JP5646290B2 - Ultrasonic diagnostic apparatus and method for operating the same - Google Patents

Description

  The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to a technique for obtaining an elasticity value of a living tissue.

  In ultrasonic diagnosis, diagnosis of benign or malignant tissue is performed based on the hardness and softness (elasticity value) of the tissue at a specific site. Various methods are known as a method for measuring the elasticity value of a living tissue.

  For example, Non-Patent Document 1 discloses a technique (ARFI: Acoustic Radiation Force) that irradiates a region of interest with a focused ultrasonic pulse (push pulse) having a high sound pressure on a living tissue of a subject and pushes the living tissue backward to displace it. Impulse), it has been proposed to obtain an elastic distribution of living tissue. According to this document, the position information is acquired by irradiating the living tissue of the region of interest before displacement with reference pulse, the position information is acquired by irradiating the living tissue of the region of interest after displacement with the search pulse, It has been proposed to obtain a displacement distribution of a living tissue by a push pulse based on the position information of the body and to obtain an elastic distribution of the living tissue based on the displacement distribution.

  Further, in Non-Patent Document 1, since the hardness of the living tissue measured by the above-described method is a relative hardness, when the hardness is quantitatively evaluated, the living tissue displaced by the push pulse is the original. It has been proposed to use a method (hereinafter referred to as dynamic elastography) that measures the propagation velocity of shear elastic waves (transverse waves) that are generated when returning to, and obtains the hardness of a living tissue based on the measured propagation velocity. Yes. Since the tissue having a high propagation speed of the transverse wave is a hard biological tissue and may be malignant, the hard biological tissue is displayed in red to alert the user.

Masahiro Saito, Virtual Palpation, Ultrasound Inspection Technology, Japanese Society of Sonographers, 2008, vol. 33, no. 6, p659-665

By the way, when irradiating ultrasonic waves, the ultrasonic probe is brought into close contact with the body surface of the subject by pressing the ultrasonic probe against the subject. Therefore, stress acts on the living tissue of the subject from the ultrasound probe, and the living tissue becomes hard. Therefore, the method of Non-Patent Document 1 that does not take into account the stress acting on the living tissue cannot measure the true elasticity value and cannot accurately evaluate the elasticity value.

  The problem to be solved by the present invention is an ultrasonic diagnostic apparatus capable of evaluating an elastic value measured by dynamic elastography in consideration of a stress acting by bringing an ultrasonic probe into close contact with a subject. Is to realize.

  In order to solve the above-described problems, an ultrasonic diagnostic apparatus according to the present invention includes an ultrasonic probe that transmits and receives ultrasonic waves to and from a subject, and a measurement region of the biological tissue of the subject from the ultrasonic probe. An elastic value calculation unit that calculates the elastic value of the measurement region by measuring the propagation velocity of the transverse wave generated in the measurement region by the push pulse irradiated on the surface, and generates an elasticity image based on the elastic value obtained by the elastic value calculation unit A push pulse is applied to a reference propagation medium with known characteristics of stress and displacement or elasticity value in an ultrasonic diagnostic apparatus comprising an elasticity image generation unit that performs a display and a display unit that displays an elasticity image generated by the elasticity image generation unit And a stress calculation unit for obtaining a stress applied to the reference propagation medium based on the displacement or elasticity value of the reference propagation medium obtained in this way and the characteristic.

  According to this, by irradiating the reference propagation medium with a push pulse and obtaining the displacement or elasticity value of the medium, the ultrasonic probe can perform the same based on the stress and displacement or elasticity characteristics of the medium. The stress applied to the medium can be determined. Then, the elastic value of the living tissue in the measurement region is obtained by dynamic elastography while maintaining the contact state of the ultrasonic probe when the stress applied to the medium is obtained. Thereby, the elasticity value measured in consideration of the stress applied by the ultrasonic probe can be evaluated for the living tissue in the measurement region.

  In this case, the stress applied by the ultrasonic probe includes the stress applied by the push pulse. For this reason, it is preferable to irradiate the reference propagation medium and the living tissue in the measurement region with the same sound pressure push pulse, but the stress applied by the push pulse is negligibly small compared to the stress from the ultrasonic probe. Therefore, it is possible to measure the displacement or elasticity value of the reference propagation medium and the elasticity value of the living tissue in the measurement region by irradiating the reference propagation medium and the living tissue in the measurement region with different sound pressure push pulses.

