Functional conductivity imaging: quantitative mapping of brain activity

Motivation: Theory and modelling suggest that detection of neuronal activity may be feasible using phase sensitive MRI methods. Goal(s): To demonstrate successful application of phase-based MREPT to functional tasks in brainApproach: Using bFFE optimised for fast acquisition, data were acquired from 5 participants undertaking visual stimulation or somatosensory stimulation. Electrical conductivity values extracted from phase images were fitted with the measured stimulus response function. Results: Images showed consistent activation of visual circuitry (~0.1 S/m) in both grey and white matter with similar circuit responses to somatosensory stimulation. Conductivity increased with stimulus duration or increased contrast and was faster, temporally, than BOLD. Impact: Functional conductivity imaging (funCI) reveals activity in both grey and white matter. The sensitivity, repeatability and time course of funCI shows that MRI can detect brain activation beyond changes in blood supply.