Tissue characterization based on impedance images and on impedance measurements

• US 5,810,742 A
• Filed: 10/04/1996
• Issued: 09/22/1998
• Est. Priority Date: 10/24/1994
• Status: Expired due to Term

• Current Assignee: Mirabel Medical Systems Ltd. (Ronny Ginor, MD)
• Original Assignee: Trans Research Development Corporation
• Inventors: Pearlman, Andrew L.
• Primary Examiner(s): MANUEL, GEORGE C
• Application Number:
  US08/725,927
• Time in Patent Office: 718 Days
• Field of Search: 600/547, 600/372, 600/382, 600/384, 600/386, 600/461, 600/476, 600/477, 600/478
• US Class Current: 600/547
• CPC Class Codes: A61B 10/0233 Pointed or sharp biopsy instruments
• CPC Class Codes: A61B 17/3403 Needle locating or guiding means guides for suture needles A61B17/0482; guiding or tracking by nuclear magnetic resonance G01R33/285
• CPC Class Codes: A61B 2017/00026 Conductivity or impedance, e.g. of tissue
• CPC Class Codes: A61B 2017/00199 with a console, e.g. a control panel with a display
• CPC Class Codes: A61B 2017/00438 connectable to a finger
• CPC Class Codes: A61B 2017/3413 guided by ultrasound
• CPC Class Codes: A61B 2090/378 using ultrasound
• CPC Class Codes: A61B 2562/0215 Silver or silver chloride containing
• CPC Class Codes: A61B 2562/046 in a matrix array
• CPC Class Codes: A61B 5/0536 Impedance imaging, e.g. by tomography
• CPC Class Codes: A61B 5/6848 Needles
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61B 90/17 for soft tissue, e.g. breast-holding devices
• CPC Class Codes: A61B 90/36 Image-producing devices or illumination devices not otherwise provided for

Abstract

Apparatus for aiding in the identification of tissue type for an anomalous tissue in an impedance image comprising:

means for providing an polychromic immitance map of a portion of the body;

means for determining a plurality of polychromic measures from one or both of a portion of the body; and

a display which displays an indication based on said plurality of polychromic measures.

Claims

1. Apparatus for aiding in the identification of tissue type for an anomalous tissue in an impedance image comprising:

means for providing a polychromic immitance map of a portion of the body;

means for determining a plurality of polychromic measures of an anomalous region of the immitance image; and

a display which displays an indication based on said plurality of polychromic measures.

2. Apparatus according to claim 1 including means for providing a map of said polychromic measures and wherein said indication includes a display of a plurality of said maps.

3. Apparatus according to claim 2 wherein said display includes an overlay of maps of said polychromic measures.

4. Apparatus according to claim 3 and including means for matching the values of the plurality of measures with predetermined values of the measures to identify the tissue type of the anomalous tissue.

5. Apparatus according to claim 4 wherein the values of the measures are normalized values.

6. Apparatus according to claim 4 wherein the indication is the display of a map of said determined tissue type.

7. Apparatus for determining a tissue type for an anomalous tissue comprising:

means for determining a plurality of polychromic measures of the anomalous tissue; and

means for matching the values of the plurality of measures with predetermined values of the measures to identify the tissue type of the anomalous tissue.

8. Apparatus according to claim 7 wherein the values of the measures are normalized values.

9. Apparatus according to claim 7 wherein one of the polychromic measures is derived from the frequency at which the capacitance spectrum of the anomaly crosses a capacitance spectrum of typical nonanomolous regions.

10. Apparatus according to claim 7 wherein one of the polychromic measures is derived from the integrated deviation of the capacitance or conductance of the anomaly from that of typical nonanomolous regions.

11. Apparatus according to claim 10 wherein one of the polychromic measures is derived from the sum, over a plurality of frequencies, of the positive deviations of the capacitance of the anomaly from that of typical nonanomolous regions.

