Ultrasonic harmonic signal acquisition

• US 6,516,667 B1
• Filed: 03/07/2000
• Issued: 02/11/2003
• Est. Priority Date: 03/07/2000
• 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: Lam, Yiu-Hung David, Jago, James R., Broad, Ronald W.
• Primary Examiner(s): Williams, Hezron
• Assistant Examiner(s): Miller, Rose M.
• Application Number:
  US09/520,706
• Time in Patent Office: 1,071 Days
• Field of Search: 736/02, 736/24, 736/25, 736/26, 736/27, 736/28, 600/437, 600/440, 600/441, 600/443, 600/447, 600/454, 600/453, 600/458
• US Class Current: 73/602
• CPC Class Codes: A61B 8/481 involving the use of contrast agent, e.g. microbubbles introduced into the bloodstream analysis of echo signal exploiting properties of a contrast enhancer in devices for short-range imaging with acoustic waves G01S7/52039
• CPC Class Codes: G01S 15/8993 Three dimensional imaging systems
• CPC Class Codes: G01S 7/52025 for pulse systems G01S7/52034 takes precedence
• CPC Class Codes: G01S 7/52026 Extracting wanted echo signals Doppler systems G01S15/50; Doppler short range imaging systems G01S15/8979
• CPC Class Codes: G01S 7/52033 Gain control of receivers for seismic signals G01V1/245

Abstract

An ultrasonic diagnostic imaging system receives echo signals from a transducer for digital processing and image formation. An analog to digital converter converts the analog echo signals to digital signal samples. The dynamic range of the analog to digital converter is more efficiently used for harmonic imaging and saturation of the analog to digital converter is more effectively prevented by attenuating the fundamental signal content of echo signals prior to analog to digital conversion.

Claims

1. An ultrasonic diagnostic imaging system comprising:

a transducer which receives ultrasonic echo signals containing fundamental and harmonic signal components;

a frequency sensitive circuit, coupled to receive echo signals produced by said transducer, which passes harmonic frequency signal components relative to fundamental frequency signal components;

an analog to digital converter coupled to receive echo signals processed by said frequency sensitive circuit; and

a digital beamformer coupled to receive digital echo signals produced by said analog to digital converter.

2. The ultrasonic diagnostic imaging system of claim 1, wherein said frequency sensitive circuit comprises an attenuating circuit that exhibits a passband which attenuates fundamental signal components relative to harmonic signal components.

3. The ultrasonic diagnostic imaging system of claim 2, wherein said passband exhibits a lower corner frequency which is above a given fundamental signal frequency and below the second harmonic of said given fundamental signal frequency.

4. The ultrasonic diagnostic imaging system of claim 3, wherein said fundamental signal components occupy a fundamental signal passband and said harmonic signal components occupy a harmonic signal passband;

and

wherein said corner frequency is above the center frequency of said fundamental signal passband and below the center frequency of said harmonic signal passband.

5. The ultrasonic diagnostic imaging system of claim 1, wherein said frequency sensitive circuit comprises a highpass filter.

6. The ultrasonic diagnostic imaging system of claim 5, wherein said highpass filter exhibits a passband having a lower corner frequency which is above a given fundamental signal frequency and below the second harmonic of said given fundamental signal frequency.

7. The ultrasonic diagnostic imaging system of claim 1, wherein said frequency sensitive circuit comprises a bandpass filter.

8. The ultrasonic diagnostic imaging system of claim 7, wherein said bandpass filter exhibits a passband having a lower corner frequency which is above a given fundamental signal frequency and below the second harmonic of said given fundamental signal frequency, and said passband includes said second harmonic frequency.

9. The ultrasonic diagnostic imaging system of claim 1,

wherein the transducer further comprises an array transducer having a plurality of transducer elements which receive ultrasonic echo signals containing fundamental and harmonic signal components;

wherein the digital beamformer further comprises a digital beamformer having a plurality of processing channels coupled to receive ultrasonic echo signals from respective ones of said transducer elements;

wherein the analog to digital converter further comprises a plurality of analog to digital converters having outputs coupled to respective ones of said digital beamformer processing channels; and

wherein the frequency sensitive circuit further comprises a plurality of attenuating circuits coupled between said transducer elements and said analog to digital converters which attenuate fundamental signal components to a greater degree than harmonic signal components.

10. The ultrasonic-diagnostic imaging system of claim 9, wherein said attenuating circuits comprise highpass filters.

11. The ultrasonic diagnostic imaging system of claim 9, wherein said attenuating circuits comprise bandpass filters.

12. The ultrasonic diagnostic imaging system of claim 1,

wherein the frequency sensitive circuit further comprises a circuit, coupled to receive echo signals produced by said transducer, which enhances harmonic signal components relative to fundamental frequency signal components.

13. The ultrasonic diagnostic imaging system of claim 12, wherein the frequency sensitivity of said frequency sensitive circuit is programmable.

