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Longitudinal evolution of diffusion metrics after left hemisphere ischaemic stroke
Johémie Boucher1,2, Karine Marcotte3,4, Christophe Bedetti1,2
1Department of Psychology, Centre de recherche de l'Institut Universitaire de Gériatrie de Montréal, Montréal, QC H3W 1W5, Canada.
Brain Communications
|December 11, 2023
Summary
This study shows how white matter changes over time after ischemic stroke using MRI. Different diffusion metrics reveal distinct injury patterns in the lesion and surrounding areas during recovery.
Area of Science:
- Neuroimaging
- Stroke Research
- White Matter Integrity
Background:
- White matter damage is a significant consequence of ischemic stroke.
- Mechanisms of white matter injury post-stroke in humans are not fully understood.
- Longitudinal characterization of white matter changes is crucial for understanding stroke recovery.
Purpose of the Study:
- To longitudinally describe the evolution of diffusion magnetic resonance imaging metrics in ipsilesional white matter after ischemic stroke.
- To characterize the distinct patterns of white matter damage in the lesion, perilesional, and remote areas.
- To elucidate the underlying physiological processes contributing to white matter injury at different stroke stages.
Main Methods:
- Acquired diffusion and anatomical MRI in 17 patients with left hemisphere ischemic stroke at acute, subacute, and chronic stages.
- Defined regions of interest: white matter lesion, perilesional white matter, and remaining white matter.
- Analyzed diffusion metrics (fractional anisotropy, mean, axial, radial diffusivities) using repeated measures ANOVA.
Main Results:
- Fractional anisotropy was consistently lower in the white matter lesion and perilesional white matter compared to remote white matter.
- Mean, axial, and radial diffusivities decreased acutely in the lesion but increased significantly in subacute and chronic stages.
- Perilesional white matter showed increased mean and radial diffusivities in later stages.
Conclusions:
- Ischemic stroke induces complex, time-dependent changes in white matter integrity.
- Diffusion metrics reveal distinct pathophysiological processes (e.g., swelling, axonal damage, myelin loss) in different white matter compartments over time.
- Understanding these longitudinal changes is key to informing stroke recovery and treatment strategies.