12. Apparatus according to claim 10 wherein one of the polychromic measures is derived from the sum, over a plurality of frequencies, of the negative deviations of the capacitance of the anomaly from that of typical nonanomolous regions.

13. Apparatus according to claim 10 wherein one of the polychromic measures is derived from the sum, over a plurality of frequencies, of the positive deviations of the conductance of the anomaly from that of typical nonanomolous regions.

14. Apparatus according to claim 7 wherein one of the measures is the integral of the phase or the sum of phase values over a range of frequencies.

15. Apparatus according to claim 7 wherein one of the measures is the difference between the integral of the difference between the phase at a point and the mean or median value of the phase in the image, over a range of frequencies.

16. Apparatus according to claim 7 wherein one of the measures is the derivative of the capacitance curve or its logarithm as a function of frequency, evaluated at a given frequency.

17. Apparatus according to claim 7 wherein one of the measures is the derivative of the conductance curve or its logarithm as a function of frequency, evaluated at a given frequency.

18. Apparatus according to claim 7 wherein one of the measures is a frequency at which the phase of the impedance reaches a specified value.

19. Apparatus according to claim 16 wherein the specified value is 45 degrees.

20. A method of determining a tissue type for tissue in an anomalous region in an immitance image, comprising:

determining a plurality of polychromic measures of said anomalous region; and

matching the values of the plurality of measures with predetermined values to identify the tissue type of the anomalous region.

21. A method of determining a tissue type for an anomalous tissue:

determining a plurality of polychromic measures of the anomalous tissue;

matching the values of the plurality of measures with predetermined values to identify the tissue type of the anomalous tissue.

22. A method according to claim 21 wherein one of the polychromic measures is derived from the frequency at which the capacitance spectrum of the anomaly crosses a capacitance spectrum of typical nonanomolous regions.

23. A method according to any of claim 21 wherein one of the polychromic measures is derived from the integrated deviation of the capacitance or conductance of the anomaly from that of typical nonanomolous regions.

24. A method according to claim 23 wherein one of the polychromic measures is derived from the sum, over a plurality of frequencies, of the positive deviations of the capacitance of the anomaly from that of typical nonanomolous regions.

25. A method according to claim 23 wherein one of the polychromic measures is derived from the sum, over a plurality of frequencies, of the negative deviations of the capacitance of the anomaly from that of typical nonanomolous regions.

26. A method according to claim 23 wherein one of the polychromic measures is derived from the sum, over a plurality of frequencies, of the positive deviations of the conductance of the anomaly from that of typical nonanomolous regions.

27. A method according to claim 21 wherein one of the measures is the integral of the phase or the sum of phase values over a range of frequencies.

28. A method according to claim 21 wherein one of the measures is the difference between the integral of the difference between the phase at a point and the mean or median value of the phase in the image, over a range of frequencies.

29. A method according to claim 21 wherein one of the measures is the derivative of the capacitance curve or its logarithm as a function of frequency, evaluated at a given frequency.

30. A method according to claim 21 wherein one of the measures is the derivative of the conductance curve or its logarithm as a function of frequency, evaluated at a given frequency.

31. A method according to claim 21 wherein one of the measures is a frequency at which the phase of the impedance reaches a specified value.

32. A method according to claim 31 wherein the specified value is 45 degrees.

33. A method according to claim 21 wherein the values of the measures are normalized values.

34. A multi-element probe for providing an electrical connection to a tissue surface comprising:

a plurality of individual conductive sensing elements, each having a front portion suitable for contact with the tissue surface;

a plurality of conductive elements providing an electrical connection to the respective individual sensing elements; and

a partition separating the individual sensing elements such that when the individual probes contact the tissue surface they are substantially electrically isolated from each other.

35. A probe according to claim 34 wherein the sensing elements comprise a conductive, viscous gel.

36. A probe according to claim 34 wherein the sensing elements comprise a conductive, flexible, solid.

37. A probe according to claim 34 wherein the sensing elements comprise a sponge impregnated with a conductive viscous gel.

