System and method for magnetic-resonance-guided electrophysiologic and ablation procedures

• US 20030199755A1
• Filed: 04/28/2003
• Published: 10/23/2003
• Est. Priority Date: 11/04/1998
• Status: Active Grant

• Current Assignee: Johns Hopkins University
• Original Assignee: Johns Hopkins University
• Inventors: Berger, Ronald D., McVeigh, Elliot R., Halperin, Henry R., Atalar, Ergin, Calkins, Hugh, Lima, Joao, Lardo, Albert
• Granted Patent: US 7,155,271 B2
• Time in Patent Office: Days
• US Class Current: 600/411
• CPC Class Codes: A61B 18/1492 having a flexible, catheter-like structure, e.g. for heart ablation A61B18/1477 takes precedence
• CPC Class Codes: A61B 2017/00039 Electric or electromagnetic phenomena other than conductivity, e.g. capacity, inductivity, Hall effect
• CPC Class Codes: A61B 2017/00053 Mapping
• CPC Class Codes: A61B 2090/374 NMR or MRI
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 5/415 the glands, e.g. tonsils, adenoids or thymus
• CPC Class Codes: A61B 5/418 lymph vessels, ducts or nodes
• CPC Class Codes: A61B 90/36 Image-producing devices or illumination devices not otherwise provided for
• 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 33/34084 implantable coils or coils being geometrically adaptable to the sample, e.g. flexible coils or coils comprising mutually movable parts
• CPC Class Codes: G01R 33/4808 Multimodal MR, e.g. MR combined with positron emission tomography [PET], MR combined with ultrasound or MR combined with computed tomography [CT]
• CPC Class Codes: G01R 33/5601 involving use of a contrast agent for contrast manipulation, e.g. a paramagnetic, super-paramagnetic, ferromagnetic or hyperpolarised contrast agent

Abstract

A system and method for using magnetic resonance imaging to increase the accuracy of electrophysiologic procedures is disclosed. The system in its preferred embodiment provides an invasive combined electrophysiology and imaging antenna catheter which includes an RF antenna for receiving magnetic resonance signals and diagnostic electrodes for receiving electrical potentials. The combined electrophysiology and imaging antenna catheter is used in combination with a magnetic resonance imaging scanner to guide and provide visualization during electrophysiologic diagnostic or therapeutic procedures. The invention is particularly applicable to catheter ablation, e.g., ablation of atrial fibrillation. In embodiments which are useful for catheter ablation, the combined electrophysiology and imaging antenna catheter may further include an ablation tip, and such embodiment may be used as an intracardiac device to both deliver energy to selected areas of tissue and visualize the resulting ablation lesions, thereby greatly simplifying production of continuous linear lesions. The invention further includes embodiments useful for guiding electrophysiologic diagnostic and therapeutic procedures other than ablation. Imaging of ablation lesions may be further enhanced by use of MR contrast agents. The antenna utilized in the combined electrophysiology and imaging catheter for receiving MR signals is preferably of the coaxial or “loopless” type. High-resolution images from the antenna may be combined with low-resolution images from surface coils of the MR scanner to produce a composite image. The invention further provides a system for eliminating the pickup of RE energy in which intracardiac wires are detuned by filtering so that they become very inefficient antennas. An RF filtering system is provided for suppressing the MR imaging signal while not attenuating the RF ablative current. Steering means may be provided for steering the invasive catheter under MR guidance. Other ablative methods can be used such as laser, ultrasound, and low temperatures.

Claims

1. A method for performing an electrophysiological procedure, comprising the steps of:

placing a subject in a main magnetic field;

introducing an MR-compatible electrode catheter;

acquiring a magnetic resonance signal;

using magnetic resonance imaging to determine the location of said MR-compatible electrode catheter; and

,

using said MR-compatible electrode catheter to acquire electrical signals indicative of an electrophysiological state.

2. The method according to claim 1, wherein said electrical signals indicative of an electrophysiological state comprise intracardiac electrograms.

3. The method according to claim 1, wherein said MR-compatible electrode catheter includes a tip comprising gold.

4. The method according to claim 1, wherein said MR-compatible electrode catheter comprises an MR-visible material.

5. The method according to claim 3, wherein said MR-visible material comprises a metal.

6. The method according to claim 1, further comprising using a magnetic resonance contrast agent to enhance images acquired in said step of using magnetic resonance imaging to determine the location of said MR-compatible electrode catheter.

7. The method according to claim 1, wherein said step of acquiring a magnetic resonance signal comprises the step of using a magnetic resonance imaging antenna which is integral with said MR-compatible electrode catheter.

8. A method for treating cardiac arrhythmias, comprising the steps of:

placing a subject in a main magnetic field;

introducing an ablation catheter; and

,

using magnetic resonance imaging to visualize ablation lesions created using said ablation catheter.

9. The method according to claim 8, wherein said step of using magnetic resonance imaging comprises the step of using a catheter antenna to receive magnetic resonance signals.

10. The method according to claim 9, wherein said catheter antenna comprises a loopless antenna.

11. The method according to claim 9, wherein said catheter antenna comprises a loop antenna.

12. The method according to claim 8, further comprising the step of using a magnetic resonance contrast agent to enhance the visibility of said ablation lesions in MR images.

13. The method according to claim 12, wherein said step of using a magnetic resonance contrast agent comprises the step of using gadolinium-DTPA.

