Rotating radial injection pattern for highly sensitive electrical impedance tomography of human lung anomalies.

Objective: Electrical Impedance Tomography (EIT) is a non-invasive technique used for lung imaging. A significant challenge in EIT is reconstructing images of deeper thoracic regions due to the low sensitivity of boundary voltages to internal conductivity variations. The current injection pattern is decisive as it influences the current path, boundary voltages, and their sensitivity to tissue changes. Approach. This study introduces a novel current injection pattern with radially placed electrodes excited in a rotating radial pattern. The effectiveness of the proposed pattern was investigated using a 3D computational model that mimics the human thorax, replicating its geometry and tissue electrical properties. To examine the detection of lung anomalies, models representing both healthy and unhealthy states, including cancer-like anomalies in three different positions, were developed. The new pattern was compared to common patterns-Adjacent, Skip 1, and Opposite-using Finite Element Analysis (FEA). The comparison focused on the current density within lung nodules and the sensitivity to changes in anomaly positions. Main Results. Results showed that the new pattern achieved the maximum current density within anomalies compared to surrounding tissues, with peak values near the closest electrode pairs to the anomalies. Specifically, current density magnitudes reached 72.73 10^{-9} A.m, 145.24 10^{-9} A.m, and 26.43 10^{-9} A.m for the three different positions, respectively. Furthermore, the novel pattern's sensitivity to anomaly position changes surpassed the common patterns.

Significance: These results demonstrate the efficiency of the proposed injection pattern in detecting lung anomalies compared to the common injection patterns.