Ultrasound diagnostic apparatus and ultrasound diagnostic method

Abstract

To improve image quality.SOLUTION: An ultrasound diagnostic apparatus according to an embodiment includes: a transmission / reception unit; a design unit; a first analysis unit; a second analysis unit; and a reconstruction unit. The transmission / reception unit transmits ultrasound to a subject under a first transmission condition and receives echoes from the subject. The design unit generates a second transmission condition corresponding to the transmission of ultrasound to which a harmonic component is added, on the basis of the first transmission condition. The first analysis unit forward-propagates ultrasound transmitted on the basis of the second transmission condition to obtain a transmission wave field. The second analysis unit back-propagates signals based on the echoes to obtain a reception wave field. The reconstruction unit performs correlation analysis between the transmission wave field and the reception wave field to generate harmonic echo components.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The embodiments disclosed in the present specification and drawings relate to an ultrasound diagnostic apparatus and an ultrasound diagnostic method. [Background technology]

[0002] Seismic interferometry (also known as SPM (Shot-Profile Migration) or wavefield correlation method) is known in the field of seismic wave measurement. Seismic interferometry is a method for reconstructing the location of an underground earthquake source and reflection surfaces, and estimates the location of the earthquake source by performing correlation processing between the transmitted wave field simulated by forward propagation and the received wave field simulated by reverse propagation.

[0003] Here, since seismic waves and ultrasound waves have in common the fact that they are elastic waves, it is conceivable that seismic interferometry could be used for image reconstruction in an ultrasound diagnostic apparatus to reconstruct an ultrasound image.

[0004] In ultrasound diagnostic equipment, a technique called harmonic imaging, which extracts and visualizes harmonic components in echoes, is widely used. Harmonic imaging is an important technique because it enables the suppression of echo components from undesired directions. Therefore, when applying seismic interferometry to image reconstruction in ultrasound diagnostic equipment, it is desirable to be able to perform harmonic imaging.

[0005] However, simply applying seismic interferometry or SPM to image reconstruction in ultrasound diagnostic equipment does not take into account the harmonic components generated during the ultrasound propagation process, making it impossible to extract and visualize the harmonic components in the echo, and so some ingenuity is required. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2014 / 167698 [Non-patent literature]

[0007] [Non-Patent Document 1] “Distributed Aberration Correction Techniques Based on Tomographic Sound Speed ​​Estimates”, R. Ali et al., IEEE T-UFFC, Vol. 69, No. 5, p1714, May 2022 Summary of the Invention [Problem to be solved by the invention]

[0008] One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to improve image quality. However, the problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above problem. Problems corresponding to the effects of each configuration shown in the embodiments described later can also be positioned as other problems. [Means for solving the problem]

[0009] An ultrasound diagnostic device according to an embodiment includes a transmitting / receiving unit, a design unit, a first analysis unit, a second analysis unit, and a reconstruction unit. The transmitting / receiving unit transmits ultrasound to a subject under a first transmission condition and receives an echo from the subject. The design unit creates a second transmission condition corresponding to transmission of ultrasound in which a harmonic component is added to the ultrasound, based on the first transmission condition. The first analysis unit forward propagates the ultrasound transmitted based on the second transmission condition to obtain a transmitted wave field. The second analysis unit back propagates a signal based on the echo to obtain a received wave field. The reconstruction unit performs correlation analysis between the transmitted wave field and the received wave field to generate a harmonic echo component. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of an ultrasonic diagnostic apparatus according to the first embodiment. [Diagram 2]FIG. 2 is a diagram illustrating the processing performed by the ultrasound diagnostic apparatus 10 according to the first embodiment. [Diagram 3] FIG. 3 is a flowchart illustrating the flow of processing performed by the ultrasound diagnostic apparatus according to the first embodiment. [Figure 4] FIG. 4 is a diagram illustrating the processing performed by the ultrasound diagnostic apparatus according to the first embodiment. [Diagram 5] FIG. 5 is a flowchart illustrating the flow of processing performed by the ultrasound diagnostic apparatus according to the first embodiment. [Figure 6] FIG. 6 is a flowchart illustrating the flow of processing performed by the ultrasound diagnostic apparatus according to the second embodiment. [Figure 7] FIG. 7 is a diagram illustrating the processing performed by the ultrasound diagnostic apparatus according to the second embodiment. [Figure 8] FIG. 8 is a diagram illustrating the processing performed by the ultrasound diagnostic apparatus according to the second embodiment. [Figure 9] FIG. 9 is a flowchart illustrating the flow of processing performed by an ultrasound diagnostic apparatus according to a modified example of the second embodiment. [Figure 10] FIG. 10 is a diagram illustrating a process performed by an ultrasonic diagnostic apparatus according to a modified example of the second embodiment. [Figure 11] FIG. 11 is a flowchart illustrating the flow of processing performed by the ultrasound diagnostic apparatus according to the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] (First embodiment) First, the configuration of an ultrasonic diagnostic apparatus according to the first embodiment will be described. Fig. 1 is a block diagram showing an example of the configuration of an ultrasonic diagnostic apparatus according to the first embodiment. As shown in Fig. 1, the ultrasonic diagnostic apparatus according to the first embodiment includes an ultrasonic probe 5 and an ultrasonic diagnostic apparatus 10. The ultrasonic diagnostic apparatus 10 includes a transmission circuit 9, a reception circuit 11, and a medical image processing apparatus 100.

[0012] The ultrasonic probe 5 has a plurality of piezoelectric transducers, which generate ultrasonic waves based on a drive signal supplied from a transmission circuit 9 of the ultrasonic diagnostic device 10 described later. The plurality of piezoelectric transducers of the ultrasonic probe 5 receive reflected waves from the subject P and convert them into electrical signals (reflected wave signals). The ultrasonic probe 5 also has a matching layer provided on the piezoelectric transducers, a backing material that prevents ultrasonic waves from propagating backward from the piezoelectric transducers, and the like. The ultrasonic probe 5 is detachably connected to the ultrasonic diagnostic device 10.

[0013] When ultrasonic waves are transmitted from the ultrasonic probe 5 to the subject P, the transmitted ultrasonic waves are successively reflected by discontinuous surfaces of acoustic impedance in the internal tissues of the subject P, and are received as reflected waves by a plurality of piezoelectric transducers of the ultrasonic probe 5, and converted into reflected wave signals. The amplitude of the reflected wave signal depends on the difference in acoustic impedance at the discontinuous surfaces where the ultrasonic waves are reflected. When the transmitted ultrasonic pulse is reflected by the surface of a moving blood flow, heart wall, or the like, the reflected wave signal undergoes a frequency shift due to the Doppler effect depending on the velocity component of the moving body in the ultrasonic transmission direction.

[0014] The embodiment is applicable whether the ultrasonic probe 5 is a 1D array probe that scans the subject P two-dimensionally, or a mechanical 4D probe or a 2D array probe that scans the subject P three-dimensionally.

