Magnetic resonance imaging interference immune device

• US 20040263174A1
• Filed: 07/08/2004
• Published: 12/30/2004
• Est. Priority Date: 06/24/2003
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Biophan Technologies Incorporated
• Inventors: Gray, Robert W., MacDonald, Stuart G.
• Granted Patent: US 7,729,777 B2
• Time in Patent Office: Days
• US Class Current: 324/322
• CPC Class Codes: A61B 2562/222 Electrical cables or leads therefor, e.g. coaxial cables or ribbon cables
• CPC Class Codes: A61N 1/05 for implantation or insertion into the body, e.g. heart electrode A61N1/06 takes precedence
• CPC Class Codes: A61N 1/086 Magnetic resonance imaging [MRI] compatible leads
• CPC Class Codes: A61N 1/37 Monitoring; Protecting
• CPC Class Codes: A61N 1/3718 Monitoring of or protection against external electromagnetic fields or currents
• CPC Class Codes: G01R 33/285 Invasive instruments, e.g. catheters or biopsy needles, specially adapted for tracking, guiding or visualization by NMR
• CPC Class Codes: G01R 33/288 Provisions within MR facilities for enhancing safety during MR, e.g. reduction of the specific absorption rate [SAR], detection of ferromagnetic objects in the scanner room
• CPC Class Codes: G01R 33/34084 implantable coils or coils being geometrically adaptable to the sample, e.g. flexible coils or coils comprising mutually movable parts
• CPC Class Codes: H03H 7/42 Networks for transforming balanced signals into unbalanced signals and vice versa, e.g. baluns

Abstract

A voltage compensation unit reduces the effects of induced voltages upon a device having a single wire line. The single wire line has balanced characteristic impedance. The voltage compensation unit includes a tunable compensation circuit connected to the wire line. The tunable compensation circuit applies supplemental impedance to the wire line. The supplemental impedance causes the characteristic impedance of the wire line to become unbalanced, thereby reducing the effects of induced voltages caused by changing magnetic fields.

Claims

1. An electrical lead component for a medical device which reduces the effects of MRI induced signals, comprising:

a medical device electrical lead capable of providing an electrical path to a desired tissue region; and

a coil that generates a voltage due to a changing MRI electromagnetic field opposite to that which would be induced by the changing MRI electromagnetic field in said medical device electrical lead so as to reduce voltages induced by the changing MRI electromagnetic field.

2. The electrical lead component as claimed in claim 1, wherein said coil is curved in three different spatial directions.

3. The electrical lead component as claimed in claim 1, further comprising:

orientation means for changing a spatial orientation of said coil to modify the strength of the voltage induced by the changing MRI electromagnetic field.

4. The electrical lead component as claimed in claim 1, wherein the changing MRI electromagnetic field is a MRI switched gradient field.

5. The electrical lead component as claimed in claim 1, wherein the changing MRI electromagnetic field is a MRI radio-frequency field.

6. An electrical lead component for a medical device which reduces the effects of MRI induced signals, comprising:

a medical device electrical lead capable of providing an electrical path to a desired tissue region; and

a plurality of coils, each coil generating a voltage due to a changing MRI electromagnetic field such that a combination of voltages due to a changing MRI electromagnetic field provides a combined voltage that is opposite to the voltage which would be induced by the changing MRI electromagnetic field in said medical device electrical lead so as to reduce voltages induced by the changing MRI electromagnetic field.

7. The electrical lead component as claimed in claim 6, wherein said coils are curved in three different spatial directions.

8. The electrical lead component as claimed in claim 6, further comprising:

orientation means for changing a spatial orientation of said coils to modify the strength of the voltage due to the changing MRI electromagnetic field.

9. The electrical lead component as claimed in claim 6, wherein the changing MRI electromagnetic field is a MRI switched gradient field.

10. The electrical lead component as claimed in claim 6, wherein the changing MRI electromagnetic field is a MRI radio-frequency field.

11. An electrical lead component for a medical device which reduces the effects of MRI induced signals, comprising:

a medical device electrical lead capable of providing an electrical path to a desired tissue region; and

three orthogonally planar coils, each coil generating a voltage due to a changing MRI electromagnetic field such that a combination of voltages due to a changing MRI electromagnetic field provides a combined voltage that is opposite to the voltage which would be induced by the changing MRI electromagnetic field in said medical device electrical lead so as to reduce voltages induced by the changing MRI electromagnetic field.

