Microvessel changes after post-ischemic benign and malignant hyperemia: experimental study in rats

Area of Science:

• Neuroimaging
• Vascular Biology
• Ischemic Stroke Research

Background:

• Dynamic contrast-enhanced perfusion MRI (DCE pMRI) is explored for characterizing hyperemia.
• The study investigates microvessel changes and DCE pMRI's ability to predict hyperemia type (benign vs. malignant).

Purpose of the Study:

• To elucidate the utility of DCE pMRI in characterizing post-ischemic hyperemia.
• To examine the correlation between DCE pMRI metrics and microvascular integrity.
• To determine if DCE pMRI can predict benign versus malignant hyperemia.

Main Methods:

• Middle cerebral artery occlusion (MCAO) was induced in Sprague-Dawley rats.
• Rats were assigned to groups based on occlusion duration (0.5, 3, or 6 hours) and treatment (saline or urokinase).
• Quantitative MRI analysis (rCBV, rMSI) and microscopy (LSCM, TEM) were performed for correlative studies.

Main Results:

• Benign hyperemia observed in the 0.5-hour occlusion group (saline), malignant hyperemia in the 3-hour occlusion group (urokinase).
• Malignant hyperemia showed higher rCBV (not significant) and significantly lower rMSI compared to benign hyperemia.
• Malignant hyperemia correlated with FITC-dextran extravasation, glial swelling, and vasodilation; benign hyperemia showed minimal changes.

Conclusions:

• DCE pMRI is a valuable tool for characterizing post-ischemic hyperemia.
• DCE pMRI findings correlate well with observed microvascular damage and BBB disruption.
• The study demonstrates DCE pMRI's potential in differentiating hyperemia types post-ischemia.