title: Influence of analysis technique on measurement of diffusion tensor imaging parameters.
abstract: OBJECTIVE
  We compared results from various methods of analysis of diffusion tensor imaging (DTI) data from a single dataset consisting of 10 healthy adolescents.
  
  
  METHODS
  All subjects were imaged on a single 3-T MRI system (single-shot echo-planar imaging pulse sequence; b value, 1000 s/mm(2)). We measured fractional anisotropy (FA), apparent diffusion coefficient (ADC), and axial and radial diffusivity values using 64-pixel rectangular regions of interest (ROIs) in the right side, midline, and left side of the central portion of the splenium of the corpus callosum for fixed (i.e., at same sites in all subjects) and targeted (i.e., at sites of highest FA values) locations. We compared results with those obtained using 64-pixel oval ROIs and 100-pixel rectangular ROIs in the same locations. Finally, we compared results from ROI-based methods and from tractography. All comparisons used the Wilcoxon signed rank test and the intraclass correlation of individual values.
  
  
  RESULTS
  Compared to tractography, the average of mean ROI-based values was significantly higher for fixed (approximately 14%) and targeted (approximately 39%) FA values and was significantly lower for ADC (approximately 16%) and radial diffusivity (approximately 38%) values. For solely ROI-based comparisons, statistically significant differences were found in the following comparisons: 64- versus 100-pixel ROI, oval versus rectangular ROI, targeted FA left of midline versus mean targeted FA value, and targeted ROI right of midline versus mean targeted FA value.
  
  
  CONCLUSIONS
  Markedly different values were obtained when using either ROI- or tractography-based techniques or ROI analysis techniques that differ only relatively slightly.
authors.affiliation: Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: Efsun
authors.initials: E
authors.lastname: Urger
authors.forename: Michael D
authors.initials: MD
authors.lastname: Debellis
authors.forename: Steven R
authors.initials: SR
authors.lastname: Hooper
authors.forename: Donald P
authors.initials: DP
authors.lastname: Woolley
authors.forename: Steven
authors.initials: S
authors.lastname: Chen
authors.forename: James M
authors.initials: JM
authors.lastname: Provenzale
mesh_terms: D000293:Adolescent; D000465:Algorithms; D002648:Child; D002675:Child, Preschool; D003337:Corpus Callosum / Q000033:anatomy & histology*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D009413:Nerve Fibers, Myelinated / Q000648:ultrastructure*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity