Ultrasonic blood flow imaging method and ultrasonic imaging device

Abstract

An ultrasonic blood flow imaging method and an ultrasonic imaging device, the method comprising: emitting first to third ultrasonic waves at a first emission angle to a blood flow position to be measured of a target object to obtain a first projection component of a blood flow velocity vector of the blood flow position to be measured at the first emission angle, wherein there is a first pulse repetition frequency between the first ultrasonic wave and the second ultrasonic wave, and there is a second pulse repetition frequency between the second ultrasonic wave and the third ultrasonic wave, and the first pulse repetition frequency and the second pulse repetition frequency are not in an integer multiple relationship; emitting fourth to sixth ultrasonic waves at a second emission angle to the blood flow position to be measured to obtain a second projection component of the blood flow velocity vector of the blood flow position to be measured at the second emission angle, wherein there is a third pulse repetition frequency between the fourth ultrasonic wave and the fifth ultrasonic wave, and there is a fourth pulse repetition frequency between the fifth ultrasonic wave and the sixth ultrasonic wave, and the third pulse repetition frequency and the fourth pulse repetition frequency are not in an integer multiple relationship.

Description

Technical Field

[0001] The present application relates to the field of ultrasonic imaging technology, and more particularly to an ultrasonic blood flow imaging method and an ultrasonic imaging device. Background Art

[0002] For ultrasonic blood flow imaging based on the Doppler principle, if the actual blood flow velocity exceeds the maximum measurable velocity of the imaging system, aliasing will occur in the measurement result, making the obtained measured value incorrect. Increasing the Pulse Repetition Frequency (PRF for short) and decreasing the center frequency of the transmitted waveform can increase the maximum measurable velocity. However, the PRF is limited by the sound velocity and imaging depth and cannot be increased indefinitely. In ultrasonic vector blood flow imaging, when multiple transmission angles are used, due to the limitation of imaging depth, the PRF for calculating velocity between the same angles is even lower, and aliasing is more likely to occur, resulting in incorrect measured values. Vector blood flow imaging focuses more on the accuracy of quantitative measurement, so the occurrence of aliasing should be avoided more. Summary of the Invention

[0003] The present application is proposed to solve the above problems. According to one aspect of the present application, there is provided an ultrasonic blood flow imaging method, the method comprising: transmitting a first ultrasonic wave, a second ultrasonic wave, and a third ultrasonic wave to a blood flow position to be measured of a target object at a first transmission angle, and receiving the echoes of the ultrasonic waves to obtain a first echo signal, a second echo signal, and a third echo signal; wherein, there is a first pulse repetition frequency between the first ultrasonic wave and the second ultrasonic wave, and there is a second pulse repetition frequency between the second ultrasonic wave and the third ultrasonic wave, and the first pulse repetition frequency and the second pulse repetition frequency are not in an integer multiple relationship; transmitting a fourth ultrasonic wave, a fifth ultrasonic wave, and a sixth ultrasonic wave to the blood flow position to be measured at a second transmission angle different from the first transmission angle, and receiving the echoes of the ultrasonic waves to obtain a fourth echo signal, a fifth echo signal, and a sixth echo signal; wherein, there is a third pulse repetition frequency between the fourth ultrasonic wave and the fifth ultrasonic wave, and there is a fourth pulse repetition frequency between the fifth ultrasonic wave and the sixth ultrasonic wave, and the third pulse repetition frequency and the fourth pulse repetition frequency are not in an integer multiple relationship; obtaining a first projection component of the blood flow velocity vector at the blood flow position to be measured on the first transmission angle according to the first echo signal, the second echo signal, the third echo signal, the first pulse repetition frequency, and the second pulse repetition frequency; obtaining a second projection component of the blood flow velocity vector at the blood flow position to be measured on the second transmission angle according to the fourth echo signal, the fifth echo signal, the sixth echo signal, the third pulse repetition frequency, and the fourth pulse repetition frequency; and synthesizing the first projection component and the second projection component to obtain the blood flow velocity vector at the blood flow position to be measured.

[0004] According to another aspect of the present application, an ultrasonic blood flow imaging method is provided. The method includes: emitting a first ultrasonic wave, a second ultrasonic wave, a third ultrasonic wave, and a fourth ultrasonic wave at a first emission angle to a blood flow position to be measured of a target object, and receiving the echoes of the ultrasonic waves to obtain a first echo signal, a second echo signal, a third echo signal, and a fourth echo signal; wherein, a first pulse repetition frequency exists between the first ultrasonic wave and the second ultrasonic wave, a second pulse repetition frequency exists between the third ultrasonic wave and the fourth ultrasonic wave, and the first pulse repetition frequency and the second pulse repetition frequency are non-integer multiple relationships; emitting a fifth ultrasonic wave, a sixth ultrasonic wave, a seventh ultrasonic wave, and an eighth ultrasonic wave at a second emission angle different from the first emission angle to the blood flow position to be measured, and receiving the echoes of the ultrasonic waves to obtain a fifth echo signal, a sixth echo signal, a seventh echo signal, and an eighth echo signal; wherein, a third pulse repetition frequency exists between the fifth ultrasonic wave and the sixth ultrasonic wave, a fourth pulse repetition frequency exists between the seventh ultrasonic wave and the eighth ultrasonic wave, and the third pulse repetition frequency and the fourth pulse repetition frequency are non-integer multiple relationships; obtaining a first projection component of the blood flow velocity vector at the blood flow position to be measured on the first emission angle according to the first echo signal, the second echo signal, the third echo signal, the fourth echo signal, the first pulse repetition frequency, and the second pulse repetition frequency; obtaining a second projection component of the blood flow velocity vector at the blood flow position to be measured on the second emission angle according to the fifth echo signal, the sixth echo signal, the seventh echo signal, the eighth echo signal, the third pulse repetition frequency, and the fourth pulse repetition frequency; and synthesizing the first projection component and the second projection component to obtain the blood flow velocity vector at the blood flow position to be measured.

[0005] According to another aspect of the present application, there is provided an ultrasonic blood flow imaging method, the method comprising: transmitting a first ultrasonic wave, a second ultrasonic wave, and a third ultrasonic wave at a first emission angle to a blood flow position to be measured of a target object, and receiving echoes of the ultrasonic waves to obtain a first echo signal, a second echo signal, and a third echo signal; wherein, there is a first pulse repetition frequency between the first ultrasonic wave and the second ultrasonic wave, there is a second pulse repetition frequency between the second ultrasonic wave and the third ultrasonic wave, and the first pulse repetition frequency and the second pulse repetition frequency are not in an integer multiple relationship; transmitting a fourth ultrasonic wave, a fifth ultrasonic wave, a sixth ultrasonic wave, and a seventh ultrasonic wave at a second emission angle different from the first emission angle to the blood flow position to be measured, and receiving echoes of the ultrasonic waves to obtain a fourth echo signal, a fifth echo signal, a sixth echo signal, and a seventh echo signal; wherein, there is a third pulse repetition frequency between the fourth ultrasonic wave and the fifth ultrasonic wave, there is a fourth pulse repetition frequency between the sixth ultrasonic wave and the seventh ultrasonic wave, and the third pulse repetition frequency and the fourth pulse repetition frequency are not in an integer multiple relationship; obtaining a first projection component of the blood flow velocity vector at the blood flow position to be measured on the first emission angle according to the first echo signal, the second echo signal, the third echo signal, the first pulse repetition frequency, and the second pulse repetition frequency; obtaining a second projection component of the blood flow velocity vector at the blood flow position to be measured on the second emission angle according to the fourth echo signal, the fifth echo signal, the sixth echo signal, the seventh echo signal, the third pulse repetition frequency, and the fourth pulse repetition frequency; and synthesizing the first projection component and the second projection component to obtain the blood flow velocity vector at the blood flow position to be measured.

[0006] According to still another aspect of the present application, there is provided an ultrasonic imaging device, the device comprising a transmitting circuit, a receiving circuit, an ultrasonic probe, and a processor, wherein: the transmitting circuit is configured to control the ultrasonic probe to transmit ultrasonic waves to a blood flow position to be measured of a target object; the receiving circuit is configured to control the ultrasonic probe to receive echoes of the ultrasonic waves and obtain echo signals from the echoes of the ultrasonic waves; the processor is configured to perform ultrasonic blood flow imaging based on the echo signals; and the processor is further configured to execute the above ultrasonic blood flow imaging method.

[0007] The ultrasonic blood flow imaging method and the ultrasonic imaging device according to the embodiments of the present application transmit ultrasonic waves to the blood flow position to be measured of a target object at at least two emission angles, and each emission angle uses a non-uniform PRF to transmit ultrasonic waves, which can achieve a larger actual PRF, thereby increasing the maximum measurable speed, and further improving the measurement accuracy of the blood flow velocity vector at the blood flow position to be measured. Description of the Drawings

[0008] The above and other objects, features, and advantages of the present application will become more apparent by describing the embodiments of the present application in more detail with reference to the accompanying drawings. The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation to the present application. In the drawings, the same reference numerals generally represent the same components or steps.

[0009] Figure 1 A schematic flowchart showing an ultrasonic blood flow imaging method according to an embodiment of the present application.

[0010] Figure 2 An exemplary schematic diagram showing the transmission of ultrasonic waves in the ultrasonic blood flow imaging method according to an embodiment of the present application.

[0011] Figure 3 An exemplary schematic diagram showing the transmission of focused ultrasonic waves between non-focused ultrasonic waves in the ultrasonic blood flow imaging method according to an embodiment of the present application.

[0012] Figure 4 An example diagram showing the grouping of the transmitted ultrasonic waves in the ultrasonic blood flow imaging method according to an embodiment of the present application to perform wall filtering on their respective echo signals.

[0013] Figure 5 Another example diagram showing the grouping of the transmitted ultrasonic waves in the ultrasonic blood flow imaging method according to an embodiment of the present application to perform wall filtering on their respective echo signals.

[0014] Figure 6 An exemplary schematic diagram showing the continuous transmission of multiple times at the same angle and the same PRF in the ultrasonic blood flow imaging method according to an embodiment of the present application.

[0015] Figure 7 A schematic flowchart showing an ultrasonic blood flow imaging method according to another embodiment of the present application.

[0016] Figure 8 A schematic structural block diagram showing an ultrasonic imaging device according to an embodiment of the present application. Detailed implementation manners

[0017] In order to make the objectives, technical solutions, and advantages of the present application more apparent, the exemplary embodiments according to the present application will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. It should be understood that the present application is not limited by the exemplary embodiments described herein. Based on the embodiments of the present application described in the present application, all other embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present application.

[0018] Figure 1 FIG. 1 shows a schematic flowchart of an ultrasonic blood flow imaging method 100 according to an embodiment of the present application. As Figure 1 shown, the ultrasonic blood flow imaging method 100 may include the following steps:

[0019] In step S110, first, second, and third ultrasonic waves are transmitted toward the blood flow position to be measured of the target object at a first transmission angle, and the echoes of the ultrasonic waves are received to obtain a first echo signal, a second echo signal, and a third echo signal; wherein, a first pulse repetition frequency exists between the first ultrasonic wave and the second ultrasonic wave, a second pulse repetition frequency exists between the second ultrasonic wave and the third ultrasonic wave, and the first pulse repetition frequency and the second pulse repetition frequency are not in an integer multiple relationship.

[0020] In step S120, fourth, fifth, and sixth ultrasonic waves are transmitted toward the blood flow position to be measured at a second transmission angle different from the first transmission angle, and the echoes of the ultrasonic waves are received to obtain a fourth echo signal, a fifth echo signal, and a sixth echo signal; wherein, a third pulse repetition frequency exists between the fourth ultrasonic wave and the fifth ultrasonic wave, a fourth pulse repetition frequency exists between the fifth ultrasonic wave and the sixth ultrasonic wave, and the third pulse repetition frequency and the fourth pulse repetition frequency are not in an integer multiple relationship;

[0021] In step S130, according to the first echo signal, the second echo signal, the third echo signal, the first pulse repetition frequency, and the second pulse repetition frequency, a first projection component of the blood flow velocity vector at the blood flow position to be measured on the first transmission angle is obtained;

[0022] In step S140, according to the fourth echo signal, the fifth echo signal, the sixth echo signal, the third pulse repetition frequency, and the fourth pulse repetition frequency, a second projection component of the blood flow velocity vector at the blood flow position to be measured on the second transmission angle is obtained;

[0023] In step S150, the first projection component and the second projection component are synthesized to obtain the blood flow velocity vector at the blood flow position to be measured.

