Systems and Methods for Processing Ultrasound Color Flow Mapping

• US 20150045666A1
• Filed: 08/09/2013
• Published: 02/12/2015
• Est. Priority Date: 08/09/2013
• Status: Active Grant

• Current Assignee: Sonowise, Inc.
• Original Assignee: Sonowise, Inc.
• Inventors: Lin, Shengtz
• Granted Patent: US 9,173,640 B2
• Time in Patent Office: Days
• US Class Current: 600/441
• 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 8/0891 for diagnosis of blood vessels
• CPC Class Codes: A61B 8/461 Displaying means of special interest
• CPC Class Codes: A61B 8/488 involving Doppler signals
• CPC Class Codes: A61B 8/5207 involving processing of raw data to produce diagnostic data, e.g. for generating an image reconstruction G06T11/00
• CPC Class Codes: A61B 8/5223 for extracting a diagnostic or physiological parameter from medical diagnostic data for algorithms to analyse biomedical images G06T7/0012
• CPC Class Codes: G16H 50/30 for calculating health indices; for individual health risk assessment

Abstract

In one aspect, the invention relates to an ultrasound imaging system that includes an ultrasound receiver configured to receive ultrasound signals scattered from a sample in real time; an acoustic beam former; and an ultrasound data demodulation system. In one embodiment, the ultrasound imaging system further includes a processing system configured to process demodulated scan data and perform ultrasound image generation and flow processing and a display configured to show ultrasound image data and blood flow velocity data relative to such image data. Signals that include positive flow information and negative flow information are separated from received signals using phase-filters and analytic signal transforms such that a first and a second autocorrelation signal processing stage is used to generate mean positive flow, mean negative flow, and variance data for such flows.

Claims

1. A method of ultrasound color flow mapping comprising:

separating a positive flow signal and a negative flow signal from ultrasound data using a first pair of Hilbert transforms;

converting the separated positive flow signal and the separated negative flow signal into a positive flow analytic signal and a negative flow analytic signal using a second pair of Hilbert transforms;

autocorrelating the positive flow analytic signal to obtain a mean positive flow velocity;

autocorrelating the negative flow analytic signal to obtain a mean negative flow velocity; and

performing color flow mapping using the mean positive flow velocity and the mean negative flow velocity.

2. The method of claim 1 further comprising determining a flow velocity variance using an autocorrelation process.

3. The method of claim 2 wherein performing color flow mapping further comprises using the flow velocity variance.

4. The method of claim 1 further comprising collecting the ultrasound data using a probe.

5. The method of claim 4 further comprising selecting a data acquisition period during which the ultrasound data is collected by the probe that ranges from about 2 milliseconds to about 32 milliseconds.

6. The method of claim 5 further comprising the step of reducing occurrence of a spectral broadening artifact in response to the selection of the data acquisition period.

7. The method of claim 1 further comprising performing the autocorrelation steps using a time domain presentation of the positive flow analytic signal and the negative flow analytic signal.

8. The method of claim 1 further comprising

applying a first indicia to ultrasound image data corresponding to the mean positive flow;

and

applying a second indicia to ultrasound image data corresponding to the mean negative flow.

9. The method of claim 8 further comprising displaying ultrasound image data and the first indicia and the second indicia overlaid on a B-mode image.

10. The method of claim 8 further comprising assigning a first color code for the mean positive flow, assigning a second color code for the mean negative flow, and assigning a third color code for the flow with both positive and negative flow.

11. The method of claim 1 wherein the ultrasound data comprises one or more RF signals and further comprising

wall filtering the one or more RF signals to remove vessel wall motion;

and

frequency shifting the positive flow analytic signal and the negative flow analytic signal using a mixer.

12. The method of claim 4 further comprising selecting a pulse repetition frequency in the range of from about 1 KHz to about 50 KHz for the probe.

13. The method of claim 1 wherein a phase angle for one Hilbert transform of the first pair is set at about 0 degrees and a phase angle for the other Hilbert transform of the first pair is set at about 90 degrees.

14. A method of ultrasound color flow mapping comprising:

transforming one or more RF signals received from an ultrasound probe into one or more analytic signals using a first Hilbert transform;

frequency shifting the one or more analytic signals to relative to a baseband using a complex mixer;

wall filtering the one or more frequency shifted analytic signals to remove vessel wall motion;

separating a first flow signal from the one or more wall filtered signals such that a first flow signal results;

transforming the first flow signal into an analytic first flow signal using a second Hilbert transform;

autocorrelating the analytic first flow signal to obtain a mean first flow velocity; and

performing color flow mapping using the mean first flow velocity.

15. The method of claim 14 further comprising

separating a second flow signal from the one or more wall filtered signals;

transforming the first second flow signal into an analytic second flow signal using a third Hilbert transform;

autocorrelating the analytic second flow signal to obtain a mean second flow velocity; and

performing color flow mapping using the mean second flow velocity.

16. An ultrasound system comprising

a mixer comprising a mixer input to receive radiofrequency (RF) signals from an ultrasound probe and a mixer output;

a first wall filter comprising a first wall filter output and a first wall filter input in electrical communication with the mixer output;

a second wall filter comprising a second wall filter output and a second wall filter input in electrical communication with the mixer output;

a first Hilbert filter configured to perform a first Hilbert transform on an in-phase signal received from the first wall filter such that a Hilbert transformed in-phase signal results;

a second Hilbert filter configured to perform a second Hilbert transform on a quadrature phase signal received from the second wall filter such that a Hilbert transformed quadrature signal results;

a first summer in electrical communication with one or more of the first and second Hilbert filters, the first summer configured to receive one or more of the Hilbert transformed in-phase signal and the Hilbert transformed quadrature signal, the first summer comprising a first summer input and a first summer output;

a second summer in electrical communication with one or more of the first and second Hilbert filters, the second summer configured to receive one or more of the Hilbert transformed in-phase signal and the Hilbert transformed quadrature signal, the second summer comprising a second summer input and a second summer output;

a first signal processing device comprising a first analytic signal transform in electrical communication with the first summer output; and

a second signal processing device comprising a second analytic signal transform in electrical communication with the second summer output; and

a processing unit configured to perform autocorrelation on analytic signals received from the first and second signal processing devices.

17. The ultrasound system of claim 16 wherein the first analytic signal transform is a first Hilbert transform having a first phase angle and a second Hilbert transform having a second phase angle.

18. The ultrasound system of claim 17 wherein the second analytic signal transform is a third Hilbert transform having a first phase angle and a fourth Hilbert transform having a second phase angle.

19. The ultrasound system of claim 16 further comprising a display, the display configured to receive color flow mode processing data from the processing unit, the processing unit configured to generate a positive mean flow and a negative mean flow in response to performing autocorrelation on the received analytic signals.

20. The ultrasound system of claim 16 wherein one or more of the Hilbert transforms are implemented using a device selected from the group consisting of a FPGA, a circuit, a filter, a finite impulse response (FIR), and an infinite impulse response (IIR) filter.