Imaging for use with moving organs

• US 20080221442A1
• Filed: 03/10/2008
• Published: 09/11/2008
• Est. Priority Date: 03/08/2007
• Status: Abandoned Application

• Current Assignee: Sync-Rx, Ltd. (Koninklijke Philips N.V.)
• Original Assignee: Sync-Rx, Ltd. (Koninklijke Philips N.V.)
• Inventors: Iddan, Gavriel, Tolkowsky, David
• Application Number:
  US12/075,244
• Publication Number:
  US 20080221442A1
• Time in Patent Office: Days
• US Class Current: 600/425
• CPC Class Codes: A61B 17/3207 Atherectomy devices working by cutting or abrading; Similar devices specially adapted for non-vascular obstructions A61B17/32037 takes precedence; endoscopic cutting instruments A61B17/320016
• 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 2017/00252 for by-pass connections, i.e. connections from heart chamber to blood vessel or from blood vessel to blood vessel
• CPC Class Codes: A61B 2017/00694 with means correcting for movement of or for synchronisation with the body
• CPC Class Codes: A61B 2017/00703 correcting for movement of heart, e.g. ECG-triggered
• CPC Class Codes: A61B 2017/22044 with a pointed tip
• CPC Class Codes: A61B 2017/22094 for crossing total occlusions, i.e. piercing
• CPC Class Codes: A61B 2090/3735 Optical coherence tomography [OCT]
• CPC Class Codes: A61B 2090/3762 using computed tomography systems [CT]
• CPC Class Codes: A61B 2090/3782 transmitter or receiver in catheter or minimal invasive instrument
• CPC Class Codes: A61B 2576/02 specially adapted for a particular organ or body part
• CPC Class Codes: A61B 5/0036 including treatment, e.g., using an implantable medical device, ablating, ventilating
• CPC Class Codes: A61B 5/02007 Evaluating blood vessel condition, e.g. elasticity, compliance
• CPC Class Codes: A61B 5/4836 Diagnosis combined with treatment in closed-loop systems or methods A61B5/0036 takes precedence
• CPC Class Codes: A61B 5/7289 Retrospective gating, i.e. associating measured signals or images with a physiological event after the actual measurement or image acquisition, e.g. by simultaneously recording an additional physiological signal during the measurement or image acquisition
• CPC Class Codes: A61B 6/12 Arrangements for detecting or locating foreign bodies
• CPC Class Codes: A61B 6/503 for diagnosis of the heart
• CPC Class Codes: A61B 6/504 for diagnosis of blood vessels, e.g. by angiography
• CPC Class Codes: A61B 6/5217 extracting a diagnostic or physiological parameter from medical diagnostic data
• CPC Class Codes: A61B 6/541 involving acquisition triggered by a physiological signal
• CPC Class Codes: A61B 8/0883 : for diagnosis of the heart
• CPC Class Codes: A61B 8/0891 : for diagnosis of blood vessels
• CPC Class Codes: A61B 8/543 : involving acquisition triggered by a physiological signal
• CPC Class Codes: A61B 90/37 : Surgical systems with images on a monitor during operation
• CPC Class Codes: A61F 2/958 : Inflatable balloons for placing stents or stent-grafts
• CPC Class Codes: A61M 2210/12 : Blood circulatory system
• CPC Class Codes: A61M 5/007 : for contrast media
• CPC Class Codes: G16H 50/30 : for calculating health indices; for individual health risk assessment

Abstract

Apparatus is described for imaging a portion of a body of a subject that moves as a result of cyclic activity of a body system of the subject and that also undergoes additional motion. An imaging device acquires a plurality of image frames of the portion. A sensor senses a phase of the cyclic activity of the body system. A control unit generates a stabilized set of image frames of the portion by identifying a given phase of the cyclic activity, and outputting a set of the image frames corresponding to image frames of the portion acquired during the given phase, and by image tracking at least the set of image frames to reduce imaged motion of the portion associated with the additional motion. A display displays the stabilized set of image frames of the portion. Other embodiments are also described.

Claims

1. Apparatus for imaging a portion of a body of a subject that moves as a result of cyclic activity of a first body system of the subject and that also undergoes additional motion, the apparatus comprising:

an imaging device for acquiring a plurality of image frames of the portion of the subject'"'"'s body;

a sensor for sensing a phase of the cyclic activity of the first body system;

a control unit configured to generate a stabilized set of image frames of the portion of the subject'"'"'s body;

by identifying a given phase of the cyclic activity of the first body system, and outputting a set of the image frames corresponding to image frames of the portion acquired during the given phase, and

by image tracking at least the set of image frames to reduce imaged motion of the portion of the subject'"'"'s body associated with the additional motion; and

a display configured to display the stabilized set of image frames of the portion of the subject'"'"'s body.

2. The apparatus according to claim 1, wherein the control unit is configured to identify the given phase of the cyclic activity using a gating signal, and wherein the display is configured to display a representation of the gating signal simultaneously with displaying the stabilized set of image frames.

3. The apparatus according to claim 1, wherein the display is configured to display an enlarged stabilized set of image frames of a region within the portion of the subject'"'"'s body.

4. The apparatus according to claim 1, wherein to generate the stabilized set of image frames of the portion of the subject'"'"'s body, the control unit is configured:

to identify a first image frame acquired during the given phase,

subsequently, to image track the first identified image frame,

subsequently, to identify a second image frame acquired during the given phase, and

subsequently, to image track the second identified image frame.

5. The apparatus according to claim 1, wherein to generate the stabilized set of image frames of the portion of the subject'"'"'s body, the control unit is configured:

to image track a first image frame,

subsequently, to place the first image tracked frame in the stabilized set of image frames if the first image tracked frame was acquired during the given phase,

subsequently to image track a second image frame, and

subsequently, to place the second image tracked frame in the stabilized set of image frames if the second image tracked frame was acquired during the given phase.

