title: Performance of model observers for lesion detection in SPECT imaging.
abstract: We investigated the performance of model observers (the channelized Hotelling observer (CHO), channelized non-prewhitening observer (CNPWO) and non-prewhitening observer (NPWO)) for lesion detection in single photon emission computed tomography (SPECT) imaging.
  
  
  METHODS
  Using a simulation tool, we generated the numerical phantom with a hot lesion for cases having various contrasts and sizes and projection data including photon attenuation, scatter and distance-dependent collimator-detector response. The SPECT images were reconstructed using the filtered back-projection method and the ordered-subsets expectation-maximization method. Fifty lesion-absent and lesion-present images were generated and the detectability indices derived from CHO (d(CHO)), CNPWO (d(CNPWO)) and NPWO (d(NPWO)) were calculated from a total of 100 images. These procedures were repeated 5 times for each condition. The relationships among these detectability indices were investigated for various projection counts, lesion contrasts and lesion sizes.
  
  
  RESULTS
  All detectability indices increased with increases of projection count, lesion contrast and lesion size. Although there were good correlations among them, the relationships between d(CHO) and d(NPWO) and between d(CNPWO) and d(NPWO) were not linear. The coefficient of variation of d(CHO) tended to be significantly greater than that of d(CNPWO) and d(NPWO).
  
  
  CONCLUSIONS
  This study will be useful for understanding the performance of model observers when evaluating lesion detection in SPECT imaging.
authors.affiliation: Department of Medical Physics and Engineering, Division of Medical Technology and Science, Course of Health Science, Graduate School of Medicine, Osaka University, 1-7 Yamadaoka, Suita-shi, Osaka, 565-0871, Japan. murase@sahs.med.osaka-u.ac.jp.
authors.forename: Kenya
authors.initials: K
authors.lastname: Murase
authors.forename: Wataru
authors.initials: W
authors.lastname: Mukai
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Fukami
authors.forename: Keiichi
authors.initials: K
authors.lastname: Matsumoto
authors.forename: Ziaomei
authors.initials: Z
authors.lastname: Yang
mesh_terms: D006801:Humans; D007091:Image Processing, Computer-Assisted; D008962:Models, Theoretical; D015588:Observer Variation; D019047:Phantoms, Imaging; D015899:Tomography, Emission-Computed, Single-Photon