Nanoformulations for molecular MRI

Nanoscale contrast agents have shown the ability to increase the detection sensitivity of magnetic resonance imaging (MRI) by several orders of magnitude, endowing this traditionally macroscopic modality with the ability to observe unique molecular signatures. Herein, we describe three types of nanoparticulate contrast agents: iron oxide nanoparticles, gadolinium-based nanoparticles, and bio-essential manganese, cobalt, nickel, and copper ion-containing nanoformulations. Some of these agents have been approved for clinical use, but more are still under development for medical imaging. The advantages and disadvantages of each nanoformulation, in terms of intrinsic magnetism, ease of synthesis, biodistribution, etc. are discussed.