Handling white-matter anisotropy in BEM for the EEG forward problem

Emmanuel Olivi (1) , Théodore Papadopoulo (1) , Maureen Clerc (1)

1 ATHENA - Computational Imaging of the Central Nervous System

Conductivity of tissues in the vicinity of the sources is especially influential on the MEG and EEG forward fields. Those tissues include white matter, whose conductivity is anisotropic because of its fiber structure. While white matter anisotropy can be measured thanks to Diffusion-Weighted MRI, it is rarely incorporated in MEG and EEG head models. Boundary Element Methods can only deal with piecewise constant conductivities, therefore ruling out white matter anisotropy that has a complex structure, and Finite Element Method have been developed to deal with anisotropic conductivity, but require very fine meshes, thus huge linear systems. The purpose of this paper is to extend the BEM framework to incorporate white matter anisotropy by treating anisotropic conductivity as a perturbation of an isotropic one.

Résoudre un problème inverse de localisation en EEG, requiert une bonne modélisation de la tête du patient, ainsi que des conductivités des différents milieux traversés. Ceux proches des sources ont particulièrement de l'influence. L'anisotropie de la matière blanche peut être estimée par l'IRM de diffusion, et à partir de ce tenseur de diffusion, il est possible d'estimer le tenseur de conductivité électrique. Ce travail propose une méthode pour prendre en compte une anisotropie locale dans la BEM (Boundary Element Method).

Mots clés: White-matter; Conductivity tensor; MEEG; BEM; EEG

Domaines: Imagerie médicale

Emmanuel Olivi, Théodore Papadopoulo, Maureen Clerc. Handling white-matter anisotropy in BEM for the EEG forward problem. ISBI 2011 - 8th IEEE International Symposium on Biomedical Imaging: From Nano to Macro, Mar 2011, Chicago, United States. pp.799 - 802, ⟨10.1109/ISBI.2011.5872526⟩. ⟨inria-00578876v2⟩