Ultrasonic blood flow imaging method and ultrasonic imaging device

Abstract

The invention discloses an ultrasonic blood flow imaging method and an ultrasonic imaging device, and the method comprises the steps: transmitting a first ultrasonic wave, a second ultrasonic wave and a third ultrasonic wave to a to-be-measured blood flow position of a target object at a first transmitting angle, so as to obtain a first projection component of a blood flow velocity vector of the to-be-measured blood flow position on the first transmitting angle, 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 in a non-integer multiple relation; the fourth ultrasonic wave, the second ultrasonic wave, the third ultrasonic wave, the fourth ultrasonic wave, the fifth ultrasonic wave and the sixth ultrasonic wave are transmitted to the to-be-measured blood flow position at a second transmitting angle to obtain a second projection component of the blood flow velocity vector of the to-be-measured blood flow position on the second transmitting angle, and 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 in a non-integer multiple relation.

Description

[0001] This application is a divisional application of the invention patent application with the application date of September 9, 2021, application number 202111056959.3, and invention name “Ultrasonic blood flow imaging method and ultrasonic imaging device”. Technical Field

[0002] The present application relates to the field of ultrasonic imaging technology, and more specifically to an ultrasonic blood flow imaging method and an ultrasonic imaging device. Background Art

[0003] 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 results, making the measured values ​​incorrect. Increasing the pulse repetition frequency (PRF) and lowering the center frequency of the transmitted waveform can increase the maximum measurable velocity. However, PRF is limited by the speed of sound and the imaging depth and cannot be increased indefinitely. When using ultrasonic vector blood flow imaging, due to the limitation of the imaging depth, the PRF used to calculate the velocity between the same angles is lower, and aliasing is more likely to occur, resulting in measurement errors. Vector blood flow imaging focuses more on the accuracy of quantitative measurement, so aliasing should be avoided. Summary of the Invention

[0004] The present application is proposed to solve the above-mentioned problems. According to one aspect of the present application, an ultrasonic blood flow imaging method is provided, the method comprising: emitting a first ultrasonic wave, a second ultrasonic wave and a third ultrasonic wave to a blood flow position to be measured on a target object at a first emission angle, 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, 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 non-integer multiples; emitting a fourth ultrasonic wave, a fifth ultrasonic wave and a sixth ultrasonic wave to the blood flow position to be measured at a second emission angle different from the first emission angle, and receiving echoes of the ultrasonic waves to obtain a fourth echo signal, a fifth echo signal and a sixth echo signal; wherein, the fourth ultrasonic wave and the second ultrasonic wave have a first pulse repetition frequency, and the second pulse repetition frequency and the third ultrasonic wave have a second pulse repetition frequency, and the first pulse repetition frequency and the second pulse repetition frequency are non-integer multiples. There is a third pulse repetition frequency between 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 non-integer multiples; 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 of the blood flow position to be measured at the first emission angle is obtained; 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 of the blood flow position to be measured at the second emission angle is obtained; 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.

[0005] According to another aspect of the present application, a method for ultrasonic blood flow imaging is provided, the method comprising: emitting a first ultrasonic wave, a second ultrasonic wave, a third ultrasonic wave and a fourth ultrasonic wave to a blood flow position to be measured on a target object at a first emission angle, and receiving 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, the first ultrasonic wave and the second ultrasonic wave have a first pulse repetition frequency, the third ultrasonic wave and the fourth ultrasonic wave have a second pulse repetition frequency, and the first pulse repetition frequency and the second pulse repetition frequency are non-integer multiples; emitting a fifth ultrasonic wave, a sixth ultrasonic wave, a seventh ultrasonic wave and an eighth ultrasonic wave to the blood flow position to be measured at a second emission angle different from the first emission angle, and receiving 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, the fifth ultrasonic wave There is a third pulse repetition frequency between the sound 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 non-integer multiples; 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 of the blood flow position to be measured at the first emission angle is obtained; 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 of the blood flow position to be measured at the second emission angle is obtained; 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.

[0006] According to another aspect of the present application, a method for ultrasonic blood flow imaging is provided, 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 on a target object at a first transmission angle, and receiving echoes of the ultrasonic waves to obtain a first echo signal, a second echo signal, and a third echo signal; wherein, the first ultrasonic wave and the second ultrasonic wave have a first pulse repetition frequency, the second ultrasonic wave and the third ultrasonic wave have a second pulse repetition frequency, and the first pulse repetition frequency and the second pulse repetition frequency are non-integer multiples; transmitting a fourth ultrasonic wave, a fifth ultrasonic wave, a sixth ultrasonic wave, and a seventh ultrasonic wave to the blood flow position to be measured at a second transmission angle different from the first transmission angle, 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, the fourth ultrasonic wave There is a third pulse repetition frequency between the sixth 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 non-integer multiples; 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 of the blood flow position to be measured at the first emission angle is obtained; 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, a second projection component of the blood flow velocity vector of the blood flow position to be measured at the second emission angle is obtained; 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.

[0007] According to another aspect of the present application, an ultrasonic imaging device is provided, which includes a transmitting circuit, a receiving circuit, an ultrasonic probe and a processor, wherein: the transmitting circuit is used to control the ultrasonic probe to transmit ultrasonic waves to the blood flow position to be measured of the target object; the receiving circuit is used to control the ultrasonic probe to receive the echo of the ultrasonic wave and obtain an echo signal from the echo of the ultrasonic wave; the processor is used to perform ultrasonic blood flow imaging based on the echo signal; and the processor is also used to execute the above-mentioned ultrasonic blood flow imaging method.

[0008] According to the ultrasonic blood flow imaging method and ultrasonic imaging device of the embodiment of the present application, ultrasonic waves are transmitted to the blood flow position to be measured of the target object at at least two transmission angles. Each transmission angle adopts a non-uniform PRF to transmit ultrasonic waves, 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The above and other purposes, features, and advantages of the present application will become more apparent through a more detailed description of the embodiments of the present application in conjunction with the accompanying drawings. The accompanying drawings are intended 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 of the present application. In the drawings, the same reference numerals generally represent the same components or steps.

[0010] Figure 1 A schematic flowchart of an ultrasonic blood flow imaging method according to an embodiment of the present application is shown.

[0011] Figure 2 An exemplary schematic diagram showing the emission of ultrasonic waves in the ultrasonic blood flow imaging method according to an embodiment of the present application is shown.

[0012] Figure 3 An exemplary schematic diagram illustrating transmitting focused ultrasound waves between unfocused ultrasound waves in an ultrasound blood flow imaging method according to an embodiment of the present application is shown.

[0013] Figure 4 An exemplary diagram illustrating grouping transmitted ultrasonic waves to perform wall filtering on respective echo signals in an ultrasonic blood flow imaging method according to an embodiment of the present application is shown.

[0014] Figure 5 Another exemplary diagram shows grouping transmitted ultrasonic waves to perform wall filtering on respective echo signals in an ultrasonic blood flow imaging method according to an embodiment of the present application.

[0015] Figure 6 An exemplary schematic diagram showing multiple consecutive transmissions of the same PRF at the same angle in the ultrasonic blood flow imaging method according to an embodiment of the present application is shown.

