MAPT and Alzheimer disease: The objective of this work was therefore to evaluate tau deposition using 18F-PI-2620 PET in amyloid-beta positive subjects with a diagnosis of mild cognitive impairment (MCI) due to AD or mild AD dementia and characterize it with respect to amyloid-beta deposition, CSF (amyloid-beta, t-tau, p-tau), hippocampal volume, and several neurocognitive domains from a series of cognitive instruments.