Methods, systems, and computer program products for imaging using virtual extended shear wave sources

• US 20040068184A1
• Filed: 10/07/2002
• Published: 04/08/2004
• Est. Priority Date: 10/07/2002
• Status: Active Grant

• Current Assignee: Duke University
• Original Assignee: Duke University
• Inventors: McAleavey, Stephen, Nightingale, Kathryn R., Trahey, Gregg E., Nightingale, Roger W.
• Granted Patent: US 6,764,448 B2
• Time in Patent Office: Days
• US Class Current: 600/437
• CPC Class Codes: A61B 8/08 Detecting organic movements or changes, e.g. tumours, cysts, swellings A61B8/02 - A61B8/06 take precedence
• CPC Class Codes: A61B 8/485 involving measuring strain or elastic properties
• CPC Class Codes: G01S 15/8927 using simultaneously or sequentially two or more subarrays or subapertures
• CPC Class Codes: G01S 7/52022 using a sequence of pulses, at least one pulse manipulating the transmissivity or reflexivity of the medium

Abstract

Ultrasound energy is transmitted into tissue in a first direction to provide a virtual extended shear wave source. The virtual extended shear wave source generates an extended shear wave that propagates in a second direction substantially orthogonal to the first direction to cause movement in the first direction of tissue that is offset from the virtual extended shear wave source in the second direction. Related ultrasound imaging systems and computer program products are also disclosed.

Claims

1. A method of scanning tissue, the method comprising transmitting ultrasound energy into tissue in a first direction to provide a virtual extended shear wave source that generates an extended shear wave that propagates in a second direction substantially orthogonal to the first direction to cause movement in the first direction of tissue that is offset from the virtual extended shear wave source in the second direction.

2. A method according to claim 1 further comprising:

tracking the movement of the offset tissue in response to the extended shear wave.

3. A method according to claim 1 wherein the extended shear wave causes the second tissue to move opposite the first direction.

4. A method according to claim 1 wherein the ultrasound energy is transmitted by an ultrasound transducer array having an associated focal point, wherein the extended shear wave is located on at least one of a far side and a near side of the focal point relative to the ultrasound transducer array.

5. A method according to claim 1 wherein the virtual extended shear wave source comprises a transmit ultrasound beam having an amplitude sufficient to generate a trackable extended shear wave.

6. A method according to claim 1 wherein the virtual extended shear wave source has an associated frequency in a range between about 1 MHz and about 25 MHz.

7. A method according to claim 1 wherein transmitting comprises transmitting ultrasound energy from an ultrasound transducer array having an associated focal point, wherein a portion of the virtual extended shear wave source extends at least a portion of a distance between the ultrasound transducer array and the focal point.

8. A method according to claim 1 wherein the first direction defines a substantially orthogonal angle with an ultrasound transducer array used to transmit the ultrasound energy.

9. A method according to claim 1 wherein the first direction defines less than a substantially orthogonal angle with an ultrasound transducer array used to transmit the ultrasound energy.

10. A method according to claim 1 wherein transmitting comprises transmitting first ultrasound energy in the first direction to provide a first virtual extended shear wave source that generates a first extended shear wave, the method further comprising:

transmitting second ultrasound energy into the tissue in a third direction to provide a second virtual extended shear wave source, wherein the second virtual extended shear wave source generates a second extended shear wave that propagates substantially orthogonal to the third direction to cause movement in the third direction of tissue that is offset from the second virtual extended shear wave source.

11. A method according to claim 10 wherein transmitting the first and second ultrasound energy into the tissue comprises transmitting the first and second ultrasound energy into the tissue substantially simultaneously.

12. A method according to claim 11 wherein the first and second virtual extended shear wave sources intersect one another in the tissue.

13. A method according to claim 11 wherein the first and second virtual extended shear wave sources do not intersect one another in the tissue.

14. A method according to claim 1 wherein the virtual extended shear wave comprises a first virtual extended shear wave, the method further comprising:

steering the transmitted ultrasound energy into the tissue in a third direction of transmission, that is different than the first, to provide a second virtual extended shear wave source in the tissue.

15. A method according to claim 1 wherein the virtual extended shear wave source comprises a first virtual extended shear wave source, the method further comprising:

changing a sub-aperture of an ultrasound transducer array used to transmit the ultrasound energy to provide a second virtual extended shear wave source in the tissue in a third direction.

16. A method according to claim 14 wherein steering comprises applying a phased excitation to an ultrasound transducer to steer the transmitted ultrasound energy in the third direction.

