JP5890358B2 - Ultrasonic image pickup apparatus and ultrasonic image display method - Google Patents

Description

  The present invention relates to an ultrasonic probe and an ultrasonic imaging apparatus, and more particularly to an ultrasonic imaging apparatus and an ultrasonic image display method for displaying an ultrasonic image.

  The ultrasonic imaging apparatus transmits an ultrasonic wave to an object from an ultrasonic probe in contact with the surface of the object, receives an ultrasonic reflected wave from the inside of the object, and is a reception signal thereof Based on the reflected echo signal, an ultrasonic image (such as a tomographic image) relating to the biological information of the part of the subject is displayed.

  The ultrasonic diagnostic apparatuses described in Patent Literatures 1 and 2 are elastic from elastic information based on displacement and strain at each measurement point inside the subject and stress at each measurement point that occur when a compression force is applied to the subject. An image is generated (see Patent Document 1 and Patent Document 2). Then, the examiner distinguishes lesions such as normal tissues, cancer cells, and tumors by observing the elastic image while adjusting the compression force.

  On the other hand, in order to acquire the elasticity information of the tissue with high accuracy, it is important to measure the stress (or stress distribution) generated inside by applying a compression force to the subject with high accuracy. However, since a normal ultrasonic diagnostic apparatus cannot directly measure stress (or stress distribution), various estimation methods for stress (or stress distribution) have been devised. For example, in the finite element method (FEM), the stress distribution is estimated by obtaining the stress distribution by assuming the boundary conditions of the subject such as the shape of the subject and the restraint state.

JP-A-5-317313 JP 2000-60853 A

  However, since the ultrasonic diagnostic apparatuses described in Patent Documents 1 and 2 do not take into consideration the conditions (shape, boundary conditions, etc.) of the subject, the subject caused by the conditions (shape, boundary conditions, etc.) of the subject. Cannot cope with changes in stress (or stress distribution) inside the specimen. In addition, in the finite element method (FEM), when the shape of the subject and the boundary state setting are different from the actual shape and boundary conditions, the stress distribution estimation accuracy decreases, and as a result, an elastic image with low reliability is generated. Will be.

  The present invention takes into account changes in the internal stress (or stress distribution) of a subject due to the conditions of the subject (shape, boundary conditions, etc.) by considering the conditions of the subject (shape, boundary conditions, etc.). An object of the present invention is to provide an ultrasonic imaging apparatus capable of measuring stress distribution with high accuracy by setting the conditions (shape, boundary conditions, etc.) of the subject with high accuracy.

  An ultrasonic imaging apparatus according to the present invention includes a pressure measurement unit that measures a pressure applied to a subject, a condition setting unit that sets a condition relating to a measurement region based on an ultrasonic image of the subject, and the pressure And a stress information calculation unit that calculates the stress information of the measurement site under the condition.

  The present invention provides an ultrasonic imaging apparatus and an ultrasonic image display method capable of measuring a stress distribution with high accuracy by setting conditions (shape, boundary conditions, etc.) of a subject with high accuracy. .

It is a block diagram which shows the ultrasonic imaging device which concerns on this Embodiment. It is a block diagram which shows an example of a structure of the stress calculating part which concerns on this Embodiment. It is a figure which shows calculating | requiring stress (sigma) or stress distribution (sigma) (x, y, z) by using the structural analysis simulation by a finite element method (FEM). It is the figure which showed the tomographic image (B mode image) and elasticity image which were produced | generated by applying compression to the breast site | part containing a mammary gland tissue. It is the figure which showed the state in which the conditions of the measurement site | part were set based on the tomographic image (B mode image). It is the figure which showed the state in which the boundary line was set between the thyroid gland (soft tissue) and the trachea (fixed tissue) based on the tomographic image (B mode image). It is the figure which showed an example of the model stored in a database. It is the figure which showed producing | generating the model suitable for the conditions of the measurement site | part by linear interpolation. It is the figure which showed the state in which the some boundary line was set based on the tomographic image (B mode image). It is the figure which showed calculating the distortion ratio in the same line based on coupler distortion and measurement point distortion. It is the figure which showed that a display part displays the selected model. It is the figure which showed that a display part displayed elasticity information and stress information. It is the figure which showed that a display part displayed the sound speed information and stress information in ROI.

  Hereinafter, an ultrasonic imaging apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an ultrasonic imaging apparatus according to the present embodiment. The ultrasonic imaging apparatus obtains a tomographic image of a diagnostic region of a subject using ultrasonic waves and displays an elastic image representing the hardness or softness of a living tissue.

  As shown in FIG. 1, a probe (ultrasonic probe) 2 used in contact with a subject 1 has a plurality of transducers that transmit and receive ultrasonic waves to and from the subject 1. The probe 2 is driven by ultrasonic pulses supplied from the transmission circuit 3. The transmission / reception control circuit 4 controls the transmission timing of the ultrasonic pulses that drive the plurality of transducers of the probe 2 and performs a process of forming an ultrasonic beam toward the focal point set in the subject 1. . In addition, the transmission / reception control circuit 4 performs a process of electronically scanning the ultrasonic beam in the arrangement direction of the transducers of the probe 2.

  The probe 2 receives a reflected echo signal generated from the subject 1 and outputs it to the receiving circuit 5. In accordance with the timing signal input from the transmission / reception control circuit 4, the reception circuit 5 takes in the reflected echo signal and performs reception processing such as amplification. The reflected echo signal processed by the reception circuit 5 is input to the phasing addition circuit 6. The phasing and adding circuit 6 amplifies the reflected echo signal by adding the phases of the reflected echo signals received by the plurality of transducers together. The reflected echo signal phased and added by the phase adjusting 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.

  The reflected echo signal processed by the signal processing unit 7 is guided to the monochrome scan converter 8 and converted into two-dimensional tomographic image data (digital data) corresponding to the scanning surface of the ultrasonic beam. The signal processing unit 7 and the black and white scan converter 8 constitute a tomographic image (B-mode image) image forming unit. The tomographic image data output from the monochrome scan converter 8 is supplied to the display unit 10 via the switching addition unit 9. The display unit 10 displays a tomographic image (B mode image) that is an ultrasonic image.

