title: Comparison between PET template-based method and MRI-based method for cortical quantification of florbetapir (AV-45) uptake in vivo.
abstract: OBJECTIVE
  Florbetapir (AV-45) has been shown to be a reliable tool for assessing in vivo amyloid load in patients with Alzheimer's disease from the early stages. However, nonspecific white matter binding has been reported in healthy subjects as well as in patients with Alzheimer's disease. To avoid this issue, cortical quantification might increase the reliability of AV-45 PET analyses. In this study, we compared two quantification methods for AV-45 binding, a classical method relying on PET template registration (route 1), and a MRI-based method (route 2) for cortical quantification.
  
  
  METHODS
  We recruited 22 patients at the prodromal stage of Alzheimer's disease and 17 matched controls. AV-45 binding was assessed using both methods, and target-to-cerebellum mean global standard uptake values (SUVr) were obtained for each of them, together with SUVr in specific regions of interest. Quantification using the two routes was compared between the clinical groups (intragroup comparison), and between groups for each route (intergroup comparison). Discriminant analysis was performed.
  
  
  RESULTS
  In the intragroup comparison, differences in uptake values were observed between route 1 and route 2 in both groups. In the intergroup comparison, AV-45 uptake was higher in patients than controls in all regions of interest using both methods, but the effect size of this difference was larger using route 2. In the discriminant analysis, route 2 showed a higher specificity (94.1 % versus 70.6 %), despite a lower sensitivity (77.3 % versus 86.4 %), and D-prime values were higher for route 2.
  
  
  CONCLUSIONS
  These findings suggest that, although both quantification methods enabled patients at early stages of Alzheimer's disease to be well discriminated from controls, PET template-based quantification seems adequate for clinical use, while the MRI-based cortical quantification method led to greater intergroup differences and may be more suitable for use in current clinical research.
authors.affiliation: Inserm, imagerie cérébrale et handicaps neurologiques UMR 825, Centre Hospitalier Universitaire de Toulouse, Pavillon Baudot CHU Purpan lace Dr Baylac, 31059, Toulouse, France, laure.saint-aubert@inserm.fr.
authors.forename: L
authors.initials: L
authors.lastname: Saint-Aubert
authors.forename: F
authors.initials: F
authors.lastname: Nemmi
authors.forename: P
authors.initials: P
authors.lastname: Péran
authors.forename: E J
authors.initials: EJ
authors.lastname: Barbeau
authors.forename: P
authors.initials: P
authors.lastname: Payoux
authors.forename: F
authors.initials: F
authors.lastname: Chollet
authors.forename: J
authors.initials: J
authors.lastname: Pariente
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000175:diagnosis / Q000000981:diagnostic imaging*; D000814:Aniline Compounds; D016022:Case-Control Studies; D002540:Cerebral Cortex / Q000000981:diagnostic imaging; D005026:Ethylene Glycols; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging; D008297:Male; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals
chemical_list: D000814:Aniline Compounds; D005026:Ethylene Glycols; D019275:Radiopharmaceuticals; C545186:florbetapir