Ultrasonic diagnostic device capable of changing sound velocity value in local region

Abstract

Provided is an ultrasonic diagnostic device capable of changing the sound velocity value in a local region. An ultrasound diagnostic device (100) of the present disclosure generates an ultrasound image (144) on the basis of an echo signal (142) from a subject (BD). An ultrasound diagnostic device (100) is provided with: an ultrasound probe (110) that receives an echo signal (142); an interface capable of specifying position information of a local region of the ultrasound image by an operator; and a signal processing means (120) that, when reconstructing the echo signal (142) and reconstructing the ultrasonic image (144), changes the sound velocity value of the local region so as to differ from the sound velocity value of a region other than the local region on the basis of the position information. The local region is local in both the azimuth direction (X) and the depth direction (Y).

Description

Technical Field

[0001] The present disclosure relates to an ultrasonic diagnostic device that adjusts the sound velocity value of a specific local area to display an ultrasonic image after the sound velocity is adjusted. In particular, the ultrasonic diagnostic device adjusts the sound velocity value of the specific local area to be different from the sound velocity value outside the specific local area and displays the ultrasonic image after the sound velocity is adjusted. Background Art

[0002] The ultrasonic diagnostic apparatus transmits ultrasonic waves to the biological tissue of a subject from an ultrasonic probe having a plurality of ultrasonic transducers. The ultrasonic echo signals are received by the plurality of ultrasonic transducers of the ultrasonic probe, and an ultrasonic image is created based on the received echo signals.

[0003] The echo signals received by each ultrasonic transducer are input to a receive beamformer. The receive beamformer performs receive beamforming on the echo signals received by each ultrasonic transducer. The receive beamforming includes a phase modulation and addition process of delaying and adding the echo signals received by each ultrasonic transducer.

[0004] The delay time in receive beamforming is set by assuming that the sound velocity of ultrasound in biological tissue is a specified value (for example, 1530 m / s). However, the sound velocity value of ultrasound in biological tissue sometimes differs depending on the subject or part. For example, the sound velocity in muscle is sometimes 1590 m / s, and the sound velocity in bone is sometimes 3000 m / s. If the sound velocity value set based on the delay time is different from the actual sound velocity value, the receive focus may be degraded. If the sound velocity value set based on the delay time is different from the actual sound velocity value, the spatial resolution is degraded and the preferred contrast cannot be obtained.

[0005] In connection with this problem, Japanese Patent Publication No. 8-308832 provides an ultrasonic diagnostic apparatus that displays patterns corresponding to different diagnostic parts of a subject and to the layered tissue structure of the diagnostic parts, and an examiner can manually (by hand) change the sound velocity of an ultrasonic signal suitable for each layered tissue structure.

[0006] However, the change of the sound velocity based on the layer may not always meet the needs of the examiner. For example, sometimes lesions such as tumors and blood vessels have sound velocity values ​​different from those of surrounding tissues. On the other hand, lesions such as tumors and blood vessels may not necessarily become layered structures in ultrasound images. Therefore, even if the examiner manually changes the sound velocity in 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 the preferred image quality.

[0007] Japanese Patent Application Laid-Open No. 6-304172 provides a user interface for the examiner to manually change the sound speed in each of a plurality of ultrasonic transducers. Even in this case, for example, if there are a plurality of structures that the examiner wants to observe along the same ultrasonic transducer, sometimes all of them cannot be displayed with a good image quality.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Laid-Open No. 8-308832

[0011] Patent Document 2: Japanese Patent Application Laid-Open No. 6-304172

[0012] Patent Document 3: Japanese Patent Application Laid-Open No. 2-274235 Summary of the invention

[0013] Problem that the invention aims to solve

[0014] Therefore, an ultrasonic diagnostic apparatus is desired that can easily change the sound velocity of a local area desired by an examiner in an intuitive and easy-to-understand manner.

[0015] Technical Solution

[0016] An ultrasonic diagnostic apparatus according to a first aspect is an ultrasonic diagnostic apparatus for generating an ultrasonic image based on an echo signal from a subject, and comprises: an ultrasonic probe for receiving the echo signal; an interface for enabling an operator to specify position information of a local area of ​​the ultrasonic image; and a signal processing unit for changing a sound velocity value of the local area to be different from a sound velocity value of an area other than the local area based on the position information when reconstructing the ultrasonic image by reconstructing the echo signal. Here, the local area is local in both the azimuth direction and the depth direction.

[0017] In the ultrasonic diagnostic apparatus of the second aspect, the sound velocity value is changed according to manual designation by the operator, and the manual designation is performed according to any one or more 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.