6. The apparatus according to claim 1, wherein to generate the stabilized set of image frames of the portion of the subject'"'"'s body, the control unit is configured:

to generate a gated set of image frames of the plurality of image frames corresponding to image frames of the portion acquired during the given phase, and

subsequently, to image track the gated set of image frames.

7. The apparatus according to claim 1, wherein to generate the stabilized set of image frames of the portion of the subject'"'"'s body, the control unit is configured:

to image track the plurality of image frames of the portion of the subject'"'"'s body, and

subsequently, to generate a set of image frames corresponding to those of the tracked image frames of the portion that were acquired during the given phase.

8. The apparatus according to claim 1, wherein the control unit comprises a video tracker selected from the group consisting of:

an edge tracker, a centroid tracker, a correlation tracker, and an object tracker, and wherein the control unit is configured to image track the at least the set of image frames using the selected video tracker.

9. The apparatus according to claim 1, wherein the control unit is configured to generate the set of image frames corresponding to image frames of the portion acquired during the given phase by controlling the imaging device to acquire the plurality of image frames only when the cyclic activity is at the given phase.

10. The apparatus according to claim 1,

wherein the imaging device is configured to acquire the plurality of image frames throughout the cyclic activity, and

wherein the control unit is configured to generate the set of image frames corresponding to image frames of the portion acquired during the given phase, by selecting image frames corresponding to image frames of the portion acquired during the given phase from the plurality of image frames.

11. The apparatus according to claim 1, further comprising a user interface, wherein the control unit is configured to receive an input from a user, via the user interface, and to select a phase of the cyclic activity as being the given phase in response to the input.

12. The apparatus according to claim 1, wherein the display is configured to display the plurality of acquired image frames simultaneously with displaying the stabilized set of image frames.

13. The apparatus according to claim 1, wherein the apparatus is configured for the display to display the stabilized set of image frames in real time with respect to the acquisition of the plurality of image frames by the imaging device.

14. The apparatus according to claim 1, wherein the apparatus is configured for the display to display the stabilized set of image frames within 4 seconds of the imaging device having imaged the plurality of image frames.

15. The apparatus according to claim 1, wherein the apparatus is configured for the display to display the stabilized set of image frames less than two cycles of the cyclic activity after the imaging device imaged the plurality of image frames.

16. The apparatus according to claim 1, wherein the apparatus is configured for the display to display the stabilized set of image frames during a medical procedure during which the imaging device images the plurality of image frames.

17. The apparatus according to claim 1, wherein the apparatus is configured to display the stabilized set of image frames subsequent to a medical procedure during which the imaging device imaged the plurality of image frames.

18. The apparatus according to claim 1, further comprising a data storage unit configured to store the stabilized set of image frames.

19. The apparatus according to claim 1, wherein the control unit is configured to enhance the stabilized set of image frames by image processing the stabilized set of image frames.

20. The apparatus according to claim 1, wherein the additional motion is not associated with cyclic activity of the subject'"'"'s body, and wherein the control unit is configured to reduce the imaged motion associated with the additional motion that is not associated with cyclic activity, by image tracking at least the set of image frames.

21. The apparatus according to claim 20, wherein the additional motion is associated with whole-body motion of the subject, and wherein the control unit is configured to reduce the imaged motion associated with the whole-body motion by image tracking at least the set of image frames.

22. The apparatus according to claim 1, further comprising:

a contrast agent; and

an injection tool configured to inject the contrast agent into a space within the portion of the subject'"'"'s body, wherein

the imaging device is configured to acquire at least one image frame of the space during the given phase, at a time when at least some of the contrast agent is present within the space, and

the display is configured to display the at least one image frame of the space overlaid on at least one same one of the stabilized set of image frames.

23. The apparatus according to claim 22,

wherein the imaging device is configured to acquire a first image frame of the space during the given phase of a first cycle of the cyclic activity, at a time when at least some of the contrast agent is present within the space,

wherein the imaging device is configured to acquire a second image frame of the space during the given phase of a second cycle of the cyclic activity, at a time when at least some of the contrast agent is present within the space, and

wherein the display is configured to display the first and the second image frame of the space overlaid on at least one same frame of the stabilized set of image frames.

24. The apparatus according to claim 22,

wherein the space includes a lumen containing an occlusion,

wherein the injection tool is configured to inject the contrast agent into the lumen on a proximal side of the occlusion and on a distal side of the occlusion,

wherein the imaging device is configured to acquire at least one image frame of the lumen on the proximal side of the occlusion during the given phase of a cycle of the cyclic activity, at a time when at least some of the contrast agent is present within the lumen on the proximal side of the occlusion,

wherein the imaging device is configured to acquire at least one image frame of the lumen on the distal side of the occlusion during the given phase of the cycle, at a time when at least some of the contrast agent is present within the lumen on the distal side of the occlusion, and

wherein the display is configured to display the at least one image frame of the lumen on the proximal side of the occlusion and the at least one image frame of the lumen on the distal side of the occlusion overlaid on at least one same frame of the stabilized set of image frames.

25. The apparatus according to claim 22,

wherein the space includes a lumen containing an occlusion,

wherein the injection tool is configured to inject the contrast agent into the lumen on a proximal side of the occlusion and on a distal side of the occlusion,

wherein the imaging device is configured to acquire at least one image frame of the lumen on the proximal side of the occlusion during the given phase of a first cycle of the cyclic activity, at a time when at least some of the contrast agent is present within the lumen on the proximal side of the occlusion,

wherein the imaging device is configured to acquire at least one image frame of the lumen on the distal side of the occlusion during the given phase of a second cycle of the cyclic activity, at a time when at least some of the contrast agent is present within the lumen on the distal side of the occlusion, and

wherein the display is configured to display the at least one image frame of the lumen on the proximal side of the occlusion and the at least one image frame of the lumen on the distal side of the occlusion overlaid on at least one same frame of the stabilized set of image frames.