[0024] In the embodiment of the present application, ultrasonic waves are transmitted toward the blood flow position to be measured of the target object at at least two transmission angles, at least two pulse repetition frequencies (i.e., PRFs) exist between the ultrasonic waves transmitted at each transmission angle, and these at least two PRFs are not in an integer multiple relationship, which means that non-uniform PRFs are used to transmit ultrasonic waves at each transmission angle. This can achieve a larger actual PRF, thereby increasing the maximum measurable speed, and further improving the measurement accuracy of the blood flow velocity vector at the blood flow position to be measured. The reasons why the ultrasonic blood flow imaging method 100 can increase the maximum measurable speed will be described in detail below.

[0025] First, the blood flow velocity calculation formula based on the Doppler principle is as follows:

[0026]

[0027] Where:

[0028]

[0029] In the above formula (1), v z is the blood flow velocity component measured along the ultrasonic propagation direction, f0 is the center frequency of the probe transmitted signal, f PRF is the pulse repetition frequency PRF (i.e., the reciprocal of the time interval between two adjacent transmissions); N in the R(1) expression is the number of transmissions at the same position, x(i) represents the real part of the signal after the i-th transmission and reception processing, and y(i) represents the imaginary part of the signal after the i-th transmission and reception processing; is the imaginary part operator, is the real part operator, and j is the imaginary unit.

[0030] For the sake of convenient expression, let The variation range of arctan(A) is (-π, π], then the maximum measurable velocity (taking the absolute value) of formula (1) can be expressed as:

[0031]

[0032] The velocity measurement range of formula (1) can be expressed as [-v max v max ). When the actual velocity is greater than v max or less than -v max , the measurement result will be aliased (Note: The actual velocity here refers to the actual value of the velocity component along the ultrasonic emission direction, and this value is also measured). The correct measured value of the velocity component should be:

[0033]

[0034] When there is no aliasing, M = 0, and formula (2) is equivalent to formula (1). When aliasing occurs, M is a non-zero integer, including positive integers and negative integers. For example, -3, -2, -1, 1, 2, 3, etc. Since M is unknown, more information is needed to obtain v z-corr .

[0035] Based on this, in the embodiment of the present application, the ultrasonic blood flow imaging method 100 emits ultrasonic waves to the blood flow position to be measured of the target object at two emission angles, and there are two different PRFs between the ultrasonic waves emitted at each emission angle. We take the two PRFs at the first emission angle as an example to describe, and represent the first pulse repetition frequency as f PRF1, represent the second pulse repetition frequency as f PRF2 . Based on this, Equation (2) can be extended to a system of equations containing two PRFs:

[0036]

[0037]

[0038] Although the two equations of Equation (3) and Equation (4) have three unknowns (i.e., v z-corr , M, and N), since M and N are integers, this system of equations is solvable in some cases.

[0039] First, aliasing will occur first for the smaller PRF. Therefore, when f PRF1 > f PRF2 , then |M| ≤ |N|; conversely, when f PRF1 < f PRF2 , then |M| ≥ |N|.

[0040] To further simplify, let:

[0041]

[0042] Then Equation (3) and (4) can be further expressed as:

[0043] v z-corr = B1 + 2Mv max1 (5)

[0044] v z-corr = B2 + 2Nv max2 (6)

[0045] where, |B1| ≤ v max1 , |B2| ≤ v max2 . Combining (5) and (6), we get:

[0046] B1 - B2 = 2(Nv max2 - Mv max1 ) (7)

[0047] In Equation (7), B1, B2, v max1 , v max2 are known. Different M and N can be tried to make Equation (7) hold as much as possible. This operation can be further formulated as:

[0048]

[0049] In Equation (8), It represents the set of integers. Multiple sets of solutions for M and N can be found by the exhaustive method, and then the M or N with the smallest absolute value is substituted into formula (3) or (4) to calculate the actual velocity after anti-aliasing.

[0050] Since there are two unknowns, M and N, in formula (7), there are infinitely many sets of solutions to make this equation hold. Therefore, each set of M and N corresponds to a measurement result during calculation, so there are infinitely many measured values, that is to say, these measured values may all be the actual blood flow velocities. Considering that the blood flow velocity cannot be infinitely large, it is generally considered that the velocity measurement value corresponding to the M or N with the smallest absolute value is the actual velocity measurement value. Of course, this belongs to an assumption. When the actual measurement value is greater than the velocity measurement value corresponding to the M or N with the smallest absolute value, it is also equivalent to aliasing occurring. However, the maximum measurable velocity of this method is much higher than the traditional method.

[0051] Therefore, the ultrasonic blood flow imaging method 100 according to the embodiment of the present application emits ultrasonic waves to the blood flow position to be measured of the target object at at least two emission angles, and each emission angle emits ultrasonic waves with a non-uniform PRF, which can achieve a larger actual PRF, thereby increasing the maximum measurable velocity, and further improving the measurement accuracy of the blood flow velocity vector at the blood flow position to be measured.

[0052] Here, it should be noted that the order of steps S110 to S150 of the ultrasonic blood flow imaging method 100 according to the embodiment of the present application is not necessarily limited by their serial numbers. For example, step S120 can also be after step S130.

[0053] In the embodiment of the present application, step S130 obtaining the first projection component of the blood flow velocity vector at the blood flow position to be measured at the first emission angle according to the first echo signal, the second echo signal, the third echo signal, the first pulse repetition frequency, and the second pulse repetition frequency may include: obtaining the first blood flow velocity according to the first echo signal and the second echo signal, and obtaining the second blood flow velocity according to the second echo signal and the third echo signal; obtaining the first maximum measurable velocity corresponding to the first pulse repetition frequency and the second maximum measurable velocity corresponding to the second pulse repetition frequency; determining a first anti-aliasing coefficient that satisfies a first preset condition according to the first blood flow velocity, the second blood flow velocity, the first maximum measurable velocity, and the second maximum measurable velocity; and performing anti-aliasing processing on the first blood flow velocity and / or the second blood flow velocity based on the first anti-aliasing coefficient to obtain the first projection component of the blood flow velocity vector at the blood flow position to be measured at the first emission angle.

[0054] The process of calculating the first projection component of the blood flow velocity vector at the position of the blood flow to be measured in this embodiment can be understood in combination with the formula in the previous text. Among them, the first blood flow velocity can be understood as B1 in the previous formula (8), and the second blood flow velocity can be understood as B2 in the previous formula (8); the first maximum measurable velocity can be understood as v in the previous formula (8). max1 , and the second maximum measurable velocity can be understood as v in the previous formula (8). max2 ; the first aliasing removal coefficient can be understood as M and / or N in the previous formula (8); the first preset condition can be understood as making the formula (8) hold.

[0055] Based on this, determining the first aliasing removal coefficient that satisfies the first preset condition according to the first blood flow velocity, the second blood flow velocity, the first maximum measurable velocity, and the second maximum measurable velocity may include: taking the difference between the first blood flow velocity and the second blood flow velocity as the first difference (i.e., B1 - B2); taking twice the difference between N times the second maximum measurable velocity and M times the first maximum measurable velocity as the second difference (i.e., 2(Mv max2 - Mv max1 ), where both N and M are integers; taking the difference between the first difference and the second difference as the third difference (i.e., (B1 - B2) - 2(Nv max2 - Mv max1 )); calculating the value results of M and N that make the absolute value of the third difference reach the minimum (i.e., formula (8)), and taking M and / or N in the value results as the first aliasing removal coefficient.

[0056] Since the value result of M corresponds to the first blood flow velocity B1, therefore, when the value result of M is used as the first aliasing removal coefficient, the first blood flow velocity is de - aliased based on the first aliasing removal coefficient to obtain the first projection component of the blood flow velocity vector at the position of the blood flow to be measured at the first emission angle, that is, the first projection component of the blood flow velocity vector at the position of the blood flow to be measured at the first emission angle is calculated through the previous formula (5). Since the value result of N corresponds to the first blood flow velocity B2, therefore, when the value result of N is used as the first aliasing removal coefficient, the second blood flow velocity is de - aliased based on the first aliasing removal coefficient to obtain the first projection component of the blood flow velocity vector at the position of the blood flow to be measured at the first emission angle, that is, the first projection component of the blood flow velocity vector at the position of the blood flow to be measured at the first emission angle is calculated through the previous formula (6). It is also possible to average the projection component obtained by de - aliasing the first blood flow velocity with M as the first aliasing removal coefficient and the projection component obtained by de - aliasing the first blood flow velocity with N as the first aliasing removal coefficient, and take the averaged result as the final first projection component of the blood flow velocity vector at the position of the blood flow to be measured at the first emission angle.

[0057] In an embodiment of the present application, when there are at least two sets of value results of M and N such that the absolute value of the aforementioned third difference reaches the minimum value, the M and / or N with the smallest absolute value in the value results can be used as the first anti-aliasing coefficient, which will be described in combination with examples later in the text.

[0058] In an embodiment of the present application, obtaining the second projection component of the blood flow velocity vector at the position of the blood flow to be measured on the second emission angle according to the fourth echo signal, the fifth echo signal, the sixth echo signal, the third pulse repetition frequency, and the fourth pulse repetition frequency in step S140 may include: obtaining the third blood flow velocity according to the fourth echo signal and the fifth echo signal, and obtaining the fourth blood flow velocity according to the fifth echo signal and the sixth echo signal; obtaining the third maximum measurable velocity corresponding to the third pulse repetition frequency and the fourth maximum measurable velocity corresponding to the fourth pulse repetition frequency; determining a second anti-aliasing coefficient that satisfies a second preset condition according to the third blood flow velocity, the fourth blood flow velocity, the third maximum measurable velocity, and the fourth maximum measurable velocity; and performing anti-aliasing processing on the third blood flow velocity and / or the fourth blood flow velocity based on the second anti-aliasing coefficient to obtain the second projection component of the blood flow velocity vector at the position of the blood flow to be measured on the second emission angle.

[0059] Here, the method for calculating the second projection component of the blood flow velocity vector at the position of the blood flow to be measured is similar to the method for calculating the first projection component described above, except that different data are used in the calculation. For the sake of understanding, let the third pulse repetition frequency be f PRF3 , and the fourth pulse repetition frequency be f PRF4 , then the previous formulas (5) to (8) can be transformed as follows respectively:

[0060] v z-corr = B3 + 2Mv max3 (9)

[0061] v z-corr = B4 + 2Nv max4 (10)

[0062] B3 - B4 = 2(Nv max4 - Mv max3 ) (11)

[0063] argmin M,N |(B3 - B4) - 2(Nv max4 - Mv max3 )| (12)

[0064] Therefore, the third blood flow velocity can be understood as B3 in the previous formula (12), and the fourth blood flow velocity can be understood as B4 in the previous formula (12); the third maximum measurable velocity can be understood as v max3The fourth maximum measurable speed can be understood as v in the previous formula (12) max4 ; The second anti-aliasing coefficient can be understood as M and / or N in the previous formula (12); The second preset condition can be understood as making formula (12) valid. Wherein M and N in formula (5) to formula (8) have the same meaning as M and N in formula (9) to formula (12), but there will be different value results based on different data sources. The same letter representation here is only for exemplary explanation, and does not mean that the two are necessarily the same.

[0065] Based on this, determining the second anti-aliasing coefficient that meets the second preset condition according to the third blood flow velocity, the fourth blood flow velocity, the third maximum measurable velocity, and the fourth maximum measurable velocity may include: taking the difference between the third blood flow velocity and the fourth blood flow velocity as the fourth difference (i.e., B3-B4); taking twice the difference between N times the fourth maximum measurable velocity and M times the third maximum measurable velocity as the fifth difference (i.e., 2(Nv max4 -Mv max3 )), where N and M are both integers; the difference between the fourth difference and the fifth difference is taken as the sixth difference (ie (B3-B4)-2(Nv max4 -Mv max3 )); calculate the value results of M and N that make the absolute value of the sixth difference reach the minimum value (ie, formula (12)), and use M and / or N in the value results as the second anti-aliasing coefficient.

[0066] Since the value of M corresponds to the third blood flow velocity B3, when the value of M is used as the second anti-aliasing coefficient, the third blood flow velocity is subjected to anti-aliasing processing based on the second anti-aliasing coefficient to obtain the second projection component of the blood flow velocity vector at the blood flow position to be measured at the second emission angle, that is, the second projection component of the blood flow velocity vector at the blood flow position to be measured at the second emission angle is calculated by the above formula (9). Since the value of N corresponds to the fourth blood flow velocity B4, when the value of N is used as the second anti-aliasing coefficient, the fourth blood flow velocity is subjected to anti-aliasing processing based on the second anti-aliasing coefficient to obtain the second projection component of the blood flow velocity vector at the blood flow position to be measured at the second emission angle, that is, the second projection component of the blood flow velocity vector at the blood flow position to be measured at the second emission angle is calculated by the above formula (10). The projection component obtained by anti-aliasing the third blood flow velocity using the above M as the second anti-aliasing coefficient and the projection component obtained by anti-aliasing the fourth blood flow velocity using the above N as the second anti-aliasing coefficient are averaged, and the averaged result is used as the second projection component of the blood flow velocity vector at the final blood flow position to be measured at the first emission angle.

