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Temporal evolution and spatial distribution of the diffusion constant of water in rat brain after transient middle
Abstract:
The regional distribution and temporal evolution of the diffusion coefficient (Dw) of water in rat brain was measured during and after transient middle cerebral artery (MCA) occlusion. Male Wistar rats (n = 14) were subjected to 2 h of middle cerebral artery occlusion, induced by intracarotid insertion of a filament. Diffusion (n = 14) and perfusion (n = 7) weighted magnetic resonance imaging were performed before, and at various time points after MCA occlusion, ranging from 30 min up to 7 days. Our data demonstrate that the temporal profiles of Dw differ between the severely and the least damaged regions of tissue. In the core of the lesion, where the tissue evolved to necrosis, Dw declined significantly (P < 0.001) within 0.5 h after onset of ischemia, and remained depressed until 24 h after withdrawal of the suture. However, no statistically significant decline in Dw was found in the perifocal regions containing morphologically intact cells. Perfusion MRI qualitatively exhibited a hypoperfusion and reperfusion during, and after 2 h MCA occlusion, respectively. A significant (r > or = 0.71, P < 0.01) correlation was found between delta Dw (the difference in Dw between the ipsilateral ischemic and homologous contralateral control regions) obtained immediately before withdrawal of the suture (2 h of ischemia) and at specific early time points after withdrawal of the suture, and the degree of ischemic cell damage. No significant (P > 0.01) correlation was detected at an early time points of ischemia or at other time points after withdrawal of the suture.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Diffusion MRI reveals water diffusion coefficient changes in rat brain during middle cerebral artery occlusion. A significant decline in the ischemic core predicts cell damage, aiding stroke outcome assessment.
Area of Science:
- Neuroscience
- Biomedical Imaging
- Stroke Research
Background:
- Transient middle cerebral artery (MCA) occlusion is a model for ischemic stroke.
- Understanding water diffusion changes is crucial for assessing brain tissue damage.
Purpose of the Study:
- To investigate the regional and temporal changes in the water diffusion coefficient (Dw) in rat brain during and after MCA occlusion.
- To correlate diffusion changes with the degree of ischemic cell damage.
Main Methods:
- Male Wistar rats underwent 2-hour MCA occlusion.
- Diffusion and perfusion-weighted magnetic resonance imaging (MRI) were performed at various time points.
- Correlation analysis was used to link diffusion changes with cell damage.
Main Results:
- Dw significantly declined in the ischemic core within 0.5 hours, persisting for 24 hours post-occlusion.
- No significant Dw decline was observed in perifocal regions with intact cells.
- A strong correlation was found between Dw changes and ischemic cell damage early after occlusion.
Conclusions:
- Temporal Dw profiles differ between severely damaged and less damaged brain regions.
- Early Dw changes, particularly delta Dw, are predictive of ischemic cell damage severity.
- Diffusion MRI is a valuable tool for monitoring stroke progression and predicting outcomes.