Contrast imaging method, system and storage medium based on adjusting the plane wave emission angle

Abstract

The present invention discloses an angiography method based on adjusting the number of plane wave emission angles, comprising: receiving echo data in a scanning section, calculating the blood flow velocity of angiography imaging according to the echo data, and indexing a pre-stored association relationship to obtain an optimal number of plane wave emission angles corresponding to the scanning depth and blood flow velocity information of the scanning section; emitting a plane wave at the optimal number of emission angles, and compounding the reflected echo data to generate an image; wherein the pre-stored association relationship is: in a simulated environment, determining the optimal number of plane wave emission angles for achieving the highest contrast-to-noise ratio for each blood flow velocity at each scanning depth, thereby improving the image quality of plane wave angiography.

Description

Technical Field

[0001] The present invention relates to the technical field of medical ultrasound contrast imaging, and in particular to a contrast imaging method, system and storage medium based on adjusting the plane wave emission angle. Background Art

[0002] Plane wave angiography is currently widely used in superficial imaging, with the characteristics of high frame rate and less microbubble crushing. When using plane wave angiography, in order to improve the resolution and image contrast to noise ratio (Contrast to Noise Ratio, CNR), the method of multi-angle transmission of plane waves and compounding the received signals at each angle is often used.

[0003] Increasing the number of emission angles will improve the image contrast to noise ratio (CNR), but when imaging some blood flows with higher flow rates, too many angles will deteriorate the correlation between the data at each angle used to composite a plane wave angiography image, resulting in a weaker composite signal, lower CNR, and worse image quality. Summary of the invention

[0004] The object of the present invention is to provide a radiographic imaging method, system and storage medium based on adjusting the plane wave emission angle.

[0005] In order to achieve the above-mentioned purpose of the invention, the present invention provides a method for adjusting the number of plane wave emission angles, the method comprising the steps of: receiving echo data within a scanning slice surface, calculating the blood flow velocity of angiography imaging based on the echo data, and indexing a pre-stored association relationship to obtain an optimal number of plane wave emission angles corresponding to the scanning depth and blood flow velocity information of the scanning slice; emitting a plane wave at the optimal number of emission angles, and compounding the reflected echo data to generate an image; wherein the pre-stored association relationship is: in a simulated environment, determining the optimal number of plane wave emission angles for achieving the highest contrast-to-noise ratio for each blood flow velocity at each scanning depth.

[0006] As a further improvement of the present invention, the method also includes: obtaining the maximum blood flow velocity and the average blood flow velocity of the echo data; if the difference between the maximum blood flow velocity and the average blood flow velocity is less than a preset threshold, the maximum blood flow velocity is used as the blood flow velocity for calculating the angiographic imaging to obtain the optimal number of plane wave emission angles.

[0007] As a further improvement of the present invention, the method also includes: if the difference between the maximum blood flow velocity and the average blood flow velocity is greater than or equal to a preset threshold, the average blood flow velocity is used as the blood flow velocity for calculating angiography to obtain the optimal number of plane wave emission angles.

[0008] As a further improvement of the present invention, the method also includes: emitting a plane wave at the optimal number of plane wave emission angles M, and compounding the M reflected echo data to generate a first frame of image; obtaining the corresponding optimal number of plane wave emission angles N at the maximum blood flow velocity; selecting the middle symmetrical N echo data from the M reflected echo data for compounding to generate a second frame of image; and compounding the first frame of image and the second frame of image to generate an image.

[0009] As a further improvement of the present invention, the method further includes: in the simulation environment, the echo data of the transmitted plane wave includes noise data outside the tube and microbubble data inside the tube.

[0010] As a further improvement of the present invention, the method includes: arbitrarily selecting in-tube microbubble data and out-tube noise data with the same area and scanning depth from the echo data of the emitted plane wave; calculating the ratio of the in-tube microbubble data to the out-tube noise data to obtain the contrast-to-noise ratio of the echo data.

[0011] As a further improvement of the present invention, the method further includes: calculating the contrast-to-noise ratio for each scanning depth, each blood flow velocity, and each plane wave emission angle number are all within a preset range.

[0012] As a further improvement of the present invention, the "calculating the blood flow velocity of contrast imaging based on the echo data" specifically includes: adjusting the plane wave deflection angle in sequence according to preset angles, and obtaining echo data at each deflection angle; performing beam synthesis on the echo data, and calculating the I / Q data at two adjacent deflection angles using the Doppler frequency shift method; and obtaining the blood flow velocity at each sampling point in the echo data based on the I / Q data.

