Multicenter Standardized ¹⁸F-FDG PET Diagnosis of Mild Cognitive Impairment, Alzheimer's Disease, and Other Dementias

TLDR

In mild cognitive impairment with non‑memory deficits, ^18F‑FDG PET shows heterogeneous patterns ranging from absent hypometabolism to FTD and DLB signatures, suggesting that standardized automated analysis could aid early dementia diagnosis. The study aimed to evaluate ^18F‑FDG PET for distinguishing AD, FTD, DLB, and normal aging, and to relate disease‑specific patterns to MCI. Using automated voxel‑based Z‑scoring of PET scans from 548 subjects across seven centers, the authors generated disease‑specific cortical and hippocampal uptake patterns to classify MCI. The patterns achieved 95 % accuracy for AD, 92 % for DLB, 94 % for FTD, and 94 % for normal controls, and revealed that 81 % of MCI patients exhibited posterior cingulate and hippocampal hypometabolism, with 79 % showing an AD‑like pattern and 31 % amnesic MCI.

Abstract

This multicenter study examined (18)F-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 (18)F-FDG PET scans of 548 subjects, including 110 healthy elderly individuals ("normals" or NLs), 114 MCI, 199 AD, 98 FTD, 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 (18)F-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. (18)F-FDG PET heterogeneity in MCI with nonmemory deficits ranged from absent hypometabolism to FTD and DLB PET patterns.Standardized automated analysis of (18)F-FDG PET scans may provide an objective and sensitive support to the clinical diagnosis in early dementia.