Inclusion Criteria:  Age is greater than or equal to 18 years old and less than or equal to 80 years old; At least one imaging examination suggests the presence of carotid artery plaque; No allergy and other contraindications to ultrasound contrast; Contrast-enhanced ultrasound examination of carotid artery plaque is required; Volunteer to join this research project and sign informed consent.  Exclusion Criteria:  Patients who are unable to coordinate their body position or hold their breath during the ultrasound examination; Patients with severe lack of clinical data; During the follow-up, use drugs for the treatment of carotid plaque except lipid-lowering drugs, antiplatelet drugs, antioxidants, and calcium channel blockers; Follow up those who have lost contact; Ischemic stroke caused by non-carotid artery plaque shedding; Patients with atrial fibrillation and other serious heart diseases; A history of allergy to ultrasound contrast agents.