JP6257892B2 - Ultrasonic diagnostic apparatus and control program - Google Patents

Description

  Embodiments described herein relate generally to an ultrasonic diagnostic apparatus and a control program.

  Conventionally, elastography is known as a technique for measuring the hardness of a living tissue and visualizing the distribution of the measured hardness. Elastography is used for diagnosis of diseases in which the hardness of a living tissue changes according to the degree of progression of a lesion, such as liver cirrhosis.

  In elastography, a living tissue is displaced by applying an acoustic radiation force or mechanical vibration to a subject. Here, as an example of the acoustic radiation force, there is a push pulse that is a focused ultrasonic pulse having a high sound pressure transmitted from an ultrasonic probe. Moreover, as an example of the mechanical vibration, it is mentioned to repeatedly press and release the living body surface. Then, the hardness of the living tissue is measured by observing the propagation velocity at which the displacement of the living tissue propagates with an ultrasonic pulse for observing the propagation velocity, and is visualized with a color corresponding to the hardness.

  Here, in order to observe the propagation speed of the mutation, transmission / reception of ultrasonic waves for propagation speed observation is performed a plurality of times on each of a plurality of scanning lines in the imaging region. That is, in order to observe the propagation speed for all the scanning lines in the imaging region, it is necessary to transmit and receive an ultrasonic wave a great number of times according to the number of scanning lines. For this reason, in elastography, the ultrasonic probe is likely to generate heat due to transmission and reception of ultrasonic waves.

JP 2010-069295 A JP 2012-125549 A JP 2012-115666 A International Publication No. 2011/064688 US Patent Application Publication No. 2004/0167403

  The problem to be solved by the present invention is to provide an ultrasonic diagnostic apparatus and a control program capable of suppressing heat generation of an ultrasonic probe when measuring the hardness of a living tissue.

The ultrasonic diagnostic apparatus according to the embodiment includes a transmission / reception unit and a control unit. Each time the living tissue is displaced by acoustic radiation force or mechanical vibration, the transmitting / receiving unit transmits and receives ultrasonic waves for measuring the displacement of the living tissue multiple times for each of the plurality of scanning lines in the scanning line region. Let it run. The control unit refers to information in which the upper limit and the lower limit of the estimated speed of propagation speed are associated with each diagnosis site or each disease type, and the expected speed corresponding to the specified diagnosis site or disease type An observation period is determined for each scanning line based on the upper limit and the lower limit, and transmission / reception of a plurality of times of ultrasonic waves executed on each scanning line by the transmission / reception unit is executed for the observation period.

FIG. 1 is a block diagram illustrating a configuration example of the ultrasonic diagnostic apparatus according to the first embodiment. FIG. 2 is a diagram illustrating an example of hardness image data generated by the image generation unit. FIG. 3 is a diagram (1) for explaining transmission and reception of push pulses and tracking pulses. FIG. 4 is a diagram (2) for explaining transmission and reception of push pulses and tracking pulses. FIG. 5A is a diagram (1) for explaining the process of acquiring the arrival time of the shear wave. FIG. 5B is a diagram (2) for explaining the process of acquiring the arrival time of the shear wave. FIG. 5C is a diagram (3) for explaining the process of acquiring the arrival time of the shear wave. FIG. 6 is a diagram for explaining processing for observing the propagation velocity of displacement. FIG. 7 is a diagram for explaining processing of the control unit according to the first embodiment. FIG. 8 is a flowchart for explaining an example of a processing procedure of the ultrasonic diagnostic apparatus according to the first embodiment. FIG. 9 is a diagram for explaining processing of the control unit according to the second embodiment. FIG. 10 is a diagram for explaining processing of the control unit according to the third embodiment.

  Hereinafter, an ultrasonic diagnostic apparatus and a control program according to embodiments will be described with reference to the drawings.

(First embodiment)
First, the configuration of the ultrasonic diagnostic apparatus according to the first embodiment will be described. FIG. 1 is a block diagram illustrating a configuration example of the ultrasonic diagnostic apparatus according to the first embodiment. The ultrasonic diagnostic apparatus according to the first embodiment is an apparatus capable of performing elastography. In elastography, an image (hardness image) that visualizes the hardness of a living tissue is generated and displayed. As shown in FIG. 1, the ultrasonic diagnostic apparatus according to the first embodiment includes an ultrasonic probe 1, a monitor 2, an input unit 3, and an apparatus main body 10.

  The ultrasonic probe 1 has a plurality of transducers, and the plurality of transducers transmit ultrasonic waves based on a drive signal supplied from a transmission / reception unit 11 included in the apparatus main body 10 to be described later. The vibrator included in the ultrasonic probe 1 is, for example, a piezoelectric vibrator. The ultrasonic probe 1 receives a reflected wave signal from the subject P and converts it into an electrical signal. The ultrasonic probe 1 includes a matching layer provided on the piezoelectric vibrator, a backing material that prevents propagation of ultrasonic waves from the piezoelectric vibrator to the rear, and the like. The ultrasonic probe 1 is detachably connected to the apparatus main body 10.

  When ultrasonic waves are transmitted from the ultrasonic probe 1 to the subject P, the transmitted ultrasonic waves are reflected one after another at the discontinuous surface of the acoustic impedance in the body tissue of the subject P, and the ultrasonic probe is used as a reflected wave signal. 1 is received by a plurality of piezoelectric vibrators. The amplitude of the received reflected wave signal depends on the difference in acoustic impedance at the discontinuous surface where the ultrasonic wave is reflected. Note that the reflected wave signal when the transmitted ultrasonic pulse is reflected by the moving blood flow or the surface of the heart wall depends on the velocity component of the moving object in the ultrasonic transmission direction due to the Doppler effect. And undergoes a frequency shift.

  The first embodiment can be applied regardless of whether the subject P is scanned two-dimensionally or three-dimensionally with the ultrasonic probe 1 shown in FIG.

