Patients undergo carotid ultrasound examinations either due to symptomatic presentations such as transient ischemic attacks, dizziness, visual disturbances, or stroke-like symptoms, or as part of preventive screening protocols for high-risk populations. High-risk groups include individuals over 65, patients with diabetes, hypertension, cardiovascular disease, family history of stroke, smokers, and those with neck bruits, with some healthcare systems also implementing population-based screening programs for stroke prevention.