Surgery – Diagnostic testing – Structure of body-contacting electrode or electrode inserted...
Reexamination Certificate
2001-10-22
2004-09-07
Cohen, Lee S. (Department: 3739)
Surgery
Diagnostic testing
Structure of body-contacting electrode or electrode inserted...
C600S373000, C600S393000, C600S547000
Reexamination Certificate
active
06788966
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to systems for tissue characterization based on impedance measurements, and in particular to systems for skin cancer characterization.
BACKGROUND OF THE INVENTION
Skin cancer, such as melanoma, Basal cell carcinoma (BCC), Squamous cell carcinoma (SCC), is a type of cancer which afflicts many people. Early detection of skin cancer dramatically increases the probability of successful removal of the skin cancer. Conventional methods of skin cancer detection include visual inspection of suspected skin moles for characteristics of malignant tumors. These characteristics include asymmetry (i.e., one half of the mole does not match the other half), border irregularity (i.e., the edges are of the mole are ragged, notched or blurred), color (i.e., the pigmentation of the mole is not uniform) and diameter (i.e., the mole has a diameter greater than 6 millimeters) and are referred to together as the ABCD test. When a mole is identified as suspicious, a biopsy sample is taken for a more definite analysis. The percentage of positive cancer indications in melanoma biopsy tests is currently very low, i.e., less than 1%. In order to reduce the number of unnecessary biopsies, and to increase the rates of early identification of melanoma, a non-invasive method for identification of skin cancer, more objective and accurate than the ABCD test, is required.
In some cases, cameras are used to capture images of suspicious skin lesions, to allow follow up of the lesion. Images of a lesion are taken from different distances, chosen as a compromise between the accuracy achieved from being very close to the skin and the capturing a wide view of the surroundings by being very far from the skin. There exists, for example, a system which includes a pair of cameras for imaging skin lesions. A first camera is used for close-up images, and a second camera is used for various other distances farther from the skin.
Variations in electrical impedance have been suggested for use in detection of anomalies and various types of cancer, particularly breast cancer. For example, U.S. Pat. Nos. 4,291,708, 4,458,694, and 5,810,742 and the article, “Breast Cancer Screening by Impedance Measurements,” by G. Piperno et al., Frontiers Med. Biol. Eng., Vol. 2 pp. 111-117, the disclosures of which are incorporated herein by reference, describe systems for determining the impedance between a point on the surface of the skin and some reference point on the body of the patient. With the use of a multi-element probe, a two-dimensional impedance map of an organ such as a breast can be generated. The impedance map, describing variations in impedance along the tissue of the organ, can be used for the detection of tumors and especially malignant tumors.
U.S. Pat. No. 4,291,708 to Frei, mentioned above, describes a probe for placement on a surface being imaged. A plurality of generally flat sensing elements are mounted on the probe in a generally planar arrangement or in a configuration fitting to the human breast.
UK patent application GB 2 276 326, filed Mar. 22, 1994, the disclosure of which is incorporated herein by reference, describes a bio-signal electrode which has a rough surface in order to improve the contact with the skin. Points of the rough surface penetrate the epidermal layer of the skin.
UK patent application GB 2 138 148, filed Apr. 13, 1984, the disclosure of which is incorporated herein by reference, describes mounting of electrodes on respective pneumatic or hydraulic cylinders which keep the electrodes at a common pressure level relative to the skin.
U.S. Pat. No. 5,353,802 to Ollmar, the disclosure of which is incorporated herein by reference, describes a device for depth selective measurement of impedance in the human body. The device is suggested for detection and characterization of surface phenomena in organic and biological material.
U.S. Pat. No. 6,026,323 to Skadlev, the disclosure of which is incorporated herein by reference, describes an instrument for detection of cervical cancer and other surface cancers. The instrument combines optical and electrical devices, which perform complex tests on the cervix of a patient and on other surfaces of a patient such as the skin. The instrument of the U.S. Pat. No. 6,026,323 patent includes three electrodes, which are used to sense the local impedance at the point of contact of the electrodes.
SUMMARY OF THE INVENTION
An aspect of some embodiments of the present invention relates to an electrode head that holds one or more bio-compatible electrodes for in vivo impedance imaging. The electrode head comprises a rigid electrode head formed of one or more PCBs (printed circuit boards) on which the electrodes are mounted. In some embodiments of the invention, the rigid electrode head is formed of one or more rigid PCBs. Alternatively, the electrode head is formed of a plurality of PCBs, at least one of which is a flexible PCB, which are stiffened by their attachment. Generally, a rigid electrode head does not conform to the shape of a surface against which it is pressed. The use of a rigid electrode head ensures that the relative orientation of electrodes mounted on the electrode head is known and/or planar. Therefore, generation of an image from signals sensed by the electrodes is simpler relative to use of flexible PCBs. Also, a rigid electrode head serves as a more solid base for electrodes adapted to penetrate a tissue surface of a patient, as described hereinbelow for some embodiments of the invention.
In some embodiments of the invention, the one or more electrodes are mounted on one or more edges of the one or more PCBs. Optionally, the electrode head comprises a plurality of PCBs which are attached with their surface areas (i.e., faces) facing each other.
An aspect of some embodiments of the present invention relates to an electrode head including one or more electrodes protruding from one or more edges of the one or more PCBs. In some embodiments of the invention, the one or more electrodes comprise ends of conductive wires running along one or more of the PCBs. In some embodiments of the invention, the electrodes have an axis parallel to the surface of the PCB, such that the electrode contacts the skin of a patient axially. Optionally, the electrodes extend beyond the edge of the PCB. In some embodiments of the invention, the electrodes comprise sharp points, which penetrate the stratum corneum of the skin surface, without penetrating the epidermal layer. Optionally, the sharp points penetrate to a depth of between about 30-50 &mgr;m.
An aspect of some embodiments of the present invention relates to an electrode head that includes a plurality of PCBs permanently combined. Optionally, the PCBs are combined along their faces. In some embodiments of the invention, each of the PCBs is connected to at least one neighboring PCB such that at least part of the face area of the PCB covers most of the face area of the neighboring PCB.
An aspect of some embodiments of the present invention relates to a bio-medical probe including one or more sensing elements. The probe does not allow sensing of electrical signals, unless a physician presses the probe against the tissue surface with at least a minimal predetermined force. Optionally, not allowing the sensing of the electrical signals comprises not applying a stimulus signal required for sensing the signals. Alternatively or additionally, not allowing the sensing of the electrical signals comprises disconnecting a sensing circuit from the one or more sensing elements and/or marking acquired signals as invalid. Further alternatively or additionally, not allowing the sensing of the electrical signals comprises preventing contact between the sensing elements and an inspected tissue surface. In some embodiments of the invention, the probe includes a stopper which constrains the advancement of the sensing elements toward the tissue surface unless the minimal force is applied. The stopper is optionally mounted on a pressure exerting device, e.g., springs, pneumatic devices, hy
Filo Orna
Glickman Yael Agi
Kenan Gad
Carella, Byne, Bain, Gilfillan et al.
Cohen Lee S.
Olstein Elliot M.
Squire William
TransScan Medical Ltd.
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