Ultrasonic signal processor for power doppler imaging in a hand held ultrasonic diagnostic instrument

• US 6,383,139 B1
• Filed: 10/22/1999
• Issued: 05/07/2002
• Est. Priority Date: 06/28/1996
• Status: Expired due to Term

• Current Assignee: FUJIFILM SonoSite, Inc. (Fujifilm Holdings Corporation)
• Original Assignee: Sonosite Incorporated (Fujifilm Holdings Corporation)
• Inventors: Pflugrath, Lauren S., Doherty, Terrence R., Pailoor, Ramachandra, Hwang, Juin-Jet, Jones, Geoffrey Hugh
• Primary Examiner(s): Lateef, Marvin M.
• Assistant Examiner(s): Imam, Ali M
• Application Number:
  US09/426,088
• Time in Patent Office: 928 Days
• Field of Search: 600/437, 600/440-443, 600/447, 600/454-456, 600/446, 367/7, 367/11, 367/130, 367/138, 736/25, 736/26, 382/131, 382/181, 395/127
• US Class Current: 600/441
• CPC Class Codes: A61B 2560/0456 Apparatus provided with a docking unit
• CPC Class Codes: A61B 8/00 Diagnosis using ultrasonic, sonic or infrasonic waves imaging of objects using sonar G01S15/00
• CPC Class Codes: A61B 8/06 Measuring blood flow measuring volume flow in general G01F, e.g. G01F1/66, G01F1/72; measuring speed of fluids in general G01P5/00
• CPC Class Codes: A61B 8/13 Tomography A61B8/10, A61B8/12 take precedence; tomography for radiation diagnosis A61B6/02
• CPC Class Codes: A61B 8/14 Echo-tomography
• CPC Class Codes: A61B 8/4427 Device being portable or laptop-like
• CPC Class Codes: A61B 8/4455 Features of the external shape of the probe, e.g. ergonomic aspects
• CPC Class Codes: A61B 8/488 involving Doppler signals
• CPC Class Codes: G01S 15/8915 using a transducer array
• CPC Class Codes: G01S 15/892 the array being curvilinear
• CPC Class Codes: G01S 15/8979 Combined Doppler and pulse-echo imaging systems
• CPC Class Codes: G01S 15/899 Combination of imaging systems with ancillary equipment
• CPC Class Codes: G01S 7/52028 using digital techniques
• CPC Class Codes: G01S 7/52034 Data rate converters
• CPC Class Codes: G01S 7/5206 Two-dimensional coordinated display of distance and direction; B-scan display
• CPC Class Codes: G01S 7/52079 Constructional features constructional features of transducers B06B; mounting transducers G10K11/00; constructional features of ultrasonic medical diagnostic devices A61B8/44
• CPC Class Codes: G01S 7/5208 with integration of processing functions inside probe or scanhead
• CPC Class Codes: G10K 11/004 Mounting transducers, e.g. provided with mechanical moving or orienting device mountings specially adapted to a particular sound-producing device, see the preceding groups G10K1/00 - G10K9/00, e.g. G10K1/26, G10K1/28, G10K9/22; arrangements of sonic watch equipment on submarines B63G8/39; buoys B63B22/00
• CPC Class Codes: G10K 11/345 using energy switching from one active element to another

Abstract

A hand held ultrasonic instrument is provided in a portable unit which performs both B mode and Doppler imaging. The instrument includes a transducer array mounted in a hand-held enclosure, with an integrated circuit transceiver connected to the elements of the array for the reception of echo signals. A digital signal processing circuit performs both B mode and Doppler signal processing such as filtering including wall filtering matrix and Hartley transform matrix functions, detection and Doppler estimation, as well as advanced functions such as assembly of multiple zone focused scanlines, synthetic aperture formation, depth dependent filtering, speckle reduction, flash suppression, and frame averaging. The advent of color flow imaging based on Doppler frequency estimation in medical ultrasound addresses a need for rapid assessment of overall flow characteristics in cardiac care. Typical prior art implementation utilize a high degree of temporal filtering in order to enhance the flow signal, but makes the image slow to respond to changes in flow. This is true of both directional and non-directional implementations, and is necessitated by the instability of traditional estimation techniques that are derived from older color flow techniques. A significant advantage of the present invention is excellent stability of both power and direction estimates.

