Mason, Kai;
(2024)
Magnetic Detection Electrical Impedance Tomography for Functional Neural Imaging.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
Fast neural electrical impedance tomography (EIT) is a method for imaging neural activity in the brain or nerve with a resolution of milliseconds and millimetres. Fast neural magnetic detection EIT (MDEIT) is a novel method akin to EIT, utilising the measurement of the magnetic field instead of the electrode voltage. This work has addressed the development of MDEIT computation- ally and experimentally for non-invasive imaging of neural activity in the human brain. Chapters 2 and 3 focus on the computational implementation, optimisation, prediction and assessment of MDEIT. The modelling suggested that although MDEIT would produce a smaller signal-to-noise ratio than EIT, the image quality would be superior with MDEIT. This provided a rationale to undertake experimental MDEIT studies in Chapters 4 and 5. Chapter 4 addressed the characterisation of three magnetometer systems for MDEIT and the imaging of conductivity phantoms. The QuSpin OPM was found to perform well and was used successfully for two-dimensional studies with conductivity phantoms. The commercial Yokogawa SQUID system was unsuitable for use with MDEIT due to instability. The PTB SQUID system was deemed the most suitable for in vivo studies and performed the best by all metrics. Chapter 5 considered the use of the PTB SQUID system to measure the MDEIT signal from auditory evoked potentials in vivo. No reliable signal that was clearly associated with neural activity could be measured. Chapter 6 addressed the development of an image post-processing method for EIT and MDEIT. This improved image quality in all cases. Overall, the results at this time do not suggest that fast neural MDEIT throughout the brain will be possible. However, future studies are required to confirm this, and there are other potential biomedical applications of MDEIT.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Magnetic Detection Electrical Impedance Tomography for Functional Neural Imaging |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2024. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| Keywords: | Electrical impedance tomography, Neural imaging, Magnetometry, Superconducting quantum interference device, Optically pumped magnetometer, Electrophysiology |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Engineering Science Faculty Office |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10199692 |
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