title: Differences in CT perfusion maps generated by different commercial software: quantitative analysis by using identical source data of acute stroke patients.
abstract: OBJECTIVE
  To examine the variability in the qualitative and quantitative results of computed tomographic (CT) perfusion imaging generated from identical source data of stroke patients by using commercially available software programs provided by various CT manufacturers.
  
  
  METHODS
  Institutional review board approval and informed consent were obtained. CT perfusion imaging data of 10 stroke patients were postprocessed by using five commercial software packages, each of which had a different algorithm: singular-value decomposition (SVD), maximum slope (MS), inverse filter (IF), box modulation transfer function (bMTF), and by using custom-made original software with standard (sSVD) and block-circulant (bSVD) SVD methods. Areas showing abnormalities in cerebral blood flow (CBF), mean transit time (MTT), and cerebral blood volume (CBV) were compared with each other and with the final infarct areas. Differences among the ratios of quantitative values in the final infarct areas and those in the unaffected side were also examined.
  
  
  RESULTS
  The areas with CBF or MTT abnormalities and the ratios of these values significantly varied among software, while those of CBV were stable. The areas with CBF or MTT abnormalities analyzed by using SVD or bMTF corresponded to those obtained with delay-sensitive sSVD, but overestimated the final infarct area. The values obtained from software by using MS or IF corresponded well with those obtained from the delay-insensitive bSVD and the final infarct area. Given the similarities between CBF and MTT, all software were separated in two groups (ie, sSVD and bSVD). The ratios of CBF or MTTs correlated well within both groups, but not across them.
  
  
  CONCLUSIONS
  CT perfusion imaging maps were significantly different among commercial software even when using identical source data, presumably because of differences in tracer-delay sensitivity.
authors.affiliation: Advanced Medical Research Center, Iwate Medical University; 19-1 Uchimaru, Morioka 020-8505, Japan. kokudo@iwate-med.ac.jp
authors.forename: Kohsuke
authors.initials: K
authors.lastname: Kudo
authors.forename: Makoto
authors.initials: M
authors.lastname: Sasaki
authors.forename: Kei
authors.initials: K
authors.lastname: Yamada
authors.forename: Suketaka
authors.initials: S
authors.lastname: Momoshima
authors.forename: Hidetsuna
authors.initials: H
authors.lastname: Utsunomiya
authors.forename: Hiroki
authors.initials: H
authors.lastname: Shirato
authors.forename: Kuniaki
authors.initials: K
authors.lastname: Ogasawara
mesh_terms: D000368:Aged; D000465:Algorithms; D000704:Analysis of Variance; D002560:Cerebrovascular Circulation; D003287:Contrast Media / Q000008:administration & dosage; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007479:Iopamidol / Q000008:administration & dosage; D016014:Linear Models; D008297:Male; D011856:Radiographic Image Enhancement / Q000379:methods; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012984:Software; D020521:Stroke / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007479:Iopamidol