JP4030288B2 - Ultrasonic diagnostic equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to an apparatus for measuring information related to a minute displacement of a tissue.
[0002]
[Prior art]
In the ultrasonic diagnostic apparatus, the velocity information of the blood flow in the living body is measured according to the ultrasonic Doppler method, and the velocity information is displayed as a two-dimensional blood flow image (see, for example, Japanese Patent Publication No. Sho 62-44494). On the other hand, in recent years, an ultrasonic diagnostic apparatus having a tissue Doppler measurement function is also provided. The function is to measure velocity information of a tissue (low-speed moving body) such as a myocardium in a living body according to the ultrasonic Doppler method as described above, and display the velocity information as a two-dimensional tissue image (for example, Japanese Patent Application 7-67449).
[0003]
In any of the above cases, generally, a quadrature detector that converts a received signal into a complex signal, an autocorrelator that performs autocorrelation calculation of the complex signal, and a speed that calculates the speed from the autocorrelation calculation result An arithmetic unit is used. Then, a plurality of transmissions / receptions are executed for the same beam direction (a plurality of ultrasonic beams are formed), and the complex signal obtained by the previous transmission / reception is temporarily stored in the line memory and read from there. Correlation is performed between the complex signal and the complex signal obtained by subsequent transmission and reception (that is, between the beams).
[0004]
[Problems to be solved by the invention]
By the way, for example, when an artery (relatively thick artery) in an organ pulsates, it becomes a force generation source, and the generated force propagates to surrounding tissues. At this time, when viewed microscopically, displacement (distortion) occurs in the tissue at each position. Different physical properties such as tissue hardness (elastic modulus), composition, structure, etc. result in different displacements in the tissue. Similarly, as seen in palpation, for example, when an external force is applied from outside the body, the force propagates through the tissue, and the tissue is displaced according to the physical properties of the tissue as described above. Palpation is a sensory test for detecting the presence of a tumor and the state of a tissue by sensing the change in state when such a tissue is subjected to force with the sense of a fingertip.
[0005]
However, the displacement of the tissue as described above is extremely small. For example, the displacement speed is several mm / s or less. The conventional ultrasonic diagnostic apparatus has no technical idea for two-dimensional display of such extremely low-speed motion information.
[0006]
The present invention has been made in view of the above-described conventional problems, and an object thereof is to provide an ultrasonic diagnostic apparatus capable of imaging a physical property of a tissue.
[0007]
Another object of the present invention is to provide an ultrasonic diagnostic apparatus capable of two-dimensionally displaying information on a minute displacement of a tissue.
[0008]
Another object of the present invention is to provide an ultrasonic diagnostic apparatus capable of visualizing a microscopic change of a tissue caused by a tissue motion inside a living body.
[0009]
Another object of the present invention is to provide an ultrasonic diagnostic apparatus capable of visualizing a microscopic change of a tissue due to an external force.
[0010]
[Means for Solving the Problems]
  Preferably, an ultrasonic diagnostic device isA transmission / reception unit that sequentially forms a scanning plane by repeatedly scanning an ultrasonic beam and outputs a reception signal; and a complex signal conversion unit that converts the reception signal into a complex signal composed of a real part signal and an imaginary part signal; A real part memory for storing the real part signal for at least one frame, and an imaginary part memory for storing the imaginary part signal for at least one frame. From the inter-frame correlation calculation means for performing inter-frame correlation calculation using the real part signal and the imaginary part signal for each sample point, and outputting the inter-frame correlation calculation result for each sample point, Information calculating means for calculating information related to the minute displacement of the tissue in the direction of the ultrasonic beam.Mu
[0011]
According to the above configuration, correlation calculation of complex signals is performed between frames, and information related to a minute displacement of tissue is obtained from the calculation result. Since the correlation calculation is performed between frames, the correlation calculation interval follows the frame rate, and it is possible to detect a very low-speed displacement that cannot be detected by a conventional apparatus.