[0018] The ultrasonic diagnostic apparatus of the third aspect further comprises a designation history storage unit that stores the following in association with each other: the past position designation history of the position information of the local area; and the past manual sound speed designation history of the sound speed information of the local area. In addition, the signal processing unit is configured to perform one or more of the following: returning the setting of the sound speed information to one or more previous states for one or more local areas included in the past position designation history; saving the setting of the sound speed information for one or more local areas included in the past position designation history; and loading the sound speed information set in the past for one or more local areas included in the past position designation history.

[0019] In the ultrasonic diagnostic apparatus according to 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 area.

[0020] In the ultrasonic diagnostic apparatus according to the fifth aspect, the signal processing unit calculates the sound velocity value of the local area based on the phase difference between elements of the reception signals of the elements of the ultrasonic probe corresponding to the local area.

[0021] The ultrasonic diagnostic apparatus of the sixth aspect further comprises an image generating unit for superimposing and displaying a plurality of image items as candidates for the local region on the ultrasonic image. The plurality of image items are arranged in the azimuth direction and the depth direction, and in response to selecting one or more of the plurality of image items, position information of the local region is specified.

[0022] In the ultrasonic diagnostic apparatus according to the seventh aspect, the size and / or number of the plurality of image items can be changed automatically or manually.

[0023] In the ultrasonic diagnostic apparatus according to the eighth aspect, in response to selection of one or more of the plurality of image items, the display form of the selected one or more of the plurality of image items is changed so as to be recognizable from the other one or more of the plurality of image items that are not selected.

[0024] In the ultrasonic diagnostic device of the ninth aspect, the signal processing unit is configured to reconstruct the echo signal by using the delay amount or sound speed parameter corresponding to the sound speed value of the local area to generate an ultrasonic image of the local area, and to reconstruct the echo signal by using the delay amount or sound speed parameter corresponding to the sound speed value of the area outside the local area to generate an ultrasonic image of the area outside the local area.

[0025] In the tenth aspect, a program is provided for generating an ultrasonic image based on an echo signal from a subject. The program causes a processor to perform the following steps: receiving an echo signal; receiving position information of a local area of ​​the ultrasonic image based on a designation by an operator; and when reconstructing the ultrasonic image by reconstructing the echo signal, changing the sound velocity value of the local area to be different from the sound velocity value of an area outside the local area based on the position information. Here, the local area is local in both the azimuth direction and the depth direction. In addition, in the eleventh aspect, a non-temporary storage medium is provided for storing the program provided in the tenth aspect.

[0026] Beneficial Effects

[0027] The present invention has been made in view of such circumstances, and can change the speed of sound of a local area desired by an examiner simply, intuitively, and easily understood. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a block diagram showing the configuration of the ultrasonic diagnostic apparatus 100 according to the embodiment.

[0029] Figure 2 This is a conceptual diagram showing the focal position inside a subject when linear scanning is performed in the azimuth direction according to the embodiment.

[0030] Figure 3 FIG. 1 is a diagram showing a user interface that allows an operator to designate position information and a sound velocity value of a local region of an ultrasonic image according to the embodiment.

[0031] Figure 4 This is a conceptual diagram in the case of using a plurality of position specific icons arranged in the depth direction and the azimuth direction according to the embodiment. DETAILED DESCRIPTION

[0032] Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0033] Figure 11 is a block diagram showing the structure of an ultrasonic diagnostic apparatus 100 according to a specific embodiment of the present invention. The ultrasonic diagnostic apparatus 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 apparatus 100 includes a transmission control unit 112, a reception control unit 113, a transmission delay amount (mode) storage unit 114, and a reception delay amount (mode) storage unit 115. In addition, the ultrasonic diagnostic apparatus 100 includes an input unit 131 and a display unit 133. The input unit 131 can receive input from an operator, for example, receive input of information such as instructions, positions, and numerical values ​​from an operator (operator) via a graphical user interface (GUI). The input unit 131 is configured to include a keyboard, hard keys, and soft keys. The input unit 131 may also include various input devices such as a pointing device such as a mouse, a touch panel, a pen tablet, a touchpad, a track ball, a joy stick, eye tracking, and voice input. The display unit 133 may also include a display device such as an LCD (Liquid Crystal Display), a head mount display such as a glasses type or a goggle type, and a projector.

[0034] The ultrasonic probe (probe) 110 includes a plurality of elements (vibrators) 111 constituting a one-dimensional or two-dimensional transducer array. These plurality of elements 111 transmit ultrasonic waves into the body based on a driving signal applied from a transmission control unit 112, receive ultrasonic echoes (echo signals) reflected in the body, and output the received signals to a reception control unit 113. In order to make it easier for readers to understand, the azimuth direction ( Figure 1 Although nine elements 111 are shown in a simplified manner in the X direction, in reality, 16 to 4000 elements 111, preferably 100 to 2500 elements 111, and more preferably about 2000 elements 111 can be configured in one ultrasonic probe 110. Figure 1 X direction) and depth direction ( Figure 1In the Z direction orthogonal to the Y direction, 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.

