Abstract #0050

The potential for gas-free measurements of absolute oxygen metabolism during both baseline and activation states in the human brain

Eulanca Y. Liu^1,2, Jia Guo³, Aaron B. Simon⁴, Frank Haist⁵, David J. Dubowitz^2,6, and Richard B. Buxton^2,6

¹Neurosciences Graduate Program, Medical Scientist Training Program, University of California, San Diego, La Jolla, CA, United States, ²Center for Functional MRI, University of California, San Diego, La Jolla, CA, United States, ³Radiology, Stanford University, Stanford, CA, United States, ⁴Radiation Medicine and Applied Sciences, University of California, San Diego, La Jolla, CA, United States, ⁵Psychiatry, Center for Human Development, University of California, San Diego, La Jolla, CA, United States, ⁶Radiology, University of California, San Diego, La Jolla, CA, United States

We tested noninvasive methods to measure absolute oxygen metabolism (CMRO₂) in both baseline and activation states without the use of special gases: VSEAN to measure baseline O₂ extraction fraction (OEF), and FLAIR-GESSE to measure R₂’ to estimate the scaling parameter M. Primary findings were: M derived from R₂’ had less variation across subjects compared to hypercapnia-derived M; OEF values were in good agreement with previous PET findings; and, variation of baseline CBF/CMRO₂ coupling across subjects does not follow activation coupling, suggesting different mechanisms may be involved. These results support the potential of gas-free methods for quantitative physiological measurements.

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