title: Detecting hippocampal hypometabolism in Mild Cognitive Impairment using automatic voxel-based approaches.
abstract: While the hippocampus is constantly reported as the site of earliest and highest structural alteration in Alzheimer's disease (AD), findings regarding the metabolic status of this region are rather heterogeneous. It has been proposed that only a time-consuming individual region-of-interest (ROI) approach would allow the detection of hypometabolism in this complex and small area. Our main goal with this study is to assess whether more automatic and clinically useful methods would be sensitive enough when considering other methodological confounds. From a single PET data set collected in 28 patients with amnestic Mild Cognitive Impairment (aMCI) and 19 controls, we assessed the effects of partial volume effect (PVE) correction, scaling (using vermis or global means), and analysis method (individual ROI versus more automatic template-based ROI or voxel-based approaches) on hippocampal hypometabolism detection in aMCI. PVE correction and scaling both showed a significant effect on group comparison, while the analysis method (individual versus template-based ROI) surprisingly did not. Hippocampal metabolic decrease was significant in all vermis-scaled conditions, and more so after PVE correction. Our findings highlight the crucial relevance of using reference-region-based (instead of global) scaling, and the higher sensitivity of PVE-corrected PET measures, to detect hippocampal hypometabolism in aMCI. They also show that hippocampal metabolic decline can be detected using template-based ROI as well as voxel-based methods. These findings have clinical relevance since they support the validity of more automatic and time-saving approaches to assess hippocampal metabolism changes in aMCI and early AD.
authors.affiliation: Inserm E0218-EPHE-Université de Caen Basse-Normandie, Laboratoire de Neuropsychologie, GIP Cyceron, CHU Côte de Nacre, Bd H Becquerel, 14074 Caen cedex, Caen, France.
authors.forename: Katell
authors.initials: K
authors.lastname: Mevel
authors.forename: Béatrice
authors.initials: B
authors.lastname: Desgranges
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Baron
authors.forename: Brigitte
authors.initials: B
authors.lastname: Landeau
authors.forename: Vincent
authors.initials: V
authors.lastname: De la Sayette
authors.forename: Fausto
authors.initials: F
authors.lastname: Viader
authors.forename: Francis
authors.initials: F
authors.lastname: Eustache
authors.forename: Gaël
authors.initials: G
authors.lastname: Chételat
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000000981:diagnostic imaging / Q000503:physiopathology; D000647:Amnesia / Q000000981:diagnostic imaging / Q000503:physiopathology*; D002421:Caudate Nucleus / Q000000981:diagnostic imaging / Q000503:physiopathology; D003072:Cognition Disorders / Q000000981:diagnostic imaging / Q000503:physiopathology*; D004292:Dominance, Cerebral / Q000502:physiology; D005260:Female; D006179:Gyrus Cinguli / Q000000981:diagnostic imaging / Q000503:physiopathology; D006624:Hippocampus / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D012016:Reference Values; D012680:Sensitivity and Specificity; D012984:Software; D013787:Thalamic Nuclei / Q000000981:diagnostic imaging / Q000503:physiopathology