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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.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 (Ktrans), ve, and VD.Parameter values in regions where the standard model was selected as the best model were: (mean ± S.D.): vp = (0.81 ± 0.40)%, Ktrans = (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).These data suggest that tumor cellularity can be estimated noninvasively by DCE-MRI, thus supporting its utility in assessing tumor pathophysiology. Magn Reson Med 71:2206–2214, 2014. © 2013 Wiley Periodicals, Inc.