Method for displaying the mobility of body tissues, and display device.

Abstract

The present invention provides a shear wave image processing method and processing apparatus that enable the comparison and accurate evaluation of changes in hardness at various depths in a loosely connected tissue sandwiched between hard layers. [Solution] The system involves bringing a vibrator into contact with the body surface to cause sinusoidal vibration of fascial tissue, and simultaneously bringing an ultrasonic probe into contact with the body surface from nearby to transmit and receive ultrasonic signals, thereby acquiring shear wave images and displaying the state of loose connective tissue in the body tissue on a display device. The system includes the steps of: acquiring shear velocity images at each depth included in the predetermined depth range by transmitting and receiving ultrasonic signals with the ultrasonic probe; detecting "multiple peaks" of shear wave velocity values ​​in the image region by comparing the acquired shear velocity images at each depth; calculating the shear strain between the multiple peaks based on the depth of each detected peak; and adding a mobility indicator to the shear velocity image according to the calculated shear strain value.

Description

Technical Field

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[0001] The present invention relates to a method and apparatus for displaying the mobility of a living body tissue that visualizes the hardness of a body tissue (including muscle, tendon, organs (including liver, breast, thyroid, etc.)) of a living organism (human body or animal) using ultrasonic waves. Particularly, the target location is regarded as loose connective tissue (intermediate tissue), and the loose connective tissue (intermediate tissue) is vibrated by a small oscillator to generate a shear wave which is a mechanical vibration wave, and it is a method and apparatus for displaying the hardness of a body tissue for imaging the propagation speed of the mechanical vibration wave (transverse wave) transmitted through the body tissue by an ultrasonic probe. In particular, it relates to an apparatus used for evaluating the mobility of loose connective tissue (intermediate tissue) of a thin layer structure such as ligaments and fascia in the locomotor system or fascia tissue.

[0002] Here, loose connective tissue refers to a tissue containing collagen fibers that connects the boundaries of soft tissues, and is a concept that includes any of the fascia in muscle, the surrounding synovial bursa and adipose tissue in tendon, the surrounding fat, synovial bursa, and synovium in ligament, and the neurilemma in peripheral nerves. When these loose connective tissues are abnormal, adhesions, density changes, inflammation associated with adhesions, problems with body motility, etc. occur, and the hardness display method of the present invention enables evaluation of these problems.

[0003] In addition, examples of abnormalities in body tissues other than muscle and tendon include problems such as tumors (e.g., cancer), tissue necrosis and inflammation, adhesions and fibrosis between tissues, and changes in macro elastic structures. The hardness display method of the present invention enables evaluation of these problems.

Background Art

[0004] An important tissue clinically in the locomotor system is fascia tissue. Although the fascia tissue is less than 1 mm thick, it wraps around individual muscle fibers, muscles, or muscle groups, and plays an important role in smoothing and controlling the movement of muscles and joints while maintaining their shape.

[0005] For example, myofascial pain syndrome (MPS) is thought to be primarily caused by decreased fascial mobility, and while treatments such as hydrorelease are administered, there is a lack of sufficient research into the mechanisms of pain development and the effectiveness of these treatments.

[0006] This current situation is likely due in part to the lack of methods for visualizing fascia and evaluating its condition. In other words, if the muscle structure of specific areas of body tissue could be visualized while the organism is awake, and the condition of the fascia could be evaluated, it would lead to treatment for myofascial pain syndrome (MPS). However, methods and devices for visualizing the fascial tissue itself within the body have not yet been established.

[0007] For reference, WO2015 / 151972 (see Patent Document 1) is a conventional ultrasound imaging method for visualizing the tissues of living organisms (human or animal) using ultrasound. In this disclosure, a puncture needle is pressed against the body surface near the measurement site to vibrate the living cells at the puncture site, and the propagation speed of mechanical vibration waves (transverse waves) traveling through the tissue is imaged using an ultrasound echo device.

[0008] Furthermore, Patent Document 1 (Canon Medical Systems Corporation, Patent Registration No. 05513976) discloses a conventional ultrasound diagnostic device. This device comprises an ultrasound probe, an ultrasound transmitting and receiving unit that repeatedly transmits and receives ultrasound N times to each of a plurality of ultrasound rasters via the ultrasound probe to generate an echo signal, an echo processing unit that generates complex data from the echo signal via quadrature detection processing, a phase correction unit that, for each set of N sets of complex data relating to the same depth and the same ultrasound raster, identifies a phase difference with respect to the reference phase of any of the N complex data for each set, and shifts the phase of the N complex data for each set by the identified phase difference, an interpolation processing unit that generates an interpolation set of complex data relating to interpolation rasters between adjacent ultrasound rasters by interpolation processing from the set of N complex data whose phases have been shifted, and an image data generation unit that generates image data relating to blood flow or movement information of other moving objects via autocorrelation processing from the set of N complex data whose phases have been corrected and the interpolation set generated by the interpolation processing. Furthermore, when N is an even number, the average of the phase difference for the N / 2th complex data point and the phase difference for the (N / 2)+1th complex data point in the set of complex data points is determined.

[0009] In addition, Patent Document 2 (Canon Medical Systems Corporation, Patent Registration No. 06058295) discloses a conventional ultrasound diagnostic device, medical image processing device, medical image processing method, and medical image processing program. In this ultrasound diagnostic device, the autocorrelation calculator calculates autocorrelation values ​​for the blood flow Doppler component and the tissue Doppler component. Based on the calculated autocorrelation values, the autocorrelation calculator calculates the average velocity value, variance value, and Doppler signal reflection intensity (power) of the blood flow and tissue. The velocity / variance / power calculation device generates color Doppler data at each position in a predetermined region based on the average velocity value, variance value, and Doppler signal reflection intensity of the blood flow and tissue based on multiple Doppler signals.