[0015] The ultrasonic diagnostic device 10 is a device that generates ultrasonic image data based on a reflected wave signal received from the ultrasonic probe 5. The ultrasonic diagnostic device 10 shown in Fig. 1 is a device that can generate two-dimensional ultrasonic image data based on a two-dimensional reflected wave signal, and can generate three-dimensional ultrasonic image data based on a three-dimensional reflected wave signal. However, the embodiment is also applicable to cases where the ultrasonic diagnostic device 10 is a device dedicated to two-dimensional data.

[0016] As shown in FIG. 1, the ultrasound diagnostic apparatus 10 includes a transmission circuit 9, a reception circuit 11, and a medical image processing apparatus 100.

[0017] The transmission circuit 9 and the reception circuit 11 control the ultrasonic transmission and reception performed by the ultrasonic probe 5 based on instructions from a processing circuit 150 having a control function 150f described later. The transmission circuit 9 has a pulse generator, a transmission delay unit, a pulser, etc., and supplies a drive signal to the ultrasonic probe 5. The pulse generator repeatedly generates a rate pulse for forming a transmission ultrasonic wave at a predetermined pulse repetition frequency (PRF: Pulse Repetition Frequency). In addition, the transmission delay unit focuses the ultrasonic waves generated from the ultrasonic probe 5 into a beam shape and provides a delay time for each piezoelectric transducer required to determine the transmission directivity to each rate pulse generated by the pulse generator. In addition, the pulser applies a drive signal (drive pulse) to the ultrasonic probe 5 at a timing based on the rate pulse.

[0018] That is, the transmission delay unit arbitrarily adjusts the transmission direction of the ultrasonic waves transmitted from the piezoelectric transducer surface by changing the delay time given to each rate pulse. Also, the transmission delay unit controls the position of the focal point (transmission focus) in the depth direction of the ultrasonic transmission by changing the delay time given to each rate pulse.

[0019] The transmission circuit 9 has a function of instantaneously changing the transmission frequency, transmission drive voltage, etc., in order to execute a predetermined scan sequence based on instructions from the processing circuit 150 described later. In particular, the change in the transmission drive voltage is realized by a linear amplifier type oscillation circuit that can instantaneously switch its value, or a mechanism that electrically switches between multiple power supply units.

[0020] The receiving circuit 11 has an amplifier circuit, an A / D (Analog / Digital) converter, a reception delay circuit, an adder, a quadrature detection circuit, etc., and performs various processes on the reflected wave signal received from the ultrasonic probe 5 to generate a received signal (reflected wave data). The amplifier circuit amplifies the reflected wave signal for each channel and performs a gain correction process. The A / D converter A / D converts the gain-corrected reflected wave signal. The reception delay circuit provides the digital data with a reception delay time required to determine the reception directivity. The adder performs an addition process of the reflected wave signal to which the reception delay time has been provided by the reception delay circuit. The addition process of the adder emphasizes the reflected component from the direction according to the reception directivity of the reflected wave signal. Then, the quadrature detection circuit converts the output signal of the adder into an in-phase signal (I signal, I: In-phase) and a quadrature signal (Q signal, Q: Quadrature-phase) of the baseband. Then, the quadrature detection circuit transmits the I signal and the Q signal (hereinafter referred to as IQ signal) to the processing circuit 150 as a received signal (reflected wave data). The quadrature detection circuit may convert the output signal of the adder into an RF (Radio Frequency) signal and transmit it to the processing circuit 150. The IQ signal and the RF signal are received signals having phase information.

[0021] When scanning a two-dimensional region in the subject P, the transmission circuit 9 causes the ultrasonic probe 5 to transmit an ultrasonic beam for scanning the two-dimensional region. Then, the reception circuit 11 generates a two-dimensional reception signal from the two-dimensional reflected wave signal received from the ultrasonic probe 5. When scanning a three-dimensional region in the subject P, the transmission circuit 9 causes the ultrasonic probe 5 to transmit an ultrasonic beam for scanning the three-dimensional region. Then, the reception circuit 11 generates a three-dimensional reception signal from the three-dimensional reflected wave signal received from the ultrasonic probe 5. The reception circuit 11 generates a reception signal based on the reflected wave signal, and transmits the generated reception signal to the processing circuit 150.

[0022] The transmission circuit 9 causes the ultrasonic probe 5 to transmit an ultrasonic beam from a predetermined transmission position (transmission scanning line). The reception circuit 11 receives a signal due to a reflected wave of the ultrasonic beam transmitted by the transmission circuit 9 from the ultrasonic probe 5 at a predetermined reception position (reception scanning line). When parallel simultaneous reception is not performed, the transmission scanning line and the reception scanning line are the same scanning line. On the other hand, when parallel simultaneous reception is performed, when the transmission circuit 9 causes the ultrasonic probe 5 to transmit one ultrasonic beam on one transmission scanning line, the reception circuit 11 simultaneously receives the signal due to the reflected wave originating from the ultrasonic beam transmitted by the transmission circuit 9 to the ultrasonic probe 5 as multiple reception beams at multiple predetermined reception positions (reception scanning lines) through the ultrasonic probe 5.

[0023] The medical image processing device 100 is connected to a transmission circuit 9 and a reception circuit 11, and processes signals received from the reception circuit 11 and controls the transmission circuit 9. The medical image processing device 100 includes a processing circuit 150, a memory 132, an input device 134, and a display 135. The processing circuit 150 includes a B-mode processing function 150a, a Doppler processing function 150b, a generation function 150c, a display control function 150d, a reception function 150e, a control function 150f, a reconstruction function 150g, a design function 150h, a first analysis function 150i, and a second analysis function 150j.

[0024] In the embodiment, each processing function performed by the B-mode processing function 150a, the Doppler processing function 150b, the generation function 150c, the display control function 150d, the reception function 150e, the control function 150f, the reconstruction function 150g, the design function 150h, the first analysis function 150i, and the second analysis function 150j is stored in the memory 132 in the form of a program executable by a computer. The processing circuit 150 is a processor that reads out a program from the memory 132 and executes it to realize a function corresponding to each program. In other words, the processing circuit 150 in a state in which each program has been read out has each function shown in the processing circuit 150 in FIG. 1. Note that, in FIG. 1, the processing circuit 150 is described as being realized by a single processing circuit, but the processing circuit 150 may be configured by combining multiple independent processors, and each processor may execute a program to realize a function. In other words, each of the above-mentioned functions may be configured as a program, and one processing circuit may execute each program. Also, two or more of the functions of the processing circuit 150 may be realized by a single processing circuit. As another example, a specific function may be implemented in a dedicated independent program execution circuit.

[0025] 1, the processing circuitry 150, the B-mode processing function 150a, the Doppler processing function 150b, the generating function 150c, the display control function 150d, the receiving function 150e, the control function 150f, the reconstruction function 150g, the design function 150h, the first analysis function 150i, and the second analysis function 150j are examples of the B-mode processing unit, the Doppler processing unit, the generating unit, the display control unit, the receiving unit, the control unit, the reconstruction unit, the design unit, the first analysis unit, and the second analysis unit, respectively. Also, the transmitting circuitry 9 and the receiving circuitry 11 are examples of the transmitting and receiving unit.

