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Leung K1.


Molecular Imaging and Contrast Agent Database (MICAD) [Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 2004-2013.
2007 Oct 06 [updated 2007 Nov 19].

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National Center for Biotechnology Information, NLM, NIH, Bethesda, MD, Email:


Alzheimer’s disease (AD) is a major neurodegenerative disease associated with an irreversible decline of mental functions and with cognitive impairment (1). It is characterized pathologically by neuronal loss with the presence in the brain of senile plaques of β-amyloid (Aβ) peptides and intracellular neurofibrillary tangles of filaments that contain the hyperphosphorylated protein tau (2, 3). Accelerated deposition of Aβ deposits seems to be a key risk factor associated with AD. Early diagnosis of AD is important for treatment consideration and disease management (4). Several radioligands [PubMed] for positron emission tomography (PET) have been developed (5-7) and tested in humans as in vivo diagnostic tools for imaging and measuring the formation of Aβ deposits (7). The first agent successfully used in human studies was [18F]FDDNP (8), a malonitrile derivative found to bind to both neurofibrillary tangles and Aβ plaques. The second successful agent was [11C]PIB (9), also known as Pittsburgh Compound B or [11C]6-OH-BTA-1, which showed marked retention in areas of the cortex known to contain substantial amounts of Aβ deposits. The third PET radioligand successfully tested in humans was [11C]4-N-methylamino-4’-hydroxystilbene ([11C]SB-13), a stilbene derivative that exhibits good binding affinities for Aβ aggregates in vitro, moderate lipophilicity, high initial brain uptake in the normal rat cortex, and a rapid washout (10). [125I]6-Iodo-2-(4’-dimethylamino)-phenyl-imidazo[1,2-a]pyridine ([125I]IMPY) displays a high specific binding for Aβ plaques and favorable brain uptake kinetics in rodents for single-photon emission computed tomography (SPECT). [S-methyl-11C]N,N-Dimethyl-4-(6-(methylthio)imidazo[1,2-a]pyridine-2-yl)aniline ([11C]MeS-IMPY) has been synthesized as an S-methyl analog of [125I]IMPY and is currently being studied as a PET radioligand for Aβ plaques (11).

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