  The reflected echo signal output from the phasing addition circuit 6 is guided to the frame data acquisition unit 11. The frame data acquisition unit 11 acquires a reflected echo signal corresponding to the scanning plane (tomographic plane) of the ultrasonic beam as frame data, and stores a plurality of frame data in a storage unit such as a memory. The displacement / strain calculation unit 12 sequentially fetches a plurality of frame data stored in the frame data acquisition unit 11 at different acquisition times, and obtains the displacement or distortion of the measurement point on the tomographic plane based on the acquired pair of frame data. The obtained displacement or strain is output to the elasticity information calculation unit 13 as displacement frame data or strain frame data (displacement / strain frame data).

  The pressure measurement unit 17 measures the pressure applied from the probe 2 to the surface of the subject 1 and outputs the measured pressure to the stress calculation unit 18 as pressure data. Here, the method for obtaining the pressure of the probe 2 can be selected as appropriate, and there is a method for obtaining the surface pressure of the subject 1 using a pressure sensor, an acoustic coupler, or the like.

  The stress calculation unit 18 calculates the stress or stress distribution inside the subject 1 as stress frame data based on the pressure data, and outputs the calculated stress frame data to the elasticity information calculation unit 13.

  Based on the displacement / strain frame data and the stress frame data, the elastic information calculation unit 13 obtains elastic information such as the elastic modulus (eg, Young's modulus) of the living tissue at each measurement point as elastic frame data, and the elastic frame data is elastic. The information is output to the information processing unit 14.

  The elastic information processing unit 14 subjects the elastic frame data input from the elastic information calculation unit 13 to smoothing processing and contrast optimization processing within the coordinate plane of the elastic frame data, so that a time axis between a plurality of elastic frame data is obtained. Various image processing is performed by performing direction smoothing processing and the like, and the elastic frame data subjected to the image processing is sent to the color scan converter 15.

  The color scan converter 15 takes in elastic frame data (elastic frame data indicating elastic characteristics such as elastic modulus) processed by the elastic information processing unit 14 and assigns a color code for each pixel according to a color map corresponding to the elastic modulus. Thus, a color elastic image is generated.

  The color elasticity image (ultrasonic image) generated by the color scan converter 15 is displayed on the display unit 10 via the switching addition unit 9. Further, the switching addition unit 9 inputs the black and white tomographic image output from the black and white scan converter 8 and the color elastic image output from the color scan converter 15 and switches both images to display one of them. A display function, a function of causing one of the two images to be translucent, adding and synthesizing and superimposing them on the display unit 10, and a function of displaying both images side by side on the display unit 10. Further, the image data output from the switching addition unit 9 is stored in the cine memory 20 under the control of the device control interface unit 19. The image data stored in the cine memory 20 is displayed on the display unit 10 under the control of the device control interface unit 19.

  The stress calculation unit 18 according to the feature of the present embodiment acquires the shape of the subject 1 and the boundary conditions (restraint state, etc.) of the subject 1, and calculates the stress applied to each measurement point in consideration of those conditions. Ask.

  FIG. 2 is a block diagram showing an example of the configuration of the stress calculation unit 18 according to the present embodiment. As shown in FIG. 2, the stress calculation unit 18 includes a condition setting unit 180, a condition adjustment unit 181, a model selection unit 182, and a stress information calculation unit 184. The condition setting unit 180 sets conditions for the measurement site. The condition adjustment unit 181 adjusts the set condition. The model selection unit 182 selects from the database 183 a model for simulating the stress at the measurement site. The stress information calculation unit 184 calculates stress information (stress or stress distribution) based on the model, and generates stress frame data.

  Next, the basic operation of this embodiment will be described. First, the probe 2 presses the subject 1 and scans the subject 1 with an ultrasonic beam. The receiving circuit 5 continuously receives the reflected echo signal from the scanning plane. Based on the reflected echo signal output from the phasing addition circuit 6, the signal processing unit 7 and the monochrome scan converter 8 form a tomographic image, and the display unit 10 displays the tomographic image via the switching addition unit 9.

  The frame data acquisition unit 11 captures the reflected echo signal, repeatedly acquires the frame data in synchronization with the frame rate, and stores the frame data in a built-in storage unit (such as a frame memory) in chronological order. Then, the frame data acquisition unit 11 selects a plurality of pairs of frame data continuously with a pair of frame data having different acquisition times as one unit, and outputs the frame data to the displacement / distortion calculation unit 12. The displacement / distortion calculation unit 12 performs one-dimensional or two-dimensional correlation processing on the selected pair of frame data, measures the displacement of a plurality of measurement points on the scanning plane, and moves the displacement frame data or the distortion frame data (displacement / distortion frame data). Distortion frame data).

  As a displacement vector detection method, for example, a block matching method or a gradient method described in JP-A-5-317313 is known. In the block matching method, an image is divided into blocks of N × N pixels, for example, and a block closest to the focused block (for example, a block at a measurement point) in the current frame is searched from the previous frame. The displacement of the measurement point is obtained based on the block position, and displacement frame data is generated. Further, the displacement is calculated by calculating the autocorrelation in the same region of the paired RF signal frame data, and the displacement frame data is generated.

  Based on the displacement frame data, the distortion at each measurement point is obtained. The distortion calculation is calculated, for example, by spatially differentiating the displacement, and distortion frame data is generated.

  The pressure measurement unit 17 is applied from the probe 2 to the surface (compression surface) of the subject 1 by a pressure sensor 16 or an acoustic coupler provided between the ultrasonic transmission / reception surface of the probe 2 and the subject 1. The measured pressure is measured, and the measured pressure is output to the stress calculation unit 18 as pressure data. The stress calculation unit 18 calculates the stress or stress distribution inside the subject 1 as stress frame data based on the pressure data.

  The elasticity information calculation unit 13 obtains elasticity information of the measurement point using the displacement / strain frame data and the stress frame data. For example, the elasticity information calculation unit 13 calculates the elastic modulus (for example, Young's modulus E) of each measurement point on the scanning surface from the stress at each measurement point and the distortion obtained by the elasticity information calculation unit 13, and the elasticity frame Data is output to the elastic information processing unit 14. The elastic information processing unit 14 performs processing such as smoothing processing on the elastic frame data and outputs the processed data to the color scan converter 15. The color scan converter 15 generates a color elasticity image based on the elasticity information. For example, in a color elastic image, a color corresponding to the elastic modulus is assigned to each pixel with a gradation of color tone by 256 gradations. A black and white scan converter may be used instead of the color scan converter 15. In this case, the black and white scan converter generates a black and white elastic image based on the elasticity information. In black-and-white elastic images, the elasticity information can be visually recognized by increasing the brightness of areas with a high elastic modulus and decreasing the brightness of areas with a low elastic modulus, for example, lesions such as normal tissues, cancer cells, and tumors. Can be distinguished.

