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Updated: May 6, 2026
Author Spotlight: Assessing Ischemic Stroke Damage Through Middle Cerebral Artery Occlusion Model
Published on: August 11, 2023
Effects of cerebral ischemic and reperfusion on T2*-weighted MRI responses to brief oxygen challenge
Qiang Shen1, Fang Du2, Shiliang Huang2
11] Department of Research Imaging Institute, San Antonio, Texas, USA [2] Department of Ophthalmology, San Antonio, Texas, USA [3] Department of Radiology, University of Texas Health Science Center, San Antonio, Texas, USA.
Abstract:
This study characterized the effects of cerebral ischemia and reperfusion on T2*-weighted magnetic resonance image (MRI) responses to brief oxygen challenge (OC) in transient (60 minutes) cerebral ischemia in rats. During occlusion, the ischemic core tissue showed no significant OC response, whereas the perfusion-diffusion mismatch tissue showed markedly higher percent changes relative to normal tissue. After reperfusion, much of the pixels with initial exaggerated OC responses showed normal OC responses, and the majority of these tissues were salvaged as defined by endpoint T2 MRI. The initial core pixels showed exaggerated OC responses after reperfusion, but the majority of the core pixels eventually became infarct, suggesting exaggerated OC responses do not necessarily reflect salvageable tissue. Twenty-four hours after stroke, basal T1 increased in the ischemic core. Oxygen challenge decreased T1 significantly in the core, indicative of the substantial increases in dissolved oxygen in the core as the result of hyperperfusion. We concluded that exaggerated T2*-weighted MRI responses to OC offer useful insight in ischemic tissue fates. However, exaggerated OC pixels are not all salvageable, and they exhibited complex dynamics depending on reperfusion status, hyperperfusion, and edema effects.
Insights
This study used T2*-weighted MRI to assess oxygen challenge responses in rat stroke models. Exaggerated responses after reperfusion do not always indicate salvageable tissue, highlighting complex post-stroke dynamics.
Area of Science:
- Neuroscience
- Radiology
- Biomedical Engineering
Background:
- Cerebral ischemia and reperfusion injury are critical in stroke.
- T2*-weighted MRI and oxygen challenge (OC) offer insights into tissue viability.
- Understanding tissue fate post-stroke is crucial for therapeutic development.
Purpose of the Study:
- To characterize T2*-weighted MRI responses to OC in transient cerebral ischemia and reperfusion in rats.
- To investigate the relationship between OC responses and tissue salvage.
- To explore the dynamics of ischemic tissue fate after reperfusion.
Main Methods:
- Transient (60 minutes) cerebral ischemia was induced in rats.
- T2*-weighted MRI was used to assess responses to a brief oxygen challenge (OC).
- Perfusion-diffusion mismatch and ischemic core tissues were analyzed during and after reperfusion.
Main Results:
- During occlusion, ischemic core showed no significant OC response; mismatch tissue showed higher percent changes.
- After reperfusion, many initially exaggerated OC responses normalized, correlating with tissue salvage.
- However, initial exaggerated OC responses in the core did not guarantee salvage, with most becoming infarcts.
- Post-reperfusion, basal T1 increased in the ischemic core, decreasing significantly with OC due to hyperperfusion.
Conclusions:
- Exaggerated T2*-weighted MRI responses to OC provide valuable information on ischemic tissue fate.
- Not all tissues with exaggerated OC responses are salvageable, demonstrating complex dynamics.
- Tissue fate is influenced by reperfusion status, hyperperfusion, and edema effects.
Related Concept Videos
01:26Transient Ischemic Attack l: Introduction
01:15Ischemic Stroke ll: Pathophysiology
01:24Magnetic Resonance Imaging