[0067] In an embodiment of the present application, when there are at least two sets of value-taking results of M and N such that the absolute value of the sixth difference reaches the minimum value, the M and / or N with the smallest absolute value in the value-taking results is used as the second anti-aliasing coefficient.

[0068] Now, some examples of the method 100 according to the embodiment of the present application will be described by taking the first emission angle as an example. It should be understood that the situation is similar for the second emission angle.

[0069] In one example, assuming that the first pulse repetition frequency is 3k (i.e., 3000 Hz), the second pulse repetition frequency is 4k (i.e., 4000 Hz), when the sound speed c is 1540 m / s and the center frequency of the probe transmitting signal is 5 MHz, the maximum measurable speeds (taking the absolute value) corresponding to the first pulse repetition frequency and the second pulse repetition frequency are respectively:

[0070]

[0071]

[0072] The following describes how to obtain the actual speed through anti-aliasing by formula (8) specifically when the actually measured speed exceeds these two values. For example, when the current actual speed is: v = 0.5 m / s, then due to aliasing, the obtained B1 and B2 are respectively:

[0073] B1 = 0.5 - 2×0.231 = 0.038 m / s

[0074] B2 = 0.5 - 2×0.308 = -0.116 m / s

[0075] Substitute B1 and B2, v max1 and v max2 all into formula (8):

[0076]

[0077] Let |(0.038 + 0.116) - 2(0.308N - 0.231M)| be X. The following shows X corresponding to different M and N through Table 1:

[0078] Table 1

[0079] M N X 0 0 0.154 1 0 0.616 1 1 0 -1 0 -0.308 -1 -1 0.308 -2 -1 -0.154 -2 -2 0.462 2 1 0.462 2 2 -0.154 3 2 0.308 3 3 -0.308 4 3 0.154 4 4 -0.462 5 4 0 5 5 -0.616 6 5 -0.154 6 6 0.77

[0080] It can be seen from the values in Table 1 that when both M and N are 1 and when M = 5, N = 4, the smallest X is obtained. Take the M with a relatively smaller absolute value. Substitute M = 1 into formula (3) to obtain the final value:

[0081]

[0082] It is not difficult to see that the speed value measured by this method is the same as the actual speed value, which proves that the method of this application can accurately measure the projection component of the blood flow speed at a certain emission angle, and thus can accurately measure the blood flow speed vector.

[0083] In another example, assume that the first pulse repetition frequency is 2k (i.e., 2000 Hz), the second pulse repetition frequency is 9k (i.e., 9000 Hz), when the speed of sound c is 1540 m / s and the center frequency of the probe transmitting signal is 4 MHz, the maximum measurable speeds (taking the absolute value) corresponding to the first pulse repetition frequency and the second pulse repetition frequency are respectively:

[0084]

[0085]

[0086] The following describes how to de-alias the actual speed through formula (8) when the measured actual speed exceeds these two values. For example, when the current actual speed is: v = -1 m / s, then due to aliasing, the obtained B1 and B2 are respectively:

[0087] B1 = -1 + 3×2×0.1925 = 0.155 m / s

[0088] B2 = -1 + 2×0.86625 = 0.7325 m / s

[0089] Substitute B1 and B2, v max1 and v max2 all into formula (8):

[0090]

[0091] Let |(0.155 - 0.7324) - (0.8662N - 0.1925M)| be X, and the following shows the X corresponding to different M and N through Table 2:

[0092] Table 2

[0093]

[0094]

[0095] It can be seen from the values in Table 2 that when M = 6, N = 1, M = -3, N = -1, and M = -12, N = -3, the minimum X is obtained. Take the M with a relatively small absolute value, and substitute M = -3 into formula (3) to obtain the final value:

[0096]

[0097] In this example, it can also be seen that the speed value measured by this method is the same as the actual speed value, which proves that the method of the present application can accurately measure the projection component of the blood flow speed at a certain emission angle, and thus can accurately measure the blood flow speed vector.

[0098] In another example, assuming that the first pulse repetition frequency is 3.5k (i.e., 3500 Hz), the second pulse repetition frequency is 2k (i.e., 2000 Hz), when the speed of sound c is 1540 m / s and the center frequency of the probe transmitting signal is 5 MHz, the maximum measurable speeds (taking the absolute value) corresponding to the first pulse repetition frequency and the second pulse repetition frequency are respectively:

[0099]

[0100]

[0101] The following describes how to de-alias to obtain the actual speed through formula (8) when the measured actual speed exceeds these two values. For example, when the current actual speed is: v = 1.5 m / s, then due to aliasing, the obtained B1 and B2 are respectively:

[0102] B1 = 1.5 - 3×2×0.2695 = -0.117 m / s

[0103] B2 = 1.5 - 5×2×0.154 = -0.04 m / s

[0104] Substitute B1 and B2, v max1 and v max2 all into formula (8):

[0105]

[0106] Let |(-0.117 + 0.04) - 2(0.154N - 0.2695M)| be X, and the following shows X corresponding to different M and N through Table 3:

[0107] Table 3

[0108] M N X 0 0 -0.077 0 1 -0.385 1 1 0.154 1 2 -0.154 2 2 0.385 0 2 -0.693 1 3 -0.462 2 3 0.077 3 3 0.616 3 4 0.308 3 5 0 7 12 0 -1 -2 0 -5 -9 0

[0109] It can be seen from the values in Table 3 that when M = 3, N = 5, M = 7, N = 12, M = -1, N = -2, and M = -5, N = -9, the minimum X is obtained. Take the M with a relatively small absolute value, and substitute M = -1 into formula (3) to obtain the final value:

[0110]

[0111] In this example, it can be seen that due to the excessive actual speed, the correct blood flow speed value still cannot be obtained using this method.

[0112] Only by substituting M = 3 into formula (3) can the correct speed value be obtained, that is:

[0113]

[0114] However, in the case where the actual speed is unknown, it is impossible to know which value of M to substitute to obtain the actual speed value. This is the limitation of the non-uniform PRF emission for calculating blood flow speed in this application. However, compared with the traditional method, the maximum measurable speed has been greatly improved.

[0115] Although the first emission angle and the second emission angle are described in the above example, it is only the simplest example. This application aims to obtain the speed component corresponding to each angle (i.e., the projection component in the previous text) by means of multi-angle emission (at least two emission angles), and then perform vector reconstruction based on these speed components to obtain the blood flow velocity vector. In addition, although it is described in the above example that the first emission angle emits the first to the third ultrasonic waves, and the second emission angle emits the fourth to the sixth ultrasonic waves, it is only the simplest example. This application does not limit the number of ultrasonic waves emitted at each emission angle, as long as at least three are satisfied for each emission angle. Additionally, a multi-angle emission combined with multi-angle reception method (i.e., receiving the echo of ultrasonic waves at one or more reception angles) can be adopted to obtain speed components at multiple different angles, and then perform vector reconstruction based on these speed components to obtain the blood flow velocity vector, and image the blood flow velocity vector to achieve vector blood flow imaging.

[0116] In the embodiments of the present application, the first emission angle and the second emission angle can be alternately emitted. In this embodiment, the emission order of the foregoing first ultrasonic wave, second ultrasonic wave, third ultrasonic wave, fourth ultrasonic wave, fifth ultrasonic wave, and sixth ultrasonic wave can be: the first ultrasonic wave, the fourth ultrasonic wave, the second ultrasonic wave, the fifth ultrasonic wave, the third ultrasonic wave, and the sixth ultrasonic wave. The alternate emission of the two emission angles results in a short time interval between different angles, making the synthesized velocity vector more accurate. In other embodiments, the same emission angle can also be continuously emitted. For example, the emission order of the foregoing first ultrasonic wave, second ultrasonic wave, third ultrasonic wave, fourth ultrasonic wave, fifth ultrasonic wave, and sixth ultrasonic wave can be: the first ultrasonic wave, the second ultrasonic wave, the fourth ultrasonic wave, the fifth ultrasonic wave, the third ultrasonic wave, and the sixth ultrasonic wave; or the first ultrasonic wave, the second ultrasonic wave, the third ultrasonic wave, the fourth ultrasonic wave, the fifth ultrasonic wave, and the sixth ultrasonic wave. In other embodiments, the emission order of the foregoing first ultrasonic wave, second ultrasonic wave, third ultrasonic wave, fourth ultrasonic wave, fifth ultrasonic wave, and sixth ultrasonic wave can also be: the first ultrasonic wave, the fourth ultrasonic wave, the fifth ultrasonic wave, the second ultrasonic wave, the third ultrasonic wave, and the sixth ultrasonic wave; or the first ultrasonic wave, the second ultrasonic wave, the fourth ultrasonic wave, the third ultrasonic wave, the fifth ultrasonic wave, and the sixth ultrasonic wave; or the first ultrasonic wave, the second ultrasonic wave, the fourth ultrasonic wave, the fifth ultrasonic wave, the sixth ultrasonic wave, and the third ultrasonic wave; or the first ultrasonic wave, the fourth ultrasonic wave, the second ultrasonic wave, the third ultrasonic wave, the fifth ultrasonic wave, and the sixth ultrasonic wave; or the first ultrasonic wave, the fourth ultrasonic wave, the fifth ultrasonic wave, the sixth ultrasonic wave, the second ultrasonic wave, and the third ultrasonic wave; or the first ultrasonic wave, the fourth ultrasonic wave, the second ultrasonic wave, the fifth ultrasonic wave, the sixth ultrasonic wave, and the third ultrasonic wave; or the first ultrasonic wave, the fourth ultrasonic wave, the fifth ultrasonic wave, the second ultrasonic wave, the sixth ultrasonic wave, and the third ultrasonic wave. The following will be described exemplarily in conjunction with Figure 2 for illustration.

[0117] Figure 2 FIG. shows an exemplary schematic diagram of emitting ultrasonic waves in an ultrasonic blood flow imaging method according to an embodiment of the present application. As Figure 2 shown, in the Figure 2 example, taking two emission angles as an example, the arrow pointing to the left is the first emission angle, and the arrow pointing to the right is the second emission angle. Among them, the two PRFs corresponding to the first emission angle are 6k and 5k respectively, and the two PRFs corresponding to the second emission angle are also 6k and 5k respectively. In this example, when c is 1540 m / s and the center frequency of the probe emission signal is 3 MHz, the maximum measurable speed by the traditional method is (taking the absolute value, when PRF = 6k):

[0118]

[0119] And the maximum measurable speed corresponding to the method of the present application is:

[0120]

[0121] Obviously, the method of the present application can increase the maximum measurable speed. The pulse repetition frequency used to obtain the maximum measurable speed according to the method of the present application is the least common multiple of two PRFs (i.e., 6k and 5k). Therefore, the first pulse repetition frequency and the second pulse repetition frequency described above are not in an integer multiple relationship, and the third pulse repetition frequency and the fourth pulse repetition frequency are not in an integer multiple relationship, otherwise it is impossible to increase the maximum measurable speed. In addition, it can also be seen that when the first pulse repetition frequency and the second pulse repetition frequency are relatively prime to each other, the maximum measurable speed at the first emission angle can be increased to the greatest extent. Similarly, when the third pulse repetition frequency and the fourth pulse repetition frequency are relatively prime to each other, the maximum measurable speed at the second emission angle can be increased to the greatest extent.

[0122] In an embodiment of the present application, the reciprocal of the maximum value among the first pulse repetition frequency, the second pulse repetition frequency, the third pulse repetition frequency, and the fourth pulse repetition frequency is greater than twice the ratio of the blood flow imaging depth to the sound speed of the ultrasonic wave propagating in the blood flow to be measured. The reciprocal of each pulse repetition frequency corresponds to the time interval between two ultrasonic wave emissions. Therefore, the reciprocal of the maximum value among the first pulse repetition frequency, the second pulse repetition frequency, the third pulse repetition frequency, and the fourth pulse repetition frequency being greater than twice the ratio of the blood flow imaging depth to the sound speed of the ultrasonic wave propagating in the blood flow to be measured means that: the minimum emission time interval is greater than twice the ratio of the blood flow imaging depth to the sound speed of the ultrasonic wave propagating in the blood flow to be measured, which can ensure that all the emitted ultrasonic waves can be received.

