title: Amyloid PET in European and North American cohorts; and exploring age as a limit to clinical use of amyloid imaging.
abstract: OBJECTIVE
  Several radiotracers that bind to fibrillar amyloid-beta in the brain have been developed and used in various patient cohorts. This study aimed to investigate the comparability of two amyloid positron emission tomography (PET) tracers as well as examine how age affects the discriminative properties of amyloid PET imaging.
  
  
  METHODS
  Fifty-one healthy controls (HCs), 72 patients with mild cognitive impairment (MCI) and 90 patients with Alzheimer's disease (AD) from a European cohort were scanned with [11C]Pittsburgh compound-B (PIB) and compared with an age-, sex- and disease severity-matched population of 51 HC, 72 MCI and 84 AD patients from a North American cohort who were scanned with [18F]Florbetapir. An additional North American population of 246 HC, 342 MCI and 138 AD patients with a Florbetapir scan was split by age (55-75 vs 76-93 y) into groups matched for gender and disease severity. PET template-based analyses were used to quantify regional tracer uptake.
  
  
  RESULTS
  The mean regional uptake patterns were similar and strong correlations were found between the two tracers across the regions of interest in HC (ρ = 0.671, p = 0.02), amyloid-positive MCI (ρ = 0.902, p < 0.001) and AD patients (ρ = 0.853, p < 0.001). The application of the Florbetapir cut-off point resulted in a higher proportion of amyloid-positive HC and a lower proportion of amyloid-positive AD patients in the older group (28 and 30 %, respectively) than in the younger group (19 and 20 %, respectively).
  
  
  CONCLUSIONS
  These results illustrate the comparability of Florbetapir and PIB in unrelated but matched patient populations. The role of amyloid PET imaging becomes increasingly important with increasing age in the diagnostic assessment of clinically impaired patients.
authors.affiliation: Department of NVS, Center for Alzheimer Research, Translational Alzheimer Neurobiology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Chiotis
authors.forename: Stephen F
authors.initials: SF
authors.lastname: Carter
authors.forename: Karim
authors.initials: K
authors.lastname: Farid
authors.forename: Irina
authors.initials: I
authors.lastname: Savitcheva
authors.forename: Agneta
authors.initials: A
authors.lastname: Nordberg
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000378:metabolism*; D000544:Alzheimer Disease / Q000000981:diagnostic imaging / Q000378:metabolism*; D016229:Amyloid beta-Peptides / Q000378:metabolism; D000814:Aniline Compounds / Q000493:pharmacokinetics*; D015415:Biomarkers / Q000378:metabolism; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism; D060825:Cognitive Dysfunction / Q000000981:diagnostic imaging / Q000378:metabolism*; D015331:Cohort Studies; D005026:Ethylene Glycols / Q000493:pharmacokinetics*; D005060:Europe; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D057054:Molecular Imaging / Q000379:methods*; D009656:North America; D049268:Positron-Emission Tomography / Q000379:methods; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012727:Sex Characteristics; D013844:Thiazoles / Q000493:pharmacokinetics*
chemical_list: C475519:2-(4'-(methylamino)phenyl)-6-hydroxybenzothiazole; D016229:Amyloid beta-Peptides; D000814:Aniline Compounds; D015415:Biomarkers; D005026:Ethylene Glycols; D019275:Radiopharmaceuticals; D013844:Thiazoles; C545186:florbetapir