26. The apparatus according to claim 22,

wherein the space includes a lumen containing an occlusion,

wherein the injection tool is configured to inject the contrast agent into the lumen on a proximal side of the occlusion,

further comprising a second injection tool configured to inject the contrast agent into the lumen on a distal side of the occlusion,

wherein the imaging device is configured to acquire at least one image frame of the lumen on the proximal side of the occlusion during the given phase of a cycle of the cyclic activity, at a time when at least some of the contrast agent is present within the lumen on the proximal side of the occlusion,

wherein the imaging device is configured to acquire at least one image frame of the lumen on the distal side of the occlusion during the given phase of the cycle, at a time when at least some of the contrast agent is present within the lumen on the distal side of the occlusion, and

wherein the display is configured to display the at least one image frame of the lumen on the proximal side of the occlusion and the at least one image frame of the lumen on the distal side of the occlusion overlaid on at least one same frame of the stabilized set of image frames.

27. The apparatus according to claim 22,

wherein the space includes a lumen containing an occlusion,

wherein the injection tool is configured to inject the contrast agent into the lumen on a proximal side of the occlusion,

further comprising a second injection tool configured to inject the contrast agent into the lumen on a distal side of the occlusion,

wherein the imaging device is configured to acquire at least one image frame of the lumen on the proximal side of the occlusion during the given phase of a first cycle of the cyclic activity, at a time when at least some of the contrast agent is present within the lumen on the proximal side of the occlusion,

wherein the imaging device is configured to acquire at least one image frame of the lumen on the distal side of the occlusion during the given phase of a second cycle of the cyclic activity, at a time when at least some of the contrast agent is present within the lumen on the distal side of the occlusion, and

wherein the display is configured to display the at least one image frame of the lumen on the proximal side of the occlusion and the at least one image frame of the lumen on the distal side of the occlusion overlaid on at least one same frame of the stabilized set of image frames.

28. The apparatus according to claim 22, wherein the imaging device comprises a fluoroscope.

29. The apparatus according to claim 22, wherein the space includes a space selected from the group consisting of a chamber of a heart of the subject, a lumen of a coronary blood vessel of the subject, and a lumen of an aorta of the subject, and wherein the injection tool is configured to inject the contrast agent into the selected space.

30. The apparatus according to claim 22, wherein the control unit is configured to construct at least one three-dimensional image frame of the space, during the given phase, based on image frames acquired at the time when at least some of the contrast agent is present within the space.

31. The apparatus according to claim 22, further comprising a medical tool configured to be inserted into the space, wherein the apparatus is configured to acquire an image of the tool while the tool is inside the space, and wherein the display is configured to display the image of the tool overlaid on the image frame of the space.

32. The apparatus according to claim 22, wherein the control unit is configured to identify when the injection tool injects the contrast agent by image processing a set of image frames of the space.

33. The apparatus according to claim 32, wherein the control unit is configured to identify when the injection tool injects the contrast agent by specifically analyzing a region of at least some of the plurality of image frames that corresponds to a vicinity of a distal tip of the injection tool.

34. The apparatus according to claim 33, wherein the control unit is configured to identify when the injection tool injects the contrast agent by determining a level of darkness of the region of at least some of the plurality of image frames that corresponds to the vicinity of the distal tip of the injection tool.

35. The apparatus according to claim 1, further comprising a user interface, wherein the display is configured to receive an input from a user, via the user interface, and to display a marking at a given position within the portion of the subject'"'"'s body within the stabilized set of image frames, in response to the input.

36. The apparatus according to claim 35, wherein the display is configured to display two or more views of the stabilized set of image frames of the portion of the subject'"'"'s body, and to display the marking at the given position within respective views of the stabilized set of image frames.

37. The apparatus according to claim 1, wherein the imaging device is further configured to image a plurality of images of a medical tool disposed within the portion of the subject'"'"'s body, and wherein the control unit is configured to generate a stabilized set of image frames of the medical tool.

38. The apparatus according to claim 37, wherein the medical tool includes a medical tool that is implanted within the portion of the subject'"'"'s body, and wherein the imaging device is configured to image a plurality of images of the implanted medical tool.

39. The apparatus according to claim 37, wherein the medical tool includes a medical tool that is transiently inserted within the portion of the subject'"'"'s body, and wherein the imaging device is configured to image a plurality of images of the medical tool while it is inserted within the portion.

40. The apparatus according to claim 37, wherein the control unit is configured to enhance the stabilized set of image frames of the medical tool by image processing the stabilized set of image frames of the medical tool.

41. The apparatus according to claim 1, wherein the control unit is configured to determine a physiological parameter of the subject by analyzing the stabilized set of image frames.

42. The apparatus according to claim 41, wherein the control unit is configured to determine a parameter relating to cardiac function of the subject by analyzing the stabilized set of image frames.

43. The apparatus according to claim 41, wherein the control unit is configured to determine a parameter relating to respiratory function of the subject by analyzing the stabilized set of image frames.

44. The apparatus according to claim 1, wherein, in generating the stabilized set of image frames, the control unit is configured to smoothen a transition between successive frames of the set of frames.

45. The apparatus according to claim 44, wherein the control unit is configured to smoothen the transition between the successive frames, by:

determining a characteristic of motion of an object within the stabilized set of image frames by image processing frames of the stabilized set of image frames,

generating a simulated image of the object by assuming that the object continues to move according to the determined profile, and

using the simulated image of the object as an intermediate image between successive image frames.

46. The apparatus according to claim 44, wherein the control unit is configured to smoothen the transition between the successive frames, by:

determining a position of an object within a non-gated image frame that was acquired subsequent to a first gated image frame and before a second gated image frame, and

generating a representation of the object within the stabilized set of image frames before the second gated image frame is generated within the stabilized set of image frames.

47. The apparatus according to claim 1, wherein the control unit is configured to determine a dimension of a region within the portion of the subject'"'"'s body, by analyzing the stabilized set of image frames.

48. The apparatus according to claim 47, wherein the control unit is configured to output an indication of a size of a medical tool relative to the region within the portion of the subject'"'"'s body.