[0012]
Here, the tissue is a tissue of a human body or an animal other than the human body, and usually a measurement is performed on a soft tissue, but a hard tissue (such as a bone) may be a measurement target. The complex signal conversion means is preferably means for performing quadrature detection or signal processing corresponding thereto. As the inter-frame correlation calculation means, for example, in the configuration of a known autocorrelation calculation circuit, the storage unit is changed from line to frame. It can be realized by changing. The information related to the minute displacement of the tissue is the speed and acceleration of the displacement, and other information may be the strain speed, strain acceleration, and stress of the tissue.
[0013]
According to the present invention, it is possible to measure a minute displacement caused by internal pulsation and a minute displacement caused by an external force that cannot be sensed by a conventional apparatus, and can provide useful information for diagnosis.
[0014]
Preferably, the information calculation means includes a speed calculator that calculates a minute displacement speed of the tissue from the inter-frame correlation calculation result as information related to the minute displacement of the tissue. For example, speed information is obtained by calculating an arctangent between a real part and an imaginary part in an inter-frame autocorrelation calculation result obtained as a complex signal.
[0015]
Preferably, the information calculation means includes an acceleration calculator that calculates a minute displacement acceleration of the tissue from the inter-frame correlation calculation result as information related to the minute displacement of the tissue. For example, acceleration information can be obtained by further performing a correlation calculation between frames with respect to a minute displacement speed. In the speed calculation and the acceleration calculation, the calculation frame intervals may be the same or different.
[0016]
Preferably, the information calculation means includes a strain rate calculator for calculating a minute strain rate of the tissue from the inter-frame correlation calculation result as information relating to the minute displacement of the tissue. The minute distortion speed is obtained, for example, by calculating a spatial gradient for the inter-frame autocorrelation result.
[0017]
Preferably, the information calculation means includes a strain acceleration calculator for calculating a minute strain acceleration of the tissue from the inter-frame correlation calculation result as information relating to the minute displacement of the tissue. The slight strain acceleration is obtained, for example, by calculating a spatial gradient with respect to the inter-frame autocorrelation result.
[0018]
Preferably, the inter-frame correlation calculation means executes an inter-frame correlation calculation between two temporally adjacent frames. The region of interest may be set manually or automatically in the frame, and the inter-frame correlation calculation may be performed within the region of interest.
[0019]
Preferably, the real part memory stores the real part signal for a plurality of frames, the imaginary part memory stores the imaginary part signal for a plurality of frames, and the inter-frame correlation calculating means includes n (however, , N is an integer of 1 or more) A frame correlation calculation is performed between two frames with a frame in between.
[0020]
Preferably, it includes means for variably setting a time interval between two frames for performing the inter-frame correlation calculation. According to the variable setting of the time interval, it is possible to freely adjust the measurement range of the minute displacement.
[0021]
Preferably, the wave transmitting / receiving unit transmits a broadband ultrasonic wave used for forming a tomographic image, and information related to a minute displacement of the tissue is calculated using a reception signal obtained by the transmission of the broadband ultrasonic wave. Is done. In conventional Doppler measurement, narrow-band ultrasonic waves are transmitted. However, in the present invention, wide-band ultrasonic waves used in normal B-mode measurement and the like can be used without necessarily using them.
[0022]
Preferably, it includes an averaging means for performing spatial averaging processing within a frame on the inter-frame correlation calculation result, and the information calculation means uses the inter-frame correlation calculation result that has undergone the spatial averaging process. Information related to the minute displacement of the tissue is calculated. Here, the spatial averaging process is performed for each of the depth direction and the scanning direction of the ultrasonic beam, or both.
[0023]
Desirably, a displacement display image forming means for forming a displacement display image by two-dimensionally mapping information related to the minute displacement of the tissue is included. The displacement display image is a two-dimensional representation of information such as displacement speed, displacement acceleration, strain speed, and strain acceleration, and can spatially recognize minute displacements of tissue.
[0024]
Preferably, a tomographic image forming unit that forms a tomographic image based on the received signal, and an image combining unit that combines the displacement display image and the tomographic image to form a combined image. According to this configuration, it is possible to observe the distribution of minute displacement of the tissue and its temporal variation in relation to the tomographic image.