Claims

1. In an ultrasound device, a digital signal processor comprising:

a digital B mode filter for filtering B mode signals;

a digital Doppler filter for filtering Doppler signals including wall filtering and Hartley transform matrix functions to obtain a Fourier power spectrum,

a B mode signal detection and mapping circuit; and

a Doppler signal estimator circuit using the Fourier power spectrum.

2. The digital signal processor of claim 1, wherein said digital filters, said B mode signal detection and mapping circuit, and said Doppler signal estimator circuit are located on a digital signal processing integrated circuit chip.

3. The digital signal processor of claim 1, wherein common elements of said digital signal processor are used for Doppler processing of Doppler signals, and also for B mode processing of B mode signals.

4. The digital signal processor of claim 3, wherein said common elements include elements of said digital filter circuits.

5. The digital signal processor of claim 4, wherein said digital signal processor includes a digital filter which is operated as a bandpass filter for B mode signals, and as a high pass filter for Doppler signals.

6. The digital signal processor of claim 4, wherein said digital signal processor includes a digital filter which is operated as a bandpass filter for B mode signals and as a wall filter for Doppler signals.

7. The digital signal processor of claim 1, wherein said digital signal processor further includes a normalization circuit for normalizing variations in the transducer aperture.

8. The digital signal processor of claim 1, wherein said digital signal processor further includes means for forming a synthetic aperture.

9. The digital signal processor of claim 1, wherein said digital signal processor further includes a depth dependent filter.

10. The digital signal processor of claim 1, wherein said digital signal processor further includes a speckle reduction circuit.

11. The digital signal processor of claim 1, wherein said digital signal processor further includes a flash suppression circuit for Doppler signals.

12. The digital signal processor of claim 1, wherein said digital signal processor further includes means for assembling scanlines from multiple focal zones.

13. The digital signal processor as defined by claim 1 wherein the Hartley transform matrix functions are implemented in two matrices for in-phase and quadrature signals.

14. The digital signal processor as defined by claim 1 wherein said processor comprises an application specific integrated circuit.

15. The digital signal processor as defined by claim 1 wherein flow direction and power are calculated simultaneously.

16. The digital signal processor as defined by claim 1 wherein directional Doppler information is computed via matrix filtering.

17. The digital signal processor as defined by claim 16 wherein directional Doppler information is displayed without temporal frame averaging.

18. The digital signal processor as defined by claim 16 wherein power Doppler information is displayed without temporal frame averaging.

19. The digital signal processor as defined by claim 1 wherein power Doppler information is computed via matrix filtering.

20. In an ultrasound device, a digital signal processor comprising:

a digital B mode filter for filtering B mode signals;

a digital Doppler filter for filtering Doppler signals including wall filtering and Hartley transform matrix functions to obtain a Fourier power spectrum,

a B mode signal detection and mapping circuit;

a Doppler signal estimator circuit using the Fourier power spectrum,

wherein power Doppler information is computed in cardiac applications via matrix filtering without temporal frame averaging.

21. In an ultrasound device, a digital signal processor comprising:

a digital B mode filter for filtering B mode signals;

a digital Doppler filter for filtering Doppler signals including wall filtering and Hartley transform matrix functions to obtain a Fourier power spectrum, wherein the Hartley transform matrix functions are implemented in two matrices for in-phase and quadrature signals, the output from the in-phase matrix is operated on by a processing unit to provide total Doppler power and the output from the quadrature matrix is operated on by a processing unit to obtain mean frequency and peak frequency from the Fourier power spectrum;

a B mode signal detection and mapping circuit; and

a Doppler signal estimator circuit using the Fourier power spectrum.

22. The digital signal processor as defined by claim 21 wherein each matrix is implemented by passing an input signal sample through a FIR filter to summing and multiplication stages with registers connected thereto for receiving processed values and producing the Doppler power of each sample.

