Alistair Boyle

University of Ottawa · School of Human Kinetics

Significance: The movement or incorrect placement of electrodes may lead to modelling errors that result in significant reconstructed image artifacts. These errors may be accounted for by allowing for electrode position estimates in the model. Movement may be reconstructed through a first-order approximation, the electrode position Jacobian. A rec...

Electrical impedance tomography (EIT) measures the conductivity distribution within an object based on the current applied and voltage measured at surface electrodes. Thus, EIT images are sensitive to electrode properties (i.e. contact impedance, electrode area and boundary shape under the electrode). While some of these electrode properties have b...

Electrical Impedance Tomography (EIT) uses measurements from surface electrodes to reconstruct an image of the conductivity of the contained medium. However, changes in measurements result from both changes in internal conductivity and changes in the shape of the medium relative to the electrode positions. Failure to account for shape changes resul...

Electrical impedance tomography (EIT) is a soft field tomography modality based on the application of electric current to a body and measurement of voltages through electrodes at the boundary. The interior conductivity is reconstructed on a discrete representation of the domain using a finite-element method (FEM) mesh and a parametrization of that...

Electrical resistivity images supply information on sub-surface structures and are classically performed to characterize faults geometry. Here we use the presence of a tunnel intersecting a regional fault to inject electrical currents between surface and the tunnel to improve the image resolution at depth. We apply an original methodology for defin...

Objective: Electrical Impedance Tomography (EIT) typically reconstructs individual images from electrical voltage measurements at pairs of electrodes due to current driven through other electrode pairs on a body. EIT images have low spatial resolution, but excellent temporal resolution. There are four methods for integrating temporal data into an...

Electrical impedance tomography (EIT) is a medical imaging technique that uses electrical stimulations and measurements at body‐surface electrodes. From these data, images of the distribution of conductivity within the body are calculated by solving an inverse problem. EIT has the advantage of producing high temporal resolution data, while being re...

Objective: Two main functional imaging approaches have been used to measure regional lung perfusion using electrical impedance tomography (EIT): venous injection of a hypertonic saline contrast agent and imaging of its passage through the heart and lungs, and digital filtering of heart-frequency impedance changes over sequences of EIT images. This...

In the context of aquifer thermal energy storage, we conducted a hydrogeophysical experiment emulating the functioning of a groundwater heat pump for heat storage into an aquifer. This experiment allowed the assessment of surface electrical resistivity tomography (ERT) ability to monitor the 3D development over time of the aquifer thermally affecte...

Proceedings of the 19th International Conference on Biomedical Applications of ELECTRICAL IMPEDANCE TOMOGRAPHY Edited by Alistair Boyle, Nick Polydorides and Jiabin Jia June 11–13, 2018 University of Edinburgh Edinburgh, Scotland, UK

Electrical resistivity tomography (ERT) is increasingly being used to investigate unstable slopes and monitor the hydrogeological processes within. But movement of electrodes or incorrect placement of electrodes with respect to an assumed model can introduce significant resistivity artefacts into the reconstruction. In this work, we demonstrate a j...

Electrical Impedance Tomography (EIT) uses electrical stimulation and measurement at the body surface to image the electrical properties of internal tissues. It has the advantage of non-invasiveness and high temporal resolution but suffers from poor spatial resolution and sensitivity to electrode movement and contact quality. EIT can be useful to a...

text: a. Introduction In EIT, the 2.5D approximation is a method of reducing a 3D forward modelling problem to a 2D problem. We show that (a) the 2D modelling errors can be important, particularly for half-space like configurations (breast and prostate imaging, for example), and (b) that due to stimulus pattern sensitivity, the finite limit in the...

Impedance imaging is a technique where stimulus currents are applied through electrodes to a body or the ground and measurements of the potential at other electrodes are collected. The data, along with any available prior information, are used to reconstruct an image of the conductivity distribution throughout the interior which provides diagnostic...

Four methods for estimating the electrode movement Jacobian were compared under a range of simulation conditions using the Finite Element Method (FEM). Mesh density, electrode diameter and contact impedance were varied over orders of magnitude and the results were plotted to demonstrate the points of agreement and illustrate numerical instabilities...

The performance of an EIT system is determined by its ability to detect contrasting changes in a Region of Interest (ROI) (the sensitivity), while not being sensitive to those outside the ROI (the specificity). We propose a framework to measure system performance and show that this can be implemented as a minimax function over a Fisher linear discr...

This paper announces the release of version 3.8 of the EIDORS software suite. We review its new features, and discusses recent successes and challenges.

The underground platform of Tournemire (Aveyron, France) presents the opportunity to perform in-situ experiments to evaluate the potential of geophysical methods to detect and characterize the presence of discontinuities in the sub-surface. In this work, we apply transmission electrical resistivity tomography to image the medium surrounding a regio...

In the context of nuclear waste storage, low permeability clays are investigated as potential geological barrier. Discontinuities in such formations might facilitate the radionuclide transport to the environment. The underground experimental platforms of Tournemire (Aveyron, France) and Mont Terri (Jura, Switzerland) present the opportunity to perf...

Electrical impedance tomography (EIT) creates tomographic images from surface electrical stimulation and measurement. Many research and commercial devices have been made, with correspondingly many data formats, which negatively impacts the ability to share data. To address this issue, we have developed the OEIT data format, an XML-based flexible co...

A technique for monitoring slope stability in a geological setting through impedance tomography is demonstrated. An iterative absolute Gauss-Newton solver simultaneously constructs estimates of the underground re-sistivity distribution and movement of the stimulation and measurement electrodes. The results are a step toward demonstrating that a cos...

Steam-assisted gravity drainage (SAGD) is a technique that has been developed to efficiently extract bitumen from deep reservoirs. We propose using electrical impedance tomography (EIT) for real-time monitoring of SAGD wells to maintain optimal operating conditions. Several electrode configurations along the pipelines and measurement strategies are...

Distinguishability criteria incorporating stimulation and measurement patterns as well as an initial conductivity distribution over a specific domain were used in combination with linear programming. The outcomes were stimulation and measurement patterns that maximize the mini-mum distinguishability to give a robust experimental design. Specific ap...

There are a number of interesting problems that could be tackled if the computing capacity of current EIT systems can be improved. We examined the performance of two such systems and found that a noticeable portion of the compute time is spent in finding the solution of sparse matrices. We developed and used a new sparse matrix testbench, Meagre-Cr...

Electrical Impedance Tomography (EIT) applies current and measures the resulting voltage on the surface of a target. In biomedical applications, this current is applied, and voltage is measured through electrodes attached to the surface. Electrode models represent these connections in the reconstruction, but changes in the contact impedance or boun...

Electrical Impedance Tomography (EIT) is a method of obtaining images of interior conductivity from electrode measurements on the boundary. Using EIT, this work focuses upon boundary movement in the two-dimensional reconstruction problem. Investigations were carried out using the tools of the Finite Element Method (FEM), inverse problem theory, and...

Artifacts in the images created using Electrical Impedance Tomography (EIT) due to movement of the boundary in difference imaging have been an issue, particularly in pulmonary EIT where chest movement due to breathing and posture change is a regular event.[1] With the recent development of algorithms to detect some types of boundary movement direct...

Electrical Impedance Tomography (EIT) uses the difference in measurements between surface electrodes to reconstruct an image of the conductivity of the contained medium. However, changes in measurements result from changes in internal conductivity and changes in the shape of the medium relative to the electrode positions. Failure to account for sha...