12. The electrical lead component as claimed in claim 11, wherein the changing MRI electromagnetic field is a MRI switched gradient field.

13. The electrical lead component as claimed in claim 11, wherein the changing MRI electromagnetic field is a MRI switched gradient field.

14. An electrical lead component for a medical device which reduces the effects of MRI induced signals, comprising:

a medical device electrical lead capable of providing an electrical path to a desired tissue region;

a plurality of coils, each coil generating a voltage due to a changing MRI electromagnetic field;

a sensor to measure a strength of voltages induced by the changing MRI electromagnetic field; and

a switching device, operatively connected to said sensor and plurality of coils, to operatively connect a number of said plurality of coils in response to the measured strength of voltages induced by the changing MRI electromagnetic field such that a combination of voltages due to a changing MRI electromagnetic field provides a combined voltage that is opposite to the voltage which would be induced by the changing MRI electromagnetic field in said medical device electrical lead so as to reduce voltages induced by the changing MRI electromagnetic field.

15. The electrical lead component as claimed in claim 14, wherein said coils are curved in three different spatial directions.

16. The electrical lead component as claimed in claim 14, further comprising:

orientation means for changing a spatial orientation of said coils to modify the strength of the voltage induced by the changing MRI electromagnetic field.

17. The electrical lead component as claimed in claim 14, wherein the changing MRI electromagnetic field is a MRI switched gradient field.

18. The electrical lead component as claimed in claim 14, wherein the changing MRI electromagnetic field is a MRI switched gradient field.

19. An electrical lead component for a medical device which reduces the effects of MRI induced signals, comprising:

a medical device electrical lead capable of providing an electrical path to a desired tissue region;

three orthogonally planar coils, each coil generating a voltage due to a changing MRI electromagnetic field;

a sensor to measure a strength of voltages induced by the changing MRI electromagnetic field; and

a switching device, operatively connected to said sensor and said coils, to operatively connect a number of said coils in response to the measured strength of voltages induced by the changing MRI electromagnetic field such that a combination of voltages due to a changing MRI electromagnetic field provides a combined voltage that is opposite to the voltage which would be induced by the changing MRI electromagnetic field in said medical device electrical lead so as to reduce voltages induced by the changing MRI electromagnetic field.

20. The electrical lead component as claimed in claim 19, wherein the changing MRI electromagnetic field is a MRI switched gradient field.

21. The electrical lead component as claimed in claim 19, wherein the changing MRI electromagnetic field is a MRI radio-frequency field.

22. An electrical lead component for a medical device which reduces the effects of MRI induced signals, comprising:

a medical device electrical lead capable of providing an electrical path to a desired tissue region;

a plurality of coils, each coil generating a voltage due to a changing MRI electromagnetic field;

a transceiver to receive a signal indicating a number of coils to be connected; and

a switching device, operatively connected to said transceiver and plurality of coils, to operatively connect a number of said plurality of coils in response to the received signal indicating the number of coils to be connected such that a combination of voltages due to a changing MRI electromagnetic field provides a combined voltage that is opposite to the voltage which would be induced by the changing MRI electromagnetic field in said medical device electrical lead so as to reduce voltages induced by the changing MRI electromagnetic field.

23. The electrical lead component as claimed in claim 22, wherein said coils are curved in three different spatial directions.

24. The electrical lead component as claimed in claim 22, further comprising:

orientation means for changing a spatial orientation of said coils to modify the strength of the voltage induced by the changing MRI electromagnetic field.

25. The electrical lead component as claimed in claim 22, wherein the changing MRI electromagnetic field is a MRI switched gradient field.

26. The electrical lead component as claimed in claim 22, wherein the changing MRI electromagnetic field is a MRI radio-frequency field.

27. An electrical lead component for a medical device which reduces the effects of MRI induced signals, comprising:

a medical device electrical lead capable of providing an electrical path to a desired tissue region;

three orthogonally planar coils, each coil generating a voltage due to a changing MRI electromagnetic field;

a transceiver to receive a signal indicating a number of coils to be connected; and

a switching device, operatively connected to said transceiver and said coils, to operatively connect a number of said coils in response to the received signal indicating the number of coils to be connected such that a combination of voltages due to a changing MRI electromagnetic field provides a combined voltage that is opposite to the voltage which would be induced by the changing MRI electromagnetic field in said medical device electrical lead so as to reduce voltages induced by the changing MRI electromagnetic field.

28. The electrical lead component as claimed in claim 27, wherein the changing MRI electromagnetic field is a MRI switched gradient field.

