This study is aiming to provide us with information about the neuroprotective effect of two commonly used anesthetic drugs, during carotid endarterectomy. A day before sugery, a brain MRI will be performed as well as a cognitive function assessment test. The day of the surgery each patient will receive anesthesia either by using intravenous anesthetic drug or an inhalation agent and during the intraoperative period, the Anesthesiologist will draw a small amount of blood in three different times in order to measure brain biomarkers. A day after the surgery, a second brain MRI will be performed as well as a second cognitive function assessment test and their results will be compared to the preoperative ones. The study will focus on whether there is a higher incidence of microischemic brain lesions shown in imaging tests or whether cognitive function is impaired postoperative or whether brain biomarkers indicating brain damage are elevayed with any of these drugs and thus conclude which one shows or not a neuroprotective effect, with the condition that no change in the regular anesthesia management was made and no danger was imposed on the patient.