Numerical Simulation of Inductive Phase Shift Due a Brain Hematoma

We show a theoretically electromagnetic induction method to detect the changes of fluid volume into an organic tissue. This method is technique to detect a phase shift through measurements of induced electrical currents due a RF signal. This method was designed for volumetric brain edema monitoring. Circular and planar magnetron coils were evaluated and compared for their ability to detect edema in the brain through volumetric inductive phase shift spectroscopy. The circular coil was considered as a single turn wire and the magnetron surface coil configuration was based on the principle of the cavity magnetron with successive slots. The brain cavity was modeled as an idealized sphere transversely centered with respect to the coils. The volumetric sensitivity to changes in the brain was examined by inserting in the brain cavity a spherical edema/haematoma. Spectra of inductive phase shift induced in a second circular or magnetron receiver coils were estimated between frequencies from 100 kHz to 50 MHz. Phase shift shows sensitivity to the presence of the edema/haematoma increased with frequency. The use of a planar magnetron as the receiver coil produced a substantial increase in sensitivity, in particular at higher frequency of 50 MHz.