group and the vulnerable group based on the results of CEUS inspection.
3. All patients undergo carotid stent. To analysis the incidence of postoperative complications such as stroke and mortality within 30 days and to compare the differences between the two groups.

Inclusion Criteria:

• The patients with ischemic symptom whose carotid stenosis were more than 50%
• The patients without ischemic symptom whose carotid stenosis were more than 70%

Exclusion Criteria:

• • Confirmed with severe intracranial vascular lesions

  • Suffering from the large area cerebral infarction or critical stroke sequela
  • Restenosis after CEA or CAS
  • Suffering from severe coronary heart disease, respiratory failure,the hypertension difficult to controled
  • Patients with malignant tumor or expected life < 2 years

the patients suffering from carotid artery stenosis