  As described above, the stress calculation unit 18 calculates the stress or stress distribution inside the subject 1 as stress frame data based on the pressure data, and the elasticity information calculation unit 13 calculates the elastic modulus (for example, Elasticity information such as Young's modulus E) is calculated. The stress calculation unit 18 obtains a stress distribution assuming the shape of the measurement site and the boundary conditions (such as restraint state), which are the conditions (shape, boundary conditions, etc.) of the subject 1, and the elasticity information calculation unit 13 performs each measurement. The elastic modulus E of the point is calculated. For example, assuming that the measurement site is an isotropic elastic body and using three equations, a balance equation, a strain-displacement relationship equation, and a stress-strain relationship equation (Hook's law), as shown in equation (1) The elastic modulus (eg, Young's modulus E) at each measurement point of the tissue is obtained from the strain εz in the z-axis direction and the stresses σx, σy, σz in the x, y, and z-axis directions. The stress distribution is a distribution of stresses σx, σy, σz in space (coordinates (x, y, z)).

E = (σz−ν (σx + σy)) / εz (ν: Poisson's ratio) (1)

  As shown in Expression (2), when (σz−ν (σx + σy)) is defined as σ, the elastic modulus (Young's modulus E) is expressed by Expression (3).

σ≡ (σz−ν (σx + σy)) (2)
E = σ / εz (3)

  As shown in FIG. 3, the stress σ or the stress distribution σ (x, y, z) can also be obtained by using a structural analysis simulation by a finite element method (FEM). Here, the compression direction is the z-axis direction. As shown in FIG. 3A, in order to obtain the stress distribution inside the subject 1, the shape of the measurement site and the boundary conditions (restraint state, etc.) are assumed.

<Measurement site conditions>
Shape: Cylindrical (Diameter: φ100 [mm], Thickness: 10, 30, and 50 [mm])
Hardness (elastic modulus): Young's modulus E = 1.0 [kPa]
Poisson's ratio: ν = 0.495
Boundary conditions: compression surface → no constraint, bottom surface → xyz direction (fixed), side surface → no constraint

  FIGS. 3B and 3C are diagrams showing the results of analyzing the stress distribution when a pressure of 1 [kPa] is applied to the compression surface in the z-axis direction. FIGS. 3B and 3C show changes in the stress distributions σz and σ in depth when the thickness of the subject 1 is changed to 10 [mm], 30 [mm], and 50 [mm]. Yes. In order to acquire the elasticity information of the tissue with high accuracy, it is important to measure the stress distributions σ and σz generated inside by applying a compression force to the subject 1 with high accuracy. Since a normal ultrasonic diagnostic apparatus cannot directly measure stress (or stress distribution), the stress distributions σ and σz are estimated by setting the measurement site conditions as described above. The stress distributions σ and σz vary greatly depending on the set conditions (such as the shape of the subject 1 and boundary conditions). That is, the estimation results of the stress distributions σ and σz depend on the set conditions.

  For example, as shown in FIGS. 3B and 3C, the estimation results of the stress distributions σ and σz depend on the shape (thickness) of the set measurement site. In addition, when “restraint (fixed) in xyz direction” which is a boundary condition (constraint condition) of the bottom surface is changed to “unconstrained”, the stress distributions σ and σz largely change particularly near the bottom surface. The ultrasonic imaging apparatus according to the present embodiment can measure the stress or the stress distribution with high accuracy by accurately setting the shape of the measurement site and the boundary condition.

  Next, it will be described that the ultrasonic imaging apparatus according to the present embodiment sets the shape of the measurement site and the boundary conditions. FIG. 4 is a view showing a tomographic image (B-mode image) and an elasticity image generated by applying pressure to a breast part including a mammary gland tissue. As shown in FIG. 4, from the contact surface 41 where the probe 2 is in contact with the subject 1 to the deepest rib, fat, mammary gland, tumor, great pectoral muscle, and rib are tomographic images (B-mode image). 40. In the present embodiment, the elastic modulus (Young's modulus E) at the measurement point in each part of the living tissue is obtained as elastic information.

  The condition setting unit 180 sets conditions for the measurement site. FIG. 5 is a diagram showing a state in which the measurement site condition is set based on the tomographic image (B-mode image) 40. As shown in FIG. 5, the condition setting unit 180 sets the conditions (shape, boundary conditions, etc.) of the measurement site based on the tomographic image (B mode image) 40 displayed on the display unit 10. For example, as shown in FIG. 5, the distance (thickness) of the soft tissue portion (from fat to the pectoralis major muscle) that is easily deformed by compression is about 30 mm, and the hard tissue (rib) that is difficult to deform by compression is It is a bottom surface (support surface) that supports soft tissue, and is restrained (fixed) in the xyz direction.

  In this case, the condition setting unit 180 refers to a model (stereoscopic model) described later, such as a boundary (boundary line or boundary surface), a boundary condition, a shape (including size) of a measurement site, and a compression position. Set the measurement site conditions. For example, based on the tomographic image (B-mode image) 40, a boundary line 50 is set at the boundary between the great pectoral muscle that is a soft tissue and the rib that is a hard tissue, and the distance from the contact surface 41 to the boundary line (rib) 50 ( Approx. 30 [mm]) is measured, and the boundary condition between the upper surface (contact surface 41), the bottom surface (the surface in the y direction passing through the boundary line 50) and the side surface (the surface in the z direction or the compression direction sandwiched between the bottom surface and the upper surface) Are set as “compression surface (contact surface 41) → no constraint, bottom surface → constraint (fixed) in xyz direction, side surface (z direction or surface in the compression direction) → unconstrained”. Here, the reason why the boundary line 50 (or the boundary surface) is set between the soft tissue and the hard tissue is that the hard tissue has a small deformation due to the compression and generally has a small movement due to the compression.

  The boundary condition is set according to the characteristics of each surface (upper surface, bottom surface, and side surface). For example, the boundary conditions of the bottom surface are “bottom → constrained (fixed) in xy direction, unconstrained in z direction (free)”, “bottom → unconstrained in xy direction (free), constrained in z direction (fixed)”, etc. It is set according to the characteristics of the bottom surface. Depending on the characteristics of each surface (upper surface, bottom surface, and side surface), the characteristics of each surface may be visually identified by changing the lines that define each surface and the display of the surface. For example, the characteristics of the boundary line 50 (or boundary surface) (color, shape, thickness, etc. of the line or dotted line) change according to the characteristics of the bottom surface. For example, the boundary condition is “restrained in the bottom surface → xyz direction”. In the case of (fixed) ", the color of the boundary line 50 (or boundary surface) may change to red. In addition, characters representing boundary conditions (for example, “restraint (fixed) in bottom surface → xyz direction”), symbols, figures, and the like may be attached according to the characteristics of each surface.

