CONTACT OVER-TORQUE WITH THREE-DIMENSIONAL ANATOMICAL DATA

• US 20110022029A1
• Filed: 07/06/2010
• Published: 01/27/2011
• Est. Priority Date: 12/20/2004
• Status: Active Grant

• Current Assignee: Stereotaxis, Inc.
• Original Assignee: Stereotaxis, Inc.
• Inventors: Viswanathan, Raju R.
• Granted Patent: US 8,369,934 B2
• Time in Patent Office: Days
• US Class Current: 604/523
• CPC Class Codes: A61B 1/00158 using magnetic field
• CPC Class Codes: A61B 34/73 Manipulators for magnetic surgery
• 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: A61B 5/1076 for measuring dimensions inside body cavities, e.g. using catheters A61B3/1005 takes precedence
• CPC Class Codes: A61B 5/283 Invasive
• CPC Class Codes: A61B 5/6885 Monitoring or controlling sensor contact pressure

Abstract

A method is provided for establishing contact of a medical device against a three-dimensional surface geometry within a subject body, the method comprising obtaining a three-dimensional tissue surface geometry of an anatomical region within the subject body, obtaining a target location on the surface for the device to contact, determining local surface geometry information in a neighborhood of the target location, and using this information to determine a change of at least one control variable for effecting an over-torque of the medical device to enhance contact of the device with the target surface.

Claims

1. A method for establishing enhanced contact of a medical device against a three-dimensional surface geometry within a subject body, the method comprising obtaining a target location on the surface for the device to contact, obtaining local surface geometry information in a neighborhood of the target location, and using this information to determine a change of at least one control variable for effecting an over-torque of the medical device to enhance contact of the device with the target surface.

2. The method of claim 1, where the local surface geometry information includes the local surface normal.

3. The method of claim 1, where the local surface geometry information includes the local surface normal and curvature information.

4. The method of claim 3, where the curvature information consists of principal curvature directions obtained from an analysis of the deviation away from the local tangent plane of a local surface patch.

5. The method of claim 1 wherein the medical device is a magnetically navigable device.

6. The method of claim 2 wherein the medical device is a magnetically navigable device.

7. The method of claim 3 wherein the medical device is a magnetically navigable device.

8. The method of claim 4 wherein the medical device is a magnetically navigable device.

9. The method of claim 6 wherein the change of at least one variable comprises a rotation of an externally applied magnetic field vector to over-torque the medical device for enhanced contact.

10. The method of claim 7 wherein the change of at least one variable comprises a rotation of an externally applied magnetic field vector to over-torque the medical device for enhanced contact.

11. The method of claim 8 wherein the change of at least one variable comprises a rotation of an externally applied magnetic field vector to over-torque the medical device for enhanced contact.

12. The method of claim 1 wherein the three-dimensional surface geometry is a pre-operative image that is suitably registered with the subject body.

13. The method of claim 1 wherein the three-dimensional surface geometry is obtained from an anatomical map derived from a localization system that maps the local surface geometry.

14. The method of claim 3 wherein at least two points within the local tangent plane containing the target location point, that are spaced a predetermined distance from the target, are used to measure the deviation away from the local tangent plane of a local surface patch.

15. The method of claim 1 wherein the medical device is a computational virtual device in a three-dimensional model of the surface geometry.

16. The method of claim 1 wherein the medical device is a localized device sending tip position and orientation data to a remote navigation system used for device actuation and control.

17. The method of claim 2 wherein the at least one control variable may be changed to effect a movement of the virtual medical device to predict the over-torque of the actual medical device against the target surface.

18. The method of claim 14 wherein the deviation away from the local tangent plane is found by a stepping process that comprises incrementally moving a minimum distance from the at least two points, and determining whether a threshold has been crossed to determine if the surface is negatively curved or positively curved.

19. The method of claim 3 wherein the at least one control variable may be changed based on whether the surface has at least one direction of negative curvature.

20. The method of claim 4 wherein the at least one control variable may be changed based on whether the surface has at least one direction of negative curvature.

28. The method of claim 20 wherein the three-dimensional surface geometry is a pre-operative image that is suitably registered with the subject body.

29. The method of claim 20 wherein the three-dimensional surface geometry is obtained from a localization system that maps the local surface geometry.

21. A method for establishing contact of a magnetically navigable medical device against a three-dimensional surface geometry within a subject body, the method comprising:

obtaining a three dimensional tissue surface geometry of an anatomical region within a subject body;

identifying a desired target location on the tissue surface and a local plane tangent to the target location;

defining at least two points within the local tangent plane which are spaced a predetermined distance from the desired target;

incrementally stepping a minimum distance from the at least two points in a direction opposite the outward normal to the tangent plane, to determine whether a surface threshold has been crossed;

determining a rotation of a magnetic field vector that will provide an over-torque magnetic field for improving the contact of a medical device with the target surface; and

applying the over-torque magnetic field to force the medical device against the target surface.

22. The method of claim 21 wherein the crossing of the threshold is determined within a model of the three-dimensional surface geometry.

23. The method of claim 21 wherein the medical device is a virtual device in a three-dimensional model of the surface geometry, and the stepping process is performed within the model to determine if an image surface threshold is crossed.

24. The method of claim 21 wherein the medical device is a localized device in a three-dimensional model of the surface geometry, and the stepping process is performed within the model to determine if an image surface threshold is crossed

25. The method of claim 23 wherein the rotation of a field vector to over-torque the magnetic field may be utilized to effect a movement of the virtual medical device and to predict the over-torque of the medical device against the target surface.

26. The method of claim 24 wherein the step of determining whether a threshold has been crossed determines if the surface has at least one direction of negative curvature.

27. The method of claim 26 wherein the rotation of the magnetic field vector is based on whether the surface has at least one direction of negative curvature.

30. The method of claim 21 wherein the incremental stepping process comprises incrementally moving a minimum distance from the at least two points, and determines whether a threshold has been crossed to discern if the surface is negatively curved or positively curved.

31. The method of claim 30 wherein the at least two points are spaced a predetermined distance from the target, and the two points are within the local tangent plane containing the target location point.

32. The method of claim 31 wherein the predetermined distance is in the range of 4 to 7 millimeters.

33. The method of claim 32 wherein the incremental stepping of a minimum distance is in the range of about 1 to 5 millimeters.

34. The method of claim 21, wherein the applying of a magnetic field comprises a magnetic navigation system applying a magnetic field that leads the orientation of the medical device tip by a pre-determined amount in the same plane as that of the device.

35. The method of claim 21, wherein the applying of a magnetic field comprises a magnetic navigation system applying a magnetic field that leads the orientation of the medical device tip by a user-selected amount in the same plane as that of the device.

36. The method of claim 21 wherein the method further comprises comparing the angular lag between the magnetic field vector and the actual orientation of the tip of the medical device to determine whether the medical device has established over-torque contact.

37. A method for determining a control variable for establishing over-torque of a medical device against a three-dimensional tissue surface geometry within a subject body, the method comprising obtaining local surface geometry information in an anatomical region of a subject body, identifying a desired target location on the surface, defining at least one point spaced from the desired target, evaluating an image model of the surface at the at least one point for the presence of an image threshold crossing, and determining a change of at least one control variable based on the evaluation for effecting an over-torque of a medical device to improve contact of the device against the surface.