Optimized electrode positions and stimulation patterns in head EIT

Electrical Impedance Tomography (EIT) has potential for imaging of the head to image cerebral edema and stroke, and to assist the EEG inverse problem. One key challenge is the low distinguishability of head EIT. In this paper, we develop a strategy to improve distinguishability by optimizing electrode configurations and stimulation and measurement patterns. In a hemispherical simulation phantom, electrode positions and patterns were evaluated for (i) 1-ring 16 electrodes, (ii) 2-ring equal number of electrodes, (iii) 3-ring electrode geometries and (iv) 10-20 system of EEG electrode configuration. A selected best case was experimentally evaluated using a KHU Mark2 EIT system and compatible saline phantom. The objective was to design an EIT electrode geometry and stimulation pattern to yield high SNR across a large region of interest within the head. Results show that multi-level electrode geometries produced higher distinguishability, especially the multi-layer 10-20 electrode configuration provides the highest distinguishability and best image reconstruction performance.