Catheter tracking with phase information

• US 20050245814A1
• Filed: 04/27/2005
• Published: 11/03/2005
• Est. Priority Date: 04/28/2004
• Status: Active Grant

• Current Assignee: Sunnybrook Health Sciences Centre
• Original Assignee: Sunnybrook and Women's College Health Sciences Centre
• Inventors: Anderson, Kevan J.T., Wright, Graham A.
• Granted Patent: US 7,505,808 B2
• Time in Patent Office: Days
• US Class Current: 600/410
• CPC Class Codes: A61B 2034/2051 Electromagnetic tracking systems
• CPC Class Codes: A61B 5/06 Devices, other than using radiation, for detecting or locating foreign bodies for removing same A61B17/50 ; determining position of probes within or on the body of the patient
• CPC Class Codes: G01R 33/287 involving active visualization of interventional instruments, e.g. using active tracking RF coils or coils for intentionally creating magnetic field inhomogeneities

Abstract

The present invention discloses a method for determining the position and/or orientation of a catheter or other interventional access device or surgical probe using phase patterns in a magnetic resonance (MR) signal. In the method of the invention, global two-dimensional correlations are used to identify the phase pattern and orientation of individual microcoils, which is unique for each microcoil'"'"'s position and orientation. In a preferred embodiment of the invention, tracking of interventional devices is performed by one integrated phase image projected onto the axial plane and a second image in an oblique plane through the center of the coil and normal to the coil plane. In another preferred embodiment, the position and orientation of a catheter tip can be reliably tracked using low resolution MR scans clinically useful for real-time interventional MRI applications. In a further preferred embodiment, the invention provides real-time computer control to track the position of endovascular access devices and interventional treatment systems, including surgical tools and tissue manipulators, devices for in vivo delivery of drugs, angioplasty devices, biopsy and sampling devices, devices for delivery of RF, thermal, microwave or laser energy or ionizing radiation, and internal illumination and imaging devices, such as catheters, endoscopes, laparoscopes, and related instruments.

Claims

1. A method of determining the position and/or orientation of a medical device in a patient'"'"'s body, the method comprising the steps of:

a) placing the medical device in a patient'"'"'s body and placing the patient in a magnetic resonance imaging scanner, the magnetic resonance imaging scanner having means for producing magnetic resonance signals having a phase and magnitude and detection means for detecting magnetic resonance signals, and the medical device including at least one marker for perturbing the phase of the magnetic resonance signal;

b) acquiring magnetic resonance signals with perturbed phase from the patient'"'"'s body using the detection means; and

c) reconstructing from the acquired magnetic resonance signals with perturbed phase at least one map of the spatial distribution of the phase of the received signals, and using selected characteristics of the spatial distribution of the phase to determine the device position and/or orientation of the at least one marker in the patient'"'"'s body.

2. The method of claim 1 wherein the at least one marker is at least one microcoil.

3. The method of claim 2 wherein the at least one map of the spatial distribution of the phase comprise at least one image in an oblique plane through a center of the microcoil and normal to an axial plane, where the axial plane is defined as being perpendicular to the direction of a main static magnetic field of the magnetic resonance system.

4. The method of claim 3 wherein the at least one map of the spatial distribution of the phase also comprises at least one integrated phase image projected onto the axial plane.

5. The method of claim 4 wherein step c) of reconstructing from the acquired magnetic resonance signals at least one map of the spatial distribution of the phase of the received signals includes

producing an axial projection image of the microcoil'"'"'s sensitivity pattern, determining a position of the microcoil in an axial plane based on lines of constant phase which extend in a radial direction from the microcoil'"'"'s edges,

determining a roll angle θ

of the microcoil from an angle at which the phase pattern is rotated with respect to a reference axial phase pattern,

prescribing an oblique slice, perpendicular to the axial plane, through a center of the coil and perpendicular to the plane in which the coil lies and then determining a location of the coil in a third orthogonal direction by noting that discontinuities in the oblique phase pattern extend radially from the coil'"'"'s edges,

determining a pitch angle φ

by calculating an angle at which the oblique phase pattern is rotated with respect to a reference phase pattern; and

determining a normal of the microcoil wherein the roll angle θ and

the pitch angle φ

from two Euler angles used to determine the normal of the microcoil.

6. The method of claim 1 wherein the magnetic resonance signals are acquired using a magnetic resonance reception coil located external to the body.

7. The method of claim 1 wherein the at least one marker is connected electrically to the detection means of the magnetic resonance system and magnetic resonance signals are electrically transmitted from the at least one marker to the detection means.

8. The method of claim 1 wherein the at least one marker is coupled optically or inductively to a transducer which is electrically connected to the detection means of the magnetic resonance imager.

