Ultrasound diagnostic device capable of changing sound speed in local region

Abstract

To provide an ultrasound diagnostic device capable of changing the sound speed in a local region.SOLUTION: An ultrasound diagnostic device 100 generates an ultrasound image 144 based on echo signals 142 from a subject BD. The ultrasound diagnostic device 100 includes an ultrasonic probe 110 that receives the echo signals 142, an interface that allows an operator to designate position information of a local region of the ultrasound image, and signal processing means 120 that changes the sound speed in the local region based on the position information when reconstructing the echo signals 142 and reconstructing the ultrasound image 144, so that the sound speed is different from the sound speed in regions other than the local region. Here, the local region is local in both the azimuth direction (X) and the depth direction (Y).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an ultrasound diagnostic device that adjusts a sound velocity value in a specific local region to display a sound velocity-adjusted ultrasound image. In particular, the ultrasound diagnostic device adjusts the sound velocity value in the specific local region to be different from the sound velocity value outside the specific local region to display a sound velocity-adjusted ultrasound image. [Background technology]

[0002] The ultrasound diagnostic device transmits ultrasound waves from an ultrasound probe equipped with multiple ultrasound transducers toward the biological tissue of a subject. The ultrasound echo signals are received by the multiple ultrasound transducers of the ultrasound probe, and an ultrasound image is created based on the received echo signals.

[0003] The echo signals received at each of the ultrasonic transducers are input to a receive beamformer, which performs receive beamforming on the echo signals received at each of the ultrasonic transducers. This receive beamforming includes a delay-and-sum process that delays and sums the echo signals received at each of the ultrasonic transducers.

[0004] The delay time in the receive beamforming is set assuming that the sound speed of the ultrasonic waves in the biological tissue is a predetermined value (for example, 1530 m / s). However, the sound speed value of the ultrasonic waves in the biological tissue may differ for each subject or each part. For example, the sound speed in the muscle may be 1590 m / s, and the sound speed in the bone may be 3000 m / s. If the sound speed value set in determining the delay time is different from the actual sound speed value, the reception focus may deteriorate. If the sound speed value set in determining the delay time is different from the actual sound speed value, the spatial resolution deteriorates and a preferable contrast cannot be obtained.

[0005] In relation to such a problem, Japanese Patent Application Laid-Open No. 8-308832 provides an ultrasonic diagnostic device that displays patterns according to different diagnostic sites of a subject and according to the layered tissue structures of the diagnostic sites, and allows the examiner to manually change the sound speed of the ultrasonic signal applied to each layered tissue structure.

[0006] However, changing the sound speed based on layers may not necessarily satisfy the needs of the examiner. For example, lesions such as tumors and blood vessels may have sound speed values ​​different from those of surrounding tissues, but lesions such as tumors and blood vessels do not necessarily have layered structures in ultrasound images. For this reason, even if the examiner manually changes the sound speed for each of multiple layers, if there are multiple structures that the examiner wants to observe, it may not be possible to display all of them with desirable image quality.

[0007] Japanese Patent Laid-Open Publication No. 6-304172 provides a user interface that allows an examiner to manually change the sound speed in each of a plurality of ultrasonic transducers. Even in this case, for example, when the examiner has a plurality of structures to observe along the same ultrasonic transducer, it may not be possible to display all of them with a preferable image quality. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 8-308832 [Patent Document 2] Japanese Patent Application Publication No. 6-304172 [Patent Document 3] Japanese Patent Application Publication No. 2-274235 Summary of the Invention [Problem to be solved by the invention]

[0009] Therefore, there is a need for an ultrasonic diagnostic apparatus that allows an examiner to easily change the sound speed in a local area as desired in an intuitive and easy-to-understand manner. [Means for solving the problem]

[0010] An ultrasonic diagnostic apparatus according to a first aspect is an ultrasonic diagnostic apparatus that generates an ultrasonic image based on an echo signal from a subject, and includes an ultrasonic probe that receives the echo signal, an interface that allows an operator to specify position information of a local region of the ultrasonic image, and a signal processing means that, when reconstructing the echo signal to reconstruct an ultrasonic image, changes the sound velocity value of the local region based on the position information so as to be different from the sound velocity value of a region other than the local region. Here, the local region is local in both the azimuth direction and the depth direction.

[0011] In the ultrasonic diagnostic apparatus of the second aspect, the change in the sound velocity value is performed according to manual specification by an operator, and the manual specification is performed according to at least one of the following: the operator slides a slide bar displayed on a display device of the ultrasonic diagnostic apparatus; and the operator inputs a numerical value into a dialog box displayed on the display device of the ultrasonic diagnostic apparatus.

[0012] The ultrasonic diagnostic apparatus of the third aspect further includes a designation history storage unit that stores a past position designation history of the position information of the local region and a past manual sound speed designation history of the sound speed information of the local region in association with each other. Also, the signal processing means is configured to execute one or more of the following: for one or more local regions included in the past position designation history, return the setting of the sound speed information to a previous state, for one or more local regions included in the past position designation history, save the setting of the sound speed information for one or more local regions included in the past position designation history, and load the previously set sound speed information for one or more local regions included in the past position designation history.