[0123] In an embodiment of the present application, the first pulse repetition frequency may be the same as the third pulse repetition frequency, and the second pulse repetition frequency may be the same as the fourth pulse repetition frequency.

[0124] For high-frame-rate vector blood flow imaging, the scanning of blood flow imaging is usually a non-focused wave, for example, a plane wave or a diverging wave, etc. After such a single scan, the entire image can be obtained through beam synthesis signal processing. However, the image quality of the traditional grayscale image needs to be ensured while performing blood flow imaging. In order to have sufficient spatial resolution for the grayscale image, focused waves are usually required for emission. Thus, it is necessary to alternately emit and scan focused waves and non-focused waves to simultaneously achieve high-frame-rate blood flow imaging and high-spatial-resolution grayscale B-mode imaging.

[0125] Based on this, in an embodiment of the present application, the foregoing first ultrasonic wave, second ultrasonic wave, third ultrasonic wave, fourth ultrasonic wave, fifth ultrasonic wave, and sixth ultrasonic wave may all be non-focused ultrasonic waves. Method 100 may further include (not shown): emitting a focused ultrasonic wave to a blood flow position to be measured, receiving the echo of the focused ultrasonic wave to obtain a focused echo signal; generating a grayscale image of the blood flow position to be measured based on the focused echo signal; generating a blood flow velocity vector map based on the blood flow velocity vector of the blood flow position to be measured; and displaying the grayscale image and superimposing and displaying the blood flow velocity vector map on the grayscale image.

[0126] Wherein, the focused ultrasonic wave may be emitted between any two adjacent ones of the first ultrasonic wave, second ultrasonic wave, third ultrasonic wave, fourth ultrasonic wave, fifth ultrasonic wave, and sixth ultrasonic wave. For example, the reciprocal of the minimum value among the first pulse repetition frequency, second pulse repetition frequency, third pulse repetition frequency, and fourth pulse repetition frequency is the maximum emission time interval, and the focused ultrasonic wave may be emitted between the two ultrasonic waves corresponding to the maximum emission time interval.

[0127] The following Figure 3 exemplarily illustrates the alternating scanning of the focused wave and non-focused wave. As Figure 3 shown, the non-focused wave is used for blood flow imaging (diagonal lines with arrows), and there are two different emission angles. Each emission angle corresponds to two different emission PRFs, which are 7k and 3k respectively. The focused wave is used for grayscale B-mode imaging (vertical lines without arrows). In this example, when the sound speed c is 1540 m / s and the center frequency of the probe emission signal is 3 MHz, the maximum measurable speed of the traditional method is (taking the absolute value, when PRF = 7k):

[0128]

[0129] And the maximum measurable speed corresponding to the method of the present application is:

[0130]

[0131] At the same time, the scanning depth is similar to that of the traditional vector blood flow imaging (when PRF = 7k) and is not affected. Because the minimum time interval between two adjacent emissions remains unchanged, which is the reciprocal of 14k.

[0132] In an embodiment of the present application, method 100 may further include: in an echo signal sequence composed of a first echo signal, a second echo signal, a third echo signal, a fourth echo signal, a fifth echo signal, and a sixth echo signal, echo signals having the same transmission angle and the same transmission time interval between each other are used as a group of signals, at least two groups of echo signals are obtained, and wall filtering is performed on each group of echo signals respectively. The echo signals obtained after wall filtering are used to calculate a first blood flow velocity, a second blood flow velocity, a third blood flow velocity, and a fourth blood flow velocity.

[0133] Wall filtering is to filter the signal to filter out stationary tissues and obtain the signal of moving blood flow. Wall filtering is generally high-pass filtering. Traditional wall filtering includes FIR or IIR filters. However, the input signals of these two filters are generally equidistant signals. The present application uses a non-uniform transmission PRF, that is, the time intervals between two adjacent transmissions or two adjacent transmissions at the same angle at different times are all different. The following will be described in conjunction with Figure 4 and Figure 5 to describe.

[0134] Figure 4 FIG. shows an example diagram of grouping the transmitted ultrasonic waves in the ultrasonic blood flow imaging method according to an embodiment of the present application to perform wall filtering on their respective echo signals. As shown in the upper diagram of Figure 4 , two transmission angles both use two PRFs, which are 6k and 5k respectively, and the time intervals between two adjacent transmissions or two adjacent transmissions at the same angle at different times are all different. Therefore, in order to ensure the normal use of wall filtering, wall filtering will be performed in the following manner: echo signals having the same transmission angle and the same transmission time interval between each other are used as a group of signals, at least two groups of echo signals are obtained, and wall filtering is performed on each group of echo signals respectively. As shown in the lower diagram of Figure 4 , different colors are used to distinguish different groups of signals, and signals of the same color (i.e., echo signals having the same transmission angle and the same transmission time interval between each other) are used as a group of signals for wall filtering.

[0135] Figure 5 FIG. shows another example diagram of grouping the transmitted ultrasonic waves in the ultrasonic blood flow imaging method according to an embodiment of the present application to perform wall filtering on their respective echo signals. As shown in the upper diagram of Figure 5 , two transmission angles both use two PRFs, which are 7k and 3k respectively, and focused waves for gray-scale imaging are also transmitted during the non-focused wave transmission interval. And Figure 4Similarly, the time intervals between two adjacent transmissions or between two adjacent transmissions at the same angle at different times are all different. Therefore, to ensure normal use of wall filtering, wall filtering will be performed in the following manner: Echo signals with the same transmission angle and the same transmission time interval between each other are grouped as a set of signals, at least two sets of echo signals are obtained, and wall filtering is performed on each set of echo signals separately. As shown in the following figure of Figure 5 , signals of different groups are distinguished by different colors, and signals of the same color (i.e., echo signals with the same transmission angle and the same transmission time interval between each other) are grouped as a set of signals for wall filtering.

[0136] Figures 2 to 5 Only the example where the ultrasonic wave with the same PRF in the same transmission angle is transmitted once is taken as an illustration, and the number of transmissions is not limited. In the actual process, the ultrasonic wave with the same PRF in the same transmission angle can also be continuously transmitted multiple times. For example, at least one of the aforementioned first ultrasonic wave to the sixth ultrasonic wave can be continuously transmitted multiple times, that is, the ultrasonic wave with the same PRF in the same transmission angle can be continuously transmitted once or multiple times. As shown in Figure 6 , it shows the case where the same PRF at the same angle is continuously transmitted 6 times.

[0137] In the embodiment of the present application, the calculation of the three-dimensional velocity vector can also be performed. Method 100 may further include: transmitting the seventh ultrasonic wave, the eighth ultrasonic wave, and the ninth ultrasonic wave to the position of the blood flow to be measured at a third transmission angle different from the first transmission angle and the second transmission angle, and receiving the echoes of the ultrasonic waves to obtain the seventh echo signal, the eighth echo signal, and the ninth echo signal; wherein, there is a fifth pulse repetition frequency between the seventh ultrasonic wave and the eighth ultrasonic wave, and there is a sixth pulse repetition frequency between the eighth ultrasonic wave and the ninth ultrasonic wave, and the fifth pulse repetition frequency and the sixth pulse repetition frequency are not in an integer multiple relationship; according to the seventh echo signal, the eighth echo signal, the ninth echo signal, the fifth pulse repetition frequency, and the sixth pulse repetition frequency, the third projection component of the blood flow velocity vector at the position of the blood flow to be measured on the third transmission angle is obtained; synthesizing the first projection component and the second projection component to obtain the blood flow velocity vector at the position of the blood flow to be measured, including: synthesizing the first projection component, the second projection component, and the third projection component to obtain the three-dimensional blood flow velocity vector at the position of the blood flow to be measured. This embodiment adds another transmission angle on the basis of method 100. The relevant description can be understood with reference to the aforementioned steps S110-S150, and will not be elaborated here.

[0138] The ultrasonic blood flow imaging method 100 according to an embodiment of the present application is exemplarily shown above. Based on the above description, the ultrasonic blood flow imaging method 100 according to an embodiment of the present application emits ultrasonic waves to the blood flow position to be measured of the target object at at least two transmission angles, and each transmission angle emits ultrasonic waves using a non-uniform PRF, which can achieve a larger actual PRF, thereby increasing the maximum measurable speed, and further improving the measurement accuracy of the blood flow velocity vector at the blood flow position to be measured.

[0139] The following Figure 7 describes a schematic flowchart of an ultrasonic blood flow imaging method 700 according to another embodiment of the present application. As Figure 7 shown, the ultrasonic blood flow imaging method 700 may include the following steps:

[0140] In step S710, first ultrasonic wave, second ultrasonic wave, third ultrasonic wave and fourth ultrasonic wave are emitted to the blood flow position to be measured of the target object at a first transmission angle, and the echoes of the ultrasonic waves are received to obtain a first echo signal, a second echo signal, a third echo signal and a fourth echo signal; wherein, there is a first pulse repetition frequency between the first ultrasonic wave and the second ultrasonic wave, and there is a second pulse repetition frequency between the third ultrasonic wave and the fourth ultrasonic wave, and the first pulse repetition frequency and the second pulse repetition frequency are not in an integer multiple relationship.

[0141] In step S720, fifth ultrasonic wave, sixth ultrasonic wave, seventh ultrasonic wave and eighth ultrasonic wave are emitted to the blood flow position to be measured at a second transmission angle different from the first transmission angle, and the echoes of the ultrasonic waves are received to obtain a fifth echo signal, a sixth echo signal, a seventh echo signal and an eighth echo signal; wherein, there is a third pulse repetition frequency between the fifth ultrasonic wave and the sixth ultrasonic wave, and there is a fourth pulse repetition frequency between the seventh ultrasonic wave and the eighth ultrasonic wave, and the third pulse repetition frequency and the fourth pulse repetition frequency are not in an integer multiple relationship.

[0142] In step S730, according to the first echo signal, the second echo signal, the third echo signal, the fourth echo signal, the first pulse repetition frequency and the second pulse repetition frequency, a first projection component of the blood flow velocity vector at the blood flow position to be measured on the first transmission angle is obtained.

[0143] In step S740, according to the fifth echo signal, the sixth echo signal, the seventh echo signal, the eighth echo signal, the third pulse repetition frequency and the fourth pulse repetition frequency, a second projection component of the blood flow velocity vector at the blood flow position to be measured on the second transmission angle is obtained.

[0144] In step S750, the first projection component and the second projection component are synthesized to obtain the blood flow velocity vector at the blood flow position to be measured.

[0145] The ultrasonic blood flow imaging method 700 according to the embodiments of the present application is generally similar to the ultrasonic blood flow imaging method 100 described above. The difference lies in that: the ultrasonic blood flow imaging method 100 controls all adjacent two ultrasonic waves at the same emission angle with two different PRFs (i.e., there is a first PRF between the first ultrasonic wave and the second ultrasonic wave, and a second PRF between the second ultrasonic wave and the third ultrasonic wave); in contrast, the ultrasonic blood flow imaging method 700 controls some adjacent two ultrasonic waves at the same emission angle with two different PRFs (i.e., there is a first PRF between the first ultrasonic wave and the second ultrasonic wave, and a second PRF between the third ultrasonic wave and the fourth ultrasonic wave, and the PRF between the second ultrasonic wave and the third ultrasonic wave is not limited). Based on this, the ultrasonic blood flow imaging method 100 needs to reuse the ultrasonic echo signal when calculating the blood flow velocity (i.e., obtaining the first blood flow velocity according to the first echo signal and the second echo signal, and obtaining the second blood flow velocity according to the second echo signal and the third echo signal, that is, reusing the second echo signal), while the ultrasonic blood flow imaging method 700 does not need to reuse the ultrasonic echo signal when calculating the blood flow velocity (i.e., obtaining the first blood flow velocity according to the first echo signal and the second echo signal, and obtaining the second blood flow velocity according to the third echo signal and the fourth echo signal). For the sake of brevity, the similarities between the two are not described in detail here. The details of the ultrasonic blood flow imaging method 700 can be understood in combination with the above description, and only its main operations are briefly described here.

[0146] In the embodiments of the present application, obtaining the first projection component of the blood flow velocity vector of the blood flow position to be measured on the first emission angle according to the first echo signal, the second echo signal, the third echo signal, the fourth echo signal, the first pulse repetition frequency, and the second pulse repetition frequency in step S730 may include: obtaining the first blood flow velocity according to the first echo signal and the second echo signal, and obtaining the second blood flow velocity according to the third echo signal and the fourth echo signal; obtaining the first maximum measurable velocity corresponding to the first pulse repetition frequency and the second maximum measurable velocity corresponding to the second pulse repetition frequency; determining a first de-aliasing coefficient that satisfies a first preset condition according to the first blood flow velocity, the second blood flow velocity, the first maximum measurable velocity, and the second maximum measurable velocity; and performing de-aliasing processing on the first blood flow velocity and / or the second blood flow velocity based on the first de-aliasing coefficient to obtain the first projection component of the blood flow velocity vector of the blood flow position to be measured on the first emission angle.

