Electrical Impedance Tomography for Perfusion Imaging and Monitoring

Electrical impedance tomography (EIT) is a medical imaging technology that uses boundary electrodes to inject stimulus currents and measure the resulting potential distributions. These potentials are measured using electrodes which are in turn used to reconstruct conductivity changes within the body. EIT has been studied for its ability to image both the flow of blood and the delivery of blood to a tissue (perfusion). However, cardiac-related signals are challenging to image accurately due to their small amplitude and the limited sensitivity of EIT systems to impedance changes deep in the body. This thesis presents techniques to improve perfusion imaging with EIT by generating more accurate meshes and using internal electrodes to obtain higher sensitivity in the centre of the body. This work develops a tool to generate accurate, customized meshes from diagnostic computed tomography (CT) images, and a technique to reconstruct images with internal electrodes. Custom models reconstructed the location of impedance changes due to ventilation with higher accuracy, and internal electrodes yielded an increase in internal sensitivity over traditional external configurations. Shifting the position of electrodes on an internal probe by as little as 1% of the tank radius in simulation created artefacts in images reconstructed using existing approaches without motion correction. A novel technique to correct for probe motion is presented that improved reconstruction accuracy and reduced background noise compared to existing techniques. The presented work contributes to increasing internal sensitivity of EIT measurements and demonstrates that refined meshes and internal electrodes may improve measures of perfusion and help to make EIT a viable tool for continuous perfusion monitoring at the bedside.

Name thesis:degree_name

Doctor of Philosophy (Ph.D.)

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Engineering, Biomedical

Grantor dc:publisher

Carleton University

Year dc:date.issued

2021

Author dc:creator

• Stowe, Symon George Allan

Statement dc:rights

• Copyright © 2021 the author(s). Theses may be used for non-commercial research, educational, or related academic purposes only. Such uses include personal study, research, scholarship, and teaching. Theses may only be shared by linking to Carleton University Institutional Repository and no part may be used without proper attribution to the author. No part may be used for commercial purposes directly or indirectly via a for-profit platform; no adaptation or derivative works are permitted without consent from the copyright owner.

Language dc:language.iso

en

DOI

10.22215/etd/2021-14684

OAI identifier oai:identifier

oai:carleton.scholaris.ca:20.500.14718/41162