Functional 17 O-MRI of cerebral oxygen consumption in the activated rat brain

Assessing CMRO 2 during neuronal activation is essential to understanding brain energy metabolism and neurovascular coupling. Over the past decades, preclinical studies have yielded variable results, likely due to differences in techniques, models, and stimulation paradigms. Here, we present the first study using 17 O-MRI to directly quantify CMRO 2 during paw electrical stimulation in rats at 11.7 T. CMRO 2 was significantly higher in the activated cortex (3.28 ± 0.27 µmol/g/min) than in the control cortex (2.89 ± 0.32 µmol/g/min), corresponding to a 13.8% ± 7.9% increase. A strong negative correlation was found between ΔCMRO 2 and resting CMRO 2 , suggesting that baseline oxidative metabolism influences the evoked response. Flow-related parameters ( K G , K L , k W ) and cerebral blood flow (CBF) were also estimated, revealing a significant 22% increase in CBF in the activated cortex. These findings demonstrate that 17 O-MRI is a robust, noninvasive tool for direct CMRO 2 quantification during functional activation, with strong potential as a new standard for studying oxidative brain metabolism.