  In addition, the condition setting unit 180 can set the boundary line 50 on the side surface instead of the bottom surface. FIG. 6 is a diagram showing a state in which a boundary line 50 is set between the thyroid gland (soft tissue) and the trachea (fixed tissue) based on the tomographic image (B-mode image) 40. Here, the reason why the boundary line 50 (or the boundary surface) is set between the soft tissue and the fixed tissue is that the fixed tissue hardly moves due to the compression. Soft tissue can be deformed up to fixed tissue and does not deform beyond fixed tissue. That is, the boundary line 50 (or boundary surface) between the thyroid gland (soft tissue) and the trachea (fixed tissue) is fixed in the x-axis direction. In this case, the condition setting unit 180 sets “restraint (fixed) in side surface (z direction or compression direction surface) → x axis direction” as the boundary condition.

  As shown in FIG. 6, the condition setting unit 180 can also set a curve as the boundary line 50. For example, the condition setting unit 180 sets the boundary line 50 along the curved surface of the trachea. The boundary line 50 (or boundary surface) between the thyroid gland (soft tissue) and the trachea (fixed tissue) is fixed in the normal direction of the boundary line 50. In this case, the condition setting unit 180 sets “restraint (fixed) in side surface (curved surface) → normal direction” as the boundary condition.

  Further, the condition setting unit 180 can set the boundary line 50 on the upper surface (contact surface 41). The boundary condition of the upper surface (contact surface 41) varies depending on whether the shape of the probe 2 is linear or convex. Further, the boundary condition of the upper surface (contact surface 41) changes depending on the curvature of the contact surface of the probe 2. Accordingly, the boundary line 50 is set according to the boundary condition (shape) of the upper surface (contact surface 41).

  The boundary line 50 can be input as an elastic image instead of the tomographic image (B-mode image) 40.

  In addition, the condition setting unit 181 may adjust the set condition. The condition adjustment unit 181 adjusts (changes, moves, rotates) boundary conditions such as the boundary line 50 on the ultrasonic image (tomographic image or elastic image) in accordance with an input from the device control interface unit 19 such as a trackball or a mouse. Zoom in and out). For example, as shown in FIG. 5, the condition adjustment unit 181 may adjust the angle of the boundary line 50 set horizontally and the distance from the contact surface 41. Moreover, as shown in FIG. 6, the condition adjustment part 181 may adjust the shape of the boundary line 50 so that the boundary line 50 may follow the curved surface of a trachea.

  The model selection unit 182 is a model corresponding to the conditions (boundary conditions and the like) set by the condition setting unit 180 or adjusted by the condition adjustment unit 181, and a model for simulating stress at the measurement site is stored in the database 183. select. That is, the model selection unit 182 reads from the database 183 a model (stress distribution template) that matches the set measurement site conditions.

  The database 183 stores a plurality of models according to the characteristics of the measurement site. For example, as shown in FIG. 7, the database 183 has various shapes (such as a cylindrical shape and a quadrangular prism shape), sizes, and positions (such as a bottom surface, a side surface, and a central portion) of a support (such as a hard tissue or a fixed tissue). , And a model that combines the size, position, and direction of the compression surface. When the measurement site is the breast, a cylindrical model shown in FIG. 7A is suitable. In addition, when the measurement site is a foot (such as rectus femoris) or an arm (such as pronation muscle), the models shown in FIGS. 7C and 7D are suitable. A plurality of models are stored in the database 183 in units of 1 mm.

  For example, as shown in FIG. 5, the conditions of the measurement region set by the condition setting unit 180 are “shape: cylindrical shape (diameter: φ100 [mm], thickness: 30 [mm])”, “hardness (elasticity). Ratio): Young's modulus E = 1.0 [kPa] ”,“ Poisson's ratio: ν = 0.495 ”, and“ boundary conditions: compression surface → no constraint, bottom surface → constrained in xyz direction (fixed), side surface → constraint In the case of “none”, the database 183 selects a cylindrical model (for example, the model of FIG. 7A) that meets the set condition, and selects stress characteristic information (for example, stress distribution σTx) of the selected model. (I, j), σTy (i, j), σTz (i, j) or stress distribution σT (i, j)) is read from the database 183. The stress distributions σTx (i, j), σTy (i, j), and σTz (i, j) are stress distributions in the x, y, and z axis directions simulated in advance in each model, and the coordinates (i: x axis) (Direction coordinates, j: coordinates in the z-axis direction). The stress distribution σT (i, j) is expressed by Expression (4).

σT≡ (σTz−ν (σTx + σTy)) (4)

  The stress calculation unit 18 may calculate stress information by a structural analysis simulation of a finite element method (FEM) using a model for simulating the stress at the measurement site. Although FIG. 3 shows the stress distribution σ in the center line, the stress distribution σT at the coordinates (i, j) can be calculated by simulating the stress distribution of all lines by the finite element method (FEM). Further, the stress distribution of the model (stress distribution template) may be calculated in advance and stored in the database 183 by using another analysis method instead of the finite element method (FEM).

  The stress distributions σTx, σTy, σTz, and σT in the model (stress distribution template) are stress distributions that are generated when a pressure of 1 [Pa] is uniformly applied to the compression surface, and are standardized stress distributions. Therefore, the stress distribution when the pressure P [Pa] is applied to the compression surface is calculated by multiplying the stress distributions σTx, σTy, σTz, σT of the model (stress distribution template) by P.

  That is, as shown in Expression (5) or Expression (6), the stress information calculation unit 184 calculates stress information based on the model, and generates stress frame data.

σz (i, j) = P × σTz (i, j) (5)
σ (i, j) = P × σT (i, j) (6)

  Further, instead of the stress distribution generated when a pressure of 1 [Pa] is uniformly applied to the compression surface, the stress distribution is calculated in advance based on the pressure distribution P (i, j) [Pa] on the compression surface, It may be stored in the database 183.

  The stress calculation unit 18 calculates the stress or stress distribution inside the subject 1 as stress frame data based on the pressure data P, and outputs the calculated stress frame data to the elasticity information calculation unit 13.