[0147] Among them, determining the first dealiasing coefficient that meets the first preset condition according to the first blood flow velocity, the second blood flow velocity, the first maximum measurable velocity, and the second maximum measurable velocity may include: taking the difference between the first blood flow velocity and the second blood flow velocity as the first difference; taking twice the difference between N times the second maximum measurable velocity and M times the first maximum measurable velocity as the second difference, where both N and M are integers; taking the difference between the first difference and the second difference as the third difference; calculating the value results of M and N that minimize the absolute value of the third difference, and taking M and / or N in the value results as the first dealiasing coefficient; among them, when the value result of M is used as the first dealiasing coefficient, dealiasing the first blood flow velocity based on the first dealiasing coefficient to obtain the first projection component of the blood flow velocity vector at the first emission angle at the blood flow position to be measured; when the value result of N is used as the first dealiasing coefficient, dealiasing the second blood flow velocity based on the first dealiasing coefficient to obtain the first projection component of the blood flow velocity vector at the first emission angle at the blood flow position to be measured. It is also possible to average the projection component obtained by dealiasing the first blood flow velocity with M as the first dealiasing coefficient and the projection component obtained by dealiasing the first blood flow velocity with N as the first dealiasing coefficient, and take the averaged result as the first projection component of the blood flow velocity vector at the blood flow position to be measured at the first emission angle.

[0148] Among them, when there are at least two groups of value results of M and N that minimize the absolute value of the third difference, take M and / or N with the smallest absolute value in the value results as the first dealiasing coefficient.

[0149] In an embodiment of the present application, obtaining the second projection component of the blood flow velocity vector at the second emission angle at the blood flow position to be measured according to the fifth echo signal, the sixth echo signal, the seventh echo signal, the eighth echo signal, the third pulse repetition frequency, and the fourth pulse repetition frequency in step S740 may include: obtaining the third blood flow velocity according to the fifth echo signal and the sixth echo signal, and obtaining the fourth blood flow velocity according to the seventh echo signal and the eighth echo signal; obtaining the third maximum measurable velocity corresponding to the third pulse repetition frequency and the fourth maximum measurable velocity corresponding to the fourth pulse repetition frequency; determining the second dealiasing coefficient that meets the second preset condition according to the third blood flow velocity, the fourth blood flow velocity, the third maximum measurable velocity, and the fourth maximum measurable velocity; dealiasing the third blood flow velocity and / or the fourth blood flow velocity based on the second dealiasing coefficient to obtain the second projection component of the blood flow velocity vector at the second emission angle at the blood flow position to be measured.

[0150] Among them, determining the second de-aliasing coefficient that meets the second preset condition according to the third blood flow velocity, the fourth blood flow velocity, the third maximum measurable velocity, and the fourth maximum measurable velocity may include: taking the difference between the third blood flow velocity and the fourth blood flow velocity as the fourth difference; taking twice the difference between N times the third maximum measurable velocity and M times the fourth maximum measurable velocity as the fifth difference, where both N and M are integers; taking the difference between the fourth difference and the fifth difference as the sixth difference; calculating the values of M and N that minimize the absolute value of the sixth difference, and taking M and / or N in the value result as the second de-aliasing coefficient; among them, when the value result of M is used as the second de-aliasing coefficient, de-aliasing processing is performed on the third blood flow velocity based on the second de-aliasing coefficient to obtain the second projection component of the blood flow velocity vector at the position of the blood flow to be measured at the second emission angle; when the value result of N is used as the second de-aliasing coefficient, de-aliasing processing is performed on the fourth blood flow velocity based on the second de-aliasing coefficient to obtain the second projection component of the blood flow velocity vector at the position of the blood flow to be measured at the second emission angle. It is also possible to average the projection component obtained by performing de-aliasing processing on the third blood flow velocity with M as the second de-aliasing coefficient and the projection component obtained by performing de-aliasing processing on the fourth blood flow velocity with N as the second de-aliasing coefficient, and taking the averaged result as the second projection component of the blood flow velocity vector at the position of the blood flow to be measured at the second emission angle.

[0151] Among them, when there are at least two sets of value results of M and N such that the absolute value of the sixth difference is minimized, M and / or N with the smallest absolute value in the value result is taken as the second de-aliasing coefficient.

[0152] In the embodiments of the present application, the emission order of the first ultrasonic wave, the second ultrasonic wave, the third ultrasonic wave, the fourth ultrasonic wave, the fifth ultrasonic wave, the sixth ultrasonic wave, the seventh ultrasonic wave, and the eighth ultrasonic wave may be: the first ultrasonic wave, the fifth ultrasonic wave, the second ultrasonic wave, the sixth ultrasonic wave, the third ultrasonic wave, the seventh ultrasonic wave, the fourth ultrasonic wave, the eighth ultrasonic wave; or the first ultrasonic wave, the second ultrasonic wave, the fifth ultrasonic wave, the sixth ultrasonic wave, the third ultrasonic wave, the fourth ultrasonic wave, the seventh ultrasonic wave, the eighth ultrasonic wave; or the first ultrasonic wave, the second ultrasonic wave, the third ultrasonic wave, the fifth ultrasonic wave, the sixth ultrasonic wave, the seventh ultrasonic wave, the fourth ultrasonic wave, the eighth ultrasonic wave; or the first ultrasonic wave, the second ultrasonic wave, the third ultrasonic wave, the fourth ultrasonic wave, the fifth ultrasonic wave, the sixth ultrasonic wave, the seventh ultrasonic wave, the eighth ultrasonic wave. Similarly, referring to the description of the alternating scanning order in the foregoing embodiments, the emission order of the first to eighth ultrasonic waves in the embodiments of the present application is not limited to the several listed above, and only needs to achieve an alternating effect, and will not be enumerated here.

[0153] In an embodiment of the present application, the first pulse repetition frequency and the second pulse repetition frequency are relatively prime to each other, and the third pulse repetition frequency and the fourth pulse repetition frequency are relatively prime to each other.

[0154] In an embodiment of the present application, the reciprocal of the maximum value among the first pulse repetition frequency, the second pulse repetition frequency, the third pulse repetition frequency, and the fourth pulse repetition frequency is greater than twice the ratio of the blood flow imaging depth to the sound velocity of the ultrasonic wave propagating in the blood flow to be measured.

[0155] In an embodiment of the present application, the first pulse repetition frequency may be the same as the third pulse repetition frequency, and the second pulse repetition frequency may be the same as the fourth pulse repetition frequency.

[0156] In an embodiment of the present application, receiving the echo of the ultrasonic wave may include: receiving the echo of the ultrasonic wave at one or more reception angles.

[0157] In an embodiment of the present application, the first ultrasonic wave, the second ultrasonic wave, the third ultrasonic wave, the fourth ultrasonic wave, the fifth ultrasonic wave, the sixth ultrasonic wave, the seventh ultrasonic wave, and the eighth ultrasonic wave may all be non-focused ultrasonic waves. The method 700 may further include (not shown): emitting a focused ultrasonic wave to the position of the blood flow to be measured, receiving the echo of the focused ultrasonic wave to obtain a focused echo signal; generating a grayscale image of the position of the blood flow to be measured based on the focused echo signal; generating a blood flow velocity vector map based on the blood flow velocity vector of the position of the blood flow to be measured; and displaying the grayscale image and superimposing and displaying the blood flow velocity vector map on the grayscale image.

[0158] In an embodiment of the present application, the focused ultrasonic wave may be emitted between any two adjacent ones of the first ultrasonic wave, the second ultrasonic wave, the third ultrasonic wave, the fourth ultrasonic wave, the fifth ultrasonic wave, the sixth ultrasonic wave, the seventh ultrasonic wave, and the eighth ultrasonic wave.

[0159] In an embodiment of the present application, the reciprocal of the minimum value among the first pulse repetition frequency, the second pulse repetition frequency, the third pulse repetition frequency, and the fourth pulse repetition frequency is the maximum emission time interval, and the focused ultrasonic wave may be emitted between the two ultrasonic waves corresponding to the maximum emission time interval.

[0160] In an embodiment of the present application, the method 700 may further include (not shown): in the echo signal sequence composed of the first echo signal, the second echo signal, the third echo signal, the fourth echo signal, the fifth echo signal, the sixth echo signal, the seventh echo signal, and the eighth echo signal, regarding the echo signals having the same emission angle and the same emission time interval between them as a group of signals, obtaining at least two groups of echo signals, and respectively performing wall filtering on each group of echo signals. The echo signals obtained after the wall filtering are used to calculate the first blood flow velocity, the second blood flow velocity, the third blood flow velocity, and the fourth blood flow velocity.

[0161] In an embodiment of the present application, the calculation of the three-dimensional velocity vector can also be performed. The method 700 may further include: emitting the ninth ultrasonic wave, the tenth ultrasonic wave, the eleventh ultrasonic wave, and the twelfth ultrasonic wave to the blood flow position to be measured at a third emission angle different from the first emission angle and the second emission angle, and receiving the echoes of the ultrasonic waves to obtain the ninth echo signal, the tenth echo signal, the eleventh echo signal, and the twelfth echo signal; wherein, there is a fifth pulse repetition frequency between the ninth ultrasonic wave and the tenth ultrasonic wave, and there is a sixth pulse repetition frequency between the eleventh ultrasonic wave and the twelfth ultrasonic wave, and the fifth pulse repetition frequency and the sixth pulse repetition frequency are not in an integer multiple relationship; according to the ninth echo signal, the tenth echo signal, the eleventh echo signal, the twelfth echo signal, the fifth pulse repetition frequency, and the sixth pulse repetition frequency, obtaining a third projection component of the blood flow velocity vector at the blood flow position to be measured on the third emission angle; synthesizing the first projection component and the second projection component to obtain the blood flow velocity vector at the blood flow position to be measured, including: synthesizing the first projection component, the second projection component, and the third projection component to obtain the three-dimensional blood flow velocity vector at the blood flow position to be measured. This embodiment adds another emission angle on the basis of the method 700. For relevant descriptions, reference can be made to the foregoing steps S710 to S750 for understanding, and details are not elaborated here.

[0162] Method 100 and method 700 can also be used in combination. In an embodiment of the present application, the ultrasonic blood flow imaging method may include: transmitting a first ultrasonic wave, a second ultrasonic wave, and a third ultrasonic wave at a first emission angle to a blood flow position to be measured of a target object, and receiving the echoes of the ultrasonic waves to obtain a first echo signal, a second echo signal, and a third echo signal; wherein, there is a first pulse repetition frequency between the first ultrasonic wave and the second ultrasonic wave, and a second pulse repetition frequency between the second ultrasonic wave and the third ultrasonic wave, and the first pulse repetition frequency and the second pulse repetition frequency are not in an integer multiple relationship; transmitting a fourth ultrasonic wave, a fifth ultrasonic wave, a sixth ultrasonic wave, and a seventh ultrasonic wave at a second emission angle different from the first emission angle to the blood flow position to be measured, and receiving the echoes of the ultrasonic waves to obtain a fourth echo signal, a fifth echo signal, a sixth echo signal, and a seventh echo signal; wherein, there is a third pulse repetition frequency between the fourth ultrasonic wave and the fifth ultrasonic wave, and a fourth pulse repetition frequency between the sixth ultrasonic wave and the seventh ultrasonic wave, and the third pulse repetition frequency and the fourth pulse repetition frequency are not in an integer multiple relationship; obtaining a first projection component of the blood flow velocity vector at the blood flow position to be measured on the first emission angle according to the first echo signal, the second echo signal, the third echo signal, the first pulse repetition frequency, and the second pulse repetition frequency; obtaining a second projection component of the blood flow velocity vector at the blood flow position to be measured on the second emission angle according to the fourth echo signal, the fifth echo signal, the sixth echo signal, the seventh echo signal, the third pulse repetition frequency, and the fourth pulse repetition frequency; and synthesizing the first projection component and the second projection component to obtain the blood flow velocity vector at the blood flow position to be measured.

[0163] The first emission angle in the ultrasonic blood flow imaging method of the embodiment of the present application adopts a scheme corresponding to the first emission angle in the ultrasonic blood flow imaging method 100 described above, and the second emission angle adopts a scheme corresponding to the second emission angle in the ultrasonic blood flow imaging method 700 described above. The relevant descriptions can be understood by referring to the content in the foregoing method 100 and method 700, and will not be elaborated here.

