Abstract

Magnetic resonance imaging (MRI) has developed at an exponential rate over the last decades, and is now widely used as an anatomical and functional medical imaging modality. The development of magnetic nanoparticles as contrast agents for vascular, molecular, and cellular MRI applications has followed this trend. One of the most important direct applications of nanotechnology is nanoparticles which generate either “positive” or “negative” contrast in MRI. The present chapter is an introduction to the principles underlying the performance of nanoparticulate-based MRI contrast agents. It addresses the main considerations guiding the design, synthesis and the physicochemical characterization of magnetic nanoparticles based on the elements iron, manganese; and gadolinium (Fe, Mn, Gd). The fundamental aspects of nanoparticle magnetism and relaxometric characterization are introduced, as well as examples of applications in biological models.