[0025]
Preferably, the tomographic image is a black and white image, and the displacement display image is a color image. According to this configuration, it is possible to observe the displacement display image with high visibility using the tomographic image as a background.
[0026]
  Preferably, an ultrasonic diagnostic device isIn an ultrasonic diagnostic apparatus for two-dimensionally displaying information on a minute displacement of a tissue due to a force generated inside the living body or a force applied from outside the living body, the scanning surface is scanned by repeatedly scanning the tissue with an ultrasonic beam. Means for sequentially forming and outputting a received signal; means for converting the received signal into a complex signal; and performing a correlation operation of the complex signal for each sample point between frames, and performing inter-frame correlation for each sample point. Means for outputting a calculation result; means for calculating information on a minute displacement of the tissue in the ultrasonic beam direction for each sample point from the correlation calculation result for each sample point; and a tissue in the ultrasonic beam direction for each sample point Means for forming a displacement display image by two-dimensionally mapping information on minute displacements ofMu
[0027]
  According to the inter-frame correlation calculation described above, a change in signal phase can be detected, and a velocity that is, for example, about two orders of magnitude smaller than the normal blood flow velocity can be detected. Note that the correlation calculation between frames can be used for measurements other than the measurement of the minute strain of the tissue, and even in that case, the measurement result or the calculation result can be two-dimensionally mapped as described above. .
  According to the present invention, a scanning surface is sequentially formed by repeatedly scanning an ultrasonic beam, and a transmission / reception unit that outputs a reception signal, and the reception signal from the first real part signal and the first imaginary part signal. A complex signal converting means for converting the first complex signal, a first real part memory for storing at least one frame of the first real part signal, and at least one frame of the first imaginary part signal. A first frame using a first real part signal and a first imaginary part signal for each sample point between two temporally different frames. First inter-frame correlation that performs inter-correlation calculation and outputs a second complex signal consisting of a second real part signal and a second imaginary part signal as a first inter-frame correlation calculation result for each sample point Computing means; and the second A velocity calculator that calculates a minute displacement velocity of the tissue in the ultrasonic beam direction from the complex signal, a second real part memory that stores at least one frame of the second real part signal, and the second imaginary number A second imaginary part memory for storing at least one frame part signal, and a second real part signal and a second imaginary part signal for each sample point between two temporally different frames. The second inter-frame correlation calculation using is performed, and the third complex signal composed of the third real part signal and the third imaginary part signal is output as the second inter-frame correlation calculation result for each sample point. Second inter-frame correlation calculating means, and an acceleration calculator for calculating a minute displacement acceleration of the tissue in the ultrasonic beam direction from the third complex signal.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.
[0029]
FIG. 1 shows a preferred embodiment of an ultrasonic diagnostic apparatus according to the present invention, and FIG. 1 is a block diagram showing the overall configuration thereof. This ultrasonic diagnostic apparatus has a function of imaging a minute displacement of a tissue in a living body.
[0030]
For example, when an artery pulsates in the liver, distortion caused by the pulsation propagates to the surrounding tissue. According to the ultrasonic diagnostic apparatus according to the present embodiment, such a slight displacement or distortion is two-dimensional. It can be displayed as an image. Further, the present invention is not limited to such arterial pulsation, and it is also possible to display, as a two-dimensional image, a minute displacement or a slight distortion of a tissue due to a force exerted from outside the living body.
[0031]
In FIG. 1, a probe 10 is an ultrasonic probe that is used in contact with the surface of a living body or is inserted into a body cavity. The probe 10 has an array transducer composed of a plurality of vibration elements. An ultrasonic beam is scanned using this array transducer. As a result, the scanning plane is sequentially formed. Examples of the ultrasonic beam scanning method include electronic linear scanning and electronic sector scanning.
[0032]
In this embodiment, broadband ultrasonic waves used when forming a two-dimensional tomographic image (B-mode image) are transmitted and received. The center frequency of the ultrasonic wave is, for example, 3.5 MHz, and the band thereof is, for example, 2 MHz. Of course, the present invention is not limited to these values.
