title: Correction for diffusion MRI fibre tracking biases: The consequences for structural connectomic metrics.
abstract: Diffusion MRI streamlines tractography has become a major technique for inferring structural networks through reconstruction of brain connectome. However, quantification of structural connectivity based on the number of streamlines interconnecting brain grey matter regions is known to be problematic in a number of aspects, such as the ill-posed nature of streamlines terminations and the non-quantitative nature of streamline counts. This study investigates the effects of state-of-the-art connectome construction methods on the subsequent analyses of structural brain networks using graph theoretical approaches. Our results demonstrate that the characteristics of structural connectivity, including connectome variability, global network metrics, small-world attributes and network hubs, alter significantly following the improvement in biological accuracy of streamlines tractograms provided by anatomically-constrained tractography (ACT) and spherical-deconvolution informed filtering of tractograms (SIFT). Importantly, the commonly-used correction for connection density based on scaling the contribution of each streamline to the connectome by its inverse length is shown to provide incomplete correction, highlighting the necessity for the use of advanced tractogram reconstruction techniques in structural connectomics research.
authors.affiliation: Florey Institute of Neuroscience and Mental Health, Melbourne, Victoria, Australia. Electronic address: chun-hung.yeh@florey.edu.au.
authors.forename: Chun-Hung
authors.initials: CH
authors.lastname: Yeh
authors.affiliation: Florey Institute of Neuroscience and Mental Health, Melbourne, Victoria, Australia.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Smith
authors.affiliation: Florey Institute of Neuroscience and Mental Health, Melbourne, Victoria, Australia.
authors.forename: Xiaoyun
authors.initials: X
authors.lastname: Liang
authors.affiliation: Florey Institute of Neuroscience and Mental Health, Melbourne, Victoria, Australia; Florey Department of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia; Department of Medicine, Austin Health and Northern Health, University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Fernando
authors.initials: F
authors.lastname: Calamante
authors.affiliation: Florey Institute of Neuroscience and Mental Health, Melbourne, Victoria, Australia; Florey Department of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia; Department of Medicine, Austin Health and Northern Health, University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Alan
authors.initials: A
authors.lastname: Connelly
mesh_terms: D000328:Adult; D001921:Brain / Q000000981:diagnostic imaging*; D063132:Connectome / Q000379:methods*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008297:Male; D009413:Nerve Fibers, Myelinated
keywords: Diffusion MRI; Fibre-tracking; Network metrics; Structural connectome; Tractography