MRI, the technology for imaging of thrombi and inflammation

Atherosclerosis and its sequelae have a major impact on morbidity and mortality. The rupture of an inflamed atherosclerotic plaque is a crucial event, since it can result in acute thrombotic closure of an arterial vessel, resulting e. g. in myocardial infarction or stroke. Not only detection of early plaque rupture with imminent closure is therefore of clinical interest, but also timely detection of vascular inflammation and atherosclerotic plaque progression. However, plaque inflammation or even plaque rupture without vessel occlusion is not reliably detectable by current imaging techniques. Coronary angiography is the gold standard for evaluation of the coronary vessels, but only allows visualization of the vessel lumen without characterizing the important pathophysiology of the vessel wall. Therefore, highly inflamed and rupture prone plaques can be missed, or appear as a minor vessel narrowing. Although currently available techniques such as intravascular ultrasound or optical coherence tomography allow a further characterization of atherosclerotic plaques, it would be desirable to detect plaque inflammation, early plaque rupture or vascular thrombosis by non-invasive techniques such as magnetic resonance imaging (MRI), since they could allow early identification of patients at risk or triage of symptomatic patients. In this manuscript, different strategies for detection of vascular inflammation, plaque-rupture and thrombosis by MRI will be discussed, with a special focus on molecular imaging contrast agents.