[0013] In the ultrasonic diagnostic apparatus of the fourth aspect, the change in the sound velocity value is performed by analyzing the echo signal and / or the ultrasonic image corresponding to the local region.

[0014] In the ultrasonic diagnostic apparatus of the fifth aspect, the signal processing means calculates a sound velocity value of a local region based on a phase difference between elements of a signal received by each element of the ultrasonic probe corresponding to the local region.

[0015] The ultrasound diagnostic device of the sixth aspect further comprises an image generator that displays a plurality of image items that are candidates for a local region on an ultrasound image by superimposing them on the ultrasound image. The plurality of image items are arranged in the azimuth direction and the depth direction, and in response to one or more of the plurality of image items being selected, position information of the local region is designated.

[0016] In the ultrasonic diagnostic apparatus of the seventh aspect, the size and / or number of the plurality of image items can be changed automatically or manually.

[0017] In an ultrasound diagnostic device of an eighth aspect, in response to one or more of a plurality of image items being selected, the manner in which the selected one or more of the plurality of image items are displayed is changed so that they are distinguishable from the other one or more of the plurality of image items that were not selected.

[0018] In the ultrasound diagnostic device of the ninth aspect, the signal processing means is configured to generate an ultrasound image of the local region by reconstructing the echo signal using a delay amount or a sound speed parameter corresponding to the sound speed value of the local region, and to generate an ultrasound image of the region other than the local region by reconstructing the echo signal using a delay amount or a sound speed parameter corresponding to the sound speed value of the region other than the local region.

[0019] In a tenth aspect, a program for generating an ultrasonic image based on an echo signal from a subject is provided. The program causes a processor to execute the steps of receiving the echo signal, receiving position information of a local region of the ultrasonic image based on a designation by an operator, and, when reconstructing the echo signal to reconstruct an ultrasonic image, changing the sound velocity value of the local region based on the position information so as to be different from the sound velocity value of a region other than the local region. Here, the local region is local in both the azimuth direction and the depth direction. In an eleventh aspect, a non-transitory storage medium storing the program provided in the tenth aspect is provided. Effect of the Invention

[0020] The present invention has been made in view of the above circumstances, and makes it possible for an examiner to change the sound speed in a desired local area in a simple, intuitive and easy-to-understand manner. [Brief description of the drawings]

[0021] [Figure 1] 1 is a block diagram showing the configuration of an ultrasound diagnostic apparatus 100 according to an embodiment. [Diagram 2] 1 is a conceptual diagram showing a focal position inside a subject when linear scanning is performed in an azimuth direction according to an embodiment; [Diagram 3] 13 is a diagram showing a user interface that allows an operator to specify position information and a sound speed value of a local region of an ultrasound image according to the embodiment. FIG. [Figure 4] 13 is a conceptual diagram illustrating a case in which a plurality of position identification icons arranged in the depth direction and the azimuth direction according to the embodiment are used. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Various embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an ultrasonic diagnostic device 100 according to a specific embodiment of the present invention. The ultrasonic diagnostic device 100 includes an ultrasonic probe 110, a memory 140, and a CPU 120. The CPU 120 can function as a signal processing device. The ultrasonic diagnostic device 100 includes a transmission control unit 112, a reception control unit 113, a transmission delay amount (pattern) storage unit 114, and a reception delay amount (pattern) storage unit 115. The ultrasonic diagnostic device 100 also includes an input unit 131 and a display unit 133. The input unit 131 can receive input from an operator, and receives, for example, input of information such as an instruction, a position, or a numerical value from an operator via a graphical user interface. The input unit 131 includes a keyboard, hard keys, soft keys, and the like. The input unit 131 may include various input devices such as a pointing device such as a mouse, a touch panel, a pen tablet, a touch pad, a track ball, or a joystick, eye tracking, or voice input, etc. The display unit 133 may include a display device such as an LCD (Liquid Crystal Display), a glasses-type or goggle-type head mount display, or a projector.

[0023] The ultrasonic probe 110 includes a plurality of elements (vibrators) 111 constituting a one-dimensional or two-dimensional transducer array. The plurality of elements 111 transmit ultrasonic waves into a living body based on a drive signal applied from a transmission control unit 112, and also receive ultrasonic echoes (echo signals) reflected in the living body and output the received signals to a reception control unit 113. For easier understanding by the reader, nine elements 111 are simply shown in the azimuth direction (X direction in FIG. 1) in the figure, but in reality, 16 to 4000, preferably 100 to 2500, and more preferably about 2000 elements 111 can be arranged in one ultrasonic probe 110. Also, in the Z direction perpendicular to the azimuth direction (X direction in FIG. 1) and the depth direction (Y direction in FIG. 1), 1 to 1000, preferably 8 to 800, and more preferably about 500 elements 111 can be arranged in one ultrasonic probe 110. That is, preferably, 500×2000 elements 111 can be arranged in one ultrasonic probe 110.