  In addition, as a reference propagation medium whose characteristics of stress and displacement or elasticity are known, the fat portion of the subject can be used. On the other hand, when the fat part of the subject is thin, or when the position of the living tissue in the measurement region is shallow, a reference deformable body with known characteristics of stress and displacement or elasticity can be used as the standard propagation medium. That is, the reference deformable body is mounted as a coupler on the transmitting / receiving surface of the ultrasonic probe, and the ultrasonic probe is brought into close contact with the subject via the reference deformable body. In addition, since the characteristics of elastic values (for example, Young's modulus) with respect to stress and the characteristics of displacement with respect to stress are nonlinear in living tissue, when a reference deformable body is used as a reference propagation medium, the characteristics of stress and displacement or elasticity Is preferably non-linear.

  In addition, the position information of the standard propagation medium before displacement by the push pulse is acquired with a reference pulse having a sound pressure lower than that of the push pulse, and the position information after the displacement is acquired by a search pulse having a sound pressure lower than that of the push pulse. The displacement of the reference propagation medium can be obtained, and the stress acting on the reference propagation medium can be obtained based on the displacement. According to this, based on the displacement of the reference propagation medium and the stress-displacement characteristic, the stress acting on the reference propagation medium can be obtained by bringing the ultrasonic probe into close contact with the subject.

  In addition, the elastic value of the reference propagation medium is obtained by dynamic elastography, and the ultrasonic probe is brought into close contact with the subject based on this elasticity value and the stress-elasticity characteristic of the reference propagation medium. Stress to be obtained. According to this, the elasticity value of the measurement region and the reference propagation medium can be obtained by the same method.

  In this case, the first mode in which the transmitter and the reference propagation medium are irradiated with the push pulse and the search pulse, respectively, and the measurement area and the reference propagation medium are irradiated with the push pulse at the same time. At least one of the second mode and the third mode in which the measurement region and the reference propagation medium are irradiated with a common push pulse is stored. In the case of the first mode, the search pulse is irradiated to the measurement region and the reference propagation medium, respectively, and in the case of the second or third mode, a common search pulse is irradiated to the measurement region and the reference propagation medium. Can be configured. In particular, since the timing at which a transverse wave is generated in the measurement region and the reference propagation medium is aligned by the irradiation of the push pulse in the second or third mode, the propagation velocity of the transverse wave in the measurement region and the reference propagation medium can be measured with the same search pulse. . According to this, the measurement time of the propagation speed of the transverse wave can be shortened as compared with the case where the search pulse is separately applied to the measurement region and the reference propagation medium. If shortening of the measurement time is desired, the second mode that requires only one irradiation of the push pulse is adopted. If a clear image is desired, the positional relationship between the measurement region and the reference propagation medium is taken into consideration. Thus, the third mode in which the irradiation condition of the push pulse can be set can be adopted.

  If the elasticity image is displayed in different colors according to the elasticity value of the measurement area, the elasticity value of the measurement area changes depending on the stress from the ultrasonic probe acting on the living tissue in the measurement area. The color coding criteria can be modified based on the measured stress. According to this, since the elasticity image color-coded considering the stress can be displayed, the diagnostic accuracy based on the elasticity image can be improved.

  In addition, the operation method of the ultrasonic diagnostic apparatus of the present invention irradiates the measurement region of the body tissue of the subject with the push pulse from the ultrasonic probe, obtains the propagation velocity of the transverse wave generated in the measurement region, and In the operation method of an ultrasonic diagnostic apparatus that obtains an elasticity value and generates and displays an elasticity image based on the elasticity value, a push pulse is applied to a reference propagation medium whose stress and displacement or elasticity characteristics are known, and the reference propagation is performed. A displacement or elasticity value of the medium is obtained, a stress applied to the reference propagation medium is obtained based on the characteristics, an elasticity value is evaluated based on the stress, and the evaluation is displayed on an elasticity image.

  ADVANTAGE OF THE INVENTION According to this invention, the ultrasonic diagnostic apparatus which can evaluate the elastic value measured by dynamic elastography in consideration of the stress which acts by making an ultrasonic probe contact | adhere to a subject is realizable.

