The investigator propose, as a first step, to make a case-control study with these methods, the cases are patients who had an ischemic stroke (authenticated by both the clinical exam and brain MRI) on the same side as the carotid stenosis and the controls are patients with carotid stenosis but without ischemic stroke. This study is a cross-sectional study because it simultaneously measures the occurrence of the event (ischemic stroke) and the characteristics of the atheromatous plaque.