[0024] Each element 111 is a transducer using a piezoelectric material (piezoelectric body) such as a piezoelectric ceramic or a polymer piezoelectric element. Each element 111 generates pulsed or continuous wave ultrasound, and forms an ultrasound beam by combining these ultrasound waves. In addition, the multiple elements 111 expand and contract when they receive ultrasound echoes reflected from within the subject BD, generating electrical signals. These electrical signals are output to the reception control unit 113 as ultrasound echo reception signals.

[0025] Each element 111 is in contact with the surface of the subject BD. In the embodiment of FIG. 1, the subject BD includes subcutaneous fat B1, muscle B2, and liver B3. However, it is not essential that the examination site includes the liver B3 of the subject BD. The subject to be examined may be any structure of the examination site of the subject BD that is to be examined by an ultrasound diagnostic device. Furthermore, the subject BD is not limited to the human body, and may be any organism other than a human, such as livestock, pets, or laboratory animals.

[0026] The transmission delay amount (pattern) storage unit 114 stores a plurality of transmission delay amounts used when forming an ultrasonic beam. The transmission control unit 112 selects one pattern from the plurality of delay amounts stored in the transmission delay amount storage unit 114 according to the transmission direction set in the scan control unit 11, and sets the delay time to be given to each of the drive signals of the plurality of elements 111 based on the selected delay amount. This allows the ultrasonic beams transmitted at once from the plurality of elements 111 to reach the entire imaging area of ​​the subject.

[0027] The reception delay (pattern) storage unit 115 stores a plurality of reception delays used when performing focusing on a plurality of reception signals output from a plurality of elements 111. The reception control unit 113 selects one delay from the plurality of reception delays stored in the reception delay storage unit 115, and adds a delay to the plurality of reception signals based on the reception delay and the sound speed in the subject. This performs reception focusing. This focusing generates an echo signal in which the focus of the ultrasonic echo is narrowed. Furthermore, the reception control unit 113 performs envelope detection processing on the formed echo signal. The echo signal is stored in an echo signal memory 142 in the memory 140.

[0028] Here, the delay amount of the received signal is determined based on the sound velocity in the subject BD. In general, the average sound velocity value in the human body is set to 1530 to 1540 m / s. However, in reality, the sound velocity value differs depending on the tissue in the subject BD. In general, the sound velocity value is set to about 1450 m / s in the subcutaneous fat B1, and about 1550 m / s in the muscle B2 or liver B3. However, these values ​​are general and may vary depending on the subject. For example, the sound velocity value is faster in a liver with cirrhosis, and the sound velocity value is slower in a liver with fatty liver. In this embodiment, the reception delay amount storage unit 115 stores delay amounts from, for example, 1000 m / s to 3000 m / s, more preferably from 1430 m / s to 1580 m / s.

[0029] The CPU 120 includes an image generating unit 121, an optimal sound velocity value setting unit 123, and a sound velocity value calculation unit 129. The image generating unit 121 generates a B-mode image, which is tomographic image information related to tissues in the subject, based on the echo signal output from the reception control unit 113. The B-mode image is stored in a B-mode image memory 144 in the memory 140. In other embodiments, the B-mode image is stored in a storage device at a remote location connected via a network. In the example of FIG. 1, the B-mode image 144 is taken as an example, but the present invention is also applicable to the reconstruction of images in other modes.

[0030] The optimal sound velocity value setting unit 123 automatically sets the optimal sound velocity value for image display of a specific part based on the delay amount of the received signal and the echo signal 142 or the B-mode image generated by the image generating unit 121, or based on the delay amount of the received signal and sound velocity designation information from the input unit 131.

[0031] In a specific embodiment of the present invention, the sound speed calculation unit 129 identifies the phase of the echo signal 142 and identifies the difference in sound speed for each sound ray. In another embodiment, the sound speed calculation unit 129 analyzes the B-mode image 144 and identifies the type and size of the tissue contained in the B-mode image 144 to estimate the sound speed value for each sound ray.

[0032] In this embodiment, software (program) is executed by a processor including a CPU 120 to configure a signal processing unit including an image generating unit 121, an optimal sound velocity value setting unit 123, and a sound velocity value calculating unit 129. The software is stored in a memory 140. The software may be recorded on a built-in hard disk, a flash memory, a DVD-ROM, or other recording medium. It is also possible to embody some or most of the functional blocks shown in FIG. 1 using a smartphone, or to embody them using multiple computers connected via a network and located at remote locations.

