Quantification of regional CMRO₂ in human brain using dynamic ¹⁷O-MRI at 3T

Area of Science:

• Neuroimaging
• Physiology
• Medical Physics

Background:

• Cerebral metabolic rate of oxygen consumption (CMRO2) is a critical indicator of brain tissue health.
• Current methods for CMRO2 measurement often provide only global brain metabolism data.
• Regional CMRO2 quantification is needed for detailed insights into localized brain function and metabolism.

Purpose of the Study:

• To assess the feasibility of measuring regional CMRO2 using 3 Tesla (3T) MRI.
• To investigate regional variations in CMRO2 within gray matter (GM) and white matter (WM) in healthy volunteers.
• To compare 3T MRI-derived CMRO2 values with existing literature data.

Main Methods:

• Utilized dynamic 17O-MRI with inhaled 17O gas to quantify CMRO2.
• Measured regional CMRO2 in frontal, parietal, and occipital GM and WM.
• Determined CMRO2 in deep brain structures (thalamus, striatum, insula) and cerebellum.

Main Results:

• Cortical GM CMRO2 values aligned with literature; WM values were 32-48% higher.
• Occipital GM showed significantly higher CMRO2 than frontal and parietal GM.
• Deep brain structures had lower CMRO2; cerebellum displayed good hemispheric symmetry.

Conclusions:

• Dynamic 17O-MRI is a feasible method for non-invasively determining regional CMRO2 at 3T.
• The study demonstrates the capability to differentiate regional metabolic activity within the brain.
• Findings support the use of 3T 17O-MRI for detailed brain oxygen metabolism assessment.