Use of the reciprocal problems in electro-magnetic source imaging of the human brain

Date

2003-09-21

Author

Gençer, Nevzat Güneri

Metadata

Show full item record

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Item Usage Stats

168
views

0
downloads

In this work, solution of the Electro-magnetic source imaging forward problem is formulated using the reciprocity theorem. Lead field solutions for electrode potentials and sensor magnetic fields are computed for a realistic head model using the Finite Element Method. Potentials and magnetic fields obtained using the lead fields are compared to analytical solutions and direct numerical solutions. It is found that the accuracy of lead field based solution is comparable to the accuracy of direct numerical solutions. Compared to the analytical solutions, the error for numerical methods is below 1% inside the volume. The error increases up to 3% near the boundary. Once the matrices defining the lead field are formed, it is possible to obtain very fast forward problem solutions. For a linear realistic head mesh with 450000 nodes, directly obtaining a forward problem solution for a single dipole takes about 110 seconds on an 8 processor parallel computer. Using the same computing platform, it takes 11 hours to form the lead field matrix for 256 sensors. Once the matrix is formed, individual solutions can be obtained in under 1 second using a single processor.

Subject Keywords

Reciprocity theorem, Lead field, Finite element method, Electro, Magnetic source imaging, Forward problem

URI

https://hdl.handle.net/11511/35305

DOI

https://doi.org/10.1109/iembs.2003.1280465

Collections

Department of Electrical and Electronics Engineering, Conference / Seminar

Suggestions

OpenMETU
Core

Investigation of nonplanar perfectly matched absorbers for finite-element mesh truncation Kuzuoğlu, Mustafa (1997-03-01) In this paper, we present a detailed theoretical and numerical investigation of the perfectly matched layer (PML) concept as applied to the problem of mesh truncation in the finite-element method (FEM), We show that it is possible to extend the Cartesian PML concepts involving half-spaces to cylindrical and spherical geometries appropriate for closed boundaries in two and three dimensions by defining lossy anisotropic layers in the relevant coordinate systems, By using the method of separation of variables,...
Propagation of ionizing short laser pulses in a nonlinear optical medium Deveci, Atalay; Yedierler, Burak; Department of Physics (2021-2-15) Using a pseudo-spectral method that is split step Fourier method, obtaining a solutionfor propagation of ionizing short Gaussian pulse would be computationally inexpen-sive and practical. For a solution obtained by using split step Fourier method, themost important parameter to choose is step size. However, using either large or smallstep size may yield different numerical errors in the final result. For a large step size,general evolution of the Gaussian pulse could be predicted well but small changesmigh...
Evaluation of Hypersingular Integrals on Non-planar Surfaces Selcuk, Gokhun; Koç, Seyit Sencer (2014-05-16) Solving electric field integral equation (EFIE) with Nystrom method requires accurate evaluation of hypersingular surface integrals since this method does not use divergence conforming basis and testing functions. The success of the method also depends on accurate representation of non-planar characteristics of the scattering object. In this study Hadamard finite part interpretation is used to evaluate hypersingular integrals over non-planar surfaces, which are represented by their Taylor series expansions....
Recursive Two-Way Parabolic Equation Approach for Modeling Terrain Effects in Tropospheric Propagation Ozgun, Ozlem (2009-09-01) The Fourier split-step method is a one-way marching-type algorithm to efficiently solve the parabolic equation for modeling electromagnetic propagation in troposphere. The main drawback of this method is that it characterizes only forward-propagating waves, and neglects backward-propagating waves, which become important especially in the presence of irregular surfaces. Although ground reflecting boundaries are inherently incorporated into the split-step algorithm, irregular surfaces (such as sharp edges) in...
Multiscale Modeling of Thin-Wire Coupling Problems Using Hybridization of Finite Element and Dipole Moment Methods and GPU Acceleration ÖZGÜN, ÖZLEM; Mittra, Raj; Kuzuoğlu, Mustafa (2020-01-01) In this article, a hybrid numerical method, called finite element method (FEM) + dipole moment (DM), is presented for efficient solution of multiscale electromagnetic radiation and scattering problems that involve structures with fine features, such as thin-wire antennas or objects. In this method, the FEM is hybridized with the DM approach to help ease certain computational burdens, such as mesh refinement, ill-conditioning, memory overload, and long computation times, when solving multiscale problems with...

Citation Formats

N. G. Gençer, “Use of the reciprocal problems in electro-magnetic source imaging of the human brain,” 2003, vol. 25, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/35305.