Selected Positron Emission Tomography Technologies for Evaluation of Alzheimer Disease

Alzheimer disease (AD) is a fatal neurodegenerative disease that causes progressive loss in memory, language, and thinking, with the eventual loss of ability to perform social and functional activities in daily life. Because clinical diagnosis can be difficult, particularly early in the course of the disease or with atypical dementia, there has been considerable interest in developing biomarkers for AD that can be imaged through positron emission tomography (PET). Three radioactive tracers (florbetapir fluorine 18, florbetaben fluorine 18, flutemetamol fluorine 18) that bind to amyloid beta and can be detected in vivo with PET have been approved by the U.S. Food and Drug Administration (FDA) for amyloid beta imaging in patients who are being evaluated for cognitive decline. Amyloid beta plaque PET imaging is proposed as an adjunct to the clinical diagnosis of AD and as a component of identifying patients for amyloid beta plaque-targeting therapy. Fluorine 18 fluorodeoxyglucose PET (FDG-PET) quantifies brain function by measuring glucose levels. FDG-PET is proposed as a method to distinguish AD from other dementias through identifying distinct regions of hypometabolism.