JP2015198843A - Ultrasonic diagnostic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate measurement of elasticity of a biological tissue.SOLUTION: Pulse vibration 16 is applied to a probe 10 with the motion of a user's hand and vibration is applied to a subject 14 with the vibration of the probe 10 to excite a shear wave in the tissue of the subject 14. The pulse vibration can be generated by giving the subject 14 shock obtained by weakening pressure immediately after the user applies the pressure to the subject 14 via the probe 10 with his/her hand in the state where the user holds the probe 10 brought into contact with the subject 14. In the ultrasonic diagnostic device, the pulse vibration 16 is applied to the subject 14, the ultrasonic wave is transmitted/received in the probe 10, and the elastic modulus distribution of the biological tissue is measured on the basis of the ultrasonic wave received by the probe 10.

Description

  The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to an apparatus for measuring elastic characteristics of a living tissue.

  2. Description of the Related Art Ultrasonic diagnostic apparatuses that measure the elastic modulus of living tissue are widely used. The elastic modulus is defined as a value obtained by dividing the stress applied to an elastically deformed object by the distortion of the object, and represents the difficulty of deformation of the object. In general, a tissue having a disease such as cancer, arteriosclerosis, or cirrhosis has an elastic modulus different from that of other tissues. Therefore, it is often possible to find a disease by measuring the elastic modulus.

  As described in Patent Documents 1 and 2, in an ultrasonic diagnostic apparatus that measures an elastic modulus, a shear wave (shear wave) is generated in a living tissue by a vibrating body, and at the tomographic plane by transmitting and receiving ultrasonic waves. Some obtain ultrasonic data. In this ultrasonic diagnostic apparatus, the shear wave propagation velocity distribution on the tomographic plane is obtained based on the ultrasonic data, and the elastic modulus distribution on the tomographic plane is obtained.

  In addition, there is an ultrasonic diagnostic apparatus that generates a shear wave in a living tissue by vibrating a single probe with a vibrating body and measures the propagation speed of the shear wave with a single probe. In this apparatus, an average elastic modulus on the ultrasonic beam axis is measured.

  As described above, there is an ultrasonic diagnostic apparatus that generates a shear wave in a biological tissue by an acoustic radiation pressure in addition to an ultrasonic diagnostic apparatus that generates a shear wave in a biological tissue by a vibrating body. In this ultrasonic diagnostic apparatus, high-energy ultrasonic waves are transmitted from a probe, and shear waves are generated in a living tissue by acoustic radiation pressure. At the same time, ultrasonic data on the tomographic plane is acquired by transmission / reception of ultrasonic waves, a propagation velocity distribution of shear waves on the tomographic plane is obtained based on the ultrasonic data, and further a distribution of elastic modulus is obtained.

International Publication No. 2011-004661 Specification International Publication No. 2011-001776 Specification International Publication No. 2013-073304 Specification

Thomas Deffieux, Jean-Luc Gennisson, Jeremy Bercoff, and Mickael Tanter, “On the Effects of Reflected Waves in Transient Shear Wave Elastography”, IEEE Transactions on ultrasocics, ferroelectrics, and frequency control, vol.58, No.10, October pp 2032-2035, 2011.

  An ultrasonic diagnostic apparatus that generates a shear wave in a living tissue by applying vibration to the living tissue with a vibrating body requires a mechanism for generating the vibration, and thus the configuration is complicated. In addition, in an ultrasonic diagnostic apparatus that generates shear waves in a living tissue by acoustic radiation pressure, high-energy ultrasonic waves are used, so that it is difficult to measure a portion having a large reflection coefficient for ultrasonic waves.

  An object of this invention is to simplify the measurement of the elastic characteristic of a biological tissue.

  The present invention relates to a probe that vibrates biological tissue by a user's hand movement, a transmission / reception unit that transmits / receives ultrasonic waves to / from the probe, and a tomographic frame of the biological tissue based on reception data output from the transmission / reception unit A frame data generation unit that generates data, and a calculation unit that obtains elastic characteristics in a tomographic plane of the living tissue based on a plurality of tomographic frame data generated over time by the frame data generation unit, and The calculation unit includes a propagation characteristic analysis unit that obtains shear wave propagation characteristics based on the plurality of tomographic frame data, and a filter that performs filtering processing on the propagation characteristics to remove or reduce a reflected wave component of the shear wave A processing unit; and an elastic characteristic analysis unit that obtains the elastic characteristic based on the propagation characteristic after the filtering process. It is characterized in.

