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

Abstract

In this paper, we have presented a microwave scattering analysis from multiple human head models. This study incorporates different levels of detail in the human head models and its effect on microwave scattering phenomenon. Two levels of detail are taken into account; (i) Simplified ellipse shaped head model (ii) Anatomically realistic head model, implemented using 2-D geometry. In addition, heterogenic and frequency-dispersive behavior of the brain tissues has also been incorporated in our head models. It is identified during this study that the microwave scattering phenomenon changes significantly once the complexity of head model is increased by incorporating more details using magnetic resonance imaging database. It is also found out that the microwave scattering results match in both types of head model (i.e., geometrically simple and anatomically realistic), once the measurements are made in the structurally simplified regions. However, the results diverge considerably in the complex areas of brain due to the arbitrary shape interface of tissue layers in the anatomically realistic head model.After incorporating various levels of detail, the solution of subject microwave scattering problem and the measurement of transmitted and backscattered signals were obtained using finite element method. Mesh convergence analysis was also performed to achieve error free results with a minimum number of mesh elements and a lesser degree of freedom in the fast computational time. The results were promising and the E-Field values converged for both simple and complex geometrical models. However, the E-Field difference between both types of head model at the same reference point differentiated a lot in terms of magnitude. At complex location, a high difference value of 0.04236 V/m was measured compared to the simple location, where it turned out to be 0.00197 V/m. This study also contributes to provide a comparison analysis between the direct and iterative solvers so as to find out the solution of subject microwave scattering problem in a minimum computational time along with memory resources requirement.It is seen from this study that the microwave imaging may effectively be utilized for the detection, localization and differentiation of different types of brain stroke. The simulation results verified that the microwave imaging can be efficiently exploited to study the significant contrast between electric field values of the normal and abnormal brain tissues for the investigation of brain anomalies. In the end, a specific absorption rate analysis was carried out to compare the ionizing effects of microwave signals to different types of head model using a factor of safety for brain tissues. It is also suggested after careful study of various inversion methods in practice for microwave head imaging, that the contrast source inversion method may be more suitable and computationally efficient for such problems.

Simulation and Analysis of Variable Antenna Designs for Effective Stroke Detection

“…The induced electric field values (emw) were 0.16, 0.1, 0.12, 0.25, and 0.13 for when the antenna-A, antenna-B, antenna-C, antenna-D, and antenna-E respectively are used for the stroke monitoring. The higher induced field implies that the details of the anatomical significance can be captured rapidly and with finer details, with measurement possible for minutely detailed examinations [42]. Hence, from this result, it comes out that the antenna-D should be the most desirable choice.…”

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.…”

“…We also conducted a level of details analysis of MW scattering from different complexity head models. The aim was to highlight the significance of incorporating realistic details into head models during computer simulations for brain stroke analysis [ 45 ].…”

Brain Stroke Detection Based on Microwave Imaging

“…두부 모델을 보다 실제 환경에 적합한 모델로 만들기 위하여 Qureshi 등은 Zubal이 제시한 타원형 두부 모델보 다 훨씬 실제환경에서 MRI로 측정한 데이터를 사용하여 보다 발전된 모델을 구축한 후, 각 모델을 적용하여 FEM 방식에 기반한 마이크로파 단층기법(tomography)으로 뇌 졸중 진단 모사를 수행하였다 [16] .…”