title: Perfusion CT vascular parameters do not correlate with immunohistochemically derived microvessel density count in colorectal tumors.
abstract: OBJECTIVE
  To determine whether perfusion computed tomography (CT)-derived vascular parameters-namely, blood flow, mean transit time (MTT), volume transfer constant (K(trans)), permeability-surface area product (PS), extracellular extravascular space volume, and vascular volume-correlate with the immunohistologic markers of angiogenesis in colorectal tumors.
  
  
  METHODS
  This prospective study was approved by the Regional Ethics and Research and Development Committees. The perfusion CT protocol was incorporated in the staging CT after informed consent in 29 patients (14 men, 15 women; mean age, 70 years; age range, 55-94 years). The perfusion parameters were calculated over two regions of interest (ROIs), at the invasive and luminal site defined by two radiologists independently. Accurate representative data were captured manually by correcting for motion artifacts and were analyzed by using Matlab software. The vascular heterogeneity between ROIs was assessed by using the Wilcoxon signed rank test. Perfusion CT parameters were correlated with the microvessel density (MVD) count at both corresponding sites obtained by means of immunohistochemical staining of the selected histologic slide with factor VIII and CD105 antigens by using Spearmen rank coefficient.
  
  
  RESULTS
  There was no statistically significant difference found between perfusion CT vascular parameters at the two ROIs by either of the radiologists. The Pearson coefficient for blood flow, MTT, K(trans), and PS at the two ROIs demonstrated good to moderate interobserver variability (for the two ROIs, 0.46 and 0.44; 0.67 and 0.64; 0.41 and 0.72; and 0.86 and 0.56, respectively). None of these parameters correlated with MVD count at the invasive or the luminal site for either of the two antigens.
  
  
  CONCLUSIONS
  Perfusion CT measurements may measure vascularity of colorectal tumors, however, correlation with MVD, which is a morphologic measure, appears inappropriate. © RSNA, 2013.
authors.affiliation: Department of Surgery, Mayday University Hospital NHS Trust, Croydon, London, England.
authors.forename: Shwetal
authors.initials: S
authors.lastname: Dighe
authors.forename: Helena
authors.initials: H
authors.lastname: Blake
authors.forename: Nelesh
authors.initials: N
authors.lastname: Jeyadevan
authors.forename: Isabel
authors.initials: I
authors.lastname: Castellano
authors.forename: Dow-Mu
authors.initials: DM
authors.lastname: Koh
authors.forename: Matthew
authors.initials: M
authors.lastname: Orton
authors.forename: Ian
authors.initials: I
authors.lastname: Chandler
authors.forename: Ian
authors.initials: I
authors.lastname: Swift
authors.forename: Gina
authors.initials: G
authors.lastname: Brown
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D015179:Colorectal Neoplasms / Q000098:blood supply* / Q000000981:diagnostic imaging*; D003287:Contrast Media; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D007472:Iohexol; D008297:Male; D055806:Microvessels; D008875:Middle Aged; D009389:Neovascularization, Pathologic / Q000000981:diagnostic imaging*; D011446:Prospective Studies; D011857:Radiographic Image Interpretation, Computer-Assisted; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007472:Iohexol