Validation of a 3D reconstruction algorithm for EIT of human brain function in a realistic head-shaped tank

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Electrical Engineering

Background:

• Electrical impedance tomography (EIT) shows promise for imaging human brain activity.
• Current EIT reconstruction algorithms often model the head as a homogeneous sphere.
• This simplification leads to significant localization errors in imaging brain activity.

Purpose of the Study:

• To investigate the impact of head shape and skull presence on EIT reconstruction accuracy.
• To quantify localization errors when using a homogeneous sphere model for EIT data from realistic head models.
• To assess the contribution of the skull to localization errors in EIT.

Main Methods:

• A 3D EIT reconstruction algorithm based on a homogeneous sphere model was simulated.
• Experiments were conducted in saline-filled tanks (hemispherical and head-shaped) with and without a human skull.
• A sponge with known resistivity contrast was used to simulate an impedance change.

Main Results:

• Localization errors were quantified in different tank geometries and with/without a skull.
• Using a head-shaped tank increased localization errors compared to a hemispherical tank.
• The presence of a human skull significantly increased localization errors (10.3-18.7%) compared to a skull-less head model (3.1-13.3%).

Conclusions:

• A homogeneous sphere model in EIT reconstruction algorithms introduces significant localization errors, particularly due to the skull.
• The skull's presence shifts the apparent location of impedance changes towards the image center.
• Employing realistic head models in EIT reconstruction is crucial for improving human brain imaging accuracy.