49. The apparatus according to claim 47,

further comprising a medical tool configured to be inserted into the portion of the subject'"'"'s body and having a known dimension,

wherein the control unit is configured to determine the dimension of the region by comparing a dimension of the tool within the stabilized set of image frames to the known dimension.

50. The apparatus according to claim 49, wherein the medical tool comprises markers, the markers being separated from each other by a known distance, and wherein the control unit is configured to determine an orientation at which the medical tool is disposed within the portion of the subject'"'"'s body by determining a distance between the markers as viewed within the stabilized set of image frames with respect to the known distance.

51. The apparatus according to claim 50, wherein the control unit is configured to generate a simulated image of a virtual medical tool disposed at the orientation within the stabilized set of image frames of the portion of the subject'"'"'s body, in response to the determining of the distance.

52. The apparatus according to claim 1, further comprising a user interface, wherein the control unit is configured to receive an input from a user, via the user interface, and to generate a simulated image of a virtual medical tool disposed within the stabilized set of image frames of the portion of the subject'"'"'s body, in response to receiving the input.

53. The apparatus according to claim 52, wherein the control unit is configured to output dimensions of a real medical tool that corresponds to the simulated image of the virtual medical tool.

54. The apparatus according to claim 53, wherein the control unit is configured to output the dimensions of the real medical tool by accounting for an orientation at which the virtual medical tool is disposed within the simulated image.

55. The apparatus according to claim 53, wherein the control unit is configured to output the dimensions of the real medical tool by accounting for a curvature of a region of the portion of the subject'"'"'s body within which region the virtual medical tool is disposed within the simulated image.

56. The apparatus according to claim 53, wherein the control unit is configured to receive a first and a second input from the user and to generate respective simulated images of first and second medical tools being placed within the stabilized set of image frames of the portion of the subject'"'"'s body, in response to receiving the inputs.

57. The apparatus according to claim 1, wherein the imaging device comprises two or more imaging devices, and wherein the control unit is configured to generate two or more stabilized sets of image frames of the portion of the subject'"'"'s body, the sets of image frames having been imaged by respective imaging devices of the two or more imaging devices.

58. The apparatus according to claim 57, wherein a first imaging device of the two or more imaging devices is configured to image the portion of the subject'"'"'s body before a medical procedure, a second imaging device of the two or more imaging devices is configured to image the portion of the subject'"'"'s body during the medical procedure, and the control unit is configured to generate the stabilized sets of image frames during the medical procedure.

59. The apparatus according to claim 57, wherein a first imaging device of the two or more imaging devices is configured to image the portion of the subject'"'"'s body from outside the portion of the subject'"'"'s body, and a second imaging device of the two or more imaging devices is configured to image regions within the portion of the subject'"'"'s body while the second imaging device is disposed at respective locations within the portion of the subject'"'"'s body.

60. The apparatus according to claim 59, wherein the control unit is configured to associate (a) locations within the stabilized image frames acquired by the first imaging device that correspond to the respective locations of the second imaging device, with (b) respective image frames acquired by the second imaging device while the second imaging device was disposed at the respective locations.

61. The apparatus according to claim 60, further comprising a medical tool configured to be inserted into the portion of the subject'"'"'s body to a vicinity of the respective locations while the second imaging device is not disposed at the respective locations, wherein the control unit is configured to generate (a) respective image frames acquired by the second imaging device while the second imaging device was disposed at the respective locations, when (b) the medical tool is disposed in a vicinity of the respective locations.

62. The apparatus according to claim 60, wherein the first imaging device comprises a fluoroscope and the second imaging device comprises an intravascular ultrasound probe.

63. The apparatus according to claim 60, wherein the first imaging device comprises a CT scanner and the second imaging device comprises an intravascular ultrasound probe.

64. The apparatus according to claim 60, wherein the first imaging device is configured to acquire the plurality of image frames before the second imaging device images the regions within the portion of the subject'"'"'s body.

65. The apparatus according to claim 60, wherein the first imaging device is configured to acquire the plurality of image frames while the second imaging device images the regions within the portion of the subject'"'"'s body, and wherein the first imaging device is configured to acquire the plurality of image frames by acquiring a plurality of image frames of the second imaging device disposed within the portion.

66. The apparatus according to claim 1,

wherein the stabilized set of image frames defines a first stabilized set of image frames, and

wherein the control unit is configured to generate an additional stabilized set of image frames of the portion of the subject'"'"'s body,

by identifying a further given phase of the cyclic activity of the first body system, and generating an additional set of the image frames corresponding to image frames of the portion acquired during the further given phase, and

by image tracking at least some of the additional set of image frames to reduce imaged motion of the portion of the subject'"'"'s body associated with the additional motion.

67. The apparatus according to claim 66, wherein the given phase includes a systolic phase of a cardiac cycle of the subject and the further given phase includes a diastolic phase of the subject'"'"'s cardiac cycle, and wherein the control unit is configured to generate sets of image frames which are stabilized respectively to the systolic and to the diastolic phases of the subject'"'"'s cardiac cycle.

68. The apparatus according to claim 66, further comprising a user interface, wherein the control unit is configured to receive an input from a user, via the user interface, and to generate simulated images of a virtual medical tool disposed within the stabilized sets of image frames of the portion of the subject'"'"'s body at the given phase and at the further given phase, in response to receiving the input.

69. The apparatus according to claim 66, further comprising a medical tool disposed within the portion of the subject'"'"'s body, wherein the control unit is configured to generate stabilized images of the medical tool disposed within the portion of the subject'"'"'s body respectively at the given phase and at the further given phase.

70. The apparatus according to claim 66, wherein the control unit is configured to determine a physiological parameter of the subject by comparing the additional stabilized set of image frames to the first stabilized set of image frames.

71. The apparatus according to claim 70, wherein the control unit is configured to determine a parameter relating to cardiac function of the subject by comparing the additional stabilized set of image frames to the first stabilized set of image frames.