[0016] Figure 7 A schematic flowchart showing an ultrasonic blood flow imaging method according to another embodiment of the present application is shown.

[0017] Figure 8 A schematic structural block diagram of an ultrasonic imaging device according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the present application more apparent, example embodiments according to the present application will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application, and it should be understood that the present application is not limited to the example embodiments described herein. Based on the embodiments of the present application described in this application, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of this application.

[0019] Figure 1 FIG. 1 shows a schematic flow chart of an ultrasonic blood flow imaging method 100 according to an embodiment of the present application. Figure 1 As shown, the ultrasound blood flow imaging method 100 may include the following steps:

[0020] In step S110, a first ultrasonic wave, a second ultrasonic wave, and a third ultrasonic wave are transmitted to a blood flow position to be measured of a target object at a first transmission angle, and 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 is provided between the first ultrasonic wave and the second ultrasonic wave, a second pulse repetition frequency is provided between the second ultrasonic wave and the third ultrasonic wave, and the first pulse repetition frequency and the second pulse repetition frequency are non-integer multiples.

[0021] In step S120, a fourth ultrasonic wave, a fifth ultrasonic wave, and a sixth ultrasonic wave are transmitted toward the blood flow location to be measured at a second transmission angle different from the first transmission angle, and 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 is provided between the fourth ultrasonic wave and the fifth ultrasonic wave, a fourth pulse repetition frequency is provided between the fifth ultrasonic wave and the sixth ultrasonic wave, and the third pulse repetition frequency and the fourth pulse repetition frequency are non-integer multiples of each other;

[0022] In step S130, a first projection component of a blood flow velocity vector at a blood flow position to be measured at a first transmission angle is obtained 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;

[0023] In step S140, a second projection component of the blood flow velocity vector at the blood flow position to be measured at a second transmission angle is obtained 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;

[0024] In step S150, the first projection component and the second projection component are synthesized to obtain a blood flow velocity vector of the blood flow position to be measured.

[0025] In an embodiment of the present application, ultrasound waves are transmitted at at least two transmission angles toward a blood flow location to be measured on a target subject. The ultrasound waves transmitted at each transmission angle have at least two pulse repetition frequencies (PRFs), and these at least two PRFs are non-integer multiples of each other. This means that each transmission angle transmits ultrasound waves with a non-uniform PRF, which can achieve a larger actual PRF, thereby increasing the maximum measurable velocity and, in turn, improving the measurement accuracy of the blood flow velocity vector at the blood flow location to be measured. The following describes in detail why the ultrasound blood flow imaging method 100 can increase the maximum measurable velocity.

[0026] First, the blood flow velocity calculation formula based on the Doppler principle is as follows:

[0027]

[0028] in:

[0029]

[0030] In the above formula (1), v z is the blood flow velocity component measured along the direction of ultrasound propagation, f0 is the center frequency of the probe emission signal, and f PRF is the pulse repetition frequency (PRF) (i.e., the reciprocal of the time interval between two adjacent transmissions); N in the expression R(1) 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.

[0031] For the convenience of expression, The range of arctan(A) is (-ππ], so the maximum measurable speed (in absolute value) of formula (1) can be expressed as:

[0032]

[0033] The speed range of formula (1) can be expressed as [-v max v max ). When the actual speed is greater than v max or less than -v max When the measurement result is aliased (Note: the actual velocity here refers to the actual value of the velocity component along the ultrasonic emission direction, and the measured value is also this value). The correct velocity component measurement value should be:

[0034]

[0035] When no aliasing occurs, M = 0, and formula (2) is equivalent to formula (1). When aliasing occurs, M is a non-zero integer, including positive and negative integers, such as -3, -2, -1, 1, 2, 3, etc. Since M is unknown, more information is needed to obtain v z-corr .

[0036] Based on this, in the embodiment of the present application, the ultrasound blood flow imaging method 100 transmits ultrasound waves to the blood flow position to be measured in the target object at two transmission angles, and the ultrasound waves transmitted at each transmission angle have two different PRFs. We take the two PRFs of the first transmission angle as an example to describe, and denote the first pulse repetition frequency as f PRF1, the second pulse repetition frequency is expressed as f PRF2 Based on this, formula (2) can be expanded into a set of equations containing two PRFs:

[0037]

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

[0039] First, aliasing will occur first when the PRF is small. Therefore, when f PRF1 >f PRF2 When |M|≤|N|; otherwise, when f PRF1 <f PRF2 When , |M|≥|N|.

[0040] To simplify further, assume:

[0041]

[0042] Then formulas (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 formula (7), B1, B2, v max1 , v max2 It is known that different M and N can be tried to make formula (7) as valid as possible. This operation can be further formulated as follows:

[0048] argmin M,N |(B1-B2)-2(Nv max2 -Mv max1 )|(8)

[0049]

[0050] In formula (8), Represents a set of integers. Multiple sets of solutions for M and N can be found through exhaustive enumeration. Then, the M or N with the smallest absolute value is substituted into formula (3) or (4) to calculate the actual speed after de-aliasing.

[0051] Since there are two unknowns in formula (7), namely M and N, there are infinite sets of solutions to make this equation true. Therefore, during the calculation, each set of M and N corresponds to a measurement result, so there are infinitely many measured values, which means that these measured values ​​may be the actual blood flow velocity. Considering that the blood flow velocity cannot be infinite, it is generally believed that the velocity measurement corresponding to the M or N with the smallest absolute value is the actual velocity measurement. Of course, this is an assumption. When the actual measurement value is greater than the velocity measurement corresponding to the M or N with the smallest absolute value, it is also equivalent to aliasing. However, the maximum measurable velocity of this method is already much higher than that of traditional methods.

[0052] Therefore, according to the ultrasonic blood flow imaging method 100 of the embodiment of the present application, ultrasonic waves are transmitted to the blood flow position to be measured of the target object at at least two transmission angles, and each transmission angle adopts a non-uniform PRF to transmit ultrasonic waves, 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.

[0053] 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 may also be after step S130.

[0054] In an embodiment of the present application, obtaining a first projection component of a blood flow velocity vector at a blood flow position to be measured at a 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 in step S130 may include: 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 anti-aliasing coefficient that meets 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 a first projection component of the blood flow velocity vector at the blood flow position to be measured at the first transmission angle.

[0055] The process of calculating the first projection component of the blood flow velocity vector at the blood flow position to be measured in this embodiment can be understood in conjunction with the formulas in the previous text. Among them, the first blood flow velocity can be understood as B1 in the previous formula (8), 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 The second maximum measurable speed can be understood as v in the previous formula (8) max2 ; The first anti-aliasing coefficient can be understood as M and / or N in the previous formula (8); the first preset condition can be understood as making formula (8) valid.

[0056] Based on this, determining the first anti-aliasing 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 (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(Nv max2 -Mv max1 )), where N and M are both integers; the difference between the first difference and the second difference is taken as the third difference (ie (B1-B2)-2(Nv max2 -Mv max1 )); Calculate the value of M and N that minimizes the absolute value of the third difference (ie, formula (8)), and use M and / or N in the value result as the first anti-aliasing coefficient.