  The present invention includes a probe in which vibration is applied to a living tissue through a probe by the movement of a user's hand. Thereby, a shear wave can be generated in the living tissue without providing a mechanism for generating vibration. Therefore, the configuration of the ultrasonic diagnostic apparatus is simplified and measurement is facilitated. Based on multiple tomographic frame data, shear wave propagation characteristics are obtained, and when obtaining elastic characteristics from the propagation characteristics, the required elasticity can be obtained by reducing or eliminating the contribution of the reflected wave component of the shear wave toward the probe. The accuracy of characteristics is improved. In view of the above, the present invention includes a filter processing unit that performs a filtering process for removing or reducing the reflected wave component of the shear wave on the propagation characteristics of the shear wave.

  Preferably, the probe includes a plurality of vibration elements arranged in a line, and the transmission / reception unit causes the probe to transmit a plane wave.

  In the present invention, the probe includes a plurality of vibration elements, and causes the probe to transmit a plane wave. For example, when a plurality of vibration elements are arranged in a straight line, a plane wave is transmitted by causing the plurality of vibration elements to transmit ultrasonic waves having the same intensity at the same timing. By causing the probe to transmit a plane wave, tomographic frame data for one frame is generated by one transmission and reception of ultrasonic waves, and the frame rate is increased.

  Preferably, the propagation characteristic analysis unit associates the y-axis direction particle velocity of the living tissue with the depth direction position y and the time t of the living tissue based on the plurality of tomographic frame data. For the propagation characteristic, and the filter processing unit performs a two-dimensional fast Fourier transform on the yt distribution to express a shear wave distribution with respect to the wave number k and the angular frequency ω. A conversion unit for obtaining the kω distribution, a filter operation unit for performing a filter operation on the kω distribution, and performing an inverse transform on the two-dimensional fast Fourier transform on the kω distribution on which the filter operation has been performed. An inverse transform unit for obtaining the propagation characteristics after processing.

  The filter processing unit according to the present invention performs the filter process by calculating the kω distribution. This facilitates the computation required for the filtering process.

  Preferably, the filter operation includes an operation for reducing or removing values in the second quadrant and the fourth quadrant of the kω distribution.

  According to the present invention, each filter coefficient is set in a simply partitioned region of the second quadrant and the fourth quadrant of the kω plane. As a result, the filter operation is facilitated because the filter coefficient is determined by the relationship between the value of the kω distribution and the quadrant to which the value belongs in the filter operation.

  According to the present invention, it is possible to simplify the measurement of the elastic characteristics of a living tissue.

1 is a diagram illustrating a configuration of an ultrasonic diagnostic apparatus according to an embodiment of the present invention. It is a figure which shows several tomographic frame data notionally. It is a figure which shows notionally the relationship between n-1 particle velocity distribution and yt plane. It is a figure which shows the example of yt distribution. It is a figure which shows the example of komega distribution. It is a figure which shows the example of distribution of the filter coefficient in a komega plane. It is a figure which shows the example of yt distribution after a filter process. It is a figure explaining the process which calculates | requires propagation velocity distribution on ay axis. y = _y particle velocity on the time axis in _{j v} 0 (t), and a diagram showing the y _{= y} particle velocity on the time axis in _{j + d v d (t)} .

  FIG. 1 shows the configuration of an ultrasonic diagnostic apparatus according to an embodiment of the present invention. This ultrasonic diagnostic apparatus applies pulse vibration 16 to the probe 10 by the movement of the user's hand, and applies vibration to the subject 14 by the vibration of the probe 10 to excite shear waves in the tissue. The pulse vibration 16 applied to the probe 10 has a frequency band of 10 Hz to 100 Hz, for example. Such pulse vibration reduces the pressure immediately after the user applies pressure to the subject 14 via the probe 10 with his / her hand while holding the probe 10 in contact with the subject 14. It can be generated by giving an impact to the subject 14. In the ultrasonic diagnostic apparatus, pulse vibration 16 is applied to the subject 14, ultrasonic waves are transmitted and received by the probe 10, and the elastic modulus distribution of the living tissue is measured based on the ultrasonic waves received by the probe 10.

