Analysis of three-dimensional software EIT (electrical impedance tomography) phantoms by the finite element method

Area of Science:

• Biomedical Engineering
• Computational Electromagnetics

Background:

• Electrical impedance tomography (EIT) typically uses 2D finite element solutions for imaging.
• A key assumption is that current flow is confined to the measurement plane, neglecting out-of-plane current distribution.
• Real-world conductivity distributions are often 3D, potentially introducing errors in 2D EIT models.

Purpose of the Study:

• To investigate the impact of 3D conductivity variations on EIT measurements.
• To demonstrate the limitations of 2D assumptions in EIT imaging.
• To quantify the effects of out-of-plane conductivity on measured voltages.

Main Methods:

• A 3D finite element analysis was employed to model current flow and voltage distribution.
• Simulations were performed using conductivity distributions identical on the measurement plane but varied in the out-of-plane direction.
• Comparison of measured voltage differences between 2D and 3D models.

Main Results:

• 3D conductivity variations near the measurement plane can considerably affect measured voltage values.
• Differences in out-of-plane conductivity, even with identical in-plane conductivity, lead to distinct voltage measurements.
• The study highlights the sensitivity of EIT to 3D conductivity heterogeneity.

Conclusions:

• The assumption of negligible out-of-plane current flow in 2D EIT can lead to inaccuracies.
• Accurate EIT imaging may require incorporating 3D conductivity information, especially in heterogeneous objects.
• 3D finite element analysis is crucial for understanding and mitigating these effects in EIT.