[0010] The displacement calculation unit approximates the tissue displacement related to the subject's body movement (body movement displacement) for each depth in the second region, based on the tissue displacement obtained by the autocorrelation analyzer before the transmission of the push pulse (hereinafter referred to as the first displacement data) and the tissue displacement obtained by the autocorrelation calculator after the transmission of the push pulse (hereinafter referred to as the second displacement data), specifically the tissue displacement near the end of the nth ultrasonic transmission / reception (nth time, (n-1)th time, etc.). The displacement calculation unit calculates the tissue displacement associated with shear wave propagation (hereinafter referred to as shear wave propagation data) by subtracting the approximated body movement displacement from the first and second displacement data.

[0011] Furthermore, another method for measuring the stiffness of body tissues from the outside is disclosed: "Image method for bio-stiffness using shear waves" (WO 2015 / 151972, Patent Document 3). [Prior art documents] [Patent Documents]

[0012] [Patent Document 1] Tokuto-05513976 Publication [Patent Document 2] Tokuto-06058295 Publication [Patent Document 3] WO2015 / 151972A1 publication [Overview of the project] [Problems that the invention aims to solve]

[0013] However, the tablet ultrasound devices described in the above-mentioned literature all visualize the ultrasound image at a set depth within the detected range as a two-dimensional image, and display the ultrasound propagation velocity at each coordinate within the two-dimensional image. Therefore, even if they compare and display biological stiffness at a set depth, or evaluate areas with different stiffness within the image, they do not compare and display the changes in values ​​at each depth.

[0014] Furthermore, in biological tissues, particularly fascial tissue, relatively stiff fibrous layers overlap at different intervals, with relatively low-density loose connective tissue, or so-called intermediate tissue, existing between them. The stiffness of such intermediate tissue cannot be detected by conventional two-dimensional imaging tablet ultrasound devices, and its mobility has not been accurately evaluated.

[0015] Therefore, the object of the present invention is to provide a shear wave image processing method and processing device that can compare and display changes in stiffness at each depth, and evaluate more accurately, particularly in the loose connective tissue (intermediate layer) sandwiched between hard layers in the fascial tissue of living organisms, as a method for obtaining stiffness images of body tissue. [Means for solving the problem]

[0016] To solve the above problems, the present invention employs the following measures. However, the numbers or letters following the names of the components below are merely symbols added for convenience in understanding the drawings and are not intended to limit the concept, shape, or structure of the components.

[0017] [1] A method for displaying the mobility of body tissue, comprising applying pressure to a vibrator in contact with the surface of a living organism to cause sinusoidal vibration of the fascial tissue of the body, simultaneously applying an ultrasonic probe near the body surface to transmit and receive ultrasonic signals, acquiring a shear wave image based on the received ultrasonic signal, and displaying the state of the loose connective tissue of the body tissue as an image on a display device, The loosely connected tissue in a predetermined depth range within a predetermined excitation range of the body tissue that has been contact-excited by the aforementioned vibrator is defined as the image region (detection region). A "shear velocity image acquisition step" is performed to acquire shear velocity images for each depth included in the predetermined depth range, based on ultrasonic Doppler signal components due to displacement fluctuations in the image area (detection area) detected orthogonally by the transmission and reception of ultrasonic signals by the ultrasonic probe, The "velocity peak detection step" involves comparing the acquired shear velocity images at each depth to detect multiple peaks of shear wave velocity values ​​in the image region (detection region) (for example, defining values ​​exceeding a threshold of 2 m / s or more as peak values, and the maximum value within the range exceeding this threshold). A "shear strain calculation step" is performed to calculate the shear strain between the multiple peaks based on the values ​​of each of the multiple peaks of shear wave velocity detected in the "velocity peak detection step" and the depth of each peak (and the amplitude and phase values ​​of the sinusoidal oscillation), The "Mobility Display Addition Step" adds a "mobility display" related to the mobility of the loosely connected tissue, corresponding to the shear strain value calculated in the "Shear Strain Calculation Step," to the shear rate image, along with the display of the corresponding location between the multiple detected peaks. The device is characterized by comprising a "movement display step" which involves continuously acquiring a shear velocity image to which mobility display has been added by the "mobility display addition step" as a plurality of shear wave images (consisting of the first to the Nth frame images), and continuously displaying them on the display device according to the scanning range of the ultrasound probe as the state of loosely connected tissue of the body tissue during scanning by the ultrasound probe.

[0018] The peaks detected in this velocity peak detection step correspond to high-rigidity tissues, such as fibrous layers, inflammatory sclerosis edges, and thin films within the tissue, as shown in Figures 3 and 4. If multiple peaks are detected and the depth difference between peaks, i.e., the distance between peaks, is less than or equal to a certain distance, it can be determined that the area between them is loosely connected tissue.

[0019] Furthermore, the mobility display refers to a display that represents an index of the mobility of loose connective tissue, and includes at least one of the following: a numerical display corresponding to the calculated shear strain value, multiple stepwise coloring patterns, multiple shade patterns, or a selection display that selects and displays one that satisfies the level conditions corresponding to the shear strain value from among multiple pattern patterns. In addition, the peak of the shear wave velocity value is determined to be a peak when the amount of change in the value is judged to have changed rapidly when the shear wave velocity value is calculated over a set predetermined depth direction and the value exceeds a predetermined threshold, and the value is also judged to be above the predetermined threshold. This peak is estimated to be a relatively hard layer in the body tissue, and if the depth difference between the peaks of two adjacent layers is below a predetermined threshold, it is judged to be a three-layer model consisting of upper and lower relatively hard layers and an intermediate layer of loose connective tissue between them. However, the measurement direction of the peak depth difference refers to the depth in an arbitrarily set predetermined depth direction, and is not limited to the direction perpendicular to the body surface. In a three-layer structure model of body tissue, by changing the angle in the depth direction when measuring the interlayer distance between the upper and lower, relatively rigid layers, it is possible to determine that it is a three-layer model with loose connective tissue in between, and to obtain the interlayer distance between the upper and lower two layers.

