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Updated: Jun 2, 2026
Simultaneous PET/MRI Imaging During Mouse Cerebral Hypoxia-ischemia
Published on: September 20, 2015
Stroke penumbra defined by an MRI-based oxygen challenge technique: 1. Validation using [14C]2-deoxyglucose
Craig A Robertson1, Christopher McCabe, Lindsay Gallagher
1Glasgow Experimental MRI Centre, Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK. c.robertson.1@research.gla.ac.uk
Abstract:
Accurate identification of ischemic penumbra will improve stroke patient selection for reperfusion therapies and clinical trials. Current magnetic resonance imaging (MRI) techniques have limitations and lack validation. Oxygen challenge T(2)(*) MRI (T(2)(*) OC) uses oxygen as a biotracer to detect tissue metabolism, with penumbra displaying the greatest T(2)(*) signal change during OC. [(14)C]2-deoxyglucose (2-DG) autoradiography was combined with T(2)(*) OC to determine metabolic status of T(2)(*)-defined penumbra. Permanent middle cerebral artery occlusion was induced in anesthetized male Sprague-Dawley rats (n=6). Ischemic injury and perfusion deficit were determined by diffusion- and perfusion-weighted imaging, respectively. At 147 ± 32 minutes after stroke, T(2)(*) signal change was measured during a 5-minute 100% OC, immediately followed by 125 microCi/kg 2-DG, intravenously. Magnetic resonance images were coregistered with the corresponding autoradiograms. Regions of interest were located within ischemic core, T(2)(*)-defined penumbra, equivalent contralateral structures, and a region of hyperglycolysis. A T(2)(*) signal increase of 9.22% ± 3.9% (mean ± s.d.) was recorded in presumed penumbra, which displayed local cerebral glucose utilization values equivalent to contralateral cortex. T(2)(*) signal change was negligible in ischemic core, 3.2% ± 0.78% in contralateral regions, and 1.41% ± 0.62% in hyperglycolytic tissue, located outside OC-defined penumbra and within the diffusion abnormality. The results support the utility of OC-MRI to detect viable penumbral tissue following stroke.
Insights
Oxygen challenge T(2)(*) MRI detects viable brain tissue (penumbra) after stroke. This method, validated with [14C]2-deoxyglucose, shows promise for improving patient selection for stroke therapies.
Area of Science:
- Neuroimaging
- Stroke Research
- Metabolic Imaging
Background:
- Accurate identification of the ischemic penumbra is crucial for selecting stroke patients for reperfusion therapies and clinical trials.
- Current magnetic resonance imaging (MRI) techniques for penumbra detection have limitations and lack validation.
- Oxygen challenge T(2)(*) MRI (T(2)(*) OC) utilizes oxygen as a biotracer to assess tissue metabolism, with the penumbra exhibiting the most significant T(2)(*) signal change during OC.
Purpose of the Study:
- To validate the utility of T(2)(*) OC MRI in identifying viable penumbral tissue.
- To correlate T(2)(*) signal changes during oxygen challenge with local cerebral glucose utilization.
- To compare T(2)(*) OC findings with established measures of ischemic injury and perfusion deficit.
Main Methods:
- Permanent middle cerebral artery occlusion was induced in rats.
- T(2)(*) signal change was measured during a 5-minute 100% oxygen challenge (OC) after stroke induction.
- [14C]2-deoxyglucose (2-DG) autoradiography was performed immediately after OC to assess local cerebral glucose utilization.
- MRI data were coregistered with autoradiograms to analyze metabolic status within T(2)(*)-defined regions.
Main Results:
- A significant T(2)(*) signal increase (9.22% ± 3.9%) was observed in the presumed penumbra during OC.
- The T(2)(*) penumbra demonstrated local cerebral glucose utilization comparable to the contralateral cortex.
- Negligible T(2)(*) signal changes were noted in the ischemic core, contralateral regions, and hyperglycolytic tissue outside the OC-defined penumbra.
Conclusions:
- Oxygen challenge T(2)(*) MRI effectively detects metabolically active penumbral tissue following stroke.
- This technique shows potential for improving the selection of patients for reperfusion therapies and clinical trials.
- T(2)(*) OC MRI offers a validated, non-invasive method for assessing penumbra viability.
