Background Supracardiac atherosclerosis is a major cause of stroke. Although vessel wall MRI (vwMRI) can assess plaques, current techniques lack full head-neck-aortic arch coverage and efficiency. Purpose To develop and evaluate a head-neck-aortic vwMRI protocol for supracardiac atherosclerosis, compare its performance with that of supra-aortic CT angiography (CTA), and determine its feasibility in helping identify causes of embolic stroke of undetermined source (ESUS). Materials and Methods We