[0026] The term “processor” used in the above description refers to a circuit such as a CPU (Central Processing Unit), a GPU (Graphical Processing Unit), an Application Specific Integrated Circuit (ASIC), a programmable logic device (e.g., a Simple Programmable Logic Device (SPLD), a Complex Programmable Logic Device (CPLD), and a Field Programmable Gate Array (FPGA)). The processor realizes functions by reading and executing a program stored in memory 132.

[0027] Also, instead of storing the program in the memory 132, the program may be directly built into the circuit of the processor. In this case, the processor realizes the function by reading and executing the program built into the circuit. The transmission circuit 9, reception circuit 11, etc. built into the ultrasound diagnostic device 10 may be configured as hardware such as an integrated circuit, but may also be a modularized program in software.

[0028] The processing circuitry 150 is a processing unit that performs various signal processing on the reception signal received from the reception circuitry 11. The processing circuitry 150 has a B-mode processing function 150a, a Doppler processing function 150b, a generation function 150c, a display control function 150d, a reception function 150e, a control function 150f, a reconstruction function 150g, a design function 150h, a first analysis function 150i, and a second analysis function 150j.

[0029] The processing circuit 150 receives data from the receiving circuit 11 using the B-mode processing function 150a, and performs logarithmic amplification processing, envelope detection processing, logarithmic compression processing, etc. to generate data (B-mode data) in which the signal intensity is expressed as brightness (luminance).

[0030] In addition, the processing circuit 150 uses the Doppler processing function 150b to perform frequency analysis of velocity information from the received signal (reflected wave data) received from the receiving circuit 11, and generates data (Doppler data) extracted from multiple points of moving object information such as velocity, dispersion, power, etc. due to the Doppler effect.

[0031] It should be noted that the B-mode processing function 150a and the Doppler processing function 150b illustrated in FIG. 1 are capable of processing both two-dimensional reflected wave data and three-dimensional reflected wave data.

[0032] The processing circuitry 150 controls the display 135 to display the ultrasound image data for display stored in the memory 132 using a display control function 150d.

[0033] The processing circuit 150 receives various operations from the user via the input device 134 using a reception function 150e.

[0034] The processing circuitry 150 controls the overall processing of the ultrasonic diagnostic apparatus by the control function 150f. Specifically, the processing circuitry 150 controls the processing of the transmission circuitry 9, the reception circuitry 11, and the processing circuitry 150 based on various setting requests input by the operator via the input device 134 and various control programs and various data read from the memory 132 by the control function 150f.

[0035] The processing circuit 150 generates ultrasound image data from the data generated by the B-mode processing function 150a and the Doppler processing function 150b using the generation function 150c. The processing circuit 150 generates two-dimensional B-mode image data, which expresses the intensity of the reflected wave as brightness, from the two-dimensional B-mode data generated by the B-mode processing function 150a using the generation function 150c. The processing circuit 150 also generates two-dimensional Doppler image data representing moving object information from the two-dimensional Doppler data generated by the Doppler processing function 150b using the generation function 150c. The two-dimensional Doppler image data is velocity image data, variance image data, power image data, or image data that is a combination of these.

[0036] Moreover, the processing circuit 150 converts (scan converts) the scan line signal sequence of the ultrasonic scan into a scan line signal sequence of a video format represented by a television or the like, using the generation function 150c, and generates ultrasonic image data for display. Furthermore, the processing circuit 150 performs various image processing other than scan conversion, such as image processing (smoothing processing) for regenerating an average brightness image using multiple image frames after scan conversion, and image processing (edge ​​enhancement processing) using a differential filter within an image, using the generation function 150c. Furthermore, the processing circuit 150 performs various rendering processing on the volume data to generate two-dimensional image data for displaying the volume data on the display 135, using the generation function 150c.

[0037] The processing circuit 150 also has a reconstruction function 150g, a design function 150h, a first analysis function 150i, and a second analysis function 150j. These functions will be described later.

[0038] The memory 132 is composed of a semiconductor memory element such as a RAM (Random Access Memory), a flash memory, a hard disk, an optical disk, etc. The memory 132 is a memory that stores data such as image data for display generated by the processing circuit 150. The memory 132 can also store data generated by the B-mode processing function 150a and the Doppler processing function 150b. The B-mode data and Doppler data stored in the memory 132 can be called up by an operator after diagnosis, for example, and become ultrasonic image data for display via the processing circuit 150. The memory 132 can also store a reception signal (reflected wave data) output by the receiving circuit 11.

[0039] In addition, the memory 132 stores, as necessary, control programs for performing ultrasound transmission and reception, image processing, and display processing, as well as various data such as diagnostic information (e.g., patient ID, doctor's findings, etc.), diagnostic protocols, and various body marks.

[0040] The input device 134 receives various instructions and information input from an operator. The input device 134 is, for example, a pointing device such as a mouse or a trackball, a selection device such as a mode changeover switch, or an input device such as a keyboard.

[0041] The display 135 displays a GUI (Graphical User Interface) for receiving input of imaging conditions and images generated by the generation function 150c under the control of the control function 150f, etc. The display 135 is, for example, a display device such as a liquid crystal display. The display 135 is an example of a display unit. The display 135 has a mouse, a keyboard, a button, a panel switch, a touch command screen, a foot switch, a trackball, a joystick, etc.

[0042] Next, the background of the embodiment will be described.

[0043] Seismic interferometry (also known as SPM (Shot-Profile Migration) or wavefield correlation method) is known in the field of seismic wave measurement. Seismic interferometry is a method for reconstructing the location of an underground earthquake and reflection surfaces, and estimates the location of the earthquake source by performing correlation processing between a forward propagation simulation of a transmitted wave field and a reverse propagation simulation of a received wave field.

[0044] Here, since seismic waves and ultrasound waves have in common the fact that they are elastic waves, it is conceivable that seismic interferometry could be used for image reconstruction in an ultrasound diagnostic apparatus to reconstruct an ultrasound image.

[0045] In ultrasound diagnostic equipment, a technique called harmonic imaging, which extracts and visualizes harmonic components in echoes, is widely used. Harmonic imaging is an important technique because it enables the suppression of echo components from undesired directions. Therefore, when applying seismic interferometry to image reconstruction in ultrasound diagnostic equipment, it is desirable to be able to perform harmonic imaging.

[0046] However, when simply applying seismic interferometry or SPM to image reconstruction in an ultrasound diagnostic device, the harmonic components generated during the ultrasound propagation process are not taken into account, so it is not possible to extract and visualize the harmonic components in the echo, and some ingenuity is required. Non-Patent Document 1 proposes an ultrasound image reconstruction method that applies seismic interferometry. However, the transmission sound field is forward-propagated based on the transmission signal from the piezoelectric transducer, which means that the harmonic components generated during the transmission signal's propagation through the living body are not taken into account.

[0047] The ultrasound diagnostic apparatus according to the embodiment is based on such a background, and includes a transmitting / receiving unit and a processing circuit 150. The transmitting / receiving unit transmits ultrasound to a subject under a first transmission condition and receives an echo from the subject. The processing circuit 150 creates a second transmission condition corresponding to the transmission of ultrasound with harmonic components added to the ultrasound based on the first transmission condition using a design function 150f. The processing circuit 150 forward-propagates the ultrasound transmitted based on the second transmission condition to obtain a transmission wave field using a first analysis function 150i. The processing circuit 150 back-propagates a signal based on the echo to obtain a reception wave field using a second analysis function 150j. The processing circuit 150 performs correlation analysis between the transmission wave field and the reception wave field using a reconstruction function 150g to generate a harmonic echo component.

[0048] In addition, the ultrasound diagnostic method according to the embodiment transmits ultrasound to a subject under a first transmission condition, receives an echo from the subject, creates a second transmission condition based on the first transmission condition that corresponds to transmitting ultrasound with harmonic components added to the ultrasound, forward propagates the ultrasound transmitted based on the second transmission condition to obtain a transmitted wave field, back propagates a signal based on the echo to obtain a received wave field, and performs correlation analysis between the transmitted wave field and the received wave field to generate harmonic echo components.

[0049] In this way, seismic interferometry can be applied to harmonic imaging in an ultrasound diagnostic device, making it possible to reconstruct ultrasound images while maintaining a high level of suppression capability for echo components from undesired directions, equivalent to or better than that of beamforming technology, for example.

[0050] The process performed by the ultrasound diagnostic apparatus 10 according to the first embodiment will be described with reference to FIGS.

[0051] First, an embodiment in which seismic interferometry is simply applied to ultrasonic diagnosis will be described with reference to Fig. 2 and Fig. 3. Fig. 2 is a schematic diagram illustrating the process in which seismic interferometry is simply applied to an ultrasonic diagnostic layer. Fig. 3 is a flowchart illustrating the process performed by the ultrasonic diagnostic device 10 in which seismic interferometry is simply applied to an ultrasonic diagnostic layer. The flowchart in Fig. 2 differs from the flowchart in Fig. 4, which is a process for performing harmonic imaging, in that the process of step S200 described later is not performed, and step S300X is performed in Fig. 2 instead of step S300 in Fig. 4.

[0052] First, in step S100, the transmission circuit 9 and the reception circuit 11 as a transmission / reception unit transmit ultrasonic waves to the subject under a first transmission condition and receive echoes from the subject. Typically, the ultrasonic diagnostic device 10 transmits ultrasonic waves multiple times in different directions by the transmission circuit 9, and the reception circuit 11 receives echoes from the subject for each of the multiple ultrasonic waves. For example, as shown in FIG. 2, the transmission circuit 9 transmits multiple ultrasonic waves 20a, 20b, and 20c. The reception circuit 11 receives echoes 40a, 40b, and 40c from the subject for each of the multiple ultrasonic waves 20a, 20b, and 20c, and acquires reception signals r1(x, t), r2(x, t), and r3(x, t) as reception signals 50, where x is the position coordinate in the direction of propagation of the ultrasonic beam and t is the time.

[0053] Here, the first transmission condition typically refers to a transmission condition such as the amplitude, phase, frequency, transmission aperture, or transmission apodization of the ultrasonic wave to be transmitted. Here, the transmission circuit 9 transmits ultrasonic wave 20a under transmission condition #1, ultrasonic wave 20b under transmission condition #2, and ultrasonic wave 20c under transmission condition #3, for example. Here, these transmission conditions #1, #2, and #3 are considered as one transmission condition and are treated as the first transmission condition 20.

[0054] Next, in step S300X, the processing circuit 150 calculates the transmission wave field 30 by forward propagating the ultrasonic waves transmitted based on the first transmission condition by forward propagation simulation using the first analysis function 150i. As an example, the processing circuit 150 calculates the transmission wave fields f1(x,y,t), f2(x,y,t) and f3(x,y,t) by forward propagation simulation using the first analysis function 150i to forward propagate the ultrasonic waves 20a, 20b and 20c transmitted under the transmission condition #1, the transmission condition #2 and the transmission condition #3. Here, x represents the position coordinate in the direction perpendicular to the propagation direction of the ultrasonic beam, y represents the position coordinate in the propagation direction of the ultrasonic beam, and t represents the time. The processing circuit 150 calculates the transmission wave field 30 based on the first transmission condition by simulating the time evolution of the wave equation using the first analysis function 150i. As one example, the processing circuit 150 uses the first analysis function 150i to calculate the transmission wave field 30 based on the first transmission condition, for example, by using the finite difference time domain method (FDTD). As another example, the processing circuit 150 uses the first analysis function 150i to calculate the transmission wave field 30 based on the first transmission condition, for example, by using a simulation method using the angular spectrum method.

[0055] Next, in step S400, the processing circuit 150 uses the second analysis function 150j to back-propagate the received signal 50 based on the echo acquired in step S100 to calculate the received wave field 60. As an example, the processing circuit 150 uses the second analysis function 150j to simulate the time evolution of a wave equation using, for example, the FDTD method to calculate the received wave fields b1(x,y,t), b2(x,y,t), and b3(x,y,t) from the received signals r1(x), r2(x), and r3(x), respectively.

[0056] Next, in step S500, the processing circuit 150 performs correlation analysis between the transmitted wave field and the received wave field using the reconstruction function 150g to generate an image. Specifically, an image I is generated by the following equation (1).

[0057]

number

[0058] Here, n is an index that distinguishes each ultrasonic wave 20a, 20b, 20c, etc., and N represents the number of ultrasonic transmissions included in the series of ultrasonic transmissions. Also, "*" represents a complex conjugate.

[0059] As described above, the processing circuit 150 generates the image I by using the SPM method. However, when harmonic imaging is performed, the first transmission condition under which the transmission circuit 9 transmits ultrasonic waves is a transmission condition that does not usually include high-order harmonic components, so the transmission wave field 30 obtained by the forward propagation simulation also does not include high-order harmonic components. As a result, even if a correlation analysis is performed between the transmission wave field 30 and the reception wave field 60 in step S500, high-order harmonic components are not sufficiently extracted in the image I. That is, the transmission ultrasonic waves are matched filtered by the transmission band, so that the band of the transmission ultrasonic waves is band-limited and the signal of the high-order harmonic components is suppressed.

[0060] Therefore, the ultrasonic diagnostic device 10 according to the embodiment creates a second transmission condition corresponding to the transmission of ultrasonic waves to which harmonic components have been added based on the first transmission condition, and generates an image based on this. As an example, the processing circuit 150 creates a second transmission condition by adding a pulse signal of a wide band that covers the propagating harmonic components or the band of the propagating harmonic components itself to the first transmission condition using the design function 150h, and generates an image based on this. This makes it possible to extract high-order harmonic components.