9. The method of claim 1 wherein the at least one marker is attached to a side of the medical device.

10. The method of claim 1 wherein the medical device has a tubular structure and has a longitudinal axis, and wherein the at least one active marker extends about a circumference of the tubular structure in a plane perpendicular to the longitudinal axis of the device.

11. The method of claim 1 wherein the medical device has a longitudinal axis, and wherein the at least one active marker is a plurality of markers disposed along the longitudinal axis of the medical device.

12. The method of claim 1 wherein the medical device has a leading end portion inserted first into the patient'"'"'s body, and wherein the at least one marker is attached to the medical device at the leading end portion thereof.

13. The method of claim 1 wherein the medical device has a longitudinal axis, and wherein the at least one marker is a distribution of markers disposed along a length of the medical device, and wherein the distribution of markders along the length of the catheter defines the MR-visible region of the medical device such that an MR image is obtained for any orientation of the medical device.

14. The method of claim 1 wherein the at least one marker is mounted on the medical device so that it can move and rotate inside a housing forming part of the medical device.

15. The method of claim 1 wherein the at least one marker comprises at least one small piece of ferromagnetic material affixed to the medical device which disrupts the magnetic field in a local vicinity of the ferromagnetic material.

16. The method of claim 1 wherein the magnetic resonance signals are acquired using a magnetic resonance reception coil located external to the body.

17. The method of claim 1 wherein the at least one marker comprises a small bubble of an effective gas contained in a balloon attached to the medical device, the effective gas being selected so that a difference in magnetic susceptibility between the effective gas and adjacent water in the body yields unique phase patterns in the magnetic resonance signals around the balloon.

18. The method of claim 17 wherein the effective gas is carbon dioxide.

19. The method of claim 17 wherein the magnetic resonance signals are acquired using a magnetic resonance reception coil located external to the body.

20. The method of claim 1 wherein the medical device is a catheter, an endoscope, a laparoscope, an electrophysiology electrode, or other related device.

21. The method of claim 1 including tracking position and orientation of a medical device using low resolution magnetic resonance scans clinically useful for real-time interventional magnetic resonance imaging applications.

22. The method of claim 1 including providing real-time computer control to track the position of endovascular access devices and interventional treatment systems, including surgical tools and tissue manipulators, devices for in vivo delivery of drugs, angioplasty devices, biopsy and sampling devices, devices for delivery of RF, thermal, microwave or laser energy or ionizing radiation, and internal illumination and imaging devices, such as catheters, endoscopes, laparoscopes, and related instruments.

23. The method of claim 2 wherein the at least one microcoil is two microcoils placed in orthogonal directions to each other.

24. The method of claim 1 wherein the at least one marker is selected so that a difference in magnetic susceptibility between the marker and adjacent water in the patient'"'"'s body yields unique phase patterns in the signal around the marker which can be mapped using the MR signal received by an external coil.

25. The method of claim 2 wherein said at least one microcoil has a radius a which satisfies a condition, a<

FOV/10, where FOV is a field of view.

26. A method for determining the position and orientation of a medical device inserted into a body of a patient, comprising the steps of:

inserting a medical device into a body of a patient, the medical device including at least one microcoil;

detecting phase patterns with perturbed phase in a magnetic resonance (MR) signal emitted by the microcoil;

determining the position and orientation of the medical device in the patient'"'"'s body by producing an axial projection image of the at least one microcoil'"'"'s sensitivity pattern, determining a position of the at least one microcoil in an axial plane based on lines of constant phase which extend in a radial direction from the at least one microcoil'"'"'s edges,

determining a roll angle θ

of the at least one microcoil from an angle at which the phase pattern is rotated with respect to a reference axial phase pattern,

prescribing an oblique slice, perpendicular to the axial plane, through a center of the at least one microcoil and perpendicular to the plane in which the at least one microcoil lies and then determining a location of the coil in a third orthogonal direction by noting that discontinuities in the oblique phase pattern extend radially from the at least one microcoil'"'"'s edges,

determining a pitch angle φ

by calculating an angle at which the oblique phase pattern is rotated with respect to a reference phase pattern; and

determining a normal of the at least one microcoil wherein the roll angle θ and

the pitch angle φ

form two Euler angles used to determine the normal of the at least one microcoil.

27. The method of claim 26 wherein the magnetic resonance signals are acquired using a magnetic resonance reception coil located external to the body.

28. The method of claim 26 wherein the microcoil is electrically connected to the detection means of the magnetic resonance system and magnetic resonance signals are electrically transmitted from the at least one microcoil to the detection means.