[0033] 2 shows focal positions inside the subject BD when linear scanning is performed in the azimuth direction X. In this embodiment, similar to conventional linear electronic scanning, aperture positions 211, 221 to 2n1 for transmitting and receiving waves of the element array 111 are moved in sequence, and focal positions 213, 223 to 2n3, 215, 225 to 2n5 for transmitting and receiving waves are moved in sequence to obtain a tomographic image. A desired number of focal points can be set at desired positions (depth direction positions and azimuth direction positions) by controlling the aperture positions and the delay amount at each aperture according to the conventional linear electronic scanning method.

[0034] FIG. 3 shows an example of a user interface in which an operator can specify position information and sound velocity values ​​of a local region of an ultrasound image in a preferred embodiment of the present invention. As shown in the figure, a B-mode image 301 of a subject BD currently being examined is displayed on the display unit 133. When an operator selects an icon (not shown) on the screen labeled "Sound Velocity Local Setting," depth direction boundaries 311, 313, 315 and azimuth direction boundaries 321, 323, 325, 327 are displayed superimposed on the B-mode image 301. In the example of FIG. 3, the depth direction boundaries 311, 313, 315 extend radially according to the scanning cross section of the B-mode image spreading in a fan shape. In another embodiment, the depth direction boundaries 311, 313, 315 extend in a direction perpendicular to the azimuth direction boundaries 321, 323, 325, 327. 3, the azimuth direction boundaries 321, 323, 325, and 327 extend in straight lines perpendicular to the depth direction boundary 313 located in the center. In other embodiments, the azimuth direction boundaries 321, 323, 325, and 327 extend in curved lines constituting parts of concentric circles according to the scanning cross section of the B-mode image spreading in a fan shape.

[0035] The number, positions, and shapes of the depth direction boundaries 311, 313, 315 and the azimuth direction boundaries 321, 323, 325 can be changed in various ways as necessary. In a preferred embodiment of the present invention, the number, positions, and shapes of the depth direction boundaries 311, 313, 315 and the azimuth direction boundaries 321, 323, 325 can be set on the screen by an operator. For example, the numbers of the depth direction boundaries 311, 313, 315 and the azimuth direction boundaries 321, 323, 325 can each be any natural number within the range of 1 to 100. Preferably, the numbers of the depth direction boundaries 311, 313, 315 and the azimuth direction boundaries 321, 323, 325 can each be any natural number within the range of 3 to 20.

[0036] In addition, the depth direction boundaries 311, 313, 315 and the azimuth direction boundaries 321, 323, 325 do not need to be uniform over the entire B mode image 301, and may be dense in a certain portion and sparse in other portions. For example, the Japanese Society of Digestive Cancer Screening has determined 25 types of recommended recording sections (ultrasonic B mode images), and the position and direction in which the operator places the ultrasonic probe 110 on the subject BD are determined for each section. In such a case, for example, the bile duct may be noted in the 14th section out of the 25 sections, while the approximate position in the B mode image 301 where the bile duct exists is known. In a position where the bile duct is likely to exist, one or both of the depth direction boundaries 311, 313, 315 and the azimuth direction boundaries 321, 323, 325 may be dense, and may be sparse in other portions. In another embodiment, organs included in the B-mode image are automatically detected, and the depth direction boundaries 311, 313, 315 and the azimuth direction boundaries 321, 323, 325 are positioned according to the detection results.

[0037] In the embodiment of FIG. 3, the depth direction boundary lines 311, 313, 315 and the azimuth direction boundary lines 321, 323, 325, 327 are used to define the region in which the sound speed value is changed, but various known methods can be used to specify the region in the B mode image. FIG. 4 shows an embodiment in which a plurality of position identification icons 401 arranged in the depth direction Y and the azimuth direction X are used instead of the depth direction boundary lines 311, 313, 315 and the azimuth direction boundary lines 321, 323, 325, 327. The plurality of position identification icons 401 may be fixed (the position, shape, and number cannot be changed). In another embodiment, the position, shape, and number of the plurality of position identification icons 401 can be changed according to the operator's designation. In still another embodiment, the position, shape, and number of the plurality of position identification icons 401 are automatically changed according to the type of the B mode image. For example, the abdominal aorta may be of interest in the fourth cross section among the 25 types of recording cross sections recommended by the Japanese Society of Digestive Cancer Screening, while the approximate position in the B-mode image 301 where the abdominal aorta is present is known. In a position where the abdominal aorta is likely to be present, multiple position identification icons 401 are displayed so that a position identification icon 401 with a shape covering the abdominal aorta is placed. In another embodiment, organs included in the B-mode image are automatically detected, and multiple position identification icons 401 are placed according to the detection result.

