eprintid: 10098793
rev_number: 8
eprint_status: archive
userid: 695
dir: disk0/10/09/87/93
datestamp: 2020-05-27 18:15:08
lastmod: 2020-05-27 18:15:08
status_changed: 2020-05-27 18:15:08
type: thesis
metadata_visibility: show
creators_name: Gamba, Humberto Remigio
title: Measurement of Electrical Current Density Distribution within the tissues of the head by Magnetic Resonance Imaging
ispublished: unpub
keywords: Applied sciences; Electrical current; Nuclear magnetic resonance
note: Thesis digitised by ProQuest.
abstract: in vivo and in vitro images of the distribution of electrical current inside the head of newborn piglets that arise from electrodes placed on the top of the head and in the root of the mouth are presented in this thesis. The images are obtained from the magnetic field induced by the electrical current propagating inside the head which is measured using nuclear magnetic resonance (NMR) phase images. From the phase images the electrical current images are then calculated using Ampere's law. Following a review of the NMR principles, the technique of measuring electrical current by NMR is described in detail. The implementation of the technique was then validated with both numerical simulations and experiments with a cylindrical and a cubical phantom. The sources of noise in the NMR data are also reviewed and their effect in the calculated current images is analysed both theoretically and experimentally using the phantoms. From the current images, preferential paths used by the electrical current in passing from the electrode under the neck to the electrode on the top of the head could be identified. The total current per region in the head is determined by segmenting the NMR intensity image and integrating the current through each region. Remarkable differences in the current distribution between the in vivo and post mortem experiment were found. The piglet head inclination during the in vivo experiment was also found to affect the current orientation. It was thought that this effect might be related to a shift in blood volume or flow when the head is inclined, and some evidence for such a change in blood volume, measured using near infrared spectroscopy is presented.
date: 1996
oa_status: green
full_text_type: other
thesis_class: doctoral_open
thesis_award: Ph.D
language: eng
thesis_view: UCL_Thesis
primo: open
primo_central: open_green
verified: verified_manual
full_text_status: public
pages: 233
institution: UCL (University College London)
department: Department of Medical Physics and Bioengineering
thesis_type: Doctoral
citation:        Gamba, Humberto Remigio;      (1996)    Measurement of Electrical Current Density Distribution within the tissues of the head by Magnetic Resonance Imaging.                   Doctoral thesis  (Ph.D), UCL (University College London).     Green open access   
 
document_url: https://discovery-pp.ucl.ac.uk/id/eprint/10098793/1/10045488.pdf