Method and apparatus for processing ultrasound image signals

• US 20070230756A1
• Filed: 02/12/2007
• Published: 10/04/2007
• Est. Priority Date: 02/10/2006
• Status: Active Grant

• Current Assignee: University of British Columbia
• Original Assignee: University of British Columbia
• Inventors: Zahiri-Azar, Reza, Wen, Xu, Lawrence, Peter, Salcudean, Septimiu
• Granted Patent: US 8,029,445 B2
• Time in Patent Office: Days
• US Class Current: 382/128
• CPC Class Codes: G01S 15/8906 Short-range imaging systems; Acoustic microscope systems using pulse-echo techniques
• CPC Class Codes: G01S 15/8995 Combining images from different aspect angles, e.g. spatial compounding
• CPC Class Codes: G01S 7/52034 Data rate converters

Abstract

A method and apparatus for processing ultrasonic image signals is disclosed. The method involves receiving a plurality of input sample values representing reflected sound waves in a ultrasonic system, exponentiating each input sample to produce a plurality of respective exponentiated sample values, conditioning the exponentiated sample values to produce conditioned exponentiated sample values for receipt by an imageformer, and causing the imageformer to produce an image representing the ultrasonic sound waves in response to the conditioned exponentiated sample values.

Claims

1. A method for processing ultrasonic image signals, the method comprising:

receiving a plurality of input sample values representing reflected sound waves in a ultrasonic system;

exponentiating each input sample to produce a plurality of respective exponentiated sample values;

conditioning said exponentiated sample values to produce conditioned exponentiated sample values for receipt by an imageformer; and

causing said imageformer to produce an image representing said ultrasonic sound waves in response to said conditioned exponentiated sample values.

2. The method of claim 1 wherein said exponentiating comprises raising each input sample value to a power greater than or equal to one.

3. The method of claim 1 wherein said exponentiation comprises raising said input sample values to a power of about 2.

4. The method of claim 1 wherein receiving said input sample values comprises receiving a plurality of envelope sample values from an envelope interface, said envelope sample values representing an amplitude envelope of a radio frequency (RF) signal, said RF signal representing the reflected sound waves.

5. The method of claim 1 wherein receiving said plurality of input sample values comprises receiving a plurality of input sample values produced by compounding sample values representing reflected sound waves produced by incident ultrasonic sound waves having at least one of differing focal characteristics and differing beam steering angles.

6. The method of claim 5 wherein contiguous groups of a pre-defined number of input sample values are associated with scan lines and wherein said scan lines define a scan frame representing a spatial ultrasound scan of a material, and further comprising:

receiving a plurality of scan frames representing successive ultrasound scans of said material produced by incident ultrasonic sound waves having at least one of differing focal characteristics and differing beam steering angles; and

wherein causing said imageformer to produce said image further comprises compounding conditioned exponentiated sample values in said plurality of scan frames before causing said imageformer to produce said image.

7. The method of claim 1 wherein said conditioning comprises filtering said exponentiated sample values.

8. The method of claim 7 wherein said filtering comprises median filtering said exponentiated sample values using a one dimensional median filter.

9. The method of claim 8 wherein said reflected ultrasonic sound waves represent a location of an object within a material and wherein said median filtering comprises median filtering said exponentiated sample values using a window having a number of samples selected in proportion to a size of said object.

10. The method of claim 1 wherein contiguous groups of a pre-defined number of input sample values are associated with scan lines and wherein said scan lines define a scan frame representing a spatial ultrasound scan of a material, and wherein said conditioning comprises median filtering said exponentiated sample values in successive groups of at least three adjacent scan lines in said scan frame using a two-dimensional median filter.

11. The method of claim 10 wherein said scan frames represent a location of an object within the material and wherein said median filtering comprises median filtering said exponentiated sample values using a window having a number of samples selected in proportion to a size of said object.

12. The method of claim 1 wherein said conditioning comprises setting exponentiated sample values that meet a criterion to a reference value.

13. The method of claim 12 wherein said setting comprises at least one of:

setting exponentiated samples having a value less than a reference threshold value to a minimum sample value; and

setting exponentiated sample values having a value greater than a maximum threshold value to said maximum threshold value.

