Amyloid imaging in Alzheimer's disease

Purpose of review This paper reviews the progress in developing amyloid imaging ligands to be used to measure amyloid in vivo in the brain of patients with Alzheimer's disease. Recent findings Four radioligands, [F-18] 1,1-dicyano-2-[6-(dimethylamino)2-naphtalenyl] propene or F-18-FDDNP, N-methyl [11C] 2-(4'-methylaminophenyl)-6-hydroxy-benzothiasole or C-11-PIB, 4-N-methylamino-4'-hydroxystilbene [C-11] or SB13 and 2-(2-[2-dimethylaminothiazol-5-yllethenyl)-6(2-[fluoro]ethoxy)benzoxazole or C-11-BF-227, have so far been studied in Alzheimer's disease patients and age-matched healthy controls by PET. A robust difference was observed between PIB retention in mild patients and controls. A 2-year follow-up study in mild patients showed a stable level of PIB retention and a decrease in cerebral glucose metabolism and cognition. 18F-FDDNP showed less difference between Alzheimer's disease patients and controls compared with PIB. Both ligands have detected increases in amyloid in the brain of patients with mild cognitive impairment. Summary The new PET amyloid imaging technique is a breakthrough in understanding the pathophysiological mechanisms and time course in amyloid deposits in the brain. The technique will enable early detection of Alzheimer's disease. PET amyloid imaging should be used in the evaluation of new the antiamyloid therapies.