Electric Current Detection by $$ T_{2}^{*} $$ Relaxivity Change: A Feasibility Study

Precise detection of electric current flowing in a conductive liquid sample by MRI (current density imaging technique – CDI) is often challenging due to required special hardware for application of electric pulses, need for sample reorientation during the experiment or for multiple current injections, and lastly, need for special pulse programs. In this study, another, much simpler approach of current detection, which based magnetic resonance spectroscopy (MRS), is considered. It is shown first theoretically and then by experiments on a phantom, that it is possible to detect currents, by change in \( T_{2}^{*} \) NMR relaxation time, with a comparable or even lower detection threshold as with CDI. In an image voxel \( T_{2}^{*} \) relaxation time changes due to magnetic field change induced by electric currents. The sensitivity of the method is proportional to the voxel linear dimension and to \( T_{2}^{*} \) relaxation time and the signal-to-noise ratio (SNR) of the signal from the voxel. While the proposed method cannot be used for an exact current determination and is sensitive only to the current component perpendicular to the static magnetic field its main advantages are simple implementation and good sensitivity that stems from an excellent SNR of proton MRS.