1 is a block diagram illustrating a configuration of an ultrasonic diagnostic apparatus according to Embodiment 1. FIG. It is a figure which shows the positional relationship of a measurement area | region and a fat part. It is a figure which shows the flow of the characteristic operation | movement of Embodiment 1. FIG. It is the figure which showed the color map corresponding to the stress which has acted on the measurement area | region. It is a conceptual diagram which calculates | requires the propagation speed of the transverse wave of a measurement area | region. 6 is a block diagram illustrating a configuration of an ultrasonic diagnostic apparatus according to Embodiment 2. FIG. It is a figure which shows the positional relationship of a measurement area | region and a coupler. 6 is a block diagram illustrating a configuration of an ultrasonic diagnostic apparatus according to Embodiment 3. FIG. It is a figure which shows the flow of the characteristic operation | movement of Embodiment 3. FIG. It is a figure which shows the characteristic of the Young's modulus with respect to the stress of fat. It is the figure which showed the relationship between the stress and Young's modulus in a benign biological tissue and a malignant biological tissue. It is a figure which shows the characteristic of the Young's modulus with respect to the stress of a coupler. It is a figure which shows the timing of irradiation of the push pulse of Embodiment 3.

Hereinafter, the present invention will be described based on embodiments.
(Embodiment 1)
As shown in FIG. 1, the ultrasonic diagnostic apparatus according to the first embodiment includes a probe 2 that can contact an outer skin of a subject 1 and transmit and receive ultrasonic waves. The probe 2 is formed to have an ultrasonic transmission / reception surface on which a plurality of transducers that transmit and receive ultrasonic waves to and from the subject 1 are arranged. The probe 2 is driven by ultrasonic pulses transmitted from the transmission circuit 3. The transmission circuit 3 is, for example, a normal ultrasonic pulse irradiated when creating a tomographic image (B-mode image), a push pulse having a higher sound pressure than the ultrasonic pulse, and a reference having a lower sound pressure than the push pulse. It is configured to be able to transmit by switching the pulse or search pulse. Note that the sound pressure of the reference pulse and the search pulse can be set to be the same as the sound pressure of the normal ultrasonic pulse.

  An ultrasonic transmission / reception control circuit 4 is connected to the transmission circuit 3. The ultrasonic transmission / reception control circuit 4 controls the transmission circuit 3 so that any one of a normal ultrasonic pulse, push pulse, reference pulse, and search pulse is emitted from the probe 2. Further, the transmission timing of ultrasonic pulses for driving a plurality of transducers of the probe 2 is controlled to form ultrasonic pulses toward the focal point set in the subject 1. Furthermore, the ultrasonic transmission / reception control circuit 4 is configured to electronically scan ultrasonic pulses in the arrangement direction of the transducers of the probe 2.

  On the other hand, the probe 2 receives a reflected echo signal generated from the subject 1 and outputs it to the receiving circuit 5. The receiving circuit 5 takes in a reflected echo signal and performs receiving processing such as amplification in accordance with the timing signal input from the ultrasonic transmission / reception control circuit 4. The reflected echo signal received by the receiving circuit 5 is amplified by adding together the phases of the reflected echo signals received by the plurality of transducers in the phasing and adding circuit 6. The RF signal of the reflected echo signal phased and added in the phasing and adding circuit 6 is input to the signal processing unit 7 and subjected to signal processing such as gain correction, log compression, detection, contour enhancement, and filter processing. Note that the RF signal generated in the phasing addition circuit 6 may be a complex demodulated I and Q signal.

  The RF signal processed by the signal processing unit 7 is guided to the black and white scan converter 8 where it is converted into a digital signal and also converted into two-dimensional tomographic image data corresponding to the scanning surface of the ultrasonic beam. The signal processing unit 7 and the monochrome scan converter 8 constitute a tomographic image reconstruction unit. The tomographic image data output from the black-and-white scan converter 8 is supplied to the image display 10 via the switching adder 9 so that a B-mode image is displayed.

