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Changes in white matter microstructural integrity across the early subacute, late subacute and chronic stages of stroke recovery: a longitudinal diffusion-weighted MRI study
Poster Session A - Sandbox Series, Thursday, October 24, 10:00 - 11:30 am, Great Hall 3 and 4
This poster is part of the Sandbox Series.
Viktoriia Pozdniakova1,2, Stephen Wilson1, Katie McMahon3,4, David Copland1,2, Sonia Brownsett1,2; 1School of Health and Rehabilitation Sciences, The University of Queensland, 2Queensland Aphasia Research Centre, The University of Queensland, 3Herston Imaging Research Facility, 4School of Clinical Sciences, Queensland University of Technology
In aphasia rehabilitation, it is widely accepted that the most significant improvements occur within the first three months following a stroke. After this period, recovery becomes less pronounced and depends on various factors, including lesion site and size, and initial impairment severity [1]. Reduced microstructural integrity of the white-matter tracts involved in language processing is commonly observed in post-stroke aphasia. However, findings regarding changes in white matter connectivity across the course of aphasia recovery have been inconsistent [e.g., 2,3]. In this sandbox series presentation, we describe our project in progress aiming to evaluate changes in structural connectivity across the stroke recovery trajectory. We are conducting a longitudinal diffusion-weighted MRI study with a cohort of stroke survivors. In total, 34 participants have been recruited (28.4 ± 9.3 days post-onset), 18 of whom underwent follow-up screening and imaging at the late subacute stage (96.8 ± 8.8 days post-onset), and 29 at the chronic stage (205.7 ± 17.4 days post-onset). We also recruited a control group of 39 age- and sex-matched healthy participants. Tracts of interest will be mapped with an automatic fibre-tracking algorithm in DSI Studio [4]. The following metrics of microstructural integrity will be derived: quantitative anisotropy (QA), i.e., the degree of anisotropy of water diffusion in the tract; axial diffusivity (AD), i.e., the magnitude of diffusion parallel to the tract; radial diffusivity (RD), i.e., the magnitude of diffusion perpendicular to the tract; and the mean diffusion (MD), i.e., the mean amount of diffusion in a voxel. We will evaluate: (1) these metrics in the clinical group, in comparison to the control group; (2) differences between the diffusion metrics in the left hemisphere, compared to the intact right hemisphere; and (3) changes in diffusion metrics across the early subacute to late subacute to chronic stages of stroke rehabilitation. We hypothesise that: (1) at the early subacute stage, QA values will be decreased in the left hemisphere tracts of those with post-stroke aphasia compared to healthy controls, due to the stroke-induced disruption of white matter integrity; (2) QA values will be decreased in left hemisphere tracts compared to the intact right hemisphere; and (3) the differences in diffusion metrics observed between groups and hemispheres will change over the course of recovery, reflecting axonal degeneration along with potential neuroplastic changes. Our findings will contribute to a better understanding of the mechanisms and time course of structural connectivity changes in recovery from aphasia after stroke. References 1. Pedersen et al., Ann Neurol 1995;38(4):659–666. 2. Bae et al., Neurorehabil Neural Repair 2022;36(9):633–644. 3. van Hees et al., Neurorehabil Neural Repair 2014;28(4):325–334. 4. Yeh, DSI Studio (2021) [Computer software]. Zenodo.
Topic Areas: Disorders: Acquired,