Related Experiment Videos
Correlation of sequential MR images of microsphere-induced cerebral ischemia with histologic changes in rats
K Fukuchi1, H Kusuoka, Y Watanabe
1Division of Tracer Kinetics, Biomedical Research Center, Osaka University Medical School, Suita, Japan.
Objective:
To determine the time course of changes in MRI findings of multiple cerebral microembolism, the authors induced experimental multiple microinfarctions in rats using microspheres and then examined sequential MRI and histopathologic findings. The authors also evaluated how the amount of injected embolic materials affected the findings.
Methods:
The authors injected 25-microm microspheres (range, 2000-8000 gm) into the unilateral internal carotid arteries of rats. The animals were assessed by MRI and histopathology at 1 day or 8 days after embolization.
Results:
One day after embolization, multiple high-intensity areas on T2-weighted images were related to the number of injected microspheres and were associated with regions of cerebral edema on histopathologic specimens. On day 8, the high-intensity areas on T2-weighted images observed on day 1 were markedly diminished in the groups receiving up to 6000 microspheres. In the group injected with 8000 microspheres, however, the high-intensity areas were less diminished, and these areas were significantly larger than in the other groups (P < 0.05).
Conclusions:
The MRI features of cerebral ischemia or infarction induced by microsphere embolism vary depending on the number of injected microspheres. Recovery from acute cerebral embolism has a threshold based on ischemic cell volume.
Insights
Experimental cerebral microembolism in rats shows that MRI findings depend on microsphere quantity. Recovery from acute cerebral embolism has a threshold related to ischemic cell volume, impacting T2-weighted image intensity.
Area of Science:
- Neuroscience
- Radiology
- Pathology
Background:
- Cerebral microembolism is a significant cause of stroke.
- Understanding the evolution of MRI findings is crucial for diagnosis and treatment.
- Experimental models are essential for studying the pathophysiology of cerebral microinfarction.
Purpose of the Study:
- To investigate the temporal changes in MRI findings following induced multiple cerebral microinfarctions in rats.
- To correlate MRI observations with histopathological findings.
- To assess the impact of embolic material quantity on MRI characteristics and outcomes.
Main Methods:
- Induction of experimental multiple cerebral microinfarctions in rats using 25-microm microspheres.
- Administration of varying quantities of microspheres (2000-8000) into the unilateral internal carotid artery.
- Sequential assessment using magnetic resonance imaging (MRI) and histopathology at 1 and 8 days post-embolization.
Main Results:
- One day post-embolization, T2-weighted MRI showed high-intensity areas corresponding to cerebral edema, with intensity related to microsphere number.
- By day 8, high-intensity areas diminished in rats receiving up to 6000 microspheres.
- Rats receiving 8000 microspheres exhibited less diminished high-intensity areas, which were significantly larger than in other groups.
Conclusions:
- MRI features of microsphere-induced cerebral ischemia/infarction are dose-dependent.
- Recovery from acute cerebral embolism is influenced by a threshold related to the volume of ischemic cells.
- These findings highlight the utility of MRI in evaluating the extent and resolution of experimental cerebral microembolism.