On the other hand, when a measurement region (region of interest ROI) for which an elastic value is to be obtained is set, a push pulse is applied to the measurement region, and a reflected echo signal from a transverse wave generated in the measurement region is input to the phasing addition circuit 6. . The RF signal of the reflected echo signal is output from the phasing addition circuit 6. When this RF signal is input to the shear wave sound velocity / Young's modulus calculation unit 13, the shear wave sound velocity / Young's modulus calculation unit 13 estimates the state of the shear wave shape or the like of the measurement region generated by the push pulse from the input RF signal. Then, the propagation velocity of the transverse wave is obtained, and the Young's modulus of the measurement region is calculated from the obtained propagation velocity. That is, the following equation (1) is established between the Young's modulus (E) and the propagation velocity (C) of the transverse wave.
E = 3ρC ² (Equation 1)
Here, since the density (ρ) of the living tissue has a small change for each tissue, for example, assuming that the density is 1.0, the Young's modulus (C) is determined from the propagation speed (C) of the transverse wave based on (Equation 1). E) can be calculated. Then, the transverse wave velocity / Young's modulus calculator 13 outputs Young's modulus frame data in which the Young's modulus is associated with the measurement region of the frame data of the RF signal group corresponding to the scanning plane (tomographic plane) to the elastic data processor 14. It has become.

  The elasticity data processing unit 14 performs various image processing such as smoothing processing in the coordinate plane, contrast optimization processing, and smoothing processing in the time axis direction between frames on the Young's modulus frame data. The color scan converter 15 captures the frame data output from the elastic data processing unit 14 and assigns a color code to each pixel of the frame data according to the set Young's modulus color map to generate a color elastic image. It has become.

  The color elasticity image generated by the color scan converter 15 is displayed on the image display 10 via the switching addition unit 9. The switching addition unit 9 also receives a black and white tomographic image output from the black and white scan converter 8 and a color elastic image output from the color scan converter 15 and switches both images to display one of them. In addition, one of the two images is translucent, added and combined, displayed on the image display 10 and displayed, and the two images are displayed side by side. Further, the cine memory unit 18 stores the image data output from the switching addition unit 9 in the memory, and calls the past image data and displays it on the image display 10 in accordance with a command from the control interface unit 17. Yes. Furthermore, the selected image data can be transferred to a recording medium such as an MO.

  Here, the characteristic part of Embodiment 1 is demonstrated. The first embodiment includes a displacement calculation unit 12 that calculates a displacement of a fat part obtained by irradiating the fat part with a push pulse, for example, a reference propagation medium whose displacement with respect to stress is known. The displacement calculator 12 measures and outputs the displacement of the fat portion due to the push pulse based on the RF signals of the reflected echo signals of the reference pulse and search pulse irradiated to the fat portion. The displacement of the fat part output from the displacement calculation unit 12 is input to the compression state evaluation unit 19. The compression state evaluation unit 19 includes displacement characteristic information with respect to stress in the fat part. Based on the characteristic information and the input displacement, the probe 2 is brought into close contact with the body surface of the subject 1 so as to be attached to the fat part. The stress (pressing force) of the acting probe 2 is obtained, and the obtained stress is evaluated to obtain the stress of the probe 2 acting on the living tissue in the measurement region. Then, the Young's modulus frame data input from the shear wave sound velocity / Young's modulus calculation unit 13 and the obtained stress are associated with each other and output to the color scan converter 15.

