Which are the biotracers used for detection of Alzheimer's disease using PET?
Pittsburgh compound B (PIB) was the first radiotracer capable of highlighting deposits of beta-amyloid—one pathological hallmark of Alzheimer's disease—in living individuals during a PET scan. The Alzheimer's Association helped fund early PIB development. The Association in 2006 also awarded a $2.1 million grant to the Alzheimer's Disease Neuroimaging Initiative (ADNI) to expand this long-term, nationwide study to include PIB-PET imaging.

18F flutemetamol (flute), another radiotracer that highlights beta-amyloid in a PET scan, is structurally identical to PIB except for one fluorine atom in place of a carbon atom. That small chemical change enables flutemetamol to remain stable significantly longer than does PIB, potentially increasing its usefulness outside research settings. In phase II study results reported in the Annals of Neurology, flutemetamol performed similarly to PIB. Additional testing is under way.

Florbetapir F 18 (18F-AV-45) is also a radiotracer that highlights brain beta-amyloid during a PET scan. At the 2010 Alzheimer's Association International Conference on Alzheimer's Disease (AAICAD), florbetapir's developer first reported data, later published in the JAMA, showing nearly perfect correlation between brain amyloid levels detected by florbetapir PET scans in study volunteers and levels found in autopsies of the same individuals a few months later. The developer has sought Food and Drug Administration (FDA) approval to market florbetapir under the brand name Amyvid. The FDA has said it will withhold approval until the developer establishes a professional training program to ensure accuracy and consistency in reading and interpreting Amyvid scans.

Florbetaben (BAY 94-9172) is another radiotracer designed to detect beta-amyloid during a PET scan. Phase II study results and other florbetaben data were reported at the 2010 Alzheimer's Association International Conference on Alzheimer's Disease (AAICAD). Phase II data were also later published in Lancet Neurology. Further studies are now under way.