The first goal of this study is to investigate whether CE-US is able to accurately identify and quantify neovascularisation in carotid artery plaques. Since this is one of the first studies systematically evaluating the ability of ultrasound in combination with air bubbles to evaluate neovascularisation in carotid artery plaques, the examination will be performed twice with an interval of 1/2 hour on the day before surgery, thus studying the reliability of the method.