72. The apparatus according to claim 70, wherein the control unit is configured to determine a parameter relating to respiratory function of the subject by comparing the additional stabilized set of image frames to the first stabilized set of image frames.

73. The apparatus according to claim 1, wherein the cyclic activity includes a cardiac cycle of the subject, and wherein the sensor comprises a sensor for sensing a phase of the subject'"'"'s cardiac cycle.

74. The apparatus according to claim 73, wherein the given phase includes an end-diastolic phase of the subject'"'"'s cardiac cycle, and wherein the control unit is configured to generate a stabilized set of the image frames corresponding to image frames of the portion acquired during the end-diastolic phase of the subject'"'"'s cardiac cycle.

75. The apparatus according to claim 73, wherein the sensor comprises a blood pressure sensor.

76. The apparatus according to claim 73, wherein the sensor comprises an ECG sensor.

77. The apparatus according to claim 73, wherein the sensor comprises an image processor configured to sense a phase of the subject'"'"'s cardiac cycle by comparing image frames of the plurality of image frames to at least one of the image frames of the plurality of image frames.

78. The apparatus according to claim 1, wherein the cyclic activity includes a respiratory cycle of the subject, and wherein the sensor comprises a sensor for sensing a phase of the subject'"'"'s respiratory cycle.

79. The apparatus according to claim 78, wherein the sensor comprises an image processor configured to sense a phase of the subject'"'"'s respiratory cycle by comparing image frames of the plurality of image frames to at least one of the image frames of the plurality of image frames.

80. The apparatus according to claim 1, wherein the additional motion is a result of cyclic activity of a second body system of the subject, and wherein the control unit is configured to reduce imaged motion of the portion of the subject'"'"'s body associated with the cyclic activity of the second body system by image tracking at least the set of image frames.

81. The apparatus according to claim 80,

wherein the cyclic activity of the first body system has a greater frequency than the cyclic activity of the second body system, and

wherein the control unit is configured to generate the stabilized set of image frames of the portion of the subject'"'"'s body:

by identifying the given phase of the cyclic activity of the first body system, and outputting the set of the image frames corresponding to image frames of the portion acquired during the given phase, and

by image tracking at least the set of image frames to reduce imaged motion of the portion of the subject'"'"'s body associated with the cyclic activity of the second body system.

82. The apparatus according to claim 80,

wherein the cyclic activity of the first body system has a lower frequency than a frequency of the cyclic activity of the second body system, and

wherein the control unit is configured to generate the stabilized set of image frames of the portion of the subject'"'"'s body:

by identifying the given phase of the cyclic activity of the first body system, and outputting the set of the image frames corresponding to image frames of the portion acquired during the given phase, and

by image tracking at least the set of image frames to reduce imaged motion of the portion of the subject'"'"'s body associated with the cyclic activity of the second body system.

83. The apparatus according to claim 80,

wherein the cyclic activity of the first body system includes a cardiac cycle of the subject,

wherein the cyclic activity of the second body system includes a respiratory cycle of the subject, and

wherein the control unit is configured to generate the stabilized set of image frames of the portion of the subject'"'"'s body:

by identifying the given phase of the cardiac cycle, and outputting the set of the image frames corresponding to image frames of the portion acquired during the given phase, and

by image tracking at least the set of image frames to reduce imaged motion of the portion of the subject'"'"'s body associated with the respiratory cycle.

84. The apparatus according to claim 80,

wherein the cyclic activity of the first body system includes a respiratory cycle of the subject,

wherein the cyclic activity of the second body system includes a cardiac cycle of the subject, and

wherein the control unit is configured to generate the stabilized set of image frames of the portion of the subject'"'"'s body:

by identifying the given phase of the respiratory cycle, and outputting the set of the image frames corresponding to image frames of the portion acquired during the given phase, and

by image tracking at least the set of image frames to reduce imaged motion of the portion of the subject'"'"'s body associated with the cardiac cycle.

85. A method for imaging a portion of a subject'"'"'s body that moves as a result of cyclic activity of a first body system of the subject and that also undergoes additional motion, the method comprising:

acquiring a plurality of image frames of the portion of the subject'"'"'s body;

identifying a given phase of the cyclic activity of the first body system;

generating a stabilized set of image frames of the portion of the subject'"'"'s body

by outputting a set of image frames corresponding to image frames of the portion acquired during the given phase, and

by image tracking at least the set of image frames to reduce imaged motion of the portion of the subject'"'"'s body associated with the additional motion; and

displaying the stabilized image frames of the portion of the subject'"'"'s body.

86. The method according to claim 85,

wherein identifying the given phase comprises sensing a gating signal,

further comprising displaying a representation of the gating signal simultaneously with displaying the stabilized set of image frames.

87. The method according to claim 85, wherein generating the stabilized set of image frames comprises:

outputting a first one of the image frames of the set of image frames;

subsequently, image tracking the first one of the image frames;

subsequently, outputting a second one of the image frames of the set of image frames; and

subsequently, image tracking the second one of the image frames.

88. The method according to claim 85, wherein generating the stabilized set of image frames comprises:

image tracking a first image frame,

subsequently, placing the first image tracked frame in the stabilized set of image frames if the first image tracked frame was acquired during the given phase,

subsequently image tracking a second image frame, and

subsequently, placing the second image tracked frame in the stabilized set of image frames if the second image tracked frame was acquired during the given phase.

89. The method according to claim 85, wherein generating the stabilized set of image frames comprises:

generating a gated set of image frames of the plurality of image frames corresponding to image frames of the portion acquired during the given phase, and

subsequently, image tracking the gated set of image frames.

90. The method according to claim 85, wherein generating the stabilized set of image frames comprises:

image tracking the plurality of image frames of the portion of the subject'"'"'s body, and

subsequently, generating a set of image frames corresponding to those of the tracked image frames of the portion that were acquired during the given phase.

