Ultrasonic plane wave harmonic imaging method, medium and electronic device

Abstract

The present application provides an ultrasonic plane wave harmonic imaging method, medium and electronic device. The method includes: controlling a linear array with array elements to perform transmission and reception acquisition, determining angle plane waves for imaging, calculating the excitation delays corresponding to each angle plane wave, and obtaining the plane wave delay excitation of a total of groups of array elements; repeating each plane wave delay excitation times to form an excitation group, arranging these excitation groups to form a total of different transmission encodings; using the generated different transmission encodings to perform positive pulse and negative pulse transmissions respectively, and obtaining the encoded transmission echo data of a total of groups of channels; performing specific harmonic decoding on the encoded transmission echo data to obtain the harmonic echo data transmitted by the angle plane waves; respectively performing frequency domain beamforming and signal processing on the harmonic echo data of the angle plane waves to obtain the final ultrasonic image. The present application can improve the signal-to-noise ratio of the harmonic components in the plane wave echo signal.

Description

Technical Field

[0001] This application relates to the field of ultrasonic imaging technology, and particularly to an ultrasonic plane wave harmonic imaging method, medium and electronic device. Background Art

[0002] Harmonic imaging and plane wave imaging are two important ultrasonic imaging technologies.

[0003] Harmonic imaging refers to a technology that uses the harmonic components in ultrasonic echoes for imaging. Due to the nonlinear characteristics of biological tissues, ultrasonic waves generate harmonic components when propagating in the human body, and their frequencies are integer multiples of the transmitted ultrasonic frequency. Using harmonic components for imaging has many advantages, including improving imaging resolution, suppressing side lobes, eliminating reverberation artifacts, and reducing the thickness of the imaging section.

[0004] Plane wave imaging is a technology that images by transmitting plane waves with different inclination angles. The images of multiple angle plane waves are coherently superimposed to achieve a pixel-level focusing effect. Compared with the traditional line-by-line focusing scan mode that requires hundreds of transmissions to obtain an image, plane wave imaging can complete one imaging with only several to more than a dozen transmissions, so it can achieve an extremely high imaging frame rate.

[0005] Combining the harmonic technology and the plane wave technology can simultaneously obtain high frame rate, high resolution, and high contrast, which is an effective method to achieve high-quality ultrasonic imaging and improve ultrasonic imaging diagnosis.

[0006] However, the nonlinear characteristics of biological tissues are not particularly significant, and coupled with the frequency dependence of ultrasonic attenuation, the energy of the harmonic components is much lower than that of the fundamental wave components, resulting in an extremely low signal-to-noise ratio of the harmonic signals and a very limited imaging depth in the harmonic mode. Summary of the Invention

[0007] The purpose of this application is to provide an ultrasonic plane wave harmonic imaging method, medium and electronic device, which can at least partially solve the above technical problems existing in the prior art.

[0008] One aspect of this application provides an ultrasonic plane wave harmonic imaging method. The method includes: controlling a linear array with transducer elements to perform transmission and reception acquisition, determining angle plane waves for imaging, calculating the excitation delays corresponding to each angle plane wave, and obtaining a total of groups of plane wave delay excitations of the array elements; repeating each plane wave delay excitation times to form an excitation group, arranging the excitation groups, and forming a total of different transmission encodings; using the generated Different transmit encodings are respectively used for positive pulse and negative pulse transmissions to obtain a total of groups of encoded transmit echo data for the channels; performing specific harmonic decoding on the encoded transmit echo data to obtain harmonic echo data for angle plane wave transmissions at angles; respectively performing frequency-domain beamforming and signal processing on the harmonic echo data for the

[0009] angle plane waves to obtain the final ultrasound image. Furthermore, repeating the delay excitation of each plane wave times to form an excitation group, and arranging the excitation groups to form a total of different transmit encodings, including: repeating the delay excitation of each plane wave at intervals times to form an excitation group, and arranging the excitation groups at intervals in a predetermined order in time to form a total of

[0010] different transmit encodings. Furthermore, arranging the excitation groups at intervals in a predetermined order in time to form a total of different transmit encodings, including: arranging the excitation groups at intervals in time according to the polling preposition method to generate

[0011] different transmit encodings, wherein arranging according to the polling preposition method includes: for the th transmit encoding, placing the th excitation group before other excitation groups in time, while other excitation groups are arranged in the original order, where is a positive integer not greater than

[0012] Furthermore, using the generated different transmit encodings for positive pulse and negative pulse transmissions respectively includes: after each positive pulse transmission using any one of the generated different transmit encodings, following it with a negative pulse transmission using the same transmit encoding.