[0035] Each element 111 is a vibrator made of a piezoelectric material (piezoelectric body) such as piezoelectric ceramics and polymer piezoelectric elements. Each element 111 generates pulsed or continuous wave ultrasonic waves, and an ultrasonic beam is formed by synthesizing these ultrasonic waves. In addition, the multiple elements 111 expand and contract by receiving ultrasonic echoes reflected from the BD in the subject, generating electrical signals. These electrical signals are output to the reception control unit 113 as reception signals of ultrasonic echoes.

[0036] Each element 111 is in contact with the surface of the subject BD. Figure 1 In the embodiment of the present invention, the subject BD includes subcutaneous fat B1, muscle B2, and liver B3. However, the inspection site does not necessarily include the liver B3 of the subject BD. The inspection object can be the structure of all inspection sites of the subject BD that are the inspection objects using the ultrasonic diagnostic apparatus. In addition, the subject BD can be not only the human body but also a living thing other than humans, such as livestock, pets, and experimental animals.

[0037] 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 a pattern from the plurality of delay amounts stored in the transmission delay amount storage unit 114 according to the transmission direction set in the scanning control unit 11, and sets the delay time of the driving signal provided to each of the plurality of elements 111 based on the delay amount. Thus, the ultrasonic beams transmitted from the plurality of elements 111 at once reach the entire imaging area of ​​the subject.

[0038] The reception delay amount (mode) storage unit 115 stores a plurality of reception delay amounts used when performing focusing processing on a plurality of reception signals output from a plurality of elements 111. The reception control unit 113 selects a delay amount from the plurality of reception delay amounts stored in the reception delay amount storage unit 115, and based on the reception delay amount and the speed of sound in the subject, delays the plurality of reception signals and adds them together. Thus, reception focusing processing is performed. Through the focusing processing, a focused and reduced echo signal of the ultrasonic echo is generated. Furthermore, the reception control unit 113 performs envelope detection processing on the formed echo signal. The echo signal is stored in the echo signal memory 142 in the memory 140.

[0039] Here, the delay amount of the received signal is determined based on the speed of sound in the subject BD. Generally, as an average speed of sound value in the human body, it is set to 1530 to 1540 m / s. However, in reality, the speed of sound value varies depending on the tissue in the subject BD. Generally, in the subcutaneous fat B1, the speed of sound value is set to about 1450 m / s, and in the muscle B2 or the liver B3, the speed of sound value is set to about 1550 m / s. However, these numerical values ​​are general values ​​and sometimes vary depending on the subject. For example, the speed of sound value becomes faster in a liver that becomes cirrhotic, and the speed of sound value becomes slower in a liver that becomes fatty liver. In this embodiment, the receiving delay amount storage unit 115 stores, for example, delay amounts of 1000 m / s to 3000 m / s, and more preferably stores delay amounts of 1430 m / s to 1580 m / s.

[0040] The CPU 120 includes an image generator 121, an optimal sound velocity value setting unit 123, and a sound velocity value calculation unit 129. The image generator 121 generates a B-mode image as tomographic image information related to the tissue 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. Figure 1 In the example of FIG. 1 , the B-mode image 144 is taken as an example for explanation, but the present invention can also be applied to reconstruction of images in other modes.

[0041] The optimal sound velocity value setting unit 123 sets the sound velocity value optimal for image display of a specific part automatically based on the delay amount of the received signal and the echo signal 142 or using the B-mode image of the image generating unit 121 or based on the delay amount of the received signal and the sound velocity designation information from the input unit 131 .

[0042] In a specific embodiment of the present invention, the sound velocity value calculation unit 129 specifies the phase of the echo signal 142 and specifies the difference in the sound velocity of each sound ray. In another embodiment, the sound velocity value calculation unit 129 analyzes the B-mode image 144 and estimates the sound velocity value for each sound ray by specifying the type and size of the tissue included in the B-mode image 144.

[0043] In this embodiment, the software (program) is executed by a processor having a CPU 120 to form a signal processing unit including an image generation unit 121, an optimal sound speed value setting unit 123, and a sound speed value calculation unit 129. The software is stored in a memory 140. In addition to a built-in hard disk, the software can also be recorded in a recording medium such as a flash memory or a DVD-ROM. It can also be embodied using a smartphone. Figure 1 Part or most of the functional blocks shown may be embodied using a plurality of computers that are connected via a network and exist in remote locations.

