title: Mapping brain morphological and functional conversion patterns in amnestic MCI: a voxel-based MRI and FDG-PET study.
abstract: OBJECTIVE
  To reveal the morphological and functional substrates of memory impairment and conversion to Alzheimer disease (AD) from the stage of amnestic mild cognitive impairment (aMCI).
  
  
  METHODS
  Brain MRI and FDG-PET were performed in 20 patients with aMCI and 12 controls at baseline. During a mean follow-up of about 2 years, 9 patients developed AD (converters), and 11 did not (nonconverters). All images were processed with SPM2. FDG-PET and segmented grey matter (GM) images were compared in: (1) converters versus controls, (2) nonconverters versus controls, and (3) converters versus nonconverters.
  
  
  RESULTS
  As compared to controls, converters showed lower GM density in the left parahippocampal gyrus and both thalami, and hypometabolism in the precuneus, posterior cingulate and superior parietal lobule in the left hemisphere. Hypometabolism was found in nonconverters as compared to controls in the left precuneus and posterior cingulated gyrus. As compared to nonconverters, converters showed significant hypometabolism in the left middle and superior temporal gyri.
  
  
  CONCLUSIONS
  The discordant topography between atrophy and hypometabolism reported in AD is already present at the aMCI stage. Posterior cingulate-precuneus hypometabolism seemed to be an early sign of memory deficit, whereas hypometabolism in the left temporal cortex marked the conversion to AD.
authors: Nuclear Medicine Unit, Department of Internal Medicine, University of Genoa, Viale Benedetto XV, 6, 16132 Genoa, Italy. silviadaniela.morbelli@hsanmartino.it
authors: Silvia
authors: S
authors: Morbelli
authors: Arnoldo
authors: A
authors: Piccardo
authors: Giampiero
authors: G
authors: Villavecchia
authors: Barbara
authors: B
authors: Dessi
authors: Andrea
authors: A
authors: Brugnolo
authors: Alessandra
authors: A
authors: Piccini
authors: Anna
authors: A
authors: Caroli
authors: Giovanni
authors: G
authors: Frisoni
authors: Guido
authors: G
authors: Rodriguez
authors: Flavio
authors: F
authors: Nobili
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000647:Amnesia / Q000150:complications* / Q000175:diagnosis*; D001921:Brain / Q000473:pathology*; D001931:Brain Mapping / Q000379:methods; D003072:Cognition Disorders / Q000150:complications* / Q000175:diagnosis*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18