[0061] These points will be described with reference to Figures 4 and 5. Figure 4 is a diagram illustrating the processing performed by the ultrasound diagnostic device 10 according to the first embodiment. Also, Figure 5 is a flowchart illustrating the flow of processing performed by the ultrasound diagnostic device 10 according to the first embodiment.

[0062] First, in step S100, similarly to Fig. 2, the transmission circuitry 9 and the reception circuitry 11 as a transmission / reception unit transmit ultrasonic waves to a subject under a first transmission condition and receive echoes from the subject. In the ultrasonic diagnostic device 10, the transmission circuitry 9 transmits ultrasonic waves multiple times in different directions, for example, and the reception circuitry 11 receives echoes from the subject for each of the multiple ultrasonic waves. For example, as shown in Fig. 4, the transmission circuitry 9 transmits multiple phase-modulated ultrasonic waves 20a, 20b, and 20c in the same direction.

[0063] In addition, the receiving circuit 11 receives echoes 40a, 40b, 40c from the subject for each of the multiple ultrasonic waves 20a, 20b, 20c, and acquires receiving signals r1(x,t), r2(x,t), and r3(x,t) as receiving signals 50, where x is the position coordinate in the direction of propagation of the ultrasonic beam and t is the time.

[0064] Here, the first transmission condition typically refers to a transmission condition such as the amplitude, phase, frequency, transmission aperture, or transmission apodization of the ultrasonic wave to be transmitted. Here, the transmission circuit 9 transmits ultrasonic wave 20a under transmission condition #1, ultrasonic wave 20b under transmission condition #2, and ultrasonic wave 20c under transmission condition #3, for example. These transmission conditions #1, #2, and #3 are considered as one transmission condition and are treated as the first transmission condition 20.

[0065] Next, in step S200, the processing circuit 150 uses the design function 150h to create a second transmission condition corresponding to the transmission of ultrasonic waves in which harmonic components are added to the ultrasonic waves based on the first transmission condition. Here, such harmonic components are artificially added to the first transmission condition under which ultrasonic waves are actually transmitted in order to extract high-order harmonic components contained in the received wave field when performing correlation analysis between the transmitted wave field and the received wave field in the processing of step S500. In this way, the processing circuit 150 uses the design function 150h to artificially add harmonic components 80 to the first transmission condition 20 under which ultrasonic waves were actually transmitted to generate the second transmission condition 90, so that high-order harmonic components can be extracted when performing correlation analysis between the transmitted wave field and the received wave field.

[0066] Here, as a first mode in which the processing circuit 150 adds the harmonic components to the first transmission condition by using the design function 150h, for example, a transmission condition of a wideband signal that widely covers the propagating harmonic components is added to the first transmission condition 20 to generate the second transmission condition 90. Also, as a second mode in which the processing circuit 150 adds the harmonic components to the first transmission condition by using the design function 150h, for example, a pulse signal that has a large signal strength only in the band of the propagating harmonic components is added to the first transmission condition 20 to generate the second transmission condition 90. As an example, the processing circuit 150 uses the design function 150h to create a transmission condition that has a frequency band of harmonic components compared to the first transmission condition and is the same as the first transmission condition except for the frequency band, as the second transmission condition. That is, the processing circuit 150 uses the design function 150h to generate a second transmission condition that has a different frequency compared to the first transmission condition.

[0067] Note that the embodiment is not limited to this, and the processing circuit 150 may generate a second transmission condition that is different from the first transmission condition in at least one of the conditions of, for example, amplitude, phase, transmission aperture, and transmission apodization, by using the design function 150h. As an example, the processing circuit 150 may generate a second transmission condition that transmits an ultrasonic wave with a narrower beam than the ultrasonic wave transmitted under the first transmission condition by changing the transmission aperture or transmission apodization with respect to the first transmission condition by using the design function 150h, for example, so as to reduce the influence of side lobes.

[0068] In addition, the processing circuit 150 may use the design function 150h to change conditions other than frequency, such as amplitude, phase, transmission aperture, and transmission apodization, from the first transmission condition to generate the second transmission condition, which is also applicable to the second and subsequent embodiments and modified examples of the embodiments.

[0069] Next, in step S300, the processing circuit 150 calculates the transmission wave field 30 by forward propagating the ultrasonic waves transmitted based on the second transmission condition by forward propagation simulation using the first analysis function 150i. As an example, the processing circuit 150 calculates the transmission wave fields f1(x,y,t), f2(x,y,t) and f3(x,y,t) by forward propagation simulation using the first analysis function 150i when the ultrasonic waves are transmitted under the second transmission condition 90 to which the harmonic component 80 is added for the transmission condition #1, the transmission condition #2 and the transmission condition #3. Here, x represents the position coordinate in the direction perpendicular to the propagation direction of the ultrasonic beam, y represents the position coordinate in the propagation direction of the ultrasonic beam, and t represents the time. The processing circuit 150 calculates the transmission wave field 30 based on the second transmission condition by simulating the time evolution of the wave equation using the first analysis function 150i. As one example, the processing circuit 150 uses the first analysis function 150i to calculate the transmission wave field 30 based on the second transmission condition, for example, by using the FDTD method. As another example, the processing circuit 150 uses the first analysis function 150i to calculate the transmission wave field 30 based on the second transmission condition, for example, by using a simulation method using the angular spectrum method.

[0070] Next, in step S400, the processing circuit 150 uses the second analysis function 150j to back-propagate the received signal 50 based on the echo acquired in step S100 to calculate the received wave field 60. As an example, the processing circuit 150 uses the second analysis function 150j to simulate the time evolution of a wave equation using, for example, the FDTD method to calculate the received wave fields b1(x,y,t), b2(x,y,t), and b3(x,y,t) from the received signals r1(x), r2(x), and r3(x), respectively. As another example, the processing circuit 150 uses the second analysis function 150j to back-propagate the received signal 50 to calculate the received wave field 60 using a simulation method using the angular spectrum method.

[0071] Next, in step S500, the processing circuit 150 performs correlation analysis between the transmitted wave field and the received wave field using the reconstruction function 150g to generate harmonic echo components. Specifically, the processing circuit 150 generates an image I including harmonic echo components using the reconstruction function 150g according to the above-mentioned formula (1).

[0072] As described above, in the first embodiment, the processing circuit 150 creates the second transmission condition in which the harmonic components are added to the ultrasonic wave based on the first transmission condition by the design function 150h, and performs correlation analysis based on this. This makes it possible to extract the harmonic components, improving image quality.

[0073] Second embodiment In the first embodiment, a general embodiment has been described in which the transmitting and receiving unit transmits one or a plurality of ultrasonic waves to the subject under a first transmission condition in step S100. In the second embodiment, a case in which the transmitting and receiving unit transmits a plurality of ultrasonic waves using a so-called Pulse Inversion method will be described in more detail with reference to Figs. 6 to 8.

[0074] FIG. 6 is a flow chart for explaining the flow of processing performed by the ultrasonic diagnostic device 10 according to the second embodiment. First, in step S100A, the transmission circuit 9 and the reception circuit 11 as a transmitting / receiving unit transmit ultrasonic waves to a subject under a first transmission condition and receive an echo from the subject. In the ultrasonic diagnostic device 10, the transmission circuit 9 transmits phase-modulated ultrasonic waves in the same direction multiple times, and the reception circuit 11 receives an echo from the subject for each of the multiple ultrasonic waves. That is, the transmission circuit 9 transmits multiple ultrasonic waves in multiple first transmissions, and the reception circuit 11 receives multiple echoes. For example, when one set of ultrasonic transmission is performed by two transmissions, as shown in FIG. 7, the transmission circuit 9 transmits ultrasonic waves 20a under a first first transmission condition 21a that transmits ultrasonic waves at a transmission phase of 0 degrees, which is a first transmission phase, and receives a first echo, and transmits ultrasonic waves 20b under a second first transmission condition 21b that transmits ultrasonic waves at a second transmission phase that is a transmission phase 180 degrees different from the first transmission phase, and receives a second echo.

[0075] In addition, the embodiment is not limited to the case where one set of ultrasonic transmission is performed by two transmissions, and may be the case where one set of ultrasonic transmission is performed by three transmissions, for example. In this case, as shown in Fig. 8, the transmission circuit 9 transmits ultrasonic wave 20a and receives a first echo under a first first transmission condition 21a in which ultrasonic wave is transmitted at a transmission phase of 0 degrees, which is a first transmission phase, transmits ultrasonic wave 20b and receives a second echo under a second first transmission condition 21b in which ultrasonic wave is transmitted at a second transmission phase, which is a transmission phase different from the first transmission phase by 120 degrees, and transmits ultrasonic wave 20c and receives a third echo under a third first transmission condition 21c in which ultrasonic wave is transmitted at a third transmission phase, which is a transmission phase different from the first transmission phase by 240 degrees.

[0076] 6, in step S200A, the processing circuit 150 uses the design function 150h to create second transmission conditions corresponding to the transmission of ultrasonic waves to which harmonic components have been added, based on the first transmission conditions. That is, the processing circuit 150 uses the setting function 150h to create multiple second transmission conditions for each of the multiple first transmission conditions.

[0077] Specifically, in the case where one set of ultrasonic transmissions is performed by two transmissions as shown in FIG. 7, the processing circuit 150 uses the design function 150h to create a first second transmission condition 90a based on the first first transmission condition 21a by adding a harmonic component 80 to the first first transmission condition 21a, and creates a second second transmission condition 90b based on the second first transmission condition 21b by adding a harmonic component 80 to the second first transmission condition 21b. Furthermore, in the case where one set of ultrasonic transmissions is performed with three transmissions as shown in FIG. 8, the processing circuit 150, by the design function 150h, creates a first second transmission condition 90a based on the first first transmission condition 21a by adding a harmonic component 80 to the first first transmission condition 21a, creates a second second transmission condition 90b based on the second first transmission condition 21b by adding a harmonic component 80 to the second first transmission condition 21b, and creates a third second transmission condition 90c based on the third first transmission condition 21c by adding a harmonic component 80 to the third first transmission condition 21c.

[0078] Here, as a first mode in which the processing circuit 150 adds the harmonic components to the first transmission condition by using the design function 150h, for example, a transmission condition of a wideband signal that widely covers the propagating harmonic components is added to the first transmission condition 20 to generate the second transmission condition 90. Also, here, as a second mode in which the processing circuit 150 adds the harmonic components to the first transmission condition by using the design function 150h, for example, a pulse signal that has a large signal strength only in the band of the propagating harmonic components is added to the first transmission condition 20 to generate the second transmission condition 90. As an example, the processing circuit 150 creates, as the second transmission condition, a transmission condition that has a frequency band of the harmonic components compared to the first transmission condition and is the same as the first transmission condition except for the frequency band, by using the design function 150h. The processing circuit 150 performs the above-mentioned process for each of the multiple first transmission conditions to create multiple second transmission conditions. The processing circuit 150 generates, by the design function 150h, a second transmission condition that is different from the first transmission condition in at least one of the conditions of the amplitude, phase, frequency, transmission aperture, and transmission apodization.

[0079] In step S300A, the processing circuit 150 calculates the transmission wave field 30 by forward propagating the ultrasonic wave transmitted based on the second transmission condition by forward propagation simulation using the first analysis function 150i. That is, the processing circuit 150 obtains a transmission wave field for each of the multiple second transmission conditions using the first analysis function 150i. For example, the processing circuit 150 performs a forward propagation simulation based on the first second transmission condition using the first analysis function 150i to obtain a first transmission wave field, and performs a forward propagation simulation based on the second second transmission condition to obtain a second transmission wave field. The processing circuit 150 calculates the transmission wave field 30 based on the second transmission condition 90 using the first analysis function 150i, for example, by simulating the time evolution of a wave equation, for example, by using a simulation method using the FDTD method or the angular spectrum method.

[0080] Next, in step S400A, the processing circuit 150 uses the second analysis function 150j to back-propagate the received signal 50 based on the echo acquired in step S100 to calculate the received wave field 60. That is, the processing circuit 150 uses the second analysis function 150j to perform a back-propagation simulation on the echo corresponding to each of the multiple first transmission conditions to obtain the received wave field 60. Specifically, the processing circuit 150 uses the second analysis function 150j to obtain a first received wave field based on the first echo corresponding to the first first transmission condition, and obtains a second received wave field based on the second echo corresponding to the second first transmission condition. For example, the processing circuit 150 uses the second analysis function 150j to back-propagate the echo corresponding to the transmission condition to obtain these received wave fields by simulating the time evolution of the wave equation using, for example, the FDTD method, or by using a simulation method using the angular spectrum method.

[0081] Next, in step S500A, the processing circuit 150 performs a correlation analysis by using the reconstruction function 150g to evaluate, for example, the right side of formula (1) between the transmitted wave field and the received wave field for each of the first transmission conditions and the corresponding second transmission conditions. The processing circuit 150 performs a correlation analysis by using the reconstruction function 150g between the first transmitted wave field and the first received wave field based on formula (1) to generate a first signal distribution, and performs a correlation analysis between the second transmitted wave field and the second received wave field based on formula (1) to generate a second signal distribution.

