It used to be axiomatic that atherosclerosis was continuous, cumulative, and irreversibly associated with aging. However, since 1989, when the first evidence of treatmentinduced lesion regression was obtained in animals, it has become increasingly apparent that the ultimate challenge—reversal of established atherosclerosis—is feasible. Intervention studies depend on accurate measurement not only of plaque dynamics, but increasingly of plaque composition and metabolic activity. It is important to be able to identify vulnerable plaques. In addition to intravascular ultrasound and its derivatives, merged modalities have been developed to provide valuable molecular and metabolic imaging, eg, using fluorodeoxyglucose positron emission tomography or ultrasmall superparamagnetic iron oxide nanoparticles and multidetector computed tomography...