Ultrasound diagnostic device capable of changing the sound velocity value in a local area

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 the 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 the sound velocity-adjusted ultrasound image. [Background technology]

[0002] An ultrasound diagnostic device transmits ultrasound waves from an ultrasound probe equipped with multiple ultrasound transducers toward the biological tissue of a subject. Echo signals of the ultrasound waves 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 by each of the ultrasonic transducers are input to a receive beamformer, which performs receive beamforming on the echo signals received by each of the ultrasonic transducers. This receive beamforming includes a delay-and-sum process that delays and sums the echo signals received by each of the ultrasonic transducers.

[0004] The delay time in receive beamforming is set assuming that the speed of sound of ultrasound in biological tissue is a predetermined value (e.g., 1530 m / s). However, the speed of sound of ultrasound in biological tissue may differ for each subject or each part of the body. For example, the speed of sound in muscle may be 1590 m / s, and the speed of sound in bone may be 3000 m / s. If the speed of sound set when determining the delay time differs from the actual speed of sound, the receive focus may deteriorate. If the speed of sound set when determining the delay time differs from the actual speed of sound, the spatial resolution may deteriorate, and desirable contrast may not be obtained.

[0005] In relation to this problem, Japanese Patent Laid-Open Publication No. 8-308832 provides an ultrasonic diagnostic device that displays patterns according to different diagnostic regions of a subject and according to the layered tissue structures of the diagnostic regions, 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 ​​that are different from those of surrounding tissues, but lesions such as tumors and blood vessels do not necessarily appear as 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 No. 6-304172 provides a user interface that allows an examiner to manually change the sound speed for each of multiple ultrasonic transducers. Even in this case, for example, if the examiner wants to observe multiple structures along the same ultrasonic transducer, it may not be possible to display all of them with a desirable 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 demand for an ultrasonic diagnostic apparatus that allows the examiner to easily change the sound speed in a desired local area 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 echo signals from a subject, and includes: an ultrasonic probe that receives the echo signals; an interface that allows an operator to specify position information of a local region of the ultrasonic image; and signal processing means that, when reconstructing the echo signals to reconstruct an ultrasonic image, changes the sound velocity value in the local region based on the position information so that it differs from the sound velocity value in regions 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 device of the second aspect, the change in the sound velocity value is performed in accordance with manual specification by the operator, and the manual specification is performed in accordance with at least one of the following: the operator sliding a slide bar displayed on the display device of the ultrasonic diagnostic device; and the operator inputting a numerical value into a dialog box displayed on the display device of the ultrasonic diagnostic device.

[0012] The ultrasonic diagnostic apparatus of a 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. The signal processing means is configured to perform one or more of the following: restore 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 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 the sound velocity value of the local area based on the phase difference between the elements of the ultrasonic probe corresponding to the local area in the received signals.

[0015] The ultrasound diagnostic apparatus of the sixth aspect further comprises an image generation unit that displays a plurality of image items that are candidates for the local region superimposed on the ultrasound image. The plurality of image items are arranged in the azimuth direction and the depth direction, and in response to the selection of one or more of the plurality of image items, position information of the local region is specified.

[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 the selection of one or more of a plurality of image items, the display manner of the selected one or more of a plurality of image items is changed so that the selected one or more of a plurality of image items can be distinguished from the other one or more of a plurality of image items that were not selected.

[0018] In the ultrasonic diagnostic device of the ninth aspect, the signal processing means is configured to generate an ultrasonic image of the local region by reconstructing echo signals using delay amounts or sound speed parameters corresponding to the sound speed values ​​in the local region, and to generate an ultrasonic image of the region other than the local region by reconstructing echo signals using delay amounts or sound speed parameters corresponding to the sound speed values ​​in the region other than the local region.

[0019] In a tenth aspect, there is provided a program for generating an ultrasound image based on echo signals from a subject. The program causes a processor to execute the following steps: receiving the echo signals; receiving position information of a local region of the ultrasound image based on a specification by an operator; and, when reconstructing the echo signals to reconstruct an ultrasound image, changing the sound velocity value in the local region based on the position information so that it is different from the sound velocity value in regions other than the local region. Here, the local region is local in both the azimuth direction and the depth direction. In addition, in an eleventh aspect, there is provided a non-transitory storage medium storing the program provided in the tenth aspect. [Effects 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 explanation of the drawings]

