Location sensing with real-time ultrasound imaging

• US 6,773,402 B2
• Filed: 02/19/2002
• Issued: 08/10/2004
• Est. Priority Date: 07/10/2001
• Status: Active Grant

• Current Assignee: Biosense, Inc. (Cardinal Health, Inc.)
• Original Assignee: Biosense, Inc. (Cardinal Health, Inc.)
• Inventors: Beletsky, Ilya, Govari, Assaf
• Primary Examiner(s): Ruhl, Dennis W.
• Assistant Examiner(s): Jung, William C.
• Application Number:
  US10/078,746
• Publication Number:
  US 20030013958A1
• Time in Patent Office: 903 Days
• Field of Search: 600/437-472
• US Class Current: 600/459
• 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 2562/043 in a linear array
• CPC Class Codes: A61B 5/062 using magnetic field
• CPC Class Codes: A61B 5/1076 for measuring dimensions inside body cavities, e.g. using catheters A61B3/1005 takes precedence
• CPC Class Codes: A61B 5/287 Holders for multiple electrodes, e.g. electrode catheters for electrophysiological study [EPS]
• CPC Class Codes: A61B 8/0833 involving detecting or locating foreign bodies or organic structures
• CPC Class Codes: A61B 8/0841 for locating instruments
• CPC Class Codes: A61B 8/0858 involving measuring tissue layers, e.g. skin, interfaces
• CPC Class Codes: A61B 8/12 in body cavities or body tracts, e.g. by using catheters catheters per se A61M25/00
• CPC Class Codes: A61B 8/4254 using sensors mounted on the probe
• CPC Class Codes: A61B 8/445 Details of catheter construction
• CPC Class Codes: A61B 8/483 involving the acquisition of a 3D volume of data
• CPC Class Codes: A61B 8/488 involving Doppler signals
• CPC Class Codes: G01S 15/8929 using a three-dimensional transducer configuration
• CPC Class Codes: G01S 15/8993 Three dimensional imaging systems
• CPC Class Codes: G01S 7/5208 with integration of processing functions inside probe or scanhead

Abstract

Apparatus for mapping a surface of a cavity within a body of a subject includes an elongate probe, having a longitudinal axis and including a distal portion adapted for insertion into the cavity. A primary acoustic transducer on the distal portion of the probe is adapted to emit acoustic waves while the probe is in the cavity. A plurality of secondary acoustic transducers, distributed along the longitudinal axis over the distal portion of the probe, are adapted to receive the acoustic waves after reflection of the waves from the surface of the cavity and to generate, responsive to the received waves, electrical signals indicative of times of flight of the waves.

Claims

1. Apparatus for mapping a surface of a cavity within a body of a subject, comprising:

an elongate probe, having a longitudinal axis and comprising a distal portion adapted for insertion into the cavity;

a primary acoustic transducer on the distal portion of the probe, adapted to emit acoustic waves while the probe is in the cavity;

a plurality of secondary acoustic transducers, distributed along the longitudinal axis over the distal portion of the probe, which are adapted to receive the acoustic waves after reflection of the waves from the surface of the cavity and to generate, responsive to the received waves, electrical signals indicative of times of flight of the waves; and

control circuitry, adapted to receive and to process the electrical signals generated by the secondary acoustic transducers so as to reconstruct a three-dimensional shape of the surface of the cavity based on the times of flight, wherein the circuitry is operative to distinguish the signals generated responsive to the waves that have undergone one reflection from the surface of the cavity from the signals generated responsive to the waves that have undergone multiple reflections, and to reject the signals due to the waves that have undergone the multiple reflections.

2. Apparatus according to claim 1, wherein the apparatus comprises apparatus for mapping a chamber of the heart of the subject, and wherein the probe comprises an intracardiac catheter.

3. Apparatus according to claim 1, wherein the primary acoustic transducer comprises a phased array ultrasound transducer.

4. Apparatus according to claim 1, wherein the primary acoustic transducer comprises an ultrasound transducer configured only for non-phased array operation.

5. Apparatus according to claim 1, wherein the secondary acoustic transducers comprise ultrasound transducers configured only for non-phased array operation.

