Characterizing the diffusion/perfusion mismatch in experimental focal cerebral ischemia

Area of Science:

• Neuroscience
• Medical Imaging
• Ischemic Stroke Research

Background:

• Diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) are crucial for detecting acute ischemic stroke.
• A diffusion/perfusion mismatch, where PWI volume exceeds DWI volume, is common early after stroke onset.

Purpose of the Study:

• To investigate the temporal evolution of the diffusion/perfusion mismatch in rat models of permanent and transient focal cerebral ischemia.
• To compare lesion development and final infarct volume between permanent and temporary middle cerebral artery occlusion (MCAO).

Main Methods:

• Utilized intraluminal middle cerebral artery occlusion (MCAO) in Sprague-Dawley rats to create permanent and 60-minute temporary ischemia models.
• Performed DWI and arterial spin-labeled PWI at multiple time points (30-180 minutes post-occlusion).
• Calculated lesion volumes and determined 24-hour infarct volume using triphenyltetrazolium chloride staining.

Main Results:

• In permanent MCAO, the diffusion lesion (ADC map) was smaller than the perfusion lesion (cerebral blood flow map) up to 60 minutes, but this difference diminished after 90 minutes.
• In transient MCAO, the initial diffusion/perfusion mismatch was similar, but lesion volumes on both DWI and PWI maps significantly decreased after reperfusion.
• A significant difference in 24-hour infarct volumes was observed between the permanent and temporary occlusion groups.

Conclusions:

• The diffusion/perfusion mismatch dynamics differ between permanent and transient focal cerebral ischemia.
• Reperfusion significantly reduces lesion volumes in temporary ischemia models, highlighting the potential for therapeutic intervention.
• These findings contribute to understanding stroke pathophysiology and imaging biomarkers.