  The monitor 2 displays a GUI (Graphical User Interface) for an operator of the ultrasonic diagnostic apparatus to input various setting requests using the input unit 3, and displays ultrasonic image data generated in the apparatus main body 10. It is a display device that displays.

  The input unit 3 receives input of various requests from the operator of the ultrasonic diagnostic apparatus, and transfers the received various requests to the apparatus main body 10. The input unit 3 is a mouse, a keyboard, a button, a panel switch, a touch command screen, a foot switch, a trackball, or the like. For example, the input unit 3 receives an input of a hardness image display request from an operator, and outputs the received hardness image display request to the control unit 16 described later.

  The apparatus main body 10 is an apparatus that generates ultrasonic image data based on a reflected wave signal received by the ultrasonic probe 1. As illustrated in FIG. 1, the apparatus main body 10 includes a transmission / reception unit 11, a signal processing unit 12, an image generation unit 13, an image memory 14, an internal storage unit 15, and a control unit 16.

  The transmission / reception unit 11 controls transmission / reception of ultrasonic waves performed by the ultrasonic probe 1 based on an instruction from the control unit 16 described later. The transmission / reception unit 11 includes a pulse generator, a transmission delay unit, a pulser, and the like, and supplies a drive signal to the ultrasonic probe 1. The pulse generator repeatedly generates rate pulses for forming transmission ultrasonic waves at a predetermined rate frequency. The transmission delay unit generates a delay time for each piezoelectric vibrator necessary for focusing the ultrasonic wave generated from the ultrasonic probe 1 into a beam and determining transmission directivity. Give for each rate pulse. The pulser applies a drive signal (drive pulse) to the ultrasonic probe 1 at a timing based on the rate pulse. The transmission delay unit arbitrarily adjusts the transmission direction of the ultrasonic wave transmitted from the piezoelectric vibrator surface by changing the delay time given to each rate pulse.

  The transmission / reception unit 11 has a function capable of instantaneously changing a transmission frequency, a transmission drive voltage, and the like in order to execute a predetermined scan sequence based on an instruction from the control unit 16. In particular, the change of the transmission drive voltage is realized by a linear amplifier type transmission circuit whose value can be switched instantaneously, or a mechanism for electrically switching a plurality of power supply voltages and transmitting a rectangular pulse.

  The transmission / reception unit 11 includes a preamplifier, an A / D (Analog / Digital) converter, a reception delay unit, an adder, and the like. The transmission / reception unit 11 performs various processing on the reflected wave signal received by the ultrasonic probe 1 and reflects it. Generate wave data. The preamplifier amplifies the reflected wave signal for each channel. The A / D converter A / D converts the amplified reflected wave signal. The reception delay unit gives a delay time necessary for determining the reception directivity. The adder performs an addition process of the reflected wave signal processed by the reception delay unit to generate reflected wave data. By the addition processing of the adder, the reflection component from the direction corresponding to the reception directivity of the reflected wave signal is emphasized, and a comprehensive beam for ultrasonic transmission / reception is formed by the reception directivity and the transmission directivity.

  The transmitter / receiver 11 transmits a two-dimensional ultrasonic beam from the ultrasonic probe 1 when the subject P is two-dimensionally scanned. Then, the transmission / reception unit 11 generates two-dimensional reflected wave data from the two-dimensional reflected wave signal received by the ultrasonic probe 1. In addition, when the subject P is three-dimensionally scanned, the transmission / reception unit 11 transmits a three-dimensional ultrasonic beam from the ultrasonic probe 1. Then, the transmission / reception unit 11 generates three-dimensional reflected wave data from the three-dimensional reflected wave signal received by the ultrasonic probe 1.

  The form of the output signal from the transmission / reception unit 11 can be selected from various forms such as a signal including phase information called an RF (Radio Frequency) signal or amplitude information after envelope detection processing. Is possible.

  In addition, when receiving a hardness image display request, the transmission / reception unit 11 transmits a push pulse, which is a focused ultrasonic pulse having a high sound pressure, from the ultrasonic probe 1 based on an instruction from the control unit 16. To displace the living tissue. In the following description, the case where the biological tissue is displaced using the push pulse will be described. However, the embodiment is not limited to this, and for example, the biological tissue is displaced by pressing and releasing the biological surface. It is also applicable to.

  For example, the transmission / reception unit 11 causes the ultrasonic probe 1 to transmit a push pulse having a point in the scanning line area as a focal point. Thereby, the transmission / reception unit 11 generates a plane wave-like shear wave centered on the focal point. Subsequently, the transmission / reception unit 11 transmits a push pulse having a focal point deeper than the focal point where the shear wave is generated. Thereby, the transmission / reception unit 11 generates a plane wave-like shear wave centering on a deeper focal point. As described above, the transmission / reception unit 11 generates shear waves one after another in the living body by transmitting push pulses while shifting the focus position to a deeper position. That is, the transmission / reception unit 11 transmits the push pulse while shifting the focus from a shallow position to a deep position within the push pulse transmission range. Thereby, the transmission / reception part 11 produces | generates the shear wave of the plane wave shape which propagates outward centering around a push pulse transmission range one after another. Here, as an example, a case where a push pulse is transmitted to a plurality of focal points to form a shear wave on a plane wave has been described, but the disclosed technique is not limited to this. For example, a spherical pulse shear wave may be formed by transmitting a push pulse to a single focal point.

  Further, every time the living tissue is displaced, the transmission / reception unit 11 performs transmission / reception of ultrasonic waves for measuring the displacement of the living tissue a plurality of times for each scanning line. For example, every time the transmission / reception unit 11 transmits a push pulse to the ultrasonic probe 1, the transmission / reception unit 11 performs transmission / reception of a tracking pulse for observing the displacement of the living tissue due to the push pulse a plurality of times for each scanning line.

