The goal of this prospective diagnostic accuracy cohort study is to compare the accuracy of carotid atherosclerotic plaques stiffness assessed by shear wave elastography (SWE) with greyscale median values (GSM), magnetic resonance imaging (MRI) and histopathological findings in patients with carotid atherosclerotic plaques causing stenosis above 50%, symptomatic or not.

The main question it aims to answer is: is the plaque stiffness correlatable with GSM values, MRI findings or histopathological findings? Participants will be subjected to a vascular ultrasound study in which the SWE and GSM will be assessed. The second imaging modality for stenosis confirmation will be MRI and patients with confirmed symptomatic stenosis above 50% or assymptomatic stenosis above 70% will be considered for surgery intervention (endarterectomy or angioplasty). Patients that undergo endarterectomy will have the carotid plaques subjected to a histopathological study. The study will not arbitrate about the treatment decision.

Inclusion Criteria:

• Patients with atherosclerotic carotid plaques that develop stenosis superior to 50%.

Exclusion Criteria:

• Previous cervical surgery;
• Previous cervical radiotherapy;
• Stenosis caused by vascular inflammatory diseases;
• Pregnant women;
• High carotid bifurcation (inaccessible by vascular ultrasound linear probe);
• Posterior acoustic shadowing that impair morphological evaluation of the plaque.

The study population will be composed of outpatient care subjects referred to the Noninvasive Vascular Laboratory of the Hospital das Clinicas da Faculdade de Medicina de Botucatu for vascular appointments or vascular ultrasound assessment for carotid atherosclerotic disease.