[0038] The positions, shapes, and number of the multiple position identification icons 401 can be changed using various methods. For example, if an arbitrary position identification icon 401 is selected for a predetermined time, a list for selecting individual shapes of the position identification icons 401, such as a circle, a rectangle, a sector, an ellipse, etc., is displayed so that the operator can select them. In addition, by pinching in on two position identification icons 401 that are separated in the azimuth direction, the number of position identification icons 401 in the azimuth direction can be increased, and by pinching out on two position identification icons 401 that are separated in the azimuth direction, the number of position identification icons 401 in the azimuth direction can be decreased. By pinching in on two position identification icons 401 that are separated in the depth direction, the number of position identification icons 401 in the depth direction can be increased, and by pinching out on two position identification icons 401 that are separated in the depth direction, the number of position identification icons 401 in the depth direction can be decreased. By pinching in on two position identification icons 401 that are separated in both the azimuth direction and the depth direction, the number of position identification icons 401 in the azimuth direction and the depth direction can be increased simultaneously, and by pinching out on two position identification icons 401 that are separated in both the azimuth direction and the depth direction, the number of position identification icons 401 in the azimuth direction and the depth direction can be decreased simultaneously. Furthermore, by pinching in on individual position identification icons 401, the position identification icons 401 can be made smaller, and by pinching out on individual position identification icons 401, the position identification icons 401 can be made larger.

[0039] In FIG. 3, when a region for which a change in sound velocity value is desired is selected, a selection display icon 331 is displayed above the selected region. The selection of the region is performed by the input unit 131. The selection by the input unit 131 includes selection by a pointing device such as a mouse, a touch panel, a pen tablet, a touch pad, a trackball, or a joystick, or by keyboard input. When the input by the input unit 131 is keyboard input, the region is selected by moving the selected region in order using a tab key or by keying in a number assigned to each region. In addition, the region can be selected by various input devices such as eye tracking or voice input instead of or in combination with a pointing device or keyboard input. In this embodiment, the selection display icon 331 shows the range (boundary) of the selected region to the operator by spreading multiple concentric circles at a predetermined speed only within the selected region, like ripples spreading on the surface of the water when a pebble is thrown into a pond. In another embodiment, the display of the selected region is changed using a predetermined color, shading, contrast change, blinking, etc., and the range (boundary) of the selected region is shown to the operator. In yet another embodiment, the periphery of the selected area is changed using a predetermined color, shading, blinking, or the like, and the range (boundary) of the selected area is clearly indicated to the operator. In yet another embodiment, the display of the selected area is not changed, and the display of the area other than the selected area is changed using a predetermined color, shading, contrast change, blinking, or the like, and the range (boundary) of the selected area is clearly indicated to the operator. That is, in response to the selection of one or more of the multiple image items, the display manner of the selected one or more multiple image items is changed so that they can be distinguished from the other one or more multiple image items that were not selected. The portion surrounded by the depth direction boundary lines 311, 313, 315 and the azimuth direction boundary lines 321, 323, 325, 327 corresponds to the "image item" referred to here. The selected area is local or limited in both the azimuth direction and the depth direction. The size and / or number of the multiple image items can be changed automatically or manually.

[0040] In FIG. 4, when a position identification icon 401 corresponding to a region in which a change in sound speed value is desired is selected, the selected position identification icon 401 changes to a selection display icon 403. The selection display icon 403 is distinguishable from the position identification icon 401 in terms of color, shape, pattern, blinking, etc. That is, in response to the selection of one or more of the multiple image items, the display mode of the selected one or more multiple image items is changed so that they can be distinguished from the other one or more multiple image items that were not selected. The position identification icon 401 corresponds to the "image item" referred to here. The position identification icon 401 is local or limited in both the azimuth direction and the depth direction. The image generating unit 121 displays a plurality of image items that are candidates for a local region by superimposing them on the B-mode image 144. The multiple image items are arranged in the azimuth direction and the depth direction, and in response to the selection of one or more of the multiple image items, the position information of the local region is specified.

[0041] The selection of the position identification icon 401 is performed by the input unit 131. The selection by the input unit 131 includes selection by a pointing device such as a mouse, a touch panel, a pen tablet, a touch pad, a trackball, or a joystick, or by keyboard input. When the input by the input unit 131 is keyboard input, the region is selected by sequentially moving the selected position identification icon 401 using a tab key or by keying in the number assigned to each position identification icon 401. In addition, instead of or in combination with a pointing device or keyboard input, the position identification icon 401 can be selected by various input devices such as eye tracking or voice input. In one embodiment, the selected region is only the region within the selection display icon 403. In another embodiment, the selected region includes not only the region within the selection display icon 403 but also the region outside it.

[0042] In FIG. 3, when a region in which a change in sound velocity value is desired is selected, a slider icon 341 is displayed on the display unit 133 together with the B-mode image 301. The slider icon 341 has a slide handle 343. When the operator moves the slide handle 343 to the right, the sound velocity becomes faster, and when the operator moves the slide handle 343 to the left, the sound velocity becomes slower. In a preferred embodiment of the present invention, the sound velocity can be adjusted according to a predetermined linear function between 1000 m / s and 2000 m / s with 1500 m / s as the center. In another embodiment of the present invention, the sound velocity can be adjusted according to a predetermined nonlinear function between 1200 m / s and 3000 m / s with 1530 m / s as the center. In this example, a function including a curve in which the change in sound velocity with respect to the moving distance from the center is proportional to the moving distance near the center, but for example, the change in sound velocity with respect to the moving distance is very large at a position close to the right end is selected. In a particular embodiment of the invention, in response to the operator moving the slide handle 343 to the right, the signal processing unit 120 generates a high-pitched sound from a speaker (not shown) corresponding to a faster speed of sound, and in response to the operator moving the slide handle 343 to the left, the signal processing unit 120 generates a low-pitched sound from the speaker corresponding to a slower speed of sound.

[0043] In a specific embodiment of the present invention, in addition to or instead of the slider icon 341, a spin box 351 and a dialog box such as a dial icon assigned to each of the thousands to units digits are also displayed on the display unit 133. The value displayed in the spin box 351 is linked to the position of the slide handle 343 in the slider icon 341, and when the slide handle 343 is moved, the sound speed value corresponding to the moved position is displayed in the spin box 351. The value in the spin box 351 can be changed by operating the up-down buttons (up and down buttons) 353, 355 on the right end of the spin box 351, and the position of the slide handle 343 of the slider icon 341 automatically moves accordingly. The value in the spin box 351 can also be changed by inputting a value through the input unit 131 (for example, keyboard input or voice input).

[0044] In a specific embodiment of the present invention, a load button 361, an UNDO button 363, and a save button 365 are displayed on the display unit 133. As described with reference to FIG. 3, when a region in which a sound velocity value is desired to be changed is selected, a selection display icon 331 is displayed above the selected region. When the load button 361 is selected in this state, information stored in the designation history storage unit 146 is selectively referred to. The designation history storage unit 146 stores sound velocity values ​​previously set in each region. Specifically, sound velocity values ​​of 1 to 100 previously set for each region are stored. More preferably, sound velocity values ​​of 2 to 10 previously set for each region are stored. In a specific embodiment of the present invention, the upper limit number of sound velocity values ​​that can be stored for each region is different. In a specific embodiment of the present invention, when the load button 361 is pressed once, the sound velocity value most recently set is called up and displayed in the spin box 351, and the slider icon 341 is also linked to this value. When the load button 361 is pressed, for example, three times, the sound velocity value set three times previously is called up and displayed in the spin box 351, and the slider icon 341 is also linked to this value. In a specific embodiment of the present invention, when the load button 361 is pressed one or more times, the sound velocity values ​​set in the past are called up and displayed as a list. When the operator selects a desired value from this list, the selected value is displayed in the spin box 351, and the slider icon 341 is also linked to this value. The sound velocity values ​​displayed as the list can be modified or deleted. In a specific embodiment of the present invention, when the load button 361 is selected while a region in which the sound velocity value is desired to be changed is not selected, a display and / or a sound is provided to prompt the operator to select a region in which the sound velocity value is desired to be changed.

[0045] In a specific embodiment of the present invention, when a region in which a sound velocity value change is desired is selected and a sound velocity value to be applied to the selected region is set, the position information of the local region of the ultrasound image and the sound velocity value set corresponding thereto are sent to the image generating unit 121 after the save button 365 is selected. The region in which a sound velocity value change is desired does not have to be a single region, and any continuous multiple regions or multiple regions separated from each other can be selected and a sound velocity value common to these multiple regions can be set. The image generating unit 121 that receives the position information of the local region of the ultrasound image and the sound velocity value set corresponding thereto reconstructs an image according to the position information of the local region of the ultrasound image and the sound velocity value set corresponding thereto. More specifically, the image generating unit 121 identifies all focus points corresponding to the position information of the local region of the ultrasound image, and uses the sound velocity value set for the receive beamforming at all identified focus points. When performing a delay-and-sum process in which echo signals received at each of the ultrasound transducers are delayed and summed, a delay corresponding to the set sound velocity value is applied. In a specific embodiment of the present invention, the delay amount pattern stored in the reception delay amount storage unit 115 is updated to the position information of the local area of ​​the ultrasound image received by the image generation unit 121 and the sound speed value set corresponding thereto. In a specific embodiment of the present invention, the delay amount pattern stored in the transmission delay amount storage unit 114 is updated to the position information of the local area of ​​the ultrasound image received by the image generation unit 121 and the sound speed value set corresponding thereto. In a specific embodiment of the present invention, the sound speed value previously set in each area stored in the designation history storage unit 146 is updated according to the position information of the local area of ​​the ultrasound image received by the image generation unit 121 and the sound speed value set corresponding thereto. The delay amount of the local area designated by the operator is changed according to the designated sound speed value as described above, but the sound speed value of the area other than the local area remains unchanged. This allows the sound speed value of the local area to be changed to be different from the sound speed value of the area other than the local area. This local area is local in both the azimuth direction and the depth direction.