[0057] Since the value of M corresponds to the first blood flow velocity B1, when the value of M is used as the first anti-aliasing coefficient, the first blood flow velocity is subjected to anti-aliasing processing 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, that is, the first projection component of the blood flow velocity vector at the blood flow position to be measured at the first emission angle is calculated by the above formula (5). Since the value of N corresponds to the first blood flow velocity B2, when the value of N is used as the first anti-aliasing coefficient, the second blood flow velocity is subjected to anti-aliasing processing 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, that is, the first projection component of the blood flow velocity vector at the blood flow position to be measured at the first emission angle is calculated by the above formula (6). Alternatively, the projection component obtained by performing anti-aliasing processing on the first blood flow velocity using the above-mentioned M as the first anti-aliasing coefficient and the projection component obtained by performing anti-aliasing processing on the first blood flow velocity using the above-mentioned N as the first anti-aliasing coefficient may be averaged, and the averaged result may be used as the first projection component of the blood flow velocity vector at the final blood flow position to be measured at the first emission angle.

[0058] In an embodiment of the present application, when there are at least two sets of M and N value results, so that the absolute value of the aforementioned third difference reaches the minimum value, 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 later in conjunction with an example below.

[0059] In an embodiment of the present application, obtaining a second projection component of the blood flow velocity vector at the blood flow position to be measured at the second transmission angle based on 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 a third blood flow velocity based on the fourth echo signal and the fifth echo signal, and obtaining a fourth blood flow velocity based on the fifth echo signal and the sixth 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 anti-aliasing coefficient that meets 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; 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 a second projection component of the blood flow velocity vector at the blood flow position to be measured at the second transmission angle.

[0060] Here, the method of calculating the second projection component of the blood flow velocity vector at the blood flow position to be measured is similar to the method of calculating the first projection component described above, except that the data used in the calculation are different. For ease of understanding, let the third pulse repetition frequency be f PRF3 , the fourth pulse repetition frequency is f PRF4 , then the previous formulas (5) to (8) can be transformed into:

[0061] v z-corr =B3+2Mv max3 (9)

[0062] v z-corr =B4+2Nv max4 (10)

[0063] B3-B4=2(Nv max4 -Mv max3 )(11)

[0064] argmin M,N |(B3-B4)-2(Nv max4 -Mv max3 )|(12)

[0065] Therefore, the third blood flow velocity can be understood as B3 in the previous formula (12), 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 in the previous formula (12). 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. M and N in formulas (5) to (8) have the same meaning as M and N in formulas (9) to (12), but may have different values ​​based on different data sources. The use of the same letter here is only for illustrative purposes and does not necessarily mean that the two are the same.

[0066] 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 values ​​of M and N that minimize the absolute value of the sixth difference (ie, formula (12)), and use M and / or N in the value result as the second anti-aliasing coefficient.

[0067] 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). Alternatively, the projection component obtained by performing anti-aliasing processing on the third blood flow velocity using the above-mentioned M as the second anti-aliasing coefficient and the projection component obtained by performing anti-aliasing processing on the fourth blood flow velocity using the above-mentioned N as the second anti-aliasing coefficient may be averaged, and the averaged result may be 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.

[0068] In an embodiment of the present application, when there are at least two sets of M and N value results such that the absolute value of the sixth difference reaches a minimum, M and / or N with the smallest absolute value in the value results is used as the second anti-aliasing coefficient.

[0069] Now, some instances of the method 100 according to the embodiment of the present application are described by taking the first emission angle as an example. It should be understood that the second emission angle is also a similar situation.

[0070] In one example, assuming that the first pulse repetition frequency is 3k (i.e., 3000 Hz) and 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 transmission signal is 5 MHz, the maximum measurable speeds (in absolute values) corresponding to the first and second pulse repetition frequencies are:

[0071]

[0072]

[0073] The following describes how to use formula (8) to remove aliasing and obtain the actual speed when the measured actual speed exceeds these two values. For example, when the current actual speed is: v = 0.5m / s, then due to aliasing, the obtained B1 and B2 are:

[0074] B1=0.5-2×0.231=0.038m / s

[0075] B2=0.5-2×0.308=-0.116m / s

[0076] B1 and B2, v max1 and v max2 Substitute all into formula (8):

[0077]

[0078] Let |(0.038+0.116)-2(0.308N-0.231M)| be X. Table 1 shows the corresponding X for different M and N values:

[0079] Table 1

[0080]

[0081]

[0082] From the values ​​in Table 1, we can see that the minimum X is obtained when both M and N are 1, as well as when M = 5 and N = 4. Taking M with a relatively small absolute value and substituting M = 1 into formula (3), we can obtain the final value:

[0083]

[0084] It is not difficult to see that the velocity value measured by this method is the same as the actual velocity value, which proves that the method of the present application can accurately measure the projection component of the blood flow velocity at a certain emission angle, and thus can accurately measure the blood flow velocity vector.

[0085] In another example, assuming that the first pulse repetition frequency is 2k (i.e., 2000 Hz) and the second pulse repetition frequency is 9k (i.e., 9000 Hz), when the sound speed c is 1540 m / s and the center frequency of the probe transmission signal is 4 MHz, the maximum measurable speeds (in absolute values) corresponding to the first pulse repetition frequency and the second pulse repetition frequency are respectively:

[0086]

[0087] The following describes how to use formula (8) to remove aliasing and obtain the actual speed when the actual speed exceeds these two values. For example, when the current actual speed is: v = -1m / s, then due to aliasing, the obtained B1 and B2 are:

[0088] B1=-1+3×2×0.1925=0.155m / s

[0089] B2=-1+2×0.86625=0.7325m / s

[0090] B1 and B2, v max1 and v max2 Substitute all into formula (8):

[0091]

[0092] Let |(0.155-0.7324)-(0.8662N-0.1925M)| be X. Table 2 shows the corresponding X for different M and N values.

[0093] Table 2

[0094]

[0095]

[0096] From the values ​​in Table 2, we can see that when M = 6, N = 1, M = -3, N = -1, and M = -12, N = -3, the minimum X is obtained. Taking M with a relatively small absolute value and substituting M = -3 into formula (3), we can get the final value:

[0097]

[0098] In this example, it can also be seen that the velocity value measured by this method is the same as the actual velocity value, which proves that the method of the present application can accurately measure the projection component of the blood flow velocity at a certain emission angle, and thus can accurately measure the blood flow velocity vector.

[0099] In another example, assuming that the first pulse repetition frequency is 3.5k (i.e., 3500 Hz) and the second pulse repetition frequency is 2k (i.e., 2000 Hz), when the sound speed c is 1540 m / s and the center frequency of the probe transmission signal is 5 MHz, the maximum measurable speeds (in absolute values) corresponding to the first pulse repetition frequency and the second pulse repetition frequency are respectively:

[0100]

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

[0102] B1=1.5-3×2×0.2695=-0.117m / s

[0103] B2=1.5-5×2×0.154=-0.04m / s

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

[0105]

[0106] Let |(-0.117+0.04)-2(0.154N-0.2695M)| be X. Table 3 shows the corresponding X for different M and N values.

[0107] Table 3

[0108]

[0109]

[0110] From the values ​​in Table 3, we can see that when M = 3, N = 5, M = 7, N = 12, M = -1, N = -2, and M = -5, N = -9, the minimum X is obtained. Taking M with a relatively small absolute value and substituting M = -1 into formula (3), we can get the final value:

[0111]

[0112] In this example, it can be seen that since the actual velocity is too large, the correct blood flow velocity value cannot be obtained using this method.

[0113] Only by substituting M=3 into formula (3) can we get the correct speed value, that is:

[0114]

[0115] However, when the actual velocity is unknown, it is impossible to know which value of M to substitute to obtain the actual velocity value. This is a limitation of the non-uniform PRF emission blood flow velocity calculation method of this application. However, compared with traditional methods, the maximum measurable velocity has been greatly improved.

[0116] Although the first transmission angle and the second transmission angle are described in the above example, they are only the simplest examples. The present application aims to obtain the velocity component corresponding to each angle (i.e., the projection component mentioned above) by multi-angle transmission (at least two transmission angles), and then perform vector reconstruction based on these velocity components to obtain the blood flow velocity vector. In addition, although the above example describes that the first transmission angle transmits the first to third ultrasonic waves and the second transmission angle transmits the fourth to sixth ultrasonic waves, it is only the simplest example. The present application does not limit the number of ultrasonic waves transmitted at each transmission angle, as long as at least three are satisfied for each transmission angle. In addition, it is also possible to adopt a multi-angle transmission combined with a multi-angle reception method (i.e., receiving ultrasonic echoes at one or more reception angles) to obtain velocity components at multiple different angles, and then perform vector reconstruction based on these velocity components to obtain the blood flow velocity vector, and image the blood flow velocity vector to achieve vector blood flow imaging.

[0117] In an embodiment of the present application, the first emission angle and the second emission angle can be transmitted alternately. In this embodiment, the transmission 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 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. Alternating the two emission angles shortens the time intervals between different angles and makes the synthesized velocity vector more accurate. In other embodiments, the same emission angle can also be transmitted continuously. For example, the transmission 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 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 aforementioned first ultrasonic wave, second ultrasonic wave, third ultrasonic wave, fourth ultrasonic wave, fifth ultrasonic wave, and sixth ultrasonic wave may 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, and 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 second ultrasonic wave, the fifth ultrasonic wave, the sixth ultrasonic wave, and the third ultrasonic wave. The following is combined with Figure 2 To describe by way of example.

[0118] Figure 2 FIG. 1 shows an exemplary schematic diagram of transmitting ultrasound waves in the ultrasound blood flow imaging method according to an embodiment of the present application. Figure 2 As shown, in Figure 2 In the example, two transmission angles are used as examples. The arrow pointing to the left indicates the first transmission angle, and the arrow pointing to the right indicates the second transmission angle. The two PRFs corresponding to the first transmission angle are 6k and 5k, respectively, and the two PRFs corresponding to the second transmission angle are also 6k and 5k, respectively. In this example, when c is 1540m / s and the center frequency of the probe transmission signal is 3MHz, the maximum measurable velocity using the traditional method is (absolute value, when PRF = 6k):

[0119]

[0120] The maximum measurable speed corresponding to the method of this application is:

[0121]

[0122] It is obvious that the method of the present application can improve the maximum measurable speed, wherein the pulse repetition frequency used in obtaining the maximum measurable speed according to the method of the present application is the least common multiple of the two PRFs (i.e., 6k and 5k). For this reason, the first pulse repetition frequency and the second pulse repetition frequency described above are in a non-integer multiple relationship, and the third pulse repetition frequency and the fourth pulse repetition frequency are in a non-integer multiple relationship, otherwise the maximum measurable speed cannot be improved. In addition, it can also be seen that when the first pulse repetition frequency and the second pulse repetition frequency are mutually prime, the maximum measurable speed at the first emission angle can be maximized. Similarly, when the third pulse repetition frequency and the fourth pulse repetition frequency are mutually prime, the maximum measurable speed at the second emission angle can be maximized.

[0123] 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 transmissions. 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 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 means that the minimum transmission 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 emitted ultrasonic waves can be received.

[0124] 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.

[0125] For high-frame-rate vector blood flow imaging, the scanning process is typically unfocused, such as plane waves or diverging waves. This allows for a complete image after a single scan, using beamforming signal processing. However, blood flow imaging also requires maintaining the image quality of traditional grayscale images. To achieve sufficient spatial resolution for grayscale images, focused waves are typically used. This requires alternating scanning with focused and unfocused waves to achieve both high-frame-rate blood flow imaging and high-spatial-resolution grayscale B-images.

[0126] Based on this, in an embodiment of the present application, the aforementioned first ultrasonic wave, second ultrasonic wave, third ultrasonic wave, fourth ultrasonic wave, fifth ultrasonic wave and sixth ultrasonic wave may all be unfocused ultrasonic waves, and method 100 may further include (not shown): transmitting focused ultrasonic waves to the blood flow position to be measured, receiving echoes of the focused ultrasonic waves to obtain focused echo signals; generating a grayscale image of the blood flow position to be measured based on the focused echo signals; generating a blood flow velocity vector map based on the blood flow velocity vector of the blood flow position to be measured; displaying the grayscale image and superimposing the blood flow velocity vector map on the grayscale image.

[0127] The focused ultrasound wave may be transmitted between any two adjacent ultrasound waves among the first ultrasound wave, the second ultrasound wave, the third ultrasound wave, the fourth ultrasound wave, the fifth ultrasound wave, and the sixth ultrasound wave. For example, 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 transmission time interval, and the focused ultrasound wave may be transmitted between the two ultrasound waves corresponding to the maximum transmission time interval.

[0128] The following combination Figure 3 The alternate scanning of focused waves and non-focused waves is exemplified. Figure 3 As shown, the unfocused wave is used for blood flow imaging (arrowed diagonal line), with two different emission angles, each corresponding to two different emission PRFs, 7k and 3k. The focused wave is used for grayscale B-image imaging (vertical line without arrow). In this example, when the sound speed c is 1540m / s and the center frequency of the probe emission signal is 3MHz, the maximum measurable velocity of the traditional method is (absolute value, when PRF = 7k):

[0129]

[0130] The maximum measurable speed corresponding to the method of this application is:

[0131]

[0132] At the same time, the scanning depth is similar to that of conventional vector flow imaging (PRF = 7k) and is not affected because the minimum time interval between two adjacent transmissions remains unchanged and is the reciprocal of 14k.

[0133] In an embodiment of the present application, method 100 may further include: in an echo signal sequence consisting 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, taking echo signals having the same transmission angle and the same transmission time interval between each other as a group of signals to obtain at least two groups of echo signals, and performing wall filtering on each group of echo signals respectively, and using the echo signals obtained after the wall filtering to calculate the first blood flow velocity, the second blood flow velocity, the third blood flow velocity, and the fourth blood flow velocity.

