title: Dynamic contrast enhanced MRI parameters and tumor cellularity in a rat model of cerebral glioma at 7 T.
abstract: OBJECTIVE
  To test the hypothesis that a noninvasive dynamic contrast enhanced MRI (DCE-MRI) derived interstitial volume fraction (ve ) and/or distribution volume (VD ) were correlated with tumor cellularity in cerebral tumor.
  
  
  METHODS
  T1 -weighted DCE-MRI studies were performed in 18 athymic rats implanted with U251 xenografts. After DCE-MRI, sectioned brain tissues were stained with Hematoxylin and Eosin for cell counting. Using a Standard Model analysis and Logan graphical plot, DCE-MRI image sets during and after the injection of a gadolinium contrast agent were used to estimate the parameters plasma volume (vp ), forward transfer constant (K(trans) ), ve , and VD .
  
  
  RESULTS
  Parameter values in regions where the standard model was selected as the best model were: (mean ± S.D.): vp = (0.81 ± 0.40)%, K(trans) = (2.09 ± 0.65) × 10(-2) min(-1) , ve = (6.65 ± 1.86)%, and VD = (7.21 ± 1.98)%. The Logan-estimated VD was strongly correlated with the standard model's vp + ve (r = 0.91, P < 0.001). The parameters, ve and/or VD , were significantly correlated with tumor cellularity (r ≥ -0.75, P < 0.001 for both).
  
  
  CONCLUSIONS
  These data suggest that tumor cellularity can be estimated noninvasively by DCE-MRI, thus supporting its utility in assessing tumor pathophysiology.
authors.affiliation: Department of Physics, Oakland University, Rochester, Michigan, USA; Department of Neurology, Henry Ford Hospital, Detroit, Michigan, USA.
authors.forename: Madhava P
authors.initials: MP
authors.lastname: Aryal
authors.forename: Tavarekere N
authors.initials: TN
authors.lastname: Nagaraja
authors.forename: Kelly A
authors.initials: KA
authors.lastname: Keenan
authors.forename: Hassan
authors.initials: H
authors.lastname: Bagher-Ebadian
authors.forename: Swayamprava
authors.initials: S
authors.lastname: Panda
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Brown
authors.forename: Glauber
authors.initials: G
authors.lastname: Cabral
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Fenstermacher
authors.forename: James R
authors.initials: JR
authors.lastname: Ewing
mesh_terms: D000465:Algorithms; D000818:Animals; D001932:Brain Neoplasms / Q000473:pathology*; D003287:Contrast Media; D004195:Disease Models, Animal; D017352:Echo-Planar Imaging; D019786:Gadolinium DTPA; D005910:Glioma / Q000473:pathology*; D064593:Heterografts; D008279:Magnetic Resonance Imaging / Q000379:methods*; D051381:Rats; D011923:Rats, Nude
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA
keywords: DCE-MRI; Logan plot; distribution volume; dual-echo gradient-echo sequence; interstitial volume; longitudinal relaxation rate; tumor cellularity