Influence of bad contact electrode on electrical impedance tomography data quality: a perspective of clinical application

Abstract This study aimed to evaluate the effect of bad contact electrodes on the quality of electrical impedance tomography (EIT) data and the reliability of lung ventilation imaging. Thirty healthy volunteers were examined using EIT under normal relaxed tidal breathing in a supine position. The five electrode–skin contact conditions (C1–C5) for electrode No. 2 were defined by systematically varying the contact area. Specifically, C1 represented full contact, C2 covered 25% of the electrode surface, C3 covered 50%, C4 covered 75%, and C5 involved completely covering the electrode with an insulating material to simulate high impedance. Three scenarios (S A , S B , S C ) were established: S A maintained impedance stability, S B simulated variations in contact, and S C introduced dynamic changes in impedance during a single breath cycle. EIT parameter-based deviation scores were used to assess spatial and temporal ventilation distributions across varying electrode contact conditions and the Bland–Altman plot was used to assess image quality. Deviation scores in S A consistently hovered around 0.0, except for C5, which scored 8.5 ± 4.0. In contrast, S B displayed significantly higher deviation scores, with C2 recording the lowest at 4.0 ± 4.0. The absolute differences in tidal impedance variation between S A and S B remained minimal across all conditions. However, significant differences emerged between S A and S C from C2 onwards, where a notable shift in left–right lung ventilation distribution was observed. Changes in electrode contact impedance significantly impact the quality of EIT data. While absolute impedance within a stable range has minimal effect, fluctuations within a breath cycle compromise image quality.