  The signal processing unit 12 performs various types of signal processing on the reflected wave data generated from the reflected wave signal by the transmission / reception unit 11. The signal processing unit 12 receives the reflected wave data from the transmission / reception unit 11, performs logarithmic amplification, envelope detection processing, and the like, and generates data (B-mode data) in which the signal intensity is expressed by brightness. Further, the signal processing unit 12 performs frequency analysis on velocity information from the reflected wave data received from the transmission / reception unit 11 and extracts data (Doppler data) obtained by extracting moving body information such as velocity, dispersion, and power due to the Doppler effect on multiple points. Generate. Here, the moving body is, for example, a blood flow, a tissue such as a heart wall, or a contrast agent.

  When the signal processing unit 12 receives a hardness image display request, the signal processing unit 12 generates hardness distribution information for displaying the hardness of the living tissue in color based on an instruction from the control unit 16. For example, the signal processing unit 12 generates hardness distribution information by measuring the propagation speed of the displacement of the biological tissue generated by the push pulse. Specifically, the signal processing unit 12 receives the reflected wave data of the tracking pulse for observing the displacement of the living tissue from the transmission / reception unit 11, and performs frequency analysis on the received reflected wave data so that it falls within the scanning range. Data (tissue Doppler data) obtained by extracting exercise information based on the Doppler effect of a certain tissue is generated.

  Subsequently, the signal processing unit 12 obtains the displacement by time-integrating the velocity component of the tissue Doppler data. Subsequently, the signal processing unit 12 acquires the time when the displacement obtained at the scanning position reaches a peak as the arrival time of the shear wave. Subsequently, the signal processing unit 12 calculates the propagation velocity of the displacement from the acquired arrival time of the shear wave. For example, the signal processing unit 12 calculates the propagation velocity of the displacement at each scanning position by performing spatial differentiation of the arrival time of the shear wave at the scanning position. Then, the signal processing unit 12 generates the hardness distribution information by color-coding the calculated propagation velocity of the displacement and mapping it to the corresponding position. Since the hard tissue is harder to be deformed, the strain value of the hard tissue becomes smaller and the strain value of the soft biological tissue becomes larger. That is, the strain value is a value indicating the hardness (elastic modulus) of the tissue. That is, the tracking pulse is a transmission pulse for tissue Doppler. Note that the above elastic modulus may be calculated by the signal processing unit 12 detecting the tissue displacement between adjacent frames based on the cross-correlation of ultrasonic reception RF signals. In such a case, the tracking pulse is a transmission pulse for the B mode.

  The reason why the hardness distribution information is generated from the propagation speed of the displacement is that the following formulas (1) and (2) hold.

Here, in the above formulas (1) and (2), v _s indicates the propagation speed of the shear wave, G indicates the shear elastic modulus, ρ indicates the density, and E indicates the Young's modulus. Σ indicates a Poisson's ratio. For example, by assuming that the Poisson's ratio of the living tissue approximates σ = 0.5 and the density is ρ = 1.0, the shear wave propagation velocity v _s , Young's modulus E, and shear modulus G can be mutually converted. It becomes. For this reason, any of shear wave propagation velocity v _s , Young's modulus E, and shear modulus G can be used as a physical quantity representing the hardness of a living tissue. In the present embodiment, a case of using the propagation velocity v _s of the shear waves as a physical quantity representing the hardness of the biological tissue.

  The image generation unit 13 generates ultrasonic image data from the data generated by the signal processing unit 12. That is, the image generation unit 13 generates two-dimensional B-mode image data in which the intensity of the reflected wave is represented by luminance from the two-dimensional B-mode data generated by the signal processing unit 12. Further, the image generation unit 13 generates two-dimensional Doppler image data representing moving body information from the two-dimensional Doppler data generated by the signal processing unit 12. The two-dimensional Doppler image data is velocity image data, distributed image data, power image data, or image data obtained by combining these.

  Here, the image generation unit 13 generally converts (scan converts) a scanning line signal sequence of ultrasonic scanning into a scanning line signal sequence of a video format represented by a television or the like, and displays ultrasonic waves for display. Generate image data. Specifically, the image generation unit 13 generates ultrasonic image data for display by performing coordinate conversion according to the ultrasonic scanning mode of the ultrasonic probe 1. In addition to the scan conversion, the image generation unit 13 may perform various image processing, such as image processing (smoothing processing) for regenerating an average luminance image using a plurality of image frames after scan conversion, Image processing (edge enhancement processing) using a differential filter is performed in the image. The image generation unit 13 synthesizes incidental information (character information of various parameters, scales, body marks, etc.) with the ultrasonic image data.

  That is, B-mode data and Doppler data are ultrasonic image data before scan conversion processing, and data generated by the image generation unit 13 is ultrasonic image data for display after scan conversion processing. The B-mode data and the Doppler data are also called raw data (Raw Data).

  The image generation unit 13 generates hardness image data in which the hardness of the living tissue is displayed in color from the hardness distribution information generated by the signal processing unit 12. FIG. 2 is a diagram illustrating an example of hardness image data generated by the image generation unit 13. As shown in FIG. 2, the image generation unit 13 causes the monitor 2 to display an image in which the hardness of the living tissue is color-coded.

  The image memory 14 is a memory that stores image data for display generated by the image generation unit 13. The image memory 14 can also store the signal processing unit 12 and data generated by the signal processing unit 12. The B-mode data and Doppler data stored in the image memory 14 can be called by an operator after diagnosis, for example, and become ultrasonic image data for display via the image generation unit 13.

  The internal storage unit 15 stores a control program for performing ultrasonic transmission / reception, image processing, and display processing, diagnostic information (for example, patient ID, doctor's findings, etc.), various data such as a diagnostic protocol and various body marks. To do. The internal storage unit 15 is also used for storing image data stored in the image memory 14 as necessary. The data stored in the internal storage unit 15 can be transferred to an external device.

