Electrical impedance tomography method and apparatus
First Claim
1. A method for use in imaging a body by means of the technique of electrical impedance tomography (EIT), the method comprising:
- providing a plurality of electrodes in electrical contact with the body around the periphery of the body;
applying a stimulus to the body;
applying a first electrical input signal to at least one of the electrodes over a first time period;
applying a second electrical input signal to the at least one of the electrodes over a subsequent, second time period, wherein the second signal is an inverted form of the first electrical input signal;
measuring the resulting electrical output signal at one or more pairs of the remaining electrodes over the first and second time periods; and
calculating the difference between the measured signal obtained during the first time period and that obtained during the second time period, to provide a difference signal.
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Accused Products
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. The invention has particular application in imaging neurological function within the body, where the impedance changes associated with neuronal depolarizations are very small and the resulting electrical signals measured at the body periphery are even smaller. By use of this technique electrical signals corresponding to the dynamic components of impedance change can be reinforced whilst those corresponding to other unwanted components can be cancelled.
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Citations
9 Claims
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1. A method for use in imaging a body by means of the technique of electrical impedance tomography (EIT), the method comprising:
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providing a plurality of electrodes in electrical contact with the body around the periphery of the body; applying a stimulus to the body; applying a first electrical input signal to at least one of the electrodes over a first time period; applying a second electrical input signal to the at least one of the electrodes over a subsequent, second time period, wherein the second signal is an inverted form of the first electrical input signal; measuring the resulting electrical output signal at one or more pairs of the remaining electrodes over the first and second time periods; and calculating the difference between the measured signal obtained during the first time period and that obtained during the second time period, to provide a difference signal. - View Dependent Claims (2, 3, 4, 5, 6)
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7. Apparatus for use in imaging a body suitable for use in the technique of electrical impedance tomography (EIT), the apparatus comprising:
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a plurality of electrodes adapted for electrical contact with the body around the periphery of the body; means for applying a first electrical input signal to at least one of the electrodes over a first time period; means for applying a stimulus signal to the body; means for providing an inverted form of the first electrical signal to produce the second electrical signal; means for applying the second electrical input signal to the at least one of the electrodes over a second, subsequent time period; means for measuring the resulting electrical output signals at one or more pairs of the remaining electrodes over the first and second time periods; and means for calculating the difference between the measured signal obtained during the first time period and that obtained during the second time period, to provide a difference signal. - View Dependent Claims (8, 9)
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Specification