A method for labeling structures, such as .beta.-amyloid plaques and neurofibrillary tangles, in vivo or in vitro, is provided and comprises contacting brain tissue with one or more compounds, preferably radiolabeled for detection by positron emission tomography (PET).
ACKNOWLEDGMENT OF GOVERNMENT SUPPORT
 This invention was made with government support under Grant No. DE-FC0387-ER60615, awarded by the United States Department of Energy. The government has certain rights in the invention.