  The elasticity information calculation unit 13 inputs the displacement frame data D (i, j), the strain frame data εz (i, j), and the stress frame data σz (i, j), σ (i, j), and the equation ( 7), the elastic frame data E (i, j) of the elastic information (such as Young's modulus E) is obtained, and the elastic frame data E (i, j) is output to the elastic information processing unit 14.

E (i, j) = σ (i, j) / εz (i, j) (7)

  The output elastic frame data E (i, j) is displayed on the display unit 10 as a color elastic image (ultrasonic image) via the elastic information processing unit 14, the color scan converter 15, and the switching addition unit 9. .

  As described above, the ultrasonic imaging apparatus according to the present embodiment takes into account the subject caused by the condition of the subject (shape, boundary condition, etc.) by considering the condition of the subject (shape, boundary condition, etc.). It is possible to cope with changes in the stress (or stress distribution) inside the specimen, and the stress distribution can be measured with high precision by setting the conditions (shape, boundary conditions, etc.) of the specimen with high precision. In the ultrasonic image display method according to the present embodiment, the pressure applied to the subject is measured, the condition relating to the measurement region is set based on the ultrasonic image of the subject, and the pressure is applied based on the pressure. The stress information of the measurement site under conditions is calculated.

  As mentioned above, although embodiment concerning this invention was described, this invention is not limited to these, It can change and deform | transform within the range described in the claim.

  In FIG. 7, the model selection unit 182 selects a model (stress distribution template) from the database 183. In this case, the model selection unit 182 may generate a model (stress distribution template) that matches the conditions of the measurement site by selecting a plurality of models and using linear interpolation or the like. For example, when a cylindrical model having a thickness of 25 [mm] is generated, the stress σ (10 mm) of the cylindrical model having a thickness of 10 [mm] and a cylindrical shape are obtained as shown in FIG. The model selection unit 182 may generate a model adapted to the conditions of the measurement site by linearly complementing the stress σ (30 mm) of the model having a thickness of 30 [mm] with a weight of 1/4: 3/4. .

σz (25 mm) = σz (10 mm) × 1/4 + σz (30 mm) × 3/4
(8)

  As described above, the model selection unit 182 can generate a model (stress distribution template) that matches the conditions of the measurement site by combining a plurality of models.

  In addition, the condition setting unit 180 sets the boundary line 50 (or boundary surface) as a condition of the measurement region in order to refer to the model (stereoscopic model). In this case, the condition setting unit 180 may set a plurality of boundary lines (or boundary surfaces). FIG. 9 is a diagram illustrating a state in which a plurality of boundary lines are set based on the tomographic image (B-mode image) 40. As shown in FIG. 9, in addition to the boundary line 50 at the boundary between the great pectoral muscle that is a soft tissue and the rib that is a hard tissue, the boundary line 51, at each boundary also in the soft tissue (fat, mammary gland, and great pectoral muscle) 52 is set. When there is a specific part (target part) such as a tumor, a boundary line 53 may be set at the boundary of the specific part (target part). Even in a soft tissue, fat, mammary gland, and greater pectoral muscle have different stress characteristics. Therefore, by setting boundary lines 50, 51, 52, and 53 at the respective boundaries, more accurate stress information or elastic information. Can be obtained. It is also possible to set boundary conditions for a plurality of boundary lines 50, 51, 52, and 53, respectively. The model selection unit 182 selects a plurality of models from the database 183 based on the set boundary lines 50, 51, 52, and 53, and combines the plurality of models so that the model ( Stress distribution template) can be generated.

  The elastic information calculation unit 13 calculates an elastic modulus (for example, Young's modulus E), but may calculate a strain ratio as elastic information. In this case, the elastic information calculation unit 13 generates strain ratio frame data SR (i, j) instead of the elastic frame data E (i, j) of the elastic modulus (Young's modulus E), and the display unit 10 The strain ratio image is displayed as an elastic image.

  For example, in the case of a two-dimensional frame, as shown in FIG. 10, the coupler distortion in the acoustic coupler in the line (i: coordinate in the x-axis direction) is “ε0 (i)”, and the displacement / distortion calculation unit 12 Assuming that the measurement point distortion of the measurement site calculated by the above equation is “ε (i, j)”, the distortion ratio SR (i, j) in the same line is expressed by Expression (9).

SR (i, j) = ε0 (i) / ε (i, j) (9)

  However, as the depth in the depth direction (z-axis direction) increases due to the effect of stress attenuation, the strain ratio SR (i, j) at the measurement site decreases.

  Therefore, the stress information calculation unit 184 calculates the stress attenuation rate σa using the stress distribution σT (i, j) of the model (stress distribution template). For example, the attenuation rate σa of the stress σT at the depth (j: coordinate in the z-axis direction) of each line (i: coordinate in the x-axis direction) is an expression for the stress σT (i, 0) at the depth 0 (zero). It is represented by (10).

σa (i, j) = σT (i, 0) / σT (i, j) (10)

  The elastic information calculation unit 13 calculates a corrected strain ratio SR ′ (i, j) from which the influence of stress attenuation is removed, based on the attenuation rate σa, as shown in Expression (11).

SR ′ (i, j) = (ε0 (i) / ε (i, j)) / σa (i, j)
(11)

  A distortion ratio image (elastic image) is obtained by gradationizing and displaying the value of the corrected distortion ratio SR ′ (i, j). The elastic information processing unit 14 performs image processing on the elastic frame data having the corrected strain ratio SR ′, and the color scan converter 15 takes in the elastic frame data (elastic frame data indicating the elastic characteristics of the corrected strain ratio SR ′). Then, according to a color map corresponding to the distortion ratio SR ′, a color elasticity code is generated for each pixel to generate a color elastic image, and the display unit 10 displays the distortion ratio image.

  In this way, a strain ratio image (elastic image) is generated based on the corrected strain ratio SR ′ from which the influence of stress attenuation has been removed, and the elasticity information of the measurement site (region of interest of the subject 1) is evaluated with high accuracy. It becomes possible.

  The distortion of the acoustic coupler is obtained based on the distortion frame data obtained by the displacement / distortion calculation unit 12. The distortion of the acoustic coupler may be obtained based on a change in the thickness of the acoustic coupler obtained from the coordinates of the boundary between the acoustic coupler and the subject 1.

  The condition setting unit 180 may set a measurement site condition (at least one of a boundary and a boundary condition) based on the luminance of the ultrasonic image.

  When the measurement site is soft tissue, the soft tissue is supported by hard tissue such as bone. For example, if the subject 1 is the breast (soft tissue), the ribs support the breast, and if the subject 1 is the rectus femoris (soft tissue), the femur is supported. Therefore, the condition setting unit 180 sets the boundary between the soft tissue and the hard tissue as a boundary line (or boundary surface).