[0013] Furthermore, performing specific harmonic decoding on the encoded transmit echo data to obtain Harmonic echo data emitted by plane waves at multiple angles, including: adding the coded emission echo data of adjacent positive and negative pulses, eliminating the fundamental wave information, and only leaving the harmonic echo data; performing Fourier transform on the harmonic echo data, and constructing a frequency-domain linear equation set according to the emission coding; solving the linear equation sets at each frequency within the harmonic frequency band of the transducer to obtain the harmonic echo frequency-domain data separately excited by plane waves at each angle.

[0014] Further, the constructing of the frequency-domain linear equation set according to the emission coding includes: constructing the frequency-domain linear equation of the th emission coding through the following formula:

[0015]

[0016]

[0017]

[0018] Wherein, represents the frequency-domain echo data of the th emission coding, represents the frequency-domain harmonic echo data corresponding to the th plane wave at an angle, represents the phase rotation multiplier corresponding to the th repetition within the excitation group, represents the phase rotation multiplier corresponding to adjacent excitation groups, represents the imaginary unit, represents the angular frequency of the Fourier transform.

[0019] Further, the solving of the linear equation sets at each frequency within the harmonic frequency band of the transducer includes: if the harmonic frequency band of the transducer is , then it is default that the frequency components of the echo data outside the interval are 0.

[0020] Wherein, the frequency-domain beamforming of the harmonic echo data of the plane waves at an angle respectively includes: performing frequency-domain beamforming on the harmonic echo data of the plane waves at an angle respectively within .

[0021] Further, the calculating of the excitation delay corresponding to each plane wave at an angle includes:

[0022] Calculating the excitation delay corresponding to the th transducer element for the th plane wave at an angle through the following formula:

[0023]

[0024] Among them, represents the excitation delay corresponding to the th angular plane wave of the th transducer element, represents the inclination angle of the th angular plane wave, represents the abscissa of the th transducer element, represents the estimated sound speed of the imaging area;

[0025] All excitation delays of all transducer elements during the emission of

[0026] all angular plane waves are calculated according to the above formula.

[0027] Another aspect of the present application provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the above-mentioned ultrasonic plane wave harmonic imaging method are implemented.

[0028] The ultrasonic plane wave harmonic imaging method, medium and electronic device according to one or more embodiments of the present application apply coded excitation to plane wave harmonic imaging, thereby significantly increasing the energy of ultrasonic waves emitted per unit time, decoding harmonics in the frequency domain and performing beam synthesis, and significantly improving the signal-to-noise ratio of harmonic signals and increasing the imaging depth on the premise of ensuring high frame rate, high resolution and high contrast. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic flowchart of an ultrasonic plane wave harmonic imaging method according to an embodiment of the present application.

[0030] Figure 2 is a schematic diagram showing the correspondence between the plane wave emission angle and its excitation delay according to an embodiment of the present application.

[0031] Figure 3 is a schematic flowchart of generating an emission code according to the polling preposition method according to an embodiment of the present application.

[0032] Figure 4 is a comparison schematic diagram of positive and negative pulse excitations according to an embodiment of the present application.

[0033] Figure 5Schematic diagram of positive and negative pulse transmissions using three emission encodings respectively according to an embodiment of the present application.

[0034] Figure 6 Schematic block diagram of an electronic device according to an embodiment of the present application. Detailed implementation manners

[0035] Here, exemplary embodiments will be described in detail, and examples thereof are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of devices consistent with some aspects of the present application as detailed in the appended claims.

[0036] Ultrasound plane wave harmonic imaging is an imaging technique with high frame rate, high resolution, and high contrast. However, due to the low amplitude of the harmonic component and poor signal-to-noise ratio, the imaging depth of harmonic imaging is limited, which in turn hinders doctors from making reliable diagnoses of deep tissues.

[0037] The coded excitation technique can transmit more signal energy in the same time by transmitting ultrasonic waves with a specific coding form. Therefore, the average transmission power can be significantly increased, and the signal-to-noise ratio of the echo signal can be improved. The present application provides an ultrasound plane wave harmonic imaging method. By applying coded excitation to plane wave harmonic imaging, the disadvantage of poor signal-to-noise ratio can be overcome, and the practical value of this technique can be improved.

