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Updated: Jan 12, 2026
A Magnetic Resonance Imaging Protocol for Stroke Onset Time Estimation in Permanent Cerebral Ischemia
Published on: September 16, 2017
Detection of the anoxic depolarization of focal ischemia using manganese-enhanced MRI
Ichio Aoki1, Toshihiko Ebisu, Chuzo Tanaka
1Department of Neurosurgery, Meiji University of Oriental Medicine, Kyoto, Japan. aoki@muom.meiji-u.ac.jp
Abstract:
Mismatch between diffusion- and perfusion-weighted MRI was used to indicate a treatable area following focal ischemia, called the penumbra. Activity-induced manganese contrast MRI has been reported as a new visualization method for neural activation using manganese ions as a depolarization-dependent contrast agent. It is well known that energy failure induced by cerebral ischemia produces anoxic depolarization. The purpose of this study was to detect manganese accumulation caused by permanent middle cerebral artery occlusion (MCAO) of rat brain and to compare regional differences between manganese accumulation and decreased apparent diffusion coefficient (ADC). The ratios of signal intensity of manganese-enhanced MRI in the ipsilateral cortex to that in the contralateral cortex were 171.0 +/- 17.5% in MCAO group and 108.4 +/- 13.2% in the sham group. In addition, the enhanced region was much smaller than the area which was detected as having a reduced ADC.
Insights
This study shows that manganese-enhanced MRI can detect brain changes after stroke, but the manganese accumulation area is smaller than the diffusion-weighted MRI area, suggesting it may highlight a specific treatable region.
Area of Science:
- Neuroimaging
- Cerebrovascular disease
- Ischemic stroke
Background:
- Diffusion- and perfusion-weighted MRI identify the ischemic penumbra, a treatable area after stroke.
- Activity-induced manganese contrast MRI visualizes neural activation using manganese ions as a depolarization-dependent contrast agent.
- Cerebral ischemia leads to energy failure and anoxic depolarization.
Purpose of the Study:
- To detect manganese accumulation in rat brains following permanent middle cerebral artery occlusion (MCAO).
- To compare regional differences between manganese accumulation and decreased apparent diffusion coefficient (ADC).
Main Methods:
- Permanent middle cerebral artery occlusion (MCAO) in rats.
- Manganese-enhanced MRI to detect manganese accumulation.
- Diffusion-weighted MRI to measure apparent diffusion coefficient (ADC).
Main Results:
- Manganese-enhanced MRI showed significant signal intensity ratios in the ipsilateral cortex of MCAO rats (171.0 +/- 17.5%) compared to sham groups (108.4 +/- 13.2%).
- The region of manganese enhancement was notably smaller than the area identified with a reduced ADC.
Conclusions:
- Manganese accumulation occurs in response to permanent MCAO.
- Manganese-enhanced MRI may delineate a specific, potentially smaller, area within the larger diffusion-restricted region after stroke.