  The configuration and operation of the ultrasonic diagnostic apparatus will be described with reference to FIG. The probe 10 includes a plurality of vibration elements 12. The plurality of vibration elements 12 are arranged in the x-axis direction along a surface that is in contact with the subject 14. The transmission unit 20 outputs a transmission signal to each vibration element 12 so that the plane wave 18 is transmitted from the probe 10 to the subject 14 under the control of the control unit 22. Each vibration element 12 generates an ultrasonic wave according to the transmission signal output from the transmission unit 20. For example, the transmission signal output to each vibration element 12 has the same intensity and output timing, and each vibration element 12 has a wavefront parallel to the contact surface of the probe 10 by simultaneously generating ultrasonic waves of the same intensity. A plane wave 18 is generated. In addition, when the plurality of vibration elements 12 are not arranged in a straight line, the intensity of ultrasonic waves generated in each vibration element 12 and the generation of ultrasonic waves in each vibration element according to the position of each vibration element 12. The timing may be adjusted.

  The ultrasonic wave transmitted from the probe 10 is reflected in the subject 14 and received by each vibration element 12. Each vibration element 12 converts the received ultrasonic wave into a reception signal that is an electrical signal and outputs the reception signal to the reception unit 24. Under the control of the control unit 22, the reception unit 24 acquires the reception signal output from each vibration element 12, and performs processing such as amplification and quadrature detection. Accordingly, the receiving unit 24 generates reception baseband data of a plurality of channels corresponding to the plurality of vibration elements 12 and stores each reception baseband data in the reception data storage unit 26. Here, each received baseband data includes an in-phase component I and a quadrature component Q. The phase angle of the vector (I, Q) on the IQ plane represents the phase angle of the received signal.

  The phasing adder 28 phasing-adds the reception baseband data of a plurality of channels stored in the reception data storage unit 26 to generate a plurality of y-axis direction reception beam data. The plurality of y-axis direction reception beam data correspond to a plurality of reception beams that are directed in the depth direction (y-axis direction) of the subject 14 and arranged in the x-axis direction. The reception beam data in the y-axis direction includes an in-phase component and a quadrature component, similar to the reception baseband data before phasing addition. The phasing addition unit 28 outputs each y-axis direction reception beam data to the frame data generation unit 30 and the tomographic image generation unit 43. Note that such phasing addition is described in, for example, Patent Document 3 described above.

  The frame data generation unit 30 generates one tomographic frame data corresponding to one transmission / reception of an ultrasonic wave based on each y-axis direction reception beam data output from the phasing addition unit 28. The control unit 22, the transmission unit 20, the probe 10, and the reception unit 24 repeatedly perform ultrasonic transmission / reception with respect to the subject 14. The phasing addition unit 28 and the frame data generation unit 30 generate a plurality of tomographic frame data with the passage of time in response to a plurality of times of ultrasonic transmission / reception repeatedly performed with the passage of time. The frame rate is, for example, 1000 frames or more and 5000 frames or less per second. The frame data generation unit 30 outputs each tomographic frame data to the propagation characteristic analysis unit 33.

FIG. 2 conceptually shows a plurality of tomographic frame data generated by the frame data generation unit 30. In this figure is shown between the time t ₀ from the time _{t 0 + (n-1)} · δ, an example in which n pieces of tomographic frame data F0~Fn-1 is generated at an interval of time [delta]. Each tomographic frame data includes a plurality of y-axis direction reception beam data 48 corresponding to a plurality of reception beams arranged in the x-axis direction.

  Each tomographic frame data is associated with xy coordinates. That is, one y-axis direction received beam data 48 is associated with the x coordinate of the corresponding received beam. In addition, the y coordinate is associated with the time axis t ′ of one y-axis direction reception beam data 48. Here, if the speed of the ultrasonic wave in the living tissue is c, there is a relationship of y = c · t ′ / 2. The data of the point (x, y) in one tomographic frame data includes an in-phase component I (x, t ′) and a quadrature component Q (x, t ′). Here, t ′ = 2y / c.

