Method and apparatus for automatic setting of sample gate in pulsed doppler ultrasound imaging

• US 6,322,509 B1
• Filed: 09/07/2000
• Issued: 11/27/2001
• Est. Priority Date: 05/01/2000
• Status: Expired due to Fees

• Current Assignee: GE Medical Systems Global Technology Company LLC (GE Healthcare Technologies, Inc.)
• Original Assignee: GE Medical Systems Global Technology Company LLC (GE Healthcare Technologies, Inc.)
• Inventors: Dong, Fang, Mo, Larry Y. L., Pan, Lihong, Washburn, Michael J.
• Primary Examiner(s): Lateef, Marvin M.
• Assistant Examiner(s): PATEL, MAULIN M
• Application Number:
  US09/656,659
• Time in Patent Office: 446 Days
• Field of Search: 600/443, 600/447, 600/444, 600/449, 600/437, 382/294, 601/7
• US Class Current: 600/443
• CPC Class Codes: A61B 5/1075 for measuring dimensions by non-invasive methods, e.g. for determining thickness of tissue layer A61B8/0858 takes precedence
• 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: G06T 2207/10132 Ultrasound image
• CPC Class Codes: G06T 2207/30068 Mammography; Breast
• CPC Class Codes: G06T 2207/30096 Tumor; Lesion
• CPC Class Codes: G06T 7/0012 Biomedical image inspection
• CPC Class Codes: G06T 7/11 Region-based segmentation
• CPC Class Codes: G06T 7/136 involving thresholding
• CPC Class Codes: G06T 7/155 involving morphological operators
• CPC Class Codes: G06T 7/62 of area, perimeter, diameter or volume

Abstract

A method and an apparatus for automatically initializing and adjusting the Doppler sample gate position and size settings based on actual vessel image data. A vessel segment search method employs an object search technique based solely on geometric and morphological information in a binarized vessel image obtained from either B-mode or color flow image data. The morphologically best or nearest vessel segment within a target search region in the two-dimensional image is found. The sample gate is placed at or near the center of the targeted vessel segment. The sample gate size is adjusted in relation to the vessel size. Then the best available steering angle that minimizes the Doppler angle is selected.

Claims

1. A method of locating a sample gate in a test subject, comprising the steps of:

(a) detecting a predetermined state associated with a sample gate graphic superimposed on an image being displayed;

(b) processing a frame of imaging data from which said image was derived to determine a predetermined point in a vessel segment in said test subject in response to detection of said predetermined state;

(c) moving a sample gate to a predetermined position relative to said predetermined point in response to completion of said processing step; and

(d) superimposing a sample gate graphic at a new position in said image, said new position corresponding to said predetermined position of said sample gate.

2. The method as recited in claim 1, further comprising the steps of:

(d) processing said imaging data to determine a dimension of said vessel segment; and

(e) adjusting a dimension of said sample gate to have a predetermined relationship to said dimension of said vessel segment.

3. The method as recited in claim 2, wherein said dimension represents an internal diameter of said vessel segment.

4. The method as recited in claim 1, wherein said predetermined state comprises activation of said sample gate graphic.

5. The method as recited in claim 1, wherein said predetermined state comprises movement of said sample gate graphic.

6. The method as recited in claim 1, wherein said step (b) comprises the steps of:

defining a search region in said image; and

searching said search region for a continuous object representing a vessel segment having a predetermined morphological characteristic,

wherein said sample gate graphics is placed in predetermined relationship to a center point of said continuous object representing said vessel segment having said predetermined morphological characteristic.

7. The method as recited in claim 6, wherein said searching step comprises the step of binarizing the pixel values within said search region.

8. The method as recited in claim 7, wherein said binarizing step comprises the step of binarizing the pixel values based on a pixel value threshold that is adaptive to local pixel value statistics.

9. The method as recited in claim 7, wherein said binarizing step comprises the step of binarizing the pixel values based on the presence versus absence of color flow information in each pixel.

10. The method as recited in claim 7, wherein said searching step further comprises the step of performing morphological filtering to eliminate structures smaller than a speckle size.

11. The method as recited in claim 10, wherein said searching step further comprises the steps of:

counting the number of continuous objects in said search region;

computing the area of each continuous object; and

rejecting objects having an area lying outside a predetermined range.

12. The method as recited in claim 1, further comprising the steps of:

(d) processing said imaging data to determine an angle of orientation of said vessel segment in said image; and

(e) selecting a beam steering angle from a plurality of predefined beam steering angles which minimizes an angle between said angle of orientation of said vessel segment and said beam steering angle.

13. The method as recited in claim 1, wherein step (b) comprises the step of finding a center of mass of said vessel segment.

14. The method as recited in claim 1, wherein step (b) comprises the step of calculating average values of a boundary of said vessel segment along horizontal and vertical axes.

15. The method as recited in claim 2, wherein said step (e) is based on power Doppler intensity levels acquired for pixels within said vessel segment.

16. A method of sizing a sample gate in a test subject, comprising the steps of:

(a) detecting a predetermined state associated with a sample gate graphic being displayed;

(b) processing a frame of imaging data from which said image was derived to determine a dimension of a vessel segment in said test subject in response to detection of said predetermined state;

(c) adjusting a dimension of said sample gate to have a predetermined relationship to said dimension of said vessel segment in response to completion of said processing step; and

(d) superimposing a sample gate graphic on said image, said sample gate graphic having a dimension corresponding to said adjusted dimension of said sample gate.

