Brain oxygen extraction fraction mapping in patients with multiple sclerosis

Area of Science:

• Neuroimaging
• Medical Physics
• Neurology

Background:

• Multiple Sclerosis (MS) is a demyelinating disease affecting the central nervous system.
• Assessing tissue oxygenation is crucial for understanding MS pathophysiology.
• Current methods for measuring brain oxygen extraction fraction (OEF) may have limitations.

Purpose of the Study:

• To demonstrate the feasibility of whole brain OEF mapping in multiple sclerosis (MS) patients.
• To quantify lesion-specific and regional OEF abnormalities in MS.
• To evaluate OEF as a potential quantitative marker for tissue oxygen utilization in MS.

Main Methods:

• Magnetic Resonance Imaging (MRI) using multi-echo gradient echo sequences was employed.
• OEF and neural tissue susceptibility (χ) maps were computed for 22 MS patients and 11 healthy controls (HC).
• Linear mixed-effect models and linear regression were used for statistical analysis of OEF and χ values in lesions and whole brain regions.

Main Results:

• Chronic active MS lesions exhibited a hyperintense rim with higher OEF and χ compared to the lesion core.
• MS patients showed significantly lower whole-brain OEF and higher χ compared to HC.
• OEF contrast in the rim and core of lesions differed significantly from normal-appearing white matter.

Conclusions:

• Whole brain OEF mapping is a feasible quantitative MRI technique for MS research.
• OEF abnormalities are detectable both within MS lesions and in the broader brain tissue.
• OEF mapping holds promise as a valuable biomarker for assessing tissue oxygen metabolism in multiple sclerosis.