  An operation of dynamic elastography performed by the ultrasonic diagnostic apparatus according to the first embodiment configured as described above will be described. When irradiating the ultrasonic wave, the probe 2 is pressed against the subject 1 and brought into close contact with the body surface of the subject 1 by an examiner such as a doctor. Next, a push pulse is transmitted from the transmission circuit 3 to the probe 2 based on the control signal of the ultrasonic transmission / reception control circuit 4, and the push pulse is irradiated to the measurement region. After the push pulse is irradiated, the ultrasonic transmission / reception control circuit 4 controls the transmission circuit 3 so that the probe 2 emits a search pulse having a sound pressure lower than that of the push pulse. At this time, the search pulse is irradiated a plurality of times along the propagation direction of the transverse wave in the measurement region generated by the push pulse. The reflection echo signal of the search pulse is input from the receiving circuit 5 to the phasing addition circuit 6, and the RF signal of the reflection echo signal of the search pulse is output from the phasing addition circuit 6. This RF signal is input to the shear wave sound velocity / Young's modulus calculator 13. The shear wave sound velocity / Young's modulus calculator 13 estimates the shape of the shear wave based on the reception time of the received RF signal, for example. For example, the difference between the irradiation position of the push pulse and the arbitrary position of the transverse wave (transverse distance of the transverse wave) is obtained, and the time until the transverse wave propagates to that position is used as the reception time of each RF signal (irradiation time of each search pulse). Based on these, the propagation speed of the transverse wave is calculated based on these. Then, based on the calculated propagation velocity of the transverse wave and the above-described (Equation 1), Young's modulus in the measurement region is calculated to generate Young's modulus frame data, and this frame data is output to the elastic data processing unit 14. Then, the frame data image-processed by the elastic data processing unit 14 is assigned a color code for each pixel of the frame data in accordance with the Young's modulus color map set in the color scan converter 15 to generate a color elastic image.

  Next, the characteristic operation of the first embodiment will be described with reference to FIGS. 2 and 3 by taking as an example the case where the measurement region (region of interest) is set to the mammary gland in the ultrasound diagnosis of the chest. As shown in FIG. 2, the chest part is located in the order of the fat part, the mammary gland, and the greater pectoral muscle from the side closer to the probe 2. As shown in FIG. 3, when the measurement region is set, the probe 2 is pressed against the outer surface of the subject 1 and pressed to bring the probe 2 and the subject 1 into close contact with each other. Therefore, stress acts on the living tissue in the measurement region of the subject 1 from the probe 2. Since this stress also acts on the fat portion at a position shallower than the living tissue in the measurement region, the fat portion can be used as a reference propagation medium. Therefore, the stress-displacement characteristic of the fat portion is stored in advance in the compression state evaluation unit 19. Then, the fat pulse is irradiated with the push pulse while maintaining the contact state of the probe 2 that has irradiated the measurement region with the push pulse.

  When irradiating a fat part with a push pulse, the fat part is divided into, for example, i lines 31 (S1). Next, the reference position information of the line 31 before irradiating the push pulse with the reference pulse being irradiated a plurality of times on one line 31 is acquired. Then, the line 31 irradiated with the reference pulse is irradiated with a push pulse having the same sound pressure as the push pulse irradiated on the measurement region to cause displacement, and then the search pulse is irradiated onto the line 31 a plurality of times to change the displacement. The position information of the subsequent line 31 is acquired. At this time, the fat part is irradiated with ultrasonic waves while maintaining the pressing force of the probe 2 when the measurement region is irradiated with the push pulse. These pieces of position information are input to the displacement calculation unit 12, and the displacement calculation unit 12 measures the displacement of the measurement point with respect to the push pulse in the line irradiated with the push pulse based on the position information before and after the displacement. This operation is performed for all the lines 31 set in the fat portion, and the displacement at the measurement point of each line 31 is obtained (S2). The obtained displacement is input to the compression state evaluation unit 19, and acts on the measurement point of each line 31 based on the input displacement and the stress-displacement characteristic of the fat portion stored in the compression state evaluation unit 19. The stress is obtained, and the stress distribution in the fat part is obtained (S3). Then, the obtained stress distribution is associated with the Young's modulus frame data of the measurement region, and the stress acting on the measurement region is estimated. For example, the stress acting on the line 31 through which the push pulse irradiated to the measurement region has passed is evaluated and estimated as the stress acting on the measurement region (S4). The estimated stress is input to the color scan converter 15, and the color map is corrected based on the stress. For example, as shown in FIG. 4, when the stress acting on the measurement region is σ1, the color map at the stress σ1 is applied, and when the stress acting on the measurement region is σ2, the color at the stress σ2 is applied. The map is applied. Thereby, an appropriate color map is selected and a color elastic image can be selected. When there are a plurality of measurement points on each line 31, the average value of the displacement and stress at each measurement point can be used as the displacement and stress on each line 31. The color map shown in FIG. 4 can be created in advance by collecting data in clinical practice, for example.