17. A method according to claim 14 wherein changing comprises changing a location of a sub-aperture of an ultrasound transducer array used to transmit the ultrasound energy.

18. A method according to claim 2 further comprising:

determining a displacement map including displacement values associated with respective portions of the tissue subject to the extended shear wave based on the tracking.

19. A method according to claim 18 wherein the transmitting is preceded by imaging the tissue to determine initial locations of the tissue prior to generation of the extended shear wave in the tissue;

and

wherein the determining comprises determining the displacement map based on the initial locations and the tracking.

20. A method according to claim 19 further comprising:

generating an image of the offset tissue based on the determined displacement map.

21. A method according to claim 1 wherein a length of the virtual extended shear wave source is in a range between about 0.2 mm and about 8.0 cm.

22. A method according to claim 2 wherein the tracking comprises tracking the movement of the offset tissue in response to the extended shear wave using receive mode parallel processing.

23. A method according to claim 2 wherein the transmitting comprises transmitting ultrasound energy into tissue using a first modality;

and

wherein tracking comprises tracking the movement of the offset tissue in response to the extended shear wave using a second modality.

24. A method according to claim 2 wherein tracking comprises tracking in at least one dimension.

25. A method according to claim 1 wherein transmitting comprises applying an excitation to an ultrasound transducer used to transmit the ultrasound energy.

26. A method according to claim 1 wherein transmitting comprises transmitting unfocused ultrasound energy into the tissue to provide the virtual extended shear wave source.

27. A method according to claim 1 wherein the virtual extended shear wave source further generates a second extended shear wave that propagates opposite the second direction.

28. A method according to claim 1 wherein the transmitted ultrasound energy causes the tissue along the first direction to displace in a range between about 0.1 μ

m and about 300 μ

m.

29. A method of scanning tissue using ultrasound, the method comprising transmitting ultrasound energy into tissue in a first direction to provide a virtual extended shear wave source that generates an extended shear wave that propagates in a second direction substantially orthogonal to the first direction to cause movement in the first direction of tissue that is offset from the virtual extended shear wave source in the second direction, wherein the ultrasound energy has an associated amplitude sufficient to allow the extended shear wave to be tracked.

30. A method according to claim 29 wherein an associated frequency of the virtual extended shear wave source is a range between about 1 MHz and about 25 MHz.

31. A method of imaging tissue using shear wave ultrasound, the method comprising:

tracking tissue to obtain first position data associated with tissue;

transmitting ultrasound energy into the tissue in a first direction to provide a virtual extended shear wave source that generates an extended shear wave that propagates in a second direction substantially orthogonal to the first direction to cause movement in the first direction of tissue that is offset from the virtual extended shear wave source in the second direction;

tracking the offset tissue to obtain second position data;

determining a displacement map based on the first and second position data; and

generating an image of the tissue based on the displacement map.

32. A method according to claim 31 wherein tracking comprises tracking using receive mode parallel processing.

33. A method according to claim 31 wherein the virtual extended shear wave source comprises a first virtual extended shear wave source that generates a first extended shear wave and the image comprises a first image, the method further comprising:

transmitting second ultrasound energy in a third direction, that is different than the first direction, to provide a second virtual extended shear wave source that generates a second extended shear wave that propagates orthogonal to the third direction to cause movement in the third direction of tissue that is offset from the second virtual extended shear wave source; and

tracking the second extended shear wave to obtain third position data;

determining a second displacement map based on the third position data; and

generating a second image of the tissue based on the second displacement map.

34. A system of scanning tissue, the system comprising means for transmitting ultrasound energy into tissue in a first direction to provide a virtual extended shear wave source that generates an extended shear wave that propagates in a second direction substantially orthogonal to the first direction to cause movement in the first direction of tissue that is offset from the virtual extended shear wave source in the second direction.

35. A system according to claim 34 further comprising:

means for tracking the movement of the offset tissue in response to the extended shear wave.

36. A system according to claim 34 wherein the extended shear wave causes the second tissue to move opposite the first direction.

37. A system according to claim 34 wherein the ultrasound energy is transmitted by an ultrasound transducer array having an associated focal point, wherein the extended shear wave is located on at least one of a far side and a near side of the focal point relative to the ultrasound transducer array.

38. A system according to claim 34 wherein the virtual extended shear wave source comprises a transmit ultrasound beam having an amplitude sufficient to generate a trackable extended shear wave.

