Stroke caused by carotid atherosclerosis is a leading cause of mortality and the leading cause of disability in the developed world. For carotid plaques within the neurovascular territory of a recent stroke or transient ischaemic attack, surgical removal of the plaque (endarterectomy) has been clearly shown to reduce future cerebrovascular events. Management of asymptomatic plaques, however, is less clear because only a minority of these plaques will ultimately become symptomatic. Inflammation is a key feature which predicts whether a plaque is likely to rupture and hence lead to stroke. By identifying inflammation in vivo, positron emission tomography (PET) may be able to identify high risk plaques. This will allow clinicians to target intensive medical or surgical treatment to high risk patients.