91. The method according to claim 85, wherein outputting the set of image frames comprises acquiring the plurality of image frames only when the cyclic activity is at the given phase.

92. The method according to claim 85, wherein acquiring the plurality of image frames comprises acquiring the plurality of image frames throughout the cyclic activity, and wherein outputting the set of image frames corresponding to image frames of the portion acquired during the given phase comprises selecting image frames corresponding to image frames of the portion acquired during the given phase, from the plurality of image frames.

93. The method according to claim 85, wherein displaying the stabilized set of image frames comprises displaying the stabilized set of image frames in real time relative to acquiring the plurality of image frames.

94. The method according to claim 85, wherein displaying the stabilized set of image frames comprises displaying the stabilized set of image frames within 4 seconds of acquiring the plurality of image frames.

95. The method according to claim 85, wherein displaying the stabilized set of image frames comprises displaying the stabilized set of image frames less than two cycles of the cyclic activity after acquiring the plurality of image frames.

96. The method according to claim 85, wherein displaying the stabilized set of image frames comprises displaying the stabilized set of image frames during a medical procedure during which the plurality of image frames are acquired.

97. The method according to claim 85, wherein displaying the stabilized set of image frames comprises displaying the stabilized set of image frames subsequent to a medical procedure during which the plurality of image frames are acquired.

98. The method according to claim 85, further comprising enhancing the stabilized set of image frames by image processing the stabilized set of image frames.

99. The method according to claim 85, wherein the additional motion is not associated with cyclic activity of the subject'"'"'s body, and wherein image tracking at least the set of image frames to reduce imaged motion comprises reducing the imaged motion associated with the additional motion that is not associated with cyclic activity.

100. The method according to claim 99, wherein the additional motion is associated with whole-body motion of the subject, and wherein image tracking at least the set of image frames to reduce imaged motion comprises reducing the imaged motion associated with the subject'"'"'s whole-body motion.

101. The method according to claim 85, further comprising:

injecting a contrast agent into a space within the portion of the subject'"'"'s body;

acquiring at least one image frame of the space during the given phase, at a time when at least some of the contrast agent is present within the space; and

displaying the at least one image frame of the space overlaid on at least some of the stabilized set of image frames.

102. The method according to claim 101,

wherein acquiring at least one image frame of the space during the given phase comprises:

acquiring a first image frame of the space during the given phase of a first cycle of the cyclic activity, at a time when at least some of the contrast agent is present within the space;

acquiring a second image frame of the space during the given phase of a second cycle of the cyclic activity, at a time when at least some of the contrast agent is present within the space; and

wherein displaying the at least one image frame of the space comprises displaying the first image frame of the space and the second image frame of the space overlaid on at least one same frame of the stabilized set of image frames.

103. The method according to claim 101,

wherein the space includes a lumen containing an occlusion,

wherein injecting the contrast agent into the space comprises injecting the contrast agent into the lumen on a proximal side of the occlusion and on a distal side of the occlusion, and

wherein acquiring at least one image frame of the space during the given phase comprises:

acquiring at least one image frame of the lumen on the proximal side of the occlusion during the given phase of a cycle of the cyclic activity, at a time when at least some of the contrast agent is present within the lumen on the proximal side of the occlusion; and

acquiring at least one image frame of the lumen on the distal side of the occlusion during the given phase of the cycle, at a time when at least some of the contrast agent is present within the lumen on the distal side of the occlusion, and

wherein displaying the at least one image frame of the space comprises displaying the at least one image frame of the lumen on the proximal side of the occlusion and the at least one image frame of the lumen on the distal side of the occlusion overlaid on at least one same frame of the stabilized set of image frames.

104. The method according to claim 101,

wherein the space includes a lumen containing an occlusion,

wherein injecting the contrast agent into the space comprises injecting the contrast agent into the lumen on a proximal side of the occlusion and on a distal side of the occlusion, and

wherein acquiring at least one image frame of the space during the given phase comprises:

acquiring at least one image frame of the lumen on the proximal side of the occlusion during the given phase of a first cycle of the cyclic activity, at a time when at least some of the contrast agent is present within the lumen on the proximal side of the occlusion; and

acquiring at least one image frame of the lumen on the distal side of the occlusion during the given phase of a second cycle of the cyclic activity, at a time when at least some of the contrast agent is present within the lumen on the distal side of the occlusion, and

wherein displaying the at least one image frame of the space comprises displaying the at least one image frame of the lumen on the proximal side of the occlusion and the at least one image frame of the lumen on the distal side of the occlusion overlaid on at least one same frame of the stabilized set of image frames.

105. The method according to claim 101, wherein the space includes a space selected from the group consisting of a chamber of a heart of the subject, a lumen of a coronary blood vessel of the subject, and a lumen of an aorta of the subject, and wherein injecting the contrast agent comprises injecting the contrast agent into the selected space.

106. The method according to claim 101, wherein acquiring at least one image frame of the space during the given phase comprises constructing at least one three-dimensional image frame of the space, during the given phase, based on image frames acquired at the time when at least some of the contrast agent is present within the space.

107. The method according to claim 101, further comprising identifying when the injection tool injects the contrast agent by image processing a set of image frames of the space.

108. The method according to claim 107, wherein identifying when the injection tool injects the contrast-agent comprises specifically analyzing a region of at least some of the plurality of image frames that corresponds to a vicinity of a distal tip of the injection tool.

109. The method according to claim 108, wherein specifically analyzing the region comprises determining a level of darkness of the region of at least some of the plurality of image frames that corresponds to the vicinity of the distal tip of the injection tool.

110. The method according to claim 85, further comprising displaying a marking at a given position within the portion of the subject'"'"'s body within the stabilized set of image frames.

111. The method according to claim 110, wherein displaying the stabilized set of image frames comprises displaying two or more views of the stabilized set of image frames of the portion of the subject'"'"'s body, and wherein displaying the marking comprises displaying the marking at the given position within respective views of the stabilized set of image frames.

112. The method according to claim 85, wherein acquiring the plurality of image frames comprises acquiring a plurality of image frames of a tool disposed within the portion of the subject'"'"'s body, and wherein displaying the stabilized set of image frames comprises displaying a stabilized set of image frames of the tool disposed within the portion.

113. The method according to claim 112, further comprising enhancing the stabilized set of image frames of the medical tool by image processing the stabilized set of image frames of the medical tool.

114. The method according to claim 85, further comprising determining a physiological parameter of the subject by analyzing the stabilized set of image frames.

115. The method according to claim 114, wherein determining the physiological parameter comprises determining a parameter relating to cardiac function of the subject.

116. The method according to claim 114, wherein determining the physiological parameter comprises determining a parameter relating to respiratory function of the subject.

117. The method according to claim 85, further comprising smoothening a transition between successive frames of the set of frames.

118. The method according to claim 117, wherein smoothening the transition comprises

determining a characteristic of motion of an object within the stabilized set of image frames by image processing frames of the stabilized set of image frames,

generating a simulated image of the object by assuming that the object continues to move according to the determined profile, and

using the simulated image of the object as an intermediate image between successive image frames.

119. The method according to claim 117, wherein smoothening the transition comprises:

determining a position of an object within a non-gated image frame that was acquired subsequent to a first gated image frame and before a second gated image frame; and

generating a representation of the object within the stabilized set of image frames before the second gated image frame is generated within the stabilized set of image frames.

120. The method according to claim 85, further comprising determining a dimension of a region within the portion of the subject'"'"'s body, by analyzing the stabilized set of image frames.

121. The method according to claim 120, further comprising generating an indication of a size of a medical tool relative to the region within the portion of the subject'"'"'s body.

122. The method according to claim 120,

further comprising inserting into the portion of the subject'"'"'s body a medical tool having a known dimension,

wherein determining the dimension of the region comprises comparing a dimension of the tool within the stabilized set of image frames to the known dimension.

123. The method according to claim 122, wherein the medical tool includes markers, the markers being separated from each other by a known distance, and wherein the method further comprises determining an orientation at which the medical tool is disposed within the portion of the subject'"'"'s body by determining a distance between the markers as viewed within the stabilized set of image frames with respect to the known distance.

124. The method according to claim 123, further comprising generating a simulated image of a virtual medical tool disposed at the orientation within the stabilized set of image frames of the portion of the subject'"'"'s body, in response to the determining of the orientation.

125. The method according to claim 85, further comprising generating a simulated image of a virtual medical tool disposed within the gated set of image frames of the portion of the subject'"'"'s body.

126. The method according to claim 125, further comprising generating dimensions of a real medical tool that corresponds to the simulated image of the virtual medical tool.

127. The method according to claim 126, wherein identifying the dimensions comprises accounting for an orientation at which the virtual medical tool is disposed within the simulated image.

128. The method according to claim 126, wherein identifying the dimensions comprises accounting for a curvature of a region of the portion of the subject'"'"'s body within which region the virtual medical tool is disposed within the simulated image.

129. The method according to claim 85,

wherein acquiring the plurality of image frames comprising acquiring image frames with at least first and second imaging devices, and

wherein displaying the stabilized set of image frames comprises displaying two or more stabilized sets of image frames, respective stabilized sets of image frames corresponding to image frames acquired by respective imaging devices of the at least first and second imaging devices.

130. The method according to claim 129,

wherein acquiring image frames with the first imaging device comprises acquiring image frames of the portion of the subject'"'"'s body before a medical procedure,

wherein acquiring image frames with the second imaging device comprises acquiring image frames of the portion of the subject'"'"'s body during the medical procedure, and

wherein displaying the gated sets of image frames comprises displaying the gated sets of image frames during the procedure.

131. The method according to claim 129,

wherein acquiring image frames with the first imaging device comprises acquiring external image frames of the portion of the subject'"'"'s body, from outside the portion of the subject'"'"'s body, and

wherein acquiring image frames with the second imaging device comprises acquiring internal image frames of regions within the portion of the subject'"'"'s body while the second imaging device is disposed at respective locations within the portion of the subject'"'"'s body.

132. The method according to claim 131, further comprising associating:

(a) respective locations within the stabilized set of external image frames acquired by the first imaging device that correspond to the respective locations of the second imaging device, with

(b) respective image frames acquired by the second imaging device while the second imaging device was disposed at the respective locations.

133. The method according to claim 132, further comprising:

removing the second imaging device from the respective locations;

inserting a medical tool into the portion subsequent to the second imaging device having been removed from the respective locations and while the second imaging device is not disposed at the respective locations; and

displaying (a) respective image frames acquired by the second imaging device while the second imaging device was disposed at the respective locations, when (b) the medical tool is disposed in a vicinity of the respective locations.

134. The method according to claim 132, wherein acquiring the image frames with the first imaging device comprises acquiring image frames with a fluoroscope, and wherein acquiring the image frames with the second imaging device comprises acquiring the image frames with an intravascular ultrasound probe.

135. The method according to claim 132, wherein acquiring the image frames with the first imaging device comprises acquiring image frames with a CT scanner, and wherein acquiring the image frames with the second imaging device comprises acquiring the image frames with an intravascular ultrasound probe.

136. The method according to claim 132, wherein acquiring image frames with the first imaging device comprises acquiring the image frames with the first imaging device before the acquisition of the image frames with the second imaging device.

137. The method according to claim 132, wherein acquiring image frames with the first imaging device comprises acquiring the image frames with the first imaging device while the second imaging device images the regions within the portion of the subject'"'"'s body, and wherein acquiring image frames with the first imaging device comprises acquiring image frames of the second imaging device disposed within the portion.

138. The method according to claim 85, further comprising generating an additional stabilized set of image frames of the portion of the subject'"'"'s body,

by identifying a further given phase of the cyclic activity of the first body system, and generating an additional set of the image frames corresponding to image frames of the portion acquired during the further given phase, and

by image tracking at least some of the additional set of image frames to reduce imaged motion of the portion of the subject'"'"'s body associated with the additional motion.