39. A system according to claim 34 wherein the virtual extended shear wave source has an associated frequency in a range between about 1 MHz and about 25 MHz.

40. A system according to claim 34 wherein the means for transmitting comprises means for transmitting ultrasound energy from an ultrasound transducer array having an associated focal point, wherein a portion of the virtual extended shear wave source extends at least a portion of a distance between the ultrasound transducer array and the focal point.

41. A system according to claim 34 wherein the first direction defines a substantially orthogonal angle with an ultrasound transducer array used to transmit the ultrasound energy.

42. A system according to claim 34 wherein the first direction defines less than a substantially orthogonal angle with an ultrasound transducer array used to transmit the ultrasound energy.

43. A system according to claim 34 wherein the means for transmitting comprises means for transmitting first ultrasound energy in the first direction to provide a first virtual extended shear wave source that generates a first extended shear wave, the system further comprising:

means for transmitting second ultrasound energy into the tissue in a third direction to provide a second virtual extended shear wave source, wherein the second virtual extended shear wave source generates a second extended shear wave that propagates substantially orthogonal to the third direction to cause movement in the third direction of tissue that is offset from the second virtual extended shear wave source.

44. A system according to claim 43 wherein the means for transmitting the first and second ultrasound energy into the tissue comprises means for transmitting the first and second ultrasound energy into the tissue substantially simultaneously.

45. A system according to claim 44 wherein the first and second virtual extended shear wave sources intersect one another in the tissue.

46. A system according to claim 44 wherein the first and second virtual extended shear wave sources do not intersect one another in the tissue.

47. A system according to claim 34 wherein the virtual extended shear wave comprises a first virtual extended shear wave, the system further comprising:

means for steering the transmitted ultrasound energy into the tissue in a third direction of transmission, that is different than the first, to provide a second virtual extended shear wave source in the tissue.

48. A system according to claim 34 wherein the virtual extended shear wave source comprises a first virtual extended shear wave source, the system further comprising:

means for changing a sub-aperture of an ultrasound transducer array used to transmit the ultrasound energy to provide a second virtual extended shear wave source in the tissue in a third direction.

49. A system according to claim 47 wherein the means for steering comprises means for applying a phased excitation to an ultrasound transducer to steer the transmitted ultrasound energy in the third direction.

50. A system according to claim 47 wherein the means for changing comprises means for changing a location of a sub-aperture of an ultrasound transducer array used to transmit the ultrasound energy.

51. A system according to claim 35 further comprising:

means for determining a displacement map including displacement values associated with respective portions of the tissue subject to the extended shear wave based on the tracking.

52. A system according to claim 34 wherein a length of the virtual extended shear wave source is in a range between about 0.2 mm and about 8.0 cm.

53. A system according to claim 35 wherein the means for tracking comprises means for tracking the movement of the offset tissue in response to the extended shear wave using receive mode parallel processing.

54. A system according to claim 35 wherein the means for transmitting comprises means for transmitting ultrasound energy into tissue using a first modality;

and

wherein the means for tracking comprises means for tracking the movement of the offset tissue in response to the extended shear wave using a second modality.

55. A system according to claim 35 wherein the means for tracking comprises means for tracking in at least one dimension.

56. A system according to claim 34 wherein the means for transmitting comprises means for applying an excitation to an ultrasound transducer used to transmit the ultrasound energy.

57. A system according to claim 34 wherein the means for transmitting comprises means for transmitting unfocused ultrasound energy into the tissue to provide the virtual extended shear wave source.

58. A system according to claim 34 wherein the virtual extended shear wave source further generates a second extended shear wave that propagates opposite the second direction.

59. A system according to claim 34 wherein the transmitted ultrasound energy causes the tissue along the first direction to displace in a range between about 0.1 μ

m and about 300 μ

m.

60. A system for scanning tissue using ultrasound, the system comprising means for transmitting ultrasound energy into tissue in a first direction to provide a virtual extended shear wave source that generates an extended shear wave that propagates in a second direction substantially orthogonal to the first direction to cause movement in the first direction of tissue that is offset from the virtual extended shear wave source in the second direction, wherein ultrasound energy is transmitted at an amplitude sufficient to allow the extended shear wave to be tracked.

61. A system according to claim 60 wherein an associated frequency of the virtual extended shear wave source is a range between about 1 MHz and about 25 MHz.