[0164] The following will be combined with Figure 8 Describe the ultrasonic imaging device 800 according to an embodiment of the present application, the ultrasonic imaging device 800. As Figure 8As shown, the ultrasonic imaging device 800 includes an ultrasonic probe 810, a transmitting circuit 820, a receiving circuit 830, and a processor 840, where: the transmitting circuit 820 is configured to control the ultrasonic probe 810 to transmit ultrasonic waves to the position of the blood flow to be measured of the target object; the receiving circuit 830 is configured to control the ultrasonic probe 810 to receive the echoes of the ultrasonic waves and obtain echo signals from the echoes of the ultrasonic waves; the processor 840 is configured to perform ultrasonic blood flow imaging based on the echo signals; the processor 840 is further configured to execute the ultrasonic blood flow imaging method 100 or 700 according to the embodiments of the present application described above. The structure and operation of the ultrasonic imaging device 800 can be understood in combination with the foregoing description. For the sake of brevity, it will not be elaborated here.

[0165] Based on the above description, the ultrasonic blood flow imaging method and device according to the embodiments of the present application transmit ultrasonic waves to the position of the blood flow to be measured of the target object at at least two transmission angles, and each transmission angle transmits ultrasonic waves using a non-uniform PRF, which can achieve a larger actual PRF, thereby increasing the maximum measurable speed, and further improving the measurement accuracy of the blood flow velocity vector at the position of the blood flow to be measured.

[0166] Although example embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above example embodiments are merely exemplary and are not intended to limit the scope of the present application. Those of ordinary skill in the art can make various changes and modifications therein without departing from the scope and spirit of the present application. All such changes and modifications are intended to be included within the scope of the present application as claimed in the appended claims.

[0167] Those of ordinary skill in the art can realize that the units and algorithm steps of the examples described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Skilled artisans can use different methods for each specific application to implement the described functions, but such implementation should not be considered to exceed the scope of the present application.

[0168] In several embodiments provided by the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division, and there may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed.

[0169] In the specification provided herein, numerous specific details are set forth. However, it will be understood that embodiments of the present application may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0170] Similarly, it should be understood that, in order to streamline the present application and assist in understanding one or more of the various inventive aspects, in the description of the exemplary embodiments of the present application, the various features of the present application are sometimes grouped together in a single embodiment, figure, or description thereof. However, the methods of the present application should not be construed as reflecting an intention that the claimed present application requires more features than are expressly recited in each claim. Rather, as reflected by the corresponding claims, the inventive point lies in that the corresponding technical problems can be solved by features that are less than all the features of a single disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of the present application.

[0171] Those skilled in the art will understand that, except where features are mutually exclusive, any combination can be employed of all the features disclosed in this specification (including the accompanying claims, abstract and drawings), as well as of all the processes or units of any method or device so disclosed. Each feature disclosed in this specification (including the accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise.

[0172] In addition, those skilled in the art will appreciate that, although some embodiments described herein include certain features included in other embodiments but not others, combinations of features of different embodiments are meant to be within the scope of the present application and form different embodiments. For example, in the claims, any one of the claimed embodiments can be used in any combination.

[0173] Each component embodiment of the present application can be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. Those skilled in the art should understand that a microprocessor or a digital signal processor (DSP) can be used in practice to implement some or all of the functions of some modules in the article analysis device according to the embodiments of the present application. The present application can also be implemented as an ultrasonic imaging device program (for example, a computer program and a computer program product) for executing part or all of the methods described herein. Such a program for implementing the present application can be stored on a computer-readable medium, or can be in the form of one or more signals. Such signals can be downloaded from an Internet website, or provided on a carrier signal, or provided in any other form.

[0174] It should be noted that the above embodiments illustrate the present application rather than limit the present application, and those skilled in the art can design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The present application can be implemented by means of hardware including several different elements and by means of a suitably programmed computer. In the unit claims listing several ultrasonic imaging devices, several of these ultrasonic imaging devices can be embodied by the same item of hardware. The use of the words first, second, and third, etc. does not denote any order. These words can be interpreted as names.

[0175] As described above, it is only the specific implementation manner of the present application or the description of the specific implementation manner, and the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present application, and all of them should be covered by the protection scope of the present application. The protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. An ultrasonic blood flow imaging method, characterized in that, The method includes: Emitting a first ultrasonic wave, a second ultrasonic wave, and a third ultrasonic wave at a first emission angle to a blood flow position to be measured of a target object, and receiving the echoes of the ultrasonic waves to obtain a first echo signal, a second echo signal, and a third echo signal; wherein, there is a first pulse repetition frequency between the first ultrasonic wave and the second ultrasonic wave, there is a second pulse repetition frequency between the second ultrasonic wave and the third ultrasonic wave, and the first pulse repetition frequency and the second pulse repetition frequency are not in an integer multiple relationship; Emitting a fourth ultrasonic wave, a fifth ultrasonic wave, and a sixth ultrasonic wave at a second emission angle different from the first emission angle to the blood flow position to be measured, and receiving the echoes of the ultrasonic waves to obtain a fourth echo signal, a fifth echo signal, and a sixth echo signal; wherein, there is a third pulse repetition frequency between the fourth ultrasonic wave and the fifth ultrasonic wave, there is a fourth pulse repetition frequency between the fifth ultrasonic wave and the sixth ultrasonic wave, and the third pulse repetition frequency and the fourth pulse repetition frequency are not in an integer multiple relationship; Obtaining a first projection component of the blood flow velocity vector at the blood flow position to be measured on the first emission angle according to the first echo signal, the second echo signal, the third echo signal, the first pulse repetition frequency, and the second pulse repetition frequency; Obtaining a second projection component of the blood flow velocity vector at the blood flow position to be measured on the second emission angle according to the fourth echo signal, the fifth echo signal, the sixth echo signal, the third pulse repetition frequency, and the fourth pulse repetition frequency; Synthesizing the first projection component and the second projection component to obtain the blood flow velocity vector at the blood flow position to be measured; Among them, the obtaining a first projection component of the blood flow velocity vector at the blood flow position to be measured on the first emission angle according to the first echo signal, the second echo signal, the third echo signal, the first pulse repetition frequency, and the second pulse repetition frequency includes: Obtaining a first blood flow velocity according to the first echo signal and the second echo signal, and obtaining a second blood flow velocity according to the second echo signal and the third echo signal; Obtaining a first maximum measurable velocity corresponding to the first pulse repetition frequency and a second maximum measurable velocity corresponding to the second pulse repetition frequency; Determining a first de-aliasing coefficient that satisfies a first preset condition according to the first blood flow velocity, the second blood flow velocity, the first maximum measurable velocity, and the second maximum measurable velocity; Performing de-aliasing processing on the first blood flow velocity and / or the second blood flow velocity based on the first de-aliasing coefficient to obtain a first projection component of the blood flow velocity vector at the blood flow position to be measured on the first emission angle; The obtaining a second projection component of the blood flow velocity vector at the blood flow position to be measured on the second emission angle according to the fourth echo signal, the fifth echo signal, the sixth echo signal, the third pulse repetition frequency, and the fourth pulse repetition frequency includes: Obtain a third blood flow velocity based on the fourth echo signal and the fifth echo signal, and obtain a fourth blood flow velocity based on the fifth echo signal and the sixth echo signal; Obtain a third maximum measurable velocity corresponding to the third pulse repetition frequency and a fourth maximum measurable velocity corresponding to the fourth pulse repetition frequency; Determine a second aliasing removal coefficient that satisfies a second preset condition based on the third blood flow velocity, the fourth blood flow velocity, the third maximum measurable velocity, and the fourth maximum measurable velocity; Perform aliasing removal processing on the third blood flow velocity and / or the fourth blood flow velocity based on the second aliasing removal coefficient to obtain a second projection component of the blood flow velocity vector at the measured blood flow position on the second emission angle.

2. The method according to claim 1, wherein The determining the first aliasing removal coefficient that satisfies the first preset condition based on the first blood flow velocity, the second blood flow velocity, the first maximum measurable velocity, and the second maximum measurable velocity includes: Taking the difference between the first blood flow velocity and the second blood flow velocity as a first difference; Taking twice the difference between N times the second maximum measurable velocity and M times the first maximum measurable velocity as a second difference, where both N and M are integers; Taking the difference between the first difference and the second difference as a third difference; Calculating the value results of M and N that minimize the absolute value of the third difference, and taking M and / or N in the value results as the first aliasing removal coefficient; Wherein, when the value result of M is used as the first aliasing removal coefficient, perform aliasing removal processing on the first blood flow velocity based on the first aliasing removal coefficient to obtain a first projection component of the blood flow velocity vector at the measured blood flow position on the first emission angle; when the value result of N is used as the first aliasing removal coefficient, perform aliasing removal processing on the second blood flow velocity based on the first aliasing removal coefficient to obtain a first projection component of the blood flow velocity vector at the measured blood flow position on the first emission angle; The determining the second aliasing removal coefficient that satisfies the second preset condition based on the third blood flow velocity, the fourth blood flow velocity, the third maximum measurable velocity, and the fourth maximum measurable velocity includes: Taking the difference between the third blood flow velocity and the fourth blood flow velocity as a fourth difference; Taking twice the difference between N times the third maximum measurable velocity and M times the fourth maximum measurable velocity as a fifth difference, where both N and M are integers; Taking the difference between the fourth difference and the fifth difference as a sixth difference; Calculating the value results of M and N that minimize the absolute value of the sixth difference, and taking M and / or N in the value results as the second aliasing removal coefficient; Wherein, when the value of M is used as the second aliasing removal coefficient, the third blood flow velocity is processed for aliasing removal based on the second aliasing removal coefficient to obtain a second projection component of the blood flow velocity vector at the position of the blood flow to be measured on the second emission angle; when the value of N is used as the second aliasing removal coefficient, the fourth blood flow velocity is processed for aliasing removal based on the second aliasing removal coefficient to obtain a second projection component of the blood flow velocity vector at the position of the blood flow to be measured on the second emission angle.

3. The method according to claim 2, wherein when there are at least two sets of value results of M and N such that the absolute value of the third difference obtains a minimum value, the M and / or N with the smallest absolute value in the value results is used as the first aliasing removal coefficient; when there are at least two sets of value results of M and N such that the absolute value of the sixth difference obtains a minimum value, the M and / or N with the smallest absolute value in the value results is used as the second aliasing removal coefficient.

4. The method according to claim 1, wherein The method further includes: In the echo signal sequence composed of the first echo signal, the second echo signal, the third echo signal, the fourth echo signal, the fifth echo signal, and the sixth echo signal, the echo signals with the same emission angle and the same emission time interval between each other are used as a group of signals to obtain at least two groups of echo signals, and each group of echo signals is respectively subjected to wall filtering, and the echo signals obtained after the wall filtering are used to calculate the first blood flow velocity, the second blood flow velocity, the third blood flow velocity, and the fourth blood flow velocity.

5. The method according to claim 1, characterized in that, The emission order of the first ultrasonic wave, the second ultrasonic wave, the third ultrasonic wave, the fourth ultrasonic wave, the fifth ultrasonic wave, and the sixth ultrasonic wave is: the first ultrasonic wave, the fourth ultrasonic wave, the second ultrasonic wave, the fifth ultrasonic wave, the third ultrasonic wave, the sixth ultrasonic wave; or the first ultrasonic wave, the second ultrasonic wave, the fourth ultrasonic wave, the fifth ultrasonic wave, the third ultrasonic wave, the sixth ultrasonic wave; or the first ultrasonic wave, the second ultrasonic wave, the third ultrasonic wave, the fourth ultrasonic wave, the fifth ultrasonic wave, the sixth ultrasonic wave; or the first ultrasonic wave, the fourth ultrasonic wave, the fifth ultrasonic wave, the second ultrasonic wave, the third ultrasonic wave, the sixth ultrasonic wave; or the first ultrasonic wave, the second ultrasonic wave, the fourth ultrasonic wave, the third ultrasonic wave, the fifth ultrasonic wave, the sixth ultrasonic wave; or the first ultrasonic wave, the second ultrasonic wave, the fourth ultrasonic wave, the fifth ultrasonic wave, the sixth ultrasonic wave, the third ultrasonic wave; or the first ultrasonic wave, the fourth ultrasonic wave, the second ultrasonic wave, the third ultrasonic wave, the fifth ultrasonic wave, the sixth ultrasonic wave; or the first ultrasonic wave, the fourth ultrasonic wave, the fifth ultrasonic wave, the sixth ultrasonic wave, the second ultrasonic wave, the third ultrasonic wave; or The first ultrasonic wave, the fourth ultrasonic wave, the second ultrasonic wave, the fifth ultrasonic wave, the sixth ultrasonic wave, the third ultrasonic wave; or The first ultrasonic wave, the fourth ultrasonic wave, the fifth ultrasonic wave, the second ultrasonic wave, the sixth ultrasonic wave, the third ultrasonic wave.

