Nanotechnology has made possible the production of Nanoparticles. NPs can be made of different materials such as ceramics, carbon and various metals. It also can take different shapes. They can be used in imaging and also to transport drugs. They can be widely used in imaging but in the case of Brain Imaging, its main use is to facilitate the passage of a tracer or drug across the blood brain barrier BBB. The basic mechanism of action is that the NPs bind to a receptor at the surface of the cell and the whole structure (NPs+tracer or NPs+drug) is transported by endocytosis and then released to the brain. NPs can be also targeted to specific molecules. In the case of tumors there is an extra advantage since the vascular leakage is higher and the lymphatic drainage is impaired, which promotes accumulation of the NPs.
In my opinion, Nanoparticles are a new technology with great promise, since imaging and drug delivery to the brain has long been hampered by the problem of BBB impermeability. Many drugs and tracers with great potential usefulness have had to be discarded in the past because they were unable to reach their target due to BBB impermeability. Hopefully this will no longer be a problem when using NPs in many instances. The following is a good paper on the topic:
Provenzale, JM etal., Uses of Nanoparticles for Central Nervous System
Imaging and Therapy, Am J Neuroradiol 2009 Aug 30(7) 1293-301.
Adolfo Cotter, MD
Jul 05/2010
Adolfo Cotter,MD 
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