[0038] Next, in conjunction with the drawings, the ultrasound plane wave harmonic imaging methods, media, and electronic devices of various embodiments of the present application will be described in detail. Without conflict, the features in the following embodiments and implementation manners can be combined with each other.

[0039] Figure 1 Disclosed is a flowchart of an ultrasound plane wave harmonic imaging method according to an embodiment of the present application. As Figure 1 shown, the ultrasound plane wave harmonic imaging method according to an embodiment of the present application may include steps S1 to S5.

[0040] Step S1: Control a linear array with transducer elements to perform transmission and reception acquisitions, determine angle plane waves for imaging, calculate the excitation delays corresponding to each angle plane wave, and obtain a total of groups of plane wave delay excitations for the array elements.

[0041] Figure 2 Disclosed is a schematic diagram of the correspondence between the plane wave emission angle and its excitation delay according to an embodiment of the present application. AsFigure 2 As shown, to make the linear array emit a plane wave at a specific angle, it is necessary to apply excitations to each transducer element at different time points.

[0042] Suppose the tilt angle of the th plane wave is Then, the excitation delay corresponding to the th angle plane wave of the

[0043] th transducer element can be calculated by the following formula (1):

[0044] Wherein, represents the excitation delay corresponding to the th angle plane wave of the th transducer element, represents the tilt angle of the th angle plane wave, represents the abscissa of the th transducer element, represents the estimated sound speed of the imaging region.

[0045] Furthermore, by calculating according to the above formula (1), the excitation delays of all transducer elements during the emission of all angle plane waves can be obtained.

[0046] Step S2: Repeat the delayed excitation of each plane wave times to form an excitation group, and arrange these excitation groups to form a total of different transmission codes.

[0047] In some embodiments, the delayed excitation of each plane wave is repeated at intervals of to form an excitation group, and then these excitation groups are arranged at intervals of in time according to a predetermined order to form a total of different transmission codes. different transmission codes.

[0048] Optionally, the excitation groups can be arranged at intervals of in time according to the polling preposition method to generate different transmission codes.

[0049] Arranging according to the polling preposition method includes: for the th transmission code, placing the th excitation group before other excitation groups in time, while other excitation groups are arranged in the original order, where is not greater than positive integers

[0050] Figure 3 FIG. shows a schematic flow chart of generating transmission codes according to the polling preposition method in an embodiment of the present application. Among them, Figure 3 shows in three different angular plane waves (i.e., ), and each angular plane wave is repeated twice (i.e., ), the process of generating three different transmission codes is as follows:

[0051] As shown in Figure 3 , first, each angular plane wave is excited and repeated twice at intervals of , that is, the first angular plane wave is excited and repeated twice, the second angular plane wave is excited and repeated twice, and the third angular plane wave is excited and repeated twice, to obtain three excitation groups, namely the first angular excitation group, the second angular excitation group, and the third angular excitation group.

[0052] Then, these three excitation groups are arranged in time at intervals of according to the polling preposition method to obtain three transmission codes.

[0053] For the first type of transmission code, the first angular excitation group is arranged at the first place, followed by the second angular excitation group and the third angular excitation group.

[0054] For the second type of transmission code, the second angular excitation group is arranged at the first place, followed by the first angular excitation group and the third angular excitation group.

[0055] For the third type of transmission code, the third angular excitation group is arranged at the first place, followed by the first angular excitation group and the second angular excitation group.

[0056] Step S3: Use the generated different transmission codes to perform positive pulse and negative pulse transmissions respectively, to obtain a total of groups of channel encoded echo data.

[0057] By changing the polarity of the excitation signal, positive and negative pulse excitations can be obtained. Figure 4 FIG. shows a comparison schematic diagram of positive and negative pulse excitations in an embodiment of the present application. As shown in Figure 4 , among them, the solid line represents positive pulse excitation, and the dashed line represents negative pulse excitation.

[0058] In step S3, each time the generated After the positive pulse emission of any one of the different emission encodings, a negative pulse emission using the same emission encoding follows. That is, for each emission encoding, first a positive pulse emission and reception acquisition are performed, and then a negative pulse emission and reception acquisition are performed.

[0059] Figure 5 Disclosed is the use in one embodiment of the present application Figure 3 Schematic diagrams of positive and negative pulse emissions respectively performed using the three emission encodings shown. As Figure 5 shown, for Figure 3 the case of the three emission encodings shown (i.e., ), the first emission can be a positive pulse emission of the first emission encoding, the second emission can be a negative pulse emission of the first emission encoding, the third emission can be a positive pulse emission of the second emission encoding, the fourth emission can be a negative pulse emission of the second emission encoding, the fifth emission can be a positive pulse emission of the third emission encoding, and the sixth emission can be a negative pulse emission of the third emission encoding. A total of six emissions and reception acquisitions are performed.

