Reduced hippocampal metabolism in MCI and AD: automated FDG-PET image analysis

University of Florence, Florens, Tuscany, Italy
Neurology (Impact Factor: 8.29). 07/2005; 64(11):1860-7. DOI: 10.1212/01.WNL.0000163856.13524.08
Source: PubMed


To facilitate image analysis, most recent 2-[18F]fluoro-2-deoxy-d-glucose PET (FDG-PET) studies of glucose metabolism (MRglc) have used automated voxel-based analysis (VBA) procedures but paradoxically none reports hippocampus MRglc reductions in mild cognitive impairment (MCI) or Alzheimer disease (AD). Only a few studies, those using regions of interest (ROIs), report hippocampal reductions. The authors created an automated and anatomically valid mask technique to sample the hippocampus on PET (HipMask).
Hippocampal ROIs drawn on the MRI of 48 subjects (20 healthy elderly [NL], 16 MCI, and 12 AD) were used to develop the HipMask. The HipMask technique was applied in an FDG-PET study of NL (n = 11), MCI (n = 13), and AD (n = 12), and compared to both MRI-guided ROIs and VBA methods.
HipMask and ROI hippocampal sampling produced significant and equivalent MRglc reductions for contrasts between MCI and AD relative to NL. The VBA showed typical cortical effects but failed to show hippocampal MRglc reductions in either clinical group. Hippocampal MRglc was the only discriminator of NL vs MCI (78% accuracy) and added to the cortical MRglc in classifying NL vs AD and MCI vs AD.
The new HipMask technique provides accurate and rapid assessment of the hippocampus on PET without the use of regions of interest. Hippocampal glucose metabolism reductions are found in both mild cognitive impairment and Alzheimer disease and contribute to their diagnostic classification. These results suggest re-examination of prior voxel-based analysis 2-[18F]fluoro-2-deoxy-d-glucose PET studies that failed to report hippocampal effects.

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    • "ADNI FDG-PET subset. An additional FDG-PET ADNI subset was defined by selecting the subjects in the " complete annual year 2 visits " 1.5T standardized ADNI dataset that had an associated baseline FDG-PET measurement of hippocampus metabolic rate of glucose available from the Center for Brain Health, NYU School of Medicine , New York [Li et al., 2008; Mosconi et al., 2005]. We further required a maximum of 60 days between MRI and FDG-PET scans, which resulted in a total of 215 subjects (Table I). "
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    • "campus through the perforant pathway ( Van Hoesen and Pandya , 1975 ) . CA3 neurons project Schaffer collaterals to CA1 pyramidal neurons , which finally project to the subiculum and deep EC layers IV , V and VI ( EC - IV - VI ; Figure 1 ) . The MTL undergoes atrophy and hypometabolism not only in AD but also in MCI stages ( Press et al . , 1989 ; Mosconi et al . , 2005 ; La Joie et al . , 2013 ) , an effect observed at least 4 years in advance to cognitive symptoms ( Tondelli et al . , 2012 ) . Indeed , disruption of the hippocampus , a critical component of this memory circuit , is sufficient to produce anterograde amnesia ( Zola - Morgan et al . , 1986 ) . The EC is severely affected by pathological"
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    • "Numerous epidemiologic studies have shown that diabetes and insulin resistance are strong risk factors for cognitive decline and AD [55] [56] [57] [58] [59] [60], and we and others have shown that impaired glucose metabolism is associated with increased progression from mild cognitive impairment to AD [61] [62]. Moreover, clinical studies using FDG-PET have demonstrated that decreased glucose metabolism occurs very early in AD brain and is predictive of disease diagnosis [63] [64]. "
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