title: [Evaluation of optimal threshold of Z score map for statistical brain image analysis].
abstract: OBJECTIVE
  Aim of this study was to investigate optimal threshold of Z score when evaluating statistics image of Alzheimer's disease visually.
  
  
  METHODS
  We classified 53 clinical patients in control and target group, and evaluated the distribution of Z score calculated with statistical brain image analysis for magnetic resonance and perfusion single photon emission computed tomography (SPECT). The optimal Z score threshold was determined from statistical significance that compared previously mentioned groups.
  
  
  RESULTS
  Target group was able to classify significantly Z score at 1.25 from control group in wide region of parietal lobe with statistical brain image analysis for perfusion SPECT.
  
  
  CONCLUSIONS
  The optimal threshold is equal or less than 2.0, in the case of Z score variance is close to the standard normal distribution. In contrast, the threshold is over 2.0 in the case of Z score variance is more than 1.0, and then by using ordinary threshold 2.0, it cannot point out abnormality.
authors.affiliation: 1. Department of Radiology, Kyushu Rosai Hospital, Japan Labor Health and Welfare Organization; 2. Program in Health and Welfare Graduate School of Comprehensive Scientific Research, Prefectural University of Hiroshima.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Sakai
authors.forename: Hideo
authors.initials: H
authors.lastname: Onishi
authors.forename: Koji
authors.initials: K
authors.lastname: Miyazoe
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000000981:diagnostic imaging*; D001921:Brain / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods* / Q000706:statistics & numerical data