Oxygen extraction fraction mapping based combining quantitative susceptibility mapping and quantitative blood...

Area of Science:

• Neuroimaging
• Biomarkers
• Brain Metabolism

Background:

• Oxygen extraction fraction (OEF) is crucial for assessing brain metabolism.
• Quantitative susceptibility mapping (QSM) combined with quantitative blood oxygen level-dependent (qBOLD) magnitude enables noninvasive OEF mapping.
• Investigating OEF mapping variations between single-delay and multi-delay arterial spin-labeling (ASL) is essential.

Purpose of the Study:

• To compare OEF mapping variations between single-delay and multi-delay ASL techniques.
• To evaluate the impact of different ASL methods on OEF measurements.
• To understand how ASL technique choice influences OEF assessment in conjunction with QSM and qBOLD.

Main Methods:

• Twenty healthy participants underwent 3.0T MRI scans.
• Acquired sequences included multi-echo spoiled gradient-echo, multi-delay ASL, and magnetization-prepared rapid gradient echo.
• OEF was calculated using single-delay ASL (1780 ms), multi-delay ASL with transit-corrected cerebral blood flow (CBF), and multi-delay ASL with arterial cerebral blood volume (CBV).

Main Results:

• Multi-delay ASL resulted in significantly lower OEF estimates compared to single-delay ASL.
• Average whole-brain OEF values were: single-delay ASL (41.5 ± 1.7%), multi-delay ASL (transit-corrected CBF) (41.3 ± 1.9%), and multi-delay ASL (arterial CBV) (40.9 ± 1.9%).
• A significant inverse correlation was observed between OEF and venous CBV under steady-state conditions using multi-delay ASL (r = 0.5834, p = 0.0069).

Conclusions:

• Arterial spin-labeling methods significantly impact OEF mapping when used with QSM and qBOLD models.
• Differences in OEF measurements due to ASL technique must be considered when applying these models, especially in disease states.
• This highlights the importance of specifying the ASL method for reproducible and comparable OEF quantification.