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Comparison of applied and induced current electrical impedance tomography
Louis-François Tanguay1, Hervé Gagnon, Robert Guardo
1Institut de génie biomédical, Ecole Polytechnique de Montréal, Montréal, QC H3C 3A7, Canada.
IEEE Transactions on Bio-Medical Engineering
|September 18, 2007
Summary
Induced current electrical impedance tomography (IC-EIT) shows lower spatial resolution and central bias compared to applied current EIT (AC-EIT). This study provides a system for direct comparison under identical conditions.
Area of Science:
- Biomedical Engineering
- Medical Imaging
- Electrical Engineering
Background:
- Conventional applied current electrical impedance tomography (AC-EIT) has limitations.
- Induced current electrical impedance tomography (IC-EIT) is proposed as a potential improvement.
- Direct experimental comparisons under identical conditions are lacking.
Purpose of the Study:
- To develop and evaluate a system capable of rapidly switching between AC-EIT and IC-EIT.
- To provide a direct, experimental comparison of IC-EIT and AC-EIT performance.
- To assess the imaging capabilities of IC-EIT versus AC-EIT.
Main Methods:
- A novel system was designed to switch between AC-EIT and IC-EIT modes.
- Objects were imaged in a saline tank under identical conditions for both modes.
- Data acquisition involved 8 coils and 16 electrodes, yielding 120 (IC-EIT) and 104 (AC-EIT) measurements.
- Difference images were reconstructed using the maximum a posteriori method.
Main Results:
- Spatial resolution was found to be lower in IC-EIT images compared to AC-EIT images.
- The radial direction showed a more pronounced decrease in spatial resolution for IC-EIT.
- IC-EIT demonstrated a bias towards the center when positioning conductivity perturbations.
- These findings are specific to the tested coil configuration.
Conclusions:
- The developed system enables stable, comparative evaluation of EIT imaging modes.
- IC-EIT, in its current configuration, does not surpass AC-EIT in terms of spatial resolution and positioning accuracy.
- The system is a valuable tool for validating novel coil configurations for EIT.
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