Perfusion and diffusion MR imaging of thromboembolic stroke

Area of Science:

• Neuroscience
• Radiology
• Biomedical Engineering

Background:

• Focal ischemia, a key aspect of stroke, involves complex physiological changes.
• Understanding these changes requires advanced imaging techniques to monitor blood flow and oxygenation.
• Magnetic resonance (MR) imaging offers non-invasive methods for assessing brain tissue.

Purpose of the Study:

• To investigate capillary blood deoxygenation during focal ischemia using MR imaging.
• To assess changes in apparent diffusion coefficient and tissue perfusion in a rat stroke model.
• To evaluate the effectiveness of a thrombolytic agent in restoring perfusion.

Main Methods:

• Utilized a carotid embolic stroke model in rats.
• Employed diffusion- and perfusion-sensitive magnetic resonance (MR) imaging at 4.7 T.
• Acquired multisection magnetic susceptibility-weighted echo-planar images to monitor blood deoxygenation and used dysprosium-DTPA-BMA for perfusion assessment.

Main Results:

• Observed a significant signal intensity decrease in ischemic brain, attributed to T2* decrease from increased blood deoxygenation.
• This deoxygenation correlated with decreased apparent diffusion coefficient in ischemic tissue.
• Perfusion analysis revealed a total perfusion deficit in ischemic areas and unchanged perfusion in normal brain tissue post-stroke.

Conclusions:

• Advanced MR imaging effectively monitors blood deoxygenation and perfusion deficits in ischemic stroke.
• The findings provide insights into the pathophysiology of stroke and the impact of thrombolytic therapy.
• This approach aids in the characterization of stroke progression and therapeutic response.