Imaging effective oxygen diffusivity in the human brain with multiparametric magnetic resonance imaging

Area of Science:

• Neuroimaging
• Cerebrovascular Physiology
• Biomarker Discovery

Background:

• Cerebrovascular diseases impact blood flow and oxygen delivery to the brain.
• Effective oxygen diffusivity (EOD) is a critical biomarker for microvascular function, relevant for clinical diagnosis and understanding oxygen transport.
• Existing models link EOD to oxygen extraction fraction (OEF) and cerebral blood flow (CBF).

Purpose of the Study:

• To validate existing mathematical models for EOD mapping.
• To propose and evaluate a novel, clinically applicable multiparametric MRI protocol for quantitative EOD mapping.
• To assess the feasibility of the MRI protocol by comparing its results to PET data.

Main Methods:

• Confirmed equivalence of two established oxygen transport models for EOD mapping.
• Developed a multiparametric MRI protocol using quantitative blood oxygenation level dependent (mq-BOLD) MRI for OEF and pseudo-continuous arterial spin labeling (pCASL) for CBF.
• Evaluated the protocol in 12 healthy volunteers, comparing MRI-derived EOD, OEF, and CBF with published PET data.

Main Results:

• The proposed MRI protocol generates EOD maps comparable to those from established models.
• Strong correlations were observed between MRI- and PET-derived cortical EOD, OEF, and CBF.
• Absolute values obtained via MRI and PET showed high agreement across all measured parameters.

Conclusions:

• The developed multiparametric MRI protocol is feasible for quantitative EOD mapping.
• This non-invasive MRI technique shows significant potential for the clinical assessment of patients with cerebrovascular diseases.
• The findings support the use of EOD as a valuable biomarker in neurovascular research and clinical practice.