MRI-based oxygen extraction fraction mapping using qBOLD, QSM, and hybrid QSM-qBOLD methods: Methodological advances,...

Area of Science:

• Neuroimaging
• Physiology
• Medical Physics

Background:

• Oxygen extraction fraction (OEF) quantifies cerebral oxygen utilization, complementing perfusion and BOLD MRI.
• Positron Emission Tomography (PET) is the gold standard for OEF and CMRO₂ but faces accessibility and operational challenges.
• MRI-based methods are being developed to overcome PET limitations for OEF assessment.

Purpose of the Study:

• To review and discuss various MRI-derived oxygen extraction fraction (OEF) mapping techniques.
• To highlight the advancements and challenges in MRI-based OEF quantification.
• To explore the clinical potential of MRI-derived OEF.

Main Methods:

• Quantitative BOLD (qBOLD) methods analyze signal decay from deoxyhemoglobin.
• Quantitative Susceptibility Mapping (QSM) provides complementary susceptibility information.
• Hybrid QSM-qBOLD (QQ) methods combine magnitude and susceptibility data.
• Advanced techniques include constrained qBOLD, Bayesian reconstruction, and AI-assisted approaches.

Main Results:

• Classical qBOLD faces limitations like parameter degeneracy and noise sensitivity.
• QSM alone cannot differentiate deoxygenation from other susceptibility sources.
• Hybrid methods and recent developments aim to enhance stability, efficiency, and reduce assumptions.
• Validation against PET remains a key challenge due to limited comparative studies.

Conclusions:

• MRI-based OEF mapping shows significant potential as an alternative to PET.
• Ongoing research focuses on improving accuracy, robustness, and clinical applicability.
• Clinical applications are particularly promising for conditions involving impaired oxygen delivery, extraction, or metabolism.