[0033]
The transmission circuit 12 functions as a transmission beam former, and supplies transmission signals to a plurality of vibration elements constituting the array transducer. The reception circuit 14 functions as a reception beam former, and executes a phasing addition process on reception signals from a plurality of vibration elements constituting the array transducer, thereby outputting a reception signal after phasing addition.
[0034]
The control unit 16 functions as a transmission / reception control unit and controls the operation of each component in the present apparatus. An input device 17 composed of a keyboard, a trackball, or the like is connected to the control unit 16, and the user can make various settings using the input device 17. In the present embodiment, the input unit 17 can be used to specify a frame interval in correlation calculation described later.
[0035]
In the embodiment shown in FIG. 1, the reception signal output from the reception circuit 14 is input to the A / D converter 18, and the reception signal is converted from an analog signal to a digital signal by the A / D converter 18. The received signal converted into the digital signal is input to the quadrature detector 20. However, the A / D converter 18 may be provided after the quadrature detector 20 or may be provided inside the receiving circuit 14. Alternatively, a circuit configuration that simultaneously performs quadrature detection and digital sampling may be employed.
[0036]
The quadrature detector 20 includes two mixers in the present embodiment, and each mixer performs quadrature detection on the received signal by mixing a predetermined reference signal with the received signal. A complex signal is generated by this quadrature detection. Here, the complex signal is represented by the symbol z1 in FIG. 1, and the complex signal z1 is composed of a real part signal x1 and an imaginary part signal y1. The real part signal x1 and the imaginary part signal y1 are stored in the frame memories 23A and 23B, respectively. The frame memories 23A and 23B have a storage capacity for one frame. Here, the frame corresponds to one scanning of the ultrasonic beam, and specifically corresponds to a so-called scanning plane. However, the frame memories 23A and 23B may be provided as necessary.
[0037]
The real part signal x1 and the imaginary part signal y1 output from the frame memories 23A and 23B are output to the tomographic image forming unit 22. Specifically, these signals are subjected to predetermined amplification processing by the amplifiers 24A and 24B and then input to the scan converters 26A and 26B, respectively. Here, the scan converters 26A and 26B are circuits that perform coordinate conversion from the transmission / reception coordinate system to the display coordinate system, and are configured by a known DSC (digital scan converter) or the like.
[0038]
In the configuration example shown in FIG. 1, the scan converters 26 </ b> A and 26 </ b> B are provided in the preceding stage of the amplitude calculator 30, but the invention is naturally not limited to this, and the scan conversion may be performed in another signal processing process. For example, scan conversion may be performed after the amplitude calculation. The same applies to scan converters 48A and 48B and scan converters 58A and 58B described later.
[0039]
The amplitude calculator 30 is a circuit that calculates the amplitude of the complex signal by executing an absolute value calculation on the real part signal and the imaginary part signal output from the scan converters 26A and 26B. For example, the amplitude can be calculated by adding the square of the real part signal and the square of the imaginary part signal and calculating the square root of the addition result. Thereby, each data constituting the tomographic image is calculated, and the data is output to the combining unit 62. Incidentally, in forming a tomographic image, the compression processing for each data may be performed by the above-described amplifiers 24A and 24B.
[0040]
Next, the speed calculation unit 32 and the acceleration calculation unit 34 will be described.
[0041]
  The correlation calculator 36 receives the complex signal z1 output from the frame memories 23A and 23B. The correlation calculator 36 has a circuit configuration similar to that of the autocorrelator described in Japanese Patent Publication No. Sho 62-44494 described in the conventional example, and a complex signal is obtained for each sample point between frames. Performs conjugate product operation, which results in correlation(That is, tissue motion information in the direction of the ultrasonic beam)Is output.
[0042]
Specifically, the real part signal x1 is input to the memory 38A, and the imaginary part signal y1 is input to the memory 38B. Each of these memories 38A and 38B has a storage area for one frame or more, and preferably has a storage capacity for a plurality of frames.
