WO2011080652A1

WO2011080652A1 - A method and device for measuring electromagnetic signals of a tissue

Info

Publication number: WO2011080652A1
Application number: PCT/IB2010/055901
Authority: WO
Inventors: Dayu Chen; Hua Jin; Ming Yan; Hui Liu
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2009-12-30
Filing date: 2010-12-17
Publication date: 2011-07-07

Abstract

The invention provides a device and method for measuring electromagnetic signals of a tissue. The device (1) comprises at least two exciting coils (21) for generating a primary magnetic field for the tissue, and adjacent exciting coils (21) of each pair of exciting coils have opposite current flow, so that a distribution of the primary magnetic field is localized around the at least two exciting coils (21). The device (1) also comprises at least one receiving coil (22) for receiving electromagnetic signals induced by a secondary magnetic field, and the secondary magnetic field is generated by the tissue in response to the primary magnetic field.

Description

A METHOD AND DEVICE FOR MEASURING ELECTROMAGNETIC

SIGNALS OF A TISSUE

FIELD OF THE INVENTION

The invention relates to a method and device for measuring a tissue, in particular, to a method and device for measuring electromagnetic signals of a tissue.

BACKGROUND OF THE INVENTION

Electromagnetic signals of a tissue (e.g. of a human or animal body) comprise some important property information of the tissue. A well known technique is developed to measure water content of skin by measuring electromagnetic signals of the skin, and the electromagnetic signals are measured by placing a conventional electrode device on the skin. The conventional electrode device comprises an exciting coil, such as a dipole coil, for generating a primary magnetic field and applying it to the skin, and a receiving coil for receiving electromagnetic signals induced by a secondary magnetic field which is generated by the skin in response to the primary magnetic field.

Fig. 1 schematically shows a dipole coil used in a conventional electrode device as an exciting coil. When the dipole coil 11 is supplied with a current, a primary magnetic field 10 is applied to a skin of interest.

However, the dipole coil 11 exhibits a wide distribution of the magnetic field 10, which means that the measurement result of the conventional electrode device must be influenced by the property of other tissues which are not intended to be measured and which are far away from the dipole coil. The other tissues can be other skins which are far away from the dipole coil and not intended to be measured. The other tissue can also be some interior tissue of a body and situated far away from the dipole coil.

SUMMARY OF THE INVENTION

An object of this invention is to provide an improved device for measuring electromagnetic signals of a tissue. The device for measuring electromagnetic signals of a tissue comprises at least two exciting coils for generating a primary magnetic field and applying it to the tissue, and adjacent exciting coils of each pair of exciting coils have opposite current flow, so that a distribution of the primary magnetic field is localized around the exciting coils. The device also comprises at least one receiving coil for receiving electromagnetic signals induced by a secondary magnetic field, and the secondary magnetic field is generated by the tissue in response to the primary magnetic field.

The advantage is that the measurement result is less influenced by other tissues which are far away from the exciting coils.

In an embodiment of the device, the exciting coils comprise 2ⁿ or 2n exciting coils, and n is an integer which is not less than 1.

The advantage is that the measurement result is more accurate.

According to another object, the invention also provides a method of measuring electromagnetic signals of a tissue, and a computer program used in the method of measuring electromagnetic signals of a tissue.

Detailed explanations and other aspects of the invention will be given below. DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present invention will become more apparent from the following detailed description considered in connection with the accompanying drawings, in which:

Fig.1 schematically shows a dipole coil used in a conventional electrode device;

Fig. 2 schematically shows a device for measuring electromagnetic signals of a tissue according to an embodiment of the invention.

Fig. 3 schematically shows a probe according to another embodiment of the device of Fig.

2;

Fig. 4 schematically shows two exciting coils according to an example of an arrangement of exciting coils;

Figs.5A-5G schematically show different examples of arrangements of exciting coils;

Fig. 6 is a flowchart illustrating a method of measuring electromagnetic signals of the tissue according to an embodiment of the invention.

The same reference numerals are used to denote similar parts throughout the Figures.

DETAILED DESCRIPTION Fig. 2 schematically shows a device for measuring electromagnetic signals of a tissue according to an embodiment of the invention.

The device 1 for measuring electromagnetic signals of a tissue (not shown in the Figures) comprises at least two exciting coils 21 for generating a primary magnetic field and applying it to the tissue and at least one receiving coil 22 for receiving electromagnetic signals induced by a secondary magnetic field. The secondary magnetic field is generated by the tissue in response to the primary magnetic field. Adjacent exciting coils 21 of each pair of exciting coils 21 have opposite current flow, so that a distribution of the primary magnetic field is localized around the exciting coils 21.

The exciting coils 21 are arranged symmetrically in a plane. Each exciting coil 21 can be dependent on the rest of the exciting coils 21, but each exciting coil 21 is arranged close to/to connect to one or more adjacent exciting coils 21. Alternatively, the exciting coils 21 can be wound from a metal thread, so that each exciting coil 21 can connect to one or more adjacent exciting coils 21. Each exciting coil 21 generates a primary magnetic field which counteracts another primary magnetic field generated by one or more adjacent exciting coils, so that the primary magnetic field far away from the exciting coils 21 is almost cancelled and the primary magnetic field close to the exciting coils 21 is strengthened.