[0020] [2] The aforementioned ultrasonic probe receives the ultrasonic Doppler signal component that has undergone the Doppler effect in the image region by quadrature detection. The shear strain calculation step includes an "amplitude / phase calculation step" which identifies a minute portion of the image region (detection region) where the ultrasonic probe received the ultrasonic Doppler signal component, and calculates the displacement amplitude and shear wave phase distribution in this minute portion of the image region (detection region), either before or during the shear strain calculation step. In the "shear strain calculation step", based on the amplitude values a1 and a2 of two adjacent peaks (the first peak and the second peak) among the plurality of peaks of the shear wave velocity values detected in the "velocity peak detection step", the depth difference, i.e., the peak interval L, between the depths of the peaks (where the depth direction to be detected may be viewed horizontally), as well as the amplitude values (a1a2) and phase difference (Δθ) of the sine wave vibration calculated in the "amplitude and phase calculation step", the shear strain between the plurality of peaks is calculated.

[0021] [3] In the "shear strain calculation step", based on the depth difference between two adjacent peaks (the first peak and the second peak) among the plurality of peaks of the shear wave velocity values detected in the "velocity peak detection step", it is determined whether the body tissue at the corresponding location corresponds to loose connective tissue sandwiched between hard layers in the fascia of the body tissue and not containing other hard layers, or corresponds to a three-layer structure model (a three-layer structure model composed of a loose connective tissue layer and a hard layer) with a depth difference L below a predetermined threshold value. When it is determined that it corresponds to loose connective tissue, the shear strain between the plurality of peaks is calculated.

[0022] [4] In the "mobility display addition step", the "mobility display" regarding the mobility of loose connective tissue is variably displayed step by step according to the value of the shear strain as a plurality of coloring patterns, a plurality of shading patterns, or a plurality of pattern patterns, and is semi-transparently displayed superimposed on the corresponding location between the plurality of detected peaks in the image of the shear velocity image together with the display of the corresponding location between the plurality of detected peaks.

[0023] [5] The apparatus for displaying the mobility of body tissue according to the present invention a vibrator that pressurizes and contacts the body surface of a living body to vibrate the fascia tissue of the body tissue with a sine wave, an ultrasonic probe that contacts the body surface near the body surface to transmit and receive ultrasonic signals, A processing device that acquires shear wave images based on received ultrasound signals and processes the state of loose connective tissue in body tissue, A display device for the mobility of body tissue, comprising: a processing device that processes a shear wave image including the state of loosely connected tissue in the body tissue and displays it on a display unit; The aforementioned ultrasonic probe uses a predetermined depth range of loosely connected tissue within a predetermined excitation range of body tissue that has been contact-excited by a vibrator as its image region (detection region), and receives the ultrasonic Doppler signal component that has been affected by the Doppler effect in the image region (detection region) by quadrature detection. Furthermore, the processing device includes a "shear velocity image acquisition step" in which it acquires shear velocity images for each depth included in the predetermined depth range by transmitting and receiving ultrasonic signals using the ultrasonic probe, The "velocity peak detection step" involves comparing the acquired shear velocity images at each depth to detect "multiple peaks" in the shear wave velocity values ​​within the image region (detection region), and A "shear strain calculation step" is performed to calculate the shear strain between the multiple peaks based on the values ​​of the multiple peaks of the shear wave velocity detected in the "velocity peak detection step" and the depth of each peak (and the amplitude and phase values ​​of the sinusoidal oscillation), The "Mobility Display Addition Step" adds a "mobility display" related to the mobility of the loosely connected tissue, corresponding to the shear strain value calculated in the "Shear Strain Calculation Step," to the shear rate image, along with the display of the corresponding location between the multiple detected peaks. The shear velocity image to which the mobility display has been added in the "mobility display addition step" is acquired sequentially as multiple shear wave images (consisting of the 1st to Nth frame images). The display device continuously displays the state of loose connective tissue in the body tissue during scanning by the ultrasound probe, according to the scanning range of the ultrasound probe. [Effects of the Invention]

[0024] As described above, the display device and display method for the mobility of body tissue provided by the present invention make it possible to visualize the shear strain at each location by comparing shear wave velocity images of body tissue at each depth.

[0025] This makes it possible to compare changes in stiffness at various depths, particularly in loose connective tissue (intermediate tissue) sandwiched between rigid layers in biological fascial tissue, and visualize them as shear strain images, thereby more accurately evaluating the mobility of loose connective tissue (intermediate tissue). [Brief explanation of the drawing]

[0026] [Figure 1] Diagram illustrating the configuration of the body tissue mobility display device in Example 1. [Figure 2] Flowchart of the processing steps in the method for displaying the mobility of body tissues in Example 1. [Figure 3] A conceptual diagram of a fascial model of body tissue. [Figure 4] An illustrative diagram of the shear wave propagation state in the fascia model of the present invention. [Figure 5] Diagram illustrating the displacement amplitude of shear wave propagation in a fascia model. [Figure 6] Explanation of the formula for calculating shear strain due to shear wave propagation in a fascial model. [Figure 7] A correlation diagram between shear strain and phase difference, based on the shear strain calculation formula. [Figure 8] Examples of displays for the shear wave image (left) and a partially high-resolution velocity image (right) obtained by processing a portion of that area with high resolution. [Figure 9] Examples of each display: a shear wave image (left) and a movable image (right) with movableness indicators added to a portion of that area. [Figure 10] Examples of displays for the shear wave image (left) and a partially high-resolution velocity image (right) obtained by processing a portion of that area with high resolution. [Figure 11] Examples of displays for the shear wave image (left) and a partially high-resolution velocity image (right) obtained by processing a portion of that area with high resolution. [Figure 12] A photograph showing an example of measuring the calf tendon (Achilles tendon) using the device of the present invention. [Figure 13] Figure 12 shows an example of a display image showing the shear wave propagation velocity in the fiber direction (X direction) based on measurements. [Figure 14] A comparison of the shear wave propagation velocity display image in Figure 13, showing the relaxed state (left) and the extended state (right). [Figure 15] A comparison of images from Figure 14, processed and displayed at high resolution, showing the relaxed state (left) and the extended state (right). [Figure 16] A comparison of images of Figure 14 in a movable state, showing the relaxed state (left) and the extended state (right). [Figure 17] Examples of switching between display images for shear wave propagation velocity in an extended state (top), (middle), (bottom). [Figure 18] An explanatory diagram showing the two factors (top) and (bottom) of shear strain in a fascial model of shear wave propagation. [Figure 19] Examples of switching between display images for shear wave propagation velocity in a relaxed state (top), (middle), (bottom). [Modes for carrying out the invention]