[0060] Step S4: Perform specific harmonic decoding on the encoded emission echo data to obtain harmonic echo data of angle plane wave emissions.

[0061] In some embodiments, step S4 may include steps S41 to S43.

[0062] In step S41, add the encoded emission echo data of two adjacent positive and negative pulse emissions. The change in excitation polarity only changes the polarity of the fundamental wave, but does not change the polarity of the harmonics. Therefore, adding in this way will cancel out the fundamental wave information and only leave the harmonic echo data.

[0063] In step S42, perform a Fourier transform on the harmonic echo data and construct a frequency-domain linear equation set according to the emission encoding.

[0064] In some embodiments, the frequency-domain linear equation of the th emission encoding can be constructed by the following formula (2):

[0065] (2)

[0066] Wherein, represents the frequency-domain echo data of the th emission encoding, represents the frequency-domain harmonic echo data corresponding to the th angle plane wave, represents the phase rotation multiplier corresponding to times of repetition within the excitation group, Represents the phase rotation multiplier corresponding to adjacent excitation groups.

[0067] It can be given by the following formula (3):

[0068] (3)

[0069] Wherein, represents the imaginary unit, represents the angular frequency of the Fourier transform.

[0070] It can be given by the following formula (4):

[0071] (4)

[0072] In step S43, a linear equation system at each frequency is solved within the harmonic frequency band of the transducer to obtain the harmonic echo frequency domain data of each angular plane wave excited separately.

[0073] If the harmonic frequency band of the transducer is , then it is defaulted that the echo data frequency components outside the interval are 0.

[0074] Step S5: Perform frequency domain beamforming and signal processing on the harmonic echo data of angular plane waves respectively to obtain the final ultrasonic image.

[0075] Specifically, perform frequency domain beamforming on the harmonic echo data of angular plane waves respectively within , without performing inverse Fourier transform to obtain time domain echo data. Then perform processing such as coherent superposition, envelope extraction, logarithmic compression, etc., so as to obtain the final ultrasonic image.

[0076] It can be understood that Figure 1 the steps S1 to S5 shown are only names given to each step for distinguishing each step, and do not represent the execution sequence of the steps.

[0077] The ultrasonic plane wave harmonic imaging method of the present application applies coded excitation to plane wave harmonic imaging, thereby significantly increasing the energy of the ultrasonic wave emitted per unit time, decoding harmonics in the frequency domain and performing beamforming, and significantly improving the signal-to-noise ratio of the harmonic signal and increasing the imaging depth on the premise of ensuring high frame rate, high resolution, and high contrast.

[0078] The present application also provides a computer-readable storage medium. A computer program is stored on this storage medium, and when the computer program is executed by a processor, it implements the above Figure 1Steps of the ultrasonic plane wave harmonic imaging method shown

[0079] This application also provides an electronic device 600. Figure 6 The schematic block diagram of the electronic device 600 according to an embodiment of this application is disclosed. As Figure 6 shown, the electronic device 600 according to an embodiment of this application includes a processor 601, an internal bus 602, a network interface 603, a memory 604, and a non-volatile memory 605. Of course, it may also include other hardware required for other services. The processor 601 can read the corresponding computer program from the non-volatile memory 605 into the memory 604 and then run it to implement the steps of the ultrasonic plane wave harmonic imaging method as described above. Of course, in addition to the software implementation method, this application does not exclude other implementation methods, such as logic devices or a combination of software and hardware, etc. That is to say, the execution subject of the following processing flow is not limited to each logic unit, and can also be hardware or a logic component.

[0080] It can be understood that for the convenience of description, the above device is described by function and divided into each module for description. Of course, when implementing this application, the functions of each module can also be implemented in the same or multiple software and / or hardware.

[0081] The ultrasonic plane wave harmonic imaging method, medium, and electronic device according to one or more embodiments of this application can at least have the following beneficial technical effects:

[0082] (1) The encoding scheme used is simple and effective;

[0083] (2) By adding positive and negative pulses to cancel the fundamental wave component, the aliasing of the fundamental wave and harmonic waves is avoided, and the amplitude of the harmonic component is increased by 2 times (the signal-to-noise ratio is times);

[0084] (3) By including the excitation of all M angle plane waves in one emission, the amplitude of the harmonic component is further increased by 2M times (the signal-to-noise ratio is times);

[0085] (4) By repeating K times within the excitation group of each angle plane wave, the amplitude of the harmonic component is further increased by 2MK times (the signal-to-noise ratio is times);

[0086] (5) By decoding and beamforming within the harmonic frequency band, the calculation is simplified.

