Ultrasound clutter filter

• US 6,689,064 B2
• Filed: 06/22/2001
• Issued: 02/10/2004
• Est. Priority Date: 06/22/2001
• Status: Expired due to Fees

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Thiele, Karl E, Hager, Richard A, Witt, Jerome F, Clark, David W
• Primary Examiner(s): Jaworski, Francis J.
• Assistant Examiner(s): Jung, William C
• Application Number:
  US09/887,648
• Publication Number:
  US 20030069505A1
• Time in Patent Office: 963 Days
• Field of Search: 600/437-472
• US Class Current: 600/454
• CPC Class Codes: G01S 15/8981 Discriminating between fixed and moving objects or between objects moving at different speeds, e.g. wall clutter filter
• CPC Class Codes: G01S 7/52026 Extracting wanted echo signals Doppler systems G01S15/50; Doppler short range imaging systems G01S15/8979

Abstract

A method for adaptive filtering of clutter from a sample stream having a blood signal component and a clutter signal component comprises the steps of (a) estimating a signal strength of the sample stream, and (b) determining an order of a filter based on a relationship between the signal strength estimate and a signal strength threshold. The filter receives the sample stream and provides an output stream having a reduced level of the clutter signal component relative to the blood signal component.

Claims

1. A method for adaptive filtering of clutter from a sample stream having a blood signal component and a clutter signal component, said method comprising:

estimating a signal strength of said sample stream; and

determining an order of an adaptive clutter filter and generating its filter coefficients based on a relationship between said signal strength estimate and a signal strength threshold,

wherein responsive to receiving said sample stream, said adaptive clutter filter provides an output stream having a reduced level of said clutter signal component relative to said blood signal component.

2. A method for adaptive filtering of clutter from a sample stream having a blood signal component and a clutter signal component, said method comprising:

estimating a signal strength and a frequency of said sample stream; and

determining an order of an adaptive clutter filter and generating its filter coefficients based on (a) a relationship between said signal strength estimate and a signal strength threshold, and (b) a relationship between said frequency estimate and a frequency threshold,

wherein responsive to receiving said sample stream, said adaptive clutter filter provides an output stream having a reduced level of said clutter signal component relative to said blood signal component.

3. A method for adaptive filtering of clutter from a sample stream having a blood signal component and a clutter signal component, said method comprising:

estimating a signal strength and a frequency of said sample stream; and

determining a zero of an adaptive clutter filter based on a linear prediction analysis of said sample stream responsive to said signal strength estimate falling within a predetermined range of signal strengths and responsive to said frequency estimate falling within a predetermined range of frequencies,

wherein responsive to receiving said sample stream, said adaptive clutter filter provides an output stream having a reduced level of said clutter signal component relative to said blood signal component.

4. A controller for an adaptive clutter filter for filtering of clutter from a sample stream having a blood signal component and a clutter signal component, comprising:

a module for estimating a signal strength of said sample stream; and

a module for determining an order of said adaptive clutter filter and generating its filter coefficients based on a relationship between said signal strength estimate and a signal strength threshold,

wherein responsive to receiving said sample stream, said adaptive clutter filter provides an output stream having a reduced level of said clutter signal component relative to said blood signal component.

5. The controller of claim 4, wherein said module for determining and generating generates a filter coefficient for said adaptive clutter filter by a linear prediction analysis of said sample stream.

6. The controller of claim 4, further comprising:

a module for estimating a frequency of said sample stream; and

a module for determining a zero for said filter based on said frequency estimate.

7. The controller of claim 6, wherein said module for determining said zero obtains a filter coefficient for said filter from a lookup table.

8. The controller of claim 6, wherein said zero is on a unit circle.

9. A controller for an adaptive clutter filter for filtering of clutter from a sample stream having a blood signal component and a clutter signal component, comprising:

a module for estimating a signal strength and a frequency of said sample stream; and

a module for determining an order of said adaptive clutter filter and generating its filter coefficients based on (a) a relationship between said signal strength estimate and a signal strength threshold, and (b) a relationship between said frequency estimate and a frequency threshold,

wherein responsive to receiving said sample stream, said adaptive clutter filter provides an output stream having a reduced level of said clutter signal component relative to said blood signal component.

10. The controller of claim 9, wherein said module for determining and generating generates a filter coefficient for said adaptive clutter filter by a linear prediction analysis of said sample stream.