[0013] The present invention also provides an angiography system based on adjusting the plane wave emission angle, the system comprising: a pre-stored association module, a plane wave echo receiving module, a blood flow velocity processing module, an image processing module, and an image output module. The system is used to execute any one of the above-mentioned angiography methods based on adjusting the plane wave emission angle.

[0014] The present invention also provides a storage medium storing a computer program, wherein the computer program, when executed by a processor, implements any of the above-mentioned contrast imaging methods based on adjusting the plane wave emission angle.

[0015] Compared with the prior art, the present invention provides a method for contrast imaging based on adjusting the number of plane wave emission angles, calculates the blood flow velocity of contrast imaging based on the echo data of the received scanning section, and then obtains the optimal number of plane wave emission angles corresponding to the scanning depth and blood flow velocity information of the scanning section based on the pre-stored association relationship obtained in a simulated environment; dynamically adjusts the emission parameters of the plane wave according to the optimal number of plane wave emission angles, realizes adaptive optimization of the number of plane wave emission angles, and improves the flexibility of emission; emits the plane wave at the optimal number of emission angles, and composites the emitted echo data to generate an image, thereby improving the quality of the image. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a flow chart of a contrast imaging method based on adjusting the plane wave emission angle in an embodiment of the present invention.

[0017] Figure 2 Schematic diagram of microbubble data inside the tube and noise data outside the tube in echo data in an embodiment of the present invention.

[0018] Figure 3a It is a schematic diagram of the contrast-to-noise ratio of different blood flow velocities at different depths and different emission angles in an embodiment of the present invention.

[0019] Figure 3b It is a schematic diagram of the contrast-to-noise ratio at different depths, different blood flow velocities, different emission angles and different emission ranges in an embodiment of the present invention.

[0020] Figure 4 Schematic diagram of the relationship between the contrast-to-noise ratio and the angle number at the same depth and the same blood flow velocity in an embodiment of the present invention.

[0021] Figure 5 Schematic diagram of the relationship between blood flow velocity and cumulative density in the area to be scanned in an embodiment of the present invention.

[0022] Figure 6 It is a flow chart of a contrast imaging method based on adjusting the plane wave emission angle in an embodiment of the present invention. DETAILED DESCRIPTION

[0023] The present invention will be described in detail below in conjunction with the specific embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and any structural, methodological, or functional changes made by a person skilled in the art based on these embodiments are all within the scope of protection of the present invention.

[0024] It should be noted that the term "comprises" or any other variation thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In addition, the terms "first", "second", etc. are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0025] The present application discloses a method for contrast imaging based on adjusting the plane wave emission angle in one embodiment. Although the present application provides the following embodiments or processes: Figure 1 The method operation steps described are based on routine or no creative labor, and the steps of the method do not have a necessary causal relationship in logic. The execution order of these steps is not limited to the execution order provided in the implementation mode of this application. Figure 1 As shown, an embodiment of the present invention provides a method for contrast imaging based on adjusting the plane wave emission angle, the method comprising the following steps, the method and each step are described below:

[0026] Step 101, acquiring multiple sets of plane wave echo data in a simulation environment;

[0027] The simulation environment is a model environment that imitates human tissue, such as a blood flow model that imitates human vascular tissue. The blood flow model is scanned, and multiple deflection angles of plane wave emission are obtained according to a preset plane wave emission angle range and a number of emission angles, wherein the preset plane wave emission angle range is generally symmetrically distributed with 0° as the center point, such as [-15°, 15°]. According to the multiple deflection angles, the transmitting end is controlled to emit a plane wave to the area to be scanned in the simulation environment according to the multiple deflection angles to obtain multiple echo signals, and the multiple echo signals are composited to generate a frame of plane wave echo data, wherein the plane wave emission angle exists within the preset angle range and is evenly distributed within the preset angle range. If there are multiple sets of emission angles, multiple sets of plane wave echo data will be generated.

[0028] In a specific embodiment, the preset angle range is [-10°, 10°], the preset angle number is 5, and the corresponding plane wave transmission angle value can be calculated according to the angle range and the angle number, that is, the plane wave angle value corresponding to the transmission angle number of 5 is [-10°, -5°, 0°, 5°, 10°]. The transmitting end generates 5 echo signal data according to the 5 plane wave transmission angles, and the 5 echo signal data are compounded to generate a frame of plane wave echo data. Similarly, if the preset angle number becomes 6, the 6 generated echo data are compounded to generate another frame of plane wave echo data, and the transmission angle number is changed until the Nth frame of plane wave echo data is generated.