[0027] The present invention relates to an apparatus and method for non-invasively measuring and visualizing the stiffness of body tissues of living organisms, and more particularly to an apparatus that visualizes the shear wave strain of loose connective tissue (intermediate tissue) interposed between relatively stiff fibrous layers in the fascial tissue of the fascial model shown in Figures 3 and 4, and displays it in a way that allows evaluation of its mobility as a movable layer.

[0028] In the fascial tissue of the fascial models shown in Figures 3 and 4, a relatively soft layer of loose connective tissue (intermediate tissue) exists between the relatively stiff fibrous layers.

[0029] In the musculoskeletal system, fascial tissue is clinically important. Although less than 1 mm thick, fascial tissue surrounds individual muscle fibers, muscles, or muscle groups, playing a crucial role in smoothing muscle and joint movement while also controlling and maintaining their shape.

[0030] Myofascial pain syndrome (MPS) is thought to be primarily caused by decreased fascial mobility, and while treatments such as hydrorelease are administered, there is a lack of sufficient research into the mechanisms of pain development and the effectiveness of these treatments.

[0031] One method involves vibrating biological tissue with a vibrator under the condition that the muscle vibration frequency is constant, and obtaining an image of the shear waves of the biological tissue during the vibration state using an ultrasonic probe. In this method, a predetermined range of the biological tissue is continuously vibrated at a constant vibration frequency, and a shear wave image is acquired in conjunction with the transmission and reception range of the ultrasonic probe.

[0032] In acquiring the shear wave images, the present invention uses a three-layer structure model, represented by the fascia model shown in Figures 3 and 4, which has a relatively soft loose connective tissue (intermediate layer) sandwiched between two relatively rigid layers, as the detection range for the image area. However, the thickness of each layer is 1 to several millimeters.

[0033] In the loosely connected structure (intermediate layer), sinusoidal excitation from the vibrator causes minute fluctuations of 1 to several micrometers at the boundary with the relatively rigid fiber layers at both ends due to the propagation of shear waves (Figure 4). At this time, there is a large difference in the amount of fluctuation between one fiber layer and the nearby loosely connected structure (intermediate layer), so the shear wave propagation velocity at this location is larger than at other locations. By obtaining the displacement amplitude using ultrasonic detection during vibration and then obtaining the shear wave phase distribution, the shear wave velocity can be calculated, and a peak in the velocity value can be detected near the fiber layer.

[0034] If multiple peaks of this velocity value are detected in a predetermined detection depth direction, and the distance between adjacent first and second peaks is less than or equal to a certain distance, then it is determined that the structure is a three-layer structure in which each of the first and second peaks is a fibrous layer, with loose connective tissue present between them.

[0035] In this invention, the elasticity of the first fiber layer with the first peak, the second fiber layer with the second peak, and the loosely connected tissue between them is detected in the interlayer direction, i.e., the depth direction, of the three-layer structure. This is obtained as a two-dimensional shear strain image of the propagation speed of the shear wave, and this is superimposed on the corresponding part of the B-mode image to visualize the mobility of the body tissue (Figures 9, 11, 16, and 17 below).

[0036] Furthermore, the "predetermined depth direction" (direction L in Figure 5) for detection is not limited to the direction perpendicular to the biological surface to which the ultrasonic probe's transducer is pressed (direction Z in Figure 5), but also includes oblique directions with a predetermined inclination to the left or right, or front or back. In other words, in the three-layer structure, the direction of depth in which detection is advanced can be arbitrarily set and changed depending on the site and measurement item, including not only the x and z directions within the search area, but also oblique and circumferential directions.

[0037] More specifically, the present invention provides a method for displaying the mobility of a body tissue, which involves applying pressure to the surface of a living organism to cause the tissue to vibrate sinusoidally, transmitting and receiving ultrasonic signals from near the surface into the tissue, and continuously acquiring a plurality of shear wave images consisting of first to N frames to display the state of the muscle tissue in a video. The loosely connected tissue in a predetermined depth range within a predetermined excitation range of the body tissue that has been contact-excited by the aforementioned vibrator is defined as the image region (detection region). A "shear velocity image acquisition step" is performed to acquire shear velocity images for each depth included in the predetermined depth range, based on ultrasonic Doppler signal components due to displacement fluctuations in the image area (detection area) detected orthogonally by the transmission and reception of ultrasonic signals by the ultrasonic probe, The "velocity peak detection step" involves comparing the acquired shear velocity images at each depth to detect "multiple peaks" in the shear wave velocity values ​​within the image region (detection region), and A "shear strain calculation step" is performed to calculate the shear strain between the multiple peaks based on the values ​​of each of the multiple peaks of shear wave velocity detected in the "velocity peak detection step" and the depth of each peak (and the amplitude and phase values ​​of the sinusoidal oscillation), The "Mobility Display Addition Step" adds a "mobility display" related to the mobility of the loosely connected tissue, corresponding to the shear strain value calculated in the "Shear Strain Calculation Step," to the shear rate image, along with the display of the corresponding location between the multiple detected peaks. The system includes a "movement display step" which involves continuously acquiring the shear velocity image to which the mobility display has been added by the "mobility display addition step" as a plurality of shear wave images (consisting of the first to the Nth frame images), and continuously displaying them on the display device according to the scanning range of the ultrasound probe as the state of loosely connected tissue in the body tissue during scanning by the ultrasound probe.

