title: Regional differences in diffusion tensor imaging measurements: assessment of intrarater and interrater variability.
abstract: OBJECTIVE
  Diffusion tensor imaging (DTI) has become a valuable tool in both the research and clinical evaluation of subjects. We sought to quantify interobserver and intraobserver variability of diffusivity and diffusion anisotropy measurements with regard to specific regions of interest (ROIs).
  
  
  METHODS
  The subject group consisted of 5 healthy control subjects and 7 study subjects (all males; 16-19 years old; mean age = 17.5 years), as part of a protocol for closed head injury. Two whole-brain DTI scans were acquired on a 3T scanner for each subject. Analysis was performed using a ROI approach. Two independent observers analyzed the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) indices in the corpus callosum, cortical spinal tract, internal capsules (ICs), basal ganglia, and centrum semiovale (CSO). Intraobserver and interobserver variability were calculated for the mean ADC, FA, and ordered eigenvalues of the diffusion tensor (lambda(1), lambda(2), and lambda(3)).
  
  
  RESULTS
  The overall kappa statistic for intraobserver variability for both observers showed slight-to-substantial agreement (kappa = 0.02-0.69), however FA values in the CSO showed only slight agreement. Interobserver agreement was also slight to substantial for these DTI measurements with high variability in FA values in the IC and CSO.
  
  
  CONCLUSIONS
  When one is comparing 2 DTI measurements, it is important to assess intraobserver and interobserver variability. We recommend caution in the analysis of DTI contrasts in the IC and CSO, because we have found the widest range of variability in measurements within these structures.
authors: Russell H. Morgan Department of Radiology and Radiological Science, F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD 21287, USA.
authors: A
authors: A
authors: Ozturk
authors: A D
authors: AD
authors: Sasson
authors: J A D
authors: JA
authors: Farrell
authors: B A
authors: BA
authors: Landman
authors: A C B S
authors: AC
authors: da Motta
authors: A
authors: A
authors: Aralasmak
authors: D M
authors: DM
authors: Yousem
mesh_terms: D000293:Adolescent; D000328:Adult; D001921:Brain / Q000473:pathology*; D001930:Brain Injuries / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D006801:Humans; D008297:Male; D015588:Observer Variation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity