Systems and methods for improving ultrasound image quality by applying weighting factors

• US 9,668,714 B2
• Filed: 03/26/2013
• Issued: 06/06/2017
• Est. Priority Date: 04/14/2010
• Status: Active Grant

• Current Assignee: Maui Imaging, Inc.
• Original Assignee: Maui Imaging, Inc.
• Inventors: Call, Josef R., Specht, Donald F., Brewer, Kenneth D.
• Primary Examiner(s): Fernandez, Katherine
• Assistant Examiner(s): PONTIUS, KEVIN LANE
• Application Number:
  US13/850,823
• Publication Number:
  US 20130253325A1
• Time in Patent Office: 1,533 Days
• Field of Search: None
• CPC Class Codes: A61B 8/145 characterised by scanning multiple planes
• CPC Class Codes: A61B 8/4245 involving determining the position of the probe, e.g. with respect to an external reference frame or to the patient
• CPC Class Codes: A61B 8/4427 Device being portable or laptop-like
• CPC Class Codes: A61B 8/4477 using several separate ultrasound transducers or probes
• CPC Class Codes: A61B 8/4483 characterised by features of the ultrasound transducer
• CPC Class Codes: A61B 8/4488 the transducer being a phased array
• CPC Class Codes: A61B 8/461 Displaying means of special interest
• 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 8/5246 combining images from the same or different imaging techniques, e.g. color Doppler and B-mode
• CPC Class Codes: A61B 8/5253 combining overlapping images, e.g. spatial compounding
• CPC Class Codes: A61B 8/54 Control of the diagnostic device
• CPC Class Codes: G01S 15/8913 using separate transducers for transmission and reception
• CPC Class Codes: G01S 15/8927 using simultaneously or sequentially two or more subarrays or subapertures
• CPC Class Codes: G01S 15/8952 using discrete, multiple frequencies
• CPC Class Codes: G01S 7/52046 Techniques for image enhancement involving transmitter or receiver image enhancement by image data processing G06T5/00
• CPC Class Codes: G01S 7/52063 Sector scan display
• CPC Class Codes: G06N 3/084 Backpropagation, e.g. using gradient descent

Abstract

Systems and methods for improving the quality of ultrasound images made up of a combination of multiple sub-images include giving more weight to sub-image information that is more likely to improve a combined image quality. Weighting factor information may be determined from the geometry (e.g., angle or path length) of a location of one or more specific transducer elements relative to a specific point within a region of interest or a region of an image. In some embodiments, any given pixel (or other discrete region of an image) may be formed by combining received echo data in a manner that gives more weight to data that is likely to improve image quality, and/or discounting or ignoring data that is likely to detract from image quality (e.g., by introducing noise or by increasing point spread).

Claims

1. An ultrasound imaging system, comprising:

a first transmit aperture and a second transmit aperture configured to transmit first and second unfocused circular wave front ultrasound signals into a region of interest;

a first receive aperture configured to receive echoes of the first and second unfocused circular wave front ultrasound signals;

a controller configured to form a first image layer from received echoes of the first unfocused circular wave front ultrasound signal, and configured to form a second image layer from received echoes of the second unfocused circular wave front ultrasound signal;

the controller being further configured to determine a value of a weighting factor by;

determining a first distance from one of the first or second transmit apertures to a point represented by at least one pixel;

determining a second distance from the point to the first receive aperture;

summing the first distance and the second distance to obtain a total path length; and

determining the weighting factor as a mathematical function of the total path length;

the controller being further configured to apply the weighting factor to the at least one pixel of the first image layer to obtain a modified first image layer, and to combine the modified first image layer with the second image layer to form a combined image; and

a display device configured to display the combined image.

2. The system of claim 1, wherein the controller is further configured to apply a weighting factor to at least one pixel of the second image layer to obtain a modified second image layer, and to combine the modified first image layer with the modified second image layer to form a second combined image, and wherein the second combined image is displayed on the display device.

3. The system of claim 1, wherein the controller is further configured to, prior to applying the weighting factor, determine said weighting factor or a different value of the weighting factor as a combined weighting factor formed as a combination of the weighting factor and a second weighting factor obtained by determining an angle between a point represented by the at least one pixel and the first transmit aperture, determine whether the angle exceeds a threshold value, select a first value for the second weighting factor if the angle exceeds the threshold value, or select a second value for the second weighting factor if the angle does not exceed the threshold value.