38. A probe according to claim 34 wherein each individual sensing element is located in a well formed by the partition and a substrate underlying the sensing element.

39. A probe according to claim 38 wherein a side of the substrate opposite the sensing elements is formed with an alignment structure for aligning the multi-element probe.

40. A probe according to claim 39 wherein the well is formed by embossing the partition on a sheet of material, whereby the un-embossed portion of the sheet forms the substrate underlying the sensing element.

41. A probe according to claim 39 wherein the well is formed by embossing the partition on a sheet of material, whereby the un-embossed portion of the sheet forms the substrate underlying the sensing element and wherein the indentations are the back of the embossed wells.

42. A probe according to claim 38 wherein the well is formed by laminating a grid formed by holes punched in a sheet or formed by extrusion to the substrate.

43. A probe according to claim 38 wherein the well is formed by printing the partitions onto the substrate.

44. A probe according to claim 38, including an electrical connection between a first surface of the substrate inside the well and a second, opposite, surface of the substrate.

45. A probe according to claim 44 and also comprising an anisotropic conductive sheet overlying the second surface of the substrate.

46. A probe according to claim 44 and also comprising a conductive contact on the second surface of the substrate which is electrically connected to the first surface of the substrate and an adhesive contact overlying the conductive contact.

47. A probe according to claim 34 wherein the partition has a top, and sensing elements do not extend past the top of the partition.

48. A probe according to claim 47 wherein the sensing elements do not extend to the top of the partition.

49. A probe according to claim 34 and including a cover having a conductive surface facing the front portion of the sensing elements.

50. A probe according to claim 34, wherein the sensing elements are formed of a spongy conductive material.

51. A probe according to claim 34, wherein the sensing elements are formed on a flexible surface, whereby the multi-element probe conforms, at least in part, to the tissue.

52. A probe according to claim 34, wherein the probe is provided with apertures between sensing elements suitable for the passage of a thin elongate object.

53. A probe according to claim 34, wherein at least a portion of a surface of the probe facing the tissue to be measured is adhesive to the tissue.

54. A probe according to claim 34, and including means for attaching the probe to the finger of a person whereby the person can perform palpative examination concurrently with impedance imaging.

55. A probe according to claim 34, wherein at least a portion of a surface of the probe facing the tissue to be measured is adhesive to the tissue.

98. A multi-element intermediate device for providing an electrical connection between a multiconductor sensor device and a tissue surface comprising:

a multi-element probe according to any one of claims 34-48, 56-60, 68, 72, 79, 85, 90, 93 or 96, and having a back portion detachably matable to the multi-conductor sensor device.

99. An intermediate device according to claim 98 and including electrical contacts on the back portion which are electrically connected to the sensing element and which contact a plurality of mating contacts on the multi-conductor sensor device.

100. A catheter or endoscopic probe comprising:

a multi-element probe according to any one of claims 34-48, 56-60, 68, 72, 79, or 85; and

a fiber optic viewer whose field of view includes at least one surface of the probe when the probe is in contact with the tissue.

56. A multi-element probe for providing an electrical connection to tissue comprising:

a plurality of individual conductive sensing elements, each having a front portion suitable for contact with the tissue;

a plurality of conductive elements providing an electrical connection to the respective individual sensing elements; and

a cover having a surface facing the front portion of the sensing elements, at least that portion of said surface facing the sensing elements being an electrically conductive surface.

57. A multi-element probe according to claim 56 wherein said cover is formed of a flexible material and wherein, in an unstressed position said electrical conductive surface does not contact said conductive sensing elements.

58. A multi-element probe according to claim 57 wherein said cover is so configured that the surface contacts the sensing elements when a surface of the cover opposite the conductive surface is pressed toward the sensing elements.

59. A multi-element probe according to claim 56 wherein the cover also includes an area, on the surface facing the individual sensing elements, remote from the individual sensing elements, which is a conductive area electrically connected to said portions facing the sensing elements, the multi-element probe also including a contact electrically connected to the exterior of the probe.

