title: Abnormalities in the recirculation phase of contrast agent bolus passage in cerebral gliomas: comparison with relative blood volume and tumor grade.
abstract: OBJECTIVE
  Abnormalities in the recirculation phase of the passage of a contrast agent bolus have been identified in tumors and have been suggested to represent vascular tortuosity and hypoperfusion in areas of angiogenic neovascularization. This study was performed to examine the hypothesis that these abnormalities provide information concerning the microcirculation related to tumor grade in patients with cerebral glioma.
  
  
  METHODS
  Contrast-enhanced dynamic susceptibility MR imaging was performed in 27 patients with glioma. Residual relaxivity effects were minimized by injection of contrast agent before dynamic imaging. Maps of relative cerebral blood volume (rCBV) and relative recirculation (rR) were calculated, and values from enhancing tumor tissue were compared with tumor grade.
  
  
  RESULTS
  Histologic grades were grade II, astrocytoma (n = 3); grade III, anaplastic astrocytoma (n = 10); and grade IV, glioblastoma multiforme (n = 14). rCBV values varied among tumor grades, with higher mean values in higher grade tumors (P <.001). Mean rR values in grade II tumors were not significantly different from those in normal gray and white matter. Mean rR values in grades III and IV tumors were similar and were significantly higher than those in grade II tumors (P <.01). The distribution of the pixel values of rR showed significant differences between grades III and IV tumors (P <.001), with low values of skewness in keeping with a normal distribution in grade III tumors and higher values in grade IV tumors.
  
  
  CONCLUSIONS
  Variation in the recirculation characteristics of a contrast agent bolus is related to tumor grade in gliomas. This supports the hypothesis that abnormalities in contrast agent recirculation provide independent information concerning the microcirculation in imaging studies of angiogenesis and may be of value as surrogate markers in trials of antiangiogenic therapy.
authors.affiliation: Imaging Science and Biomedical Engineering, Stopford Building, University of Manchester, Oxford Road, Manchester M13 9PT, United Kingdom.
authors.forename: Alan
authors.initials: A
authors.lastname: Jackson
authors.forename: Andrea
authors.initials: A
authors.lastname: Kassner
authors.forename: Deborah
authors.initials: D
authors.lastname: Annesley-Williams
authors.forename: Helen
authors.initials: H
authors.lastname: Reid
authors.forename: Xiau-Ping
authors.initials: XP
authors.lastname: Zhu
authors.forename: Kah-Loh
authors.initials: KL
authors.lastname: Li
mesh_terms: D000328:Adult; D000368:Aged; D001254:Astrocytoma / Q000098:blood supply / Q000175:diagnosis / Q000473:pathology; D001706:Biopsy; D001783:Blood Flow Velocity / Q000502:physiology; D001810:Blood Volume / Q000502:physiology; D001921:Brain / Q000098:blood supply / Q000473:pathology; D001932:Brain Neoplasms / Q000098:blood supply* / Q000175:diagnosis / Q000473:pathology; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D005909:Glioblastoma / Q000098:blood supply / Q000175:diagnosis / Q000473:pathology; D005910:Glioma / Q000098:blood supply* / Q000175:diagnosis / Q000473:pathology; D006801:Humans; D007089:Image Enhancement; D008279:Magnetic Resonance Imaging; D008297:Male; D008833:Microcirculation / Q000473:pathology / Q000503:physiopathology; D008875:Middle Aged; D009389:Neovascularization, Pathologic / Q000175:diagnosis* / Q000473:pathology; D012189:Retrospective Studies
chemical_list: D003287:Contrast Media; C064925:gadodiamide; D019786:Gadolinium DTPA