[0087] The above has introduced in detail the ultrasonic plane wave harmonic imaging method, medium and electronic device provided by the embodiments of the present application. Specific examples are used in this article to elaborate on the ultrasonic plane wave harmonic imaging method, medium and electronic device of the embodiments of the present application. The description of the above embodiments is only used to help understand the core idea of the present application and is not intended to limit the present application. It should be noted that for those of ordinary skill in the art of this technology, without departing from the spirit and principle of the present application, several improvements and modifications can still be made to the present application, and these improvements and modifications should also fall within the protection scope of the appended claims of the present application.

Claims

1. An ultrasonic plane wave harmonic imaging method, characterized in that: include: Control has A linear array of transducer elements is used to transmit and receive data to determine the The excitation delay corresponding to each angle plane wave is calculated to obtain the total Group Plane wave delayed excitation of array elements; Repeat each plane wave delay excitation The excitation groups are arranged to form a total Different transmission codes, including: Each plane wave delay excitation is pressed Spaced Repetition times to form an excitation group, and the excitation group is pressed The intervals are arranged in a predetermined order in time to form a common Different transmission codes; Use the generated Different transmission codes are used to transmit positive pulses and negative pulses respectively, and the Group The channel's coded transmission echo data; The coded transmission echo data is harmonically decoded to obtain Harmonic echo data for plane wave transmission at each angle, including: Add the coded transmission echo data of two adjacent positive pulses and negative pulses, eliminate the fundamental wave information, and only leave the harmonic echo data; Performing Fourier transformation on the harmonic echo data, and constructing a frequency domain linear equation group according to the transmission code; Solve the linear equations of each frequency in the harmonic frequency band of the transducer to obtain the frequency domain data of harmonic echoes excited by plane waves at each angle; right The harmonic echo data of the plane wave at each angle are subjected to frequency domain beam synthesis and signal processing to obtain the final ultrasound image. The following formula is used to construct the The frequency domain linear equation of the transmit code is: in, Representative The frequency domain echo data of the transmitted code is Representative The frequency domain harmonic echo data corresponding to the plane wave of angles, Represents the incentive group The phase rotation multiplier corresponding to the repetition is, represents the phase rotation multiplier corresponding to adjacent excitation groups, represents the imaginary unit, represents the angular frequency of the Fourier transform, The linear equations for solving each frequency in the harmonic frequency band of the transducer include: If the harmonic frequency band of the transducer is , then by default The frequency component of the echo data outside the interval is 0. Among them, the Frequency domain beam synthesis is performed on the harmonic echo data of the plane wave at each angle, including: The harmonic echo data of the plane wave at each angle are respectively Frequency domain beamforming is performed within the 2. The method according to claim 1, characterized in that: The excitation group is The intervals are arranged in a predetermined order in time to form a common Different transmission codes, including: The stimulus group is pressed The intervals are arranged in time according to the patrol-precedence method, generating Different transmission codes, The arrangement according to the round-robin method includes: for the first The transmission code is The stimulus group is placed before the other stimulus groups in time, and the other stimulus groups are arranged in the original order, among which, Not greater than A positive integer.

3. The method according to claim 2, characterized in that: The use of the generated Different transmission codes for positive pulse and negative pulse transmission include: Each time you use the generated After the positive pulse transmission of any one of the different transmission codes, a negative pulse transmission using the same transmission code follows.

4. The method according to claim 1, characterized in that: The calculation of the excitation delay corresponding to the plane waves at each angle comprises: The following formula is used to calculate the The first The excitation delay corresponding to the plane wave of angles is: in, Representative The first The excitation delay corresponding to the plane wave of angles is: Representative The inclination angle of the plane wave is Representative The horizontal coordinate of the transducer array element, represents the estimated speed of sound in the imaging area; According to the above formula, we can calculate all All the angles of the plane wave launch The excitation delay of each transducer array element.

5. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the ultrasonic plane wave harmonic imaging method according to any one of claims 1 to 4 are implemented.

6. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the ultrasonic plane wave harmonic imaging method according to any one of claims 1 to 4 are implemented.

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