11. The controller of claim 9, further comprising a module for determining a zero for said filter based on said frequency estimate.

12. The controller of claim 11, wherein said module for determining said zero obtains a filter coefficient for said filter from a lookup table.

13. The controller of claim 11, wherein said zero is on a unit circle.

14. A controller for an adaptive clutter filter for filtering of clutter from a sample stream having a blood signal component and a clutter signal component, comprising:

a module for estimating a signal strength and a frequency of said sample stream; and

a module for determining a zero of said adaptive clutter filter based on a linear prediction analysis of said sample stream responsive to said signal strength estimate falling within a predetermined range of signal strengths and responsive to said frequency estimate falling within a predetermined range of frequencies,

wherein responsive to receiving said sample stream, said adaptive clutter filter provides an output stream having a reduced level of said clutter signal component relative to said blood signal component.

15. The controller of claim 14, further comprising a module for determining an order of said adaptive clutter filter based on a relationship between said signal strength estimate and a signal strength threshold.

16. The controller of claim 14, further comprising a module for determining an order of said adaptive clutter filter based on a relationship between said frequency estimate and a frequency threshold.

17. An ultrasound clutter filter comprising:

a controller adapted to receive a sample stream having a blood signal component and a clutter signal component, said controller responsive to the sample stream for generating a filter coefficient based on (a) a signal strength threshold, (b) a signal frequency threshold, and (c) said sample stream; and

an adaptive clutter filter adapted to receive said sample stream and said filter coefficient, said adaptive clutter filter having a variable configuration that is defined by said filter coefficient, said variable configuration including (a) a variable order, (b) an adaptive zero and (c) a variable center frequency,

wherein responsive to receiving said sample stream, said adaptive clutter filter provides an output stream having a reduced level of said clutter signal component relative to said blood signal component.

18. The ultrasound clutter filter of claim 17, wherein said controller comprises:

a signal strength estimator for estimating a signal strength of said sample stream;

a signal frequency estimator for estimating a frequency of said sample stream;

a module for defining said variable order based on said signal strength estimate and said frequency estimate; and

a coefficient calculator for producing said filter coefficient based on said signal strength estimate and said frequency estimate.

19. The ultrasound clutter filter of claim 17, wherein said controller determines said filter coefficient by a linear prediction analysis of said sample stream.

20. The ultrasound clutter filter of claim 17, wherein said adaptive zero is on a unit circle.

21. The ultrasound clutter filter of claim 17, wherein said adaptive clutter filter comprises:

a lattice filter for receiving said sample stream and providing an output; and

finite impulse response filter for receiving said output of said lattice filter and for producing said output stream.

22. A storage medium comprising instructions on a computer recordable medium for controlling a processor for adaptive filtering of clutter from a sample stream having a blood signal component and a clutter signal component, including:

instructions for estimating a signal strength of said samples stream; and

instructions for determining an order of an adaptive clutter filter and generating its filter coefficients based on a relationship between said signal strength estimate and a signal strength threshold,

wherein responsive to receiving said sample stream, said adaptive clutter filter provides an output stream having a reduced level of said clutter signal component relative to said blood signal component.

23. A storage medium comprising instructions on a computer recordable medium for controlling a processor for adaptive filtering of clutter from a sample stream having a blood signal component and a clutter signal component, including:

instructions for estimating a signal strength and a frequency of said sample stream; and

instructions for determining an order of an adaptive clutter filter and generating its filter coefficients based on (a) a relationship between said signal strength estimate and a signal strength threshold, and (a) a relationship between said frequency estimate and a frequency threshold,

wherein responsive to receiving said sample stream said adaptive clutter filter provides an output stream having a reduced level of said clutter signal component relative to said blood signal component.

24. A storage medium comprising instructions on a computer recordable medium for controlling a processor for adaptive filtering of clutter from a sample stream having a blood signal component and a clutter signal component, including:

instructions for estimating a signal strength and a frequency of said sample stream; and

instructions for determining a zero of an adaptive clutter filter based on a linear prediction analysis of said sample stream responsive to said signal strength estimate falling within a predetermined range of signal strengths and responsive to said frequency estimate falls within a predetermined range of frequencies,

wherein responsive to receiving said sample stream, said adaptive clutter filter provides an output stream having a reduced level of said clutter signal component relative to said blood signal component.