During a measurement, the exciting coils 21 are placed close to the tissue to be measured and the primary magnetic field is localized around the exciting coils 21, namely, the primary magnetic field is localized around the tissue to be measured. The properties of other tissues which are far away from the exciting coils 21 will not impact the measurement result for the tissue to be measured.

The device 1 also comprises a processing unit 23 for processing the electromagnetic signals to acquire the conductivity of the tissue. The processing unit 23 can acquire the conductivity of the tissue by checking a Q-factor (Quality-factor) of the receiving coil 22. Optionally, the processing unit 23 can also acquire the conductivity of the tissue, based on a resonant peak influenced by the tissue. Optionally, the processing unit 23 can further acquire the conductivity of the tissue, based on the mutual induction of the exciting coils.

The processing unit 23 is also used for comparing the conductivity with a

pre-defined table to search the status of the tissue. The pre-defined table is stored in a database

(not shown in the Figures) of device 1 , and the pre-defined table comprises a set of conductivity ranges, and each conductivity range corresponds to a status. Each status may reflect a liquid content or tumor status of the tissue. The liquid can be water, and the tumor status can be normal or abnormal. The pre-defined table can be provided by a user or manufacturer of the device 1.

The tissue can be a skin or a tumor of a human or animal body. For example, the tissue is a skin of a body and the exciting coils 21 are placed close to the skin to be measured, the primary magnetic field being distributed over the skin (superficial layer of the skin). Only a very small primary magnetic field is distributed to the interior of the body or other skin parts far away from the exciting coils 21. Thus, the water content of the skin close to the exciting coils 21 can be measured with very little influence.

The device 1 further comprises an indicator 24 for indicating the conductivity of the tissue or the status of the tissue. The indicator 24 can be a display for displaying the status or conductivity of the tissue, a speaker for announcing the status or conductivity of the tissue, or a light for showing the status or conductivity of the tissue by means of a different color.

The exciting coils 21 and the receiving coil 22 can be arranged in a probe 25. The probe 25 is to be placed close to the tissue, so that the exciting coils 21 can generate the primary magnetic field and apply it to the tissue and the receiving coil 22 can receive the electromagnetic signals from the tissue. The probe 25 is connected to the processing unit 23 by a cable 26.

In Fig. 2, the probe 25 is a flexible band-shape for receiving the exciting coils 21 and the receiving coil 22 therein. Fig. 3 schematically shows a probe according to another embodiment of the device of Fig. 2. The probe 25 is a pen-shape for receiving the exciting coils 21 and receiving coil 22 at one end of it. The exciting coils 21 and the receiving coil 22 can be further embedded in a wrist. The probe 25 can be placed close to the tissue directly, e.g. placed close to a skin of a body, to detect the water content of the skin.

Alternatively, the exciting coils 21 and receiving coil 22 can be mounted on a tip or a catheter of an endoscope, so as to measure electromagnetic signals of a tissue in a body, e.g. a tumor in a body, to detect the statuses (abnormal or normal) of the tumor.

The exciting coils 21 may comprise 2ⁿ exciting coils, and n is an integer which is not less than 1. Fig. 4 schematically shows two exciting coils according to an example of an arrangement of exciting coils. The direction of a current in an exciting coil 21 is opposite to the direction of a current in another exciting coil 21, so that the distribution of the primary magnetic field is localized around the two exciting coils 21. Figs. 5A-5G schematically show different examples of an arrangement of exciting coils.

In Figs. 5A to 5G, "+" and "-" represent different magnetic field directions, respectively. Fig. 5A shows four (2 2 ) circular exciting coils symmetrically arranged in a row. Fig. 5B shows eight (23 ) circular exciting coils arranged in a row. Fig. 5C shows eight (2 ) circular exciting coils arranged in two rows. Fig. 5D shows sixteen (2 4 ) circular exciting coils. Fig. 5E shows four (22 ) rectangular exciting coils. Fig. 5F shows four (2 ) triangular exciting coils. Fig. 5G shows multiple circular exciting coils (2ⁿ) arranged symmetrically in a plane.

Alternatively, the exciting coils may comprise 2n exciting coils, and n is an integer which is not less than 1. Fig. 6 is a flowchart illustrating a method of measuring electromagnetic signals of a tissue according to an embodiment of the invention.

The method of measuring electromagnetic signals of a tissue comprises a step 61 and a step 62. The step 61 is to generate a primary magnetic field and apply it to the tissue by means of at least two exciting coils. Adjacent exciting coils 21 of each pair of exciting coils 21 have opposite current flow, so that the distribution of the primary magnetic field is localized around the exciting coils 21. The step 62 is to receive electromagnetic signals induced by a secondary magnetic field. The secondary magnetic field is generated by the tissue in response to the primary magnetic field.