[0021] [Figure 1] 1 is a block diagram showing the configuration of an ultrasound diagnostic apparatus 100 according to an embodiment. [Figure 2] 10 is a conceptual diagram showing a focal position inside an object when linear scanning is performed in the azimuth direction according to the embodiment; [Figure 3] 10 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 an embodiment. FIG. [Figure 4] FIG. 10 is a conceptual diagram illustrating a case where a plurality of position identification icons arranged in the depth direction and the azimuth direction according to the embodiment are used. DETAILED DESCRIPTION OF THE INVENTION

[0022] Various embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an ultrasound diagnostic apparatus 100 according to a specific embodiment of the present invention. The ultrasound diagnostic apparatus 100 includes an ultrasound probe 110, a memory 140, and a CPU 120. The CPU 120 can function as a signal processing device. The ultrasound diagnostic apparatus 100 also 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 ultrasound diagnostic apparatus 100 also includes an input unit 131 and a display unit 133. The input unit 131 can accept operator input, such as instructions, positions, numerical values, and other information, via a graphical user interface (GUI) from an operator. 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, as well as eye tracking and voice input. The display unit 133 may include a display device such as an LCD (Liquid Crystal Display), a head-mounted display such as a glasses-type or goggle-type display, or a projector.

[0023] The ultrasound probe 110 includes a plurality of elements (vibrators) 111 that form a one-dimensional or two-dimensional transducer array. The plurality of elements 111 transmit ultrasound waves into a living body based on a drive signal applied from a transmission control unit 112, and also receive ultrasound echoes (echo signals) reflected within the living body and output 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 ultrasound probe 110. Furthermore, 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. In other words, preferably 500 × 2000 elements 111 can be arranged in one ultrasonic probe 110.

[0024] Each element 111 is a transducer made of a piezoelectric material (piezoelectric body) such as a piezoelectric ceramic or a polymer piezoelectric element. Each element 111 generates pulsed or continuous wave ultrasound waves, and forms an ultrasound beam by combining these ultrasound waves. In addition, the multiple elements 111 expand and contract when receiving 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 region includes the liver B3 of the subject BD. The subject of examination can be any structure of the examination region of the subject BD that is the subject of examination by an ultrasound diagnostic device. Furthermore, the subject BD is not limited to the human body, and can also be a non-human organism such as livestock, pets, or laboratory animals.

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

[0027] The reception delay (pattern) storage unit 115 stores a plurality of reception delays used when performing focusing processing 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 the plurality of reception signals with delays based on the reception delay and the speed of sound inside the subject. This performs reception focusing processing. This focusing processing 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 speed of sound within the subject BD. Generally, the average speed of sound within the human body is set to 1530 to 1540 m / s. However, in reality, the speed of sound varies depending on the tissue within the subject BD. Generally, the speed of sound in subcutaneous fat B1 is approximately 1450 m / s, and the speed of sound in muscle B2 or liver B3 is approximately 1550 m / s. However, these values ​​are general and may vary depending on the subject. For example, the speed of sound is faster in a liver with cirrhosis and slower in a liver with fatty liver. In this embodiment, the reception delay amount storage unit 115 stores delay amounts ranging from 1000 m / s to 3000 m / s, more preferably from 1430 m / s to 1580 m / s.

[0029] The CPU 120 includes an image generation unit 121, an optimal sound velocity value setting unit 123, and a sound velocity value calculation unit 129. The image generation unit 121 generates a B-mode image, which is tomographic image information relating to tissue within the subject, based on the echo signals 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. Although the example in FIG. 1 is described using the B-mode image 144 as an example, 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 region 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 specification information from the input unit 131.

[0031] In a specific embodiment of the present invention, the sound speed value 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 value calculation unit 129 analyzes the B-mode image 144 and identifies the type and size of the tissue included in the B-mode image 144, thereby estimating 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 memory 140. The software may be recorded on a built-in hard disk or on a recording medium such as a flash memory or a DVD-ROM. Some or most of the functional blocks shown in FIG. 1 may be realized using a smartphone, or may be realized 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 sequentially moved, and focal positions 213, 223 to 2n3, 215, 225 to 2n5 for transmitting and receiving waves are sequentially moved and scanned to obtain a tomographic image. According to the conventional linear electronic scanning method, 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.

