title: Peritumoral edema of meningiomas and metastatic brain tumors: differences in diffusion characteristics evaluated with diffusion-tensor MR imaging.
abstract: BACKGROUND
  We prospectively compared the fractional anisotropy (FA) and mean diffusivity (MD) of the peritumoral edema of meningiomas and metastatic brain tumors with diffusion-tensor magnetic resonance (MR) imaging.
  
  
  METHODS
  The study protocol was approved by the local ethics committee, and written informed consent was obtained. Preoperative diffusion-tensor MR imaging was performed in 15 patients with meningiomas and 11 patients with metastatic brain tumors. Regions of interest (ROI) were placed in the peritumoral edema and normal-appearing white matter (NAWM) of the contralateral hemisphere to measure the FA and MD. The FA and MD ratios were calculated for each ROI in relation to the NAWM of the contralateral hemisphere. Changes in peritumoral MD and FA, in terms of primary values and ratios, were compared using a two-sample t-test; P < 0.05 was taken as indicating statistical significance.
  
  
  RESULTS
  The mean MD values (x10(-3) mm(2)/s) of the peritumoral edema for metastases and meningiomas, respectively, were 0.902 +/- 0.057 and 0.820 +/- 0.094, the mean MD ratios were 220.3 +/- 22.6 and 193.1 +/- 23.4, the mean FA values were 0.146 +/- 0.026 and 0.199 +/- 0.052, and the mean FA ratios were 32.3 +/- 5.9 and 46.0 +/- 12.1. All the values were significantly different between metastases and meningiomas (MD values P = 0.016, MD ratios P = 0.006, FA values P = 0.005, FA ratios P = 0.002).
  
  
  CONCLUSIONS
  The peritumoral edema of metastatic brain tumors and meningiomas show different MD and FA on diffusion-tensor MR imaging.
authors.affiliation: Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital, Kwei Shan Hsiang, Tao-Yuan, Taiwan. eldomtoh@ms53.hinet.net
authors.forename: Cheng-Hong
authors.initials: CH
authors.lastname: Toh
authors.forename: Alex M-C
authors.initials: AM
authors.lastname: Wong
authors.forename: Kuo-Chen
authors.initials: KC
authors.lastname: Wei
authors.forename: Shu-Hang
authors.initials: SH
authors.lastname: Ng
authors.forename: Ho-Fai
authors.initials: HF
authors.lastname: Wong
authors.forename: Yung-Liang
authors.initials: YL
authors.lastname: Wan
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016880:Anisotropy; D001929:Brain Edema / Q000209:etiology / Q000378:metabolism* / Q000473:pathology*; D001932:Brain Neoplasms / Q000378:metabolism / Q000473:pathology / Q000556:secondary*; D004058:Diffusion; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D008297:Male; D008577:Meningeal Neoplasms / Q000150:complications* / Q000378:metabolism / Q000473:pathology; D008579:Meningioma / Q000150:complications* / Q000378:metabolism / Q000473:pathology; D008875:Middle Aged; D011446:Prospective Studies