[0043]
These memories 38A and 38B function as a storage unit for delaying the input complex signal by a predetermined number of frames. Therefore, a complex signal z2 delayed by a predetermined number of frames is output from the memories 38A and 38B.
[0044]
In the correlation calculator 36, an autocorrelation calculation, that is, a complex conjugate product calculation, is performed between the complex signal z1 and the complex signal z2 delayed by a predetermined number of frames. For this purpose, the four multipliers 40A to 40A. 40D and two adders 42A and 42B are provided. Specifically, these circuits perform the following operations.
[0045]
x3 = x1x2 + y1y2 (1)
y3 = x2y1-x1y2 (2)
By the above calculation, a correlation calculation result between frames is obtained, which is the complex signal z3. Here, the complex signal z3 is composed of a real part signal x3 and an imaginary part signal y3. These signals are stored in the frame memories 44A and 44B, respectively. The frame memories 44A and 44B have a storage capacity for storing data for one frame, and the frame memories 44A and 44B are provided as necessary.
[0046]
The spatial averagers 46A and 46B are circuits that perform spatial averaging processing on each of the real part signal x3 and the imaginary part signal y3. The spatial averaging process corresponds to, for example, a moving average process in a frame. In this case, the moving average process may be performed along the depth direction, the moving average process may be performed along the beam scanning direction, or the moving average process may be performed in both directions. In any case, by performing such a spatial averaging process, noise can be reduced and the SN ratio can be improved.
[0047]
The scan converters 48 </ b> A and 48 </ b> B are circuits that perform coordinate conversion on each of the real part signal and the imaginary part signal, and the real part signal and the imaginary part signal after the coordinate conversion are input to the speed calculator 50. The speed calculator 50 is a circuit for calculating speed information by calculating an arctangent, that is, a declination, using a real part signal and an imaginary part signal. The obtained speed information is output to the synthesizing unit 62 as a speed image.
[0048]
In the present embodiment, an acceleration calculation unit 34 is provided in addition to the speed calculation unit 32 described above. This will be described below.
[0049]
The correlation calculator 52 has the same circuit configuration as the correlation calculator 36 described above. Specifically, it has two memories, four multipliers, and two adders, and a complex signal z3 output from the frame memories 44A and 44B and a complex signal obtained by delaying it by a predetermined number of frames. This is a circuit for obtaining a complex signal z5 as a correlation calculation result by executing a correlation calculation with z4. The complex signal z5 is composed of a real part signal x5 and an imaginary part signal y5. That is, acceleration information is obtained by further performing a correlation calculation between the two correlation calculation results.
[0050]
The real part signal x5 and the imaginary part signal y5 are temporarily stored in the frame memories 54A and 54B, respectively, and then the signals read from the respective memories are input to the space averagers 56A and 56B. These spatial averagers 56A and 56B have the same circuit configuration as the spatial averagers 46A and 46B described above. The complex signals output from the space averagers 56A and 56B are input to the scan converters 58A and 58B, where the coordinate conversion is performed, and the real part signal and the imaginary part signal after the coordinate conversion are converted into the acceleration calculator. The acceleration is obtained by executing an arc tangent calculation using a real part and an imaginary part in the acceleration calculator 60.
[0051]
Here, the scan converters 58A and 58B have the same configuration as the scan converters 48A and 48B. Information representing the acceleration output from the acceleration calculator 60 is output to the synthesizing unit 62 as constituting an acceleration image.
[0052]
The synthesizer 62 forms a tomographic image by two-dimensionally mapping information representing the tomographic image. Also, a velocity image is formed by two-dimensional mapping the velocity information in the same manner as described above. Further, an acceleration image is formed by two-dimensional mapping the acceleration information in the same manner as described above. Then, for example, a plurality of images selected by the user are combined and the combined image is output to the display 64.
