title: Simultaneous PET-MRI Studies of the Concordance of Atrophy and Hypometabolism in Syndromic Variants of Alzheimer's Disease and Frontotemporal Dementia: An Extended Case Series.
abstract: BACKGROUND
  Simultaneous PET-MRI is used to compare patterns of cerebral hypometabolism and atrophy in six different dementia syndromes.
  
  
  OBJECTIVE
  The primary objective was to conduct an initial exploratory study regarding the concordance of atrophy and hypometabolism in syndromic variants of Alzheimer's disease (AD) and frontotemporal dementia (FTD). The secondary objective was to determine the effect of image analysis methods on determination of atrophy and hypometabolism.
  
  
  METHODS
  PET and MRI data were acquired simultaneously on 24 subjects with six variants of AD and FTD (n = 4 per group). Atrophy was rated visually and also quantified with measures of cortical thickness. Hypometabolism was rated visually and also quantified using atlas- and SPM-based approaches. Concordance was measured using weighted Cohen's kappa.
  
  
  RESULTS
  Atrophy-hypometabolism concordance differed markedly between patient groups; kappa scores ranged from 0.13 (nonfluent/agrammatic variant of primary progressive aphasia, nfvPPA) to 0.49 (posterior cortical variant of AD, PCA). Heterogeneity was also observed within groups; the confidence intervals of kappa scores ranging from 0-0.25 for PCA to 0.29-0.61 for nfvPPA. More widespread MRI and PET changes were identified using quantitative methods than on visual rating.
  
  
  CONCLUSIONS
  The marked differences in concordance identified in this initial study may reflect differences in the molecular pathologies underlying AD and FTD syndromic variants but also operational differences in the methods used to diagnose these syndromes. The superior ability of quantitative methodologies to detect changes on PET and MRI, if confirmed on larger cohorts, may favor their usage over qualitative visual inspection in future clinical diagnostic practice.
authors.affiliation: Brighton and Sussex Medical School, Falmer, UK.
authors.forename: Kuven K
authors.initials: KK
authors.lastname: Moodley
authors.affiliation: Vita-Salute San Raffaele University, Nuclear Medicine Unit San Raffaele Hospital, Division of Neuroscience IRCCS San Raffaele, Milano, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Perani
authors.affiliation: Brighton and Sussex Medical School, Falmer, UK.|Scientific Department, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy.
authors.forename: Ludovico
authors.initials: L
authors.lastname: Minati
authors.affiliation: Institute of Molecular Bio-imaging and Physiology, National Research Council, Milano, Italy.
authors.forename: Pasquale Anthony
authors.initials: PA
authors.lastname: Della Rosa
authors.affiliation: OpenUniversity, Milton Keynes, UK.
authors.forename: Frank
authors.initials: F
authors.lastname: Pennycook
authors.affiliation: Institute of Nuclear Medicine, University College London, London, UK.
authors.forename: John C
authors.initials: JC
authors.lastname: Dickson
authors.affiliation: Institute of Nuclear Medicine, University College London, London, UK.
authors.forename: Anna
authors.initials: A
authors.lastname: Barnes
authors.affiliation: Neuroradiology Department, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy.
authors.forename: Valeria Elisa
authors.initials: VE
authors.lastname: Contarino
authors.affiliation: Institute of Nuclear Medicine, University College London, London, UK.
authors.forename: Sofia
authors.initials: S
authors.lastname: Michopoulou
authors.affiliation: Neuroradiology Department, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy.
authors.forename: Ludovico
authors.initials: L
authors.lastname: D'Incerti
authors.affiliation: Hurstwood Park Neurosciences Centre, West Sussex, UK.
authors.forename: Catriona
authors.initials: C
authors.lastname: Good
authors.affiliation: Vita-Salute San Raffaele University, Nuclear Medicine Unit San Raffaele Hospital, Division of Neuroscience IRCCS San Raffaele, Milano, Italy.
authors.forename: Federico
authors.initials: F
authors.lastname: Fallanca
authors.affiliation: Vita-Salute San Raffaele University, Nuclear Medicine Unit San Raffaele Hospital, Division of Neuroscience IRCCS San Raffaele, Milano, Italy.
authors.forename: Emilia Giovanna
authors.initials: EG
authors.lastname: Vanoli
authors.affiliation: Institute of Nuclear Medicine, University College London, London, UK.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Ell
authors.affiliation: Brighton and Sussex Medical School, Falmer, UK.
authors.forename: Dennis
authors.initials: D
authors.lastname: Chan
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000000981:diagnostic imaging / Q000473:pathology*; D001284:Atrophy; D001921:Brain / Q000000981:diagnostic imaging* / Q000473:pathology*; D001931:Brain Mapping; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism; D057180:Frontotemporal Dementia / Q000000981:diagnostic imaging / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D011569:Psychiatric Status Rating Scales; D015203:Reproducibility of Results
chemical_list: D019788:Fluorodeoxyglucose F18
keywords: Alzheimer’s disease; NEUROSTAT; atrophy; frontotemporal dementia; hypometabolism; simultaneous PET-MRI; statistical parametric mapping; visual rating