Ischemic thresholds for gray and white matter: a diffusion and perfusion magnetic resonance study

Area of Science:

• Neuroscience
• Radiology
• Stroke Research

Background:

• Animal models suggest differing neurochemical responses to ischemia between gray matter (GM) and white matter (WM).
• It remains unclear if these differences translate to distinct infarction thresholds in human ischemic stroke.

Purpose of the Study:

• To investigate whether gray matter (GM) and white matter (WM) exhibit different infarction thresholds in patients with acute ischemic stroke.
• To utilize magnetic resonance (MR) techniques to assess tissue-specific diffusion and perfusion parameters.

Main Methods:

• Magnetic resonance (MR) imaging was conducted on patients within 24 hours of acute hemispheric ischemic stroke.
• Calculated parameters included cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), and apparent diffusion coefficient (ADC).
• Tissue-specific infarction thresholds were determined for GM and WM using probabilistic segmentation.

Main Results:

• Infarction thresholds for CBF were significantly higher in GM compared to WM (P<0.0001).
• GM also demonstrated significantly higher thresholds for CBV (P<0.0001) and ADC (P<0.001) than WM.
• A trend towards shorter MTT was observed in GM compared to WM (P=0.11).

Conclusions:

• Gray matter (GM) exhibits a higher infarction threshold for CBF, CBV, and ADC than white matter (WM) in acute ischemic stroke.
• Tissue-specific thresholds, rather than whole-brain values, offer a more precise method for predicting infarction likelihood in stroke patients.
• This finding has implications for assessing patient eligibility for potential stroke therapies.