[0134] Wall filtering is to filter the signal, filter out the immobile tissue, and obtain the signal of the moving blood flow. Wall filtering is generally a high-pass filter, and traditional wall filtering includes FIR or IIR filters. However, the input signals of these two filters are generally equidistant signals. This 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 different. Figure 4 and Figure 5 To describe.

[0135] Figure 4 FIG1 shows an example of grouping the transmitted ultrasound waves to perform wall filtering on their respective echo signals in the ultrasound blood flow imaging method according to an embodiment of the present application. Figure 4 As shown in the figure above, two transmission angles use two PRFs, 6k and 5k respectively. The time intervals between two adjacent transmissions or two adjacent transmissions at the same angle at different times are different. Therefore, in order to ensure the normal use of wall filtering, the wall filtering will be performed in the following way: the echo signals with the same transmission angle and the same transmission time interval between each other are regarded as a group of signals to obtain at least two groups of echo signals, and each group of echo signals is subjected to wall filtering separately. Figure 4 As shown in the figure below, different colors are used to distinguish different groups of signals, and signals of the same color (i.e., echo signals with the same emission angle and the same emission time interval between each other) are considered as a group of signals for wall filtering.

[0136] Figure 5 Another example diagram showing the grouping of transmitted ultrasound waves to perform wall filtering on their respective echo signals in the ultrasound blood flow imaging method according to an embodiment of the present application is shown. Figure 5 As shown in the figure above, two PRFs are used for both emission angles, namely 7k and 3k, and a focused wave for grayscale imaging is also emitted during the interval between the non-focused wave emission. Figure 4Similarly, the time intervals between two adjacent transmissions or two adjacent transmissions at the same angle at different times are different. Therefore, in order to ensure the normal use of wall filtering, wall filtering will be performed in the following way: the echo signals with the same transmission angle and the same transmission time interval between each other are taken as a group of signals to obtain at least two groups of echo signals, and each group of echo signals is subjected to wall filtering separately. Figure 5 As shown in the figure below, different colors are used to distinguish different groups of signals, and signals of the same color (i.e., echo signals with the same emission angle and the same emission time interval between each other) are considered as a group of signals for wall filtering.

[0137] Figures 2 to 5 The example of transmitting an ultrasonic wave with the same PRF at the same transmission angle once is used for illustration only, and the number of transmission times is not limited. In actual process, an ultrasonic wave with the same PRF at the same transmission angle may be transmitted multiple times continuously. For example, at least one of the first to sixth ultrasonic waves may be transmitted multiple times continuously, that is, an ultrasonic wave with the same PRF at the same transmission angle may be transmitted once or multiple times continuously. Figure 6 As shown, the same angle and the same PRF are transmitted six times in a row.

[0138] In an embodiment of the present application, a three-dimensional velocity vector can also be calculated. Method 100 can also include: transmitting a seventh ultrasonic wave, an eighth ultrasonic wave, and a ninth ultrasonic wave to the blood flow position to be measured at a third transmission angle different from the first transmission angle and the second transmission angle, and receiving echoes of the ultrasonic waves to obtain a seventh echo signal, an eighth echo signal, and a ninth echo signal; wherein, the seventh ultrasonic wave and the eighth ultrasonic wave have a fifth pulse repetition frequency, the eighth ultrasonic wave and the ninth ultrasonic wave have a sixth pulse repetition frequency, and the fifth pulse repetition frequency and the sixth pulse repetition frequency are non-integer multiples; 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, a third projection component of the blood flow velocity vector of the blood flow position to be measured at the third transmission angle is obtained; and 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, including: synthesizing the first projection component, the second projection component, and the third projection component to obtain the three-dimensional blood flow velocity vector of the blood flow position to be measured. This embodiment adds another emission angle based on method 100. The relevant description can be understood by referring to the aforementioned steps S110 to S150, which will not be repeated here.

[0139] The above exemplifies an ultrasonic blood flow imaging method 100 according to one embodiment of the present application. Based on the above description, the ultrasonic blood flow imaging method 100 according to an embodiment of the present application transmits ultrasonic waves at at least two transmission angles toward a blood flow location to be measured on a target object. Each transmission angle transmits ultrasonic waves with a non-uniform PRF, thereby achieving 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 location to be measured.

[0140] The following combination Figure 7 A schematic flow chart of an ultrasonic blood flow imaging method 700 according to another embodiment of the present application is described. Figure 7 As shown, the ultrasound blood flow imaging method 700 may include the following steps:

[0141] In step S710, a first ultrasonic wave, a second ultrasonic wave, a third ultrasonic wave, and a fourth ultrasonic wave are transmitted to a blood flow position to be measured of a target object at a first transmission angle, and 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, the first ultrasonic wave and the second ultrasonic wave have a first pulse repetition frequency, the third ultrasonic wave and the fourth ultrasonic wave have a second pulse repetition frequency, and the first pulse repetition frequency and the second pulse repetition frequency are non-integer multiples.

[0142] In step S720, a fifth ultrasonic wave, a sixth ultrasonic wave, a seventh ultrasonic wave and an eighth ultrasonic wave are transmitted to the blood flow position to be measured at a second transmission angle different from the first transmission angle, and 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, the fifth ultrasonic wave and the sixth ultrasonic wave have a third pulse repetition frequency, the seventh ultrasonic wave and the eighth ultrasonic wave have a fourth pulse repetition frequency, and the third pulse repetition frequency and the fourth pulse repetition frequency are non-integer multiples.

[0143] In step S730, a first projection component of the blood flow velocity vector of the blood flow position to be measured at the first emission angle is obtained 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.

[0144] In step S740, a second projection component of the blood flow velocity vector of the blood flow position to be measured at the second emission angle is obtained 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.

[0145] In step S750, the first projection component and the second projection component are synthesized to obtain a blood flow velocity vector at the blood flow position to be measured.

[0146] The ultrasonic blood flow imaging method 700 according to an embodiment of the present application is substantially similar to the ultrasonic blood flow imaging method 100 described above, except that: the ultrasonic blood flow imaging method 100 controls all two adjacent 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 there is a second PRF between the second ultrasonic wave and the third ultrasonic wave); in contrast, the ultrasonic blood flow imaging method 700 controls some two adjacent 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, there is 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 multiplex the ultrasonic echo signals when calculating the blood flow velocity (i.e., the first blood flow velocity is obtained based on the first echo signal and the second echo signal, and the second blood flow velocity is obtained based on the second echo signal and the third echo signal, i.e., the second echo signal is multiplexed), while the ultrasonic blood flow imaging method 700 does not need to multiplex the ultrasonic echo signals when calculating the blood flow velocity (i.e., the first blood flow velocity is obtained based on the first echo signal and the second echo signal, and the second blood flow velocity is obtained based on the third echo signal and the fourth echo signal). For the sake of brevity, the similarities between the two will not be described in detail here. The details of the ultrasonic blood flow imaging method 700 can be understood in combination with the above description. Only its main operations are briefly described here.

[0147] In an embodiment of the present application, step S730 of obtaining a first projection component of a blood flow velocity vector of a blood flow position to be measured at a first transmission 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 may include: 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 anti-aliasing coefficient that meets 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 a first projection component of the blood flow velocity vector of the blood flow position to be measured at the first transmission angle.