14. The method of claim 1 further comprising producing said plurality of input sample values before said exponentiation.

15. The method of claim 14 wherein producing said plurality of input sample values comprises:

receiving a plurality radio frequency (RF) sample values, said RF sample values representing the reflected sound waves;

grouping said RF sample values into groups of RF sample values, each group of RF sample values comprising a plurality of contiguous sample values associated with a respective time segment of said RF sample values; and

finding a norm of each of said group of RF sample values to produce said plurality of input sample values.

16. The method of claim 15 wherein said RF sample values represent a location of an object within a material and wherein said grouping comprises grouping said RF sample values into groups of RF sample values each having a number of samples selected in proportion to a size of said object.

17. The method of claim 15 wherein finding said norm comprises computing a norm for each group of RF sample values according to the relation:

18. The method of claim 15 further comprising applying a window function to said RF sample values in each group of RF sample values.

19. The method of claim 18 wherein finding said norm comprises for each group of RF sample values:

computing a discrete Fourier transform for each group of RF sample values to produce a plurality of frequency component values associated with each said group of RF sample values; and

computing a norm of said plurality of frequency component values associated with each said group of RF samples.

20. The method of claim 19 wherein computing said norm comprises computing a norm according to the relation:

21. The method of claim 19 wherein computing said discrete Fourier transform comprises computing a fast Fourier transform (FFT) for each group of RF sample values.

22. The method of claim 21 further comprising appending zero value samples to each group of RF sample values to cause each said group of RF sample values to include a number or RF sample values required for computation of said fast Fourier transform.

23. The method of claim 19 further comprising setting at least some of said frequency component values to a zero value before computing said norm.

24. The method of claim 14 wherein producing said plurality of input sample values comprises:

receiving a plurality of compressed envelope sample values, said compressed envelope sample values representing a compressed amplitude envelope of a radio frequency (RF) signal, said RF signal representing the reflected sound waves; and

decompressing said compressed envelope sample values to produce said input sample values.

25. The method of claim 24 wherein receiving said plurality of compressed envelope sample values comprises receiving logarithmically compressed sample values.

26. The method of claim 25 wherein said decompressing comprises computing said input sample values according to the relation:

27. The method of claim 14 wherein said imageformer is a first imageformer and wherein producing said plurality of input sample values comprises:

receiving a plurality of brightness-mode (B-mode) sample values, said B-mode sample values being generated by a second imageformer associated with the ultrasound system.

28. The method of claim 27 further comprising decompressing said B-mode sample values to produce said input sample values.

29. The method of claim 28 wherein receiving said plurality of B-mode sample values comprises receiving logarithmically compressed B-mode sample values.

30. The method of claim 29 wherein said decompressing comprises computing said input sample values according to the relation:

31. A method for processing ultrasonic image signals, the method comprising:

receiving a plurality of input sample values representing reflected sound waves in a ultrasonic system;

exponentiating each sample to produce a plurality of respective exponentiated sample values;

conditioning said exponentiated sample values to produce conditioned exponentiated sample values for receipt by an imageformer; and

making said conditioned exponentiated sample values available to said imageformer to produce an image representing said ultrasonic reflections.

32. An apparatus for processing ultrasonic image signals, the apparatus comprising:

means for receiving a plurality of input sample values representing reflected sound waves in a ultrasonic system;

means for exponentiating each input sample to produce a plurality of respective exponentiated sample values;

means for conditioning said exponentiated sample values to produce conditioned exponentiated sample values for receipt by an imageformer; and

means for causing said imageformer to produce an image representing said ultrasonic sound waves in response to said conditioned exponentiated sample values.

33. The apparatus of claim 32 wherein said means for exponentiating comprises means for raising each input sample value to a power greater than or equal to one.

34. The apparatus of claim 32 wherein said means for exponentiation comprises means for raising said input sample values to a power of about 2.

35. The apparatus of claim 32 wherein said means for receiving said input sample values comprises means for receiving a plurality of envelope sample values from an envelope interface, said envelope sample values representing an amplitude envelope of a radio frequency (RF) signal, said RF signal representing the reflected sound waves.

36. The apparatus of claim 32 wherein said means for receiving said plurality of input sample values comprises means for receiving a plurality of input sample values produced by compounding sample values representing reflected sound waves produced by incident ultrasonic sound waves having at least one of differing focal characteristics and differing beam steering angles.

