This multicenter study examined 18F-FDG PET measures in the differential diagnosis of Alzheimer’s disease (AD), frontotemporal dementia (FTD), and dementia with Lewy bodies (DLB) from normal aging and from each other and the relation of disease-specific patterns to mild cognitive impairment (MCI).
We examined the 18F-FDG PET scans of 548 subjects, including 110 healthy elderly individuals (“normals” or NLs), 114 MCI, 199 AD,98FTD, and 27 DLB patients, collected at 7 participating centers. Individual PET scans were Z scored using automated voxel-based comparison with generation of disease-specific patterns of cortical and hippocampal 18F-FDG uptake that were then applied to characterize MCI.
Standardized disease-specific PET patterns were developed that correctly classified 95%AD, 92% DLB,94%FTD,and 94%NL. MCI patients showed primarily posterior cingulate cortex and hippocampal hypometabolism (81%), whereas neocortical abnormalities varied according to neuropsychological profiles. An AD PET pattern was observed in 79% MCI with deficits in multiple cognitive domains and 31% amnesic MCI. 18F-FDG PET heterogeneity in MCI with nonmemory deficits ranged from absent hypometabolism to FTD and DLB PET patterns.
Standardized automated analysis of 18F-FDG PET scans may provide an objective and sensitive support to the clinical diagnosis in early dementia.