Quantification of blood volume by electrical impedance tomography using a tissue-equivalent phantom

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Electrical Impedance Tomography

Background:

• Accurate estimation of intra-peritoneal blood requires an electrical impedance tomography (EIT) system with responses independent of anomaly position.
• Existing EIT systems may face challenges with positional variations of high conductivity anomalies, such as blood, within the abdominal cavity.

Purpose of the Study:

• To design and assess an in vivo EIT system for accurate intra-peritoneal blood quantity estimation.
• To minimize the system's response dependency on the position of intra-peritoneal blood anomalies.

Main Methods:

• Utilized a cylindrical tissue-equivalent phantom to assess system sensitivity to blood-equivalent resistivity anomalies.
• Employed filtering of resistivity profile images and extended electrodes for data acquisition.
• Developed a 'resistivity index' and applied a correction filter to mitigate radial variations.

Main Results:

• Satisfactorily uniform system response in both radial and axial directions was achieved through image filtering and extended electrodes.
• The correction filter reduced a 30% resistivity index variation (at 0.75 phantom radius) to only 6%.
• Extended electrodes reduced axial position variation in the resistivity index by approximately half compared to small circular electrodes.

Conclusions:

• The developed EIT system, incorporating image filtering and extended electrodes, demonstrates improved accuracy for intra-peritoneal blood detection.
• The resistivity index and correction filter effectively address positional variations, enhancing the reliability of blood quantity estimation.
• This approach offers a more robust solution for in vivo EIT applications requiring precise localization and quantification of internal anomalies.