Isoflurane anesthesia alters ³¹P magnetic resonance spectroscopy markers compared to awake mouse brain

Phosphorus magnetic resonance spectroscopy (³¹P MRS) enables noninvasive measurement of brain energy metabolism. Preclinical studies are typically performed under isoflurane anesthesia, which can alter neuronal activity and metabolism. To address this, we compared ³¹P MRS in awake, MR-habituated mice and under isoflurane anesthesia. We demonstrate that awake ³¹P MRS in MR-habituated mice is feasible and provides spectra of comparable quality to those acquired under anesthesia. Importantly, we show that isoflurane alters brain metabolism, reducing PCr, intracellular pH, and PME levels.