  Next, a configuration and process for generating elastic image data by obtaining an elastic modulus distribution in the xy tomographic plane of the subject 14 based on a plurality of tomographic frame data will be described. The elastic image data represents an image indicating the elastic modulus distribution on the xy tomographic plane by color or the like as an elastic image. The elastic modulus distribution is obtained by calculation of the calculation unit 42 configured by the propagation characteristic analysis unit 33, the filter processing unit 37, and the elastic characteristic analysis unit 38.

  The velocity distribution calculation unit 31 and the yt distribution calculation unit 32 constitute a propagation characteristic analysis unit 33 in which the y-axis direction component of the velocity of the biological tissue particle is associated with the depth direction position y and the time t of the biological tissue. The yt distribution is obtained as a propagation characteristic.

The velocity distribution calculation unit 31 obtains the phase difference Δφ of the vibration of the biological tissue particle corresponding to each point on the xy tomographic plane with respect to the two tomographic frame data acquired continuously before and after the time. In the example shown in FIG. 2, these two tomographic frame data are acquired at time t = t ₀ + i · δ and at time t = t ₀ + (i + 1) · δ. The tomographic frame data Fi + 1. Here, i is an integer from 0 to n-1. The phase difference Δφ is obtained based on the following (Equation 1) using the in-phase component and the quadrature component of the y-axis direction received beam data 48 at each point.

  Here, I1 and Q1 are an in-phase component and a quadrature component corresponding to the point (x, y) in the tomographic frame data acquired previously. I2 and Q2 are an in-phase component and a quadrature component corresponding to the point (x, y) in the tomographic frame data acquired later. (Expression 1) represents an angle formed by two vectors (I1, Q1) and (I2, Q2) on the IQ plane. According to such processing, the velocity distribution calculation unit 31 obtains the phase difference Δφ for the vibration of the biological tissue particle corresponding to each point on the xy tomographic plane.

  The velocity distribution calculation unit 31 obtains the y-axis direction component v of the velocity of the biological tissue particle at each point on the xy tomographic plane based on the following (Expression 2). Hereinafter, the y-axis direction component v of the velocity of the biological tissue particles is simply referred to as the particle velocity v.

c is the speed of the ultrasonic wave in the living tissue, and ω ₀ is the angular frequency of the ultrasonic wave transmitted and received by the probe 10. Such process, speed distribution calculating unit 31 calculates the distribution in the xy tomographic plane of the particle velocity relative to the tomographic frame data F0 and F1, which is the particle velocity distribution at the time t = t _0. Similarly, the particle velocity distribution is obtained for the tomographic frame data F1 and F2, and this is used as the particle velocity distribution at time t = t ₀ + δ, and the particle velocity distribution is obtained for the tomographic frame data F2 and F3, and this is obtained as time. Let the particle velocity distribution be t = t ₀ + 2δ. That is, the velocity distribution calculation unit 31 obtains a particle velocity distribution for the tomographic frame data Fi and Fi + 1, and sets this as the particle velocity distribution at time t = t ₀ + i · δ. In this way, the velocity distribution calculation unit 31 obtains n−1 particle velocity distributions for the time t ₀ to the time t ₀ + (n−2) · δ. The velocity distribution calculation unit 31 may obtain a particle velocity distribution for the tomographic frame data Fi and Fi + 1, and may use this as the particle velocity distribution at time t = t ₀ + (i + 1) · δ.

The yt distribution calculation unit 32 obtains an yt distribution for each of a plurality of x coordinate values corresponding to the positions of the plurality of reception beams based on the n−1 particle velocity distributions. The yt distribution is a distribution in which the particle velocity is associated with the position y in the depth direction of the living tissue and the time t. FIG. 3 conceptually shows the relationship between the n−1 particle velocity distribution and the yt plane 50 from which the yt distribution is obtained. In FIG. 3, n-1 particle velocity distributions are indicated by velocity distribution planes V0 to Vn-2. Each point (x, y) on the velocity distribution plane is associated with the particle velocity v (x, y) at that point. Here, the yt distribution for the x coordinate value x _j is formed by the particle velocity at each point on each intersection line 52 between the yt plane 50 represented by x = x _j and the velocity distribution planes V0 to Vn-2. Is done.