  Ultrasonic waves have a characteristic that they are reflected more strongly at boundaries where the acoustic impedance changes greatly. Since the acoustic impedance of soft tissue and hard tissue (such as bone) is greatly different, the acoustic impedance changes greatly at the boundary between the soft tissue and the hard tissue. Accordingly, the boundary between the soft tissue and the hard tissue is displayed with high luminance on the tomographic image (B-mode image), and the echo is attenuated at a site deep in the boundary (inside the hard tissue), so that the inside of the hard tissue has low luminance. . The condition setting unit 180 detects boundary coordinates between the soft tissue and the hard tissue based on the luminance (including luminance change) of the ultrasonic image, and sets the boundary between the soft tissue and the hard tissue as a boundary line (or boundary surface). For example, the condition setting unit 180 detects boundary coordinates of a portion (in the hard tissue) having a luminance lower than a predetermined threshold, and sets the boundary coordinates (or boundary surface) based on the boundary coordinates. In addition, the condition setting unit 180 sets the distance between the set boundary line (or boundary surface) and the contact surface 41 as the shape (thickness) of the measurement site.

  The condition setting unit 180 may set conditions (shape, boundary conditions, etc.) of the measurement part based on at least one of the displacement and distortion of the measurement part.

  Since soft tissue and hard tissue are different in hardness, displacement or strain (for example, strain εz (i, j) in the z-axis direction) changes at the boundary between soft tissue and hard tissue. For example, since bone is significantly harder than soft tissue, the magnitude of strain εz (i, j) rapidly decreases at the boundary between bone and soft tissue. The condition setting unit 180 detects the boundary coordinates between the soft tissue and the hard tissue based on the displacement or distortion (including change of the displacement or distortion) of the ultrasonic image, and sets the boundary between the soft tissue and the hard tissue as a boundary line (or boundary surface). ). For example, the condition setting unit 180 detects boundary coordinates of a portion (inside hard tissue) having a displacement or distortion smaller than a predetermined threshold, and sets the boundary coordinates (or boundary surface) based on the boundary coordinates. In addition, the condition setting unit 180 detects boundary coordinates of a portion (inside the hard tissue) having a strain change rate in the z-axis direction that is larger than a predetermined threshold, and uses the boundary coordinates (or boundary surface) as the boundary coordinates. Set. The condition setting unit 180 sets the distance between the set boundary line (or boundary surface) and the contact surface 41 as the shape (thickness) of the measurement site.

  In addition, the condition setting unit 180 may set a boundary condition based on at least one of displacement and distortion of the measurement site of the ultrasonic image. The condition setting unit 180 may set the boundary condition of the measurement region based on at least one of displacement and distortion in the boundary direction (boundary line direction or boundary surface direction) of the measurement region.

  For example, when the boundary has a displacement or distortion in the boundary direction smaller than a predetermined threshold, the condition setting unit 180 performs “boundary is constrained in xyz direction (fixed)” or “boundary is constrained in x direction (fixed)”. If the boundary has a displacement or distortion in the boundary direction larger than a predetermined threshold value, “boundary is unconstrained in xyz direction (free)” or “boundary is unconstrained in x direction (free)” is set.

  In addition, when the direction of the boundary line is the x-axis direction, the condition setting unit 180 evaluates the distortion εx (i, jb) in the x-axis direction at the boundary coordinates (j = jb). Set the condition (restraint state). In this case, the condition setting unit 180 obtains the ratio (Poisson's ratio ν) of the strain εz (i, jb) in the z-axis direction and the strain εx (i, jb) in the x-axis direction as shown in Expression (12). The boundary condition may be set based on the ratio (Poisson's ratio ν).

Poisson's ratio ν (i, jb) = − εx (i, jb) / εz (i, jb)
(12)

  When the Poisson's ratio ν (i, jb) is sufficiently large (greater than a predetermined threshold value) at the boundary coordinates (j = jb), the x-axis direction is larger than the longitudinal strain εz (i, jb) in the z-axis direction. This means that the lateral distortion −εx (i, jb) of the condition setting unit 180 is sufficiently large, and the condition setting unit 180 determines that “the boundary is unconstrained in the xyz direction (free)” or “the boundary is unconstrained in the x direction (free)”. Set. On the other hand, when the Poisson's ratio ν (i, jb) is close to 0 (zero) (less than a predetermined threshold), the condition setting unit 180 determines that “the boundary is constrained (fixed) in the xyz direction” or “the boundary is x Set “Restrain (fixed) by direction”.

  In addition, when the direction of the boundary line is the x-axis direction, the condition setting unit 180 evaluates the displacement Dx (i, jb) in the x-axis direction at the boundary coordinates (j = jb). Set the condition (restraint state). In this case, the condition setting unit 180 may obtain a plurality of displacements across the boundary, and set a boundary condition based on the displacements across the boundary. For example, as shown in Expression (13) and Expression (14), the condition setting unit 180 includes two locations (inside and outside of the hard tissue) above and below the boundary coordinates (j = jb) between the hard tissue (such as bone) and the soft tissue ( The displacements Dx (i, jb-1) and Dx (i, jb + 1) in the x-axis direction at the measurement points i, jb-1) and (i, jb + 1) are obtained, and the boundary is determined based on the displacement ratio D1 or difference D2. Conditions may be set.

D1 = Dx (i, jb-1) / Dx (i, jb + 1) (13)
D2 = Dx (i, jb-1) -Dx (i, jb + 1) (14)

  The condition setting unit 180 evaluates the displacement ratio D1 or the difference D2 to determine whether the plurality of places moved in the same direction or the plurality of places moved in the reverse direction as the interlinkage between the plurality of places across the boundary. It is possible to evaluate how much the difference in the movement of the parts is. That is, the condition setting unit 180 can evaluate the displacement near the boundary (for example, above and below the boundary or inside and outside the hard tissue) by evaluating the displacement ratio D1 or the difference D2. For example, when the displacement in the x-axis direction is large (when the displacement ratio D1 or the difference D2 is larger than a predetermined threshold value), the condition setting unit 180 determines that “the boundary is unconstrained in the xyz direction (free)” or “the boundary is Set "No constraint (free) in x direction". On the other hand, when the displacement in the x-axis direction is close to 0 (zero) (when the displacement ratio D1 or the difference D2 is smaller than a predetermined threshold value), the condition setting unit 180 determines that “the boundary is constrained (fixed) in the xyz direction”. Or, “boundary is restricted in x direction (fixed)” is set.