[0082] Next, in step S550A, the processing circuit 150 generates harmonic echo components based on the result of the correlation analysis by the reconstruction function 150g. For example, the processing circuit 150 generates harmonic echo components based on the first signal distribution and the second signal distribution by the reconstruction function 150g. Here, since the transmission phase of the transmitted ultrasonic wave for the second signal distribution is shifted by 180 degrees from the transmission phase of the transmitted ultrasonic wave corresponding to the first signal distribution, the processing circuit 150 generates harmonic echo components by performing subtraction processing between the first signal distribution and the second signal distribution by the reconstruction function 150g. Note that, in the normal pulse inversion method, the harmonic echo components are extracted by adding the signal distributions related to each ultrasonic transmission. In a normal pulse inversion method, the harmonic components in the received signal obtained under the first transmission condition and the second transmission condition are in phase, but in this example, the transmitted wave field with a transmission phase difference of 180 degrees is correlated with the received wave field, so that the harmonic components in the received signal are rotated 180 degrees and are in the opposite phase between the first and second transmission conditions. Therefore, in order to extract the harmonic components, a subtraction process is applied between the first signal distribution and the second signal distribution. Note that the embodiment is not limited to the subtraction process, and for example, the transmission phase is made in phase between the first and second transmission conditions and the first and second transmission conditions, that is, if a transmission condition that is different not only in frequency but also in phase from the transmission condition given to the transmission circuit 9 is artificially created as the first and second transmission conditions and the second transmission conditions, the harmonic echo components can be extracted by an addition process between the first signal distribution and the second signal distribution.

[0083] As described above, in the second embodiment, when a plurality of ultrasonic waves are transmitted, correlation analysis is performed for each transmitted ultrasonic wave, and harmonic components are extracted based on the obtained signal distributions. This makes it possible to perform harmonic imaging that extracts harmonic components, thereby improving image quality.

[0084] (Modification of the second embodiment) In the second embodiment, a case where a plurality of ultrasonic waves are transmitted, correlation analysis is performed for each transmitted ultrasonic wave, and harmonic components are extracted based on the obtained plurality of signal distributions. In the modified example of the second embodiment, a case where correlation analysis is performed by treating a plurality of ultrasonic transmissions as one transmission condition will be described.

[0085] FIG. 9 is a flowchart illustrating the flow of processing performed by the ultrasound diagnostic apparatus 10 according to a modified example of the second embodiment.

[0086] First, in step S100B, the transmission circuitry 9 and the reception circuitry 11 as a transmission / reception unit transmit ultrasonic waves to the subject under a first transmission condition and receive echoes from the subject. In the ultrasonic diagnostic device 10, the transmission circuitry 9 transmits multiple phase-modulated ultrasonic waves in the same direction under multiple transmission conditions, and the reception circuitry 11 receives echoes from the subject for each of the multiple ultrasonic waves. Specifically, the transmission circuitry 9 transmits multiple ultrasonic waves under multiple transmission conditions, and the reception circuitry 11 receives multiple echoes corresponding to the multiple ultrasonic waves.

[0087] 10, the transmission circuit 9 transmits, for example, an ultrasonic wave 20a at a first transmission phase of 0 degrees, and transmits an ultrasonic wave 20b at a second transmission phase of 180 degrees. In the modified example of the second embodiment, the process in which the transmission circuit 9 transmits the ultrasonic waves 20a and 20b under their respective transmission conditions and the reception circuit 11 receives a plurality of echoes is treated as the transmission and reception unit transmitting one ultrasonic wave under one first transmission condition 21.

[0088] Next, in step S200B, the processing circuit 150 creates a second transmission condition corresponding to the transmission of ultrasonic waves to which harmonic components have been added based on the first transmission condition by using the design function 150h. Specifically, the processing circuit 150 creates a second transmission condition 90 by adding harmonic components 80 to the first transmission condition 21 while treating the process in which the transmitting and receiving unit transmits ultrasonic waves multiple times under multiple transmission conditions and receives multiple echoes as if the transmitting and receiving unit transmits one ultrasonic wave under one first transmission condition by using the design function 150h.

[0089] Next, in step S300B, the processing circuit 150 uses the first analysis function 150i to perform forward propagation simulation to forward propagate the ultrasonic waves transmitted based on the second transmission condition to obtain the transmission wave field 30. The processing circuit 150 uses the first analysis function 150i to calculate the transmission wave field 30 based on the second transmission condition 90, for example, by simulating the time evolution of a wave equation, for example, by using a simulation method using the FDTD method or the angular spectrum method.

[0090] On the other hand, in step S350B, the processing circuit 150 uses the second analysis function 150j to synthesize the multiple echoes received in step S100B to extract a reception signal including a harmonic component. As an example, when the transmission circuit 9 transmits ultrasonic waves as a set of two ultrasonic transmissions with a transmission phase difference of 180 degrees, the processing circuit 150 uses the second analysis function 150j to simply add up the multiple echoes received in step S100B to extract a reception signal including a second harmonic component. As another example, when the transmission circuit 9 transmits ultrasonic waves as a set of three ultrasonic transmissions with a transmission phase difference of 120 degrees, the processing circuit 150 uses the second analysis function 150j to simply add up the multiple echoes received in step S100B to extract a reception signal including a third harmonic component.

[0091] Next, in step S400B, the processing circuit 150 uses the second analysis function 150j to back-propagate the reception signal 50 based on the echo acquired in step S100 to calculate the reception wave field 60. That is, the processing circuit 150 uses the second analysis function 150j to back-propagate the reception signal 50 extracted in step S350B based on the echo acquired in step S100 to obtain the reception wave field 60. For example, the processing circuit 150 uses the second analysis function 150j to back-propagate the echo corresponding to the transmission condition to obtain the reception wave field 60 by simulating the time evolution of the wave equation using, for example, the FDTD method or by using a simulation method using the angular spectrum method.

[0092] Next, in step S500B, the processing circuit 150 performs correlation analysis by the reconstruction function 150g between the transmission wave field 30 calculated in step S300B and the reception wave field 60 calculated in step S400B to generate harmonic echo components. As an example, the processing circuit 150 performs correlation analysis by the reconstruction function 150g between the transmission wave field 30 and the reception wave field 60 by evaluating, for example, the right side of equation (1) to obtain an image I. Since the obtained image I contains harmonic echo components, the processing circuit 150 can extract the harmonic components by performing correlation analysis by the reconstruction function 150g.

[0093] As described above, in the modified example of the second embodiment, when transmitting multiple ultrasonic waves, the multiple ultrasonic waves are first synthesized, and then correlation analysis is performed to extract harmonic components. This makes it possible to perform harmonic imaging that extracts harmonic components, thereby improving image quality.

[0094] (Third embodiment) The embodiments are not limited to the above examples. In the first embodiment, a case has been described in which a simulation of forward propagation or backward propagation of a transmission wave field or a reception wave field is performed in step S300 or step S400 without taking into consideration the nonlinear effect of the medium. However, the embodiments are not limited to this. In the third embodiment, a case will be described in which a simulation is performed that also takes into account the nonlinear effect of the medium.

[0095] 11 is a flowchart illustrating the flow of processing performed by the ultrasound diagnostic apparatus 10 according to the third embodiment. Here, the processing other than step S300C is similar to the processing described in FIG. 5 in the first embodiment, and therefore repeated description of these processing will be omitted.