  FIG. 4 shows an example of the yt distribution for one x-coordinate value. The horizontal axis indicates the depth direction position (y coordinate value) of the living tissue, and the vertical axis indicates time t. This figure shows that the thinner the fill, the greater the particle velocity. In this yt distribution, a traveling wave component 54 that moves in the deep direction of the living tissue appears as time passes. Further, a reflected wave component 56 that moves in a shallow direction of the living tissue (y-axis negative direction, that is, a direction toward the probe 10) as time passes is also recognized.

  The yt distribution calculation unit 32 obtains the yt distribution for each of all the x coordinate values in which the reception beam exists, and outputs each yt distribution to the filter processing unit 37.

  The filter processing unit 37 includes a conversion unit 34, a filter calculation unit 35, and an inverse conversion unit 36, and reduces or removes the reflected wave component from each yt distribution by the following processing. That is, the conversion unit 34 performs a two-dimensional fast Fourier transform process described in Non-Patent Document 1 on the yt distribution to obtain a kω distribution. Here, the kω distribution is a distribution in which the intensity of the shear wave is associated with the wave number k and the angular frequency ω in the y-axis direction. The wave number is the amount of phase rotation per unit distance in the y-axis direction, and is also referred to as a propagation constant.

  FIG. 5 shows an example of the kω distribution. The horizontal axis ω indicates the angular frequency ω of the shear wave, and the vertical axis indicates the wave number k of the shear wave. This kω distribution indicates that the thinner the fill is, the larger the component of the region is. The first quadrant and the third quadrant in the kω distribution show the distribution of traveling wave components having a positive phase velocity ω / k, and the second and fourth quadrants in the kω distribution have a negative phase velocity ω / k. The distribution of reflected wave components is shown. In the example shown in FIG. 5, the traveling wave components in the first and third quadrants are dominant, but the reflected wave components in the second and fourth quadrants are also recognized.

  After the kω distribution is obtained, the filter calculation unit 35 performs a filter calculation that reduces or replaces the distribution in the second quadrant and the fourth quadrant of the kω distribution with zero. That is, in the filter operation, the value of the second quadrant where k> 0 and ω <0 and the value of the fourth quadrant where k <0 and ω> 0 are multiplied by a filter coefficient of 0 or more and less than 1. Then, the value of the first quadrant where k> 0 and ω> 0 and the value of the third quadrant where k <0 and ω <0 are multiplied by 1 as a filter coefficient. FIG. 6 illustrates the filter coefficient distribution on the kω plane. In this figure, the filter coefficients of the first quadrant and the third quadrant are set to 1, and the filter coefficients of the second quadrant and the fourth quadrant are set to 0.

  The inverse transform unit 36 performs an inverse transform process on the two-dimensional fast Fourier transform process on the kω distribution subjected to the filter operation, generates a yt distribution after the filter process, and outputs the generated yt distribution to the elastic characteristic analysis unit 38. .

  Through such processing, the filter processing unit 37 performs filter processing on each yt distribution obtained for each of the x-coordinate values where the reception beam exists, and converts each yt distribution after the filter processing into an elastic characteristic. The data is output to the analysis unit 38.

  FIG. 7 shows an example of the yt distribution after filtering obtained for a certain x coordinate value. In this yt distribution, the reflected wave component 56 as seen in the yt distribution shown in FIG. 4 is removed.

The elastic characteristic analysis unit 38 performs a shear wave propagation velocity in the y-axis direction at each point on the y-axis on the xy tomographic plane for each x-coordinate value in which the received beam exists by the following process ( y-axis propagation velocity distribution). FIG. 8 shows an yt distribution for explaining a process for obtaining a propagation velocity distribution on the y-axis for one x-coordinate value. The elastic characteristic analysis unit 38 extracts the particle velocity v ₀ (t) = v (y _j , t) on the time axis at y = y _j . Furthermore, the elastic characteristic analysis unit 38 extracts the particle velocity v _d (t) = v (y _j + d, t) on the time axis at y = y _j + d that is a distance d away from it in the positive y-axis direction. . FIG. 9A shows the particle velocity v ₀ (t). FIG. 9B shows the particle velocity v _d (t).

The elastic characteristic analysis unit 38 obtains a correlation function R (τ) between the particle velocity v ₀ (t) and the particle velocity v _d (t + τ) according to the following (Equation 3).

