Magnetic resonance imaging interference immune device

• US 7,123,013 B2
• Filed: 07/08/2004
• Issued: 10/17/2006
• Est. Priority Date: 06/24/2003
• Status: Expired due to Fees

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Biophan Technologies Incorporated
• Inventors: Gray, Robert W.
• Primary Examiner(s): Shrivastav, Brij B.
• Application Number:
  US10/886,743
• Publication Number:
  US 20040263173A1
• Time in Patent Office: 831 Days
• Field of Search: 324/318, 324/319, 324/322, 324/309, 324/307, 600/423, 600/485, 600/410, 607/122, 607/117
• US Class Current: 324/318
• 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. A lead for medical applications that reduces the effects of MRI induced signals, comprising:

two coiled conductive strands forming a spring-like configuration such that current flows over a surface thereof, through contact points between adjacent loops of the coiled conductive strands;

a first insulating coating formed over a first portion of said two coiled conductive strands such that a first inline inductive element having a first inductance is formed, the current flowing along a curvature of said two coiled conductive strands in the first insulating coated portion of two coiled conductive strands; and

a second insulating coating formed over a second portion of said two coiled conductive strands such that a second inline inductive element having a second inductance is formed, the current flowing along a curvature of said two coiled conductive strands in the second insulating coated portion of two coiled conductive strands;

said first inductance being different from said second inductance.

2. The lead as claimed in claim 1, further comprising:

a ferrite material positioned in said first portion of said two coiled conductive strands having said first insulating coating formed thereon.

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

a ferrite material positioned in said second portion of said two coiled conductive strands having said second insulating coating formed thereon.

4. The lead as claimed in claim 1, further comprising:

ferrite material positioned in said first and second portions of said two coiled conductive strands having said first and second insulating coatings formed thereon.

18. The lead as claimed in claim 1, further comprising:

a ferrite material positioned in said portion of said two coiled conductive strands having said insulating coating formed thereon.

19. The lead as claimed in claim 1, wherein an inductance of the formed inline inductive element being adjusted by adjusting a length of a region to which said insulating coating is formed over the portion of said two coiled conductive strands.

5. A lead for medical applications that reduces the effects of MRI induced signals, comprising:

two coiled conductive strands forming a spring-like configuration such that current flows over a surface thereof, through contact points between adjacent loops of the coiled conductive strands;

a first adjustable resistive material formed over a first portion of said two coiled conductive strands such that a first inline inductive element having a first inductance is formed, the current flowing along a curvature of said two coiled conductive strands in the first adjustable resistive material portion of said two coiled conductive strands;

a second adjustable resistive material formed over a second portion of said two coiled conductive strands such that a second inline inductive element having a second inductance is formed, the current flowing along a curvature of said two coiled conductive strands in the second adjustable resistive material portion of said two coiled conductive strands;

said first inductance being different from said second inductance.

6. The lead as claimed in claim 5, further comprising:

a ferrite material positioned in said first portion of said two coiled conductive strands having said first adjustable resistive material formed thereon.

7. The lead as claimed in claim 5, further comprising:

a ferrite material positioned in said second portion of said two coiled conductive strands having said second adjustable resistive material formed thereon.

8. The lead as claimed in claim 5, further comprising:

ferrite material positioned in said first and second portions of said two coiled conductive strands having said first and second adjustable resistive material formed thereon.

9. A lead for medical applications that reduces the effects of MRI induced signals, comprising:

a coiled conductive strand forming a spring-like configuration such that current flows over a surface thereof, through contact points between adjacent loops of the coiled conductive strand;

a first insulating coating formed over a first portion of said coiled conductive strand such that a first inline inductive element having a first inductance is formed, the current flowing along a curvature of said coiled conductive strand in the first insulating coated portion of said coiled conductive strand; and

a second insulating coating formed over a second portion of said coiled conductive strand such that a second inline inductive element having a second inductance is formed, the current flowing along a curvature of said coiled conductive strand in the second insulating coated portion of said coiled conductive strand;

said first inductance being different from said second inductance.

10. The lead as claimed in claim 9, further comprising:

a ferrite material positioned in said first portion of said coiled conductive strand having said first insulating coating formed thereon.