6. The method according to claim 1, wherein The first pulse repetition frequency and the second pulse repetition frequency are relatively prime to each other, and the third pulse repetition frequency and the fourth pulse repetition frequency are relatively prime to each other.

7. The method according to claim 1, wherein The reciprocal of the maximum value among the first pulse repetition frequency, the second pulse repetition frequency, the third pulse repetition frequency, and the fourth pulse repetition frequency is greater than twice the ratio of the blood flow imaging depth to the sound velocity of the ultrasonic wave propagating in the blood flow to be measured.

8. The method according to claim 1, wherein The first pulse repetition frequency is the same as the third pulse repetition frequency, and the second pulse repetition frequency is the same as the fourth pulse repetition frequency.

9. The method according to claim 1, characterized in that Receiving the echo of the ultrasonic wave includes: receiving the echo of the ultrasonic wave at one or more receiving angles.

10. The method according to any one of claims 1-9, characterized in that, The first ultrasonic wave, the second ultrasonic wave, the third ultrasonic wave, the fourth ultrasonic wave, the fifth ultrasonic wave, and the sixth ultrasonic wave are all non-focused ultrasonic waves, and the method further includes: Transmitting a focused ultrasonic wave to the position of the blood flow to be measured, and receiving the echo of the focused ultrasonic wave to obtain a focused echo signal; Generating a grayscale image of the position of the blood flow to be measured based on the focused echo signal; Generating a blood flow velocity vector map based on the blood flow velocity vector of the position of the blood flow to be measured; Displaying the grayscale image and superimposing and displaying the blood flow velocity vector map on the grayscale image.

11. The method according to claim 10, wherein The focused ultrasonic wave is transmitted between any two adjacent ones of the first ultrasonic wave, the second ultrasonic wave, the third ultrasonic wave, the fourth ultrasonic wave, the fifth ultrasonic wave, and the sixth ultrasonic wave.

12. The method according to claim 10, characterized in that, The reciprocal of the minimum value among the first pulse repetition frequency, the second pulse repetition frequency, the third pulse repetition frequency, and the fourth pulse repetition frequency is the maximum emission time interval, and the focused ultrasonic wave is transmitted between the two ultrasonic waves corresponding to the maximum emission time interval.

13. The method according to claim 1, characterized in that, The method further includes: Transmitting a seventh ultrasonic wave, an eighth ultrasonic wave, and a ninth ultrasonic wave to the position of the blood flow to be measured at a third emission angle different from the first emission angle and the second emission angle, and receiving the echo of the ultrasonic wave to obtain a seventh echo signal, an eighth echo signal, and a ninth echo signal; wherein, there is a fifth pulse repetition frequency between the seventh ultrasonic wave and the eighth ultrasonic wave, and there is a sixth pulse repetition frequency between the eighth ultrasonic wave and the ninth ultrasonic wave, and the fifth pulse repetition frequency and the sixth pulse repetition frequency are not in an integer multiple relationship; Obtaining a third projection component of the blood flow velocity vector of the position of the blood flow to be measured on the third emission angle according to the seventh echo signal, the eighth echo signal, the ninth echo signal, the fifth pulse repetition frequency, and the sixth pulse repetition frequency; The synthesizing the first projection component and the second projection component to obtain the blood flow velocity vector of the position of the blood flow to be measured includes: The first projection component, the second projection component, and the third projection component are synthesized to obtain the three-dimensional blood flow velocity vector of the blood flow position to be measured.

14. An ultrasonic blood flow imaging method, characterized in that, The method includes: Emitting first ultrasonic waves, second ultrasonic waves, third ultrasonic waves, and fourth ultrasonic waves at a first emission angle to the blood flow position to be measured of the target object, and receiving the echoes of the ultrasonic waves to obtain a first echo signal, a second echo signal, a third echo signal, and a fourth echo signal; wherein, there is a first pulse repetition frequency between the first ultrasonic wave and the second ultrasonic wave, there is a second pulse repetition frequency between the third ultrasonic wave and the fourth ultrasonic wave, and the first pulse repetition frequency and the second pulse repetition frequency are not in an integer multiple relationship; Emitting fifth ultrasonic waves, sixth ultrasonic waves, seventh ultrasonic waves, and eighth ultrasonic waves at a second emission angle different from the first emission angle to the blood flow position to be measured, and receiving the echoes of the ultrasonic waves to obtain a fifth echo signal, a sixth echo signal, a seventh echo signal, and an eighth echo signal; wherein, there is a third pulse repetition frequency between the fifth ultrasonic wave and the sixth ultrasonic wave, there is a fourth pulse repetition frequency between the seventh ultrasonic wave and the eighth ultrasonic wave, and the third pulse repetition frequency and the fourth pulse repetition frequency are not in an integer multiple relationship; According to the first echo signal, the second echo signal, the third echo signal, the fourth echo signal, the first pulse repetition frequency, and the second pulse repetition frequency, obtaining a first projection component of the blood flow velocity vector of the blood flow position to be measured at the first emission angle; According to the fifth echo signal, the sixth echo signal, the seventh echo signal, the eighth echo signal, the third pulse repetition frequency, and the fourth pulse repetition frequency, obtaining a second projection component of the blood flow velocity vector of the blood flow position to be measured at the second emission angle; The first projection component and the second projection component are synthesized to obtain the blood flow velocity vector of the blood flow position to be measured; Wherein, the obtaining a first projection component of the blood flow velocity vector of the blood flow position to be measured at the first emission angle according to the first echo signal, the second echo signal, the third echo signal, the fourth echo signal, the first pulse repetition frequency, and the second pulse repetition frequency includes: Obtaining a first blood flow velocity according to the first echo signal and the second echo signal, and obtaining a second blood flow velocity according to the third echo signal and the fourth echo signal; Obtaining a first maximum measurable velocity corresponding to the first pulse repetition frequency and a second maximum measurable velocity corresponding to the second pulse repetition frequency; Determining a first de-aliasing coefficient that satisfies a first preset condition according to the first blood flow velocity, the second blood flow velocity, the first maximum measurable velocity, and the second maximum measurable velocity; Based on the first de-aliasing coefficient, performing de-aliasing processing on the first blood flow velocity and / or the second blood flow velocity to obtain a first projection component of the blood flow velocity vector of the blood flow position to be measured at the first emission angle; Obtaining the second projection component of the blood flow velocity vector at the position of the blood flow to be measured on the second emission angle according to the fifth echo signal, the sixth echo signal, the seventh echo signal, the eighth echo signal, the third pulse repetition frequency, and the fourth pulse repetition frequency includes: Obtaining a third blood flow velocity according to the fifth echo signal and the sixth echo signal, and obtaining a fourth blood flow velocity according to the seventh echo signal and the eighth echo signal; Obtaining a third maximum measurable velocity corresponding to the third pulse repetition frequency and a fourth maximum measurable velocity corresponding to the fourth pulse repetition frequency; Determining a second de-aliasing coefficient that satisfies a second preset condition according to the third blood flow velocity, the fourth blood flow velocity, the third maximum measurable velocity, and the fourth maximum measurable velocity; Performing de-aliasing processing on the third blood flow velocity and / or the fourth blood flow velocity based on the second de-aliasing coefficient to obtain the second projection component of the blood flow velocity vector at the position of the blood flow to be measured on the second emission angle.

15. The method according to claim 14, wherein Determining a first de-aliasing coefficient that satisfies a first preset condition according to the first blood flow velocity, the second blood flow velocity, the first maximum measurable velocity, and the second maximum measurable velocity includes: Taking the difference between the first blood flow velocity and the second blood flow velocity as a first difference; Taking twice the difference between N times the second maximum measurable velocity and M times the first maximum measurable velocity as a second difference, where both N and M are integers; Taking the difference between the first difference and the second difference as a third difference; Calculating the value results of M and N that minimize the absolute value of the third difference, and taking M and / or N in the value results as the first de-aliasing coefficient; Wherein, when the value result of M is used as the first de-aliasing coefficient, performing de-aliasing processing on the first blood flow velocity based on the first de-aliasing coefficient to obtain the first projection component of the blood flow velocity vector at the position of the blood flow to be measured on the first emission angle; when the value result of N is used as the first de-aliasing coefficient, performing de-aliasing processing on the second blood flow velocity based on the first de-aliasing coefficient to obtain the first projection component of the blood flow velocity vector at the position of the blood flow to be measured on the first emission angle; Determining a second de-aliasing coefficient that satisfies a second preset condition according to the third blood flow velocity, the fourth blood flow velocity, the third maximum measurable velocity, and the fourth maximum measurable velocity includes: Taking the difference between the third blood flow velocity and the fourth blood flow velocity as a fourth difference; Taking twice the difference between N times the third maximum measurable velocity and M times the fourth maximum measurable velocity as a fifth difference, where both N and M are integers; Taking the difference between the fourth difference and the fifth difference as a sixth difference; Calculating the value results of M and N that minimize the absolute value of the sixth difference, and taking M and / or N in the value results as the second de-aliasing coefficient; Wherein, when the value of M is used as the second aliasing removal coefficient, the third blood flow velocity is processed for aliasing removal based on the second aliasing removal coefficient, so as to obtain a second projection component of the blood flow velocity vector at the position of the blood flow to be measured on the second emission angle; when the value of N is used as the second aliasing removal coefficient, the fourth blood flow velocity is processed for aliasing removal based on the second aliasing removal coefficient, so as to obtain a second projection component of the blood flow velocity vector at the position of the blood flow to be measured on the second emission angle.

16. The method according to claim 15, wherein when there are at least two sets of value results of M and N such that the absolute value of the third difference obtains a minimum value, the M and / or N with the minimum absolute value in the value results is used as the first aliasing removal coefficient; when there are at least two sets of value results of M and N such that the absolute value of the sixth difference obtains a minimum value, the M and / or N with the minimum absolute value in the value results is used as the second aliasing removal coefficient.

17. The method according to claim 15, characterized in that, The method further includes: In the echo signal sequence composed of the first echo signal, the second echo signal, the third echo signal, the fourth echo signal, the fifth echo signal, the sixth echo signal, the seventh echo signal, and the eighth echo signal, the echo signals with the same emission angle and the same emission time interval between each other are used as a group of signals, at least two groups of echo signals are obtained, and wall filtering is respectively performed on each group of echo signals. The echo signals obtained after wall filtering are used to calculate the first blood flow velocity, the second blood flow velocity, the third blood flow velocity, and the fourth blood flow velocity.

18. The method according to claim 14, wherein The emission order of the first ultrasonic wave, the second ultrasonic wave, the third ultrasonic wave, the fourth ultrasonic wave, the fifth ultrasonic wave, the sixth ultrasonic wave, the seventh ultrasonic wave, and the eighth ultrasonic wave is: the first ultrasonic wave, the fifth ultrasonic wave, the second ultrasonic wave, the sixth ultrasonic wave, the third ultrasonic wave, the seventh ultrasonic wave, the fourth ultrasonic wave, the eighth ultrasonic wave; or the first ultrasonic wave, the second ultrasonic wave, the fifth ultrasonic wave, the sixth ultrasonic wave, the third ultrasonic wave, the fourth ultrasonic wave, the seventh ultrasonic wave, the eighth ultrasonic wave; or the first ultrasonic wave, the second ultrasonic wave, the third ultrasonic wave, the fifth ultrasonic wave, the sixth ultrasonic wave, the seventh ultrasonic wave, the fourth ultrasonic wave, the eighth ultrasonic wave; or the first ultrasonic wave, the second ultrasonic wave, the third ultrasonic wave, the fourth ultrasonic wave, the fifth ultrasonic wave, the sixth ultrasonic wave, the seventh ultrasonic wave, the eighth ultrasonic wave.

19. The method according to claim 14, characterized in that, The first pulse repetition frequency and the second pulse repetition frequency are relatively prime to each other, and the third pulse repetition frequency and the fourth pulse repetition frequency are relatively prime to each other.

20. The method according to claim 14, wherein The reciprocal of the maximum value among the first pulse repetition frequency, the second pulse repetition frequency, the third pulse repetition frequency, and the fourth pulse repetition frequency is greater than twice the ratio of the blood flow imaging depth to the sound velocity of the ultrasonic wave propagating in the blood flow to be measured.

21. The method according to claim 14, wherein The first pulse repetition frequency is the same as the third pulse repetition frequency, and the second pulse repetition frequency is the same as the fourth pulse repetition frequency.

