Imaging of atherosclerosis: invasive and noninvasive techniques.

Coronary artery disease (CAD), or narrowing of the coronary arteries due to atherosclerosis, remains one of the leading causes of morbidity and mortality worldwide. However, a substantial number of patients who present with an acute coronary event due to rupture or erosion of an atherosclerotic plaque do not experience any prior symptoms. This observation emphasizes the need to improve the early detection of atherosclerosis. Traditionally, imaging of the coronary arteries has focused on the assessment of luminal dimensions and the presence of severe stenosis by means of invasive coronary angiography. However, invasive coronary angiography can only assess the degree of stenosis and is less suited to evaluate the presence of atherosclerosis, including the presence of (potentially high-risk) plaques. As a result, there is an emerging need for imaging modalities that can identify atherosclerotic plaques with high-risk features indicating increased vulnerability. In this regard particularly, noninvasive techniques may be valuable, as they may identify high-risk patients at a relatively early stage and may provide the opportunity for novel treatment strategies. Additionally, noninvasive imaging techniques may be used to monitor progression and/or regression of coronary atherosclerosis and thus possibly to evaluate the effectiveness of anti-atherosclerotic therapies on a larger scale. Accordingly, the present review will focus on invasive and noninvasive imaging modalities for the evaluation of atherosclerosis and detection of vulnerable lesions in the coronary arteries.