6. Apparatus according to claim 1, wherein the probe comprises at least one position sensor, which is adapted to generate a position signal indicative of position coordinates of the probe within the body.

7. Apparatus according to claim 6, and comprising control circuitry, adapted to process the electrical signals generated by the secondary acoustic transducers responsive to the position signal, so as to reconstruct a three-dimensional shape of the surface of the cavity based on the times of flight and the position signal.

8. Apparatus according to claim 6, wherein the position sensor comprises a coil, and wherein the position signal comprises an electrical current induced in the coil by an externally-applied magnetic field.

9. Apparatus according to claim 6, wherein the at least one position sensor comprises a plurality of position sensors.

10. Apparatus according to claim 9,

wherein one of the plurality of position sensors is disposed on the probe near a first subset of the secondary acoustic transducers, and wherein another one of the plurality of position sensors is disposed on the probe near a second subset of the secondary acoustic transducers, and

wherein the apparatus comprises control circuitry, adapted to process the electrical signals generated by the secondary acoustic transducers responsive to position signals generated by the first and second position sensors, so as to reconstruct a three-dimensional shape of the surface of the cavity based on the times of flight and the position signals.

11. Apparatus according to claim 1, wherein responsive to the times of flight, the circuitry is adapted to determine distances from the secondary acoustic transducers to respective points on the surface of the cavity, and to combine the determined distances so as to reconstruct the shape.

12. Apparatus according to claim 1, wherein the circuitry is adapted to detect a spectral shift in the acoustic waves received by the secondary acoustic transducers and to determine, responsive to the spectral shift, a velocity of motion of the surface.

13. Apparatus according to claim 1, and comprising a display, which is driven by the circuitry to display an image of the three-dimensional shape.

14. Apparatus according to claim 1, wherein the primary acoustic transducer is adapted to emit a plurality of bursts of acoustic waves from a respective plurality of dispositions within the cavity,

wherein the secondary acoustic transducers are adapted to receive the bursts of acoustic waves after reflection of the bursts from the surface of the cavity, and to generate, responsive to the received bursts, electrical signals indicative of times of flights of the bursts, and

wherein the circuitry is adapted to reconstruct the three-dimensional shape of the surface based on the times of flight of the bursts.

15. Apparatus according to claim 14, wherein the primary acoustic transducer is adapted to be moved through the plurality of dispositions by a user of the apparatus.

16. Apparatus according to claim 1, wherein the cavity has a wall, and the surface comprises an inner surface of the wall and an outer surface of the wall, and wherein the circuitry is adapted to distinguish the signals generated responsive to the waves that have been reflected from the inner surface from the signals generated responsive to the waves that have been reflected from the outer surface.

17. Apparatus according to claim 16, wherein the circuitry is operative to determine a thickness of the wall responsive to the signals generated by the waves that have been reflected from the inner surface and the waves that have been reflected from the outer surface.

18. Apparatus according to claim 1, and comprising one or more electrodes disposed on the distal portion of the probe, which are adapted to convey electrical signals to the circuitry responsive to electrical activity in the cavity, wherein the circuitry is adapted, responsive to the signals from the electrodes, to superimpose an indication of the electrical activity on the three-dimensional shape of the surface.

19. Apparatus according to claim 18, wherein the indication of the electrical activity comprises a map of electrical potentials at the surface of the cavity, which is registered with the three-dimensional shape of the surface.

20. Apparatus according to claim 1, and comprising a plurality of reference transducers outside the body, which are adapted to transmit acoustic waves into the body, such that the waves are received by the secondary acoustic transducers on the probe, causing the secondary acoustic transducers to generate electrical reference signals, and wherein the circuitry is adapted to process the reference signals so as to determine position coordinates of the probe.

21. Apparatus according to claim 20, wherein responsive to the determined position coordinates, the circuitry is adapted to define a position of the three-dimensional shape within the body.

22. Apparatus according to claim 1, and comprising one or more electrodes disposed on the distal portion of the probe, which are adapted to detect electrical activity in the cavity.

23. Apparatus according claim 22, wherein the one or more electrodes are adapted to detect varying electrical potentials at the surface of the cavity.

