Vascular Wall Imaging by MRI

Magnetic resonance imaging (MRI) of the arterial wall yields a surrogate marker for atherosclerosis, which can provide an early indication of cardiovascular disease risk and enables assessing the efficacy of novel cardiovascular drugs. In this overview, we address the technical requirements and the clinical relevance of vessel wall MRI. We describe the use of “black blood” imaging sequences, which are needed for good discrimination between the lumen and the artery wall. Furthermore, we discuss how multiple contrast weighted imaging can enable us to visualize components within the plaque to help us predict which plaques are prone to rupture and would cause cerebrovascular events. We also touch on the use of contrast agents for imaging biological processes in atherosclerosis. Dynamic contrast enhanced MRI performs a kinetic analysis of the uptake of gadolinium-based contrast agents in the atherosclerotic plaque and estimates the area and permeability of microvessels in the plaque. Ultra small particle iron oxide is another contrast agent that can enter the plaque where it is specifically taken up by macrophages, and thus reflects plaque macrophage content. Novel developments in this area include the employment of lipoprotein bearing contrast agents and the use of particles that contain contrast agents, as well as ligands targeting a specific molecule. In experimental studies, this “molecular imaging” approach has been proved to enable visualization of cellular and molecular targets in atherosclerosis. This can be of great use in enhancing our understanding of the atherosclerotic disease process and evaluating therapy in the future.