[0038] Furthermore, in the processing method described above, The system may also include an "arbitrary setting step" for arbitrarily setting a specific image region (Doppler image region) that is included in the image region and has an arbitrary size and an arbitrary angle with respect to the biological surface.

[0039] In this step, the orientation of muscle fibers within the observed area is simultaneously observed using ultrasound imaging, and the tilt of the micro-region is adaptively changed according to the observation results of the ultrasound imaging.

[0040] In pennate muscles, such as the gastrocnemius muscle, where the direction of the fibers does not coincide with the direction of action, the fiber orientation does not coincide with the longitudinal direction of the muscle but is oriented diagonally. When applying this method to such pennate muscles, the system first observes the fiber orientation using echocardiography (B-mode imaging), and then, by tilting a micro-region in the direction of the fiber orientation, it is possible to observe the elastic properties of the fibers within the muscle with high resolution. The system then estimates the pressure on the living body from the temporal variation of the excitation frequency and displays it on the screen.

[0041] ("Amplitude and Phase Calculation Step") The system includes an "amplitude and phase calculation step" which identifies a minute portion of the image region (detection region) where the ultrasonic probe has received an ultrasonic Doppler signal component, and calculates the displacement amplitude and shear wave phase distribution in this minute portion of the image region (detection region), either before or during the shear strain calculation step.

[0042] Specifically, when the three-layer model shown in Figure 5 is defined, the displacement amplitude in the layer direction, i.e., the x-axis direction, of the first stiff layer (StiffLayer1), which is the first fiber layer, and the second stiff layer (StiffLayer2), which is the second fiber layer, are given by the equation shown in Figure 5(1). As each layer is sinusoidally displaced by the sinusoidal vibration of the exciter, the shear strain of the loosely coupled intermediate layer is given by equation (2) in Figure 6. Substituting equation (1) into equation (2) leads to equation (3) in Figure 6, and thus the magnitude of the shear strain generated in the loosely coupled intermediate layer of the three layers due to shear wave propagation is defined by equation (4) in Figure 6.

[0043] Equation 6(4) in Figure 6 is divided into cases 1), 2), and 3) in Figure 7 depending on the relationship between amplitudes a1 and a2 and the value of the phase difference Δθ. When amplitudes a1 and a2 are equal and the phase difference Δθ is zero, no shear strain occurs, as shown in Figure 7(1). When amplitudes a1 and a2 are different and the phase difference Δθ is zero, the shear strain is proportional to the difference in amplitude between the two layers, as shown in Figure 7(2). Furthermore, when amplitudes a1 and a2 are equal, it can be seen that, as long as the phase difference Δθ is not zero, the shear strain is approximately proportional to the phase difference Δθ, as shown in Figure 7(3).

[0044] Because of this proportional relationship, the magnitude of the shear strain can be determined from the phase difference. The amplitude-phase calculation step and the shear strain calculation step are performed using this proportional relationship.

[0045] ("Shear Strain Calculation Step") In the "shear strain calculation step," the shear strain between multiple peaks is calculated based on the amplitude values ​​and depths of two adjacent peaks (first peak and second peak) among the multiple peaks of shear wave velocity detected in the "velocity peak detection step," as well as the amplitude values ​​and phase difference of the sinusoidal oscillations calculated in the "amplitude and phase calculation step."

[0046] In the "shear strain calculation step," two adjacent peaks (first peak and second peak) are selected from among the multiple peaks of shear wave velocity detected in the "velocity peak detection step," and it is determined whether the depth difference between each peak is below a predetermined threshold. If the depth difference is below the threshold, it is determined whether the body tissue at that location is a three-layer structure consisting of loose connective tissue sandwiched between rigid layers of fascia and not containing other rigid layers, and the shear strain between the multiple peaks is calculated.

[0047] If the depth difference exceeds a threshold, it is determined that the structure does not include a three-layer structure containing loosely connected tissue. In this case, the process does not proceed to the stage of calculating the shear strain between the multiple peaks in question.

[0048] Furthermore, when calculating the depth difference, the "predetermined depth direction" is not limited to the direction perpendicular to the biological surface to which the ultrasound probe's transducer is pressed, but also includes oblique directions with a predetermined inclination to the left or right, or front or back. The distance between the two fiber layers is determined by the difference in depth direction of the multiple detected peaks (the difference in each Z coordinate), This "depth direction" can be set not only in a direction perpendicular to the biological surface, but also in any direction, such as a direction tilted at a specific angle relative to the biological surface, as set by the user.

[0049] In other words, although the fiber layers in Figures 3 and 4 are shown in a roughly horizontal direction for convenience, the actual fiber layers are not limited to being parallel to the biological surface. Therefore, the angle in the depth direction is set not only in the direction perpendicular to the body surface, but also in the angle corresponding to the direction of the fiber layer, and the difference in depth at this set angle in the depth direction is defined as the inter-fiber distance.

[0050] In the "Mobility Indication Addition Step," the "mobility indication" related to the mobility of loosely connected tissue is displayed in a stepwise variable manner according to the value of shear strain, using multiple color patterns, multiple shade patterns, or multiple graphic patterns. Along with displaying the corresponding location between the multiple detected peaks, the shear rate image is superimposed with a semi-transparent display over the corresponding location between the multiple detected peaks (Figure 9 right, Figure 11 right, Figure 16, Figure 17 bottom, Figure 19 bottom). In the flowchart of Figure 2, the colored, or semi-transparent, color represents the movable display.

