An Investigation Into Electromagnetic Based Impedance Tomography Using Realistic Human Head Model

Abstract

College of Electrical and Mechanical Engineering, National University of Sciences and Technology, Islamabad, Pakistan Email: awaismunawar.phd06@rcms.nust.edu.pkThe objective of this research is to investigate the feasibility of Electromagnetic based Impedance Tomography (EMIT) for brain stroke detection, localization and classification. Electromagnetic based Impedance Tomography employing microwave imaging technique is an emerging brain stroke diagnostic modality. It relies on the significant contrast between dielectric properties of the normal and abnormal brain tissues. To study the interaction between micro-wave signals and head tissues, the simulations are performed using a geometrically simple 3-D ellipsoid head model with emulated stroke. Finite Element numerical technique is adopted to find the solution of Maxwell's equations to measure the transmitted and backscattered signals in forward problem. Contrast Source Inversion technique is proposed to solve the inverse scattering problem and reconstruct brain images based on calculated dielectric profiles. Detailed analysis is performed to determine the safety limits of transmitted signals to minimize ionizing effects while ensuring maximum penetration. The simulations verify the inhomogeneous and frequency-dispersive behavior of brain tissue's dielectric properties. The solution of the forward problem demonstrates the microwave signals scattering by the multilayer structure of the head model, duly validated by analytical results. The scattering phenomena can be fully capitalized by image reconstruction algorithm to obtain brain images and detect stroke presence. The initial results obtained in this research and prior work indicates that EMIT-based head imaging system has a potential for rapid stroke detection, classification, and continuous brain monitoring and offers a comparatively cost-effective solution.

Finite-element analysis of microwave scattering from a three-dimensional human head model for brain stroke detection

“…However, in this study the incorporated frequency-dependent closed-form models are evaluated at 1 GHz only. This is because 1 GHz is the most appropriate frequency for a MW head-imaging system, suggested by the previously referenced literature [ 14 , 23 , 25 , 27 , 35 , 38 , 40 , 42 ] and the evaluations we made during our research [ 43 – 45 ]. This frequency allows a good penetration of MW signals into a human head, while providing a reasonable spatial resolution of brain images.…”

“…In our earlier studies, we investigated the feasibility of EMT for brain stroke diagnostics using MW signals [ 43 ]. FEM-based frequency-domain analysis was performed using a 3D ellipsoid head model and an array of half-wave dipole antennas.…”

Levels of detail analysis of microwave scattering from human head models for brain stroke detection

“…Based on the literature discussed above, we already conducted an investigation study after careful literature survey to determine the feasibility of electromagnetic tomography (EMT) for brain stroke analysis, while making use of microwave signals ( Munawar et al, 2016b ). We performed computer simulations using a 3-D ellipsoid head model emulated with a hemorrhagic stroke.…”