Metal-containing molecules and nanomaterials

For almost 40 years, complexes of gadolinium have formed a mainstay of diagnostic imaging through their use as contrast agents for magnetic resonance imaging. Once considered extremely safe, the emergence of nephrogenic systemic fibrosis in the 2000s challenged certain assumptions and practices. A feeling that the use of gadolinium in magnetic resonance imaging should be discontinued began to develop. However, alternatives have proven difficult to come by. Now some gadolinium-based agents have been removed from practice and new limitations have been introduced on how they are used. Recently, a new higher relaxivity contrast agent based on gadolinium has received approval and entered the market; another is currently in clinical trials. These developments suggest that the coordination chemistry advantages of gadolinium continue to make it the most likely candidate around which to develop newer, more effective, and safer contrast agents.