37. The apparatus of claim 36 wherein contiguous groups of a pre-defined number of input sample values are associated with scan lines and wherein said scan lines define a scan frame representing a spatial ultrasound scan of a material, and further comprising:

means for receiving a plurality of scan frames representing successive ultrasound scans of said material produced by incident ultrasonic sound waves having at least one of differing focal characteristics and differing beam steering angles; and

wherein said means for causing said imageformer to produce said image further comprises means for compounding conditioned exponentiated sample values in said plurality of scan frames before causing said imageformer to produce said image.

38. The apparatus of claim 32 wherein said means for conditioning comprises means for filtering said exponentiated sample values.

39. The apparatus of claim 38 wherein said means for filtering comprises means for median filtering said exponentiated sample values using a one dimensional median filter.

40. The apparatus of claim 39 wherein said reflected ultrasonic sound waves represent a location of an object within a material and wherein said means for median filtering comprises means for median filtering said exponentiated sample values using a window having a number of samples selected in proportion to a size of said object.

41. The apparatus of claim 32 wherein contiguous groups of a pre-defined number of input sample values are associated with scan lines and wherein said scan lines define a scan frame representing a spatial ultrasound scan of a material, and wherein said means for conditioning comprises means for median filtering said exponentiated sample values in successive groups of at least three adjacent scan lines in said scan frame using a two-dimensional median filter.

42. The apparatus of claim 41 wherein said scan frames represent a location of an object within the material and wherein said means for median filtering comprises means for median filtering said exponentiated sample values using a window having a number of samples selected in proportion to a size of said object.

43. The apparatus of claim 32 wherein said means for conditioning comprises means for setting exponentiated sample values that meet a criterion to a reference value.

44. The apparatus of claim 43 wherein said means for setting comprises at least one of:

means for setting exponentiated samples having a value less than a reference threshold value to a minimum sample value; and

means for setting exponentiated sample values having a value greater than a maximum threshold value to said maximum threshold value.

45. The apparatus of claim 32 further comprising means for producing said plurality of input sample values before said exponentiation.

46. The apparatus of claim 45 wherein said means for producing said plurality of input sample values comprises:

means for receiving a plurality radio frequency (RF) sample values, said RF sample values representing the reflected sound waves;

means for grouping said RF sample values into groups of RF sample values, each group of RF sample values comprising a plurality of contiguous sample values associated with a respective time segment of said RF sample values; and

means for finding a norm of each of said group of RF sample values to produce said plurality of input sample values.

47. The apparatus of claim 46 wherein said RF sample values represent a location of an object within a material and wherein said means for grouping comprises means for grouping said RF sample values into groups of RF sample values each having a number of samples selected in proportion to a size of said object.

48. The apparatus of claim 46 wherein said means for finding said norm comprises means for computing a norm for each group of RF sample values according to the relation:

49. The apparatus of claim 46 further comprising means for applying a window function to said RF sample values in each group of RF sample values.

50. The apparatus of claim 49 wherein said means for finding said norm comprises for each group of RF sample values:

means for computing a discrete Fourier transform for each group of RF sample values to produce a plurality of frequency component values associated with each said group of RF sample values; and

means for computing a norm of said plurality of frequency component values associated with each said group of RF samples.

51. The apparatus of claim 50 wherein said means for computing said norm comprises means for computing a norm according to the relation:

52. The apparatus of claim 50 wherein computing said discrete Fourier transform comprises means for computing a fast Fourier transform (FFT) for each group of RF sample values.

53. The apparatus of claim 52 further comprising means for appending zero value samples to each group of RF sample values to cause each said group of RF sample values to include a number of RF sample values required for computation of said fast Fourier transform.

54. The apparatus of claim 50 further comprising means for setting at least some of said frequency component values to a zero value before computing said norm.

55. The apparatus of claim 45 wherein said means for producing said plurality of input sample values comprises:

means for receiving a plurality of compressed envelope sample values, said compressed envelope sample values representing a compressed amplitude envelope of a radio frequency (RF) signal, said RF signal representing the reflected sound waves; and

means for decompressing said compressed envelope sample values to produce said input sample values.

56. The apparatus of claim 55 wherein said means for receiving said plurality of compressed envelope sample values comprises means for receiving logarithmically compressed sample values.