The method also comprises a step 63 for processing the electromagnetic signals to acquire the conductivity of the tissue. The step 63 may be intended to acquire the conductivity of the tissue by checking a Q-factor (Quality-factor) of the receiving coil 22. Optionally, the step 63 may be also intended to acquire the conductivity of the tissue, based on a resonant peak influenced by the tissue. Optionally, the step 63 may be further intended to acquire the conductivity of the tissue, based on a mutual induction of the exciting coils.

The step 63 is also intended to compare the conductivity with a pre-defined table to search a status for the tissue. The pre-defined table is stored in a database (not shown in Fig. 1) of the device 1 , and the pre-defined table comprises a set of conductivity ranges and each conductivity range corresponds to a status. Each status may reflect a liquid content or tumor status of the tissue. The liquid can be water, and the tumor status can be normal or abnormal. The pre-defined table can be provided by a user or a manufacturer of the device 1.

A computer program is used in the method of measuring electromagnetic signals of a tissue. The method comprises a step 61 and a step 62. The step 61 is for generating a primary magnetic field and applying it to the tissue by at least two exciting coils 21. Adjacent exciting coils 21 of each pair of exciting coils 21 have opposite current flow, so that the distribution of the primary magnetic field is localized around the exciting coils 21. The step 62 is for receiving electromagnetic signals induced by a secondary magnetic field. The secondary magnetic field is generated by the tissue in response to the primary magnetic field.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim or in the description. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention can be implemented by units of hardware comprising several distinct elements and by units of a programmed computer. In the system claims enumerating several units, several of these units can be embodied by one and the same item of hardware or software. The usage of the words first, second and third, et cetera, does not indicate any ordering. These words are to be interpreted as names.

Claims

CLAIMS:

1. A device (1) for measuring electromagnetic signals of a tissue, comprising at least two exciting coils (21) for generating a primary magnetic field and applying it to the tissue, wherein adjacent exciting coils (21) of each pair of exciting coils (21) have opposite current flow, so that a distribution of the primary magnetic field is localized around the at least two exciting coils (21), and

at least one receiving coil (22) for receiving electromagnetic signals induced by a secondary magnetic field, wherein the secondary magnetic field is generated by the tissue in response to the primary magnetic field.

2. The device as claimed in claim 1, wherein the at least two exciting coils (21) comprise 2ⁿ or 2n exciting coils (21), and n is an integer which is not less than 1.

3. The device as claimed in claim 1, wherein the at least two exciting coils (21) are symmetrically arranged in a plane, and placed close to the tissue during measuring the electromagnetic signals of the tissue.

4. The device as claimed in claim 1, wherein each exciting coil (21) is dependent on the rest of the exciting coils (21), and each exciting coil (21) is arranged close to/to connect to one or more adjacent exciting coils (21).

5. The device as claimed in claim 1, wherein the exciting coils (21) are wound from one metal thread, so that each exciting coil (21) is connected with one or more adjacent exciting coils (21).

6. The device as claimed in claim 1, further comprising a processing unit (23) for processing the electromagnetic signals to acquire the conductivity of the tissue.

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7. The device as claimed in claim 6, wherein the processing unit (23) is further used for comparing the conductivity with a pre-defined table to search a status for the tissue, and the pre-defined table is stored in the device (1) and the pre-defined table comprises a set of conductivity ranges and each conductivity range corresponds to a status.

8. The device as claimed in claim 7, wherein the status reflects a liquid content of the tissue or a tumor status of the tissue.

9. The device as claimed in claim 7, further comprising an indicator (24) for indicating the conductivity of the tissue or the status of the tissue.

10. The device as claimed in claim 1, wherein the exciting coils (21) and the receiving coil (22) are arranged in a probe (25), a catheter of an endoscope, or a tip of an endoscope.

11. A method of measuring electromagnetic signals of a tissue comprising the steps of:

generating (61) a primary magnetic field and applying it to the tissue by at least two exciting coils, wherein adjacent exciting coils of each pair of exciting coils have opposite current flow, so that the distribution of the primary magnetic field is localized around the at least two exciting coils, and

receiving (62) electromagnetic signals induced by a secondary magnetic field, wherein the secondary magnetic field is generated by the tissue in response to the primary magnetic field.

12. The method as claimed in claim 11, further comprising a step (63) of processing the electromagnetic signals to acquire the conductivity of the tissue.

13. The method as claimed in claim 12, wherein the processing step (63) is further intended to compare the conductivity with a pre-defined table to search a status for

2 the tissue, and the pre-defined table is stored in the device (1) and comprises a set of conductivity ranges and each conductivity range corresponds to a status.

14. The method as claimed in claim 13, further comprising a step (64) of indicating the conductivity of the tissue or the status of the tissue.

15. A computer program used in a method of measuring electromagnetic signals of a tissue, the method comprising the steps of:

generating (61) a primary magnetic field and applying it to the tissue by at least two exciting coils (21), wherein adjacent exciting coils (21) of each pair of exciting coils (21) have opposite current flow, so that the distribution of the primary magnetic field is localized around the exciting coils (21), and

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