title: A computed tomography-based spatial normalization for the analysis of [18F] fluorodeoxyglucose positron emission tomography of the brain.
abstract: OBJECTIVE
  We developed a new computed tomography (CT)-based spatial normalization method and CT template to demonstrate its usefulness in spatial normalization of positron emission tomography (PET) images with [(18)F] fluorodeoxyglucose (FDG) PET studies in healthy controls.
  
  
  METHODS
  Seventy healthy controls underwent brain CT scan (120 KeV, 180 mAs, and 3 mm of thickness) and [(18)F] FDG PET scans using a PET/CT scanner. T1-weighted magnetic resonance (MR) images were acquired for all subjects. By averaging skull-stripped and spatially-normalized MR and CT images, we created skull-stripped MR and CT templates for spatial normalization. The skull-stripped MR and CT images were spatially normalized to each structural template. PET images were spatially normalized by applying spatial transformation parameters to normalize skull-stripped MR and CT images. A conventional perfusion PET template was used for PET-based spatial normalization. Regional standardized uptake values (SUV) measured by overlaying the template volume of interest (VOI) were compared to those measured with FreeSurfer-generated VOI (FSVOI).
  
  
  RESULTS
  All three spatial normalization methods underestimated regional SUV values by 0.3-20% compared to those measured with FSVOI. The CT-based method showed slightly greater underestimation bias. Regional SUV values derived from all three spatial normalization methods were correlated significantly (p < 0.0001) with those measured with FSVOI.
  
  
  CONCLUSIONS
  CT-based spatial normalization may be an alternative method for structure-based spatial normalization of [(18)F] FDG PET when MR imaging is unavailable. Therefore, it is useful for PET/CT studies with various radiotracers whose uptake is expected to be limited to specific brain regions or highly variable within study population.
authors.affiliation: Department of Neurology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul 135-720, Korea.
authors.forename: Hanna
authors.initials: H
authors.lastname: Cho
authors.affiliation: Molecular Imaging Research Center, Korea Institute Radiological and Medical Science, Seoul 139-706, Korea.
authors.forename: Jin Su
authors.initials: JS
authors.lastname: Kim
authors.affiliation: Department of Nuclear Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul 135-720, Korea.
authors.forename: Jae Yong
authors.initials: JY
authors.lastname: Choi
authors.affiliation: Department of Nuclear Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul 135-720, Korea.
authors.forename: Young Hoon
authors.initials: YH
authors.lastname: Ryu
authors.affiliation: Department of Neurology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul 135-720, Korea.
authors.forename: Chul Hyoung
authors.initials: CH
authors.lastname: Lyoo
mesh_terms: D000328:Adult; D000368:Aged; D001921:Brain / Q000000981:diagnostic imaging* / Q000473:pathology; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D014057:Tomography, X-Ray Computed
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: CT; Spatial normalization; Template; [18F] FDG PET