[0053]
For example, the tomographic image may be a black and white image, the velocity image may be a color image, and the two images may be combined to form a display image that represents the velocity by color with the tomographic image as the background. This also applies to the acceleration image. For example, when displaying the speed in color, the direction approaching the probe 10 is positive, the direction away from the probe 10 is negative, and the red direction is assigned to the positive direction according to the magnitude of the speed. As for, blue brightness may be assigned in accordance with the speed, and a speed image may be displayed like a two-dimensional color Doppler image. Further, even when displaying an acceleration image, it is possible to adopt the same display method as described above. However, when displaying speed and acceleration at the same time, a green luminance is assigned to the magnitude of acceleration, so-called color mixing. It is also possible to display the speed and acceleration at the same time. Furthermore, it is possible to calculate a slight tissue distortion by calculating the velocity gradient in the frame in the configuration shown in FIG. 1, which will be described later with reference to FIG. In the configuration shown in FIG. 1, the measurement range of minute displacement can be changed by adjusting the frame interval in the correlation calculation.
[0054]
For example, the number of frames between frames may be variable from 0 to the maximum value. Of course, in that case, the storage capacity of the memories 38A and 38B and the similar memory provided in the correlation calculator 52 may be appropriately set according to the maximum value.
[0055]
FIG. 2 shows the concept of correlation calculation.
[0056]
In FIG. 2, reference numeral 200 represents a scanning plane. As described above, echo data is taken in at each sample point on the scanning plane and each echo data is converted into a complex signal. In FIG. 2, # 1 to # 5 represent numbers of sequentially formed scanning planes, X represents the ultrasonic beam direction, and Y represents the electronic scanning direction. In FIG. 2, the concept in the case where electronic linear scanning is performed is shown for explaining the invention, but the present invention is of course applicable to cases where other scanning methods such as electronic sector scanning are used.
[0057]
FIG. 2A shows a case where a correlation calculation is performed between adjacent frames (see reference numerals 201 to 204). For example, paying attention to frames # 1 and # 2, a correlation calculation is performed on the complex signals S1 and S2 at the same sample point, and velocity information, that is, information representing a minute displacement of the tissue is obtained as the correlation calculation result. In the present embodiment, as indicated by reference numerals 205 to 207, acceleration information is also calculated by performing a correlation calculation between each of the speed information calculated in time series order.
[0058]
FIG. 2B shows the concept of performing correlation calculation between non-adjacent frames, that is, how correlation calculation is performed between two frames with one or more frames in between. (See reference numerals 208 to 210).
[0059]
3 and 4 show configuration examples of the spatial averagers 46A, 46B, 56A, and 56B.
[0060]
In FIG. 3, the data memories 70 and 72 have a storage capacity for one echo data, and three echo data arranged in the ultrasonic beam direction (more precisely, a real part signal or an imaginary part signal after correlation calculation) are stored. The weighted adder 74 is input, and the weighted adder 74 performs weighted addition on a plurality of signals. Thereby, the spatial averaging process can be performed along the ultrasonic beam direction, that is, the depth direction. Here, the number of additions is arbitrary.
[0061]
In the configuration example shown in FIG. 4, the line memories 76 and 78 have a storage capacity for one ultrasonic beam, so that the weighting adder 80 has echo data (accurately) corresponding to three adjacent ultrasonic beams. Is input with a real part signal or an imaginary part signal constituting a complex signal. Then, the weighting adder 80 performs weighted addition on the input data, thereby executing a spatial averaging process in the electronic scanning direction. Again, the number of additions is arbitrary. Of course, the spatial averaging processing may be performed by combining the configuration shown in FIG. 3 and the configuration shown in FIG. 4, or another configuration may be adopted. The configuration shown in FIGS. 3 and 4 is merely an example of a spatial averager. Incidentally, in the configuration shown in FIG. 1, the spatial averaging process is performed in the subsequent stage of the correlation calculator, but this spatial averaging process can also be performed at other positions, for example, speed calculation and acceleration calculation. Such processing may be performed later.