60. A multi-element probe according to claim 59 and also including impedance elements between the conductive surfaces opposite the sensing elements and the contact.

61. A multi-element probe according to claim 59 wherein, in an unstressed position, said electrical conductive surface does not contact said contact and wherein said cover is so configured that the conductive area contacts the contact when a surface of the cover opposite the conductive surface is pressed toward the sensing elements.

62. A multi-element probe according to claim 56 and further comprising at least one contact suitable for connection to an external source of electrical energy and also including impedance elements between the conductive surfaces opposite the sensing elements and the contact.

63. A probe according to claim 56, wherein the sensing elements are formed of a spongy conductive material.

64. A probe according to claim 56, wherein the sensing elements are formed on a flexible surface, whereby the multi-element probe conforms, at least in part, to the tissue.

65. A probe according to claim 56, wherein the probe is provided with apertures between sensing elements suitable for the passage of a thin elongate object.

66. A probe according to claim 56, wherein at least a portion of a surface of the probe facing the tissue to be measured is adhesive to the tissue.

67. A probe according to claim 56, and including means for attaching the probe to the finger of a person whereby the person can perform palpative examination concurrently with impedance imaging.

68. A multi-element probe for providing an electrical connection to a tissue surface comprising:

a plurality of individual conductive sensing elements, each having a front portion suitable for contact with the tissue surface; and

a plurality of conductive elements providing an electrical connection to the respective individual sensing elements,

wherein the side of the substrate opposite the sensing elements is formed with indentations for aligning the multi-element probe.

69. A probe according to claim 68, wherein the sensing elements are formed of a spongy conductive material.

70. A probe according to claim 68, wherein the sensing elements are formed on a flexible surface, whereby the multi-element probe conforms, at least in part, to the tissue.

71. A probe according to claim 68, wherein the probe is provided with apertures between sensing elements suitable for the passage of a thin elongate object.

72. A probe according to claim 68, and including means for attaching the probe to the finger of a person whereby the person can perform palpative examination concurrently with impedance imaging.

73. A multi-element probe for the measurement of impedance of tissue, comprising sensing elements which are sufficiently transparent to allow visualization of tissues beneath the probe when the probe is placed in contact with the tissues.

74. A probe according to claim 73, wherein the sensing elements are formed of a spongy conductive material.

75. A probe according to claim 73, wherein the sensing elements are formed on a flexible surface, whereby the multi-element probe conforms, at least in part, to the tissue.

76. A probe according to claim 73, wherein the probe is provided with apertures between sensing elements suitable for the passage of a thin elongate object.

77. A probe according to claim 73, wherein at least a portion of a surface of the probe facing the tissue to be measured is adhesive to the tissue.

78. A probe according to claim 73, and including means for attaching the probe to the finger of a person whereby the person can perform palpative examination concurrently with impedance imaging.

79. A multi-element probe for providing an electrical connection to a tissue surface comprising:

a plurality of individual conductive sensing elements, each having a front portion suitable for contact with the tissue surface; and

a plurality of conductive elements providing an electrical connection to the respective individual sensing elements, wherein

the probe is sufficiently transparent to allow visualization of tissues beneath the probe when the probe is placed in contact with the tissues.

80. A probe according to claim 79, wherein the sensing elements are formed of a spongy conductive material.

81. A probe according to claim 79, wherein the sensing elements are formed on a flexible surface, whereby the multi-element probe conforms, at least in part, to the tissue.

82. A probe according to claim 79, wherein the probe is provided with apertures between sensing elements suitable for the passage of a thin elongate object.

83. A probe according to claim 79, wherein at least a portion of a surface of the probe facing the tissue to be measured is adhesive to the tissue.

84. A probe according to claim 79, and including means for attaching the probe to the finger of a person whereby the person can perform palpative examination concurrently with impedance imaging.

