Ultrasound-hall effect imaging system and method

• US 6,520,911 B1
• Filed: 05/11/1999
• Issued: 02/18/2003
• Est. Priority Date: 07/03/1996
• Status: Expired due to Term

• Current Assignee: The United States of America As Represented By The Secretary of Agriculture
• Original Assignee: United States Department Of Health And Human Services
• Inventors: Wen, Han
• Primary Examiner(s): MANUEL, GEORGE C
• Application Number:
  US09/202,459
• Time in Patent Office: 1,379 Days
• Field of Search: 175/40, 175/50, 181/106, 731/05, 600/437, 600/438, 600/442, 600/407, 600/443, 600/587, 324/226, 324/228, 324/260
• US Class Current: 600/437
• CPC Class Codes: A61B 5/0093 Detecting, measuring or recording by applying one single type of energy and measuring its conversion into another type of energy
• CPC Class Codes: G01V 3/082 operating with fields produced by spontaneous potentials, e.g. electrochemical or produced by telluric currents G01V3/26 takes precedence

Abstract

A system and method of imaging based on the interaction of ultrasonic pulses with a magnetic field. A static magnetic field is applied to an object having conductive properties. An ultrasound pulse is propagated into the object, and an electrical signal is detected which is related to the interaction of the ultrasound pulse local displacement of the conductive object and the magnetic field. Alternatively, and equivalently, an electrical pulse is propagated into the object, and an ultrasound signal is detected which is related to the interaction of the electrical pulse generated in the conductive object and the magnetic field. The acquired acoustic signals or the acquired electrical signals are processed to provide an image of the object. The acquired signals are dependent on local conductivity as well as local acoustic properties.

Claims

1. A method for acquiring information on the conductivity distribution in an object, said method comprising the steps of:

applying a magnetic field to said object;

applying an excitation signal along a direction non-parallel to said magnetic field and which induces a local charge displacement in said object as said excitation signal propagates in said object, said local charge displacement capable of being induced in the bulk of said object; and

acquiring a signal encoded with information indicative of local conductivity of said object for regions along path traversed by said excitation signal, said signal related to an interaction between said magnetic field and said local charge displacement as said excitation signal propagates in said object, said regions capable of being located in the bulk of said object.

2. The method according to claim 1, further comprising the step of generating an image from said signal, said image weighted by a function of conductivity of said object, said image thereby representing the conductivity distribution of said object.

3. The method according to claim 2, wherein said image is weighted by conductivity gradient magnitude.

4. The method according to claim 2, wherein said image is weighted by conductivity gradient magnitude and polarity.

5. The method according to claim 2, wherein said image is weighted by conductivity magnitude.

6. The method according to claim 1, wherein said excitation signal is an acoustic signal which propagates through said object, and said signal is an electrical signal corresponding to a Lorentz interaction between said magnetic field and local displacement of said object as said acoustic signal propagates through said object.

7. The method according to claim 6, wherein said acoustic signal is localized along a direction of propagation into said object, and wherein multiple acoustic signals are directed along respective propagation directions into said object, thereby spatially scanning said object with the multiple acoustic signals.

8. The method according to claim 6, wherein said electrical signal is acquired by at least one coil inductively coupled to the object.

9. The method according to claim 6, wherein said electrical signal is acquired by at least one electrode directly coupled to said object.

10. The method according to claim 1, wherein said excitation signal is an electrical signal, and said signal is an acoustic signal corresponding to a Lorentz interaction between said magnetic field and local electrical current in said object as said electrical signal propagates through said object.

11. The method according to claim 10, wherein said acoustic signal is detected along a given direction, and wherein said given direction is scanned.

12. The method according to claim 10, wherein said acoustic signal is detected with a transducer which includes an array of elements that concurrently detect acoustic energy respectively localized along respective directions.

13. The method according to claim 1, wherein said object is at least a portion of a human body.

14. A system for acquiring information on the conductivity distribution in an object, said system comprising:

a magnet which applies a magnetic field to said object;

means for generating an excitation signal applied along a direction non-parallel to said magnetic field and which induces a local charge displacement in said object as said excitation signal propagates in said object, said local charge displacement capable of being induced in the bulk of said object; and

means for acquiring a signal encoded with information indicative of local conductivity of said object for regions along path traversed by said excitation signal, said signal related to a Lorentz interaction between said magnetic field and said local charge displacement as said excitation signal propagates in said object, said regions capable of being located in the bulk of said object.

15. The system according to claim 14, further comprising means for generating an image from said signal, said image weighted by a function of conductivity of said object, said image thereby representing the conductivity distribution of said object.

16. The system according to claim 14, wherein said excitation signal is an acoustic signal which propagates through said object, and said signal is an electrical signal corresponding to a Lorentz interaction between said magnetic field and local displacement of said object as said acoustic signal propagates through said object.