[0051] Shear strain is based on two factors shown in Figure 18 (top and bottom): the amplitude difference between the two layers shown in Figure 18 (top) and the phase difference between the two layers shown in Figure 18 (bottom). In a three-layer structure sandwiched between a first fiber layer and a second fiber layer, the amplitude difference between two layers is the phase shift of each layer, and the phase difference between two layers is the difference in amplitude of each layer. Since shear strain occurs when these two factors combine, a further step may be taken to visualize and display the "shear strain caused solely by the phase difference" and the "shear strain caused solely by the amplitude difference" in order to determine which is the primary factor (Figure 19, bottom).

[0052] The "video display step" is a step in which a shear wave image is obtained using the estimated excitation frequency. In this step, the excitation frequency estimated in the frequency estimation step is displayed together with the shear wave image.

[0053] In this step, the excitation frequency is estimated frame by frame (automatic tracking) using upsampling and short-time autocorrelation from the ultrasonic Doppler signal. Each frame image from the start time to the end time is equalized to the estimated excitation frequency. A continuous image group consisting of a set of frame images at a certain time interval at the excitation frequency is created intermittently at predetermined elapsed time intervals and transmitted intermittently at predetermined elapsed time intervals. The continuous image group is received and output in chronological order to play back the shear wave video as an animation.

[0054] The present invention provides a display device for the mobility of body tissues, as shown in Figure 1. A vibrator that applies pressure to the surface of a living organism to cause sinusoidal vibrations in the fascial tissue of the body, An ultrasonic probe that transmits and receives ultrasonic signals by contacting the body surface near the body surface, A processing device that acquires shear wave images based on received ultrasound signals and processes the state of loose connective tissue in body tissue, It consists of a processing unit and a display device that displays a shear wave image, including the state of loosely connected tissue in body tissue, on a display unit.

[0055] An ultrasonic probe uses a vibrator to contact-excite body tissue, and defines the loosely connected tissue in a predetermined depth range in a predetermined depth direction within a predetermined excitation range as the image region (detection region). It receives the ultrasonic Doppler signal component affected by the Doppler effect in the image region (detection region) using quadrature detection. The shape and depth of the image region (detection region) may be changeable by setting.

[0056] The processing device includes a "shear velocity image acquisition step" in which it acquires shear velocity images for each depth included in the predetermined depth range by transmitting and receiving ultrasonic signals using the ultrasonic probe, The "velocity peak detection step" involves comparing the acquired shear velocity images at each depth to detect "multiple peaks" in the shear wave velocity values ​​within the image region (detection region), and A "shear strain calculation step" is performed to calculate the shear strain between the multiple peaks based on the values ​​of the multiple peaks of the shear wave velocity detected in the "velocity peak detection step" and the depth of each peak (and the amplitude and phase values ​​of the sinusoidal oscillation), The "Mobility Display Addition Step" adds a "mobility display," consisting of a colored indicator of the mobility of the loosely connected tissue, corresponding to the shear strain value calculated in the "Shear Strain Calculation Step," to the shear rate image, along with the display of the corresponding location between the multiple detected peaks. The shear velocity image, to which the mobility display has been added in the "mobility display addition step," is acquired sequentially as multiple shear wave images (consisting of the 1st to Nth frame images).

[0057] In the "shear strain display step," the display device overlays a shear strain image, which shows the state of loose connective tissue in the body tissue during scanning by the ultrasound probe, onto the image of the image area (B-mode image) of the ultrasound probe on the display device, either partially or entirely, depending on the scanning range of the ultrasound probe.

[0058] When vibrations with a frequency of approximately 1 kHz or less are applied using a small vibrator, the vibrations propagate through the object as shear waves. At the same time, if an ultrasonic pulse is transmitted from an ultrasonic probe to the object, the ultrasonic waves reflected from scatterers within the object and received by the ultrasonic probe undergo phase modulation due to the Doppler effect.

[0059] At this time, the ultrasonic signal reflected from a position (x, z) within the target object is represented using the following parameters. a: Ultrasonic amplitude f0: Center frequency of ultrasound C: Speed ​​of sound ξ0: Displacement amplitude of the shear wave ωb ::Angular frequency of shear waves θ(x,z): Phase of the shear wave.

[0060] (Setting the size of the micro-region according to the organ being observed) By changing the size of the imaging area (detection area) or the depth direction detected by the ultrasound probe according to the biological organ being imaged, it is possible to stabilize the reconstructed image and achieve high resolution that corresponds to the elastic structure of the organ.

[0061] For example, in parallel muscles such as the biceps brachii, where the direction of action coincides with the direction of muscle fibers, and in musculoskeletal organs such as tendons and ligaments, the fibrous tissue inside the organ is oriented parallel to the biological surface. In such organs, by selecting a micro-region that is long in the X direction parallel to the biological surface but short in the Z direction perpendicular to it, the orientation, tension, and relaxation of the fibers within the organ can be visualized with high resolution.

[0062] Conversely, in cases of organ fibrosis due to disease, the fibers generally orient themselves randomly. Therefore, by setting the size of a micro-region such that the lengths in the X and Z directions are equal, for example, it becomes possible to observe the organ with spatial resolution independent of the fiber direction.

[0063] Furthermore, since the tensile force of muscle fibers changes depending on muscle tension and relaxation, differences in fiber elasticity can serve as one indicator for evaluating whether the muscle is generating force normally.

[0064] Tendons and ligaments are pulled by external muscles. In this case, even though tendons and ligaments are passive tissues that receive force from external muscles, observing changes in their elasticity allows us to determine whether their function is normal.