85. A multi-element probe for providing an electrical connection to a tissue surface comprising:

a plurality of individual conductive sensing elements, each having a front portion suitable for contact with the tissue surface; and

a plurality of conductive elements providing an electrical connection to the respective individual sensing elements,

wherein the sensing elements are formed of a spongy conductive material.

86. A probe according to claim 85, wherein the sensing elements are formed on a flexible surface, whereby the multi-element probe conforms, at least in part, to the tissue.

87. A probe according to claim 85, wherein the probe is provided with apertures between sensing elements suitable for the passage of a thin elongate object.

88. A probe according to claim 85, wherein at least a portion of a surface of the probe facing the tissue to be measured is adhesive to the tissue.

89. A probe according to claim 85, and including means for attaching the probe to the finger of a person whereby the person can perform palpative examination concurrently with impedance imaging.

90. A multi-element probe for providing an electrical connection to a tissue surface comprising:

a plurality of individual conductive sensing elements, each having a front portion suitable for contact with the tissue surface; and

a plurality of conductive elements providing an electrical connection to the respective individual sensing elements,

wherein the probe is provided with apertures between sensing elements suitable for the passage of a thin elongate object.

91. A probe according to claim 90, wherein at least a portion of a surface of the probe facing the tissue to be measured is adhesive to the tissue.

92. A probe according to claim 90, and including means for attaching the probe to the finger of a person whereby the person can perform palpative examination concurrently with impedance imaging.

93. A multi-element probe for providing an electrical connection to a tissue surface comprising:

an array of individual conductive sensing elements spaced over a surface, each element having a front portion suitable for contact with the tissue surface; and

a plurality of conductive elements providing an electrical connection to the respective individual sensing elements,

wherein the area of the conductive elements comprises less than 70% of the total area encompassed by the array.

94. A multi-element probe according to claim 93, wherein at least a portion of a surface of the probe facing the tissue to be measured is adhesive to the tissue.

95. A multi-element probe according to claim 93 and including means for attaching the probe to the finger of a person whereby the person can perform palpative examination concurrently with impedance imaging.

96. A multi-element probe for providing an electrical connection to a tissue surface comprising:

a plurality of individual conductive sensing elements, each having a front portion suitable for contact with the tissue surface; and

a plurality of conductive elements providing an electrical connection to the respective individual sensing elements,

wherein at least a portion of a surface of the probe facing the tissue to be measured is adhesive to the tissue.

97. A multi-element probe according to claim 96, and including means for attaching the probe to the finger of a person whereby the person can perform palpative examination concurrently with impedance imaging.

101. Apparatus for impedance imaging of a breast comprising:

a multi-element probe comprising a plurality of sensing elements and adapted for mounting on one side of a breast;

an electrode adapted for mounting on a side of the breast substantially opposite the multi-element probe; and

a source of electrical energy which provides a voltage between at least a portion of the electrode and at least one element of the probe.

102. Apparatus according to claim 109 wherein at least one of the multi-element probes is rigid and non-planar in accordance with the shape of a body structure.

103. Apparatus according to claim 109 wherein at least one of the multi-element probes is flexible so as to conform to the shape of a body structure.

109. Apparatus according to claim 101 wherein the multi-element probe comprises a multi-element probe according to any of claims 34-48, 56-60, 68, 72, 79, 85, 90, 93 or 96.

110. Apparatus according to claim 109 wherein the multi-element probe and the electrode adapted for mounting on a side of the breast form respective parallel planes.

111. Apparatus according to claim 109 wherein the multi-element probe and the electrode adapted for mounting on a side of the breast form two planes at an angle to each other.

112. Apparatus according to claim 109 and including a plurality of receivers which measure an electrical signal at the sensing elements.

113. Apparatus according to claim 109 wherein the electrode adapted for mounting on a side of the breast comprises a second multi-element probe.