[0062]
FIG. 5 shows an example of the synthesis process in the synthesis unit 62. The tomographic image 100 is configured as a black and white image, and the velocity image 102 is configured as a color image. Then, the synthesized image 104 is synthesized by synthesizing the velocity image 102 on the tomographic image 100. This composite image 104 is displayed in real time, and corresponds to, for example, a color representation of the propagation of strain generated from an artery in the liver on a tomographic image of the liver.
[0063]
FIG. 6 shows a modified example in which a strain rate calculator 82 is provided. The strain speed calculator 82 is a circuit that calculates a speed gradient in the frame, and receives speed information from the speed calculator 50. Then, by calculating the velocity gradient along the ultrasonic beam direction, it is possible to calculate the strain magnitude distribution in that direction. The synthesizer 62 forms a distortion image by two-dimensionally mapping the magnitude of the distortion, and such a distortion image can be displayed alone or combined with a tomographic image.
[0064]
In the configuration example shown in FIG. 6, a strain acceleration calculator 84 is further provided. The strain acceleration calculator 84 is a circuit that calculates the gradient of acceleration in the frame, and the acceleration information from the acceleration calculator 60 is input. Then, by calculating the gradient of acceleration spatially, not temporally, along the ultrasonic beam direction, the strain acceleration in that direction can be calculated. In the synthesizing unit 62, an image in which such strain acceleration is two-dimensionally mapped is constructed, and is displayed alone or synthesized. When calculating the strain rate and strain acceleration, the above spatial averaging may not be performed, or the degree thereof may be weakened.
[0065]
As described above, according to the above embodiment, there is an advantage that a minute displacement of a tissue can be visualized and a new image can be provided for disease diagnosis.
[0066]
【The invention's effect】
As described above, according to the present invention, the physical properties of tissue can be imaged. Further, according to the present invention, a minute displacement of a tissue can be displayed two-dimensionally.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a preferred embodiment of an ultrasonic diagnostic apparatus according to the present invention.
FIG. 2 is a diagram showing a concept of correlation calculation between frames.
FIG. 3 is a diagram illustrating a configuration example of a spatial averager.
FIG. 4 is a diagram showing another configuration example of the spatial averager.
FIG. 5 is a diagram illustrating a concept of image composition.
FIG. 6 is a diagram illustrating a configuration example in which a strain rate calculator and a strain acceleration calculator are provided.
[Explanation of symbols]
10 probe, 12 transmission circuit, 14 reception circuit, 20 orthogonal detector, 22 tomographic image forming unit, 32 speed calculation unit, 34 acceleration calculation unit, 36 correlation calculator, 50 speed calculator, 52 correlation calculator, 60 acceleration calculation Device, 62 composition unit, 64 display device.

Claims (1)

A transmitting / receiving means for sequentially forming a scanning surface by repeatedly scanning an ultrasonic beam and outputting a reception signal;
Complex signal converting means for converting the received signal into a first complex signal composed of a first real part signal and a first imaginary part signal;
A first real part memory for storing the first real part signal for at least one frame; and a first imaginary part memory for storing the first imaginary part signal for at least one frame; A first inter-frame correlation calculation using the first real part signal and the first imaginary part signal is performed for each sample point between two temporally different frames, and the first inter-frame correlation operation is performed for each sample point. First inter-frame correlation calculating means for outputting a second complex signal composed of a second real part signal and a second imaginary part signal as an inter-frame correlation calculation result;
A velocity calculator for calculating a minute displacement velocity of the tissue in the ultrasonic beam direction from the second complex signal;
A second real part memory for storing the second real part signal for at least one frame; and a second imaginary part memory for storing the second imaginary part signal for at least one frame; A second inter-frame correlation operation using the second real part signal and the second imaginary part signal is executed for each sample point between two temporally different frames, and the second inter-frame correlation operation is performed for each sample point. Second inter-frame correlation calculating means for outputting a third complex signal composed of a third real part signal and a third imaginary part signal as a result of inter-frame correlation calculation;
An acceleration calculator for calculating a minute displacement acceleration of the tissue in the ultrasonic beam direction from the third complex signal;
An ultrasonic diagnostic apparatus comprising:

Images