29. The method of claim 26 wherein the microcoil is coupled optically or inductively to a transducer which is electrically connected to the detection means of the magnetic resonance imager.

30. The method of claim 26 wherein the medical device has a tubular structure and has a longitudinal axis, and wherein the at least one microcoil extends about a circumference of the tubular structure in a plane perpendicular to the longitudinal axis of the device.

31. The method of claim 26 wherein the at least one microcoil is attached to a side of the medical device.

32. The method of claim 26 wherein the medical device has a longitudinal axis, and wherein the at least one microcoil is a plurality of microcoils disposed along the longitudinal axis of the medical device.

33. The method of claim 26 wherein the medical device has a leading end portion inserted first into the patient'"'"'s body, and wherein the at least one microcoil is attached to the medical device at the leading end portion thereof.

34. The method of claim 33 wherein the medical device has a longitudinal axis, and wherein the at least one microcoil is a distribution of microcoils disposed along a length of the medical device, and wherein the distribution of microcoils along the length of the catheter defines the MR-visible region of the medical device such that an MR image is obtained for any orientation of the medical device.

35. The method of claim 26 wherein the at least one microcoil is mounted on the medical device so that it can move and rotate inside a housing forming part of the medical device.

36. The method of claim 26 wherein the medical device is a catheter, an endoscope, a laparoscope, an electrophysiology electrode, or other related device.

37. The method of claim 26 wherein the at least one microcoil has a shape which is one of circular, ellipsoidal and square.

38. The method of claim 26 wherein the at least one microcoil is two microcoils placed in orthogonal directions to each other.

39. The method of claim 26 wherein said at least one microcoil has a radius a which satisfies a condition, a<

FOV/10, where FOV is a field of view.

40. An apparatus for determining the position and/or orientation of a medical device in a patient'"'"'s body, the method comprising the steps of:

a) medical device for insertion into a patient'"'"'s body, the medical device including at least one marker for perturbing the phase of a magnetic resonance signal;

b) a magnetic resonance imaging scanner, the magnetic resonance imaging scanner having means for producing magnetic resonance signals having a phase and magnitude and detection means for detecting magnetic resonance signals; and

c) the magnetic resonance imaging scanner including processing means for reconstructing from the acquired magnetic resonance signals with perturbed phase at least one map of the spatial distribution of the phase of the received signals, and using selected characteristics of the spatial distribution of the phase to determine the device position and/or orientation of the at least one marker in the patient'"'"'s body.

41. The apparatus of claim 40 wherein the at least one marker is selected so that a difference in magnetic susceptibility between the marker and adjacent water in the body yields unique phase patterns in the signal around the marker which can be mapped using the MR signal received by an external coil.

42. The apparatus of claim 40 wherein the at least one marker comprises at least one microcoil.

43. The apparatus of claim 42 wherein the at least one microcoil has a shape which is one of a circular, ellipsoidal and square.

44. The apparatus of claim 42 wherein the at least one microcoil has a radius a which satisfies a condition, a<

FOV/10, where FOV is a field of view.

45. The apparatus of claim 40 wherein the magnetic resonance signals are acquired using a magnetic resonance reception coil located external to the body.

46. The apparatus of claim 40 wherein the at least one marker is a microcoil, and wherein said microcoil is connected electrically to the detection means of the magnetic resonance system and magnetic resonance signals are electrically transmitted from the at least one marker to the detection means.

47. The apparatus of claim 40 wherein the at least one marker is a microcoil, and wherein said microcoil is coupled optically or inductively to a transducer which is electrically connected to the detection means of the magnetic resonance imager.

48. The apparatus of claims 40 wherein the medical device has a tubular structure and has a longitudinal axis, and wherein the at least one marker is at least one microcoil, and wherein said microcoil extends about a circumference of the tubular structure in a plane perpendicular to the longitudinal axis of the device.

49. The apparatus of claim 40 wherein the at least one marker is attached to a side of the medical device.

50. The apparatus of any one of claim 40 wherein the medical device has a longitudinal axis, and wherein the at least one marker is a plurality of microcoils disposed along the longitudinal axis of the medical device.

51. The apparatus of claim 40 wherein the medical device has a leading end portion inserted first into the patient'"'"'s body, and wherein the at least one marker is attached to the medical device at the leading end portion thereof.

52. The apparatus of any one of claims 42 wherein the medical device has a longitudinal axis, and wherein the at least one microcoil is a distribution of microcoils disposed along a length of the medical device, and wherein the distribution of microcoils along the length of the catheter defines the MR-visible region of the medical device such that an MR image is obtained for any orientation of the medical device.

53. The apparatus of any one of claims 40 wherein the at least one marker is at least two microcoils placed in orthogonal directions to each other.