62. A system for imaging tissue using shear wave ultrasound, the system comprising:

means for tracking tissue to obtain first position data associated with tissue;

means for transmitting ultrasound energy into the tissue in a first direction to provide a virtual extended shear wave source that generates an extended shear wave that propagates in a second direction substantially orthogonal to the first direction to cause movement in the first direction of tissue that is offset from the virtual extended shear wave source in the second direction;

means for tracking the offset tissue to obtain second position data;

means for determining a displacement map based on the first and second position data; and

means for generating an image of the tissue based on the displacement map.

63. A system according to claim 62 wherein the means for tracking comprises means for tracking using receive mode parallel processing.

64. A system according to claim 62 wherein the means for transmitting comprises means for transmitting first ultrasound energy in the first direction to provide a first virtual extended shear wave source that generates a first extended shear wave and the image comprises a first image, the system further comprising:

means for transmitting second ultrasound energy in a third direction, that is different than the first direction, to provide a second virtual extended shear wave source that generates a second extended shear wave that propagate orthogonal to the third direction to cause movement in the third direction of tissue that is offset from the second virtual extended shear wave source; and

means for tracking the second extended shear waves to obtain third position data;

means for determining a second displacement map based on the third position data; and

means for generating a second image of the tissue based on the second displacement map.

65. A computer program product for scanning tissue comprising a computer readable storage medium having computer-readable program code means embodied in said medium, said computer-readable program code means comprising:

computer-readable program code means for transmitting ultrasound energy into tissue in a first direction to provide a virtual extended shear wave source that generates an extended shear wave that propagates in a second direction substantially orthogonal to the first direction to cause movement in the first direction of tissue that is offset from the virtual extended shear wave source in the second direction.

66. A computer program product according to claim 65 further comprising:

computer-readable program code means for means for tracking the movement of the offset tissue in response to the extended shear wave.

67. A computer program product according to claim 65 wherein the extended shear wave causes the second tissue to move opposite the first direction.

68. A computer program product according to claim 65 wherein the ultrasound energy is transmitted by an ultrasound transducer array having an associated focal point, wherein the extended shear wave is located on at least one of a far side and a near side of the focal point relative to the ultrasound transducer array.

69. A computer program product according to claim 65 wherein the virtual extended shear wave source comprises a transmit ultrasound beam having an associated amplitude sufficient to generate a trackable extended shear wave.

70. A computer program product according to claim 65 wherein the virtual extended shear wave source has an associated frequency in a range between about 1 MHz and about 25 MHz.

71. A computer program product according to claim 65 wherein the computer-readable program code means for transmitting comprises:

computer-readable program code means for transmitting ultrasound energy from an ultrasound transducer array having an associated focal point, wherein a portion of the virtual extended shear wave source extends at least a portion of a distance between the ultrasound transducer array and the focal point.

72. A computer program product according to claim 65 wherein the first direction defines a substantially orthogonal angle with an ultrasound transducer array used to transmit the ultrasound energy.

73. A computer program product according to claim 65 wherein the first direction defines less than a substantially orthogonal angle with an ultrasound transducer array used to transmit the ultrasound energy.

74. A computer program product according to claim 65 wherein the computer-readable program code means for transmitting comprises:

computer-readable program code means for transmitting first ultrasound energy in the first direction to provide a first virtual extended shear wave source that generates a first extended shear wave, further comprising;

computer-readable program code means for transmitting second ultrasound energy into the tissue in a third direction to provide a second virtual extended shear wave source, wherein the second virtual extended shear wave source generates a second extended shear wave that propagates substantially orthogonal to the third direction to cause movement in the third direction of tissue that is offset from the second virtual extended shear wave source.

75. A computer program product according to claim 74 wherein the computer-readable program code means for transmitting the first and second ultrasound energy into the tissue comprises computer-readable program code means for transmitting the first and second ultrasound energy into the tissue substantially simultaneously.

76. A computer program product according to claim 75 wherein the first and second virtual extended shear wave sources intersect one another in the tissue.

77. A computer program product according to claim 75 wherein the first and second virtual extended shear wave sources do not intersect one another in the tissue.

78. A computer program product according to claim 65 wherein the virtual extended shear wave comprises a first virtual extended shear wave, further comprising:

computer-readable program code means for steering the transmitted ultrasound energy into the tissue in a third direction of transmission, that is different than the first, to provide a second virtual extended shear wave source in the tissue.

79. A computer program product according to claim 65 wherein the virtual extended shear wave source comprises a first virtual extended shear wave source, further comprising:

computer-readable program code means for changing a sub-aperture of an ultrasound transducer array used to transmit the ultrasound energy to provide a second virtual extended shear wave source in the tissue in a third direction.

