Invasive imaging techniques for the assessment of vulnerable plaque

Coronary artery disease is the leading cause of mortality and morbidity in the Western world and an ever-increasing problem in developing countries. Unheralded acute coronary syndromes (ACS) are common initial manifestations of coronary atherosclerosis and are often caused by lesions which have previously not generated symptoms. Histopathological studies have identified several plaque morphologies associated with ACS. However, the natural history of these high-risk or vulnerable lesions remains unknown and the limited knowledge about their eventual prognosis is provided by retrospective histopathological studies. Detection of these vulnerable plaques in vivo is essential to study their natural history and to evaluate potential treatment modalities and, therefore, may ultimately have an important impact on the prevention of acute myocardial infarction and death. Currently, there are several diagnostic imaging tools capable of evaluating determinants of plaque vulnerability. These techniques can provide information on the vessel lumen and wall size, tissue composition and the status of inflammation. This article aims to review the current status of these imaging techniques.