14. A system for performing ablation therapy, comprising:

ablation tip means for applying ablative energy to create ablation lesions;

catheter means for inserting said diagnostic electrodes into a region to be treated;

magnetic resonance antenna means, integral with said catheter means, for receiving magnetic resonance signals; and

,

means for analyzing said received magnetic resonance signals and for displaying an image of said region to be treated, whereby said means for inserting can be guided to said region to be treated.

15. The system for performing ablation therapy according to claim 14, further comprising:

a plurality of diagnostic electrodes.

16. The system for performing ablation therapy according to claim 14, wherein said magnetic resonance antenna means comprises a loopless antenna.

46. The system for performing ablation therapy according to claim 14, wherein said magnetic resonance antenna means comprises a loop antenna.

17. A system for magnetic resonance imaging-guided catheter ablation, comprising:

means for generating RF ablation current;

means for generating an RF magnetic resonance imaging signal in a first frequency range;

filter means for filtering said first frequency range from said RF ablation current.

18. The system according to claim 17, further comprising magnetic resonance antenna means for receiving induced magnetic resonance signals.

19. The system according to claim 18, wherein said magnetic resonance antenna means comprises an invasive catheter antenna.

20. The system according to claim 19, wherein said invasive catheter antenna comprises a loopless antenna.

21. The system according to claim 17, wherein said means for generating a RF magnetic resonance imaging signal comprises means for generating a 64 MHz RF magnetic resonance signal and wherein said filter means comprises means for filtering said resonance signal from said ablation signal.

22. The system according to claim 17, wherein said filter means comprises a low-pass filter.

23. The system according to claim 17, wherein said filter means comprises a multistage filter.

24. The system according to claim 17, wherein said filter means comprises means for filtering gradient-induced noise.

25. The system according to claim 24, wherein said means for filtering gradient-induced noise comprises a series of active filters which filter a different frequency range than the RF filters.

47. The system according to claim 24, wherein said means for filtering gradient-induced noise comprises a series of passive filters which filter a different frequency range than the RF filters.

26. A method for performing an electrophysiological procedure, comprising the steps of:

placing a subject in a main magnetic field;

introducing an invasive imaging antenna or coil;

acquiring a first magnetic resonance image from said invasive imaging antenna or coil;

acquiring a second magnetic resonance image from a surface coil;

combining said first and second magnetic resonance images to produce a composite image; and

,

using said composite image to guide said electrophysiological procedure.

27. The method according to claim 26, wherein said step of using said composite image to guide said electrophysiological procedure comprises the step of using said composite image to guide an ablation procedure.

28. The method according to claim 26, further comprising the step of using said composite image to construct a three-dimensional map of areas in the heart that have undergone ablation.

29. The method according to claim 26, further comprising the step of using said composite image to construct a three-dimensional rendering of the heart.

30. The method according to claim 29, further comprising the step of storing said three-dimensional rendering into a texture map of an imaging volume.

31. A system for magnetic resonance imaging-guided catheter ablation, comprising:

electrode means for receiving electrical signals indicative of an electrophysiological state, said electrical signals being within a first frequency range;

means for generating an RF magnetic-resonance-inducing signal;

magnetic resonance antenna means for receiving magnetic resonance signals from a region to be treated;

filter means for filtering said first frequency range from said RF magnetic-resonance-inducing signal.

32. A combined electrophysiology and imaging catheter, comprising:

at least one diagnostic electrode;

catheter for inserting said diagnostic electrode into a region to be studied; and

,

an invasive magnetic resonance antenna, integral with said catheter, for receiving magnetic resonance signals.

33. The combined electrophysiology and imaging catheter according to claim 32, further comprising:

steering device for deflecting said catheter, whereby said catheter can be steered to said region to be studied.

34. The combined electrophysiology and imaging catheter according to claim 33, wherein said steering device comprises a steering wire.

35. The combined electrophysiology and imaging catheter according to claim 34, wherein said steering wire is of a titanium construction.

36. The combined electrophysiology and imaging catheter according to claim 35, wherein said steering wire is housed in a sheath.

37. The combined electrophysiology and imaging catheter according to claim 33, wherein said steering device comprises a steering knob.

38. The combined electrophysiology and imaging catheter according to claim 37, wherein said steering knob is operable to move a steering wire toward or away from a distal tip of said catheter.

39. The combined electrophysiology and imaging catheter according to claim 32, further comprising:

an ablation tip for applying ablative energy to a region to be treated.

40. The combined electrophysiology and imaging catheter according to claim 32, further comprising:

a flexible antenna whip at a distal portion of said catheter.

41. The combined electrophysiology and imaging catheter according to claim 40, wherein said flexible antenna whip is coated with an insulating layer.

42. The combined electrophysiology and imaging catheter according to claim 40, wherein said flexible antenna whip comprises a tip which is formed into a J-shape to prevent perforation.

43. The combined electrophysiology and imaging catheter according to claim 32, wherein said catheter and all components housed therein are fabricated of materials having low-magnetic susceptibility.

44. The combined electrophysiology and imaging catheter according to claim 32, further comprising a tip which is at least 4 millimeters in length and suitable for use in RF ablation procedures.

45. The combined electrophysiology and imaging catheter according to claim 44, wherein said tip is fabricated from platinum.

48. The combined electrophysiology and imaging catheter according to claim 34, wherein said steering wire is of a non-magnetic construction.

49. The combined electrophysiology and imaging catheter according to claim 44, wherein said tip is fabricated from gold.