[0029] Step 102, generating a pre-stored association relationship according to the multiple sets of plane wave echo data;

[0030] The blood flow model is used to simulate human blood vessels. Under the intervention of ultrasound contrast agent microbubbles, the microbubble contrast agent is injected into the tube. Therefore, when any frame of plane wave echo data is received, the contrast-to-noise ratio (CNR) of the echo data can be obtained by calculating the ratio of the microbubble data inside the tube to the noise data outside the tube. Specifically, two regional signals with the same area size and the same depth are selected according to the received plane wave echo data. The two regional signals represent the microbubble data inside the tube and the noise data outside the tube, respectively. Figure 2 As shown, the contrast-to-noise ratio is obtained by calculating the ratio of the microbubble data inside the tube to the noise data outside the tube. The contrast-to-noise ratio can be calculated using formula (1).

[0031]

[0032] IN represents the microbubble area inside the tube, and OUT represents the area outside the tube.

[0033] In addition, the size of the contrast-to-noise ratio will be affected by multiple factors such as the depth of the selected area IN and area OUT, the blood flow velocity in the microbubble, and the number of plane wave emission angles. Therefore, assuming that the range of emission angles is fixed, at different depths, different blood flow velocities, and different numbers of plane wave angles, the calculated contrast-to-noise ratio (CNR) values ​​are also different, such as Figure 3a In addition, the size of the contrast-to-noise ratio is also affected by the angle range of the plane wave emission. When the angle range of the plane wave emission is not fixed, the contrast-to-noise ratio obtained even at the same number of angles is different, such as Figure 3b As shown, the calculation method of the contrast-to-noise ratio is the same and will not be described in detail here.

[0034] After all the contrast-to-noise ratio (CNR) values ​​are calculated, the number of plane wave angles required to reach the maximum CNR value for each blood flow velocity at each depth is determined by comparing all the CNR values. For example, at a depth of x and a flow velocity of y, the contrast-to-noise ratio (CNR) values ​​of z angles are calculated, and these z contrast-to-noise ratio (CNR) data are expressed in the form of a curve, as shown in the figure below: Figure 4 As shown in the figure, when the number of plane wave transmission angles is small, as the number of angles increases, the contrast-to-noise ratio (CNR) increases slowly. At this time, the effect of decorrelation of angle signals is not obvious. As the number of angles gradually increases, the signal attenuation caused by decorrelation of angle signals becomes more and more obvious, until it is greater than the improvement of the contrast-to-noise ratio (CNR) by the increase in angles. Therefore, as the number of angles increases, the contrast-to-noise ratio (CNR) shows a trend of first increasing and then decreasing. Specifically, as Figure 4 As shown in the figure, the angle number A corresponding to the maximum contrast-to-noise ratio (CNR) is the optimal number of plane wave angles at depth x and flow velocity y. This situation is for scenes with flow velocity. If the flow velocity is 0, the size of the contrast-to-noise ratio will increase monotonically with the increase of the angle number.

[0035] Therefore, the number of angles corresponding to the maximum value of the contrast-to-noise ratio (CNR) is taken as the optimal number of plane wave emission angles. For some extreme values ​​that do not have inflection points, such as when the velocity is very small or very large, the number of angles corresponding to the maximum value of the contrast-to-noise ratio (CNR) can still be selected as the optimal number of plane wave emission angles. After counting and calculating all contrast-to-noise ratio (CNR) data, we determine the optimal number of plane wave emission angles for each blood flow velocity to achieve the highest contrast-to-noise ratio at each scanning depth, forming a pre-stored association relationship to facilitate subsequent indexing operations.

[0036] Step 103, obtaining echo data of the blood vessel scanning section, and calculating the maximum blood flow velocity and the average blood flow velocity;

[0037] A plane wave is emitted to the blood vessel according to a preset number of angles to obtain reflected blood flow echo data, and the blood flow echo data is processed to obtain the blood flow velocity at each sampling point in the echo data. Specifically, the plane wave deflection angle is adjusted in sequence according to the preset angle, and the echo data at each deflection angle is obtained, beam synthesis is performed on the echo data, and the I / Q data at two adjacent deflection angles is calculated using the Doppler frequency shift method, and the blood flow velocity at each sampling point in the echo data is obtained based on the I / Q data. Alternatively, two adjacent plane waves are emitted according to a preset number of angles, and two frames of echo data are respectively composited to generate two frames of echo data, and the I / Q data of the two frames of echo data are calculated using the Doppler frequency shift method to obtain the blood flow velocity at each sampling point in the echo data.

