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