Comparison of Complex Open Domain Electrical Impedance Tomography Methods.

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Electrical Engineering

Background:

• Intraoperative surgical margin assessment (SMA) is critical for complete tumor removal.
• Current SMA techniques can be time-consuming or lack real-time feedback.
• Electrical Impedance Tomography (EIT) offers a non-invasive imaging modality.

Purpose of the Study:

• To evaluate complex 3D EIT for intraoperative SMA.
• To assess the performance of difference and absolute EIT methods.
• To investigate the potential of EIT for distinguishing tissue types.

Main Methods:

• Utilized a custom electrode array for multi-frequency impedance data collection (100 Hz - 1 MHz).
• Optimized electrode pressure (2-5 kPa) and employed saline calibration for accurate data.
• Introduced a novel best fit factor (β) for complex EIT reconstructions and pixel-based tissue classification.

Main Results:

• Difference EIT demonstrated high sensitivity (0.92) and specificity (0.90) for conductivity (σ) at 100 Hz with rapid 1.67-second reconstructions.
• Absolute EIT showed slightly better quantitative metrics for σ imaging (AUC=0.90, Accuracy=0.86) but with significantly longer processing times (150.6 seconds).
• Simulations indicated sufficient contrast for permittivity (ε) in tissue classification, though experimental ε reconstructions were less performant.

Conclusions:

• Difference EIT is the most promising method for real-time intraoperative SMA due to its speed and accuracy.
• Absolute EIT, while accurate, is less feasible for real-time applications.
• This study advances the potential for real-time intraoperative SMA using a novel complex EIT reconstruction method.