17. The system according to claim 14, wherein said excitation signal is an electrical signal, and said signal is an acoustic signal corresponding to a Lorentz interaction between said magnetic field and local electrical current in said object as said electrical signal propagates through said object.

18. An apparatus for acquiring information on the conductivity distribution in an object, comprising:

an acoustic transducer coupled to said object and which generates an incident acoustic signal that propagates into the bulk of said object;

a magnetic element that generates a magnetic field in said object;

an electrical signal receiver that receives an electrical signal related to an interaction between said acoustic signal and said magnetic field as said acoustic signal propagates through the bulk of said object.

19. The apparatus according to claim 18, further comprising a processor that generates an image of said object based on said electrical signal.

20. The apparatus according to claim 18, wherein said electrical signal receiver includes at least one coil inductively coupled to the object.

21. The apparatus according to claim 18, wherein said electrical signal receiver includes at least one electrode directly coupled to said object.

22. The apparatus according to claim 18, wherein said acoustic transducer generates said acoustic signal as a beam localized along a direction of propagation into said object, and wherein said acoustic transducer generates a series of acoustic signals each directed along a respective propagation direction into said object, thereby spatially scanning said object with the series of acoustic signals.

23. An apparatus for acquiring information on the conductivity distribution in an object, comprising:

a magnetic element that generates a magnetic field in said object;

an electrical signal source that generates a time-varying electrical signal which is applied along a direction non-parallel to said magnetic field and which propagates through the bulk of said object; and

an acoustic transducer coupled to said object and which detects an acoustic signal that propagates through the bulk of said object and relates to an interaction between said time-varying electrical signal and said magnetic field.

24. The apparatus according to claim 23, wherein said acoustic transducer detects acoustic energy localized along a given direction, and wherein said given direction is scanned.

25. The apparatus according to claim 23, wherein said acoustic transducer includes an array of elements that concurrently detect acoustic energy from the object.

26. A method for imaging the conductivity distribution in an object, said method comprising the steps of:

applying an electrical excitation signal and a magnetic field to said object, the electrical excitation signal being along a direction non-parallel to said magnetic field, to induce a local charge displacement in said object as said excitation signal propagates in said object;

acquiring an acoustic signal using a transducer that includes an array of elements that concurrently detect said acoustic signal, said acoustic signal encoded with information indicative of local conductivity of said object for regions along path traversed by said excitation signal, said acoustic signal corresponding to a Lorentz interaction between said magnetic field and said local charge displacement as said excitation signal propagates in said object; and

generating an image from said acoustic signal, said image weighted by a function of conductivity of said object, said image thereby representing the conductivity distribution of said object.

27. A method for imaging an object, comprising the steps of:

applying an electrical excitation to said object in the presence of a magnetic field to cause Hall effect induction of an ultrasonic signal distributed in the bulk of said object;

acquiring the induced distributed ultrasonic signal using an array of ultrasound transducer elements that concurrently detect the induced distributed ultrasonic signal; and

processing the acquired induced distributed ultrasound signal concurrently detected by the array of ultrasound transducer elements to reconstruct an image.

28. A method for acquiring information on the conductivity distribution in an object, said method comprising the steps of:

applying a magnetic field to said object;

applying an excitation signal along a direction non-parallel to said magnetic field and which induces a local charge displacement in said object as said excitation signal propagates in said object;

acquiring a signal encoded with information indicative of local conductivity of said object for regions along path traversed by said excitation signal, said signal related to an interaction between said magnetic field and said local charge displacement as said excitation signal propagates in said object; and

generating an image from said signal, said image weighted by a function of conductivity of said object, said image thereby representing the conductivity distribution of said object.

29. A method for acquiring information on the conductivity distribution in an object, said method comprising the steps of:

applying a magnetic field to said object;

applying an excitation signal along a direction non-parallel to said magnetic field and which induces a local charge displacement in said object as said excitation signal propagates in said object;

acquiring a signal encoded with information indicative of local conductivity of said object for regions along path traversed by said excitation signal, said signal related to an interaction between said magnetic field and said local charge displacement as said excitation signal propagates in said object; and

wherein said excitation signal is an acoustic signal localized along a direction of propagation into said object, and said signal is an electrical signal corresponding to a Lorentz interaction between said magnetic field and local displacement of said object as said acoustic signal propagates through said object; and

wherein multiple acoustic signals are directed along respective propagation directions into said object, thereby spatially scanning said object with multiple acoustic signals.

