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Updated: Jun 2, 2026
Measuring Post-Stroke Cerebral Edema, Infarct Zone and Blood-Brain Barrier Breakdown in a Single Set of Rodent Brain Samples
Published on: October 23, 2020
A biexponential DWI study in rat brain intracellular oedema
Roy Steier1, Mihály Aradi, József Pál
1Department of Neurosurgery, Faculty of Medicine University of Pécs, H-7623 Pécs, Rét street 2, Hungary. roy.steier@gmail.com
Purpose:
To examine the changes in MR parameters derived from diffusion weighted imaging (DWI) biexponential analysis in an in vivo intracellular brain oedema model, and to apply electron microscopy (EM) to shed more light on the morphological background of MR-related observations.
Materials And Methods:
Intracellular oedema was induced in ten male Wistar rats (380-450g) by way of water load, using a 20% body weight intraperitoneal injection of 140mmol/L dextrose solution. A 3T MRI instrument was used to perform serial DWI, and MR specroscopy (water signal) measurements. Following the MR examination the brains of the animals were analyzed for EM.
Results:
Following the water load induction, apparent diffusion coefficient (ADC) values started declining from 724±43μm(2)/s to 682±26μm(2)/s (p<0.0001). ADC-fast values dropped from 948±122 to 840±66μm(2)/s (p<0.001). ADC-slow showed a decrease from 226±66 to 191±74μm(2)/s (p<0.05). There was a shift from the slow to the fast component at 110min time point. The percentage of the fast component demonstrated moderate, yet significant increase from 76.56±7.79% to 81.2±7.47% (p<0.05). The water signal was increasing by 4.98±3.52% compared to the base line (p<0.01). The results of the E.M. revealed that water was detected intracellularly, within astrocytic preivascular end-feet and cell bodies.
Conclusion:
The unexpected volume fraction changes (i.e. increase in fast component) detected in hypotonic oedema appear to be substantially different from those observed in stroke. It may suggest that ADC decrease in stroke, in contrast to general presumptions, cannot be explained only by water shift from extra to intracellular space (i.e. intracellular oedema).
Insights
This study reveals that intracellular brain edema causes changes in diffusion-weighted imaging (DWI) parameters, differing from stroke models. These findings suggest stroke-related diffusion changes may involve more than just intracellular water shifts.
Area of Science:
- Neuroimaging
- Cellular Biology
- Medical Physics
Background:
- Intracellular brain edema is a critical condition affecting neuronal function.
- Diffusion-weighted imaging (DWI) is a key MRI technique for assessing water diffusion in the brain.
- Understanding the underlying morphological changes is crucial for interpreting DWI findings.
Purpose of the Study:
- To investigate alterations in MRI parameters from DWI biexponential analysis during induced intracellular brain edema.
- To correlate these MR findings with morphological changes observed via electron microscopy (EM).
Main Methods:
- Intracellular edema was induced in Wistar rats via intraperitoneal dextrose water load.
- Serial DWI and MR spectroscopy (water signal) were performed using a 3T MRI scanner.
- Brain tissue was subsequently analyzed using electron microscopy for morphological correlation.
Main Results:
- Apparent Diffusion Coefficient (ADC) values decreased significantly post-edema induction.
- A notable shift towards a faster diffusion component was observed, with a significant increase in its percentage.
- Electron microscopy confirmed intracellular water accumulation, particularly in astrocytic processes.
Conclusions:
- The observed changes in DWI parameters, specifically the increase in the fast diffusion component, differ from typical stroke-induced edema.
- These findings challenge the assumption that decreased ADC in stroke is solely due to intracellular water shift.
- The study highlights the complexity of water dynamics in different types of brain edema.
