title: Quantitative Analysis of Myelin and Axonal Remodeling in the Uninjured Motor Network After Stroke.
abstract: Contralesional brain connectivity plasticity was previously reported after stroke. This study aims at disentangling the biological mechanisms underlying connectivity plasticity in the uninjured motor network after an ischemic lesion. In particular, we measured generalized fractional anisotropy (GFA) and magnetization transfer ratio (MTR) to assess whether poststroke connectivity remodeling depends on axonal and/or myelin changes. Diffusion-spectrum imaging and magnetization transfer MRI at 3T were performed in 10 patients in acute phase, at 1 and 6 months after stroke, which was affecting motor cortical and/or subcortical areas. Ten age- and gender-matched healthy volunteers were scanned 1 month apart for longitudinal comparison. Clinical assessment was also performed in patients prior to magnetic resonance imaging (MRI). In the contralesional hemisphere, average measures and tract-based quantitative analysis of GFA and MTR were performed to assess axonal integrity and myelination along motor connections as well as their variations in time. Mean and tract-based measures of MTR and GFA showed significant changes in a number of contralesional motor connections, confirming both axonal and myelin plasticity in our cohort of patients. Moreover, density-derived features (peak height, standard deviation, and skewness) of GFA and MTR along the tracts showed additional correlation with clinical scores than mean values. These findings reveal the interplay between contralateral myelin and axonal remodeling after stroke.
authors.affiliation: 1 Department of Computer Science, University of Verona , Verona, Italy .
authors.forename: Ying-Chia
authors.initials: YC
authors.lastname: Lin
authors.affiliation: 2 STI/IEL/LTS5 , Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland .
authors.forename: Alessandro
authors.initials: A
authors.lastname: Daducci
authors.affiliation: 3 Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland .|4 Department of Radiology and Medical Informatics, University of Geneva , Geneva, Switzerland .
authors.forename: Djalel Eddine
authors.initials: DE
authors.lastname: Meskaldji
authors.affiliation: 2 STI/IEL/LTS5 , Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland .
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Thiran
authors.affiliation: 5 Stroke Center, Department of Clinical Neurosciences, Centre Hospitalier Universitaire Vaudois, University of Lausanne , Lausanne, Switzerland .
authors.forename: Patrik
authors.initials: P
authors.lastname: Michel
authors.affiliation: 6 Department of Radiology, Centre Hospitalier Universitaire Vaudois, University of Lausanne , Lausanne, Switzerland .
authors.forename: Reto
authors.initials: R
authors.lastname: Meuli
authors.affiliation: 7 Healthcare Sector IM&WS S, Siemens Schweiz AG, Lausanne, Switzerland .|8 Advanced Clinical Imaging Technology Group, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland .
authors.forename: Gunnar
authors.initials: G
authors.lastname: Krueger
authors.affiliation: 1 Department of Computer Science, University of Verona , Verona, Italy .
authors.forename: Gloria
authors.initials: G
authors.lastname: Menegaz
authors.affiliation: 2 STI/IEL/LTS5 , Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland .|8 Advanced Clinical Imaging Technology Group, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland .|9 Laboratoire de Recherche en Neuroimagerie and Neuroimmunology Unit, Department of Clinical Neurosciences, Centre Hospitalier Universitaire Vaudois and University of Lausanne , Lausanne, Switzerland .
authors.forename: Cristina
authors.initials: C
authors.lastname: Granziera
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016880:Anisotropy; D001369:Axons / Q000473:pathology*; D001921:Brain / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009046:Motor Neurons / Q000473:pathology*; D009186:Myelin Sheath / Q000473:pathology*; D009415:Nerve Net / Q000473:pathology*; D011712:Pyramidal Tracts / Q000473:pathology; D020521:Stroke / Q000473:pathology*
keywords: diffusion-spectrum imaging; graph; longitudinal study; magnetization transfer ratio; stroke