[0065] Feature 3: The orientation of muscle fibers within the observed area is simultaneously observed using ultrasound imaging, and the tilt of the minute region is adaptively changed according to the observation results of the ultrasound image.

[0066] In pennate muscles, such as the gastrocnemius muscle, where the direction of the fibers does not coincide with the direction of action, the fiber orientation does not coincide with the longitudinal direction of the muscle but is oriented diagonally. When applying this method to such pennate muscles, the fiber orientation is first observed using ultrasound images (B-mode images), and by tilting a micro-region in the direction of the fiber orientation, the elastic properties of the fibers within the muscle can be observed with high resolution.

[0067] [Example of an embodiment] Examples of displays using the method described here, specifically for shear wave video playback, are shown in Figures 8 to 17 and 19.

[0068] Figures 8 (right), 10 (right), 15 (left and right), and 17 (center) are examples of obtaining and superimposing high-resolution shear wave images with a spatial resolution uniquely determined by the size of each micro-region by dividing the image area into numerous micro-regions and estimating shear wave image parameters such as shear wave velocity and shear wave propagation direction for each micro-region.

[0069] Generally, a single ultrasonic transmission and reception signal can only be reconstructed as a B-mode image, which represents the reflected intensity of the ultrasound as a grayscale image. In the case of the shear wave image we are aiming for, one image is reconstructed from 8 to 16 consecutive ultrasonic reception signals. This reconstruction assumes that the reception interval of the ultrasound is always constant, so if the reception interval varies, noise may be introduced into the reconstructed image, or the quantitative accuracy of the resulting image may decrease.

[0070] To address this issue, the present invention generates shear strain images according to the following key points 1 to 3, thereby eliminating noise generation and a decrease in quantitative accuracy (Figures 11, 16, and 17).

[0071] (Key point 1 of the present invention) The essence of the present invention lies in a method for displaying the mobility of body tissue, which involves acquiring a shear wave image based on a received ultrasonic signal and displaying the state of loose connective tissue in the body tissue as an image on a display device.

[0072] Specifically, the loosely connected tissue in a predetermined depth range within a predetermined excitation range of body tissue that has been contact-excited by a vibrator is defined as the image region (detection region). The "shear velocity image acquisition step" involves acquiring shear velocity images for each depth included in the predetermined depth range by transmitting and receiving ultrasonic signals using the ultrasonic probe, The "velocity peak detection step" involves comparing the acquired shear velocity images at each depth to detect "multiple peaks" in the shear wave velocity values ​​within the image region (detection region), and A "shear strain calculation step" is performed to calculate the shear strain between the multiple peaks based on the values ​​of the multiple peaks of the shear wave velocity detected in the "velocity peak detection step" and the depth of each peak (and the amplitude and phase values ​​of the sinusoidal oscillation), The "Mobility Display Addition Step" adds a "mobility display" related to the mobility of the loosely connected tissue, corresponding to the shear strain value calculated in the "Shear Strain Calculation Step," to the shear rate image, along with the display of the corresponding location between the multiple detected peaks. The device is characterized by comprising a "movement display step" which involves continuously acquiring a shear velocity image to which mobility display has been added by the "mobility display addition step" as a plurality of shear wave images (consisting of the first to the Nth frame images), and continuously displaying them on the display device according to the scanning range of the ultrasound probe as the state of loosely connected tissue of the body tissue during scanning by the ultrasound probe.

[0073] By continuously displaying real-time measurements of specific muscle tissue areas within the living body, it is possible to intuitively evaluate the mobility of fascial tissue as a displayed image.

[0074] (Key point of the invention 2) Another key aspect of the present invention is that the magnitude of shear strain caused in the intermediate structure by shear wave propagation is modeled mathematically (Figure 6), thereby deriving a proportional relationship between the shear strain and the phase difference of the excitation wave from the exciter (Figure 7), and based on this proportional relationship, the mobility of the movable layer can be displayed in stages.

[0075] By performing a stepwise mobility assessment of the movable layer, along with specifying the relevant area, it is possible to intuitively detect decreased mobility or abnormal mobility in a particular area. Furthermore, in conjunction with the real-time display, it is possible to compare the results with specific postures or muscle conditions.

[0076] In addition to the above, the ultrasonic signals received by each transducer are spectrally analyzed, and through multilayer neural network analysis after training, foreign objects can be classified into one of several object spectral models with different sizes or hardnesses. The classified object spectral models are then displayed on a map with a color or shape that corresponds one-to-one with the detected surface. By having multiple receivers arranged in a two-dimensional array and adjacent receivers overlap in signal detection, the general shape and thickness (depth) of the foreign object can be clearly recognized.

[0077] (Device for measuring biological stiffness) Furthermore, the biological stiffness measuring device of the present invention comprises one of the above-mentioned biological stiffness measuring devices that acquires non-contact detection data, and an analytical device that analyzes the acquired detection data. The biological stiffness measuring device in this biological stiffness measuring device method is used not only for muscle stiffness testing but also for detecting tumors or hardened areas in internal organs.

[0078] It is well known that the stiffness of body tissues changes as diseases such as cancer and liver cirrhosis progress. However, this invention makes the vibrator smaller and lighter, improving operability when obtaining a biopsy, while also enabling non-invasive measurement and visualization of body tissue stiffness. In the musculoskeletal field, this will enable functional evaluation of muscles and tendons, etc. This is expected to be useful in the digestive field for assessing the stiffness of tissues such as the liver, and in the breast for early detection of cancer, etc.