23. The digital signal processor as defined by claim 22 wherein filtering coefficients are defined according to:

$\stackrel{v}{H}=M_h<br><br>\stackrel{\mathrm{<br><br>}}{y}=M_h<br><br>M_f<br><br>\stackrel{\mathrm{<br><br>}}{z}=M_h<br><br>M_f<br><br>\left(\stackrel{\mathrm{<br><br>}}{s}+j<br><br>\text{\hspace{1em}<br><br>}<br><br>\stackrel{\stackrel{\perp <br><br>}{^}}{s}\right)=M_{\mathrm{eh}}<br><br>\left(\stackrel{\mathrm{<br><br>}}{s}+j<br><br>\text{\hspace{1em}<br><br>}<br><br>\stackrel{\stackrel{\perp <br><br>}{^}}{s}\right)$

where the Discrete Hartley Transformation matrix is M_h,

the Hartley transformation of the analytic signal is , and

24. The digital signal processor as defined by claim 23 wherein the digital Doppler filter further includes an accumulator for providing Doppler power for use in color power Doppler and a multiply accumulator for providing mean frequency for use in color flow.

25. The digital signal processor of claim 24 wherein flow direction and power are calculated simultaneously.

26. The digital signal processor as defined by claim 25 wherein said processor comprises an application specific integrated circuit.

27. The digital signal processor as defined by claim 25 wherein display of directional power Doppler information requires no temporal frame averaging.

28. The digital signal processor as defined by claim 25 wherein display of power Doppler information is computed by matrix filtering with no temporal frame averaging.

29. A digital signal processor for a hand-held ultrasonic device comprising:

a digital B mode filter for filtering B mode signals;

a digital Doppler filter for filtering Doppler signals including wall filtering and Hartley transform matrix functions to obtain a Fourier power spectrum,

a B mode signal detection and mapping circuit; and

a Doppler signal estimator circuit using the Fourier power spectrum.

30. The digital signal processor of claim 29, wherein said digital filters, said B mode signal detection and mapping circuit, and said Doppler signal estimator circuit are located on a digital signal processing integrated circuit chip.

31. The digital signal processor of claim 29, wherein common elements of said digital signal processor are used for Doppler processing of Doppler signals, and also for B mode processing of B mode signals.

32. The digital signal processor of claim 31, wherein said common elements include elements of said digital filter circuits.

33. The digital signal processor of claim 32, wherein said digital signal processor includes a digital filter which is operated as a bandpass filter for B mode signals, and as a high pass filter for Doppler signals.

34. The digital signal processor of claim 32, wherein said digital signal processor includes a digital filter which is operated as a bandpass filter for B mode signals and as a wall filter for Doppler signals.

35. The digital signal processor of claim 29, wherein said digital signal processor further includes a normalization circuit for normalizing variations in the transducer aperture.

36. The digital signal processor of claim 29, wherein said digital signal processor further includes means for forming a synthetic aperture.

37. The digital signal processor of claim 29, wherein said digital signal processor further includes a depth dependent filter.

38. The digital signal processor of claim 29, wherein said digital signal processor further includes a speckle reduction circuit.

39. The digital signal processor of claim 29, wherein said digital signal processor further includes a flash suppression circuit for Doppler signals.

40. The digital signal processor of claim 29, wherein said digital signal processor further includes means for assembling scanlines from multiple focal zones.

41. The digital signal processor as defined by claim 29, wherein the Hartley transform matrix functions are implemented in two matrices for in-phase and quadrature signals.

42. The digital signal processor as defined by claim 29, wherein said processor comprises an application specific integrated circuit.

43. The digital signal processor as defined by claim 29, wherein flow direction and power are calculated simultaneously.

44. The digital signal processor as defined by claim 29, wherein directional Doppler information is computed via matrix filtering.

45. The digital signal processor as defined by claim 44, wherein directional Doppler information is displayed without temporal frame averaging.

46. The digital signal processor as defined by claim 29, wherein power Doppler information is computed via matrix filtering.

47. The digital signal processor as defined by claim 44, wherein power Doppler information is displayed without temporal frame averaging.