Spatiotemporal microstructural white matter changes in diffusion tensor imaging after transient focal ischemic stroke...

Area of Science:

• Neuroscience
• Radiology
• Biomedical Engineering

Background:

• Stroke induces white matter (WM) reorganization, impacting brain function.
• Diffusion Tensor Imaging (DTI) assesses WM integrity and structural connectivity in vivo.
• Conventional DTI analysis methods have limitations in longitudinal studies.

Purpose of the Study:

• To investigate spatiotemporal WM changes after experimental focal ischemic stroke in rats using DTI.
• To evaluate the utility of tract-based spatial statistics (TBSS) for analyzing longitudinal DTI data post-stroke.
• To characterize the dynamic alterations in DTI parameters (FA, MD, DA, RD) during stroke recovery.

Main Methods:

• Experimental focal ischemic stroke was induced in rats (N=6).
• Longitudinal DTI data were acquired from 2 hours to 6 weeks post-stroke.
• Tract-based spatial statistics (TBSS) was employed to analyze DTI-derived parameters (FA, MD, DA, RD).
• Tractography was used to visualize fiber tract alterations.

Main Results:

• Fractional anisotropy (FA) remained stable initially, then decreased in the ipsilesional hemisphere from 24 hours to 2 weeks, followed by gradual recovery.
• Other DTI parameters (MD, DA, RD) exhibited complex early decreases, pseudo-normalization, and later increases.
• Fiber tracts showed extension towards the striatum in the ischemic boundary region at 6 weeks.

Conclusions:

• TBSS provides a reliable method for voxel-wise analysis of spatiotemporal WM changes post-stroke.
• The observed DTI parameter changes reflect ongoing tissue damage and spontaneous recovery processes.
• Findings highlight the dynamic nature of white matter reorganization following ischemic stroke.