[0034] FIG. 3 shows an example of a user interface that allows an operator to 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 the subject BD currently being examined is displayed on the display unit 133. When the operator selects an icon (not shown) labeled "Local Sound Velocity Setting" on the screen, depth-direction boundaries 311, 313, and 315 and azimuth-direction boundaries 321, 323, 325, and 327 are displayed superimposed on the B-mode image 301. In the example of FIG. 3, the depth-direction boundaries 311, 313, and 315 extend radially along the scanning cross section of the B-mode image, which spreads like a fan. In other embodiments, the depth-direction boundaries 311, 313, and 315 extend in a direction perpendicular to the azimuth-direction boundaries 321, 323, 325, and 327. 3, the azimuth direction boundary lines 321, 323, 325, and 327 extend in straight lines perpendicular to the centrally located depth direction boundary line 313. In other embodiments, the azimuth direction boundary lines 321, 323, 325, and 327 extend in curved lines constituting parts of concentric circles in accordance with 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, and 315 and the azimuth-direction boundaries 321, 323, and 325 can be modified as needed. In a preferred embodiment of the present invention, the number, positions, and shapes of the depth-direction boundaries 311, 313, and 315 and the azimuth-direction boundaries 321, 323, and 325 can be set on the screen by an operator. For example, the numbers of the depth-direction boundaries 311, 313, and 315 and the azimuth-direction boundaries 321, 323, and 325 can each be any natural number within the range of 1 to 100. Preferably, the numbers of the depth-direction boundaries 311, 313, and 315 and the azimuth-direction boundaries 321, 323, and 325 can each be any natural number within the range of 3 to 20.

[0036] Furthermore, the depth-direction boundaries 311, 313, and 315 and the azimuth-direction boundaries 321, 323, and 325 do not need to be uniform throughout the B-mode image 301; they may be dense in certain areas and sparse in other areas. For example, the Japanese Society of Digestive Cancer Screening defines 25 types of recommended recording cross sections (ultrasound B-mode images), and for each cross section, the position and direction in which the operator places the ultrasound probe 110 on the subject BD are specified. In such a case, for example, a bile duct may be of interest in the 14th cross section of the 25 cross sections, but the approximate location of the bile duct in the B-mode image 301 is known. At positions where the bile duct is likely to be present, one or both of the depth-direction boundaries 311, 313, and 315 and the azimuth-direction boundaries 321, 323, and 325 may be dense, and sparse in other areas. In another embodiment, organs included in the B-mode image are automatically detected, and depth direction boundaries 311, 313, 315 and azimuth direction boundaries 321, 323, 325 are arranged according to the detection results.

[0037] In the example of FIG. 3, the depth-direction boundaries 311, 313, and 315 and the azimuth-direction boundaries 321, 323, 325, and 327 define the regions in which the sound speed values ​​are changed. However, various known techniques can be used to identify regions within a B-mode image. FIG. 4 shows an example in which, instead of the depth-direction boundaries 311, 313, and 315 and the azimuth-direction boundaries 321, 323, 325, and 327, multiple position identification icons 401 are arranged in the depth direction Y and the azimuth direction X. The multiple position identification icons 401 may be fixed (their positions, shapes, and numbers cannot be changed). In other examples, the positions, shapes, and numbers of the multiple position identification icons 401 can be changed according to operator specifications. In still other embodiments, the positions, shapes, and numbers of the multiple position identification icons 401 are automatically changed depending on the type of B-mode image. For example, the abdominal aorta may be of interest in the fourth cross section out of the 25 types of recording cross sections recommended by the Japanese Society of Digestive Cancer Screening, but the approximate position in the B-mode image 301 where the abdominal aorta is present is known. At positions where the abdominal aorta is likely to be present, multiple location identification icons 401 are displayed so that a location identification icon 401 with a shape that covers the abdominal aorta is placed. In another embodiment, organs included in the B-mode image are automatically detected, and multiple location identification icons 401 are placed according to the detection results.

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

[0039] In FIG. 3 , when a region for which a sound velocity value change is desired is selected, a selection display icon 331 is displayed above the selected region. Region selection is performed using the input unit 131. Selection using the input unit 131 includes selection using a pointing device such as a mouse, touch panel, pen tablet, touchpad, trackball, or joystick, or keyboard input. When input using the input unit 131 is keyboard input, the region is selected by sequentially moving through the selected regions using the tab key or by keying in the number assigned to each region. Region selection can also be performed using 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 displays multiple concentric circles within the selected region at a predetermined speed, similar to ripples spreading on the surface of a pond when a pebble is thrown into it, to clearly indicate the range (boundary) of the selected region to the operator. In other embodiments, the selected region is displayed differently using a predetermined color, shading, contrast change, blinking, or the like to clearly indicate the range (boundary) of the selected region to the operator. In yet another embodiment, the perimeter of the selected area is changed using a predetermined color, shading, blinking, etc., to clearly indicate to the operator the range (boundary) of the selected area. In yet another embodiment, the display of the selected area is not changed, and the area outside the selected area is changed using a predetermined color, shading, contrast change, blinking, etc., to clearly indicate to the operator the range (boundary) of the selected area. 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 area 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 herein. The selected area is localized or limited in both the azimuth and depth directions. 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 for which a sound velocity value change 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. In other words, 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 generation unit 121 displays multiple image items that are candidates for the local region superimposed 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] Selection of the position identification icon 401 is performed by the input unit 131. Selection by the input unit 131 includes selection by a pointing device such as a mouse, touch panel, pen tablet, touchpad, trackball, or joystick, or by keyboard input. When input by the input unit 131 is keyboard input, the region is selected by sequentially moving the selected position identification icon 401 using the tab key or by key-inputting the number assigned to each position identification icon 401. Furthermore, 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 selected display icon 403. In another embodiment, the selected region includes not only the region within the selected display icon 403 but also the region outside it.

