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Non-invasive electromagnetic technique for monitoring physiological changes in the brain

  • US 4,690,149 A
  • Filed: 10/28/1985
  • Issued: 09/01/1987
  • Est. Priority Date: 10/28/1985
  • Status: Expired due to Term
First Claim
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1. A method for locating edematous tissue within the white or grey matter of an animal or human brain, comprising:

  • noninvasively detecting the impedance due to brain tissue and other biological matter at a plurality of localized portions within the brain, wherein said detecting step for each of said plurality of localized portions comprises the steps of;

    a. producing an oscillating magnetic field that is spatially concentrated in a localized portion of a brain using a coil means, whereby eddy currents induce a secondary magnetic emission which alters the mutual inductance of said coil means in accordance with the impedance of brain tissue and other biological matter in said portion, andb. measuring a change in the mutual inductance of said coil means, wherein an increase in mutual inductance indicates an increase in impedance and a decrease in mutual inductance indicates a decrease in impedance; and

    ,comparing the impedance detected at each portion of the brain to determine the location of higher impedance regions within the white or grey matter of the brain that indicate the location of edematous tissue.

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