104. Apparatus for impedance imaging of a breast comprising:

a first multi-element probe comprising a plurality of sensing elements and adapted for mounting on one side of a breast;

a second multi-element probe adapted for mounting on a side of the breast substantially opposite the multi-element probe; and

a source of electrical energy which alternatively energizes at least some of the elements of one or the other of the first and second multi-element probes by supplying a voltage thereto, wherein the unenergized one of the multi-element probes forms an image based on the voltage applied to the energized probe.

119. Apparatus according to claim 104 wherein the multi-element probe comprises a multi-element probe according to any one of claims 34-48, 56-60, 68, 72, 79, 85, 90, 93 or 96.

120. Apparatus according to claim 104 wherein the first and second multi-element probes form respective parallel planes.

121. Apparatus according to claim 104 wherein the first and second multi-element probes form two planes at an angle to each other.

122. Apparatus according to claim 104 and including a plurality of receivers which measure an electrical signal at the sensing elements.

123. Apparatus according to claim 120 and including a plurality of receivers which measure an electrical signal at the sensing elements.

124. Apparatus according to claim 121 and including a plurality of receivers which measure an electrical signal at the sensing elements.

105. A multi-element probe for providing an electrical connection to a tissue surface comprising:

a plurality of individual conductive sensing elements, each having a front portion suitable for contact with the tissue surface; and

a glove having fingers, said sensing elements being attached to the outside of the glove at one of the fingers whereby a wearer of the glove can perform palpative examination concurrently with impedance imaging.

106. A multi-element intermediate device for providing an electrical connection between a multiconductor sensor device and a tissue surface comprising a plurality of individual conductive sensing elements, substantially electrically insulated from each other, each having a front portion suitable for contact with the tissue surface and a back portion detachably matable to the multi-conductor sensor device.

107. An intermediate device according to claim 106 and including electrical contacts on the back portion which are electrically connected to the sensing element and which contact a plurality of mating contacts on the multi-conductor sensor device.

108. A catheter or endoscopic probe comprising:

a multi-element probe for providing an electrical connection to a tissue surface, the probe including a plurality of individual conductive sensing elements on a substrate, each sensing element having a front portion suitable for contact with the tissue surface and fiduciary marks visible from an other surface; and

a fiber optic viewer whose field of view includes at least the other surface of the probe.

114. Apparatus for impedance imaging of a breast comprising:

a multi-element probe comprising a plurality of sensing elements and adapted for mounting on one side of a breast;

an electrode adapted for mounting on a side of the breast substantially opposite the multi-element probe;

an additional electrode adapted for mounting on portion of the body remote from the breast; and

a source of electrical energy which provides a voltage between the additional electrode and at least one element of the probe.

115. Apparatus according to claim 114 wherein the multi-element probe and the electrode adapted for mounting on a side of the breast form respective parallel planes.

116. Apparatus according to claim 114 wherein the multi-element probe and the electrode adapted for mounting on a side of the breast form two planes at an angle to each other.

117. Apparatus according to claim 114 and including a plurality of receivers which measure an electrical signal at the sensing elements.

118. Apparatus according to claim 114 wherein the electrode adapted for mounting on a side of the breast comprises a second multi-element probe.

125. Apparatus for impedance imaging of tissue comprising:

an impedance probe which produces signals representative of impedance values below the elements and having fiduciary marks which are visible when the probe contacts the tissue;

an impedance image generator which receives the signals and produces an impedance image;

a video camera which views the probe and tissue and generates a video image; and

a video image processor which receives a video image of the tissue without the probe in place and an image of the tissue with the probe in place, and provides a video image of the tissue with the fiduciary marks and impedance image superimposed thereon.

126. A method of impedance imaging of a region of the body comprising:

(a) positioning a multi-element probe, comprising a plurality of sensing elements, on one side of the region;

(b) positioning an electrode on a side of the region substantially opposite the multi-element probe;

(c) electrifying the electrode; and

(d) measuring a signal at at least some of the elements of the multi-element probe.