  The control unit 16 controls the entire processing of the ultrasonic diagnostic apparatus. Specifically, the control unit 16 is based on various setting requests input from the operator via the input unit 3 and various control programs and various data read from the internal storage unit 15. The process of the part 12, the signal processing part 12, and the image generation part 13 is controlled. Further, the control unit 16 performs control so that the display image data stored in the image memory 14 or the internal storage unit 15 is displayed on the monitor 2. Further, the control unit 16 performs control so that the display image data generated by the image generation unit 13 is stored in the internal storage unit 15 or the like. Further, the control unit 16 performs control so that medical image data received from the operator via the input unit 3 is transferred from the external device 6 to the internal storage unit 15 and the image generation unit 13 via the network.

  The overall configuration of the ultrasonic diagnostic apparatus according to the first embodiment has been described above. With this configuration, the ultrasonic diagnostic apparatus according to the first embodiment visualizes the hardness of a living tissue by elastography.

  By the way, every time a conventional ultrasonic diagnostic apparatus transmits a push pulse, the transmission and reception of a tracking pulse for observing the displacement of a living tissue due to the push pulse is executed numerous times for each scanning line. This is because it is necessary to make the time resolution fine enough to obtain the time when the displacement reaches the peak in the scanning line. For this reason, every time the conventional ultrasonic diagnostic apparatus transmits a push pulse, the tracking pulse is transmitted and received on one scanning line repeatedly, for example, about 100 times. Hereinafter, elastography performed by a conventional ultrasonic diagnostic apparatus will be specifically described.

3 and 4 are diagrams for explaining transmission and reception of push pulses and tracking pulses. In FIG. 3, transmission and reception unit 11, to send push pulse to the point 3a and focus, illustrating a case of observing the propagation speed of the displacement of the biological tissue in the N of each scan line y ₁ ~y _N. Specifically, in FIG. 3, at point 3a and depth direction at a plurality of points of observation points 3b1~3bN and each observation point near on the scanning line y ₁ ~y _N in the same position, observing the propagation velocity The case where it does is illustrated. The horizontal direction in FIG. 3 indicates the position of each scanning line in the azimuth direction, and the vertical direction indicates the depth direction. In the example shown in FIG. 2, the transmission position of the push pulse in the azimuth direction and y _0. Also, the observation point 3b1~3bN is a point on each scan line _y 1 ~y _N.

As shown in FIG. 3, when observing the propagation velocity at a plurality of points of observation points 3b1 and its vicinity on the scanning line y ₁ is transmitting and receiving unit 11 transmits a first push pulse to the point 3a and focus is, then, a tracking pulse is sent multiple times received over the scanning lines y _1. When observing the propagation velocity at a plurality of points of observation points 3b2 and its vicinity on the scanning line y ₂ includes a transmitting and receiving unit 11, to send a second push pulse to the point 3a the focus, then, the scanning lines y ₂ transmits and receives a tracking pulse a plurality of times. Further, when observing the propagation velocity at a plurality of points of observation points 3bN and its vicinity on the scanning line y _N is transmitting and receiving unit 11, to send a N-th push pulses point 3a the focus, then scanned tracking pulse is sent multiple times received on the line y _N. In the following, the number of tracking pulse transmissions that are transmitted and received a plurality of times on one scanning line may be referred to as “M”. For example, the number of transmissions of the tracking pulse transmitted / received on one scanning line is, for example, 100 times.

  FIG. 4 illustrates transmission times of push pulses and tracking pulses transmitted to observe the displacement of the living tissue. The horizontal axis in FIG. 4 indicates the transmission time of the transmitted ultrasonic pulse, and the vertical axis indicates the transmission voltage of the transmitted ultrasonic pulse. The shaded area in the figure indicates the transmission of a push pulse, and the upward arrow indicates the transmission of a tracking pulse. Also, as shown in FIG. 4, the push pulse is transmitted for a very long time (approximately 200 to 2000 microseconds) compared to the tracking pulse.

As shown in FIG. 4, the transmission / reception unit 11 transmits the _first push pulse from the transmission time t ₁ in order to observe the displacement of the living tissue on the scanning line y ₁ . When the transmission of the first push pulse is completed, the transmission / reception unit 11 transmits / receives the tracking pulse _M times at the transmission times t _1-1 , t _1-2 , t _1-3 ,. Let Then, the transmitter / receiver 11 transmits a second push pulse from the transmission time t ₂ in order to measure the displacement of the living tissue on the scanning line y ₂ . When the transmission of the second push pulse is completed, the transmission / reception unit 11 transmits and receives the tracking pulse _M times at the transmission time t _2-1 , t _2-2 , t _2-3 ,. Let The transmitting and receiving unit 11, in order to measure the displacement of the biological tissue on the scan line y _N, and transmits the N-th push pulses from transmission time t _N. When the transmission of the Nth push pulse is completed, the transmission / reception unit 11 transmits / receives the tracking pulse _M times at the transmission times t _N−1 , t _N−2 , t _N−3 ,. Let

  FIG. 5A to FIG. 5C are diagrams for explaining the process of acquiring the arrival time of the shear wave. For example, the signal processing unit 12 acquires the time when the displacement reaches a peak at each scanning position as the arrival time of the shear wave. FIG. 5A shows the time change of the displacement of the living tissue at the observation point 3b1, FIG. 5B shows the time change of the displacement of the living tissue at the observation point 3b2, and FIG. 5C shows the time of the displacement of the living tissue at the observation point 3bN. Showing change. 5A to 5C, the horizontal axis indicates the time elapsed after the push pulse transmission, and the vertical axis indicates the displacement of the living tissue at each observation point.

As shown in FIG. 5A, the signal processor 12, the time T ₁ which displacement reaches the peak at the observation point 3b1, obtained as the arrival time T ₁ of the shear wave at the observation point 3b1. Further, as shown in FIG. 5B, the signal processor 12, the time T ₂ which displacement has a peak at the observation point 3b2, obtained as the arrival time T ₂ of the shear waves at the observation point 3b2. Further, as shown in FIG. 5C, the signal processor 12, the time T _N of displacement at the observation point 3BN reaches a peak is acquired as the arrival time T _N of shear waves at the observation point 3BN.