11. The lead as claimed in claim 9, further comprising:

a ferrite material positioned in said second portion of said coiled conductive strand having said second insulating coating formed thereon.

12. The lead as claimed in claim 9, further comprising:

ferrite material positioned in said first and second portions of said coiled conductive strand having said first and second insulating coatings formed thereon.

13. A lead for medical applications that reduces the effects of MRI induced signals, comprising:

a coiled conductive strand forming a spring-like configuration such that current flows over a surface thereof, through contact points between adjacent loops of the coiled conductive strand;

a first adjustable resistive material formed over a first portion of said coiled conductive strand such that a first inline inductive element having a first inductance is formed, the current flowing along a curvature of said coiled conductive strand in the first adjustable resistive material portion of said coiled conductive strand;

a second adjustable resistive material formed over a second portion of said coiled conductive strand such that a second inline inductive element having a second inductance is formed, the current flowing along a curvature of said coiled conductive strand in the second adjustable resistive material portion of said coiled conductive strand;

said first inductance being different from said second inductance.

14. The lead as claimed in claim 13, further comprising:

a ferrite material positioned in said first portion of said coiled conductive strand having said first adjustable resistive material formed thereon.

15. The lead as claimed in claim 13, further comprising:

a ferrite material positioned in said second portion of said coiled conductive strand having said second adjustable resistive material formed thereon.

16. The lead as claimed in claim 13, further comprising:

ferrite material positioned in said first and second portions of said coiled conductive strand having said first and second adjustable resistive material formed thereon.

17. A lead for medical applications that reduces the effects of MRI induced signals, comprising:

two coiled conductive strands forming a spring-like configuration such that current flows over a surface thereof, through contact points between adjacent loops of the coiled conductive strands; and

an insulating coating formed over a portion of said two coiled conductive strands such that an inline inductive element is formed, the current flowing along a curvature of said two coiled conductive strands in the insulating coated portion of said two coiled conductive strands.

20. A lead for medical applications that reduces the effects of MRI induced signals, comprising:

two coiled conductive strands forming a spring-like configuration such that current flows over a surface thereof, through contact points between adjacent loops of the coiled conductive strands; and

an adjustable resistive material formed over a portion of said two coiled conductive strands such that an inline inductive element is formed, the current flowing along a curvature of said two coiled conductive strands in the adjustable resistive material portion of said two coiled conductive strands.

21. The lead as claimed in claim 20, further comprising:

a ferrite material positioned in said portion of said two coiled conductive strands having said adjustable resistive material formed thereon.

22. The lead as claimed in claim 20, wherein an inductance of the formed inline inductive element is adjusted by adjusting the resistive properties of the adjustable resistive material.

23. A lead for medical applications that reduces the effects of MRI induced signals, comprising:

a coiled conductive strand forming a spring-like configuration such that current flows over a surface thereof, through contact points between adjacent loops of said coiled conductive strand; and

an insulating coating formed over a portion of said coiled conductive strand such that an inline inductive element is formed, the current flowing along a curvature of said coiled conductive strand in the insulating coated portion of said coiled conductive strand.

24. The lead as claimed in claim 23, further comprising:

a ferrite material positioned in said portion of said coiled conductive strand having said insulating coating formed thereon.

25. The lead as claimed in claim 23, wherein an inductance of the formed inline inductive element being adjusted by adjusting a length of a region to which said insulating coating is formed over the portion of said two coiled conductive strands.

26. A lead for medical applications that reduces the effects of MRI induced signals, comprising:

a coiled conductive strand forming a spring-like configuration such that current flows over a surface thereof, through contact points between adjacent loops of said coiled conductive strand; and

an adjustable resistive material formed over a portion of said coiled conductive strand such that an inline inductive element is formed, the current flowing along a curvature of said coiled conductive strand in the adjustable resistive material portion of said coiled conductive strand.

27. The lead as claimed in claim 26, further comprising:

a ferrite material positioned in said portion of said coiled conductive strand having said adjustable resistive material formed thereon.

28. The lead as claimed in claim 26, wherein an inductance of the formed inline inductive element is adjusted by adjusting the resistive properties of the adjustable resistive material.