title: Lymphomas and high-grade astrocytomas: comparison of water diffusibility and histologic characteristics.
abstract: OBJECTIVE
  To determine if water diffusivity within lymphomas and high-grade astrocytomas correlates with cellularity.
  
  
  METHODS
  Echo-planar diffusion-weighted magnetic resonance (MR) images obtained in 11 patients with brain lymphomas (19 lesions) and in 17 patients with astrocytomas (19 lesions) were retrospectively reviewed. Regions of interest were drawn on apparent diffusion coefficient (ADC) maps in enhancing tumor. ADC values were normalized by dividing ADC values of tumors by those of normal-appearing regions and expressing the quotient as a ratio. Histologic samples from 11 patients with astrocytomas (11 lesions) and seven patients with lymphoma (seven lesions) were reviewed. Cellularity was measured by calculating the percentage of nuclear area and the percentage of cytoplasmic area and expressing the results as the nuclear-to-cytoplasmic (N/C) ratio. The ADC and N/C ratios of both tumor types were compared by using a two-tailed t test.
  
  
  RESULTS
  Mean ADC ratio of lymphomas was 1.15 (SD, 0.33; standard error of the mean [SEM], 0.10), and that of high-grade astrocytomas was 1.68 (SD, 0.48; SEM, 0.11) (P <.01). Mean N/C ratio of lymphoma was 1.45 (SD, 0.94; SEM, 0.36), and that of high-grade astrocytomas was 0.24 (SD, 0.18; SEM, 0.05) (P <.01).
  
  
  CONCLUSIONS
  Measurements of water diffusivity and cellularity suggest that higher cellularity contributes to more restricted diffusion.
authors.affiliation: Department of Radiology, Duke University Medical Center, Box 3808, Durham, NC 27710, USA.
authors.forename: Alexander C
authors.initials: AC
authors.lastname: Guo
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Cummings
authors.forename: Rajesh C
authors.initials: RC
authors.lastname: Dash
authors.forename: James M
authors.initials: JM
authors.lastname: Provenzale
mesh_terms: D000328:Adult; D000368:Aged; D001254:Astrocytoma / Q000378:metabolism / Q000473:pathology; D001932:Brain Neoplasms / Q000378:metabolism / Q000473:pathology; D004058:Diffusion; D017352:Echo-Planar Imaging; D005260:Female; D006801:Humans; D008223:Lymphoma / Q000378:metabolism / Q000473:pathology; D008297:Male; D008875:Middle Aged; D014867:Water
chemical_list: D014867:Water