Positron emission tomography radiopharmaceuticals for imaging brain Beta-amyloid.

Abstract

Alzheimer's disease (AD) is defined histologically by the presence of extracellular β-amyloid (Aβ) plaques and intraneuronal neurofibrillary tangles in the cerebral cortex. The diagnosis of dementia, along with the prediction of who will develop dementia, has been assisted by magnetic resonance imaging and positron emission tomography (PET) by using [(18)F]fluorodeoxyglucose (FDG). These techniques, however, are not specific for AD. Based on the chemistry of histologic staining dyes, several Aβ-specific positron-emitting radiotracers have been developed to image neuropathology of AD. Among these, [(11)C]PiB is the most studied Aβ-binding PET radiopharmaceutical in the world. The histologic and biochemical specificity of PiB binding across different regions of the AD brain was demonstrated by showing a direct correlation between Aβ-containing amyloid plaques and in vivo [(11)C]PiB retention measured by PET imaging. Because (11)C is not ideal for commercialization, several (18)F-labeled tracers have been developed. At this time, [(18)F]3'-F-PiB (Flutemetamol), (18)F-AV-45 (Florbetapir), and (18)F-AV-1 (Florbetaben) are undergoing extensive phase II and III clinical trials. This article provides a brief review of the amyloid biology and chemistry of Aβ-specific (11)C and (18)F-PET radiopharmaceuticals. Clinical trials have clearly documented that PET radiopharmaceuticals capable of assessing Aβ content in vivo in the brains of AD subjects and subjects with mild cognitive impairment will be important as diagnostic agents to detect in vivo amyloid brain pathology. In addition, PET amyloid imaging will also help test the amyloid cascade hypothesis of AD and as an aid to assess the efficacy of antiamyloid therapeutics currently under development in clinical trials.

• Authors: Shankar Vallabhajosula
• Journal: Seminars in nuclear medicine (Semin Nucl Med) Vol. 41 Issue 4 Pg. 283-99 (Jul 2011) ISSN: 1558-4623 [Electronic] United States
• PMID: 21624562 (Publication Type: Journal Article, Review)
• Copyright: Copyright © 2011 Elsevier Inc. All rights reserved.

Chemical References

• 2-(1-(6-((2-fluoroethyl)(methyl)amino)-2-naphthyl)ethylidene)malononitrile
• 2-(4'-(methylamino)phenyl)-6-hydroxybenzothiazole
• APP protein, human
• Amyloid beta-Peptides
• Amyloid beta-Protein Precursor
• Aniline Compounds
• Antibodies, Monoclonal
• Antibodies, Monoclonal, Humanized
• Benzothiazoles
• Ethylene Glycols
• Nitriles
• Radiopharmaceuticals
• Thiazoles
• Fluorodeoxyglucose F18
• florbetapir
• bapineuzumab

Topics

• Alzheimer Disease (diagnostic imaging, drug therapy)
• Amyloid beta-Peptides (adverse effects, chemistry, metabolism)
• Amyloid beta-Protein Precursor (metabolism)
• Aniline Compounds (chemistry)
• Antibodies, Monoclonal (therapeutic use)
• Antibodies, Monoclonal, Humanized
• Benzothiazoles (chemistry)
• Cerebral Cortex (diagnostic imaging, metabolism, pathology)
• Dementia (diagnosis, diagnostic imaging, pathology)
• Ethylene Glycols (chemistry)
• Fluorodeoxyglucose F18 (chemistry)
• Humans
• Magnetic Resonance Imaging (methods)
• Neurofibrillary Tangles (diagnostic imaging)
• Nitriles (chemistry)
• Positron-Emission Tomography (methods)
• Radiopharmaceuticals (chemistry)
• Thiazoles