[0042] In FIG. 3, when a region in which a sound velocity value change is desired is selected, a slider icon 341 is displayed on the display unit 133 along 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 in accordance with 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 in accordance with a predetermined nonlinear function between 1200 m / s and 3000 m / s, with 1530 m / s as the center. In this example, a function is selected that includes a curve in which the change in sound velocity relative to the distance traveled from the center is proportional to the change in sound velocity near the center, but the change in sound velocity relative to the distance traveled is very large near the right end, for example. In a particular embodiment of the present 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 dialog box such as a spin box 351 and dial icons assigned to each of the thousands to ones digits are also displayed on the display unit 133. The value displayed in the spin box 351 is linked to the position of a slide handle 343 on 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 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 on the slider icon 341 automatically moves accordingly. The value in the spin box 351 can also be changed by entering a value using 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 for which a sound velocity value change is desired 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 referenced in a selectable manner. The designation history storage unit 146 stores sound velocity values ​​previously set for 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 of the number of sound velocity values ​​that can be stored varies for each region. In a specific embodiment of the present invention, when the load button 361 is pressed once, the most recently set sound velocity value 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 recalled 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, previously set sound velocity values ​​are recalled 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 a list can be modified or deleted. In a specific embodiment of the present invention, when the load button 361 is selected when a region for which the sound velocity value is desired to be changed has not been selected, a display and / or audio is provided to prompt the operator to select a region for which the sound velocity value is desired to be changed.

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

[0046] In a specific embodiment of the present invention, B-mode images 144 covering the entire region are generated using the sound velocity values ​​of the local region and the sound velocity values ​​of the region other than the local region, and these are then cut and pasted together. This cutting and pasting may be performed on two B-mode images 144, but if multiple combinations of local regions and their sound velocity values ​​are set, cutting and pasting is performed on three or more B-mode images 144. The B-mode images 144 to be cut and pasted do not need to be B-mode images 144 covering the entire region, 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, a sound velocity value that has been 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 was selected) stored in the designation history storage unit 146 and position information of the local region are sent to the image generation unit 121. The image generation unit 121, having received the position information of the local region of the ultrasound image and the corresponding set sound velocity value, reconstructs an image according to the position information of the local region of the ultrasound image and the corresponding set sound velocity value. 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 receive beamforming at all identified focus points. When performing a delay-and-sum process in which echo signals received at each ultrasound transducer 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 pattern stored in the receive delay 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 corresponding set sound velocity value. In a specific embodiment of the present invention, the delay pattern stored in the transmission delay amount storage unit 114 is updated to the position information of the local region of the ultrasound image received by the image generation unit 121 and the sound speed value set corresponding to the position information. In a specific embodiment of the present invention, the sound speed value previously set in each region 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 region 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 restored not only to the previous state, but also to the state two or more times back.

[0048] Returning to Figure 2, to continue the explanation, a human body as a subject typically 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 Figure 2, from the body surface side closest to element array 111 of the probe. The delay time correction values ​​differ greatly between shallow focal position 213 and deep focal position 215 at aperture position 211, but the distributions of delay time correction values ​​corresponding to focal points 223 and 225 with the same focal length at adjacent aperture position 221 are generally very close to the correction values ​​corresponding to focal lengths 213 and 215, respectively. Based on this characteristic, the distribution of optimal delay time correction values ​​initially found for each focal length at aperture position 211 can be used as an initial value for the procedure of optimizing the delay time correction value at adjacent aperture position 221.

[0049] However, even if echo signals are from foci with the same focal length at adjacent aperture positions, the sound speed of the ultrasound waves in the biological tissue through which they propagate may differ. 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 desirable contrast will not be obtained.