30. A method for acquiring information on the conductivity distribution in an object, said method comprising the steps of:

applying a magnetic field to said object;

applying an excitation signal along a direction non-parallel to said magnetic field and which induces a local charge displacement in said object as said excitation signal propagates in said object;

acquiring a signal encoded with information indicative of local conductivity of said object for regions along path traversed by said excitation signal, said signal related to an interaction between said magnetic field and said local charge displacement as said excitation signal propagates in said object;

wherein said excitation signal is a time-varying electrical signal, and said signal is an acoustic signal corresponding to a Lorentz interaction between said magnetic field and local electrical current in said object as said time-varying electrical signal propagates through said object; and

wherein said acoustic signal is detected along a given direction, and wherein said given direction is scanned.

31. A method for acquiring information on the conductivity distribution in an object, said method comprising the steps of:

applying a magnetic field to said object;

applying an excitation signal along a direction non-parallel to said magnetic field and which induces a local charge displacement in said object as said excitation signal propagates in said object;

acquiring a signal encoded with information indicative of local conductivity of said object for regions along path traversed by said excitation signal, said signal related to an interaction between said magnetic field and said local charge displacement as said excitation signal propagates in said object;

wherein said excitation signal is a time-varying electrical signal, and said signal is an acoustic signal corresponding to a Lorentz interaction between said magnetic field and local electrical current in said object as said time-varying electrical signal propagates through said object; and

wherein said acoustic signal is detected with a transducer which includes an array of elements that concurrently detect acoustic energy respectively localized along respective directions.

32. A system for acquiring information on the conductivity distribution in an object, said system comprising:

a magnet which applies a magnetic field to said object;

means for generating an excitation signal applied along a direction non-parallel to said magnetic field and which induces a local charge displacement in said object as said excitation signal propagates in said object; and

means for acquiring a signal encoded with information indicative of local conductivity of said object for regions along path traversed by said excitation signal, said signal related to a Lorentz interaction between said magnetic field and said local charge displacement as said excitation signal propagates in said object; and

means for generating an image from said signal, said image weighted by a function of conductivity of said object, said image thereby representing the conductivity distribution of said object.

33. An apparatus for acquiring information on the conductivity distribution in an object, comprising:

an acoustic transducer coupled to said object and which generates an incident acoustic signal that propagates into said object;

a magnetic element that generates a magnetic field in said object;

an electrical signal receiver that receives an electrical signal related to an interaction between said acoustic signal and said magnetic field as said acoustic signal propagates through said object; and

a processor that generates an image of said object based on said electrical signal.

34. An apparatus for acquiring information on the conductivity distribution in an object, comprising:

an acoustic transducer coupled to said object and which generates an incident acoustic signal that propagates into said object;

a magnetic element that generates a magnetic field in said object;

an electrical signal receiver that receives an electrical signal related to an interaction between said acoustic signal and said magnetic field as said acoustic signal propagates through said object; and

wherein said acoustic transducer generates said acoustic signal as a beam localized along a direction of propagation into said object, and wherein said acoustic transducer generates a series of acoustic signals each directed along a respective propagation direction into said object, thereby spatially scanning said object with the series of acoustic signals.

35. An apparatus for acquiring information on the conductivity distribution in an object, comprising:

a magnetic element that generates a magnetic field in said object;

an electrical signal source that generates a time-varying electrical signal which is applied along a direction non-parallel to said magnetic field and which propagates through said object;

an acoustic transducer coupled to said object and which detects an acoustic signal that propagates through said object and relates to an interaction between said time-varying electrical signal and said magnetic field; and

wherein said acoustic transducer detects acoustic energy localized along a given direction, and wherein said given direction is scanned.

36. An apparatus for acquiring information on the conductivity distribution in an object, comprising:

a magnetic element that generates a magnetic field in said object;

an electrical signal source that generates a time-varying electrical signal which is applied along a direction non-parallel to said magnetic field and which propagates through said object;

an acoustic transducer coupled to said object and which detects an acoustic signal that propagates through said object and relates to an interaction between said time-varying electrical signal and said magnetic field; and

wherein said acoustic transducer includes an array of elements that concurrently detect acoustic energy from the object.

37. A method for acquiring information applicable for imaging an object based on a spatial function of the conductivity constant and the dielectric constant in the object, said method comprising the steps of:

applying a magnetic field to said object, said object including dielectric properties;

applying an excitation signal along a direction non-parallel to said magnetic field and which induces a local charge displacement in said object as said excitation signal propagates in said object; and

acquiring a signal encoded with information that is a spatial function of the local conductivity constant and the local dielectric constant of said object for a plurality of regions along a path traversed by said excitation signal, said signal related to an interaction between said magnetic field and said local charge displacement along the path as said excitation signal propagates in said object.

38. The method according to claim 37, wherein said local charge displacement is capable of being induced in the bulk of said object, and said plurality of regions are capable of being in the bulk of said object.

39. The method according to claim 37, wherein said object is at least a portion of a human body.