Molecular MR imaging of atherosclerosis

In recent years, extensive research in atherosclerosis disease has elucidated many of the biological and molecular mechanisms and pathways involved in plaque development and progression. This has identified dozens of novel targets for diagnosis, therapy, and treatment evaluation. In vivo molecular imaging techniques, and in particular molecular magnetic resonance imaging (MRI), facilitate studies on the etiology of atherosclerosis and the evaluation of emerging therapies. In this chapter, we review contrast agents and (quantitative) MRI pulse sequences and strategies that have been developed for molecular MRI of atherosclerosis. We focus on targeted and nontargeted MRI contrast agents for specific imaging of inflammation (and especially macrophages), lipids, fibrous cap, thrombus, intra-plaque hemorrhage, apoptosis, and neovascularization. Contrast agents that are discussed include iron oxide-based agents (USPIO, MPIO), gadolinium- based materials (low molecular weight agents, micelles, liposomes, HDL-like particles) for 1 H MRI, as well as perfluorocarbon (PFC) emulsions for 19 F MRI. The most promising strategies for diagnosis (vulnerable, rupture-prone plaque detection), for determining therapeutic pathways, for monitoring of therapy, and for treatment personalization will be reviewed in more detail, discussing their value for preclinical research and clinical translation.