[0050] When there is a difference in the sound velocity of the ultrasound waves propagating through biological tissue between two echo signals from foci with the same focal length at adjacent aperture positions, the phases of the two echo signals will differ. By automatically changing the sound velocity (delay time correction value) according to the degree of this phase difference between the echo signals, spatial resolution can be improved and favorable contrast can be obtained. In one embodiment of the present invention, the phases of n echo signals from foci with the same focal length are analyzed, and the sound velocity (delay time correction value) of echo signals that deviate from the average value by a predetermined standard deviation is changed. In this case, n is preferably a predetermined natural number within the range of 3 to 1,000. More preferably, n is a predetermined natural number within the range of 10 to 500. In other embodiments of the present invention, the value of n can be manually changed by an operator. Furthermore, echo signals whose phase difference is outside a predetermined deviation range of ±0.1σ to ±4σ can be subject to automatic sound velocity value change. Preferably, echo signals whose phase difference is outside a predetermined deviation range of ±0.5σ to ±2σ can be subject to 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 utilized when setting the sound velocity value for each focal point. Echo signals are reconstructed to generate a B-mode image, the thickness of subcutaneous fat (and muscle thickness, if necessary) contained in the B-mode image is measured, and the optimal sound velocity value for each focal point is set according to the measured fat thickness (and muscle thickness, if necessary). In another embodiment of the present invention, the phase difference of the echo signals is determined taking into account the difference in the measured fat thickness (and muscle thickness, if necessary). The sound velocity value (delay time correction value) is automatically changed according to this determined phase difference of the echo signals.

[0052] In this embodiment, software (program) is executed by a processor including a CPU 120 to configure 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 or on a recording medium such as a flash memory or a DVD-ROM.

[0053] The above description focuses on the most preferred embodiment of the present invention, but as will be apparent to those skilled in the art, 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 Oscillator 112 Signal 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 Optimal sound velocity value setting section 129 Sound velocity 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 line 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 echo signals from a subject, an ultrasound 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 the sound velocity value in the local region so as to be different from the sound velocity value in a region other than the local region based on the position information when reconstructing the echo signals to reconstruct an ultrasound image; an image generating unit that displays a plurality of image items that are candidates for the local area superimposed on the ultrasound image; Equipped with the localized region is localized in both the azimuth direction and the depth direction; the plurality of image items are arranged in the azimuth direction and the depth direction; An ultrasound diagnostic device, wherein the position information of the local region is designated in response to selection of one or more of the plurality of image items.

2. The change in the sound velocity value is performed according to a manual instruction from an operator, The manual designation is: a slide operation by an operator on a slide bar displayed on a display device of the ultrasonic diagnostic device; and a numerical input by the operator into a dialog box displayed on a display device of the ultrasonic diagnostic device. 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 location specification history of the location information of the local area; A history of manual sound speed specification of the sound speed value in the local region; a designation history storage unit that stores the designation history in association with each other; The signal processing means Returning the setting of the sound velocity value to one or more previous states for one or more local regions included in the past position specification history; saving the sound speed value settings for one or more local regions included in the past position specification history; Loading previously set sound speed values ​​for one or more local regions included in the past position specification 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 area is calculated based on a phase difference between elements of an ultrasonic probe corresponding to the local area in a received signal.

6. The ultrasound diagnostic apparatus according to claim 1 , wherein the size and / or number of the plurality of image items can be changed automatically or manually.

7. 2. The ultrasound diagnostic device of claim 1, wherein in response to selection of one or more of the plurality of image items, a display manner of the selected one or more plurality of image items is changed so that the selected one or more plurality of image items can be distinguished from the other one or more plurality of image items that have not been selected.

8. 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 ​​in the local area; 7. The ultrasound diagnostic device according to claim 1, wherein the ultrasound image of the region other than the local region is generated by reconstructing the echo signals using delay amounts or sound speed parameters corresponding to sound speed values ​​in the region other than the local region.

9. A program for generating an ultrasound image based on an echo signal from a subject, receiving the echo signals; a step of displaying a plurality of image items superimposed on the ultrasound image, the plurality of image items being arranged in an azimuth direction and a depth direction; In response to an operator selecting one or more of the plurality of image items, receiving position information of a local region of the ultrasound image corresponding to the selected one or more image items; When reconstructing the echo signals to reconstruct an ultrasound image, changing the sound velocity value in the local region based on the position information so that it is different from the sound velocity value in a region other than the local region; to a processor, The local region is local in both the azimuth direction and the depth direction.

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