80. A computer program product according to claim 78 wherein the computer-readable program code means for steering comprises:

computer-readable program code means for applying a phased excitation to an ultrasound transducer to steer the transmitted ultrasound energy in the third direction.

81. A computer program product according to claim 78 wherein the computer-readable program code means for changing comprises:

computer-readable program code means for changing a location of a sub-aperture of an ultrasound transducer array used to transmit the ultrasound energy.

82. A computer program product according to claim 66 further comprising:

computer-readable program code means for determining a displacement map including displacement values associated with respective portions of the tissue subject to the extended shear wave based on the tracking.

83. A computer program product according to claim 65 wherein a length of the virtual extended shear wave source is in a range between about 0.2 mm and about 8.0 cm.

84. A computer program product according to claim 66 wherein the computer-readable program code means for tracking comprises:

computer-readable program code means for tracking the movement of the offset tissue in response to the extended shear wave using receive mode parallel processing.

85. A computer program product according to claim 66 wherein the computer-readable program code means for transmitting comprises:

computer-readable program code means for transmitting ultrasound energy into tissue using a first modality; and

wherein the computer-readable program code means for tracking comprises computer-readable program code means for tracking the movement of the offset tissue in response to the extended shear wave using a second modality.

86. A computer program product according to claim 66 wherein the computer-readable program code means for tracking comprises:

computer-readable program code means for tracking in at least one dimension.

87. A computer program product according to claim 65 wherein the computer-readable program code means for transmitting comprises:

computer-readable program code means for applying an excitation to an ultrasound transducer used to transmit the ultrasound energy.

88. A computer program product according to claim 65 wherein the computer-readable program code means for transmitting comprises:

computer-readable program code means for transmitting unfocused ultrasound energy into the tissue to provide the virtual extended shear wave source.

89. A computer program product according to claim 65 wherein the virtual extended shear wave source further generates a second extended shear wave that propagates opposite the second direction.

90. A computer program product according to claim 65 wherein the transmitted ultrasound energy causes the tissue along the first direction to displace in a range between about 0.1 μ

m and about 300 μ

m.

91. A computer program product for scanning tissue using ultrasound comprising a computer readable storage medium having computer-readable program code means embodied in said medium, said computer-readable program code means comprising:

computer-readable program code means for transmitting ultrasound energy into tissue in a first direction to provide a virtual extended shear wave source that generates an extended shear wave that propagates in a second direction substantially orthogonal to the first direction to cause movement in the first direction of tissue that is offset from the virtual extended shear wave source in the second direction, wherein ultrasound energy is transmitted at an energy sufficient to allow the extended shear wave to be tracked.

92. A computer program product according to claim 91 wherein an associated frequency of the virtual extended shear wave source is a range between about 1 MHz and about 25 MHz.

93. A computer program product for imaging tissue using shear wave ultrasound comprising a computer readable storage medium having computer-readable program code means embodied in said medium, said computer-readable program code means comprising:

computer-readable program code means for tracking tissue to obtain first position data associated with tissue;

computer-readable program code means for transmitting ultrasound energy into the tissue in a first direction to provide a virtual extended shear wave source that generates an extended shear wave that propagates in a second direction substantially orthogonal to the first direction to cause movement in the first direction of tissue that is offset from the virtual extended shear wave source in the second direction;

computer-readable program code means for tracking the offset tissue to obtain second position data;

determining a displacement map based on the first and second position data; and

computer-readable program code means for generating an image of the tissue based on the displacement map.

94. A computer program product according to claim 93 wherein the computer-readable program code means for tracking comprises computer-readable program code means for tracking using receive mode parallel processing.

95. A computer program product according to claim 93 wherein the computer-readable program code means for transmitting comprises:

computer-readable program code means for transmitting first ultrasound energy in the first direction to provide a first virtual extended shear wave source that generates a first extended shear wave and the image comprises a first image, further comprising;

computer-readable program code means for transmitting second ultrasound energy in a third direction, that is different than the first direction, to provide a second virtual extended shear wave source that generates a second extended shear wave that propagates orthogonal to the third direction to cause movement in the third direction of tissue that is offset from the second virtual extended shear wave source; and

computer-readable program code means for tracking the second extended shear wave to obtain third position data;

computer-readable program code means for determining a second displacement map based on the third position data; and

computer-readable program code means for generating a second image of the tissue based on the second displacement map.