29. The electrical lead component as claimed in claim 27, wherein the changing MRI electromagnetic field is a MRI radio-frequency field.

30. A medical device which reduces the effects of MRI induced signals, comprising:

a medical device capable of providing medical treatment to a desired tissue region; and

a coil that generates a voltage induced by a changing MRI electromagnetic field opposite to a voltage which would be induced by the changing MRI electromagnetic field in said medical device so as to reduce voltages induced by the changing MRI electromagnetic field.

31. The medical device as claimed in claim 30, wherein said coil is curved in three different spatial directions.

32. The medical device as claimed in claim 30, further comprising:

orientation means for changing a spatial orientation of said coil to modify the strength of the voltage induced by the changing MRI electromagnetic field.

33. The medical device as claimed in claim 30, wherein the changing MRI electromagnetic field is a MRI switched gradient field.

34. The medical device as claimed in claim 30, wherein the changing MRI electromagnetic field is a MRI radio-frequency field.

35. A medical device which reduces the effects of MRI induced signals, comprising:

a medical device capable of providing medical treatment to a desired tissue region; and

a plurality of coils, each coil generating a voltage due to a changing MRI electromagnetic field such that a combination of voltages due to a changing MRI electromagnetic field provides a combined voltage that is opposite to the voltage which would be induced by the changing MRI electromagnetic field in said medical device so as to reduce voltages induced by the changing MRI electromagnetic field.

36. The medical device as claimed in claim 35, wherein said coils are curved in three different spatial directions.

37. The medical device as claimed in claim 35, further comprising:

orientation means for changing a spatial orientation of said coil to modify the strength of the voltage induced by the changing MRI electromagnetic field.

38. The medical device as claimed in claim 35, wherein the changing MRI electromagnetic field is a MRI switched gradient field.

39. The medical device as claimed in claim 35, wherein the changing MRI electromagnetic field is a MRI radio-frequency field.

40. A medical device which reduces the effects of MRI induced signals, comprising:

a medical device capable of providing medical treatment to a desired tissue region; and

three orthogonally planar coils, each coil generating a voltage due to a changing MRI electromagnetic field such that a combination of voltages due to a changing MRI electromagnetic field provides a combined voltage that is opposite to the voltage which would be induced by the changing MRI electromagnetic field in said medical device so as to reduce voltages induced by the changing MRI electromagnetic field.

41. The medical device as claimed in claim 40, wherein the changing MRI electromagnetic field is a MRI switched gradient field.

42. The medical device as claimed in claim 40, wherein the changing MRI electromagnetic field is a MRI radio-frequency field.

43. A medical device which reduces the effects of MRI induced signals, comprising:

a medical device capable of providing medical treatment to a desired tissue region,

a plurality of coils, each coil generating a voltage due to a changing MRI electromagnetic field;

a sensor to measure a strength of voltages induced by the changing MRI electromagnetic field; and

a switching device, operatively connected to said sensor and plurality of coils, to operatively connect a number of said plurality of coils in response to the measured strength of voltages induced by the changing MRI electromagnetic field such that a combination of voltages due to a changing MRI electromagnetic field provides a combined voltage that is opposite to the voltage which would be induced by the changing MRI electromagnetic field in said medical device so as to reduce voltages induced by the changing MRI electromagnetic field.

44. The medical device as claimed in claim 43, wherein the changing MRI electromagnetic field is a MRI switched gradient field.

45. The medical device as claimed in claim 43, wherein the changing MRI electromagnetic field is a MRI radio-frequency field.

46. The medical device as claimed in claim 43, wherein said coils are curved in three different spatial directions.

47. The medical device as claimed in claim 43, further comprising:

orientation means for changing a spatial orientation of said coil to modify the strength of the voltage induced by the changing MRI electromagnetic field.

48. A medical device which reduces the effects of MRI induced signals, comprising:

a medical device capable of providing medical treatment to a desired tissue region;

three orthogonally planar coil, each coil generating a voltage due to a changing MRI electromagnetic field;

a sensor to measure a strength of voltages induced by the changing MRI electromagnetic field; and

a switching device, operatively connected to said sensor and plurality of coils, to operatively connect a number of said plurality of coils in response to the measured strength of voltages induced by changing MRI electromagnetic field such that a combination of voltages due to a changing MRI electromagnetic field provides a combined voltage that is opposite to the voltage which would be induced by the changing MRI electromagnetic field in said medical device so as to reduce voltages induced by the changing MRI electromagnetic field.

