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Histopathologic correlates of abnormal water diffusion in cerebral ischemia: diffusion-weighted MR imaging and light
C Pierpaoli1, A Righini, I Linfante
1Neuroimaging Branch, National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, MD 20892.
Purpose:
To correlate the findings on diffusion-weighted magnetic resonance (MR) images with the cytologic and histologic findings in ischemic tissue.
Materials And Methods:
A photochemical model of cerebral infarction in rats was studied with diffusion- and T2-weighted MR imaging. The development of lesions was followed from 20 minutes to 5 days after the onset of ischemia. Apparent water diffusion coefficient (ADC) maps were calculated and correlated with light and electron microscopic findings.
Results:
T2-weighted images clearly showed vasogenic edema but did not enable distinction between areas with cellular damage and the surrounding edematous regions. In contrast, the ADC, which was elevated in nonischemic edematous regions, was diminished in areas with histologic evidence of ischemic damage or necrosis. In the core of the infarct, the ADC became elevated when electron microscopy revealed cellular lysis.
Conclusion:
Diffusion-weighted images may help ascertain the extent of cellular damage and death after stroke.
Insights
Diffusion-weighted MRI can distinguish ischemic damage from edema in stroke models. Apparent diffusion coefficient (ADC) mapping reveals areas of cellular damage and necrosis, aiding in stroke assessment.
Area of Science:
- Neuroimaging
- Stroke Research
- Cellular Pathology
Background:
- Ischemic stroke causes cellular damage and edema.
- Distinguishing between edema and cellular damage is crucial for stroke assessment.
- Diffusion-weighted magnetic resonance (MR) imaging offers potential for in vivo tissue characterization.
Purpose of the Study:
- To correlate diffusion-weighted MR imaging findings with cytologic and histologic findings in ischemic tissue.
- To evaluate the utility of apparent water diffusion coefficient (ADC) maps in identifying ischemic damage.
- To assess the temporal evolution of lesions in a rat model of cerebral infarction.
Main Methods:
- A photochemical model of cerebral infarction was induced in rats.
- Diffusion- and T2-weighted MR imaging was performed serially from 20 minutes to 5 days post-ischemia.
- Apparent water diffusion coefficient (ADC) maps were calculated and correlated with light and electron microscopy.
Main Results:
- T2-weighted images showed vasogenic edema but could not differentiate cellular damage.
- ADC was elevated in nonischemic edema but diminished in areas of ischemic damage and necrosis.
- In the infarct core, ADC increased with cellular lysis observed via electron microscopy.
Conclusions:
- Diffusion-weighted imaging, particularly ADC mapping, can help ascertain the extent of cellular damage and death after stroke.
- This technique may improve the diagnostic accuracy and prognostic assessment of ischemic stroke.
- The findings support the use of diffusion-weighted MRI in preclinical stroke research.