title: A majority rule approach for region-of-interest-guided streamline fiber tractography.
abstract: Hand-drawn gray matter regions of interest (ROI) are often used to guide the estimation of white matter tractography, obtained from diffusion-weighted magnetic resonance imaging (DWI), in healthy and in patient populations. However, such ROIs are vulnerable to rater bias of the individual segmenting the ROIs, scan variability, and individual differences in neuroanatomy. In this report, a "majority rule" approach is introduced for ROI segmentation used to guide streamline tractography in white matter structures. DWI of one healthy participant was acquired in ten separate sessions using a 3 T scanner over the course of a month. Four raters identified ROIs within the left hemisphere [Cerebral Peduncle (CPED); Internal Capsule (IC); Hand Portion of the Motor Cortex, or Hand Bump, (HB)] using a group-established standard operating procedure for ROI definition to guide the estimation of streamline tracts within the corticospinal tract (CST). Each rater traced the ROIs twice for each scan session. The overlap of each rater's two ROIs was used to define a representative ROI for each rater. These ROIs were combined to create a "majority rules" ROI, in which the rule requires that each voxel is selected by at least three of four raters. Reproducibility for ROIs and CST segmentations were analyzed with the Dice Similarity Coefficient (DSC). Intra-rater reliability for each ROI was high (DSCs ≥ 0.83). Inter-rater reliability was moderate to adequate (DSC range 0.54-0.75; lowest for IC). Using intersected majority rules ROIs, the resulting CST showed improved overlap (DSC = 0.82) in the estimated streamline tracks for the ten sessions. Despite high intra-rater reliability, there was lower inter-rater reliability consistent with the expectation of rater bias. Employing the majority rules method improved reliability in the overlap of the CST.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, USA.
authors.forename: L M
authors.identifier: 0000-0001-8918-2418
authors.initials: LM
authors.lastname: Colon-Perez
authors.affiliation: Department of Physical Therapy, University of Florida, Gainesville, FL, USA.
authors.forename: W
authors.initials: W
authors.lastname: Triplett
authors.affiliation: Veterans Affairs Brain Rehabilitation Research Center, Malcolm Randall VA Center, Gainesville, FL, USA.
authors.forename: A
authors.initials: A
authors.lastname: Bohsali
authors.affiliation: Department of Pediatrics, University of Florida, Gainesville, FL, USA.
authors.forename: M
authors.initials: M
authors.lastname: Corti
authors.affiliation: Department Clinical and Health Psychology, University of Florida, Gainesville, FL, USA.
authors.forename: P T
authors.initials: PT
authors.lastname: Nguyen
authors.affiliation: Department of Physical Therapy, University of Florida, Gainesville, FL, USA.
authors.forename: C
authors.initials: C
authors.lastname: Patten
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, USA. thmareci@ufl.edu.
authors.forename: T H
authors.initials: TH
authors.lastname: Mareci
authors.affiliation: Department Clinical and Health Psychology, University of Florida, Gainesville, FL, USA. cep23@phhp.ufl.edu.
authors.forename: C C
authors.initials: CC
authors.lastname: Price
mesh_terms: D000328:Adult; D002540:Cerebral Cortex / Q000000981:diagnostic imaging*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D007839:Functional Laterality; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008297:Male; D015588:Observer Variation; D011712:Pyramidal Tracts / Q000000981:diagnostic imaging; D015203:Reproducibility of Results; D066127:White Matter / Q000000981:diagnostic imaging*
keywords: Cortico-spinal tract; Majority rules ROI; Semi-manual segmentation; Tractography