High-speed whole-brain oximetry by golden-angle radial MRI

Area of Science:

• Neuroimaging
• Magnetic Resonance Imaging (MRI)
• Cerebral Metabolism

Background:

• Accurate measurement of whole-brain cerebral metabolic rate of oxygen (CMRO2) is crucial for understanding brain function and disease.
• Existing MRI techniques may have limitations in speed or flexibility for simultaneously quantifying key neurometabolic-vascular parameters.
• The OxFlow technique offers a method for simultaneous quantification of venous oxygen saturation (SvO2) and total cerebral blood flow (tCBF).

Purpose of the Study:

• To develop and validate an improved, radial encoding-based imaging approach, termed radial OxFlow (rOxFlow), for quantifying CMRO2.
• To simultaneously measure draining vein SvO2 and tCBF using the novel rOxFlow sequence.
• To compare the performance of rOxFlow against the established Cartesian OxFlow (cOxFlow) sequence.

Main Methods:

• Ten healthy subjects underwent MRI using both rOxFlow and cOxFlow sequences during a repeated breath-hold paradigm.
• CMRO2 was calculated at baseline using acquired data and an assumed arterial O2 saturation of 97%.
• Breath-hold-induced changes in SvO2 and tCBF were quantified for both sequences.

Main Results:

• No significant differences were observed in baseline or peak SvO2 and tCBF values between rOxFlow and cOxFlow.
• Baseline CMRO2 values showed good agreement between the two methods (cOxFlow: 111.5 ± 26.8; rOxFlow: 120.1 ± 19.6 µmol O2/min/100g).
• Statistical analysis confirmed P > 0.05 for all measured parameters between sequences, indicating comparable accuracy.

Conclusions:

• The radial OxFlow (rOxFlow) technique demonstrates good agreement with the Cartesian OxFlow (cOxFlow) method for measuring neurometabolic-vascular parameters.
• rOxFlow offers superior temporal resolution and greater reconstruction flexibility while maintaining high signal-to-noise ratio (SNR).
• This improved imaging approach holds promise for advanced research in brain metabolism and hemodynamics.