  According to this, since the stress applied by bringing the probe 2 into close contact with the subject 1 is obtained, and the color map which is an evaluation standard of the Young's modulus is corrected based on the obtained stress, the Young's modulus is calculated. Can be evaluated appropriately. That is, the biological tissue becomes hard due to the stress from the probe 2 and the Young's modulus increases. Since the color map can be corrected in response to the increase in Young's modulus, the benign / malignant evaluation based on the Young's modulus can be accurately performed. It can be carried out.

  In the first embodiment, the stress acting on the fat portion is evaluated as the stress acting on the living tissue in the measurement region as it is, but the probe 2 is compressed by the distance from the fat portion to the measurement region. In consideration of force attenuation, the stress acting on the fat region can be evaluated to obtain the stress acting on the measurement region.

  In the first embodiment, the color map is corrected by the stress acting on the measurement region. However, the stress acting on the measurement region can be simply displayed on the color elastic image. In this case, a graph or the like in which the stress applied from the probe 2 is associated with the elasticity value of the living tissue can be created in advance, and a doctor or the like can correct the elasticity value.

  Further, as in the first embodiment, for example, when performing an ultrasonic diagnosis of the chest, the measurement region may be moved by an external force such as a heart beat. In that case, as shown in FIG. 5, before the push pulse is irradiated, the search pulse is irradiated a plurality of times, and the state of the measurement area before the push pulse is irradiated is measured from the reflected echo signal. Can be configured. According to this, it is possible to suppress a decrease in diagnostic accuracy due to an external force such as a heart beat.

  Moreover, although Embodiment 1 calculates | requires the stress distribution of a fat part after calculating the elasticity value of a measurement area | region, this procedure can be reversed. For example, after obtaining the stress distribution of the fat portion, the elasticity value of the measurement region can be calculated.

(Embodiment 2)
The ultrasonic diagnostic apparatus according to the second embodiment will be described with reference to FIGS. The second embodiment differs from the first embodiment in that an acoustic coupler disposed between the probe 2 and the subject is used as a reference propagation medium instead of the fat portion. Since other configurations are the same as those of the first embodiment, the same reference numerals are given and description thereof is omitted.

  The thickness of the fat portion varies depending on individual differences and the diagnosis site, and there is a case where the fat portion having an appropriate thickness is not provided on the upper surface of the measurement region. Therefore, the stress-displacement characteristic of the acoustic coupler 33 is obtained in advance, and this characteristic is stored in the compression state evaluation unit 19. Then, the coupler is divided into a plurality of lines 35, the stress from the probe 2 acting on each line 35 is obtained to create a stress distribution, and the line 35 through which the push pulse irradiated to the measurement region has passed. The corresponding stress is estimated as the stress acting on the living tissue in the measurement region. According to this, the influence by the individual difference of a test subject and a diagnostic site | part can be disregarded, and a diagnostic precision can be improved.

  If the ultrasonic focus cannot be set at a shallow position of the subject 1 and the measurement region cannot be set at a shallow position of the subject 1, an acoustic coupler 33 is interposed between the subject 1 and the probe 2. The measurement region can be set at a shallow position of the subject 1 by moving the probe 2 away from the subject 1. In this case, it is preferable to use the acoustic coupler 33 as a reference propagation medium.

(Embodiment 3)
The ultrasonic diagnostic apparatus according to the third embodiment will be described with reference to FIGS. The third embodiment is different from the first embodiment in that the Young's modulus of the reference propagation medium is obtained instead of the displacement of the reference propagation medium, and the reference propagation medium is determined based on the known characteristics of the Young's modulus and stress of the reference propagation medium. The point is that the stress from the acting probe 2 is obtained. Since other configurations are the same as those of the first embodiment, the same reference numerals are given and description thereof is omitted.