[0038] According to the blood flow velocity of each sampling point in the echo data, its maximum blood flow velocity is determined. However, in order to eliminate the velocity interference caused by intense movements such as breathing, so that the maximum blood flow velocity we obtain is not caused by external influences, we can preset a cumulative probability, such as 0.95, and calculate its cumulative probability distribution according to different blood flow velocities in the echo data, and obtain the maximum blood flow velocity corresponding to the cumulative probability that is the same as the preset probability, such as Figure 5 As shown, assuming that m is the preset probability, the corresponding blood flow velocity n is the maximum blood flow velocity, denoted as S cdf If we calculate that the cumulative probability corresponding to different blood flow velocities is not exactly the same as the preset probability, the blood flow velocity corresponding to the probability closest to the preset probability is taken as the maximum blood flow velocity. For example, the blood flow velocity corresponding to the cumulative probability of 0.947 is 10 mm / s, and the velocity value corresponding to 0.951 is 12 mm / s, so the maximum blood flow velocity is 12 mm / s.

[0039] However, considering that only a small part of some areas to be scanned are high-velocity blood vessels, and most of the rest are solid or low-velocity blood flow. In order to ensure the signal strength of high-speed blood flow, reducing the plane wave transmission angle will lead to a decrease in the contrast-to-noise ratio (CNR) of most of the remaining solid or low-velocity blood flow. In order to calculate the maximum blood flow velocity in this case, we can calculate the average blood flow velocity based on the blood flow velocity of each sampling point in the echo data. The transmission angle corresponding to the average blood flow velocity can ensure the contrast-to-noise ratio (CNR) of solid or low-velocity blood flow.

[0040] Step 104, determining the optimal number of plane wave emission angles according to the average blood flow velocity and the maximum blood flow velocity;

[0041] Step 105, transmitting the plane wave at the optimal number of plane wave transmission angles, and compounding the reflected echo data to generate an image;

[0042] According to the maximum blood flow velocity S cdf and mean blood flow velocity S pdf , if the maximum blood flow velocity S cdf and mean blood flow velocity S pdf If the difference is less than the preset threshold, the maximum blood flow velocity S cdf As a blood flow velocity for calculating scanning angiography imaging, a pre-stored association relationship is indexed to obtain an optimal number of plane wave emission angles, a plane wave is emitted at the optimal number of emission angles, and the reflected echo data is compounded to generate an image.

[0043] If a completely matching blood flow velocity is not found when indexing the pre-stored association relationship, the number of angles corresponding to the blood flow velocity closest to the velocity can be found as the optimal number of plane wave emission angles.

[0044] If the maximum blood flow velocity S cdf and mean blood flow velocity S pdf If the difference between the two is greater than or equal to the preset threshold, the average blood flow velocity S pdf As a blood flow velocity for scanning angiography imaging, a pre-stored association relationship is indexed to obtain the optimal number M of plane wave emission angles.

[0045] like Figure 6 As shown, the plane wave is emitted with the optimal plane wave emission angle number M, and the M reflected echo data are compounded to generate a first frame of image. The corresponding optimal plane wave emission angle number N is obtained with the maximum blood flow velocity, where M is greater than or equal to N, and the middle symmetrical N echo data are selected from the M reflected echo data for compounding to generate a second frame of image. The first frame of image and the second frame of image are compounded to generate an image. Before generating the image, the composite data needs to be subjected to envelope calculation and logarithmic compression processing.

[0046] Specifically, for example, the number of optimal plane wave emission angles M is 7, the number of optimal plane wave emission angles N corresponding to the maximum blood flow velocity is 3, and the preset angle range is [-15°, 15°], then the angle values ​​corresponding to the M number of angles are [-15°, -10°, -5°, 0°, 5°, 10°, 15°], and the echo data generated by transmitting these 7 angles are compounded to generate the first frame of image, and the number of angles N is 3, then the echo data of the 3 angle values ​​symmetrical among the 7 angle values, that is, the echo data corresponding to [-5°, 0°, 5°] are compounded to generate the second frame of image.

[0047] An embodiment of the present invention provides a contrast imaging system based on adjusting the number of plane wave emission angles, the system comprising: a pre-stored association relationship module, used to determine the optimal number of plane wave emission angles for achieving the highest contrast-to-noise ratio (CNR) for each blood flow velocity at each scanning depth under a simulated environment; a blood flow velocity processing module, used to process the blood flow echo data to obtain the blood flow velocity of each sampling point in the echo data, and determine its maximum blood flow velocity and average blood flow velocity; an image processing module, used to determine the corresponding optimal number of plane wave emission angles according to the maximum blood flow velocity and the average blood flow velocity, and generate an image. An image output module, used to output the final image, the system is used to execute any of the above contrast imaging methods based on adjusting the number of plane wave emission angles.

