title: Age-related microstructural differences quantified using myelin water imaging and advanced diffusion MRI.
abstract: Age-related microstructural differences have been detected using diffusion tensor imaging (DTI). Although DTI is sensitive to the effects of aging, it is not specific to any underlying biological mechanism, including demyelination. Combining multiexponential T2 relaxation (MET2) and multishell diffusion MRI (dMRI) techniques may elucidate such processes. Multishell dMRI and MET2 data were acquired from 59 healthy participants aged 17-70 years. Whole-brain and regional age-associated correlations of measures related to multiple dMRI models (DTI, diffusion kurtosis imaging [DKI], neurite orientation dispersion and density imaging [NODDI]) and myelin-sensitive MET2 metrics were assessed. DTI and NODDI revealed widespread increases in isotropic diffusivity with increasing age. In frontal white matter, fractional anisotropy linearly decreased with age, paralleled by increased "neurite" dispersion and no difference in myelin water fraction. DKI measures and neurite density correlated well with myelin water fraction and intracellular and extracellular water fraction. DTI estimates remain among the most sensitive markers for age-related alterations in white matter. NODDI, DKI, and MET2 indicate that the initial decrease in frontal fractional anisotropy may be due to increased axonal dispersion rather than demyelination.
authors.affiliation: Translational MRI, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium; Department of Radiology, University Hospitals Leuven, Leuven, Belgium; Medical Imaging Research Center (MIRC), Leuven, Belgium; Leuven Research Institute for Neuroscience & Disease (LIND), Leuven, Belgium. Electronic address: Thibo.billiet@uzleuven.be.
authors.forename: Thibo
authors.initials: T
authors.lastname: Billiet
authors.affiliation: Leuven Research Institute for Neuroscience & Disease (LIND), Leuven, Belgium; Department of Old Age Psychiatry, KU Leuven, Leuven, Belgium.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Vandenbulcke
authors.affiliation: Philips Healthcare, Hamburg, Germany; Department of Neurosurgery, Medical Centre, University of Bonn, Bonn, Germany.
authors.forename: Burkhard
authors.initials: B
authors.lastname: Mädler
authors.affiliation: Department of Radiology, University Hospitals Leuven, Leuven, Belgium; Leuven Research Institute for Neuroscience & Disease (LIND), Leuven, Belgium.
authors.forename: Ronald
authors.initials: R
authors.lastname: Peeters
authors.affiliation: Medical Imaging Research Center (MIRC), Leuven, Belgium; The Florey Institute of Neuroscience and Mental Health, Melbourne, Victoria, Australia.
authors.forename: Thijs
authors.initials: T
authors.lastname: Dhollander
authors.affiliation: Department of Computer Science, University College London, London, UK; Centre for Medical Image Computing, University College London, London, UK.
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Translational MRI, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium; Department of Radiology, University Hospitals Leuven, Leuven, Belgium; Medical Imaging Research Center (MIRC), Leuven, Belgium; Leuven Research Institute for Neuroscience & Disease (LIND), Leuven, Belgium.
authors.forename: Sabine
authors.initials: S
authors.lastname: Deprez
authors.affiliation: Department of Developmental Psychology, Tilburg University, Tilburg, The Netherlands; Department of Psychology, KU Leuven, Leuven, Belgium.
authors.forename: Bea R H
authors.initials: BR
authors.lastname: Van den Bergh
authors.affiliation: Translational MRI, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium; Department of Radiology, University Hospitals Leuven, Leuven, Belgium; Medical Imaging Research Center (MIRC), Leuven, Belgium; Leuven Research Institute for Neuroscience & Disease (LIND), Leuven, Belgium.
authors.forename: Stefan
authors.initials: S
authors.lastname: Sunaert
authors.affiliation: Translational MRI, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium; Department of Radiology, University Hospitals Leuven, Leuven, Belgium; Medical Imaging Research Center (MIRC), Leuven, Belgium; Leuven Research Institute for Neuroscience & Disease (LIND), Leuven, Belgium; Department of Old Age Psychiatry, KU Leuven, Leuven, Belgium.
authors.forename: Louise
authors.initials: L
authors.lastname: Emsell
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000473:pathology*; D016880:Anisotropy; D001369:Axons / Q000473:pathology; D001921:Brain / Q000473:pathology*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016501:Neurites / Q000473:pathology; D066127:White Matter / Q000473:pathology; D055815:Young Adult
keywords: Aging; Diffusion MRI; Healthy; Kurtosis; Myelin water imaging; Relaxometry