Broadband quasi-differential multifrequency electrical impedance imaging system

Area of Science:

• Electrical Impedance Tomography
• Biomedical Imaging
• Signal Processing

Background:

• Multifrequency imaging methods enable visualization of static structures within objects.
• Data acquisition systems can introduce errors due to non-ideal frequency responses.
• Quasi-static or quasi-differential imaging is needed when impedance changes are small, mimicking dynamic imaging scenarios.

Purpose of the Study:

• To develop and evaluate a quasi-differential imaging method for static structure visualization.
• To design and construct an instrument capable of multifrequency data acquisition.
• To address limitations of existing imaging techniques by minimizing frequency-related errors.

Main Methods:

• Designed and built an instrument for signals from 1 kHz to 1 MHz with 10 Hz increments.
• Engineered patient interface circuits and demodulators for a flat frequency response.
• Utilized 16-bit signal digitization and a high-speed serial interface for data transfer.
• Achieved a maximum imaging speed of approximately 8 images/s.

Main Results:

• The developed instrument operates across a broad frequency spectrum (1 kHz–1 MHz).
• System components were thoroughly characterized to define operational limits.
• The system demonstrated suitability for quasi-static and quasi-differential imaging data collection.

Conclusions:

• The quasi-differential imaging method offers a viable approach for imaging static structures.
• The designed instrument provides a robust platform for multifrequency impedance imaging.
• Characterization data guides the application of the system within its performance boundaries.