title: Reproducibility of Tract-based and Region-of-Interest DTI Analysis of Long Association Tracts.
abstract: OBJECTIVE
  Reproducibility of two different methods for quantifying fiber tracts by using a diffusion tensor imaging (DTI) sequence suitable for clinical magnetic resonance imaging (MRI) protocols was evaluated.
  
  
  METHODS
  DTI of 15 subjects was used to analyze intra-rater and inter-rater reproducibility. Another 10 subjects underwent MRI twice for assessment of between-scan reliability. Ten long association tracts were defined by fiber tracking using inclusion and exclusion regions of interest (ROIs). Whole-tract analysis and tractography-based core analysis were performed, and the effect of fractional anisotropy (FA 0.15/0.30) and turning angle threshold (27°/60°) on reproducibility was evaluated. Additionally, ROI measurements were performed in the core of the tracts.
  
  
  RESULTS
  For the tract-based methods, intra-rater and inter-rater reliabilities of FA and mean diffusivity (MD) measurements were excellent. Between-scan reproducibility was good or excellent in 127 of 130 of the measurements. There was no systematic difference in the reproducibility of the FA, MD, and volume measurements depending on the FA or turning angle threshold. For the cross-sectional ROI measurements, reliability showed large variation from poor to excellent depending on the tract.
  
  
  CONCLUSIONS
  Compared with the commonly used cross-sectional core ROI method, the tract-based analyses seem to be a more robust way to identify and measure white matter tracts of interest, and provide a novel reproducible tool to perform core analysis.
authors.affiliation: Department of Radiology, Helsinki University Hospital, PL 340, 00029, HUS, Finland. nina.brandstack@hus.fi.
authors.forename: N
authors.initials: N
authors.lastname: Brandstack
authors.affiliation: Department of Radiology, Terveystalo Turku Pulssi Medical Centre, Turku, Finland.
authors.forename: T
authors.initials: T
authors.lastname: Kurki
authors.affiliation: Department of Radiology, Turku University Hospital, PL 52, 20521, Turku, Finland.
authors.forename: J
authors.initials: J
authors.lastname: Laalo
authors.affiliation: Department of Biostatistics, University of Turku, Turku, Finland.
authors.forename: T
authors.initials: T
authors.lastname: Kauko
authors.affiliation: Department of Neurology, Turku University Hospital, PL 52, 20521, Turku, Finland.
authors.forename: O
authors.initials: O
authors.lastname: Tenovuo
mesh_terms: D000293:Adolescent; D000328:Adult; D016880:Anisotropy; D001921:Brain / Q000000981:diagnostic imaging / Q000473:pathology*; D000070642:Brain Injuries, Traumatic / Q000000981:diagnostic imaging / Q000473:pathology*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D066127:White Matter / Q000000981:diagnostic imaging / Q000473:pathology*; D055815:Young Adult
keywords: Core ROI method; DTI tractography; Reproducibility; Tract-based analyses