[0148] Determining a first anti-aliasing coefficient that satisfies a 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 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 N and M are both integers; taking the difference between the first difference and the second difference as the third difference; calculating the values ​​of M and N that minimize the absolute value of the third difference, and taking M and / or N in the calculated values ​​as the first anti-aliasing coefficient; wherein, when the value of M is used as the first anti-aliasing coefficient, performing anti-aliasing processing on the first blood flow velocity based on the first anti-aliasing coefficient to obtain a first projection component of the blood flow velocity vector at the blood flow position to be measured at the first emission angle; and when the value of N is used as the first anti-aliasing coefficient, performing anti-aliasing processing on the second blood flow velocity based on the first anti-aliasing coefficient to obtain a first projection component of the blood flow velocity vector at the blood flow position to be measured at the first emission angle. Alternatively, the projection component obtained by performing anti-aliasing processing on the first blood flow velocity using the above-mentioned M as the first anti-aliasing coefficient and the projection component obtained by performing anti-aliasing processing on the first blood flow velocity using the above-mentioned N as the first anti-aliasing coefficient may be averaged, and the averaged result may be used as the first projection component of the blood flow velocity vector at the final blood flow position to be measured at the first emission angle.

[0149] When there are at least two sets of M and N value results such that the absolute value of the third difference reaches a minimum, M and / or N with the smallest absolute value in the value results is used as the first anti-aliasing coefficient.

[0150] In an embodiment of the present application, obtaining a second projection component of the blood flow velocity vector of the blood flow position to be measured at the second transmission 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 in step S740 may include: 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 anti-aliasing coefficient that meets 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 a second projection component of the blood flow velocity vector of the blood flow position to be measured at the second transmission angle.

[0151] Determining the second anti-aliasing 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 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 N and M are both integers; taking the difference between the fourth difference and the fifth difference as the sixth difference; and calculating M such that the absolute value of the sixth difference is minimized. and N, and use M and / or N in the value result as the second anti-aliasing coefficient; wherein, when the value result of M is used as the second anti-aliasing coefficient, anti-aliasing processing is performed on the third blood flow velocity 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; when the value result of N is used as the second anti-aliasing coefficient, anti-aliasing processing is performed on 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 blood flow position to be measured at the second emission angle. Alternatively, the projection component obtained by anti-aliasing processing the third blood flow velocity using M as the second anti-aliasing coefficient and the projection component obtained by anti-aliasing processing the fourth blood flow velocity using N as the second anti-aliasing coefficient are averaged, and the averaged result is used as the final second projection component of the blood flow velocity vector at the blood flow position to be measured at the second emission angle.

[0152] When there are at least two sets of M and N value results such that the absolute value of the sixth difference value reaches a minimum, M and / or N with the smallest absolute value in the value results is used as the second anti-aliasing coefficient.

[0153] 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 can 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, and 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, and 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, and 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, and the eighth ultrasonic wave. Similarly, with reference to the description of the alternating scanning order in the aforementioned 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, as long as the alternating effect is achieved, and no exhaustive list is given here.

[0154] In an embodiment of the present application, the first pulse repetition frequency and the second pulse repetition frequency are mutually prime, and the third pulse repetition frequency and the fourth pulse repetition frequency are mutually prime.

[0155] 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 ultrasound propagating in the blood flow to be measured.

[0156] 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.

[0157] In an embodiment of the present application, receiving the ultrasonic echo may include: receiving the ultrasonic echo at one or more receiving angles.

[0158] In an embodiment of the present application, the first ultrasound wave, the second ultrasound wave, the third ultrasound wave, the fourth ultrasound wave, the fifth ultrasound wave, the sixth ultrasound wave, the seventh ultrasound wave and the eighth ultrasound wave may all be unfocused ultrasound waves, and method 700 may further include (not shown): transmitting focused ultrasound waves to the blood flow position to be measured, receiving echoes of the focused ultrasound waves to obtain focused echo signals; generating a grayscale image of the blood flow position to be measured based on the focused echo signals; 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 the blood flow velocity vector map on the grayscale image.

[0159] In an embodiment of the present application, the focused ultrasound wave may be emitted between any two adjacent ones of the first ultrasound wave, the second ultrasound wave, the third ultrasound wave, the fourth ultrasound wave, the fifth ultrasound wave, the sixth ultrasound wave, the seventh ultrasound wave, and the eighth ultrasound wave.

[0160] In an embodiment of the present application, the reciprocal of the minimum of the first pulse repetition frequency, the second pulse repetition frequency, the third pulse repetition frequency and the fourth pulse repetition frequency is the maximum transmission time interval, and the focused ultrasound wave can be transmitted between two ultrasound waves corresponding to the maximum transmission time interval.

[0161] In an embodiment of the present application, method 700 may further include (not shown): in an echo signal sequence consisting 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, taking echo signals having the same transmission angle and the same transmission time interval between each other as a group of signals to obtain at least two groups of echo signals, and performing wall filtering on each group of echo signals respectively, and using the echo signals obtained after the wall filtering to calculate the first blood flow velocity, the second blood flow velocity, the third blood flow velocity, and the fourth blood flow velocity.

[0162] In an embodiment of the present application, a three-dimensional velocity vector can also be calculated. Method 700 can also include: transmitting a ninth ultrasonic wave, a tenth ultrasonic wave, an eleventh ultrasonic wave, and a twelfth ultrasonic wave to the blood flow position to be measured at a third transmission angle different from the first transmission angle and the second transmission angle, and receiving echoes of the ultrasonic waves to obtain a ninth echo signal, a tenth echo signal, an eleventh echo signal, and a twelfth echo signal; wherein, the ninth ultrasonic wave and the tenth ultrasonic wave have a fifth pulse repetition frequency, the eleventh ultrasonic wave and the twelfth ultrasonic wave have a sixth pulse repetition frequency, and the fifth pulse repetition frequency and the sixth pulse repetition frequency are non-integer multiples; obtaining a third projection component of the blood flow velocity vector of the blood flow position to be measured at the third transmission 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; synthesizing the first projection component and the second projection component to obtain the blood flow velocity vector of 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 of the blood flow position to be measured. This embodiment adds another emission angle based on method 700. The relevant description can be understood by referring to the aforementioned steps S710 to S750, which will not be repeated here.

[0163] 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 to a blood flow position to be measured on a target object at a first transmitting angle, and receiving echoes of the ultrasonic waves to obtain a first echo signal, a second echo signal, and a third echo signal; wherein the first ultrasonic wave and the second ultrasonic wave have a first pulse repetition frequency, the second ultrasonic wave and the third ultrasonic wave have a second pulse repetition frequency, and the first pulse repetition frequency and the second pulse repetition frequency are non-integer multiples; transmitting a fourth ultrasonic wave, a fifth ultrasonic wave, a sixth ultrasonic wave, and a seventh ultrasonic wave to a blood flow position to be measured at a second transmitting angle different from the first transmitting angle, 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. echo signal and 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 non-integer multiples; 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 of the blood flow position to be measured at the first emission angle is obtained; 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, a second projection component of the blood flow velocity vector of the blood flow position to be measured at the second emission angle is obtained; 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.