49. The medical device as claimed in claim 48, wherein the changing MRI electromagnetic field is a MRI switched gradient field.

50. The medical device as claimed in claim 48, wherein the changing MRI electromagnetic field is a MRI radio-frequency field.

51. A medical device which reduces the effects of MRI induced signals, comprising:

a medical device capable of providing medical treatment to a desired tissue region;

a plurality of coils, each coil generating a voltage due to a changing MRI electromagnetic field;

a transceiver to receive a signal indicating a number of coils to be connected; and

a switching device, operatively connected to said transceiver and said coils, to operatively connect a number of said coils in response to the received signal indicating the number of coils to be connected such that a combination of voltages due to a changing MRI electromagnetic field provides a combined voltage that is opposite to the voltage which would be induced by the changing MRI electromagnetic field in said medical device so as to reduce voltages induced by the changing MRI electromagnetic field.

52. The medical device as claimed in claim 51, wherein the changing MRI electromagnetic field is a MRI switched gradient field.

53. The medical device as claimed in claim 51, wherein the changing MRI electromagnetic field is a MRI radio-frequency field.

54. The medical device as claimed in claim 51, wherein said coils are curved in three different spatial directions.

55. The medical device as claimed in claim 51, further comprising:

orientation means for changing a spatial orientation of said coil to modify the strength of the voltage induced by the changing MRI electromagnetic field.

56. A medical device which reduces the effects of MRI induced signals, comprising:

a medical device capable of providing medical treatment to a desired tissue region;

three orthogonally planar coil, each coil generating a voltage due to a changing MRI electromagnetic field;

a transceiver to receive a signal indicating a number of coils to be connected; and

a switching device, operatively connected to said transceiver and said coils, to operatively connect a number of said coils in response to the received signal indicating the number of coils to be connected such that a combination of voltages due to a changing MRI electromagnetic field provides a combined voltage that is opposite to the voltage which would be induced by the changing MRI electromagnetic field in said medical device so as to reduce voltages induced by the changing MRI electromagnetic field.

57. The medical device as claimed in claim 56, wherein the changing MRI electromagnetic field is a MRI switched gradient field.

58. The medical device as claimed in claim 56, wherein the changing MRI electromagnetic field is a MRI radio-frequency field.

59. An electrical lead component for a medical device which reduces the effects of MRI induced signals, comprising:

a medical device electrical lead capable of providing an electrical path to a desired tissue region;

a voltage source;

a sensor to sense voltages induced by the changing MRI electromagnetic field; and

a switching device, operatively connected to said sensor and voltage source, to operatively connect said voltage source to said medical device electrical lead in response to the sensed voltage induced by the changing MRI electromagnetic field such that said voltage source provides a voltage that is opposite to the voltage which would be induced by the changing MRI electromagnetic field in said medical device electrical lead so as to reduce voltages induced by the changing MRI electromagnetic field.

60. The electrical lead component as claimed in claim 59, wherein said voltage source is a battery.

61. The electrical lead component as claimed in claim 59, wherein said voltage source is a capacitor.

62. The electrical lead component as claimed in claim 59, further comprising a variable resistor connected to said voltage source to regulate an amount of voltage being provided.

63. The electrical lead component as claimed in claim 59, wherein the changing MRI electromagnetic field is a MRI switched gradient field.

64. The electrical lead component as claimed in claim 59, wherein the changing MRI electromagnetic field is a MRI radio-frequency field.

65. A medical device which reduces the effects of MRI induced signals, comprising:

a medical device capable of providing medical treatment to a desired tissue region;

a voltage source;

a sensor to sense voltages induced by the changing MRI electromagnetic field; and

a switching device, operatively connected to said sensor and voltage source, to operatively connect said voltage source to said medical device in response to the sensed voltage induced by the changing MRI electromagnetic field such that said voltage source provides a voltage that is opposite to the voltage which would be induced by the changing M/RI electromagnetic field in said medical device so as to reduce voltages induced by the changing MRI electromagnetic field.

66. The medical device as claimed in claim 65, wherein the changing MRI electromagnetic field is a MRI switched gradient field.

67. The medical device as claimed in claim 65, wherein the changing MRI electromagnetic field is a MRI radio-frequency field.

68. The medical device as claimed in claim 65, wherein said voltage source is a battery.

69. The medical device as claimed in claim 65, wherein said voltage source is a capacitor.

70. The medical device as claimed in claim 65, further comprising a variable resistor connected to said voltage source to regulate an amount of voltage being provided.