  The condition setting unit 180 also measures a plurality of locations (a1 ≦ i ≦ a2, b1 ≦ j ≦ b2) above and below (inside and outside of the hard tissue) the boundary coordinates (j = jb) between the hard tissue (such as bone) and the soft tissue. The x-axis direction displacement Dx (a1 ≦ i ≦ a2, b1 ≦ j ≦ b2) at the point may be obtained, and the boundary condition may be set based on the statistical variation (dispersion, standard deviation, etc.) of the displacement. That is, the condition setting unit 180 may obtain a plurality of displacements across the boundary and set the boundary condition based on the displacements across the boundary.

  The condition setting unit 180 is in the vicinity of the displacement Dx (i, jb) in the x-axis direction (a1 ≦ i ≦ a2, b1 ≦ jb ≦ b2) at the boundary coordinates (j = jb) between the hard tissue (such as bone) and the soft tissue. By evaluating the local variation, it is possible to identify the boundary condition (restraint state) in the vicinity of the boundary coordinates (j = jb). For example, the condition setting unit 180 uses a 5 × 5 local region (i−2) as a local region centered on the boundary coordinate (j = jb) at the measurement point of the boundary coordinate (j = jb) between the hard tissue and the soft tissue. ≦ i ≦ i + 2, jb-2 ≦ jb ≦ jb + 2), and the standard deviation of the displacement Dx (i−2 ≦ i ≦ i + 2, jb−2 ≦ jb ≦ jb + 2) in the x-axis direction at the 25 measurement points Ask for. If the standard deviation of the displacement Dx in the x-axis direction (i−2 ≦ i ≦ i + 2, jb−2 ≦ jb ≦ jb + 2) is large (greater than a predetermined threshold), the condition setting unit 180 determines that “the boundary is in the xyz direction. Is set to "No constraint (free)" or "Boundary is not constraint in the x direction (free)". On the other hand, when the standard deviation of the displacement Dx (i−2 ≦ i ≦ i + 2, jb−2 ≦ jb ≦ jb + 2) is close to 0 (less than a predetermined threshold value), the condition setting unit 180 determines “boundary Is “constrained (fixed) in xyz direction” or “boundary is constrained (fixed) in x direction”.

  As described above, the condition setting unit 180 sets the boundary condition of the measurement part based on at least one of the ratio, difference, and variation of the displacements at a plurality of positions sandwiching the boundary of the measurement part.

  FIG. 11 is a diagram illustrating that the display unit 10 displays the selected model. When a model (stress distribution template) is selected, a model for simulating stress at the measurement site is stored in the database 183 in advance. Also, when using the finite element method (FEM), a model for simulating the stress at the measurement site is required. The display unit 10 displays the model 60 selected from the database 183 or the model 60 used for the finite element method (FEM). The display unit 10 may be constructed by designing the model 60 as an icon and displaying the model together with the tomographic image (B-mode image) or the elasticity image.

  The model selection unit 182 may select a model from the database 183 based on a body mark representing the positional relationship between the subject 1 and the probe 2. The body mark may be a three-dimensional solid body mark created from the volume data of the measurement site. Since the body mark schematically represents the measurement site, the type and shape of the measurement site can be grasped from the body mark. The body mark is stored in the database in association with the ultrasonic image of the measurement site. A body mark corresponding to the measurement site of the subject 1 is associated with the model and stored in the database. For example, a body mark for a mammary gland is associated with the model for the mammary gland and stored in the database in the breast, and a body mark for the thyroid gland is associated with the model for the thyroid gland and stored in the database. In order to record the cross-sectional position of the tomographic image acquired by the probe 2, the arrangement (position, angle, etc.) of the probe 2 is recorded on the body mark. The model selection unit 182 selects the shape of the model from the body mark corresponding to the measurement site, and selects the arrangement of the compression surface (such as the size, position, and direction of the compression surface) from the arrangement of the probe 2.

  The model selection unit 182 may select a model from the database 183 based on volume data corresponding to the positional relationship between the subject 1 and the probe 2. In recent years, the position information of the probe 2 is detected in real time by a technique such as RVS (Real-time Virtual Sonography), and a CT image or an MRI image corresponding to the cross-sectional position of the tomographic image observed in the ultrasonic image Is constructed from volume data as a three-dimensional solid body mark. The model selection unit 182 selects the shape of the model corresponding to the measurement site based on the body mark constructed from the volume data of the subject 1 corresponding to the cross-sectional position of the ultrasound image, and arranges the probe 2. Select the placement of the compression surface (such as the size, position and direction of the compression surface).

  The condition setting unit 180 tracks (tracks) the boundary coordinates (boundary line or boundary surface coordinates) of the measurement site, and the stress information calculation unit 184 calculates real-time stress information based on the tracked boundary coordinates. Generate stress frame data in real time. As described above, the condition setting unit 180 sets a boundary between the soft tissue and the hard tissue at the measurement site. Since the elasticity information is obtained by compressing the subject 1, the distance from the contact surface where the probe 2 contacts the subject 1 to the boundary of the measurement site becomes shorter or longer depending on the amount of compression. And even during the measurement of stress information. The condition setting unit 180 detects boundary coordinates, tracks and follows the boundary coordinates at an arbitrary time, and the stress information calculation unit 184 constructs stress frame data corresponding to the boundary coordinates in real time. For example, in a very soft tissue such as a breast, the distance from the contact surface of the probe 2 to the boundary (hard tissue such as a rib) greatly changes due to increase or decrease in the amount of compression. It is effective to build the stress frame data in real time.

The stress information calculation unit 184 may calculate the stress information by calculating its own weight based on the model. The greater the thickness of the measurement site, the greater the effect of the initial stress due to the weight of the measurement site between the shallower part near the compression surface and the deeper part of the compression surface, and the greater the depth, the greater the initial stress due to the measurement site's own weight. Become. When the specific gravity of the subject 1 is 1 g / cm ³ , for example, an initial stress (σz0 = 3 gf / cm ² ) in the z-axis direction is applied to the bottom surface (xz plane) of the measurement site having a thickness of 30 [mm]. Yes. Therefore, the stress information calculation unit 184 calculates the stress information by calculating the own weight (initial stress) of the measurement site based on the model having a thickness of 30 [mm]. The stress information calculation unit 184 can also calculate the stress information by calculating the own weight (initial stress) of the measurement site at an arbitrary depth. Thus, by considering the initial stress due to the weight of the measurement part in the calculation of the stress information at the measurement point, it is possible to measure a more accurate stress distribution.

