Estimating intra-axonal axial diffusivity in the presence of fibre orientation dispersion
Estimating intra-axonal axial diffusivity in the presence of fibre orientation dispersion
Abstract By analysing the diffusion MRI signal, we can infer information about the microscopic structure of the brain. Two parameters of interest - the intra-axonal axial diffusivity and fibre orientation dispersion - are potential biomarkers for very different aspects of the white matter microstructure, yet they are difficult to disentangle. The parameters covary such that, if one is not accurately accounted for, the other will be biased. In this work we use high b-value data to isolate the signal from the intra-axonal compartment and resolve any degeneracies with the extra-axonal compartment. In the high b-value regime, we then use a model of dispersed sticks to estimate the intra-axonal axial diffusivity and fibre orientation distribution on a voxelwise basis. Our results in in vivo, human data show an intra-axonal axial diffusivity of ~ 2.3 – 3 μm2/ms, where 3 μm2/ms is the diffusivity of free water at 37°C. The intra-axonal axial diffusivity is seen to vary considerably across the white matter. For example, in the corpus callosum we find high values in the genu and splenium, and lower values in the midbody. Furthermore, the axial diffusivity and orientation dispersion appear negatively correlated, behaviour which we show is consistent with the presence of fibre undulations but not consistent with a degeneracy between fanning fibres and axial diffusivity. Finally, we demonstrate that the parameter maps output from Neurite Orientation Dispersion and Density Imaging (NODDI) change substantially when the assumed axial diffusivity was increased from 1.7 to 2.5 or 3 μm2/ms.
Howard Amy FD、Lange Frederik J、Jones Derek K、Mollink Jeroen、Jbabdi Saad、Umesh Rudrapatna Suryanarayana、Drakesmith Mark、Cottaar Michiel、Miller Karla L
FMRIB Centre, Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neurosciences, University of OxfordFMRIB Centre, Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neurosciences, University of OxfordCardiff University Brain Research Imaging Centre, Cardiff University||Neuroscience and Mental Health Research Institute, Cardiff University||Mary MacKillop Institute for Health Research, Faculty of Health Sciences, Australian Catholic UniversityFMRIB Centre, Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neurosciences, University of Oxford||Department of Anatomy, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre (Radboudumc)FMRIB Centre, Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neurosciences, University of OxfordCardiff University Brain Research Imaging Centre, Cardiff University||Philips Innovation CampusCardiff University Brain Research Imaging Centre, Cardiff University||Neuroscience and Mental Health Research Institute, Cardiff UniversityFMRIB Centre, Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neurosciences, University of OxfordFMRIB Centre, Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neurosciences, University of Oxford
基础医学生物科学研究方法、生物科学研究技术神经病学、精神病学
Howard Amy FD,Lange Frederik J,Jones Derek K,Mollink Jeroen,Jbabdi Saad,Umesh Rudrapatna Suryanarayana,Drakesmith Mark,Cottaar Michiel,Miller Karla L.Estimating intra-axonal axial diffusivity in the presence of fibre orientation dispersion[EB/OL].(2025-03-28)[2025-04-25].https://www.biorxiv.org/content/10.1101/2020.10.09.332700.点此复制
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