The correlation function R (τ) represents the degree of approximation between the waveform of the particle velocity v ₀ (t) and the waveform obtained by translating the waveform of the particle velocity v _d (t) by τ in the negative direction of the t-axis. Elastic characteristic analyzer 38 obtains the correlation function R (tau) for the tau while changing the tau, the value of tau when the correlation function R (tau) is maximum, y = y _j from y = y _j It is assumed that the propagation time T reaches + d. The elastic characteristic analysis unit 38 calculates C _S = d / T and sets C _S as the shear wave propagation velocity in the y-axis direction at y = y _j (or y _j + d).

The elastic characteristic analysis unit 38 changes the y coordinate value y _j over the range of the living tissue, and performs such processing on each point on the y axis in the xy tomographic plane. As a result, the elastic characteristic analyzer 38 obtains one propagation velocity distribution on the y-axis for one x-coordinate value.

  The elastic characteristic analysis unit 38 obtains the propagation velocity distribution on the y axis for each of the x coordinate values where the reception beam exists, and obtains the shear wave velocity distribution on the xy tomographic plane. The shear wave velocity distribution thus obtained is a distribution in which the propagation velocity of the shear wave in the y-axis direction is associated with each point on the xy tomographic plane.

  That is, the propagation velocity distribution on one y-axis is obtained from one yt plane 50 shown in FIG. 3, and the propagation velocity on the y-axis obtained for each of all x-coordinate values in which the received beam exists. A shear wave velocity distribution in the xy fault plane is formed by the set of distributions.

The elastic characteristic analyzer 38 obtains the elastic modulus distribution in the xy fault plane based on the shear wave velocity distribution in the xy fault plane. This process uses a shear wave propagation velocity C _S of each point in the xy tomographic plane is performed by determining the modulus of elasticity E based on the following equation (4).

Here, ρ is the density of living tissue, and in the case of soft tissue, it is approximately 1000 kg / m ³ . The elastic characteristic analysis unit 38 outputs the elastic modulus distribution on the xy tomographic plane to the elastic image generation unit 40. The elastic image generation unit 40 generates elastic image data based on the elastic modulus distribution and outputs the elastic image data to the image composition unit 44. The elastic image indicated by the elastic image data represents, for example, a region having a large elastic modulus in blue, a region having a small elastic modulus in red, and a region in which the elastic modulus is an intermediate value thereof in green or yellow. The elastic modulus may be expressed by a paint pattern, a numerical value, a three-dimensional graph, or the like in addition to the color.

  Next, processing in which the tomographic image generation unit 43 generates tomographic image data on the xy tomographic plane based on each y-axis direction reception beam data output from the phasing addition unit 28 will be described. The tomographic image generation unit 43 generates tomographic image data on the xy tomographic plane based on each y-axis direction reception beam data corresponding to a plurality of reception beams arranged in the x-axis direction, and outputs the tomographic image data to the image composition unit 44. The tomographic image generation unit 43 generates tomographic image data for one image corresponding to one transmission / reception of ultrasonic waves. The tomographic image generation unit 43 generates tomographic frame data for a plurality of images corresponding to a plurality of times of ultrasonic transmission / reception repeatedly performed with time, and outputs the generated tomographic frame data to the image synthesis unit 44.

  The image composition unit 44 is based on the tomographic image data output from the tomographic image generation unit 43 and the elastic image data output from the elastic image generation unit 40. Elastic image data is generated and output to the display unit 46. The display unit 46 displays an image based on the tomographic / elastic image data. Thus, the user can grasp the elastic modulus distribution together with the tomographic image, and can diagnose cancer, arteriosclerosis, liver fibrosis, cirrhosis, and the like.

  In the above description, the example in which the plane wave 18 having the wave front parallel to the contact surface of the probe 10 is generated by simultaneously generating the ultrasonic waves of the same intensity in the respective vibration elements 12 has been described. In addition to such a configuration, the control unit 22 controls the transmission unit 20 and the reception unit 24 to form one or a plurality of ultrasonic beams in the probe 10, and scans this ultrasonic beam on the xy tomographic plane. Also good. In this case, a transmission signal whose delay time is adjusted so that an ultrasonic beam is formed is input to each vibration element 12. Further, every time the ultrasonic beam scans the xy tomographic plane once, one tomographic frame data is generated by the frame data generating unit 30, and one image of tomographic image data is generated by the tomographic image generating unit 43.

