MR-Encephalography: Fast multi-channel monitoring of brain physiology with magnetic resonance.

A new approach to measure activation-related changes in the brain by magnetic resonance is described offering high temporal resolution of 10-100 measurements per second. This is achieved by simultaneous multi-channel reception where the spatial resolution during continuous observation is determined by the sensitive volume of each coil alone without any additional spatial encoding gradients. Experimental results demonstrate the very high sensitivity of this approach, which allows to directly measure and monitor the stimulus-dependent hemodynamic response as well as ECG- and breathing-related signal fluctuations. One-dimensional spatial encoding either parallel or orthogonal to the cortex demonstrates that vascular signals can be identified by the pronounced signal variation at the ECG-frequency. Noise analysis at different frequencies reveals regional signal fluctuations in the frequency range between 2 and 10 Hz. Furthermore, initial results show that frequency changes in the order of <0.03 Hz corresponding to <1 nano Tesla can be detected. In addition to its potential use in neuroscientific studies, this new method opens a wide range of applications for fast physiological monitoring and can be easily combined with conventional high-resolution imaging.