[0079] The measuring device of the present invention can also be applied to internal organs, the thyroid gland, and the mammary glands. For example, in the liver, it is expected that this method will enable the measurement of changes in liver stiffness due to chronic hepatitis, cirrhosis, and non-alcoholic fatty liver, which was previously only possible in the ultrasound rooms of large hospitals, to be performed even in small clinic-level medical facilities. Regarding the mammary glands, it has been pointed out that current X-ray mammography has difficulty in detecting malignant tumors in young women with high breast density, and that there are problems with X-ray exposure. In addition, it has been pointed out that in conventional ultrasound diagnosis, malignant tumors are generally depicted as areas with low echogenicity, and interpretation can be difficult, requiring the experience of the examiner.

[0080] In addition to the above, the present invention allows for intuitive visualization of the hardness of biological tissue caused by malignant tumors, and is therefore expected to facilitate the detection of malignant tumors when used in combination with conventional methods.

Claims

1. A method for displaying the mobility of body tissue, comprising applying pressure to a vibrator in contact with the surface of a living organism to cause sinusoidal vibration of the fascial tissue of the body, simultaneously applying an ultrasonic probe near the body surface to transmit and receive ultrasonic signals, acquiring a shear wave image based on the received ultrasonic signal, and displaying the state of the loose connective tissue of the body tissue as an image on a display device, The loosely connected tissue in a predetermined deep range within a predetermined excitation range of the body tissue that has been contact-excited by the vibrator is defined as the image region. The "shear velocity image acquisition step" involves acquiring shear velocity images for each depth included in the predetermined depth range by transmitting and receiving ultrasonic signals using the ultrasonic probe, The "velocity peak detection step" involves comparing the acquired shear velocity images at each depth to detect multiple peaks in the shear wave velocity value within the image region, A "shear strain calculation step" is performed to calculate the shear strain between the multiple peaks based on the displacement amplitude value of the shear wave velocity value peak detected in the "velocity peak detection step" and the depth information of each peak, The "Mobility Display Addition Step" adds a mobility display related to the mobility of the loosely connected tissue, corresponding to the shear strain value calculated in the "Shear Strain Calculation Step," to the shear rate image, along with the display of the corresponding location between the multiple detected peaks. A method for displaying the mobility of body tissue, comprising: a "movement display step" which continuously acquires a shear velocity image to which mobility display has been added by the "mobility display addition step" as a plurality of shear wave images, and continuously displays them on the display device according to the scanning range of the ultrasound probe as the state of loosely connected tissue of the body tissue during scanning by the ultrasound probe.

2. The aforementioned ultrasonic probe receives the ultrasonic Doppler signal component that has undergone the Doppler effect in the image region by quadrature detection. The shear strain calculation step includes an "amplitude and phase calculation step" which identifies a minute portion of the image region where the ultrasonic probe has received the ultrasonic Doppler signal component, and calculates the displacement amplitude and shear wave phase distribution in this minute portion of the image region, either before or during the shear strain calculation step. The method for displaying the mobility of body tissue according to claim 1, wherein the "shear strain calculation step" calculates the shear strain between multiple peaks based on the amplitude values ​​and depths of two adjacent peaks among the multiple peaks of shear wave velocity values ​​detected by the "velocity peak detection step", and the amplitude values ​​and phase difference of sinusoidal vibrations calculated by the "amplitude and phase calculation step".

3. The method for displaying the mobility of body tissue according to claim 1, wherein in the "shear strain calculation step," based on the difference in depth between two adjacent peaks among a plurality of shear wave velocity values ​​detected in the "velocity peak detection step," it is determined whether the body tissue in the relevant area is loose connective tissue sandwiched between rigid layers of the fascia of the body tissue and not containing any other rigid layers, and if it is determined to be loose connective tissue, the shear strain between the plurality of peaks is calculated.

4. In the aforementioned "Mobility Indication Addition Step," the mobility indication related to the mobility of the loosely connected tissue is displayed in a stepwise variable manner according to the value of the shear strain, using multiple color patterns, multiple shade patterns, or multiple graphic patterns. The method for displaying the mobility of body tissue according to claim 1, wherein the corresponding location between the detected multiple peaks is displayed, and the corresponding location between the detected multiple peaks is displayed semi-transparently superimposed on the shear rate image.

5. A vibrator that applies pressure to the surface of a living organism to cause sinusoidal vibrations in the fascial tissue of the body, An ultrasonic probe that transmits and receives ultrasonic signals by contacting the body surface near the body surface, A processing device that acquires shear wave images based on received ultrasound signals and processes the state of loose connective tissue in body tissue, A display device for the mobility of body tissue, comprising: a processing device that processes a shear wave image including the state of loosely connected tissue in the body tissue and displays it on a display unit; The aforementioned ultrasonic probe uses a predetermined deep range of loosely connected tissue within a predetermined excitation range of body tissue that has been contact-excited by a vibrator as its image region, and receives the ultrasonic Doppler signal component that has undergone the Doppler effect in the image region by quadrature detection. Furthermore, the processing device includes a "shear velocity image acquisition step" in which it acquires shear velocity images of each depth included in the predetermined depth range by transmitting and receiving ultrasonic signals using the ultrasonic probe, The "velocity peak detection step" involves comparing the acquired shear velocity images at each depth to detect multiple peaks in the shear wave velocity value within the image region, A "shear strain calculation step" is performed to calculate the shear strain between the multiple peaks based on the values ​​of the multiple shear wave velocity values ​​detected in the "velocity peak detection step," the depth of each peak, and the amplitude and phase values ​​of the sinusoidal oscillation. The "Mobility Display Addition Step" adds a mobility display related to the mobility of the loosely connected tissue, corresponding to the shear strain value calculated in the "Shear Strain Calculation Step," to the shear rate image, along with the display of the corresponding location between the multiple detected peaks. The shear velocity image to which the mobility display has been added in the "mobility display addition step" is acquired sequentially as multiple shear wave images. A display device for the mobility of body tissue, characterized in that the display device continuously displays the state of loose connective tissue in the body tissue during scanning by the ultrasound probe, according to the scanning range of the ultrasound probe.

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