  In the ultrasonic diagnostic apparatus according to the present embodiment, pulse vibration is given to the probe by the movement of the user's hand, and the subject is vibrated by the vibration of the probe to excite a shear wave in the living tissue. Accordingly, since a mechanism for generating vibration is not required, the configuration of the ultrasonic diagnostic apparatus is simplified and measurement is facilitated. The frequency component of the shear wave can be easily adjusted by user control. Moreover, the energy of ultrasonic waves may be smaller than that in the case where shear waves are generated in a living tissue by acoustic radiation pressure. This facilitates measurement of a part having a large reflection coefficient for ultrasonic waves.

  Furthermore, since the reflected wave component of the shear wave is reduced or removed by the filter processing unit, the measurement accuracy of the elastic modulus distribution is improved. This process is simple because the kω distribution is multiplied by a filter coefficient. Further, each filter coefficient is set in a simply partitioned region of the second quadrant and the fourth quadrant of the kω plane. As a result, in the filtering process, the filter coefficient is determined by the relationship between the value of the kω distribution and the quadrant to which the value belongs, so that the filter operation is facilitated.

10 probe, 12 vibration element, 14 subject, 16 pulse vibration, 18 plane wave, 20 transmission unit, 22 control unit, 24 reception unit, 26 reception data storage unit, 28 phasing addition unit, 30 frame data generation unit, 31 speed Distribution calculation unit, 32 yt distribution calculation unit, 33 propagation characteristic analysis unit, 34 conversion unit, 35 filter calculation unit, 36 inverse conversion unit, 37 filter processing unit, 38 elastic characteristic analysis unit, 40 elastic image generation unit, 42 calculation unit , 43 Tomographic image generation unit, 44 Image composition unit, 46 Display unit, 48 Received beam data, 50 yt plane, 52 yt plane and velocity distribution plane intersection line, 54 traveling wave component, 56 reflected wave component.

Claims (4)

A probe that vibrates biological tissue by the movement of the user's hand;
A transmitting / receiving unit for transmitting and receiving ultrasonic waves to the probe;
A frame data generation unit for generating tomographic frame data of the living tissue based on the reception data output from the transmission / reception unit;
A calculation unit that obtains an elastic characteristic in a tomographic plane of the living tissue based on a plurality of tomographic frame data generated over time by the frame data generation unit,
The computing unit is
Based on the plurality of fault frame data, a propagation characteristic analysis unit for obtaining a propagation characteristic of shear wave,
A filter processing unit that performs a filtering process to remove or reduce a reflected wave component of the shear wave with respect to the propagation characteristics;
Based on the propagation characteristics after the filter processing, an elastic characteristic analysis unit for obtaining the elastic characteristics;
An ultrasonic diagnostic apparatus comprising: The ultrasonic diagnostic apparatus according to claim 1,
The probe is
It has a plurality of vibration elements arranged in a line,
The transceiver unit is
An ultrasonic diagnostic apparatus, wherein the probe transmits a plane wave. The ultrasonic diagnostic apparatus according to claim 1 or 2,
The propagation characteristic analyzer is
Yt distribution calculation for obtaining, as the propagation characteristics, an yt distribution in which the y-axis direction particle velocity of the living tissue is associated with the depth direction position y and the time t of the living tissue based on the plurality of tomographic frame data Part
The filter processing unit
A conversion unit for performing a two-dimensional fast Fourier transform on the yt distribution to obtain a kω distribution representing a shear wave distribution with respect to the wave number k and the angular frequency ω;
A filter operation unit that performs a filter operation on the kω distribution;
An inverse transform unit that performs an inverse transform on the two-dimensional fast Fourier transform to the kω distribution on which the filter operation has been performed, and obtains the propagation characteristics after the filter processing;
An ultrasonic diagnostic apparatus comprising: The ultrasonic diagnostic apparatus according to claim 3.
The filter operation is
An ultrasonic diagnostic apparatus comprising: an operation for reducing or removing values in the second quadrant and the fourth quadrant of the kω distribution.

Images