[0046] In a specific embodiment of the present invention, a B-mode image 144 covering all regions is generated for each of the sound velocity values ​​of the local region and the sound velocity values ​​of the region other than the local region, and these are cut and pasted together to be combined. Such cutting and pasting may be performed for two B-mode images 144, but when multiple combinations of local regions and their sound velocity values ​​are set, cutting and pasting is performed for three or more B-mode images 144. The B-mode image 144 to be cut and pasted does not need to be a B-mode image 144 covering all regions, and may be local in the azimuth direction, the depth direction, or both, as long as the required region is covered.

[0047] In a specific embodiment of the present invention, the sound velocity value once defined by selecting the save button 365 can be canceled by pressing the UNDO button 363. The most recent sound velocity value (the sound velocity value immediately before the save button 365 is selected) stored in the designation history storage unit 146 and the position information of the local region are sent to the image generation unit 121. The image generation unit 121, which has received the position information of the local region of the ultrasound image and the sound velocity value set corresponding thereto, reconstructs the image according to the position information of the local region of the ultrasound image and the sound velocity value set corresponding thereto. More specifically, the image generation unit 121 identifies all focus points corresponding to the position information of the local region of the ultrasound image, and uses the sound velocity value set for the receive beamforming at all identified focus points. When performing a delay-and-sum process in which echo signals received at each of the ultrasound transducers are delayed and added, a delay corresponding to the set sound velocity value is applied. In a specific embodiment of the present invention, the pattern of the delay amount stored in the receive delay amount storage unit 115 is updated to the position information of the local region of the ultrasound image received by the image generation unit 121 and the sound velocity value set corresponding thereto. In a specific embodiment of the present invention, the delay pattern stored in the transmission delay storage unit 114 is updated to the position information of the local area of ​​the ultrasound image received by the image generation unit 121 and the sound speed value set corresponding thereto. In a specific embodiment of the present invention, the sound speed value previously set in each area stored in the designation history storage unit 146 is updated so that the sound speed value when the save button 365 was pressed in the local area by the image generation unit 121 is deleted. In a specific embodiment of the present invention, by pressing the UNDO button 363 multiple times, the sound speed information setting can be returned not only to the previous state but also to the state two or more previous states.

[0048] Returning to Fig. 2, the human body as a subject usually has tissues with different sound speeds, such as skin, fat, muscle, and organ parenchyma, arranged in layers as shown in regions B1, B2, and B3 in Fig. 2, from the body surface side close to the element array 111 of the probe. The delay time correction values ​​are significantly different between the shallow focal position 213 and the deep focal position 215 at the aperture position 211, but the distribution of delay time correction values ​​corresponding to focal points 223 and 225 with the same focal length at the adjacent aperture position 221 is generally very close to the correction values ​​corresponding to the focal lengths 213 and 215. Based on this characteristic, the distribution of optimal delay time correction values ​​obtained for each focal length at the initial aperture position 211 can be used as the initial value for the procedure of optimizing the delay time correction value at the adjacent aperture position 221.

[0049] However, even if the echo signals are from foci with the same focal distance at the aperture position close to each other, the sound speed value of the ultrasonic waves in the biological tissue through which they propagate may be different. If the sound speed value set for determining the delay time differs from the actual sound speed value, the reception focus will deteriorate, the spatial resolution will deteriorate, and a preferable contrast will not be obtained.

[0050] When there is a difference in the sound velocity value of the ultrasonic wave propagated in the biological tissue between two echo signals from foci with the same focal distance at the aperture position close to each other, the phases of the two echo signals will be different. By automatically changing the sound velocity value (delay time correction value) according to the degree of the phase difference of the echo signals, the spatial resolution can be improved and a preferable contrast can be obtained. In one embodiment of the present invention, the phases of n echo signals from foci with the same focal distance are analyzed, and the sound velocity value (delay time correction value) of the echo signal that deviates from the average value by a predetermined standard deviation is changed. In this case, preferably, n can be a predetermined natural number within the range of 3 to 1000. More preferably, n can be a predetermined natural number within the range of 10 to 500. In another embodiment of the present invention, the value of n can be manually changed by the operator. Also, an echo signal with a degree of phase difference outside a predetermined deviation value range of ±0.1σ to ±4σ can be the target for automatic sound velocity value change. Preferably, an echo signal with a degree of phase difference outside a predetermined deviation value range of ±0.5σ to ±2σ can be the target for automatic sound velocity value change. More preferably, echo signals whose phase difference is outside the range of ±1σ can be subject to automatic change in sound velocity value. In another embodiment of the present invention, the value of the predetermined deviation value can be manually changed by an operator.

[0051] In another embodiment of the present invention, the invention described in Japanese Patent No. 6081744 is used to set the sound velocity value for each focus. The echo signal is reconstructed to generate a B-mode image, the thickness of the subcutaneous fat (and the thickness of the muscle, if necessary) contained in the B-mode image is measured, and the optimal sound velocity value for each focus is set according to the measured fat thickness (and the thickness of the muscle, if necessary). In another embodiment of the present invention, the phase difference of the echo signal is determined taking into consideration the difference in the measured fat thickness (and the thickness of the muscle, if necessary). The sound velocity value (delay time correction value) is automatically changed according to this determined phase difference of the echo signal.

