Catheter localization system

• US 8,825,134 B2
• Filed: 09/14/2007
• Issued: 09/02/2014
• Est. Priority Date: 09/14/2007
• Status: Active Grant

• Current Assignee: Siemens Healthcare GMBH (Siemens AG)
• Original Assignee: Siemens AG
• Inventors: Danehorn, Kenneth
• Primary Examiner(s): EVOY, NICHOLAS LANE
• Application Number:
  US11/855,737
• Publication Number:
  US 20090076483A1
• Time in Patent Office: 2,545 Days
• Field of Search: 600/382, 600/373, 600/424, 600/547, 128/899, 129/899
• US Class Current: 600/424
• CPC Class Codes: A61B 2034/2051 Electromagnetic tracking systems
• CPC Class Codes: A61B 2034/2053 Tracking an applied voltage gradient
• CPC Class Codes: A61B 34/20 Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis
• CPC Class Codes: A61M 2025/0166 Sensors, electrodes or the like for guiding the catheter to a target zone, e.g. image guided or magnetically guided
• CPC Class Codes: A61M 25/01 Introducing, guiding, advancing, emplacing or holding catheters A61M25/10 takes precedence

Abstract

A system and method for localizing a catheter is provided. Distance values are determined between a plurality of reference electrodes and a catheter electrode. At least two circles are identified based on the distance values. The catheter electrode is located at a position where the at least two circles substantially coincide or within a minimum distance between the at least two circles. A transformation is applied to the at least two circles to express the at least two circles in a global coordinate system. An image is displayed as a function of the catheter electrode position.

Claims

1. A method for localizing a catheter, the method comprising:

providing a catheter electrode, C, and a plurality of reference electrodes, R1, R2, R3, and R4;

determining distance values between R1 and C, R2 and C, R1 and R2, R3 and C, R4 and C, and R3 and R4;

identifying first and second triangles based on the distance values between (1) R1 and C, R2 and C, R1 and R2, and (2) R3 and C, R4 and C, and R3 and R4, respectively;

determining first and second orthogonal distances within the first and second triangles, respectively;

identifying a first circle having a radius equal to the first orthogonal distance and a second circle having a radius equal to the second orthogonal distance;

determining a position of the catheter electrode where the first and second circles substantially coincide or are within a minimum distance between the first and second circles;

applying a transformation to the first and second circles to express the first and second circles in a global coordinate system; and

displaying an image as a function of the position of the catheter electrode.

2. The method of claim 1, wherein the transformation is an Euler transformation.

3. The method of claim 1, wherein determining the distance values includes determining the distance values based on an impedance or voltage potential.

4. The method of claim 1, further comprising:

translating origins of the first and second circles to the position of the catheter electrode before applying the transformation.

5. The method of claim 1, further comprising:

repositioning the first and second circles, after applying the transformation; and

solving for a global coordinate value of the catheter electrode based on where the first and second circles substantially coincide or the minimum distance between the first and second circles.

6. The method of claim 1, further comprising:

registering the plurality of reference electrodes in the global coordinate system.

21. The method of claim 1, wherein R2 and R4 represent a same reference electrode.

7. A system for localizing a catheter, the system comprising:

an electrode, C, on a catheter;

a plurality of reference electrodes, comprising at least reference electrodes R1, R2, R3, and R4, each reference electrode of the plurality of reference electrodes configured to transmit or receive a signal to or from the electrode, respectively; and

a processor operable to determine distance values between R1 and C, R2 and C, R1 and R2, R3 and C, R4 and C, and R3 and R4, and determine a position of the electrode by identifying first and second circles based on the distance values and applying a transformation to the first and second circles to express the first and second circles in a global coordinate system,

wherein the electrode is located at a position where the first and second circles substantially coincide or within a minimum distance between the first and second circles, and

wherein identifying the first and second circles comprises determining first and second orthogonal distances within first and second triangles, respectively, dimensions of the first and second triangles being associated with the distance values between (1) R1 and C, R2 and C, R1 and R2, and (2) R3 and C, R4 and C, and R3 and R4, and the first and second orthogonal distances being the radius for the first and second circles, respectively.

8. The system of claim 7, wherein the transformation is an Euler transformation.

9. The system of claim 7, wherein the plurality of reference electrodes further comprises reference electrodes R5, R6, R7, and R8, and wherein the plurality of reference electrodes comprises six reference electrodes positioned on a body surface and two reference catheter electrodes.

10. The system of claim 7, wherein the processor is operable to determine the distance values based on an electrical characteristic associated with the respective signal.

11. The system of claim 10, wherein the electrical characteristic comprises an impedance or voltage potential.

12. The system of claim 7, wherein the processor is further operable to determine the position of the electrode of the catheter by translating origins of the first and second circles to the position of the electrode of the catheter before the transformation.

13. The system of claim 7, wherein the processor is further operable to determine, after applying the transformation, the position of the electrode of the catheter by repositioning the first and second circles and solving for a global coordinate value of the electrode of the catheter.

18. The system of claim 7, further comprising:

a catheter generator configured to generate a first signal having a first signal frequency and transmit the first signal from the electrode on the catheter;

a reference generator configured to generate a second signal having a second signal frequency and to transmit the second signal from a first reference electrode of the plurality of reference electrodes,

wherein the second signal frequency is substantially similar to the first signal frequency but is phase shifted relative to the first signal, such that a current is created between the electrode on the catheter and the first reference electrode.

19. The system of claim 18, wherein the processor is operable to determine the distance values based on a voltage potential difference, created by the current, measured between the electrode on the catheter and the first reference electrode.

22. The system of claim 7, wherein R2 and R4 represent a same reference electrode.

14. In a computer-readable medium having stored therein instructions executable by a processor, the instructions comprising:

providing a catheter electrode, C, and a plurality of reference electrodes, R1, R2, R3, and R4;

determining distance values between R1 and C, R2 and C, R1 and R2, R3 and C, R4 and C, and R3 and R4;

identifying first and second triangles based on the distance values between (1) R1 and C, R2 and C, R1 and R2, and (2) R3 and C, R4 and C, and R3 and R4, respectively;

determining first and second orthogonal distances within the first and second triangles, respectively;

determining first and second circles based on the first and second orthogonal distances, respectively;

determining a position of the catheter electrode where the first and second circles are the closest; and

applying a transformation to the first and second circles, the transformed first and second circles being in a global coordinate system.

15. The instructions of claim 14, wherein the transformation is an Euler transformation.

16. The instructions of claim 14, further comprising:

translating origins of the first and second circles to the position of the catheter electrode before the transformation.

17. The instructions of claim 14, further comprising:

repositioning the first and second circles, after the transformation; and

solving for a global coordinate value of the catheter electrode based on where the first and second circles are the closest.

20. The instructions of claim 14, wherein determining the first orthogonal distance comprises determining a first shortest distance, r₁, between a point between R1 and R2, and the catheter electrode;

and

wherein determining the second orthogonal distance comprises determining a second shortest distance, r₂, between a point between R3 and R4, and the catheter electrode.

23. The instructions of claim 14, wherein R2 and R4 represent a same reference electrode.