Sodium concentration imaging in dermis layer by square-wave open electrical impedance tomography (SW-oEIT) with...

Area of Science:

• Biomedical Engineering
• Electrical Impedance Tomography
• Medical Imaging

Background:

• Accurate imaging of sodium concentration in the dermis is crucial for understanding physiological processes and diagnosing conditions.
• Conventional open electrical impedance tomography (oEIT) methods have limitations in resolving dermal sodium levels.

Purpose of the Study:

• To develop and validate a novel imaging technique, square wave open electrical impedance tomography with spatial voltage thresholding (SW-oEIT with SVT), for quantifying sodium concentration in the dermis.
• To compare the performance of SW-oEIT with SVT against conventional oEIT.

Main Methods:

• The SW-oEIT with SVT method involves three steps: voltage measurement using square wave current, spatial voltage thresholding to isolate the dermis, and sodium concentration imaging via Gauss-Newton reconstruction.
• The technique was applied to multi-layer skin simulations and ex-vivo experiments with varying sodium concentrations (5-50 mM).
• Image evaluation used the determination coefficient (R²) and normalized sensitivity (S) to assess the relationship between spatial mean conductivity and sodium concentration.

Main Results:

• SW-oEIT with SVT successfully imaged spatial mean conductivity distribution in the dermis, correlating with increasing sodium concentrations in both simulations and experiments.
• An optimized threshold distance (dΓ) of 2 mm yielded the highest evaluation values (R²=0.84, S=0.83).
• SW-oEIT with SVT demonstrated a 15.32% higher correlation coefficient (CC) compared to conventional sine wave oEIT.

Conclusions:

• SW-oEIT with SVT is an effective method for imaging dermal sodium concentration.
• The optimized SVT parameter (dΓ=2 mm) enhances imaging accuracy.
• This novel technique offers improved performance over conventional oEIT for sodium concentration imaging in biological tissues.