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Updated: Oct 3, 2026
Simultaneous PET/MRI Imaging During Mouse Cerebral Hypoxia-ischemia
Published on: September 20, 2015
Diffusion-weighted MR imaging of acute stroke: correlation with T2-weighted and magnetic susceptibility-enhanced MR
M E Moseley1, J Kucharczyk, J Mintorovitch
1Department of Radiology, University of California, San Francisco 94143.
Abstract:
We evaluated the temporal and anatomic relationships between changes in diffusion-weighted MR image signal intensity, induced by unilateral occlusion of the middle cerebral artery in cats, and tissue perfusion deficits observed in the same animals on T2-weighted MR images after administration of a nonionic intravascular T2 shortening agent. Diffusion-weighted images obtained with strong diffusion-sensitizing gradient strengths (5.6 gauss/cm, corresponding to gradient attenuation factor, b, values of 1413 sec/mm2) displayed increased signal intensity in the ischemic middle cerebral artery territory less than 1 hr after occlusion, whereas T2-weighted images without contrast usually failed to detect injury for 2-3 hr after stroke. After contrast administration (0.5-1.0 mmol/kg by Dy-DTPA-BMA, IV), however, T2-weighted images revealed perfusion deficits (relative hyperintensity) within 1 hr after middle cerebral artery occlusion that corresponded closely to the anatomic regions of ischemic injury shown on diffusion-weighted MR images. Close correlations were also found between early increases in diffusion-weighted MR image signal intensity and disrupted phosphorus-31 and proton metabolite levels evaluated with surface coil MR spectroscopy, as well as with postmortem histopathology. These data indicate that diffusion-weighted MR images more accurately reflect early-onset pathophysiologic changes induced by acute cerebral ischemia than do T2-weighted spin-echo images.
Insights
Diffusion-weighted MRI detects acute ischemic stroke earlier than T2-weighted MRI. This technique accurately maps brain injury within an hour of middle cerebral artery occlusion, correlating with metabolic changes and pathology.
Area of Science:
- Neuroimaging
- Medical Physics
- Stroke Research
Background:
- Acute ischemic stroke diagnosis relies on timely and accurate imaging.
- Conventional T2-weighted MRI often shows delayed detection of ischemic injury.
- Diffusion-weighted MRI (DW-MRI) shows promise for early stroke detection.
Purpose of the Study:
- To compare the temporal and anatomic accuracy of DW-MRI and contrast-enhanced T2-weighted MRI in detecting acute ischemic stroke.
- To evaluate the correlation of early MRI findings with metabolic changes and histopathology.
Main Methods:
- Unilateral middle cerebral artery occlusion was induced in feline models.
- Diffusion-weighted MRI and T2-weighted MRI (with and without contrast agent Dy-DTPA-BMA) were performed.
- MR spectroscopy and postmortem histopathology were used for correlation.
Main Results:
- DW-MRI detected increased signal intensity in the ischemic territory within 1 hour of occlusion.
- Contrast-enhanced T2-weighted MRI revealed perfusion deficits within 1 hour, closely matching DW-MRI findings.
- Non-contrast T2-weighted MRI typically failed to detect injury for 2-3 hours.
- Early DW-MRI signal changes correlated with metabolic disruptions and histopathological findings.
Conclusions:
- Diffusion-weighted MRI is superior to conventional T2-weighted MRI for early detection of acute cerebral ischemia.
- Contrast-enhanced T2-weighted MRI can provide complementary information on perfusion deficits.
- DW-MRI accurately reflects early pathophysiological changes in acute ischemic stroke.