[0052] In this embodiment, software (program) is executed by a processor including a CPU 120 to configure an image generating unit 121, an optimum sound velocity value setting unit 123, and a sound velocity value calculating unit 129. The software is stored in a memory 140. The software may be recorded on a built-in hard disk, a flash memory, a DVD-ROM, or other recording medium.

[0053] Although the present invention has been described above with a focus on the most preferred embodiment, it will be apparent to those skilled in the art that the present invention can be implemented by making various changes and modifications to the embodiment within the technical scope of the present invention. [Explanation of symbols]

[0054] 100 Ultrasound diagnostic equipment 110 Ultrasonic probe 111 Transducer 112 Communication control section 113 Reception control section 114 Transmission delay amount (pattern) storage unit 115 Reception delay amount (pattern) storage unit 120 CPU / signal processing means / signal processing section 121 Image Generation Unit 123 Optimum sound velocity value setting section 129 Sound Speed ​​Calculation Section 131 Input section 133 Display section 140 Memory 142 Echo Signal 144, 301 B-mode images 146 Designation history memory unit 211, 221~2n1 caliber position 213, 223~2n3, 215, 225~2n5 Focal position 311, 313, 315 Depth direction boundary 321, 323, 325, 327 Azimuth direction boundaries 331, 403 selection display icon 341 Slider Icon 343 Slide Handle 351 Spinbox 353 Up button 355 Down button 361 Load button 363 UNDO button 365 Save Button 401 Location Icon

Claims

1. An ultrasound diagnostic device that generates an ultrasound image based on an echo signal from a subject, an ultrasonic probe for receiving the echo signal; an interface that allows an operator to specify position information of a local region of an ultrasound image; a signal processing means for changing a sound velocity value in the local region based on the position information so as to be different from a sound velocity value in a region other than the local region when reconstructing the echo signal to reconstruct an ultrasonic image; Equipped with An ultrasonic diagnostic apparatus, wherein the local region is local in both the azimuth direction and the depth direction.

2. The change in the sound velocity value is performed according to a manual instruction by an operator, The manual designation is: a slide operation by an operator of a slide bar displayed on a display device of the ultrasonic diagnostic apparatus; inputting a numerical value into a dialogue box displayed on a display device of the ultrasound diagnostic apparatus by an operator; The ultrasonic diagnostic apparatus according to claim 1 , wherein the ultrasonic diagnostic apparatus is configured to perform one or more of the following steps.

3. A past position designation history of the position information of the local area; A history of manual sound speed designation of the sound speed information of the local region; and The apparatus further includes a designation history storage unit that stores the designation history in association with each other, The signal processing means For one or more local regions included in the past position specification history, returning the setting of the sound speed information to one or more previous states; saving settings of sound speed information for one or more local regions included in the past position designation history; Loading previously set sound speed information for one or more local regions included in the past position designation history; The ultrasound diagnostic device of claim 2 , configured to perform one or more of the following:

4. The ultrasonic diagnostic apparatus according to claim 1 , wherein the change in the sound velocity value is performed by analyzing an echo signal and / or an ultrasonic image corresponding to the local region.

5. The signal processing means The ultrasonic diagnostic apparatus according to claim 4 , wherein the sound velocity value of the local region is calculated based on a phase difference between elements of a reception signal of each element of an ultrasonic probe corresponding to the local region.

6. An image generating unit that displays a plurality of image items that are candidates for the local region on the ultrasound image by superimposing the image items, the plurality of image items are arranged in the azimuth direction and the depth direction; The ultrasound diagnostic apparatus according to claim 1 , wherein the position information of the local region is specified in response to one or more of the plurality of image items being selected.

7. The ultrasonic diagnostic apparatus according to claim 6 , wherein the size and / or number of the plurality of image items is changeable automatically or manually.

8. The ultrasound diagnostic apparatus of claim 6, wherein in response to one or more of the plurality of image items being selected, a display manner is changed so that the selected one or more of the plurality of image items are distinguishable from the other one or more of the plurality of image items that were not selected.

9. The signal processing means generating an ultrasound image of the local area by reconstructing the echo signals using delays or sound speed parameters corresponding to the sound speed values ​​of the local area; 8. The ultrasonic diagnostic device according to claim 1, configured to generate an ultrasonic image of a region other than the local region by reconstructing the echo signal using a delay amount or a sound speed parameter corresponding to a sound speed value of the region other than the local region.

10. A program for generating an ultrasound image based on an echo signal from a subject, receiving the echo signal; receiving position information of a local region of an ultrasound image based on a designation by an operator; When reconstructing the echo signals to reconstruct an ultrasound image, a sound velocity value in the local region is changed based on the position information so as to be different from a sound velocity value in a region other than the local region; to a processor, The localized region is localized in both the azimuth direction and the depth direction.

11. A non-transitory storage medium storing the program according to claim 10.

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