title: Head-to-head comparison of 11C-PiB and 18F-AZD4694 (NAV4694) for β-amyloid imaging in aging and dementia.
abstract: (11)C-Pittsburgh compound-B ((11)C-PiB) is the benchmark radiotracer for imaging of β-amyloid (Aβ) plaque in Alzheimer disease (AD). (18)F-labeled Aβ tracers subsequently developed for clinical use show higher nonspecific white matter binding and, in some cases, lower cortical binding in AD that could lead to less accurate interpretation of scans. We compared the cortical and white matter binding of a new (18)F-labeled Aβ tracer, (18)F-AZD4694 (recently renamed NAV4694), with (11)C-PiB in the same subjects.
  
  
  METHODS
  Forty-five participants underwent PET imaging with (11)C-PiB and (18)F-AZD4694 (25 healthy elderly controls [HCs], 10 subjects with mild cognitive impairment, 7 subjects with probable AD, and 3 subjects with probable frontotemporal dementia). Images were coregistered so that region-of-interest placement was identical on both scans, and standardized uptake value ratios (SUVRs) using the cerebellar cortex as a reference region were calculated between 40 and 70 min after injection for both tracers.
  
  
  RESULTS
  (18)F-AZD4694 showed reversible binding kinetics similar to (11)C-PiB, reaching an apparent steady state at 50 min after injection. Both radiotracers showed a similar dynamic range of neocortical SUVR (1.1-3.3 and 1.0-3.2 SUVR for (11)C-PiB and (18)F-AZD4694, respectively) and identical low nonspecific white matter binding, with frontal cortex-to-white matter ratios of 0.7 ± 0.2 and 1.3 ± 0.2 for both radiotracers in HCs and AD subjects, respectively. There was an excellent linear correlation between (11)C-PiB and (18)F-AZD4694 neocortical SUVR (slope of 0.95, r = 0.99, P < 0.0001).
  
  
  CONCLUSIONS
  (18)F-AZD4694 displays imaging characteristics nearly identical to those of (11)C-PiB. The low white matter and high cortical binding in AD indicate that this tracer is well suited to both clinical and research use.
authors.affiliation: Department of Nuclear Medicine and Centre for PET, Austin Health, Heidelberg, Victoria, Australia. christopher.rowe@austin.org.au
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Rowe
authors.forename: Svetlana
authors.initials: S
authors.lastname: Pejoska
authors.forename: Rachel S
authors.initials: RS
authors.lastname: Mulligan
authors.forename: Gareth
authors.initials: G
authors.lastname: Jones
authors.forename: J Gordon
authors.initials: JG
authors.lastname: Chan
authors.forename: Samuel
authors.initials: S
authors.lastname: Svensson
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Cselényi
authors.forename: Colin L
authors.initials: CL
authors.lastname: Masters
authors.forename: Victor L
authors.initials: VL
authors.lastname: Villemagne
mesh_terms: D000368:Aged; D000375:Aging / Q000378:metabolism*; D016229:Amyloid beta-Peptides / Q000378:metabolism*; D000814:Aniline Compounds; D001572:Benzofurans / Q000378:metabolism; D052160:Benzothiazoles / Q000378:metabolism; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism; D003704:Dementia / Q000000981:diagnostic imaging / Q000378:metabolism*; D005260:Female; D006801:Humans; D006845:Hydrocarbons, Fluorinated / Q000378:metabolism; D008297:Male; D057054:Molecular Imaging / Q000379:methods*; D049268:Positron-Emission Tomography; D013844:Thiazoles
chemical_list: C475519:2-(4'-(methylamino)phenyl)-6-hydroxybenzothiazole; C552498:AZD4694; D016229:Amyloid beta-Peptides; D000814:Aniline Compounds; D001572:Benzofurans; D052160:Benzothiazoles; D006845:Hydrocarbons, Fluorinated; D013844:Thiazoles
keywords: Alzheimer’s disease; Aβ; amyloid imaging; positron emission tomography