First implementation of dynamic oxygen-17 ( 17 O) magnetic resonance imaging at 7 Tesla during neuronal stimulation in the human brain

Objective First implementation of dynamic oxygen-17 ( 17 O) MRI at 7 Tesla (T) during neuronal stimulation in the human brain. Methods Five healthy volunteers underwent a three-phase 17 O gas ( 17 O 2 ) inhalation experiment. Combined right-side visual stimulus and right-hand finger tapping were used to achieve neuronal stimulation in the left cerebral hemisphere. Data analysis included the evaluation of the relative partial volume (PV)-corrected time evolution of absolute 17 O water (H 2 17 O) concentration and of the relative signal evolution without PV correction. Statistical analysis was performed using a one-tailed paired t test. Blood oxygen level-dependent (BOLD) experiments were performed to validate the stimulation paradigm. Results The BOLD maps showed significant activity in the stimulated left visual and sensorimotor cortex compared to the non-stimulated right side. PV correction of 17 O MR data resulted in high signal fluctuations with a noise level of 10% due to small regions of interest (ROI), impeding further quantitative analysis. Statistical evaluation of the relative H 2 17 O signal with PV correction ( p = 0.168) and without ( p = 0.382) did not show significant difference between the stimulated left and non-stimulated right sensorimotor ROI. Discussion The change of cerebral oxygen metabolism induced by sensorimotor and visual stimulation is not large enough to be reliably detected with the current setup and methodology of dynamic 17 O MRI at 7 T.