  The compression state evaluation unit 19 stores a characteristic curve of Young's modulus with respect to fat stress as shown in FIG. Then, as shown in FIG. 9, when the measurement region is set, the fat part is divided into a plurality of lines (S11). Next, using the dynamic elastography described above, the propagation speed of the transverse wave generated by irradiating the push pulse for each line is measured based on the RF signal of the reflected echo signal of the search pulse, and the Young's modulus of each line is calculated. (S12). The calculated Young's modulus is input to the compression state evaluation unit 19, and acts on each line based on the input Young's modulus and the stress-Young's modulus characteristics of the fat portion stored in the compression state evaluation unit 19. Stress is obtained, and the stress distribution in the fat portion is obtained (S13). For example, in the case where the stress-Young's modulus characteristic of the fat portion is the curve shown in FIG. 10, if the Young's modulus of a certain line is 5.2 kPa, it can be seen that the stress acting on the line is 0.5 kPa. Then, the obtained stress distribution is associated with Young's modulus frame data, and the stress acting on the measurement region is estimated. For example, the stress of the fat part line through which the push pulse irradiated to the measurement region has passed is evaluated and estimated as the stress acting on the measurement region (S14). FIG. 11 illustrates the relationship between Young's modulus with respect to stress in benign living tissue such as fat and malignant living tissue such as cancer (Krouskop TA, et al. Elastic Moduli of Breast and Prostate Tissue Under Compression. Ultrasonic Imaging. 1998; 20: 260-274.).

  According to this, since the circuit which calculates | requires the Young's modulus of a measurement area | region can be utilized for calculation of the stress which acted on the fat part, compared with Embodiment 1 which calculates | requires the displacement of a fat part, an apparatus can be simplified.

  In the third embodiment, a coupler can be used as a reference propagation medium instead of the fat portion as in the second embodiment. In this case, as shown in FIG. 12, a graph in which the Young's modulus and stress characteristics in the coupler are related can be stored in the compression state evaluation unit 19 in advance.

  Further, when the push pulse is applied to the measurement region and the fat part, respectively, the measurement time is longer than the normal dynamic elastography because the push pulse and the search pulse are applied to the fat part. Therefore, by irradiating the measurement area and the fat part with a common push pulse, it is possible to align the timing at which the transverse wave is generated in the measurement area and the fat part. Measurement can be performed with pulses, reducing measurement time. Further, when the image becomes unclear when the same push pulse is used, as shown in FIG. 13, the irradiation time of the push pulse applied to each of the measurement region and the fat part is made closer so that the timing of generating the transverse wave is aligned. It can be irradiated at the same time. According to this, it is possible to irradiate a push pulse in consideration of the difference in distance between the measurement region and the fat part from the probe 2, and it is possible to suppress the image from becoming unclear.

DESCRIPTION OF SYMBOLS 1 Subject 2 Probe 3 Transmitter circuit 4 Ultrasonic transmission / reception control circuit 5 Receiver circuit
DESCRIPTION OF SYMBOLS 10 Image display device 12 Displacement calculating part 13 Transverse wave sound speed and Young's modulus calculating part 19 Compression state evaluation part

Claims (6)

