A new way of scanning narrowing in the arteries (main blood vessels) caused by fatty deposits known as plaques has been developed. Heart attacks and strokes occur when plaques become inflamed, depending on the artery affected. Currently used clinical tests can only tell us how much the vessel is blocked by the plaque and not how inflamed (i.e. dangerous) it is. This new method of scanning using magnetic resonance imaging (MRI) and a special agent called Sinerim can identify inflamed plaques. This study will evaluate patients with plaques in their arteries in their neck at risk of strokes to see whether treatment with a cholesterol-lowering drug called atorvastatin can reduce the amount of inflammation within the artery wall within the first three months of treatment. If this effect can be measured using MRI scanning with the use of Sinerim then the results of this study will provide additional clinical validation of the use of MRI scanning combined with agents such as Sinerem®.