Meta-analytic comparison between PIB-PET and FDG-PET results in Alzheimer's disease and MCI.

We conducted a meta-analysis of positron emission tomography (PET) findings in Alzheimer's disease (AD) and mild cognitive impairment (MCI) to clarify the changes underpinning these conditions. All studies that utilised the PET tracers Pittsburgh Compound-B (PIB) or 2-[18F]fluoro-2-deoxy-D-glucose (FDG) to investigate patients with MCI or AD, were considered for the meta-analysis. Meta-analyses of PIB-PET and FDG-PET changes between patients and controls were undertaken with the effect-size signed differential mapping (ES-SDM) voxel-based meta-analytic method. A total of 24 studies were included involving 728 AD patients, 211 MCI patients and 658 healthy controls. Individuals with AD showed a significant PIB retention in bilateral precuneus and temporal, supramarginal, cingulate and fusiform gyri, as well as right insula and putamen. In addition, AD patients showed significant glucose hypometabolism in bilateral precuneus and temporal, supramarginal, cingulate, fusiform, angular, inferior parietal and middle frontal gyri, as well as left precentral and parahippocampal gyri and right superior frontal gyrus and thalamus. An exploratory meta-analysis of the few studies on MCI showed mildly decreased glucose metabolism with a similar regional distribution than in patients with AD. We suggest that our results can be used for further region-of-interest studies of AD and MCI patients.