  FIG. 6 is a diagram for explaining processing for observing the propagation velocity of displacement. In FIG. 6, the horizontal direction indicates the position of each scanning line in the azimuth direction, and the vertical direction indicates the time from when the push pulse is transmitted until the Mth tracking pulse is transmitted.

As illustrated in FIG. 6, the signal processing unit 12 calculates the propagation speed of the shear wave from the acquired arrival time of the shear wave. When the push pulse is sent to the point 3a, the time arrival of shear waves in the observation point 3b1 scan line y ₁ is reached is T _1. Further, when the push pulse to the point 3a is transmitted, the time arrival of shear waves at the observation point 3b2 of the scan line y ₂ is reached is T _2. Further, when the push pulse is sent to the point 3a, the time arrival of shear waves at the observation point 3bN scan line y _N arrives is T _N. In FIG. 6, the slopes of the shear wave arrival times T _{1 to} T _{N in} the scanning lines y _{1 to} y _N correspond to the propagation speed of the displacement. For example, the signal processing unit 12, by performing spatial differentiation of the arrival time _T 1 through T _N of shear waves in each scan line _y 1 ~y _N, the displacement of each point on each scan line _y 1 ~y _N Is calculated.

  Thus, the conventional ultrasonic diagnostic apparatus observes the propagation speed of displacement. The conventional ultrasonic diagnostic apparatus performs elastography by generating hardness distribution information by color-coding the propagation velocity of the observed displacement and mapping it to the corresponding position.

  Here, as described above, the conventional ultrasonic diagnostic apparatus tracks each scanning line in the scanning region every time a push pulse is transmitted in order to measure the hardness of a living tissue in elastography. Transmit and receive pulses M times. That is, in order to measure the propagation speed of displacement on N scanning lines, transmission / reception of tracking pulses is performed N × M times. For this reason, in the conventional ultrasonic diagnostic apparatus, the ultrasonic probe 1 is likely to generate heat due to transmission / reception of the tracking pulse. In particular, an ultrasonic diagnostic apparatus that cannot perform parallel simultaneous reception in which a reflected wave signal is received by a plurality of scanning lines with respect to one transmission of a tracking pulse, or an ultrasonic diagnosis apparatus that can perform parallel simultaneous reception by only a few scanning lines. The possibility of heat generation increases as the ultrasonic diagnostic apparatus increases.

  Therefore, the ultrasonic diagnostic apparatus according to the first embodiment executes the processing of the control unit 16 described below in order to suppress the heat generation of the ultrasonic probe when measuring the hardness of the living tissue.

  The control unit 16 according to the first embodiment sets an observation period for observing the propagation of the displacement of the living tissue based on the propagation speed, and performs a plurality of ultrasonic waves executed on each scanning line by the transmission / reception unit 11. Transmission and reception are executed for the observation period. For example, the control unit 16 determines the observation period for each scanning line using at least one of the upper limit value and the lower limit value of the propagation speed at which the displacement of the living tissue propagates.

For example, the control unit 16 determines the expected speed of the propagation speed, and determines the observation period based on the determined expected speed. Specifically, the internal storage unit 15 stores an upper limit value and a lower limit value of the estimated speed of propagation speed for each diagnostic part such as liver, kidney, mammary gland, and disease type. The control unit 16 refers to the upper limit value and lower limit value of the expected speed stored in the internal storage unit 15 to determine the upper limit value and lower limit value of the expected speed according to the diagnosis site and the disease type. Then, the control unit 16, the scanning lines y _k, calculates time to reach the displacement at the upper limit value of the estimated speed and the time to reach the displacement at the lower limit value of the estimated velocity, respectively. Then, the control unit 16, the intervals of time calculated is set as the observation time of the scan line y _k. And the control part 16 performs transmission / reception of a tracking pulse about the observation period set for every scanning line. Note that the upper limit value and the lower limit value of the expected speed stored in the internal storage unit 15 are calculated by, for example, totaling past diagnosis records for each diagnosis region and disease type. In addition, here, a case has been described in which the upper limit value and the lower limit value of the expected speed are determined according to the diagnosis site and the type of disease, but the embodiment is not limited to this, for example, ultrasonic diagnosis An arbitrary value may be input by a user who uses the apparatus. In addition, here, the case where the observation period is set for each of a plurality of scanning lines has been described, but the embodiment is not limited to this, and for example, a uniform observation period is set for all the scanning lines. Also good.

  FIG. 7 is a diagram for explaining processing of the control unit 16 according to the first embodiment. In FIG. 7, the horizontal direction indicates the position of each scanning line in the azimuth direction, and the vertical direction indicates the time from when the push pulse is transmitted until the Mth tracking pulse is transmitted. Further, FIG. 7 shows a line 7a corresponding to the upper limit value of the expected displacement speed and a line 7b corresponding to the lower limit value of the expected displacement speed.

As illustrated in FIG. 7, for example, the control unit 16 causes the transmission / reception unit 11 to perform transmission / reception of the tracking pulse during the observation period surrounded by the line 7 a and the line 7 b. Thereby, the transmission / reception unit 11 causes the ultrasonic probe 1 to perform transmission / reception of the tracking pulse for the observation period each time the push pulse is transmitted. More specifically, the control unit 16, in order to measure the propagation velocity of the displacement on the scan line y ₁ after the transmission push pulses to perform the transmission and reception of the tracking pulse for observation period 7c surrounded by the line 7a and the line 7b . In other words, the control unit 16 does not cause the transmission / reception unit 11 to perform transmission / reception of the tracking pulse for the period 7d and the period 7e. The control unit 16, in order to measure the propagation velocity of the displacement on the scan line y _N after transmitting the push pulses, the observation period 7f surrounded by the line 7a and the line 7b to perform transmission and reception of tracking pulses. In other words, the control unit 16 does not cause the transmission / reception unit 11 to perform transmission / reception of the tracking pulse for the period 7g. As described above, the control unit 16 causes the transmission / reception unit 11 to perform transmission / reception of the tracking pulse for each scanning line during the observation period surrounded by the line 7a and the line 7b. On the other hand, the control unit 16 does not execute transmission / reception of the tracking pulse in a period earlier than the line 7a and a period later than the line 7b. For this reason, the control part 16 can reduce the frequency | count of transmission of a tracking pulse. In addition, although the case where the control unit 16 executes transmission / reception of tracking pulses in the observation period surrounded by the line 7a and the line 7b has been described here, the embodiment is not limited thereto. For example, the control unit 16 may execute tracking pulse transmission / reception for a period later than the line 7a or a period earlier than the line 7b.