[0164] The first transmission angle in the ultrasonic blood flow imaging method of the present embodiment adopts a scheme corresponding to the first transmission angle in the ultrasonic blood flow imaging method 100 described above, and the second transmission angle adopts a scheme corresponding to the second transmission angle in the ultrasonic blood flow imaging method 700 described above. For related explanations, reference can be made to the contents of the aforementioned methods 100 and 700 and will not be repeated here.

[0165] The following combination Figure 8 The ultrasonic imaging device 800 according to an embodiment of the present application is described. Figure 8As shown, the ultrasonic imaging device 800 includes an ultrasonic probe 810, a transmitting circuit 820, a receiving circuit 830, and a processor 830. The transmitting circuit 820 is used to control the ultrasonic probe 810 to transmit ultrasonic waves toward a blood flow location to be measured in a target object; the receiving circuit 830 is used to control the ultrasonic probe 810 to receive ultrasonic echoes and obtain echo signals from the ultrasonic echoes; the processor 840 is used to perform ultrasonic blood flow imaging based on the echo signals; and the processor 840 is further used 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 conjunction with the above description and will not be further described here for the sake of brevity.

[0166] Based on the above description, the ultrasonic blood flow imaging method and device according to the embodiment of the present application transmit ultrasonic waves to the blood flow position to be measured of the target object at at least two transmission angles. Each transmission angle uses a non-uniform PRF to transmit ultrasonic waves, 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.

[0167] Although example embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above example embodiments are merely illustrative and are not intended to limit the scope of the present application. Various changes and modifications may be made therein by those skilled in the art 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 required by the appended claims.

[0168] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0169] In the several embodiments provided in this 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 described is merely a logical function division. In actual implementation, other division methods may be used, such as combining or integrating multiple units or components into another device, or ignoring or not performing some features.

[0170] In the description provided herein, a large number of specific details are described. However, it is understood that the embodiments of the present application can be practiced without these specific details. In some instances, well-known methods, structures, and techniques are not shown in detail so as not to obscure the understanding of this description.

[0171] Similarly, it should be understood that in order to streamline the present application and aid 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 into a single embodiment, figure, or description thereof. However, this approach of the present application should not be interpreted as reflecting the intention that the application claimed for protection requires more features than those explicitly recited in each claim. More precisely, as reflected in the corresponding claims, the inventive point is that the corresponding technical problem can be solved with fewer features than all the features of a single disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into the detailed description, with each claim itself serving as a separate embodiment of the present application.

[0172] It will be understood by those skilled in the art that, except where mutually exclusive, all features disclosed in this specification (including the accompanying claims, abstract, and drawings) and all processes or units of any method or apparatus disclosed herein may be combined in any combination. Unless expressly stated otherwise, each feature disclosed in this specification (including the accompanying claims, abstract, and drawings) may be replaced by an alternative feature providing the same, equivalent, or similar purpose.

[0173] Furthermore, those skilled in the art will appreciate that although some embodiments described herein include certain features included in other embodiments but not other features, combinations of features from different embodiments are intended to be within the scope of this application and to form different embodiments. For example, in the claims, any of the claimed embodiments may be used in any combination.

[0174] The various component embodiments of the present application can be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. It should be understood by those skilled in the art that a microprocessor or 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 embodiment of the present application. The application can also be implemented as a part or all of an ultrasonic imaging device program (e.g., a computer program and a computer program product) for performing the method described herein. Such a program implementing the present application can be stored on a computer-readable medium, or can have the form of one or more signals. Such a signal can be downloaded from an Internet website, or provided on a carrier signal, or provided in any other form.

[0175] It should be noted that the above embodiments illustrate rather than limit the present application, and that those skilled in the art may devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between brackets should 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 may be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In a unit claim listing several ultrasonic imaging devices, several of these ultrasonic imaging devices may be embodied by the same item of hardware. The use of the words first, second, and third, etc. does not indicate any order. These words may be interpreted as names.

[0176] The above description is merely a specific embodiment or illustration of a specific embodiment of the present application, and the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application. The scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A method for ultrasonic blood flow imaging, characterized in that: The method comprises: Transmitting a first ultrasonic wave, a second ultrasonic wave, and a third ultrasonic wave at a first transmission angle toward a blood flow location to be measured in 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 the first ultrasonic wave and the second ultrasonic wave have a first pulse repetition frequency, the second ultrasonic wave and the third ultrasonic wave have a second pulse repetition frequency, and the first pulse repetition frequency and the second pulse repetition frequency are non-integer multiples; transmitting a fourth ultrasonic wave, a fifth ultrasonic wave, and a sixth ultrasonic wave toward the blood flow location to be measured at a second transmitting angle different from the first transmitting angle, and receiving echoes of the ultrasonic waves to obtain a fourth echo signal, a fifth echo signal, and a sixth echo signal; wherein a third pulse repetition frequency is provided between the fourth ultrasonic wave and the fifth ultrasonic wave, a fourth pulse repetition frequency is provided between the fifth ultrasonic wave and the sixth ultrasonic wave, and the third pulse repetition frequency and the fourth pulse repetition frequency are non-integer multiples; 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 first pulse repetition frequency, and the second 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 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; The first projection component and the second projection component are synthesized to obtain a blood flow velocity vector of the blood flow position to be measured.

2. 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, and 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, 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; or 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.

3. The method according to claim 1, characterized in that The first pulse repetition frequency and the second pulse repetition frequency are mutually prime, and the third pulse repetition frequency and the fourth pulse repetition frequency are mutually prime.

4. 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 speed of ultrasound waves propagating in the blood flow to be measured.

5. 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.

6. The method according to any one of claims 1 to 5, 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 unfocused ultrasonic waves, and the method further includes: transmitting focused ultrasound waves to the blood flow position to be measured, and receiving echoes of the focused ultrasound waves to obtain focused echo signals; generating a grayscale image of the blood flow position to be measured based on the focused echo signal; generating a blood flow velocity vector diagram based on the blood flow velocity vector at the blood flow position to be measured; The grayscale image is displayed and the blood flow velocity vector diagram is superimposed on the grayscale image.

7. The method according to claim 6, characterized in that 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, and the sixth ultrasonic wave; or 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 transmission time interval, and the focused ultrasound wave is transmitted between two ultrasound waves corresponding to the maximum transmission time interval.

8. The method according to claim 1, characterized in that The method further comprises: transmitting a seventh ultrasonic wave, an eighth ultrasonic wave, and a ninth ultrasonic wave toward the blood flow location to be measured at a third transmission angle different from the first transmission angle and the second transmission angle, and receiving echoes of the ultrasonic waves to obtain a seventh echo signal, an eighth echo signal, and a ninth echo signal; wherein a fifth pulse repetition frequency is provided between the seventh ultrasonic wave and the eighth ultrasonic wave, a sixth pulse repetition frequency is provided between the eighth ultrasonic wave and the ninth ultrasonic wave, and the fifth pulse repetition frequency and the sixth pulse repetition frequency are non-integer multiples of each other; obtaining a third projection component of the blood flow velocity vector of the blood flow position to be measured at 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 at the blood flow position to be measured includes: The first projection component, the second projection component and the third projection component are synthesized to obtain a three-dimensional blood flow velocity vector of the blood flow position to be measured.