139. The method according to claim 138, further comprising displaying simulated images of a virtual medical tool disposed within the portion of the subject'"'"'s body respectively at the given phase and at the further given phase.

140. The method according to claim 138, further comprising displaying a stabilized set of image frames of a medical tool disposed within the portion of the subject'"'"'s body respectively at the given phase and at the further given phase.

141. The method according to claim 138, further comprising determining a physiological parameter of the subject by comparing the additional stabilized set of image frames to the first stabilized set of image frames.

142. The method according to claim 141, wherein determining the physiological parameter of the subject comprises determining a parameter relating to cardiac function of the subject.

143. The method according to claim 141, wherein determining the physiological parameter of the subject comprises determining a parameter relating to respiratory function of the subject.

144. The method according to claim 85, wherein the cyclic activity includes a cardiac cycle of the subject, and wherein identifying the given phase comprises identifying a phase of the subject'"'"'s cardiac cycle.

145. The method according to claim 144, wherein the given phase includes an end-diastolic phase of the subject'"'"'s cardiac cycle, and wherein identifying the given phase comprises identifying the end-diastolic phase of the subject'"'"'s cardiac cycle.

146. The method according to claim 144, wherein identifying the given phase comprises comparing image frames of the plurality of image frames to at least one of the image frames of the plurality of image frames.

147. The method according to claim 85, wherein the cyclic activity includes a respiratory cycle of the subject, and wherein identifying the given phase comprises identifying a phase of the subject'"'"'s respiratory cycle.

148. The method according to claim 147, wherein identifying the given phase comprises comparing image frames of the plurality of image frames to at least one of the image frames of the plurality of image frames.

149. The method according to claim 85, wherein the additional motion is a result of cyclic activity of a second body system of the subject, and wherein image tracking the at least the set of image frames comprises reducing imaged motion of the portion of the subject'"'"'s body associated with the cyclic activity of the second body system.

150. The method according to claim 149,

wherein the cyclic activity of the first body system has a greater frequency than a frequency of the cyclic activity of the second body system,

wherein outputting the set of the image frames comprises outputting a set of image frames of the portion acquired during the given phase of the first cycle, and

wherein image tracking at least the set of image frames comprises reducing imaged motion of the portion of the subject'"'"'s body associated with the cyclic activity of the second body system.

151. The method according to claim 149,

wherein the cyclic activity of the first body system has a lower frequency than a frequency of the cyclic activity of the second body system,

wherein outputting the set of the image frames comprises outputting a set of image frames of the portion acquired during the given phase of the first cycle, and

wherein image tracking at least the set of image frames comprises reducing imaged motion of the portion of the subject'"'"'s body associated with the cyclic activity of the second body system.

152. The method according to claim 149,

wherein the cyclic activity of the first body system includes a cardiac cycle of the subject,

wherein the cyclic activity of the second body system includes a respiratory cycle of the subject,

wherein outputting the set of the image frames comprises outputting a set of image frames of the portion acquired during a given phase of the cardiac cycle, and

wherein image tracking at least the set of image frames comprises reducing imaged motion of the portion of the subject'"'"'s body associated with the cyclic activity of the respiratory cycle.

153. The method according to claim 149,

wherein the cyclic activity of the first body system includes a respiratory cycle of the subject,

wherein the cyclic activity of the second body system includes a cardiac cycle of the subject,

wherein outputting the set of the image frames comprises outputting a set of image frames of the portion acquired during a given phase of the respiratory cycle, and

wherein image tracking at least the set of image frames comprises reducing imaged motion of the portion of the subject'"'"'s body associated with the cyclic activity of the cardiac cycle.

154. Apparatus for imaging a portion of a body of a subject that moves as a result of cyclic activity of a first body system of the subject and that also undergoes additional motion, and for use with an imaging device for acquiring a plurality of image frames of the portion of the subject'"'"'s body, a sensor for sensing a phase of the cyclic activity of the first body system, and a display configured to display image frames of the portion of the subject'"'"'s body, the apparatus comprising:

a control unit configured to generate a stabilized set of image frames of the portion of the subject'"'"'s body;

by identifying a given phase of the cyclic activity of the first body system, and outputting a set of the image frames corresponding to image frames of the portion acquired during the given phase,

by image tracking at least the set of image frames to reduce imaged motion of the portion of the subject'"'"'s body associated with the additional motion,

wherein the control unit is configured to output the stabilized set of image frames to be displayed on the display.

155. Apparatus for imaging a portion of a body of a subject that moves as a result of cardiac cyclic activity of the subject and that also undergoes additional motion that is at least partially a result of a respiratory cycle of the subject, the apparatus comprising:

an imaging device for acquiring a plurality of image frames of the portion of the subject'"'"'s body;

a sensor for sensing a phase of the cardiac cyclic activity;

a control unit configured to generate a stabilized set of image frames of the portion of the subject'"'"'s body;

by identifying a given phase of the cardiac cyclic activity, and outputting a set of the image frames corresponding to image frames of the portion acquired during the given phase, and

by image tracking at least the set of image frames to reduce imaged motion of the portion of the subject'"'"'s body associated with the additional motion; and

a display configured to display the stabilized set of image frames of the portion of the subject'"'"'s body.

156. A method for imaging a portion of a body of a subject that moves as a result of cardiac cyclic activity of the subject and that also undergoes additional motion that is at least partially a result of a respiratory cycle of the subject, the method comprising:

identifying a given phase of the cardiac cyclic activity;

generating a stabilized set of image frames of the portion of the subject'"'"'s body

by outputting a set of image frames corresponding to image frames of the portion acquired during the given phase, and

by image tracking at least the set of image frames to reduce imaged motion of the portion of the subject'"'"'s body associated with the additional motion; and

displaying the tracked set of image frames of the portion of the subject'"'"'s body.