24. Apparatus according to claim 23, wherein the one or more electrodes comprise an array of non-contact electrodes, which are adapted to detect the varying electrical potentials at the surface, substantially without making contact with the surface.

25. A method for mapping a surface of a cavity within a body of a subject, comprising:

inserting a probe into the cavity, the probe having a longitudinal axis;

emitting acoustic waves within the cavity from a primary point on the probe;

receiving the acoustic waves at each of a plurality of secondary points distributed along the longitudinal axis of the probe, following reflection of the emitted waves from the surface of the cavity;

analyzing the received waves to determine times of flight of the waves;

reconstructing a three-dimensional shape of the surface of the cavity based on the determined times of flight, by determining, responsive to the times of flight, distances from the secondary points to corresponding points on the surface of the cavity generally opposite the secondary points, and combining the determined distances so as to reconstruct the shape, and distinguishing the waves received at the secondary points after one reflection from the surface of the cavity from the waves received after multiple reflections, and rejecting the waves received after the multiple reflections.

26. A method according to claim 25, wherein emitting the acoustic waves comprises emitting the waves in a phased array mode.

27. A method according to claim 25, wherein emitting the acoustic waves comprises emitting the waves in a non-phased array mode.

28. A method according to claim 25, wherein receiving the acoustic waves at the secondary points comprises receiving the acoustic waves by non-phased array ultrasound transducers.

29. A method according to claim 25, wherein inserting the probe into the cavity comprises inserting an intracardiac catheter into a chamber of the heart of the subject.

30. A method according to claim 25, wherein emitting and receiving the waves comprise emitting and receiving the waves while the probe is held substantially stationary at a single location in the cavity, and wherein

reconstructing the three-dimensional shape comprises reconstructing the shape based substantially only on the waves received at the single location.

31. A method according to claim 25, and comprising determining position coordinates of the probe inside the body, wherein reconstructing the three-dimensional shape comprises reconstructing the shape responsive to the coordinates.

32. A method according to claim 31, wherein reconstructing the shape comprises defining a position of the shape inside the body using the coordinates.

33. A method according to claim 31, wherein emitting and receiving the waves comprise emitting and receiving the waves at a plurality of different locations of the probe in the cavity, and wherein reconstructing the shape comprises reconstructing the shape based on the waves received at the different locations, using the coordinates of the probe determined at the different locations.

34. A method according to claim 31, wherein determining the position coordinates comprises transmitting and receiving reference acoustic waves between reference points outside the body and the points on the probe, and analyzing the received reference waves to find distances between the reference points and the points on the probe, thus to determine the position coordinates.

35. A method according to claim 31, wherein determining the position coordinates comprises determining the coordinates using a position sensor in the probe.

36. A method according to claim 35, wherein determining the coordinates comprises detecting electrical current induced in a coil of the probe by an externally-applied magnetic field.

37. A method according to claim 25, wherein the cavity has a wall, and the surface comprises an inner surface of the wall and an outer surface of the wall, and wherein determining the distances comprises distinguishing the waves received at the secondary points after reflection from the inner surface from the waves received after reflection from the outer surface.

38. A method according to claim 37, wherein reconstructing the shape comprises determining a thickness of the wall by comparing the times of flight of the waves received after reflection from the inner surface to those of the waves received after reflection from the outer surface.

39. A method according to claim 25, and comprising analyzing the received waves to detect a spectral shift therein, so as to determine, responsive to the spectral shift, a velocity of motion of the surface.

40. A method according to claim 39, wherein reconstructing the shape comprises generating a map of the cavity that includes an indication of the velocity of motion of different areas of the surface.

41. A method according to claim 25, and comprising sensing electrical activity in the cavity using electrical sensors on the probe.

42. A method according to claim 41, wherein sensing the electrical activity comprises detecting varying electrical potentials at the surface of the cavity substantially without contact between the electrical sensors on the probe and the surface.

43. A method according to claim 41, wherein reconstructing the shape comprises superimposing an indication of the electrical activity on the reconstructed three-dimensional shape of the surface.

44. A method according to claim 43, wherein superimposing the indication of the electrical activity comprises generating a map of electrical potentials at the surface of the cavity, and registering the map with the three-dimensional shape of the surface.