9. An ultrasonic blood flow imaging method, characterized in that: The method comprises: Transmitting a first ultrasonic wave, a second ultrasonic wave, a third ultrasonic wave, and a fourth ultrasonic wave at a first transmission angle toward a blood flow location to be measured in a target object, and receiving 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 the first ultrasonic wave and the second ultrasonic wave have a first pulse repetition frequency, the third ultrasonic wave and the fourth ultrasonic wave have a second pulse repetition frequency, and the first pulse repetition frequency and the second pulse repetition frequency are non-integer multiples; transmitting a fifth ultrasonic wave, a sixth ultrasonic wave, a seventh ultrasonic wave, and an eighth ultrasonic wave toward the blood flow location to be measured at a second transmitting angle different from the first transmitting angle, and receiving 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 is provided between the fifth ultrasonic wave and the sixth ultrasonic wave, a fourth pulse repetition frequency is provided 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 multiples; Obtaining a first projection component of a 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 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 of the blood flow position to be measured at 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; The first projection component and the second projection component are synthesized to obtain a blood flow velocity vector of the blood flow position to be measured.

10. The method according to claim 9, characterized in that The first pulse repetition frequency and the second pulse repetition frequency are mutually prime, and the third pulse repetition frequency and the fourth pulse repetition frequency are mutually prime.

11. The method according to claim 9, characterized in that 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 ultrasound waves propagating in the blood flow to be measured.

12. The method according to claim 9, characterized in that 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.

13. The method according to any one of claims 9 to 12, 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 unfocused ultrasonic waves, and the method further includes: transmitting focused ultrasound waves to the blood flow position to be measured, and receiving echoes of the focused ultrasound waves to obtain focused echo signals; generating a grayscale image of the blood flow position to be measured based on the focused echo signal; generating a blood flow velocity vector diagram based on the blood flow velocity vector at the blood flow position to be measured; The grayscale image is displayed and the blood flow velocity vector diagram is superimposed on the grayscale image.

14. The method according to claim 13, characterized in that 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; or 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 transmission time interval, and the focused ultrasound wave is transmitted between two ultrasound waves corresponding to the maximum transmission time interval.

15. The method according to claim 9, characterized in that The method further comprises: transmitting a ninth ultrasonic wave, a tenth ultrasonic wave, an eleventh ultrasonic wave, and a twelfth ultrasonic wave toward the blood flow location to be measured at a third transmission angle different from the first transmission angle and the second transmission angle, and receiving echoes of the ultrasonic waves to obtain a ninth echo signal, a tenth echo signal, an eleventh echo signal, and a twelfth echo signal; wherein a fifth pulse repetition frequency is provided between the ninth ultrasonic wave and the tenth ultrasonic wave, a sixth pulse repetition frequency is provided between the eleventh ultrasonic wave and the twelfth ultrasonic wave, and the fifth pulse repetition frequency and the sixth pulse repetition frequency are non-integer multiples of each other; obtaining, 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, a third projection component of the blood flow velocity vector at the blood flow position to be measured at the third transmission angle; 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: The first projection component, the second projection component and the third projection component are synthesized to obtain a three-dimensional blood flow velocity vector of the blood flow position to be measured.

16. An ultrasonic blood flow imaging method, characterized in that: The method comprises: Transmitting a first ultrasonic wave, a second ultrasonic wave, and a third ultrasonic wave at a first transmission angle toward a blood flow location to be measured in 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 the first ultrasonic wave and the second ultrasonic wave have a first pulse repetition frequency, the second ultrasonic wave and the third ultrasonic wave have a second pulse repetition frequency, and the first pulse repetition frequency and the second pulse repetition frequency are non-integer multiples; transmitting a fourth ultrasonic wave, a fifth ultrasonic wave, a sixth ultrasonic wave, and a seventh ultrasonic wave toward the blood flow location to be measured at a second transmitting angle different from the first transmitting angle, 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 a third pulse repetition frequency is provided between the fourth ultrasonic wave and the fifth ultrasonic wave, a fourth pulse repetition frequency is provided between the sixth ultrasonic wave and the seventh ultrasonic wave, and the third pulse repetition frequency and the fourth pulse repetition frequency are non-integer multiples; 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 first pulse repetition frequency, and the second 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 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; The first projection component and the second projection component are synthesized to obtain a blood flow velocity vector of the blood flow position to be measured.

17. The method according to claim 16, characterized in that The method further comprises: transmitting an eighth ultrasonic wave, a ninth ultrasonic wave, and a tenth ultrasonic wave toward the blood flow location to be measured at a third transmission angle different from the first transmission angle and the second transmission angle, and receiving echoes of the ultrasonic waves to obtain an eighth echo signal, a ninth echo signal, and a tenth echo signal; wherein a fifth pulse repetition frequency is provided between the eighth ultrasonic wave and the ninth ultrasonic wave, a sixth pulse repetition frequency is provided between the ninth ultrasonic wave and the tenth ultrasonic wave, and the fifth pulse repetition frequency and the sixth pulse repetition frequency are non-integer multiples of each other; obtaining a third projection component of the blood flow velocity vector of the blood flow position to be measured at the third transmission 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 blood flow position to be measured includes: The first projection component, the second projection component and the third projection component are synthesized to obtain a three-dimensional blood flow velocity vector of the blood flow position to be measured.

18. The method according to claim 16, characterized in that The method further comprises: transmitting an eighth ultrasonic wave, a ninth ultrasonic wave, a tenth ultrasonic wave, and an eleventh ultrasonic wave toward the blood flow location to be measured at a third transmission angle different from the first transmission angle and the second transmission angle, and receiving 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 a fifth pulse repetition frequency is provided between the eighth ultrasonic wave and the ninth ultrasonic wave, a sixth pulse repetition frequency is provided between the tenth ultrasonic wave and the eleventh ultrasonic wave, and the fifth pulse repetition frequency and the sixth pulse repetition frequency are non-integer multiples of each other; obtaining, 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, a third projection component of the blood flow velocity vector at the blood flow position to be measured at the third transmission angle; 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: The first projection component, the second projection component and the third projection component are synthesized to obtain a three-dimensional blood flow velocity vector of the blood flow position to be measured.

19. An ultrasonic imaging device, characterized in that: The device includes a transmitting circuit, a receiving circuit, an ultrasound probe and a processor, wherein: The transmitting circuit is used to control the ultrasonic probe to transmit ultrasonic waves toward the blood flow position to be measured in the target object; The receiving circuit is used to control the ultrasonic probe to receive the echo of the ultrasonic wave and obtain an echo signal from the echo of the ultrasonic wave; The processor is configured to perform ultrasonic blood flow imaging based on the echo signal; The processor is further configured to execute the ultrasonic blood flow imaging method according to any one of claims 1 to 18.

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