Surgery – Diagnostic testing – Measuring electrical impedance or conductance of body portion
Patent
1997-12-19
1999-07-06
Smith, Ruth S.
Surgery
Diagnostic testing
Measuring electrical impedance or conductance of body portion
A61B 505
Patent
active
059191422
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.
REFERENCES:
patent: 5272624 (1993-12-01), Gisser et al.
patent: 5465730 (1995-11-01), Zadehkoochak et al.
D. S. Holder, "Electrical Impedance Tomography with Cortical or Scalp Electrodes During Global Cerebral Ischaemia in the Anaesthetised Rat", Clin. Phys. Physiol. Meas., 1992, vol. 13, No. 1, pp. 87-98.
R. Guardo et al., "A Superheterodyne Serial Data Acquisition System for Electrical Impedance Tomography", Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, vol. 15, Oct. 1993, pp. 86-87.
K. Boone et al., "Imaging of Cortical Spreading Depression by EIT: Implications for Localization of Epileptic Foci", Physiol. Meas. 15, 1994, pp. A189-A198.
D. S. Holder, "Impedance Changes During the Compound Nerve Action Potential: Implications for Impedance Imaging of Neuronal Depolarisation in the Brain", Medical & Biological Engineering & Computer, No. 2, Mar. 1992, pp. 140-146.
D. C. Barber et al., "Applied Potential Tomography", J. Phys. E: Sci. Instrum., vol. 17, 1984, The Institute of Physics, pp. 723-733.
D. S. Holder, Impedance Changes During Evoked Nervous Activity in Human Subjects: Implications for the Application of Applied Potential Tomography (APT) to Imaging.
Boone Kevin Graham
Holder David Simon
BTG International Limited
Smith Ruth S.
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