Atherosclerosis is a systemic, lipid-driven inflammatory disease of the arterial wall leading to multifocal plaque development. The most dangerous plaques are those causing thrombosis, socalled vulnerable plaques. Most thrombi leading to heart attack and large artery stroke are caused by plaque rupture. A ruptured plaque contains a large and soft lipid-rich necrotic core covered by a thin and inflamed fibrous cap. Associated features include big plaque size, expansive remodeling mitigating luminal obstruction (mild stenosis by angiography), neovascularization (angiogenesis), plaque hemorrhage, adventitial inflammation, and a "spotty" pattern of calcifications. These features are potential targets for detection of vulnerable plaques by imaging.