title: Comparative study of methods for determining vascular permeability and blood volume in human gliomas.
abstract: OBJECTIVE
  To characterize human gliomas using T1-weighted dynamic contrast-enhanced MRI (DCE-MRI), and directly compare three pharmacokinetic analysis techniques: a conventional established technique and two novel techniques that aim to reduce erroneous overestimation of the volume transfer constant between plasma and the extravascular extracellular space (EES) (Ktrans) in areas of high blood volume.
  
  
  METHODS
  Eighteen patients with high-grade gliomas underwent DCE-MRI. Three kinetic models were applied to estimate Ktrans and fractional blood plasma volume (vp). We applied the Tofts and Kermode (TK) model without arterial input function (AIF) estimation, the TK model modified to include vp and AIF estimation (mTK), and a "first pass" variant of the TK model (FP).
  
  
  RESULTS
  KTK values were considerably higher than KmTK and KFP values (P <0.001). KmTK and KFP were more comparable and closely correlated (rho=0.744), with KmTK generally higher than KFP (P <0.001). Estimates of vp(mTK) and vp(FP) also showed a significant difference (P <0.001); however, these values were very closely correlated (rho=0.901). KTK parameter maps showed "pseudopermeability" effects displaying numerous vessels. These were not visualized on KmTK and KFP maps but appeared on the corresponding vp maps, indicating a failure of the TK model in commonly occurring vascular regions.
  
  
  CONCLUSIONS
  Both of the methods that incorporate a measured AIF and an estimate of vp provide similar pathophysiological information and avoid erroneous overestimation of Ktrans in areas of significant vessel density, and thus allow a more accurate estimation of endothelial permeability.
authors.affiliation: Department of Neurology, Aachen University Hospital, Aachen, Germany.
authors.forename: Judith U
authors.initials: JU
authors.lastname: Harrer
authors.forename: Geoff J M
authors.initials: GJ
authors.lastname: Parker
authors.forename: Hamied A
authors.initials: HA
authors.lastname: Haroon
authors.forename: David L
authors.initials: DL
authors.lastname: Buckley
authors.forename: Karl
authors.initials: K
authors.lastname: Embelton
authors.forename: Caleb
authors.initials: C
authors.lastname: Roberts
authors.forename: Danielle
authors.initials: D
authors.lastname: Balériaux
authors.forename: Alan
authors.initials: A
authors.lastname: Jackson
mesh_terms: D000328:Adult; D000368:Aged; D001254:Astrocytoma / Q000098:blood supply / Q000175:diagnosis / Q000503:physiopathology*; D001810:Blood Volume; D001932:Brain Neoplasms / Q000098:blood supply / Q000175:diagnosis / Q000503:physiopathology*; D002199:Capillary Permeability; D002560:Cerebrovascular Circulation / Q000502:physiology; D003287:Contrast Media / Q000008:administration & dosage / Q000493:pharmacokinetics; D005260:Female; D019786:Gadolinium DTPA / Q000008:administration & dosage / Q000493:pharmacokinetics; D005909:Glioblastoma / Q000098:blood supply / Q000175:diagnosis / Q000503:physiopathology*; D005910:Glioma / Q000098:blood supply / Q000175:diagnosis / Q000503:physiopathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D008954:Models, Biological
chemical_list: D003287:Contrast Media; C064925:gadodiamide; D019786:Gadolinium DTPA