At the time of carotid endarterectomy, which is an established surgical intervention aimed at reducing the future risk of stroke in symptomatic patients, tissue will be collected, and lesion integrity and geometry will be preserved as much as possible. Specimens will be photographed in detail to permit subsequent assessment by independent and blinded reviewers. The excised tissue will be aligned and labelled to permit orientation in the carotid artery axis before undertaking 7.4 T magnetic resonance spectroscopy. Subsequently, carotid plaque will be snap frozen in liquid nitrogen. Cellular content, macrophage infiltration, apoptosis, and calcification-associated molecules within the plaques will be assessed by RNA analysis, immunohistochemistry and immunofluorescence using a variety of validated markers.