57. The apparatus of Claim 56 wherein said means for decompressing comprises means for computing said input sample values according to the relation:

58. The apparatus of claim 45 wherein said imageformer is a first imageformer and wherein said means for producing said plurality of input sample values comprises:

means for receiving a plurality of brightness-mode (B-mode) sample values, said B-mode sample values being generated by a second imageformer associated with the ultrasound system.

59. The apparatus of claim 58 further comprising means for decompressing said B-mode sample values to produce said input sample values.

60. The apparatus of claim 59 wherein said means for receiving said plurality of B-mode sample values comprises means for receiving logarithmically compressed B-mode sample values.

61. The apparatus of claim 60 wherein said means for decompressing comprises means for computing said input sample values according to the relation:

62. An apparatus for processing ultrasonic image signals, the apparatus comprising:

means for receiving a plurality of input sample values representing reflected sound waves in a ultrasonic system;

means for exponentiating each sample to produce a plurality of respective exponentiated sample values;

means for conditioning said exponentiated sample values to produce conditioned exponentiated sample values for receipt by an imageformer; and

means for making said conditioned exponentiated sample values available to said imageformer to produce an image representing said ultrasonic reflections.

63. An apparatus for processing ultrasonic image signals, the apparatus comprising:

a receiver for receiving a plurality of input sample values representing reflected sound waves in a ultrasonic system;

an image enhancer operably configured to;

exponentiate each input sample to produce a plurality of respective exponentiated sample values;

condition said exponentiated sample values to produce conditioned exponentiated sample values for receipt by an imageformer; and

an imageformer operably configured to produce an image representing said ultrasonic sound waves in response to said conditioned exponentiated sample values.

64. The apparatus of claim 63 wherein said image enhancer is operably configured to raise each input sample value to a power greater than or equal to one.

65. The apparatus of claim 63 wherein image enhancer is operably configured to raise said input sample values to a power of about 2.

66. The apparatus of claim 63 further comprising an envelope interface operably configured to produce envelope sample values for receipt by said receiver, said envelope sample values representing an amplitude envelope of a radio frequency (RF) signal, said RF signal representing the reflected sound waves.

67. The apparatus of claim 63 wherein said receiver is operably configured to receive a plurality of input sample values produced by compounding sample values representing reflected sound waves produced by incident ultrasonic sound waves having at least one of differing focal characteristics and differing beam steering angles.

68. The apparatus of claim 67 wherein contiguous groups of a pre-defined number of input sample values are associated with scan lines and wherein said scan lines define a scan frame representing a spatial ultrasound scan of a material, and wherein said receiver is operably configured to receive a plurality of scan frames representing successive ultrasound scans of said material produced by incident ultrasonic sound waves having at least one of differing focal characteristics and differing beam steering angles and wherein said imageformer is operably configured to compound conditioned exponentiated sample values in said plurality of scan frames before causing said imageformer to produce said image.

69. The apparatus of claim 63 wherein said conditioner comprises a filter operably configured to filter said exponentiated sample values.

70. The apparatus of claim 69 wherein said filter comprises a one dimensional median filter.

71. The apparatus of claim 70 wherein said reflected ultrasonic sound waves represent a location of an object within a material and wherein said median filter comprises a window having a number of samples selected in proportion to a size of said object.

72. The apparatus of claim 63 wherein contiguous groups of a pre-defined number of input sample values are associated with scan lines and wherein said scan lines define a scan frame representing a spatial ultrasound scan of a material, and wherein said conditioner comprises a two-dimensional median filter operably configured to filter said exponentiated sample values in successive groups of at least three adjacent scan lines in said scan frame.

73. The apparatus of claim 72 wherein said scan frames represent a location of an object within the material and wherein said median filter comprises a window having a number of samples selected in proportion to a size of said object.

74. The apparatus of claim 63 wherein said conditioner is operably configured to set exponentiated sample values that meet a criterion to a reference value.

75. The apparatus of claim 74 wherein said conditioner is operably configured to set at least one of:

exponentiated samples having a value less than a reference threshold value to a minimum sample value; and

exponentiated sample values having a value greater than a maximum threshold value to said maximum threshold value.

76. The apparatus of claim 63 further comprising an interface operably configured to produce said plurality of input sample values before said exponentiation.

