title: Improvements in the quantitative assessment of cerebral blood volume and flow with the removal of vessel voxels from MR perfusion images.
abstract: OBJECTIVE
  To improve the quantitative assessment of cerebral blood volume (CBV) and flow (CBF) in the brain voxels from MR perfusion images.
  
  
  METHODS
  Normal brain parenchyma was automatically segmented with the time-to-peak criteria after cerebrospinal fluid removal and preliminary vessel voxel removal. Two scaling factors were calculated by comparing the relative CBV and CBF of the segmented normal brain parenchyma with the absolute values in the literature. Using the scaling factors, the relative values were converted to the absolute CBV and CBF. Voxels with either CBV > 8 mL/100 g or CBF > 100 mL/100 g/min were characterized as vessel voxels and were excluded from the quantitative measurements.
  
  
  RESULTS
  The segmented brain parenchyma with normal perfusion was consistent with the angiographic findings for each patient. We confirmed the necessity of dual thresholds including CBF and CBV for proper removal of vessel voxels. The scaling factors were 0.208 ± 0.041 for CBV, and 0.168 ± 0.037, 0.172 ± 0.037 for CBF calculated using standard and circulant singular value decomposition techniques, respectively.
  
  
  CONCLUSIONS
  The automatic scaling and vessel removal techniques provide an alternative method for obtaining improved quantitative assessment of CBV and CBF in patients with thromboembolic cerebral arterial disease.
authors.affiliation: School of Medicine, National Yang Ming University, Taipei 112, Taiwan.
authors.forename: Michael Mu Huo
authors.initials: MM
authors.lastname: Teng
authors.forename: I-Chieh
authors.initials: IC
authors.lastname: Cho
authors.forename: Yi-Hsuan
authors.initials: YH
authors.lastname: Kao
authors.forename: Chi-Shuo
authors.initials: CS
authors.lastname: Chuang
authors.forename: Fang-Ying
authors.initials: FY
authors.lastname: Chiu
authors.forename: Feng-Chi
authors.initials: FC
authors.lastname: Chang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001783:Blood Flow Velocity; D001810:Blood Volume; D001921:Brain / Q000098:blood supply* / Q000000981:diagnostic imaging / Q000502:physiology; D002560:Cerebrovascular Circulation; D003952:Diagnostic Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011859:Radiography; D013923:Thromboembolism / Q000000981:diagnostic imaging / Q000473:pathology*