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Acute focal cerebral ischemia in rats studied by diffusion-weighted magnetic resonance imaging--an experimental study
R Kimura1, A Shiino, M Matsuda
1Department of Neurosurgery, Shiga University of Medical Science, Japan.
Background:
Temporary occlusion of the cerebral artery is occasionally repeated during neurosurgical operations, but the safety of such a procedure remains to be studied further.
Method:
We studied early changes and reversibility of focal cerebral ischemia and the cumulative effects of repeated ischemic insults in rats using magnetic resonance imaging (MRI).
Results:
Diffusion-weighted magnetic resonance images (DWI) and determination of signal intensity ratio (SIR) proved to be a valuable measure of studying early changes and reversibility of transient focal cerebral ischemia and cumulative adverse effects of repeated ischemic insults. DWIs showed marked intensity changes shortly after focal cerebral ischemia, while T2-weighted images failed to show hyperintensities until 2.5 hours after the onset of permanent ischemia. The critical period of ischemia in this model was 60 minutes. However, 20 minutes ischemia, when repeated twice with 60 minutes reperfusion in between, showed irreversible damage.
Conclusion:
Repeated insults of focal regional cerebral ischemia may cause irreversible tissue damage even if each ischemic period is less than the critical one.
Insights
Repeated temporary cerebral artery occlusion can cause irreversible damage, even if each event is brief. This study highlights the cumulative risks of repeated focal cerebral ischemia in neurosurgery.
Area of Science:
- Neurology
- Neurosurgery
- Medical Imaging
Background:
- Temporary cerebral artery occlusion is used in neurosurgery.
- The safety of repeated occlusion is not well understood.
Purpose of the Study:
- To investigate early changes and reversibility of focal cerebral ischemia.
- To assess cumulative effects of repeated ischemic insults.
Main Methods:
- Used magnetic resonance imaging (MRI) in a rat model.
- Employed diffusion-weighted images (DWI) and signal intensity ratio (SIR).
Main Results:
- DWI effectively detected early ischemic changes and reversibility.
- 20-minute ischemia, repeated twice with reperfusion, caused irreversible damage.
- T2-weighted images showed hyperintensities later than DWI.
Conclusions:
- Repeated focal cerebral ischemia can lead to irreversible tissue damage.
- Even short ischemic periods, when repeated, may exceed the critical threshold.