Propagation of a transverse wave generated in the measurement region by an ultrasonic probe that transmits and receives ultrasonic waves to and from the subject, and a push pulse irradiated from the ultrasonic probe to the measurement region of the biological tissue of the subject An elastic value calculation unit that measures the velocity and obtains an elastic value of the measurement region, an elastic image generation unit that generates an elastic image based on the elastic value obtained by the elastic value calculation unit, and the elastic image generation unit In an ultrasonic diagnostic apparatus comprising: a display unit that displays the elastic image generated in
Stress characteristics of stress and displacement or elasticity is applied before Symbol reference propagation medium based displacement or elasticity of the reference propagation medium obtained by irradiating the push pulse to a known reference propagation medium, the characteristics comprising a stress calculation unit for obtaining a
The elastic value calculation unit measures a propagation speed of a transverse wave generated in the measurement region based on a reflected echo signal of a search pulse whose sound pressure is lower than that of the push pulse irradiated to the measurement region and the reference propagation medium. To obtain the elasticity value,
The transmitter further includes a transmitter for switching and irradiating the push pulse and the search pulse, and the transmitter is configured to irradiate the measurement region and the reference propagation medium with the push pulse, respectively, the measurement region and the reference At least one of a second mode in which the propagating medium is irradiated with a push pulse at the same time, or a third mode in which the measuring area and the reference propagating medium are irradiated with a common push pulse. In this mode, the search pulse is irradiated to the measurement region and the reference propagation medium, respectively, and in the second or third mode, a common search pulse is irradiated to the measurement region and the reference propagation medium. An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 1,
The elasticity image generation unit has a color-coding standard for color-coding the elasticity image according to the elasticity value of the measurement region, and the color-coding standard is corrected based on the stress obtained by the stress calculation unit. A characteristic ultrasonic diagnostic apparatus. Propagation of a transverse wave generated in the measurement region by an ultrasonic probe that transmits and receives ultrasonic waves to and from the subject, and a push pulse irradiated from the ultrasonic probe to the measurement region of the biological tissue of the subject An elastic value calculation unit that measures the velocity and obtains an elastic value of the measurement region, an elastic image generation unit that generates an elastic image based on the elastic value obtained by the elastic value calculation unit, and the elastic image generation unit In an ultrasonic diagnostic apparatus comprising: a display unit that displays the elastic image generated in
The stress applied to the reference propagation medium is calculated based on the displacement or elasticity value of the reference propagation medium obtained by irradiating the push pulse to a reference propagation medium whose stress and displacement or elasticity characteristics are known, and the characteristic. Equipped with the required stress calculator
The elastic value calculation unit measures a propagation speed of a transverse wave generated in the measurement region based on a reflected echo signal of a search pulse whose sound pressure is lower than that of the push pulse irradiated to the measurement region and the reference propagation medium. To obtain the elasticity value,
The elasticity image generation unit has a color-coding standard for color-coding the elasticity image according to the elasticity value of the measurement region, and the color-coding standard is corrected based on the stress obtained by the stress calculation unit. A characteristic ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to any one of claims 1 to 3,
The displacement calculation unit includes a reflected echo signal of a reference pulse having a sound pressure lower than that of the push pulse irradiated to the reference propagation medium, and the push pulse before the reference propagation medium is irradiated with the push pulse. After the irradiation, the displacement generated in the reference propagation medium by the push pulse is obtained based on the reflected echo signal of the search pulse whose sound pressure is lower than that of the push pulse irradiated to the reference propagation medium. Ultrasonic diagnostic equipment. A push pulse is irradiated from the ultrasonic probe to the measurement region of the biological tissue of the subject, the propagation velocity of the transverse wave generated in the measurement region is obtained, the elasticity value of the measurement region is obtained, and the elasticity is determined based on the elasticity value. In an operation method of an ultrasonic diagnostic apparatus for generating and displaying an image,
The displacement or elasticity value of the reference propagation medium obtained by irradiating the push propagation pulse to the reference propagation medium whose stress and displacement or elasticity characteristics are known, and the stress applied to the reference propagation medium based on the characteristics. Seeking
Based on the reflected echo signal of the search pulse having a sound pressure lower than that of the push pulse irradiated to the measurement region and the reference propagation medium, the propagation velocity of the transverse wave generated in the measurement region is measured to obtain the elasticity value, Generating and displaying the elasticity image based on a color-coding standard for color-coding the elasticity image according to the determined elasticity value;
An operation method of an ultrasonic diagnostic apparatus, wherein the color-coded reference is corrected based on the stress applied to the reference propagation medium . A push pulse is irradiated from the ultrasonic probe to the measurement region of the biological tissue of the subject, the propagation velocity of the transverse wave generated in the measurement region is obtained, the elasticity value of the measurement region is obtained, and the elasticity is determined based on the elasticity value. In an operation method of an ultrasonic diagnostic apparatus for generating and displaying an image,
The stress applied to the reference propagation medium is calculated based on the displacement or elasticity value of the reference propagation medium obtained by irradiating the push pulse to a reference propagation medium whose stress and displacement or elasticity characteristics are known, and the characteristic. Seeking
Based on the reflected echo signal of the search pulse having a sound pressure lower than that of the push pulse irradiated to the measurement region and the reference propagation medium, the propagation velocity of the transverse wave generated in the measurement region is measured to obtain the elasticity value,
A first mode in which the measurement region and the reference propagation medium are each irradiated with a push pulse, a second mode in which the measurement region and the reference propagation medium are irradiated at the same time, respectively, or the measurement region and the reference propagation By switching at least one mode among the third modes for irradiating a common push pulse to the medium, in the case of the first mode, the measurement pulse and the reference propagation medium are respectively irradiated with the search pulse, In the second or third mode, the ultrasonic diagnostic apparatus is operated by irradiating a common search pulse to the measurement region and the reference propagation medium .

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