  Next, a processing procedure of the ultrasonic diagnostic apparatus according to the first embodiment will be described with reference to FIG. FIG. 8 is a flowchart for explaining an example of a processing procedure of the ultrasonic diagnostic apparatus according to the first embodiment.

  As shown in FIG. 8, when the input unit 3 receives an input of a hardness image display request (Yes in step S101), the control unit 16 causes the transmission / reception unit 11 to push a pulse that focuses on a certain point in the scanning region. Is transmitted (step S102). Note that the control unit 16 does not start the processing illustrated in FIG. 8 until the input unit 3 receives an input of a hardness image display request (No in step S101).

  Subsequently, the control unit 16 causes the transmission / reception unit 11 to perform transmission / reception of tracking pulses for the observation period of each scanning line (step S103). Thereby, the transmission / reception unit 11 causes the ultrasonic probe 1 to perform transmission / reception of the tracking pulse for the observation period of each scanning line.

  Subsequently, the control unit 16 determines whether or not tracking pulse transmission / reception has been executed for all scanning lines (step S104). Here, when tracking pulse transmission / reception is not executed for all the scanning lines (No in step S104), the control unit 16 proceeds to the process of step S103.

  When tracking pulse transmission / reception has been executed for all scanning lines (Yes in step S104), the control unit 16 determines whether or not push pulses have been transmitted for all focal points (step S105). Here, when the push pulse is not transmitted for all the focal points (No at Step S105), the control unit 16 proceeds to the process at Step S102.

  When the push pulse is transmitted for all the focal points (Yes at Step S105), the control unit 16 causes the signal processing unit 12 to measure the propagation speed of the shear wave (Step S106). Subsequently, the control unit 16 generates hardness image data based on the measured propagation velocity (step S107). And the control part 16 displays the produced | generated hardness image data on the monitor 2 (step S108).

  The ultrasonic diagnostic apparatus does not necessarily have to be executed according to the above processing procedure. For example, the process of step S106 for measuring the propagation speed of the shear wave may be executed after the process of step S104.

  As described above, the ultrasonic diagnostic apparatus according to the first embodiment transmits and receives ultrasonic waves for measuring the displacement of a living tissue every time the living tissue is displaced by acoustic radiation force or mechanical vibration. This is executed a plurality of times for each of the plurality of scanning lines in the scanning line region. Then, the ultrasonic diagnostic apparatus according to the first embodiment sets an observation period for observing the propagation of the displacement of the living tissue based on the propagation speed, and a plurality of times executed on each scanning line by the transmission / reception unit 11. Ultrasonic transmission / reception is executed for the observation period. For this reason, the ultrasonic diagnostic apparatus according to the first embodiment can reduce the number of tracking pulse transmissions and, as a result, can suppress heat generation.

  In addition, for example, the ultrasonic diagnostic apparatus can reduce the number of tracking pulse transmissions, thereby reducing the time required for data collection and improving the frame rate.

(Second Embodiment)
In the first embodiment, the case where the number of tracking pulse transmissions is reduced has been described. Therefore, in the second embodiment, a case where the number of push pulse transmissions is reduced in addition to the number of tracking pulse transmissions will be described. Note that all of the functional configurations described in the first embodiment are applied to the ultrasonic diagnostic apparatus according to the second embodiment, except for processing for reducing the number of push pulse transmissions.

  The control unit 16 according to the second embodiment classifies the plurality of scanning lines into groups in which observation periods do not overlap, and each time the living tissue is displaced once, one or more included in one group classified Transmission / reception of ultrasonic waves is executed for a plurality of scanning lines.

FIG. 9 is a diagram for explaining processing of the control unit 16 according to the second embodiment. In the example illustrated in FIG. 9, a case will be described in which a group in which the observation periods do not overlap is extracted from the observation periods at the positions y _{1 to} y ₁₁ . In FIG. 9, the horizontal direction indicates the position of each scanning line in the azimuth direction, and the vertical direction indicates the time from when the push pulse is transmitted until the Mth tracking pulse is transmitted.

As illustrated in FIG. 9, the control unit 16 specifies a scanning line included in the same group as the scanning line y ₁ . For example, the control unit 16 compares the observation period of the scanning line y _{1 with} the observation periods of the scanning lines y _{2 to} y ₁₁ , and specifies the scanning line y ₄ that does not overlap the scanning period y ₁ . Subsequently, the control unit 16, the observation period and observation period _{y 4} of the scan line _{y 1,} the observation period of each scan line _y 5 _{~y 11} compares each of the scanning lines _{y 11} where observation period does not overlap Identify. Then, the control unit 16 classifies the scanning lines y ₁ , y ₄ and y ₁₁ into the group A. The control unit 16 identifies the scan lines included in the same group as the scan line y _2. For example, the control unit 16 compares the observation period of the scanning line y _{2 with} the observation periods of the scanning lines y _{3 to} y ₁₁ and identifies the scanning line y ₆ that does not overlap the scanning period y ₂ . Then, the control unit 16 classifies the scanning lines y ₂ and y ₆ into the group B. The control unit 16 identifies the scan lines included in the same group as the scan line y _3. For example, the control unit 16 compares the observation period of the scanning line y _{3 with} the observation periods of the scanning lines y _{4 to} y ₁₁ , and specifies the scanning line y ₉ that does not overlap the scanning period y ₃ . Then, the control unit 16 classifies the scanning lines y ₃ and y ₉ into the group C. Further, the control unit 16 sets the scanning lines y ₅ , y ₇ , y _8, and y ₁₀ as the groups D, E, F, and G independently because there are no scanning lines that do not overlap the observation periods. As described above, the control unit 16 identifies the scanning lines whose observation periods do not overlap between the scanning lines, and identifies the scanning lines included in the same group as each scanning line.