127. A method according to claim 126 wherein (b) comprises positioning a second multi-element probe on a side of the region substantially opposite the multi-element probe.

128. A method of impedance imaging of a region of the body comprising:

(a) positioning a multi-element probe, comprising a plurality of sensing elements, on one side of the region;

(b) positioning an electrode on a side of the region substantially opposite the multi-element probe;

(c) positioning a second electrode on a portion of the body;

(d) electrifying the second electrode; and

(e) measuring a signal at at least some of the elements of the multi-element probe.

129. A method according to claim 128 wherein (b) comprises positioning a second multi-element probe on a side of the region substantially opposite the multi-element probe.

130. A method of impedance imaging of a region of the body comprising:

positioning a first multi-element probe, comprising a plurality of sensing elements, on one side of the region;

positioning a second multi-element probe on a side of the region substantially opposite the multi-element probe;

electrifying fewer than all of the plurality of sensing elements of the second multi-element probe; and

measuring a signal at at least some of the elements of the first multi-element probe.

131. A method of impedance imaging of a region of the body comprising:

contacting one side of the region with a first multi-element probe, comprising a first plurality of sensing elements;

contacting a second side of the region with a second multi-element probe, comprising a second plurality of sensing elements;

receiving signals from said first and second multi-element probes in response to a stimulus; and

combining the signals received from both probes to locate objects within the region.

132. A method for guidance in the placement of an elongate element in a region of a subject comprising:

(a) inserting the elongate element into tissue, said element including a plurality of impedance measuring sensing element thereon;

(b) measuring the impedance between the plurality of sensing elements and an electrode in contact with the subject; and

(c) guiding the element to a desired position having defined impedance properties in response to measurements of impedance made in (b).

133. A method according to claim 132 wherein the elongate element is inserted into the body through a hole in an array of impedance probe elements and including:

providing a two-dimensional impedance image based on signals received by the array;

guiding the elongate element based on the two-dimensional image; and

determining the desired depth of the elongate element based on impedance signals received from the impedance measuring elements on the elongate element.

134. A method according to claim 132 and also including:

imaging the region of the subject including the elongate element and generating an image thereof,

receiving the image and the measurements of impedance made in (b) and superimposing a representation of the impedance measurements on the image of the elongate element and surrounding tissues; and

displaying said superimposed images.

135. A method according to claim 134 wherein the elongate element is inserted into the body through a hole in an array of impedance probe elements and including:

providing a two-dimensional impedance image based on signals received by the array;

guiding the elongate element based on the two-dimensional image; and

determining the desired depth of the elongate element based on impedance signals received from the impedance measuring elements on the elongate element.

136. A method according to claim 134 wherein the outer surface of the elongate element is formed with a matrix of impedance measuring elements each measuring the tissue impedance in a direction generally perpendicular to the element and wherein the display indicates a guiding direction for the elongate element based on the impedance measurements.

137. A method according to claim 136 wherein the elongate element is inserted into the body through a hole in an array of impedance probe elements and including:

providing a two-dimensional impedance image based on signals received by the array;

guiding the elongate element based on the two-dimensional image; and

determining the desired depth of the elongate element based on impedance signals received from the impedance measuring elements on the elongate element.

138. A method for guidance in the placement of an elongate element in portion of a patient comprising:

forming a first two-dimensional impedance image of at least a part of said portion from a given direction;

forming a second two dimensional impedance image of at least a part of the portion using a multi-element impedance probe placed at a known angle to the plane of the first image;

inserting the elongate element between elements of the multi-element probe; and

guiding the elongate element to a point of impedance deviation at least partially under the guidance of the first and second two dimensional images.

139. A method comprising:

providing an impedance measurement system including a multi-element probe attached to at least one finger of an examiner; and

providing an indication of impedance generated on the basis of signals detected by said elements, whereby both a tactile and impedance indication of an examined tissue are simultaneously acquired.

