title: Comparative study of anatomical normalization errors in SPM and 3D-SSP using digital brain phantom.
abstract: OBJECTIVE
  In single photon emission computed tomography (SPECT) cerebral blood flow studies, two major algorithms are widely used statistical parametric mapping (SPM) and three-dimensional stereotactic surface projections (3D-SSP). The aim of this study is to compare an SPM algorithm-based easy Z score imaging system (eZIS) and a 3D-SSP system in the errors of anatomical standardization using 3D-digital brain phantom images.
  
  
  METHODS
  We developed a 3D-brain digital phantom based on MR images to simulate the effects of head tilt, perfusion defective region size, and count value reduction rate on the SPECT images. This digital phantom was used to compare the errors of anatomical standardization by the eZIS and the 3D-SSP algorithms.
  
  
  RESULTS
  While the eZIS allowed accurate standardization of the images of the phantom simulating a head in rotation, lateroflexion, anteflexion, or retroflexion without angle dependency, the standardization by 3D-SSP was not accurate enough at approximately 25° or more head tilt. When the simulated head contained perfusion defective regions, one of the 3D-SSP images showed an error of 6.9% from the true value. Meanwhile, one of the eZIS images showed an error as large as 63.4%, revealing a significant underestimation.
  
  
  CONCLUSIONS
  When required to evaluate regions with decreased perfusion due to such causes as hemodynamic cerebral ischemia, the 3D-SSP is desirable. In a statistical image analysis, we must reconfirm the image after anatomical standardization by all means.
authors.affiliation: Prefectural University of Hiroshima, Mihara, Japan. onisi@pu-hiroshima.ac.jp
authors.forename: Hideo
authors.initials: H
authors.lastname: Onishi
authors.forename: Yuki
authors.initials: Y
authors.lastname: Matsutake
authors.forename: Hiroki
authors.initials: H
authors.lastname: Kawashima
authors.forename: Norikazu
authors.initials: N
authors.lastname: Matsutomo
authors.forename: Hizuru
authors.initials: H
authors.lastname: Amijima
mesh_terms: D001921:Brain / Q000033:anatomy & histology* / Q000098:blood supply / Q000000981:diagnostic imaging; D002560:Cerebrovascular Circulation; D006257:Head / Q000502:physiology; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000295:instrumentation* / Q000592:standards*; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D019047:Phantoms, Imaging; D012015:Reference Standards; D012399:Rotation; D013238:Stereotaxic Techniques / Q000295:instrumentation*; D015899:Tomography, Emission-Computed, Single-Photon