title: Diffusion tensor eigenvector directional color imaging patterns in the evaluation of cerebral white matter tracts altered by tumor.
abstract: OBJECTIVE
  To categorize the varied appearances of tumor-altered white matter (WM) tracts on diffusion tensor eigenvector directional color maps.
  
  
  METHODS
  Diffusion tensor imaging (DTI) was obtained preoperatively in 13 patients with brain tumors ranging from benign to high-grade malignant, including primary and metastatic lesions, and maps of apparent diffusion coefficient (ADC), fractional anisotropy (FA), and major eigenvector direction were generated. Regions of interest (ROIs) were drawn within identifiable WM tracts affected by tumor, avoiding grossly cystic and necrotic regions, known fiber crossings, and gray matter. Patterns of WM tract alteration were categorized on the basis of qualitative analysis of directional color maps and correlation analysis of ADC and FA.
  
  
  RESULTS
  Four basic patterns of WM alteration were identified: 1) normal or nearly normal FA and ADC, with abnormal tract location or tensor directions attributable to bulk mass displacement, 2) moderately decreased FA and increased ADC with normal tract locations and tensor directions, 3) moderately decreased FA and increased ADC with abnormal tensor directions, and 4) near isotropy. FA and ADC were inversely correlated for Patterns 1-3 but did not discriminate edema from infiltrating tumor. However, in the absence of mass displacement, infiltrating tumor was found to produce tensor directional changes that were not observed with vasogenic edema, suggesting the possibility of discrimination on the basis of directional statistics.
  
  
  CONCLUSIONS
  Tumor alteration of WM tracts tends to produce one of four patterns on FA and directional color maps. Clinical application of these patterns must await further study.
authors.affiliation: Department of Radiology, University of Wisconsin Medical School, Madison, Wisconsin 53792-3252, USA. as.field@hosp.wisc.edu
authors.forename: Aaron S
authors.initials: AS
authors.lastname: Field
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Alexander
authors.forename: Yu-Chien
authors.initials: YC
authors.lastname: Wu
authors.forename: Khader M
authors.initials: KM
authors.lastname: Hasan
authors.forename: Brian
authors.initials: B
authors.lastname: Witwer
authors.forename: Behnam
authors.initials: B
authors.lastname: Badie
mesh_terms: D000328:Adult; D000368:Aged; D016880:Anisotropy; D001931:Brain Mapping / Q000379:methods; D001932:Brain Neoplasms / Q000473:pathology*; D003116:Color; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged