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Diffusion-weighted magnetic resonance imaging: rapid and quantitative detection of focal brain ischemia
1Department of Neurology, Medical Center of Central Massachusetts, Worcester 01605.
Abstract:
We examined serial changes of diffusion- (DWI) and T2-weighted (T2WI) magnetic resonance images 30 minutes to 3 hours after intraluminal suture occlusion of the middle cerebral artery (MCA) in eight rats and after sham occlusion in four. We correlated the abnormal areas on DWI and T2WI with postmortem areas of infarction determined by 2,3,5-triphenyltetrazolium chloride (TTC), 24 hours after the operation. The 30-minute DWI in each MCA-occluded rat demonstrated increased signal intensity in the ipsilateral MCA territory, while T2WI showed no changes. At 3 hours, the ipsilateral DWI signal intensity increased further and the area of abnormality slightly increased. In some animals, the 3-hour T2WI disclosed an area of hyperintensity significantly smaller than that seen on the 30-minute DWI. TTC staining demonstrated an extensive MCA infarction in all rats with permanent MCA occlusion, confirmed by hematoxylin and eosin staining. The percent infarcted area of coronal brain sections, as determined by TTC staining, correlated significantly with areas on similar DWI sections at both 30 minutes and 3 hours. Sham-occluded control animals did not display any changes on DWI, T2WI, or TTC staining. The present study suggests that DWI is a very sensitive modality for detecting early ischemic brain injury, being highly correlated with post-mortem area of infarction, and may be useful to assess pharmacologic intervention.
Insights
Diffusion-weighted imaging (DWI) detects early ischemic stroke in rats within 30 minutes, showing high correlation with infarction size. This sensitive MRI technique aids in assessing potential stroke treatments.
Area of Science:
- Neurology
- Radiology
- Neuroimaging
Background:
- Stroke is a leading cause of death and disability worldwide.
- Early detection of ischemic stroke is crucial for effective treatment.
- Magnetic resonance imaging (MRI) techniques like DWI and T2WI are used to diagnose stroke.
Purpose of the Study:
- To evaluate the sensitivity of diffusion-weighted imaging (DWI) and T2-weighted imaging (T2WI) in detecting early ischemic brain injury.
- To correlate MRI findings with postmortem infarction areas.
- To assess the potential of DWI in evaluating therapeutic interventions for stroke.
Main Methods:
- Serial DWI and T2WI were performed on rats 30 minutes to 3 hours after middle cerebral artery (MCA) occlusion.
- Sham-occluded rats served as controls.
- Postmortem infarction was assessed using 2,3,5-triphenyltetrazolium chloride (TTC) staining and confirmed with hematoxylin and eosin staining.
Main Results:
- DWI showed increased signal intensity in the MCA territory within 30 minutes of occlusion, while T2WI showed no changes.
- At 3 hours, DWI abnormalities increased, and T2WI showed smaller hyperintense areas in some rats.
- TTC staining confirmed extensive infarction, and the infarcted area correlated significantly with DWI findings at both 30 minutes and 3 hours.
Conclusions:
- DWI is a highly sensitive method for early detection of ischemic brain injury.
- DWI findings correlate well with the extent of postmortem infarction.
- DWI may be a valuable tool for assessing the efficacy of pharmacological interventions in stroke treatment.