[0048] An embodiment of the present invention further provides a storage medium storing a computer program, wherein the computer program, when executed by a processor, implements the angiography imaging method for adjusting the plane wave emission angle as described in any one of the above items.

[0049] In summary, the present invention provides a method, system and storage medium for adjusting the number of plane wave emission angles for angiography. In a simulated environment, a pre-stored association relationship is generated; the blood flow velocity of the angiography is calculated based on the echo data in the blood vessel scanning section, and the optimal number of plane wave emission angles corresponding to the scanning depth and blood flow velocity information of the scanning section is obtained based on the pre-stored association relationship. The number of angles for transmitting plane waves is dynamically adjusted to improve the flexibility of parameter adjustment. The plane wave is emitted with the optimal number of plane wave emission angles, and the reflected echo data is compounded, and the envelope is calculated, logarithmic compression is performed on it, and an image is generated, thereby improving the image quality of plane wave angiography.

[0050] It should be understood that although this specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each implementation mode may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

[0051] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent implementation methods or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A contrast imaging method based on adjusting the plane wave emission angle, characterized in that: The method comprises: Receiving echo data in the scanning section, calculating the blood flow velocity of the contrast imaging according to the echo data, and indexing the pre-stored association relationship to obtain the optimal number of plane wave emission angles corresponding to the scanning depth and blood flow velocity information of the scanning section; The plane wave is emitted at the optimal number of plane wave emission angles, and the reflected echo data is compounded to generate an image; wherein the pre-stored association relationship is: Under a simulated environment, determining the optimal number of plane wave emission angles for achieving the highest contrast-to-noise ratio for each blood flow velocity at each scanning depth; the contrast-to-noise ratio is obtained by calculating the ratio of intravascular microbubble data to extravascular noise data; The plane wave is emitted at the optimal plane wave emission angle number M corresponding to the average blood flow velocity, and the M reflected echo data are compounded to generate a first frame of image; The number N of optimal plane wave emission angles corresponding to the maximum blood flow velocity is obtained; Selecting N symmetrical echo data in the middle from the M reflected echo data for compounding to generate a second frame of image; The first frame image and the second frame image are composited to generate an image.

2. The method according to claim 1, characterized in that The method comprises: obtaining a maximum blood flow velocity and an average blood flow velocity of the echo data; If the difference between the maximum blood flow velocity and the average blood flow velocity is less than a preset threshold, the maximum blood flow velocity is used as the blood flow velocity for calculating contrast imaging to obtain the optimal number of plane wave emission angles.

3. The method according to claim 1, characterized in that The method comprises: If the difference between the maximum blood flow velocity and the average blood flow velocity is greater than or equal to a preset threshold, the average blood flow velocity is used as the blood flow velocity for calculating the contrast imaging to obtain the optimal number of plane wave emission angles.

4. The method according to claim 1, characterized in that The method comprises: In the simulation environment, the echo data of the transmitted plane wave includes noise data outside the tube and microbubble data inside the tube.

5. The method according to claim 4, characterized in that The method further comprises: arbitrarily selecting the in-tube microbubble data and the out-tube noise data having the same area and scanning depth from the echo data of the emitted plane wave; The ratio of the microbubble data inside the tube to the noise data outside the tube is calculated to obtain the contrast-to-noise ratio of the echo data.

6. The method according to claim 1, characterized in that The method further comprises: Each scanning depth, each blood flow velocity, and each plane wave emission angle number for calculating the contrast-to-noise ratio are all within a preset range.

7. The method according to claim 1, characterized in that The “calculating the blood flow velocity of the contrast imaging according to the echo data” specifically includes: Adjust the plane wave deflection angle in sequence according to the preset angles, and obtain echo data at each deflection angle; Performing beam synthesis on the echo data, and calculating I / Q data at two adjacent deflection angles using a Doppler frequency shift method; The blood flow velocity at each sampling point in the echo data is acquired according to the I / Q data.

8. A radiographic imaging system based on adjusting the plane wave emission angle, characterized in that: The system comprises: a pre-stored association relationship module, a plane wave echo receiving module, a blood flow velocity processing module, an image processing module, and an image output module. The system is used to execute the method according to any one of claims 1 to 7.

9. A storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

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