title: Comparison of the binding characteristics of [18F]THK-523 and other amyloid imaging tracers to Alzheimer's disease pathology.
abstract: OBJECTIVE
  Extensive deposition of senile plaques and neurofibrillary tangles in the brain is a pathological hallmark of Alzheimer's disease (AD). Although several PET imaging agents have been developed for in vivo detection of senile plaques, no PET probe is currently available for selective detection of neurofibrillary tangles in the living human brain. Recently, [(18)F]THK-523 was developed as a potential in vivo imaging probe for tau pathology. The purpose of this study was to compare the binding properties of [(18)F]THK-523 and other amyloid imaging agents, including PiB, BF-227 and FDDNP, to synthetic protein fibrils and human brain tissue.
  
  
  METHODS
  In vitro radioligand binding assays were conducted using synthetic amyloid β(42) and K18ΔK280-tau fibrils. Nonspecific binding was determined by the addition of unlabelled compounds at a concentration of 2 μM. To examine radioligand binding to neuropathological lesions, in vitro autoradiography was conducted using sections of AD brain.
  
  
  RESULTS
  [(18)F]THK-523 showed higher affinity for tau fibrils than for Aβ fibrils, whereas the other probes showed a higher affinity for Aβ fibrils. The autoradiographic analysis indicated that [(18)F]THK-523 accumulated in the regions containing a high density of tau protein deposits. Conversely, PiB and BF-227 accumulated in the regions containing a high density of Aβ plaques.
  
  
  CONCLUSIONS
  These findings suggest that the unique binding profile of [(18)F]THK-523 can be used to identify tau deposits in AD brain.
authors.affiliation: Department of Pharmacology, Tohoku University School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Japan.
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Harada
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Okamura
authors.forename: Shozo
authors.initials: S
authors.lastname: Furumoto
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Tago
authors.forename: Masahiro
authors.initials: M
authors.lastname: Maruyama
authors.forename: Makoto
authors.initials: M
authors.lastname: Higuchi
authors.forename: Takeo
authors.initials: T
authors.lastname: Yoshikawa
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Arai
authors.forename: Ren
authors.initials: R
authors.lastname: Iwata
authors.forename: Yukitsuka
authors.initials: Y
authors.lastname: Kudo
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Yanai
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000000981:diagnostic imaging*; D000682:Amyloid / Q000032:analysis* / Q000378:metabolism; D000814:Aniline Compounds / Q000378:metabolism*; D001921:Brain / Q000000981:diagnostic imaging; D001923:Brain Chemistry; D006801:Humans; D049268:Positron-Emission Tomography; D011485:Protein Binding; D011804:Quinolines / Q000378:metabolism*; D011849:Radioactive Tracers; D011869:Radioligand Assay; D019275:Radiopharmaceuticals / Q000378:metabolism*
chemical_list: C559040:2-(4-aminophenyl)-6-(2-fluoroethoxy)quinoline; D000682:Amyloid; D000814:Aniline Compounds; D011804:Quinolines; D011849:Radioactive Tracers; D019275:Radiopharmaceuticals