17. The method as recited in claim 16, wherein said dimension of said continuous object represents an internal diameter of said vessel segment.

18. A system comprising:

a display device comprising a multiplicity of pixels;

a memory for storing a frame of image pixel values; and

a computer programmed to perform the steps of;

(a) controlling said display device to display an image derived from said frame of image pixel values and a sample gate graphic superimposed on said image;

(b) detecting a predetermined state associated with said sample gate graphic being displayed;

(c) processing said image pixel values to determine a predetermined point in a vessel segment in said test subject in response to detection of said predetermined state;

(d) moving a sample gate to a predetermined position relative to said predetermined point in response to completion of said processing step; and

(e) superimposing a sample gate graphic at a new position in said image, said new position corresponding to said predetermined position of said sample gate.

19. The system as recited in claim 18, wherein said computer is further programmed to perform the following steps:

(f) processing said image pixel values to determine a dimension of said vessel segment; and

(g) adjusting a dimension of said sample gate graphic so that it has a predetermined relationship to said dimension of said vessel segment.

20. The system as recited in claim 19, wherein said dimension represents an internal diameter of said vessel segment.

21. The system as recited in claim 18, wherein said predetermined state comprises activation of said sample gate graphic.

22. The system as recited in claim 18, wherein said predetermined state comprises movement of said sample gate graphic.

23. The system as recited in claim 18, wherein said computer is further programmed to perform the following steps:

defining a search region in said image; and

searching said search region for a continuous object representing a vessel segment having a predetermined morphological characteristic,

wherein said sample gate graphics is placed in predetermined relationship to a center point of said continuous object representing said vessel segment having said predetermined morphological characteristic.

24. The system as recited in claim 23, wherein said searching step comprises the step of binarizing the pixel values within said search region.

25. The system as recited in claim 24, wherein said binarizing step comprises the step of binarizing the pixel values based on a pixel value threshold that is adaptive to local pixel value statistics.

26. The system as recited in claim 24, wherein said binarizing step comprises the step of binarizing the pixel values based on the presence versus absence of color flow information in each pixel.

27. The system as recited in claim 24, wherein said searching step further comprises the step of performing morphological filtering to eliminate structures smaller than a speckle size.

28. The system as recited in claim 27, wherein said searching step further comprises the steps of:

counting the number of continuous objects in said search region;

computing the area of each continuous object; and

rejecting objects having an area lying outside a predetermined range.

29. The system as recited in claim 18, wherein said computer is further programmed to perform the following steps:

(f) processing said imaging data to determine an angle of orientation of said vessel segment; and

(g) selecting a beam steering angle from a plurality of predefined beam steering angles which minimizes an angle between said angle of orientation of said vessel segment and said beam steering angle.

30. The system as recited in claim 18, wherein step (c) comprises the step of finding a center of mass of said vessel segment.

31. The system as recited in claim 18, wherein step (b) comprises the step of calculating average values of a boundary of said vessel segment along horizontal and vertical axes.

32. The system as recited in claim 19, wherein said step (f) is based on power Doppler intensity levels acquired for pixels within said vessel segment.

33. The system as recited in claim 18, further comprising:

an ultrasound transducer array comprising a multiplicity of transducer elements;

a transmit beamformer for pulsing selected transducer elements to transmit a series of ultrasound transmit beams in a scan plane;

a receive beamformer coupled to selected transducer elements of said transducer array for acquiring respective receive signals subsequent to respective beam transmits;

a signal processor for forming vectors of image parameter values from said receive signals; and

a scan converter for converting said vectors into a frame of image pixel values and storing said frame of image pixel values in said memory.

34. A system comprising:

a display device comprising a multiplicity of pixels;

a memory for storing a frame of image pixel values; and

a computer programmed to perform the steps of;

(a) controlling said display device to display an image derived from said frame of image pixel values and a sample gate graphic superimposed on said image;

(b) detecting a predetermined state associated with said sample gate graphic being displayed;

(c) processing said image pixel values to determine a dimension of a vessel segment in said test subject in response to detection of said predetermined state;

(d) adjusting a dimension of said sample gate to have a predetermined relationship to said dimension of said vessel segment in response to completion of said processing step; and

(e) superimposing a sample gate graphic on said image, said sample gate graphic having a dimension corresponding to said adjusted dimension of said sample gate.

35. The system as recited in claim 34, wherein said dimension represents an internal diameter of said vessel segment.

36. A system comprising:

a display device;

a memory for storing a frame of image pixel values;

means for controlling said display device to display an image derived from said frame of image pixel values;

means for controlling said display device to display a sample gate graphic superimposed on said image;

means for detecting a predetermined state associated with said sample gate graphic being displayed;

means for processing said image pixel values to determine a predetermined point in a vessel segment in said test subject in response to detection of said predetermined state;

means for moving a sample gate to a predetermined position relative to said predetermined point in response to completion of said processing step; and

means for controlling said display device to superimpose a sample gate graphic at a new position in said image, said new position corresponding to said predetermined position of said sample gate.

37. The system as recited in claim 36, further comprising:

means for processing said imaging data to determine a dimension of said vessel segment; and

means for adjusting a dimension of said sample gate graphic to have a predetermined relationship to said dimension of said vessel segment.