14. An ultrasonic diagnostic imaging system comprising:

a transducer which receives ultrasonic echo signals containing fundamental and harmonic signal components;

a frequency sensitive circuit, coupled to receive echo signals produced by said transducer, which passes harmonic frequency signal components relative to fundamental frequency signal components;

an analog to digital converter coupled to receive echo signals processed by said frequency sensitive circuit; and

digital echo signal processor coupled to receive digital echo signals produced by said analog to digital converter;

wherein the frequency sensitive circuit further comprises a circuit, coupled to receive echo signals produced by said transducer, which enhances harmonic signal components relative to fundamental frequency signal components;

wherein the digital echo signal processor further comprises a digital beamformer coupled to receive digital echo signals produced by said analog to digital converter;

wherein said analog to digital converter is operated at a sampling frequency; and

further comprising a second frequency sensitive circuit, coupled between said transducer and said analog to digital converter, which attenuates signals at said sampling frequency.

15. The ultrasonic diagnostic imaging system of claim 14, wherein said first frequency sensitive circuit comprises a filter circuit having a maximum response above a fundamental frequency;

and

wherein said second frequency sensitive circuit comprises an anti-aliasing filter.

16. An ultrasonic diagnostic imaging system comprising:

a transducer which receives ultrasonic echo signals containing fundamental and harmonic signal components;

a frequency sensitive circuit, coupled to receive echo signals produced by said transducer, which passes harmonic frequency signal components relative to fundamental frequency signal components;

an analog to digital converter coupled to receive echo signals processed by said frequency sensitive circuit; and

a digital echo signal processor coupled to receive digital echo signals produced by said analog to digital converter;

wherein the frequency sensitive circuit further comprises a circuit, coupled to receive echo signals produced by said transducer, which enhances harmonic signal components relative to fundamental frequency signal components;

wherein the digital echo signal processor further comprises a digital beamformer coupled to receive digital echo signals produced by said analog to digital converter;

wherein said frequency sensitive circuit comprises a plurality of selectable circuits of different frequency sensitivity.

17. An ultrasonic diagnostic imaging system comprising:

a transducer which receives ultrasonic echo signals containing fundamental and harmonic signal components;

a frequency sensitive circuit, coupled to receive echo signals produced by said transducer, which passes harmonic frequency signal components relative to fundamental frequency signal components;

an analog to digital converter coupled to receive echo signals processed by said frequency sensitive circuit; and

a digital echo signal processor coupled to receive digital echo signals produced by said analog to digital converter;

wherein the transducer comprises a transducer which receives ultrasonic echo signals containing fundamental and harmonic signal components at given frequencies;

wherein the frequency circuit further comprises a plurality of tuned circuits, coupled to receive said echo signals, which are tuned to pass harmonic signals of different frequencies;

wherein the analog to digital converter is coupled to receive echo signals passed by said tuned circuits;

further comprising a tuned circuit selector, coupled to said tuned circuits, which selectively enables passage of harmonic signals by one of said tuned circuits to said analog to digital converter; and

wherein the digital echo signal processor further comprises a digital beamformer coupled to receive digital echo signals produced by said analog to digital converter.

18. The ultrasonic diagnostic imaging system of claim 17, wherein said tuned circuit selector comprises a multiplexer.

19. The ultrasonic diagnostic imaging system of claim 17, wherein said transducer exhibits a nominal operating frequency;

and

wherein said tuned circuit selector acts to enable passage of harmonic signals in correspondence with said nominal operating frequency.

20. The ultrasonic diagnostic imaging system of claim 17, wherein said tuned circuit selector acts to enable passage of harmonic signals in correspondence with depth dependent attenuation effects.

21. The ultrasonic diagnostic imaging system of claim 17, wherein said tuned circuit control acts to enable passage of harmonic signals by said variable tuned circuit in correspondence with depth dependent attenuation effects.

22. An ultrasonic diagnostic imaging system comprising:

a transducer which receives ultrasonic echo signals containing fundamental and harmonic signal components;

a frequency sensitive circuit, coupled to receive echo signals produced by said transducer, which passes harmonic frequency signal components relative to fundamental frequency signal components;

an analog to digital converter coupled-to receive echo signals processed by said frequency sensitive circuit; and

a digital echo signal processor coupled to receive digital echo signals produced by said analog to digital converter;

wherein the transducer further comprises a transducer which receives ultrasonic echo signals containing fundamental and harmonic signal components at given frequencies;

wherein the frequency sensitive circuit further comprises a variable tuned circuit, coupled to receive said echo signals, which is variably tuned to pass harmonic signals relative to corresponding fundamental frequencies;

wherein the analog to digital converter is coupled to receive echo signals passed by said variable tuned circuit;

further comprising a tuned circuit control, coupled to said variable tuned circuit, which selectively tunes said variable tuned circuit to pass harmonic signals of a desired frequency; and

wherein the digital echo signal processor further comprises a digital beamformer coupled to receive digital echo signals produced by said analog to digital converter.

23. The ultrasonic diagnostic imaging system of claim 22, wherein said variable tuned circuit comprises one or more variable resistive or reactive components coupled to said tuned circuit control.