  FIG. 12 is a diagram showing that the display unit 10 displays elasticity information and stress information. As shown in FIG. 12, an ROI (region of interest) is set in the image area of the tomographic image 40, and the display unit 10 displays the elastic information and stress information in the ROI in the information display area 61. In FIG. 12, the display unit 10 displays in the information display area 61 the relationship between the elastic information and the stress information in the ROI at each time (each frame) acquired by changing the strength of compression over time. When the display unit 10 displays the relationship between the elastic information and the stress in the information display area 61, the elastic characteristics of the tissue in the ROI can be analyzed in detail. In FIG. 12, the ROI is set for the tomographic image (B-mode image) 40, but the ROI may be set for the elastic image.

  The values plotted in the information display area 61 are approximated by an approximate function (for example, a linear function y = ax + b), and the display unit 10 displays values representing an approximate line (such as slope: a and y intercept: b). It may be displayed. The approximate function is not limited to a linear function, and may be any function that appropriately evaluates the characteristics of the plotted values.

  FIG. 13 is a diagram showing that the display unit 10 displays sound speed information and stress information in the ROI. As shown in FIG. 13, dynamic elastography (SSI, ARFI, etc.) is constructed and displayed as elastic information, such as the acoustic velocity of a shear wave (shear elastic wave) propagating through the tissue by compressing the target tissue with radiation pressure. , The display unit 10 displays the elasticity information (including the shear wave velocity) and the stress information of the tissue in the ROI in the information display area 61. In FIG. 13, the information display area 61 shows the relationship between the elastic information (including the shear wave velocity) in the ROI and the stress information at each time (each frame) acquired by the display unit 10 by changing the strength of the compression with time. Is displayed. When the display unit 10 displays the relationship between the elastic information and the stress in the information display area 61, the elastic characteristics of the tissue in the ROI can be analyzed in detail.

  The condition setting unit 180 may set the boundary of the set ROI as the condition.

  The present invention is capable of measuring stress distribution with high accuracy by setting the conditions (shape, boundary conditions, etc.) of a subject with high accuracy, and an ultrasonic imaging apparatus for displaying an ultrasonic image. It is useful as an ultrasonic image display method.

DESCRIPTION OF SYMBOLS 2 Probe 3 Transmission circuit 4 Transmission / reception control circuit 5 Reception circuit 6 Phased addition circuit 7 Signal processing part 8 Black and white scan converter 9 Switching addition part 10 Display part 11 Frame data acquisition part 12 Displacement / distortion calculation part 13 Elastic information calculation part 14 Elastic information processing unit 15 Color scan converter 16 Pressure sensor 17 Pressure measurement unit 18 Stress calculation unit 19 Device control interface unit 20 Cine memory 61 Information display area 180 Condition setting unit 181 Condition adjustment unit 182 Model selection unit 183 Database 184 Stress information calculation unit

Claims (11)

A pressure measurement unit that measures the pressure applied to the subject;
A condition setting unit for setting a condition relating to a measurement site based on an ultrasonic image of the subject;
An ultrasound image capturing apparatus comprising: a stress information calculation unit that calculates stress information of the measurement site under the condition based on the pressure ;
The ultrasonic imaging apparatus, wherein the condition setting unit sets at least one of the boundary of the condition and the boundary condition based on at least one of displacement and distortion of the measurement site. A pressure measurement unit that measures the pressure applied to the subject;
A condition setting unit for setting a condition relating to a measurement site based on an ultrasonic image of the subject;
An ultrasound image capturing apparatus comprising: a stress information calculation unit that calculates stress information of the measurement site under the condition based on the pressure;
The ultrasonic imaging apparatus according to claim 1, wherein the condition setting unit sets at least one of a boundary and a boundary condition between the soft tissue and the hard tissue of the measurement site. A pressure measurement unit that measures the pressure applied to the subject;
A condition setting unit for setting a condition relating to a measurement site based on an ultrasonic image of the subject;
An ultrasound image capturing apparatus comprising: a stress information calculation unit that calculates stress information of the measurement site under the condition based on the pressure;
The ultrasonic imaging apparatus, wherein the condition setting unit sets a boundary condition of the measurement part based on a plurality of displacements sandwiching the boundary of the measurement part. The ultrasound image capturing apparatus according to claim 3, wherein the condition setting unit sets a boundary condition of the measurement site based on at least one of a displacement ratio, a difference, and a variation at the plurality of locations. . A pressure measurement unit that measures the pressure applied to the subject;
A condition setting unit for setting a condition relating to a measurement site based on an ultrasonic image of the subject;
An ultrasound image capturing apparatus comprising: a stress information calculation unit that calculates stress information of the measurement site under the condition based on the pressure;
A model for simulating stress at the measurement site, comprising a model selection unit that selects a model corresponding to the condition from a database,
The ultrasonic image imaging apparatus, wherein the stress information calculation unit calculates stress information of the measurement site based on the model. The ultrasonic image imaging apparatus according to claim 5, wherein the model selection unit selects the model from the database based on a body mark indicating a positional relationship between the subject and the probe. The model selection unit selects the model from the database based on the body mark constructed from volume data of the subject corresponding to a cross-sectional position of the ultrasonic image. The ultrasonic imaging apparatus described. A pressure measurement unit that measures the pressure applied to the subject;
A condition setting unit for setting a condition relating to a measurement site based on an ultrasonic image of the subject;
An ultrasound image capturing apparatus comprising: a stress information calculation unit that calculates stress information of the measurement site under the condition based on the pressure;
The condition setting unit tracks a boundary of the measurement site,
The ultrasonic image capturing apparatus, wherein the stress information calculation unit calculates real-time stress information based on a tracked boundary. The ultrasonic image capturing apparatus according to claim 5, wherein the stress information calculation unit calculates the stress information by calculating a weight of the measurement site based on the model. A display unit for displaying the ultrasonic image;
The ultrasonic image capturing apparatus according to claim 1, wherein the display unit displays elasticity information and stress information in the ROI set in the ultrasonic image. A pressure measurement unit that measures the pressure applied to the subject;
A condition setting unit for setting a condition relating to a measurement site based on an ultrasonic image of the subject;
An ultrasound image capturing apparatus comprising: a stress information calculation unit that calculates stress information of the measurement site under the condition based on the pressure;
The ultrasonic imaging apparatus, wherein the condition setting unit sets an ROI boundary set in the ultrasonic image as the condition.

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