22. The method according to claim 14, wherein Receiving the echo of the ultrasonic wave includes: receiving the echo of the ultrasonic wave at one or more receiving angles.

23. The method according to any one of claims 14-22, characterized in that, The first ultrasonic wave, the second ultrasonic wave, the third ultrasonic wave, the fourth ultrasonic wave, the fifth ultrasonic wave, the sixth ultrasonic wave, the seventh ultrasonic wave, and the eighth ultrasonic wave are all non-focused ultrasonic waves, and the method further includes: Emitting a focused ultrasonic wave to the position of the blood flow to be measured, and receiving the echo of the focused ultrasonic wave to obtain a focused echo signal; Generating a grayscale image of the position of the blood flow to be measured based on the focused echo signal; Generating a blood flow velocity vector map based on the blood flow velocity vector of the position of the blood flow to be measured; Displaying the grayscale image and superimposing and displaying the blood flow velocity vector map on the grayscale image.

24. The method according to claim 23, wherein The focused ultrasonic wave is emitted between any two adjacent ones of the first ultrasonic wave, the second ultrasonic wave, the third ultrasonic wave, the fourth ultrasonic wave, the fifth ultrasonic wave, the sixth ultrasonic wave, the seventh ultrasonic wave, and the eighth ultrasonic wave.

25. The method according to claim 23, wherein The reciprocal of the minimum value among the first pulse repetition frequency, the second pulse repetition frequency, the third pulse repetition frequency, and the fourth pulse repetition frequency is the maximum emission time interval, and the focused ultrasonic wave is emitted between the two ultrasonic waves corresponding to the maximum emission time interval.

26. The method according to claim 14, wherein The method further includes: Emitting a ninth ultrasonic wave, a tenth ultrasonic wave, an eleventh ultrasonic wave, and a twelfth ultrasonic wave to the position of the blood flow to be measured at a third emission angle different from the first emission angle and the second emission angle, and receiving the echo of the ultrasonic wave to obtain a ninth echo signal, a tenth echo signal, an eleventh echo signal, and a twelfth echo signal; wherein, there is a fifth pulse repetition frequency between the ninth ultrasonic wave and the tenth ultrasonic wave, and there is a sixth pulse repetition frequency between the eleventh ultrasonic wave and the twelfth ultrasonic wave, and the fifth pulse repetition frequency and the sixth pulse repetition frequency are not in an integer multiple relationship; Obtaining a third projection component of the blood flow velocity vector of the position of the blood flow to be measured on the third emission angle according to the ninth echo signal, the tenth echo signal, the eleventh echo signal, the twelfth echo signal, the fifth pulse repetition frequency, and the sixth pulse repetition frequency; The synthesizing the first projection component and the second projection component to obtain the blood flow velocity vector of the position of the blood flow to be measured includes: Synthesizing the first projection component, the second projection component, and the third projection component to obtain a three-dimensional blood flow velocity vector of the position of the blood flow to be measured.

27. An ultrasonic blood flow imaging method, characterized in that, The method includes: Emit a first ultrasonic wave, a second ultrasonic wave, and a third ultrasonic wave at a first emission angle toward a blood flow position to be measured of a target object, and receive the echoes of the ultrasonic waves to obtain a first echo signal, a second echo signal, and a third echo signal; wherein, a first pulse repetition frequency exists between the first ultrasonic wave and the second ultrasonic wave, a second pulse repetition frequency exists between the second ultrasonic wave and the third ultrasonic wave, and the first pulse repetition frequency and the second pulse repetition frequency are not in an integer multiple relationship; Emit a fourth ultrasonic wave, a fifth ultrasonic wave, a sixth ultrasonic wave, and a seventh ultrasonic wave at a second emission angle different from the first emission angle toward the blood flow position to be measured, and receive the echoes of the ultrasonic waves to obtain a fourth echo signal, a fifth echo signal, a sixth echo signal, and a seventh echo signal; wherein, a third pulse repetition frequency exists between the fourth ultrasonic wave and the fifth ultrasonic wave, a fourth pulse repetition frequency exists between the sixth ultrasonic wave and the seventh ultrasonic wave, and the third pulse repetition frequency and the fourth pulse repetition frequency are not in an integer multiple relationship; Obtain a first projection component of the blood flow velocity vector at the blood flow position to be measured on the first emission angle according to the first echo signal, the second echo signal, the third echo signal, the first pulse repetition frequency, and the second pulse repetition frequency; Obtain a second projection component of the blood flow velocity vector at the blood flow position to be measured on the second emission angle according to the fourth echo signal, the fifth echo signal, the sixth echo signal, the seventh echo signal, the third pulse repetition frequency, and the fourth pulse repetition frequency; Synthesize the first projection component and the second projection component to obtain the blood flow velocity vector at the blood flow position to be measured; Wherein, the obtaining a first projection component of the blood flow velocity vector at the blood flow position to be measured on the first emission angle according to the first echo signal, the second echo signal, the third echo signal, the first pulse repetition frequency, and the second pulse repetition frequency includes: Obtain a first blood flow velocity according to the first echo signal and the second echo signal, and obtain a second blood flow velocity according to the second echo signal and the third echo signal; Obtain a first maximum measurable velocity corresponding to the first pulse repetition frequency and a second maximum measurable velocity corresponding to the second pulse repetition frequency; Determine a first dealiasing coefficient that satisfies a first preset condition according to the first blood flow velocity, the second blood flow velocity, the first maximum measurable velocity, and the second maximum measurable velocity; Perform dealiasing processing on the first blood flow velocity and / or the second blood flow velocity based on the first dealiasing coefficient to obtain a first projection component of the blood flow velocity vector at the blood flow position to be measured on the first emission angle; The obtaining a second projection component of the blood flow velocity vector at the blood flow position to be measured on the second emission angle according to the fourth echo signal, the fifth echo signal, the sixth echo signal, the seventh echo signal, the third pulse repetition frequency, and the fourth pulse repetition frequency includes: Obtain a third blood flow velocity based on the fourth echo signal and the fifth echo signal, and obtain a fourth blood flow velocity based on the sixth echo signal and the seventh echo signal; Obtain a third maximum measurable velocity corresponding to the third pulse repetition frequency and a fourth maximum measurable velocity corresponding to the fourth pulse repetition frequency; Determine a second aliasing removal coefficient that satisfies a second preset condition based on the third blood flow velocity, the fourth blood flow velocity, the third maximum measurable velocity, and the fourth maximum measurable velocity; Perform aliasing removal processing on the third blood flow velocity and / or the fourth blood flow velocity based on the second aliasing removal coefficient to obtain a second projection component of the blood flow velocity vector at the measured blood flow position on the second emission angle.

28. The method according to claim 27, wherein The determining the first aliasing removal coefficient that satisfies the first preset condition based on the first blood flow velocity, the second blood flow velocity, the first maximum measurable velocity, and the second maximum measurable velocity includes: Taking the difference between the first blood flow velocity and the second blood flow velocity as a first difference; Taking twice the difference between N times the second maximum measurable velocity and M times the first maximum measurable velocity as a second difference, where both N and M are integers; Taking the difference between the first difference and the second difference as a third difference; Calculating the value results of M and N that minimize the absolute value of the third difference, and taking M and / or N in the value results as the first aliasing removal coefficient; Wherein, when the value result of M is used as the first aliasing removal coefficient, perform aliasing removal processing on the first blood flow velocity based on the first aliasing removal coefficient to obtain a first projection component of the blood flow velocity vector at the measured blood flow position on the first emission angle; when the value result of N is used as the first aliasing removal coefficient, perform aliasing removal processing on the second blood flow velocity based on the first aliasing removal coefficient to obtain a first projection component of the blood flow velocity vector at the measured blood flow position on the first emission angle; The determining the second aliasing removal coefficient that satisfies the second preset condition based on the third blood flow velocity, the fourth blood flow velocity, the third maximum measurable velocity, and the fourth maximum measurable velocity includes: Taking the difference between the third blood flow velocity and the fourth blood flow velocity as a fourth difference; Taking twice the difference between N times the third maximum measurable velocity and M times the fourth maximum measurable velocity as a fifth difference, where both N and M are integers; Taking the difference between the fourth difference and the fifth difference as a sixth difference; Calculating the value results of M and N that minimize the absolute value of the sixth difference, and taking M and / or N in the value results as the second aliasing removal coefficient; Wherein, when the value of M is used as the second aliasing removal coefficient, the third blood flow velocity is processed for aliasing removal based on the second aliasing removal coefficient to obtain the second projection component of the blood flow velocity vector at the measured blood flow position on the second emission angle; when the value of N is used as the second aliasing removal coefficient, the fourth blood flow velocity is processed for aliasing removal based on the second aliasing removal coefficient to obtain the second projection component of the blood flow velocity vector at the measured blood flow position on the second emission angle.

29. The method according to claim 28, wherein when there are at least two sets of value results of M and N such that the absolute value of the third difference obtains the minimum value, the M and / or N with the minimum absolute value in the value results is used as the first aliasing removal coefficient; when there are at least two sets of value results of M and N such that the absolute value of the sixth difference obtains the minimum value, the M and / or N with the minimum absolute value in the value results is used as the second aliasing removal coefficient.

30. The method according to claim 27, wherein The method further includes: In the echo signal sequence composed of the first echo signal, the second echo signal, the third echo signal, the fourth echo signal, the fifth echo signal, the sixth echo signal and the seventh echo signal, the echo signals with the same emission angle and the same emission time interval between each other are used as a group of signals to obtain at least two groups of echo signals, and wall filtering is performed on each group of echo signals respectively. The echo signals obtained after wall filtering are used to calculate the first blood flow velocity, the second blood flow velocity, the third blood flow velocity and the fourth blood flow velocity.

31. The method according to claim 27, wherein The method further includes: emitting the eighth ultrasonic wave, the ninth ultrasonic wave and the tenth ultrasonic wave to the measured blood flow position at a third emission angle different from the first emission angle and the second emission angle, and receiving the echoes of the ultrasonic waves to obtain the eighth echo signal, the ninth echo signal and the tenth echo signal; wherein, there is a fifth pulse repetition frequency between the eighth ultrasonic wave and the ninth ultrasonic wave, and there is a sixth pulse repetition frequency between the ninth ultrasonic wave and the tenth ultrasonic wave, and the fifth pulse repetition frequency and the sixth pulse repetition frequency are not in an integer multiple relationship; obtaining the third projection component of the blood flow velocity vector at the measured blood flow position on the third emission angle according to the eighth echo signal, the ninth echo signal, the tenth echo signal, the fifth pulse repetition frequency and the sixth pulse repetition frequency; The synthesizing the first projection component and the second projection component to obtain the blood flow velocity vector at the measured blood flow position includes: synthesizing the first projection component, the second projection component and the third projection component to obtain the three-dimensional blood flow velocity vector at the measured blood flow position.

32. The method according to claim 27, wherein The method further includes: Emit the eighth ultrasonic wave, the ninth ultrasonic wave, the tenth ultrasonic wave, and the eleventh ultrasonic wave to the blood flow position to be measured at a third emission angle different from the first emission angle and the second emission angle, and receive the echoes of the ultrasonic waves to obtain an eighth echo signal, a ninth echo signal, a tenth echo signal, and an eleventh echo signal; wherein, there is a fifth pulse repetition frequency between the eighth ultrasonic wave and the ninth ultrasonic wave, there is a sixth pulse repetition frequency between the tenth ultrasonic wave and the eleventh ultrasonic wave, and the fifth pulse repetition frequency and the sixth pulse repetition frequency are not in an integer multiple relationship; Obtain a third projection component of the blood flow velocity vector at the blood flow position to be measured on the third emission angle according to the eighth echo signal, the ninth echo signal, the tenth echo signal, the eleventh echo signal, the fifth pulse repetition frequency, and the sixth pulse repetition frequency; The synthesizing the first projection component and the second projection component to obtain the blood flow velocity vector at the blood flow position to be measured includes: Synthesize the first projection component, the second projection component, and the third projection component to obtain a three-dimensional blood flow velocity vector at the blood flow position to be measured.

33. An ultrasonic imaging device, characterized in that, The device includes a transmitting circuit, a receiving circuit, an ultrasonic probe, and a processor, wherein: The transmitting circuit is configured to control the ultrasonic probe to emit ultrasonic waves to the blood flow position to be measured of a target object; The receiving circuit is configured to control the ultrasonic probe to receive the echoes of the ultrasonic waves and obtain echo signals from the echoes of the ultrasonic waves; The processor is configured to perform ultrasonic blood flow imaging based on the echo signals; The processor is further configured to execute the ultrasonic blood flow imaging method according to any one of claims 1-32.

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