Fast EIT data acquisition system with active electrodes and its application to cardiac imaging

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Electrical Engineering

Background:

• Electrical Impedance Tomography (EIT) is a non-invasive imaging technique.
• Dynamic imaging requires high-speed data acquisition systems.
• Previous systems may have limitations in speed and electrode configuration.

Purpose of the Study:

• To describe a wide-band high-speed data acquisition system for EIT.
• To enable dynamic and multifrequency EIT (MFEIT) imaging of the human thorax.
• To correlate reconstructed conductivity images with physiological activities like cardiac cycles.

Main Methods:

• A 32-active-electrode system with separate receive and drive electrodes was developed.
• Sequential current injection into adjacent electrode pairs and adjacent voltage measurements were performed.
• Operating frequencies ranged from 24 kHz to 400 kHz, with data acquisition per frame completed in 25 ms.
• Electrocardiography (ECG) was recorded concurrently.

Main Results:

• The system was successfully used to image conductivity distribution variations in the human thorax.
• Beat-by-beat cardiac-related conductivity changes were visualized.
• Quasi-periodic impedance variations corresponding to breathing (breath-holding) were observed in image sequences.

Conclusions:

• The developed high-speed EIT system is capable of dynamic imaging of thoracic conductivity.
• The system can capture rapid physiological changes, including cardiac activity and respiration.
• This technology holds potential for advanced medical diagnostics and monitoring.