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Leung K1.


Molecular Imaging and Contrast Agent Database (MICAD) [Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 2004-2013.
2011 Jun 11 [updated 2011 Sep 01].

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


Alzheimer's disease (AD) is a form of dementia with a gradual memory loss and a progressive decline in mental functions over time (1, 2). It is characterized pathologically by neuronal loss, extracellular senile plaques (aggregates of amyloid-β peptides consisting of 40–42 amino acids), and intracellular neurofibrillary tangles (filaments of microtubule-binding hyperphosphorylated protein tau) in the brain, especially in the hippocampus and associative regions of the cortex (3, 4). β-Amyloid peptides and tau proteins are implicated as the main causes of neuronal degeneration and cell death (5, 6). Early diagnosis of AD is important for treatment consideration and disease management (7). Various β-amyloid imaging agents have been developed for magnetic resonance imaging (MRI), single-photon emission computed tomography, and positron emission tomography (PET) (8-13) as measures of the presence of plaque. The binding of different derivatives of Congo red, thioflavin, stibene, and aminonaphthalene has been studied in human post-mortem brain tissue and in transgenic mice. Of these analogs, 2-(1-(6-[(2-[18F]fluoroethyl)(methyl)amino]-2-naphthyl)ethylidene)malono nitrile ([18F]FDDNP) was studied in humans, and it showed more binding in the brains of patients with AD than in those of healthy people (14). However, [18F]FDDNP showed low signal/noise ratios for PET imaging because it is highly lipophilic. N-Methyl-[11C]-2-(4’-methylaminophenyl)-6-hydroxybenzothiasole, a β-amyloid binding compound based on a series of neutral thioflavin-T derivatives (15), was radiolabeled with the positron-emitting radionuclide 11C ([11C]6-OH-BTA-1 or [11C]PIB). [11C]6-OH-BTA-1 was found to be a promising imaging agent for senile plaques in the brain (10). 5-(5-(2-(2-(2-[18F]Fluoroethoxy)ethoxy)ethoxy)benzofuran-2-yl)-N,N-dimethylbenzenamine ([18F]FPHBF-1) was found to exhibit good initial uptake but slow washout from the brain in normal mice, and thus it is not suitable for imaging studies. Ono et al. (16) reported the development of the less lipophilic monomethylamino derivative of [18F]FPHBF-1, 5-(5-(2-(2-(2-[18F]fluoroethoxy)ethoxy)ethoxy)benzofuran-2-yl)-N-methylbenzenamine ([18F]FPHBF-2) as a PET imaging agent for β-amyloid plaques in the brain.

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