And, for example, when observing the displacement propagation velocity for group A, the control unit 16 transmits the push pulse once and then transmits and receives the tracking pulse on the scanning line y ₁ for the observation period 9a. observation period 9b causes the transmit and receive tracking pulses on the scan line y _4, the observation period. 9c to transmit and receive the tracking pulses on the scan line y _11. That is, since the transmission / reception unit 9 does not transmit the push pulse for observing the scanning line y ₄ and the push pulse for observing the scanning line y ₁₁ , the number of push pulse transmissions can be reduced. In the example illustrated in FIG. 9, it is only necessary to transmit the push pulse once for each of the groups A to G, and thus it is possible to observe 11 scanning lines by transmitting a total of 7 push pulses.

  As described above, the ultrasonic diagnostic apparatus according to the second embodiment executes tracking pulse transmission / reception each time a shear wave is generated for a plurality of scanning lines in which the observation periods of the scanning lines do not overlap. For this reason, the ultrasonic diagnostic apparatus according to the second embodiment can reduce heat generation as a result of reducing the number of push pulse transmissions.

  In addition, for example, the ultrasonic diagnostic apparatus can reduce the number of push pulse transmissions, thereby reducing the time required for data collection and improving the frame rate.

(Third embodiment)
In the first embodiment, the case where the observation period is set based on the expected speed of the propagation speed of the displacement has been described, but the present invention is not limited to this. For example, the observation period may be set based on the observed displacement of the living tissue. Therefore, in the third embodiment, a case where the observation period is set based on the observed displacement of the living tissue will be described. The ultrasonic diagnostic apparatus according to the third embodiment applies all of the functional configurations described in the first embodiment except for the process for setting the observation period based on the observed displacement of the living tissue. Is done.

  The control part 16 which concerns on 3rd Embodiment determines the said observation period based on the measured value of the propagation speed which the displacement of a biological tissue propagates. For example, when the input unit 3 accepts a display request for a hardness image, the control unit 16 causes the transmission / reception unit 11 to transmit a push pulse that focuses on a certain point in the scanning region. And the control part 16 performs transmission / reception of a tracking pulse in multiple times with a predetermined scanning line. Thereby, the control part 16 acquires the arrival time of the shear wave in a predetermined scanning line. And the control part 16 sets the start time of an observation period by subtracting predetermined time from the arrival time of the acquired shear wave. Moreover, the control part 16 sets the end time of an observation period by adding predetermined time to the arrival time of the acquired shear wave. Note that the control unit 16 sets the observation period on the scanning line where the displacement of the living tissue is not observed based on the observation period set by the scanning line at a position close to the scanning line. As described above, when the observation period of each scanning line is determined, the control unit 16 causes the transmission / reception unit 11 to perform transmission and reception of the tracking pulse for the determined observation period as described in the first embodiment.

FIG. 10 is a diagram for explaining processing of the control unit 16 according to the third embodiment. In FIG. 10, the horizontal direction indicates the position of each scanning line in the azimuth direction, and the vertical direction indicates the time from when the push pulse is transmitted until the Mth tracking pulse is transmitted. The origin corresponds to the position on the ultrasonic probe 1 where the push pulse is transmitted. Further, y ₀ indicates the transmission position of the push pulse in the azimuth direction.

As shown in FIG. 10, for example, the control unit 16 observes the displacement of the living tissue on the measurement scanning lines y ₂ , y ₆ and y ₁₀ , and for example, reaches the shear wave arrival times T ₂ and T _6. and _{T 10} to get, respectively. Then, the control unit 16 subtracts the predetermined time dT2 from the arrival time T ₂ of the acquired shear waves, determining the time of the start point 10a of the observation period of the scan line y _2. The control unit 16 subtracts the predetermined time dT6 from the arrival time T ₆ of the obtained shear waves, determining the time of the start point 10b of the observation period of the scan line y _6. The control unit 16 subtracts the predetermined time dT10 from the arrival time _{T 10} of the acquired shear waves, determining the time of the start point 10c of the observation period of the scan line _{y 10.} Then, the control unit 16 uses the line segment connecting _{y 0} as the start point 10a, the starting point 10a and the starting point 10b, the start point 10b and the starting point 10c, respectively, to determine the start time of the observation period in each scan line .

The control unit 16, by adding a predetermined time dT2 the arrival time T ₂ of the acquired shear waves, determining the time of the end point 10d of the observation period of the scan line y _2. The control unit 16, by adding a predetermined time dT6 the arrival time T ₆ of the obtained shear waves, determining the time of the end point 10e of the observation period of the scan line y _6. The control unit 16, by adding a predetermined time dT10 to the arrival time _{T 10} of the acquired shear waves, determining the time of the end point 10f of the observation period of the scan line _{y 10.} Then, the control unit 16 uses the line segment connecting _{y 0} and the end point 10d, and the end point 10d end point 10e, the end point 10f and the end point 10e respectively, to determine the end time of the observation period in each scan line . For example, an arbitrary scanning line may be set in advance by the user, or may be selected at random when the input unit 3 receives a display request for a hardness image. The predetermined time dT2, DT6 and DT10, for example, may be any value is set in advance by the user, it may be determined according to the distance between the scanning lines and y _0. In addition, here, the case where the control unit 16 transmits a push pulse and a tracking pulse for measuring the displacement of the living tissue when the input unit 3 receives a hardness image display request has been described. The form is not limited to this. For example, when the hardness image data when the elastography is performed on the same cross section of the subject is stored in the image memory 14, the control unit 16 sets the observation period using the hardness image data. May be.