77. The apparatus of claim 76 wherein said interface comprises a radio frequency (RF) interface, said RF interface being operably configured to:

receive a plurality of RF sample values, said RF sample values representing the reflected sound waves,

group said RF sample values into groups of RF sample values, each group of RF sample values comprising a plurality of contiguous sample values associated with a respective time segment of said RF sample values; and

find a norm of each of said group of RF sample values to produce said plurality of input sample values.

78. The apparatus of claim 77 wherein said RF sample values represent a location of an object within a material and wherein said RF interface is operably configured to group said RF sample values into groups of RF sample values each having a number of samples selected in proportion to a size of said object.

79. The apparatus of claim 77 wherein said RF interface is operably configured to compute a norm for each group of RF sample values according to the relation:

80. The apparatus of claim 77 wherein said RF interface is operably configured to apply a window function to said RF sample values in each group of RF sample values.

81. The apparatus of claim 80 wherein the RF interface is operably configured to:

compute a discrete Fourier transform for each group of RF sample values to produce a plurality of frequency component values associated with each said group of RF sample values; and

compute a norm of said plurality of frequency component values associated with each said group of RF samples.

82. The apparatus of claim 81 wherein said RF interface is operably configured to compute said norm according to the relation:

83. The apparatus of claim 81 wherein said RF interface is operably configured to compute a fast Fourier transform (FFT) for each group of RF sample values.

84. The apparatus of claim 83 wherein said RF interface is operably configured to append zero value samples to each group of RF sample values to cause each said group of RF sample values to include a number of RF sample values required for computation of said fast Fourier transform.

85. The apparatus of claim 81 wherein said RF interface is operably configured to set at least some of said frequency component values to a zero value before computing said norm.

86. The apparatus of claim 76 wherein said interface comprises a compression interface operably configured to:

receive a plurality of compressed envelope sample values, said compressed envelope sample values representing a compressed amplitude envelope of a radio frequency (RF) signal, said RF signal representing the reflected sound waves; and

decompress said compressed envelope sample values to produce said input sample values.

87. The apparatus of claim 86 wherein said compression interface is operably configured to receive logarithmically compressed sample values.

88. The apparatus of claim 87 wherein said compression interface is operably configured to compute said input sample values according to the relation:

89. The apparatus of claim 76 wherein said imageformer is a first imageformer and wherein said interface comprises a brightness-mode (B-mode) interface, said B-mode interface being operably configured to receive a plurality of B-mode sample values from the ultrasonic system, said B-mode sample values being generated by a second imageformer associated with said ultrasound system.

90. The apparatus of claim 89 wherein said B-mode interface is operably configured to decompress said B-mode sample values to produce said input sample values.

91. The apparatus of claim 90 wherein said B-mode interface is operably configured to receive logarithmically compressed B-mode sample values.

92. The apparatus of claim 91 wherein said B-mode interface is operably configured to compute said input sample values according to the relation:

93. An apparatus for processing ultrasonic image signals, the apparatus comprising:

a receiver operably configured to receive a plurality of input sample values representing reflected sound waves in a ultrasonic system;

an image enhancer operably configured to;

exponentiate each sample to produce a plurality of respective exponentiated sample values;

condition said exponentiated sample values to produce conditioned exponentiated sample values for receipt by an imageformer; and

make said conditioned exponentiated sample values available to an imageformer to produce an image representing said ultrasonic reflections.

94. A computer readable medium encoded with codes for directing a processor circuit to carry out a method for processing ultrasonic image signals, the method comprising:

receiving a plurality of input sample values representing reflected sound waves in a ultrasonic system;

exponentiating each input sample to produce a plurality of respective exponentiated sample values;

conditioning said exponentiated sample values to produce conditioned exponentiated sample values for receipt by an imageformer; and

causing said imageformer to produce an image representing said ultrasonic sound waves in response to said conditioned exponentiated sample values.

95. A computer readable signal encoded with codes for directing a processor circuit to carry out a method for processing ultrasonic image signals, the method comprising:

receiving a plurality of input sample values representing reflected sound waves in a ultrasonic system;

exponentiating each input sample to produce a plurality of respective exponentiated sample values;

conditioning said exponentiated sample values to produce conditioned exponentiated sample values for receipt by an imageformer; and

causing said imageformer to produce an image representing said ultrasonic sound waves in response to said conditioned exponentiated sample values.