140. A method for improving the sensitivity of impedance imaging comprising:

contacting tissue with a multi-element probe;

contacting a different portion of tissue with at least one electrode;

exciting the at least one electrode with a pulsed voltage;

measuring signals, responsive to said pulsed voltage at at least a plurality of the elements of the probe;

computing the real and imaginary parts of an admittance represented by said voltage and signals for a plurality of frequencies at a plurality of said elements; and

choosing at least one frequency as a measurement frequency which gives a large difference for said measures at different elements of the probe.

141. A method for identifying, in a multi-element impedance probe which forms an impedance map of tissue when placed on the surface thereof, artifacts among impedance deviations from the surroundings, the method comprising:

manipulating the tissue underlying the probe while the probe remains in stationary contact with the surface of the tissue; and

identifying as a non-artifact those impedance deviations which shift in the direction of the manipulation on the impedance map.

142. A method for identifying, in a multi-element impedance probe which forms an impedance map of tissue when placed on the surface thereof, artifacts among impedance deviations from the surroundings, the method comprising:

moving the probe along the surface of the tissue; and

identifying as an artifact those impedance deviations which remain stationary or disappear in the impedance map as the probe is moved.

143. A method for identifying, in a multi-element impedance probe which forms an impedance map of tissue when placed on the surface thereof, artifacts among impedance deviations from the surroundings, the method comprising:

moving the probe together with the tissue; and

identifying as a fixed artifact those impedance deviations which move on the impedance map, in the opposite direction from the movement of the probe and the tissue.

144. A method of displaying impedance imaging information comprising:

displaying at least one impedance image of a region; and

displaying an indication of the imaged region on a representation of the physiology of the patient.

145. A method of displaying according to claim 144 and including:

simultaneously displaying both a capacitance and a conductance map of the same region.

146. A method of displaying impedance imaging information comprising:

displaying a capacitance map of a region; and

simultaneously displaying a conductance map of the same region.

147. A method of displaying impedance imaging information comprising:

computing maps of a plurality of imaging measures; and

simultaneously displaying the measures.

148. A method of displaying impedance information comprising:

computing a plurality of maps of at least one imaging measure at a plurality of frequencies; and

simultaneously displaying the maps.

149. A method of identifying a suspected carcinoma comprising:

comparing a capacitance map of a region to a conductance map of the same region;

identifying a deviation from the surroundings as a suspected cancer if at some frequency less than about 10 kHz both the capacitance value and the conductance value are higher than that of the surroundings.

150. A method according to claim 149 wherein the frequency at which the comparison of the capacitance and conductance values take place is below 2500 Hz.

151. A method according to claim 149 wherein the frequency at which the comparison of the capacitance and conductance values take place is below 500 Hz.

152. A method of identifying a suspected atypical hyperplasia comprising:

comparing a capacitance map of a region to a conductance map of the same region;

identifying a deviation from the surroundings as a suspected cancer if at some frequency less than 10 kHz both the capacitance value and the conductance value are higher than that of the surroundings.

153. A method according to claim 152 wherein the frequency at which the comparison of the capacitance and conductance values take place is below 2500 Hz.

154. A method according to claim 152 wherein the frequency at which the comparison of the capacitance and conductance values take place is below 500 Hz.

155. A method of differentiating a suspected carcinoma from a suspected atypical hyperplasia comprising:

comparing a capacitance map of a region to a conductance map of the same region;

classifying a deviation from the surroundings as a suspected atypical hyperplasia if at some frequency less than 10 kHz the capacitance value is lower than that of the surroundings and the conductance value is higher than that of the surroundings; and

classifying a deviation from the surroundings as a suspected cancer if at some frequency less than 10 kHz both the capacitance value and the conductance value are higher than that of the surroundings.

156. A method according to claim 155 wherein the frequency at which the comparison of the capacitance and conductance values take place is below 2500 Hz.

157. A method according to claim 155 wherein the frequency at which the comparison of the capacitance and conductance values take place is below 500 Hz.