Reproducibility of CMRO₂ determination using dynamic ¹⁷ O MRI

Area of Science:

• Neuroimaging
• Biophysics
• Medical Physics

Background:

• Cerebral metabolic rate of oxygen consumption (CMRO2) is a critical indicator of brain function.
• Accurate and reproducible measurement of CMRO2 is essential for understanding neurological disorders.
• 17O MRI offers a promising non-invasive method for quantifying CMRO2.

Purpose of the Study:

• To evaluate the reproducibility of 17O MRI for determining CMRO2 in healthy individuals.
• To investigate the impact of image acquisition and reconstruction parameters on CMRO2 quantification.
• To assess the influence of temporal resolution and partial volume correction on CMRO2 measurements.

Main Methods:

• Simulated 17O MRI data were used to analyze the effects of temporal resolution (Δt) and partial volume correction (PVC).
• In vivo 17O MRI was performed on three healthy volunteers across two separate sessions.
• Measurements utilized a density-adapted radial sequence with a golden angle acquisition scheme and 70% enriched 17O gas administration via rebreathing.
• Data were processed with a PVC algorithm, and CMRO2 was calculated for gray matter (GM) and white matter (WM) using a three-phase metabolic model.

Main Results:

• Simulations indicated that PVC application and a temporal resolution of Δt ≤ 2:00 min improved CMRO2 determination accuracy.
• In vivo measurements yielded CMRO2 values of 2.31 ± 0.1 μmol/g/min in GM and 0.69 ± 0.04 μmol/g/min in WM.
• Intra-volunteer and inter-volunteer coefficients of variation (CoV) for CMRO2 were 0.3-5.5% and 4.3-5.0%, respectively, demonstrating good reproducibility.

Conclusions:

• The developed experimental setup for 17O MRI enables reproducible in vivo determination of CMRO2 in healthy volunteers.
• Optimizing parameters such as partial volume correction and temporal resolution enhances the accuracy of CMRO2 quantification.
• This study validates 17O MRI as a reliable tool for assessing brain oxygen metabolism.