Abstract: Approaches are disclosed for electrical impedance tomography which apply a current to a region at two or more frequencies and acquire voltage measurements at each frequency to generate a set of multi-frequency voltage measurements. One or more images of the region are generated, using spectral constraints, based on the multi-frequency data.

Abstract: A method is provided for taking electrical impedance tomography measurements using multiple electrodes located at selected positions external to a volume of a subject body. Multiple orthogonal or near-orthogonal signals are introduced simultaneously by way of selected different electrodes and resultant predetermined responses (if any) at receiving electrodes are recorded or determined. The signals are encoded using the technique of code division multiplexing and received signals at each receiving electrode are cross-correlated with original signals to determine the contribution of each original signal to a composite received signal. The invention also relates to apparatus suitable for use in applying a method.

Abstract: Approaches are disclosed for electrical impedance tomography which apply a current to a region at two or more frequencies and acquire voltage measurements at each frequency to generate a set of multi-frequency voltage measurements. One or more images of the region are generated, using spectral constraints, based on the multi-frequency data.

Abstract: An impedance tomography apparatus is disclosed for the measuring of the electrical activity of excitable tissue. The apparatus comprises a plurality of signal transfer devices adapted for transferring an input signal to a body and receiving an output signal from a body. An input signal generator is adapted to generate an electrical input signal and apply it to at least one of the signal transfer devices. A measurement device is arranged to measure the output signal from the body at least one or more of the remaining signal transfer devices, wherein the input signal generator is adapted to generate an input signal of frequency greater than 100 Hz and less that 5 kHz. This allows the depolarisation of nervous or muscle tissue to be imaged.

Abstract: A method is provided for taking electrical impedance tomography measurements using multiple electrodes located at selected positions external to a volume of a subject body. Multiple orthogonal or near-orthogonal signals are introduced simultaneously by way of selected different electrodes and resultant predetermined responses (if any) at receiving electrodes are recorded or determined. The signals are encoded using the technique of code division multiplexing and received signals at each receiving electrode are cross-correlated with original signals to determine the contribution of each original signal to a composite received signal. The invention also relates to apparatus suitable for use in applying a method.

Abstract: A method and apparatus for use in imaging a body uses electrical impedance tomography (EIT). A plurality of electrodes are provided in electrical contact with the body around the periphery of the body. A first electrical input signal is applied to at least one of the electrodes over a first time period, and a second electrical input signal, which is preferably in inverted form of the first, then applied to the at least one of the electrodes over a subsequent, second time period. The resulting electrical output signal is measured at one or more pairs of the remaining electrodes over the first and second time periods and the difference between the measured signal obtained during the first time period and that obtained during the second time period is calculated to provide a difference signal. The difference signal can stored and used for image reconstruction.