David Holder

Biography or Other Information: 
Department of Medical Physics and Bioengineering, University College London.


  • 2014-04-24
    The potential of Electric Impedance Tomography (EIT) for localising seizure foci was examined in a rat model of epilepsy. The known seizure focus was successfully imaged, which appeared as a transient (~10 ms) decrease in impedance during spikes – due to the opening of ion channels, followed by a gradual increase in impedance as cells swelled.

  • 2014-04-24
    The construction of an EIT system using a commercially available current source and EEG amplifier is discussed. The Keithley 6221 current source offers functionality equivalent to that of existing bespoke systems, alongside the ease of use of a commercial system. When combined with a BioSemi EEG amplifier, a full EIT system is produced. Analysis of the signal quality of the source and imaging experiments on a saline tank verify the feasibility of the approach.

  • 2014-04-25
    We present an application of a newly developed fast parallel EIT forward solver (PEITS) implemented in C++. Its features are summarised and the installation, configuration and interface to Matlab are demonstrated. An application of the solver to a feasibility study of stroke type differentiation is illustrated. We found that precise positioning of the electrodes is critical for obtaining good images of stroke.