This chapter provides the basic cost-effectiveness decision analysis methodology and terminology for carotid imaging. The main focus of economic analyses has been the cost-effectiveness of screening programmes for more than 60% stenosis based on the results of the asymptomatic carotid atherosclerosis study (ACAS) trial. The cost-effectiveness analysis model typically starts with the reference case, which would usually be a typical hypothetical patient who has suffered from a minor stroke or a transient ischemic attack. A decision-tree model is essentially a horizontal flow chart that depicts all the decisions, chance events and outcomes that stem from an initial set of imaging options. There have been several studies reporting on the cost-effectiveness of carotid imaging modalities prior to surgery. In asymptomatic patients, cost-effectiveness analysis studies have generally focussed on the cost-effectiveness of screening for the identification of more than 60% stenosis based on the results of the ACAS trial.