Patient-specific solution of the electrocorticography forward problem in deforming brain

Area of Science:

• Neurosurgery
• Biomedical Engineering
• Computational Neuroscience

Background:

• Invasive intracranial electroencephalography (iEEG), or electrocorticography (ECoG), is vital for epilepsy surgery planning.
• Accurate modeling of brain geometry and conductivity is essential for solving the iEEG forward problem, crucial for seizure onset zone localization.
• Brain deformation caused by electrode implantation invalidates pre-operative imaging, and post-operative imaging modalities have limitations.

Purpose of the Study:

• To develop and validate a biomechanics-based image warping procedure to accurately represent post-operative brain geometry for iEEG modeling.
• To improve the accuracy of epilepsy surgery planning by accounting for brain deformation and patient-specific tissue conductivity.

Main Methods:

• Utilized preoperative MRI for tissue classification and postoperative CT for electrode localization.
• Employed a biomechanics-based image warping procedure for non-rigid registration of pre-operative to post-operative brain configurations.
• Solved the iEEG forward problem using the finite element method (FEM) on the predicted deformed geometry, incorporating patient-specific conductivity.

Main Results:

• Demonstrated significant differences in predicted electric potentials and lead field matrices between models with original and deformed brain geometries.
• The biomechanics-based warping accurately predicted the deformed post-operative brain geometry.
• The finite element method effectively accounted for patient-specific tissue inhomogeneity and anisotropy.

Conclusions:

• A biomechanics-based image warping procedure enables accurate modeling of deformed brain geometry after iEEG electrode implantation.
• This approach significantly impacts the accuracy of the iEEG forward problem solution, crucial for epilepsy surgery planning.
• Rapid and accurate forward problem solutions in deformed brains are achievable, enhancing surgical planning for epilepsy patients.