4. The system of claim 1, wherein the controller is further configured to, prior to applying the weighting factor, determine a value of the weighting factor as a combined weighting factor formed as a combination of the weighting factor and a second weighting factor obtained by determining an angle between a point represented by the at least one pixel and the first receive aperture, determine whether the angle exceeds a threshold value, select a first value for the second weighting factor if the angle exceeds the threshold value, or select a second value for the second weighting factor if the angle does not exceed the threshold value.

5. The system of claim 1, wherein the controller is further configured to, prior to applying the weighting factor, determine a first angle between a point represented by the at least one pixel and the first receive aperture, determine a second angle between a point represented by the at least one pixel and the first transmit aperture, and determine the weighting factor as a combined weighting factor formed as a combination of the weighting factor and a second weighting factor that is determined as a mathematical function of the first angle, the second angle, or both the first angle and the second angle, wherein the mathematical function is selected from the group consisting of a monotonic function, a linear function, a normal distribution, a parabolic function, a geometric function, an exponential function, a Gaussian distribution, and a Kaiser-Bessel distribution.

6. The system of claim 1, wherein the controller is further configured to, prior to applying the weighting factor, determine a value of the weighting factor as a combined weighting factor formed as a combination of the weighting factor and a second weighting factor obtained by evaluating a quality of a point-spread-function of the first transmit aperture and the first receive aperture, determine that a pixel image obtained using the first transmit aperture and the first receive aperture will improve image quality, and assign a non-zero positive value to the second weighting factor.

7. An ultrasound imaging system, comprising:

a first transmit aperture configured to transmit first unfocused circular wave front ultrasound signals at a first frequency into a region of interest, and configured to transmit second unfocused circular wave front ultrasound signals at a second frequency into the region of interest, the first frequency being greater than the second frequency;

a first receive aperture configured to receive echoes of the first and second unfocused circular wave front ultrasound signals;

a controller configured to form a first image layer from received echoes of the first unfocused circular wave front ultrasound signal, and configured to form a second image layer from received echoes of the second unfocused circular wave front ultrasound signal, the controller being further configured to apply a weighting factor to at least one pixel of the first image layer to obtain a modified first image layer, the weighting factor being based on a difference between the first frequency and the second frequency, and the controller being configured to combine the modified first image layer with the second image layer to form a combined image; and

a display device configured to display the combined image.

8. The system of claim 7, wherein the controller is further configured to apply said weighting factor or a different weighting factor to at least one pixel of the second image layer to obtain a modified second image layer, and to combine the modified first image layer with the modified second image layer to form a second combined image, and wherein the second combined image is displayed on the display device.

9. The system of claim 7, wherein the controller is further configured to, prior to applying the weighting factor, determine a value of the weighting factor as a combined weighting factor formed as a combination of the weighting factor and a second weighting factor obtained by determining an angle between a point represented by the at least one pixel and the first transmit aperture, determine whether the angle exceeds a threshold value, select a first value for the second weighting factor if the angle exceeds the threshold value, or select a second value for the second weighting factor if the angle does not exceed the threshold value.

10. The system of claim 7, wherein the controller is further configured to, prior to applying the weighting factor, determine a value of the weighting factor as a combined weighting factor formed as a combination of the weighting factor and a second weighting factor obtained by determining an angle between a point represented by the at least one pixel and the first receive aperture, determine whether the angle exceeds a threshold value, select a first value for the second weighting factor if the angle exceeds the threshold value, or select a second value for the second weighting factor if the angle does not exceed the threshold value.

11. The system of claim 7, wherein the controller is further configured to, prior to applying the weighting factor, determine a first angle between a point represented by the at least one pixel and the first receive aperture, determine a second angle between a point represented by the at least one pixel and the first transmit aperture, and determine the weighting factor as a combined weighting factor formed as a combination of the weighting factor and a second weighting factor that is determined as a mathematical function of the first angle, the second angle, or both the first angle and the second angle, wherein the mathematical function is selected from the group consisting of a monotonic function, a linear function, a normal distribution, a parabolic function, a geometric function, an exponential function, a Gaussian distribution, and a Kaiser-Bessel distribution.

12. The system of claim 7, wherein the controller is further configured to, prior to applying the weighting factor, determine a value of the weighting factor as a combined weighting factor formed as a combination of the weighting factor and a second weighting factor obtained by evaluating a quality of a point-spread-function of the first transmit aperture and the first receive aperture, determine that a pixel image obtained using the first transmit aperture and the first receive aperture will improve image quality, and assign a non-zero positive value to the second weighting factor.