[0096] In step S300C, the processing circuit 150 uses the first analysis function 150c to forward propagate the ultrasonic waves transmitted based on the second transmission condition using a simulation method that takes into account the nonlinear components of the medium to calculate the transmission wave field 30. As an example, the processing circuit 150 uses the first analysis function 150c to forward propagate the ultrasonic waves transmitted based on the second transmission condition using a simulation method that uses the finite element method, for example, to calculate the transmission wave field 30. By performing a simulation that takes into account the nonlinear effects of the medium, further improvement in image quality can be expected.

[0097] Similarly, in step S400, the processing circuitry 150 may obtain the received wave field 60 by backpropagating the echo-based signal using a simulation method that takes into account the nonlinear components of the medium, using the second analysis function 150j.

[0098] Note that the processing circuitry 150 may measure the nonlinear parameters of the medium in advance before performing the processing of step S100 using the design function 150h, and store the measured nonlinear parameters of the medium in the memory 132. Thereafter, in step S300C or step S400, the processing circuitry 150 may call up the stored nonlinear parameters of the medium from the memory 132 and use them in the simulation.

[0099] As another example, the processing circuit 150 may receive values ​​of the nonlinear parameters of the medium from a user using a user interface through the reception function 150e, and store the received nonlinear parameters of the medium in the memory 132. Then, in step S300C or step S400, the processing circuit 150 may call up the stored nonlinear parameters of the medium from the memory 132 and use them in the simulation.

[0100] As described above, the ultrasonic diagnostic apparatus 10 according to the third embodiment can achieve further improvement in image quality by performing a simulation taking into account the nonlinear parameters of the medium.

[0101] According to at least one of the embodiments described above, image quality can be improved.

[0102] Although some embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations of embodiments can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents as described in the claims, as well as in the scope and spirit of the invention. [Explanation of symbols]

[0103] 5 Ultrasound probe 9 Transmitting circuit 11 Receiving circuit 132 Memory 134 Input Devices 135 Display 150 Processing circuit 150a B mode processing function 150b Doppler processing function 150c generation function 150d Display control function 150e Reception function 150f Control Function 150g reconfiguration function 150h design features 150i 1st analysis function 150j 2nd analysis function

Claims

1. a transceiver unit that transmits ultrasonic waves to a subject under a first transmission condition and receives echoes from the subject; a design unit that creates a second transmission condition corresponding to transmission of an ultrasonic wave in which a harmonic component is added to the ultrasonic wave, based on the first transmission condition; a first analysis unit that obtains a transmission wave field by forward propagating the ultrasonic waves transmitted based on the second transmission condition; a second analyzer for backpropagating the echo-based signal to obtain a received wave field; a reconstruction unit that performs correlation analysis between the transmitted wave field and the received wave field to generate harmonic echo components; An ultrasound diagnostic device comprising:

2. 2. The ultrasound diagnostic apparatus according to claim 1, wherein the design unit creates, as the second transmission condition, a transmission condition that has a frequency band of harmonic components compared to the first transmission condition, and is identical to the first transmission condition in all respects except for the frequency band, as the second transmission condition.

3. The ultrasound diagnostic device according to claim 1 , wherein the transmitting and receiving unit transmits phase-modulated ultrasound waves in the same direction a plurality of times, and receives an echo from the subject for each of the plurality of ultrasound waves.

4. The transmission / reception unit transmits ultrasonic waves a plurality of times under the plurality of first transmission conditions and receives a plurality of the echoes; the design unit creates a plurality of the second transmission conditions for each of the plurality of first transmission conditions; The first analysis unit obtains the transmission wave field for each of the plurality of second transmission conditions, The second analysis unit obtains the received wave field for the echo corresponding to each of the plurality of first transmission conditions, 2. The ultrasound diagnostic device according to claim 1, wherein the reconstruction unit performs a correlation analysis between the transmitted wave field and the received wave field for each of the first transmission conditions and the corresponding second transmission conditions, and generates the harmonic echo components based on a result of the correlation analysis.

5. the transmitting / receiving unit transmits the ultrasonic waves under the first transmission condition in a first transmission phase and receives a first echo, and transmits the ultrasonic waves under the second first transmission condition in a second transmission phase that is 180 degrees different from the first transmission phase and receives a second echo; the design unit creates a first second transmission condition based on the first first transmission condition, and creates a second second transmission condition based on the second first transmission condition; The first analyzer obtains a first transmission wave field based on the first second transmission condition, obtaining a second transmit wave field based on the second second transmit condition; The second analysis unit obtains a first received wave field based on the first echo and obtains a second received wave field based on the second echo; 5. The ultrasound diagnostic device according to claim 4, wherein the reconstruction unit performs a correlation analysis between the first transmitted wave field and the first received wave field to generate a first signal distribution, performs a correlation analysis between the second transmitted wave field and the second received wave field to generate a second signal distribution, and generates the harmonic echo component based on the first signal distribution and the second signal distribution.

6. The ultrasonic diagnostic apparatus according to claim 5 , wherein the reconstruction unit generates the harmonic echo component by performing a subtraction process between the first signal distribution and the second signal distribution.

7. The transmitting / receiving unit transmits ultrasonic waves a plurality of times under a plurality of transmission conditions and receives a plurality of the echoes; The design unit treats a process in which the transmission / reception unit transmits the ultrasonic waves a plurality of times under a plurality of transmission conditions and receives a plurality of the echoes as the transmission / reception unit transmitting one ultrasonic wave under one of the first transmission conditions, the design unit creates the second transmission condition based on the first transmission condition; The first analysis unit obtains the transmitted wave field based on the second transmission condition, The second analyzer obtains the received wave field based on the plurality of echoes, The ultrasonic diagnostic apparatus according to claim 1 , wherein the reconstruction unit performs the correlation analysis between the transmitted wave field and the received wave field to generate the harmonic echo component.

8. The second analyzer combines the echoes to extract a received signal including a harmonic component, The ultrasonic diagnostic apparatus according to claim 7 , wherein the received wave field is obtained based on the extracted received signal.

9. The ultrasonic diagnostic apparatus according to claim 1 , wherein the first analyzer obtains the transmission wave field by forward propagating the ultrasonic waves using a simulation method that takes into account a nonlinear component of a medium.

10. The ultrasonic diagnostic apparatus according to claim 1 , wherein the second analysis unit obtains the received wave field by backpropagating a signal based on the echo using a simulation method that takes into account a nonlinear component of a medium.

11. The ultrasonic diagnostic apparatus according to claim 1 , wherein at least one of the first analysis unit and the second analysis unit uses a simulation method using an angular spectrum analysis.

12. Transmitting ultrasonic waves to a subject under a first transmission condition and receiving echoes from the subject; creating a second transmission condition corresponding to transmission of an ultrasonic wave in which a harmonic component is added to the ultrasonic wave based on the first transmission condition; The ultrasonic waves transmitted based on the second transmission condition are forward propagated to obtain a transmission wave field; backpropagating the echo-based signals to obtain a received wave field; A method of ultrasound diagnosis, comprising performing a correlation analysis between the transmitted wave field and the received wave field to generate harmonic echo components.

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