Nanotechnology and MRI contrast enhancement.

Technical advances in nanotechnology are creating novel classes of MRI contrast-enhancing agents. These nanomaterials offer much higher relaxivities than most current clinical contrast agents, which translates into greater MRI contrast enhancement. These nanoscale agents also have the potential to revolutionize in vivo applications of contrast-enhanced MRI since they offer the multiple advantages of low toxicities, extremely high relaxivities and cell internalization capabilities. In this review, we discuss three types of such contrast agents currently in use or under development for medical imaging: small particles of iron oxide, fullerenes encapsulating Gd(3+) ions (gadofullerenes) and single-walled carbon nanotube nanocapsules encapsulating Gd(3+) ion clusters (gadonanotubes). The latest developments and projected future applications of these nanotechnology-inspired contrast agents in the field of medical imaging are also discussed.