  As described above, the ultrasonic diagnostic apparatus according to the third embodiment sets the observation period based on the measured displacement of the living tissue. For this reason, the ultrasonic diagnostic apparatus according to the third embodiment can appropriately set the observation period. As a result, the number of tracking pulse transmissions can be efficiently reduced, and heat generation can be suppressed.

(Fourth embodiment)
In the third embodiment, the case has been described in which the displacement of the living tissue is observed with respect to the scanning line for actual measurement, and the observation period is set based on the actual measurement value of the observed propagation velocity. Here, in the embodiment, an observation period may be set for the scanning line for actual measurement. In such a case, the control unit 16 causes the ultrasonic wave to be transmitted and received a plurality of times for the observation period set using the estimated propagation speed, and resets the observation period based on the actually measured propagation speed. To do.

  Specifically, when the input unit 3 receives a hardness image display request, the control unit 16 determines an upper limit value and a lower limit value of the expected speed according to the diagnosis site and the type of the disease. Then, the control unit 16 calculates a time for the displacement to reach the upper limit value of the expected speed and a time for the displacement to reach the lower limit value of the expected speed for the measurement scanning line. Then, the control unit 16 sets the calculated time interval as the observation time of the scanning line for actual measurement. Then, the control unit 16 causes the transmission / reception unit 11 to transmit a push pulse. And the control part 16 performs transmission / reception of a tracking pulse in multiple times about the set observation period for every scanning line for measurement. Thereby, the control part 16 acquires the arrival time of the shear wave in the scanning line for measurement. And the control part 16 resets the start time of an observation period by subtracting predetermined time from the arrival time of the acquired shear wave. Moreover, the control part 16 resets the end time of an observation period by adding predetermined time to the arrival time of the acquired shear wave. Note that the control unit 16 sets the observation period on the scanning line where the displacement of the living tissue is not observed based on the observation period set by the scanning line at a position close to the scanning line. As described above, when the observation period of each scanning line is reset, the control unit 16 causes the transmission / reception unit 11 to perform transmission / reception of the tracking pulse for the reset observation period as described in the first embodiment.

  As described above, the control unit 16 sets the observation period of the scanning line for actual measurement using the estimated propagation speed. And the control part 16 performs transmission / reception of an ultrasonic wave several times about the observation period set for every scanning line for measurement. And the control part 16 resets an observation period based on the measured value of the observed propagation velocity. For this reason, the ultrasonic diagnostic apparatus according to the fourth embodiment can efficiently reduce the number of tracking pulse transmissions even when observing a scanning line for measurement, and can suppress heat generation.

(Other embodiments)
Although several embodiments have been described so far, the technology disclosed in the present application is not limited to these embodiments. That is, these embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made.

  For example, the first to third embodiments described above can be applied to a case where parallel simultaneous reception is performed in which reflected wave signals are received by a plurality of scanning lines with respect to transmission of one tracking pulse.

  For example, the control methods described in the first and second embodiments described above can be realized by executing a control program prepared in advance on a computer such as a personal computer or a workstation. This control program can be distributed via a network such as the Internet. The control program is recorded on a computer-readable non-transitory recording medium such as a hard disk, a flexible disk (FD), a CD-ROM, an MO, a DVD, a flash memory such as a USB memory and an SD card memory. It can also be executed by being read from a non-transitory recording medium by a computer.

  According to at least one embodiment described above, it is possible to suppress the heat generation of the ultrasonic probe when measuring the hardness of a living tissue.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 10 Apparatus main body 11 Transmission / reception part 16 Control part

Claims (6)

Transmitter / receiver that performs transmission / reception of ultrasonic waves for measuring the displacement of the living tissue a plurality of times for each of the plurality of scanning lines in the scanning line area every time the living tissue is displaced by acoustic radiation force or mechanical vibration When,
With reference to information in which the upper limit and the lower limit of the expected speed of the propagation speed are associated with each diagnosis site or each disease type, the upper and lower limits of the expected speed corresponding to the specified diagnosis site or disease type And a control unit that determines an observation period for each scanning line and executes transmission / reception of ultrasonic waves performed on each scanning line by the transmission / reception unit for the observation period. Ultrasound diagnostic device.   2. The control unit according to claim 1, wherein the control unit determines the observation period for each of the plurality of scanning lines, and performs transmission and reception of the plurality of ultrasonic waves for the observation period determined for each scanning line. Ultrasound diagnostic equipment.   The control unit classifies the plurality of scanning lines into a plurality of groups based on the observation period determined for each scanning line, and is included in one group that is classified each time the living tissue is displaced. The ultrasonic diagnostic apparatus according to claim 2, wherein transmission / reception of the ultrasonic wave is executed with respect to a scanning line. The control unit acquires an actual value of the propagation velocity for the actual scanning line among the plurality of scanning lines, and based on the acquired actual measurement value, an upper limit and a lower limit of the expected speed of the actual scanning line And determining the observation period of the actual scan line based on the determined upper and lower limits of the expected speed of the actual scan line, and determining the determined actual scan line The ultrasonic diagnostic apparatus according to claim 1, wherein the observation period of scanning lines other than the actual scanning line among the plurality of scanning lines is determined based on an observation period.   The control unit causes the ultrasonic wave to be transmitted and received a plurality of times for the observation period determined using the expected speed of the propagation speed, and re-determines the observation period based on the actually measured value of the propagation speed. The ultrasonic diagnostic apparatus according to any one of claims 1 to 3, wherein Transmission / reception procedure for transmitting / receiving ultrasonic waves for measuring the displacement of the living tissue multiple times for each of the plurality of scanning lines in the scanning line area every time the living tissue is displaced by acoustic radiation force or mechanical vibration When,
With reference to information in which the upper limit and the lower limit of the expected speed of the propagation speed are associated with each diagnosis site or each disease type, the upper and lower limits of the expected speed corresponding to the specified diagnosis site or disease type And determining the observation period for each scanning line, and causing the computer to execute a control procedure for executing transmission / reception of ultrasonic waves executed on each scanning line by the transmission / reception procedure for the observation period. A characteristic control program.

Images