title: Inter-rater variability of visual interpretation and comparison with quantitative evaluation of11C-PiB PET amyloid images of the Japanese Alzheimer's Disease Neuroimaging Initiative (J-ADNI) multicenter study.
abstract: OBJECTIVE
  The aim of this study was to assess the inter-rater variability of the visual interpretation of11C-PiB PET images regarding the positivity/negativity of amyloid deposition that were obtained in a multicenter clinical research project, Japanese Alzheimer's Disease Neuroimaging Initiative (J-ADNI). The results of visual interpretation were also compared with a semi-automatic quantitative analysis using mean cortical standardized uptake value ratio to the cerebellar cortex (mcSUVR).
  
  
  METHODS
  A total of 16211C-PiB PET scans, including 45 mild Alzheimer's disease, 60 mild cognitive impairment, and 57 normal cognitive control cases that had been acquired as J-ADNI baseline scans were analyzed. Based on visual interpretation by three independent raters followed by consensus read, each case was classified into positive, equivocal, and negative deposition (ternary criteria) and further dichotomized by merging the former two (binary criteria).
  
  
  RESULTS
  Complete agreement of visual interpretation by the three raters was observed for 91.3% of the cases (Cohen κ = 0.88 on average) in ternary criteria and for 92.3% (κ = 0.89) in binary criteria. Cases that were interpreted as visually positive in the consensus read showed significantly higher mcSUVR than those visually negative (2.21 ± 0.37 vs. 1.27 ± 0.09, p < 0.001), and positive or negative decision by visual interpretation was dichotomized by a cut-off value of mcSUVR = 1.5. Significant positive/negative associations were observed between mcSUVR and the number of raters who evaluated as positive (ρ = 0.87, p < 0.0001) and negative (ρ = -0.85, p < 0.0001) interpretation. Cases of disagreement among raters showed generally low mcSUVR.
  
  
  CONCLUSIONS
  Inter-rater agreement was almost perfect in11C-PiB PET scans. Positive or negative decision by visual interpretation was dichotomized by a cut-off value of mcSUVR = 1.5. As some cases of disagreement among raters tended to show low mcSUVR, referring to quantitative method may facilitate correct diagnosis when evaluating images of low amyloid deposition.
authors.affiliation: Department of Nuclear Medicine, Saitama Medical University Saitama International Center, 1397-1 Yamane, Hidaka, 350-1298, Japan. yamane_t@saitama-med.ac.jp.|Division of Molecular Imaging, Institute of Biomedical Research and Innovation, 2-2 Minatojima-Minamimachi, Chuo-ku, Kobe, 650-0047, Japan. yamane_t@saitama-med.ac.jp.|Team for Neuroimaging Research, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakaecho, Itabashi-ku, Tokyo, 173-0015, Japan. yamane_t@saitama-med.ac.jp.|, . yamane_t@saitama-med.ac.jp.
authors.forename: Tomohiko
authors.identifier: http://orcid.org/0000-0003-0955-4272
authors.initials: T
authors.lastname: Yamane
authors.affiliation: Team for Neuroimaging Research, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakaecho, Itabashi-ku, Tokyo, 173-0015, Japan.|.
authors.forename: Kenji
authors.initials: K
authors.lastname: Ishii
authors.affiliation: Team for Neuroimaging Research, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakaecho, Itabashi-ku, Tokyo, 173-0015, Japan.|.
authors.forename: Muneyuki
authors.initials: M
authors.lastname: Sakata
authors.affiliation: Division of Molecular Imaging, Institute of Biomedical Research and Innovation, 2-2 Minatojima-Minamimachi, Chuo-ku, Kobe, 650-0047, Japan.|.|Research Association for Biotechnology, 1-7-1 Misuji, Taito-ku, Tokyo, 111-0055, Japan.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Ikari
authors.affiliation: Division of Molecular Imaging, Institute of Biomedical Research and Innovation, 2-2 Minatojima-Minamimachi, Chuo-ku, Kobe, 650-0047, Japan.|.|Research Association for Biotechnology, 1-7-1 Misuji, Taito-ku, Tokyo, 111-0055, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Nishio
authors.affiliation: .|Department of Radiology, Kinki University Hospital, 377-2 Onohigashi, Osaka, Sayama, 589-8511, Japan.
authors.forename: Kazunari
authors.initials: K
authors.lastname: Ishii
authors.affiliation: .|Department of Brain Science and Molecular Imaging, National Center for Geriatrics and Gerontology, 7-430 Morioka-machi, Obu, 474-8511, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kato
authors.affiliation: .|Department of Brain Science and Molecular Imaging, National Center for Geriatrics and Gerontology, 7-430 Morioka-machi, Obu, 474-8511, Japan.
authors.forename: Kengo
authors.initials: K
authors.lastname: Ito
authors.affiliation: Division of Molecular Imaging, Institute of Biomedical Research and Innovation, 2-2 Minatojima-Minamimachi, Chuo-ku, Kobe, 650-0047, Japan.|.
authors.forename: Michio
authors.initials: M
authors.lastname: Senda
mesh_terms: D000544:Alzheimer Disease / Q000000981:diagnostic imaging*; D000814:Aniline Compounds; D052160:Benzothiazoles; D032921:Consensus; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D059906:Neuroimaging; D015588:Observer Variation; D049268:Positron-Emission Tomography; D013844:Thiazoles
chemical_list: C475519:2-(4'-(methylamino)phenyl)-6-hydroxybenzothiazole; D000814:Aniline Compounds; D052160:Benzothiazoles; D013844:Thiazoles
keywords: 11C-PiB PET; Amyloid imaging; Inter-rater variability; Mean cortical SUVR; Multi-center study