title: MinR 10/20 system: Quantitative and reproducible cranial landmark setting method for MRI based on minimum initial reference points.
abstract: BACKGROUND
  The international 10/20 system is not only a fundamental method for describing positioning for electroencephalography (EEG), but also provides intermediate cranial landmarks for the probabilistic spatial registration methods that use a reference-MRI database. However, the presence of the inion, one of the four initial reference landmarks of the international 10/20 system, is inconspicuous and can be difficult to locate on MRIs.
  
  
  METHODS
  The MinR 10/20 system utilizes only three initial reference points, the nasion (Nz) and the right and left preauricular points (AR and AL), but does not employ the inion (Iz). With the MinR 10/20 system, first the most posterior point on the occipital protuberance, IIz (Imitated Iz), is identified as an exploratory alternative to the Iz point. Next, the other landmarks are calculated according to the conventional international 10/20 system referring to these four reference points (Nz, AL, AR and IIz).
  
  
  RESULTS
  Holistic tendencies for landmark position estimations on the heads and cortices in MNI space did not vary greatly between MinR and international 10/20 systems.
  
  
  METHODS
  A comparison of MinR and international 10/20 systems applied to seventeen adult head MRIs revealed little variance in holistic tendencies for landmark position estimations on head and cortex surfaces in the MNI coordinate system. Furthermore, variability was smaller with the MinR 10/20 system than with the conventional international 10/20 system.
  
  
  CONCLUSIONS
  The MinR 10/20 system proved to be a practical alternative to the conventional international 10/20 system in modern computational spatial analysis for scalp-based brain mapping methods.
authors.affiliation: Information Science and Technology Department, National Institute of Technology, Yuge College, 1000 Shimoyuge, Yuge, Kamijima-cho, Ochi-gun, Ehime 794-2593, Japan; Functional Brain Science Laboratory, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498, Japan. Electronic address: tsuzuki@jichi.ac.jp.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Tsuzuki
authors.affiliation: Graduate School of Education, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Hama
authors.initials: H
authors.lastname: Watanabe
authors.affiliation: Functional Brain Science Laboratory, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498, Japan; Department of Integrated Science and Engineering for Sustainable Society, Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan; Applied Cognitive Neuroscience Laboratory, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan.
authors.forename: Ippeita
authors.initials: I
authors.lastname: Dan
authors.affiliation: Graduate School of Education, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Gentaro
authors.initials: G
authors.lastname: Taga
mesh_terms: D000328:Adult; D004569:Electroencephalography / Q000379:methods / Q000592:standards*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods / Q000592:standards*; D059906:Neuroimaging / Q000379:methods / Q000592:standards*; D012886:Skull / Q000033:anatomy & histology*
keywords: Cranial landmark setting; Head positions; Human brain mapping; Inter-modal data sharing; International 10/20 system; MRI