[0044] Figure 2 1 is a diagram showing the focal position inside the subject BD when linear scanning is performed in the azimuth direction X. In this embodiment, as in conventional linear electronic scanning, the aperture positions 211, 221 to 2n1 for transmitting and receiving waves of the element array 111 are sequentially moved, and the focal positions 213, 223 to 2n3, 215, 225 to 2n5 for transmitting and receiving waves are sequentially moved to perform scanning, thereby obtaining a tomographic image. According to the conventional linear electronic scanning method, by controlling the aperture position and the delay amount in each aperture, a desired number of focal points can be set at desired positions (depth direction positions and azimuth direction positions).

[0045] Figure 3 An example of a user interface in which an operator can specify position information and sound velocity values ​​of a local area of ​​an ultrasound image in a preferred embodiment of the present invention is shown. As shown in the figure, a B-mode image 301 of a subject BD currently being examined is displayed on the display unit 133. If the operator selects an icon displayed as "Local sound velocity setting" on the screen (not shown), depth direction boundary lines 311, 313, 315 and azimuth direction boundary lines 321, 323, 325, 327 are displayed overlapping with the B-mode image 301. Figure 3 In the example of FIG. 3 , the depth direction boundary lines 311 , 313 , 315 extend radially according to the scanning cross section of the fan-shaped expanded B-mode image. In other embodiments, the depth direction boundary lines 311 , 313 , 315 extend in a direction orthogonal to the azimuth direction boundary lines 321 , 323 , 325 , 327 . Figure 3 In the example of FIG. 1 , the azimuth boundary lines 321, 323, 325, and 327 extend in a straight line in a manner perpendicular to the depth boundary line 313 located in the center. In other embodiments, the azimuth boundary lines 321, 323, 325, and 327 extend in a curved shape that constitutes a part of a concentric circle according to the scanning cross section of the fan-shaped B-mode image.

[0046] The number, position, and shape of the depth direction boundary lines 311, 313, 315 and the azimuth direction boundary lines 321, 323, 325 can be implemented with various changes as needed. In a preferred embodiment of the present invention, the number, position, and shape of the depth direction boundary lines 311, 313, 315 and the azimuth direction boundary lines 321, 323, 325 can be set by the operator on the screen. For example, the number of the depth direction boundary lines 311, 313, 315 and the azimuth direction boundary lines 321, 323, 325 can be any natural number in the range of 1 to 100, respectively. Preferably, the number of the depth direction boundary lines 311, 313, 315 and the azimuth direction boundary lines 321, 323, 325 can be any natural number in the range of 3 to 20, respectively.

[0047] In addition, the depth-direction boundary lines 311, 313, 315 and the azimuth-direction boundary lines 321, 323, 325 do not have to be uniform over the entire B-mode image 301, and may be dense in a specified portion and sparse in other portions. For example, the Japanese Digestive Organ Cancer Diagnosis Society has determined 25 recommended recording sections (ultrasonic B-mode images), and in each of the sections, the operator determines the position and direction in which the ultrasonic probe 110 is configured on the subject BD. In this case, sometimes, for example, the bile duct is focused on in the 14th section among the 25 sections, and on the other hand, the approximate position in the B-mode image 301 where the bile duct exists is known. At a position where the possibility of the presence of the bile duct is high, one or both of the depth-direction boundary lines 311, 313, 315 and the azimuth-direction boundary lines 321, 323, 325 can be dense and sparse in other portions. In other embodiments, the internal organs included in the B-mode image are automatically detected, and the depth direction boundary lines 311 , 313 , 315 and the azimuth direction boundary lines 321 , 323 , 325 are arranged according to the detection results.

[0048] exist Figure 3 In the embodiment, the region where the sound velocity value is changed is demarcated by the depth direction boundary lines 311, 313, 315 and the azimuth direction boundary lines 321, 323, 325, 327, but the region in the B-mode image can be identified using various known methods. Figure 4 This is an embodiment in which a plurality of position specific 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 specific icons 401 may also be fixed (the position, shape, and number cannot be changed). In other embodiments, the position, shape, and number of the plurality of position specific icons 401 can be changed according to the designation of the operator. Furthermore, in other embodiments, the position, shape, and number of the plurality of position specific icons 401 are automatically changed according to the type of B-mode image. For example, sometimes the fourth section in the 25 recommended recorded sections of the Japanese Digestive Organ Cancer Diagnosis Society pays attention to the abdominal aorta, and on the other hand, the approximate position in the B-mode image 301 where the abdominal aorta exists is known. At a position where the abdominal aorta is likely to exist, the plurality of position specific icons 401 are displayed in a manner in which the position specific icon 401 with a shape covering the abdominal aorta is arranged. In other embodiments, the internal organs included in the B-mode image are automatically detected, and the plurality of position specific icons 401 are arranged according to the detection results.

[0049] The positions, shapes, and numbers of the plurality of location specific icons 401 can be changed using various methods. For example, if any location specific icon 401 is continuously selected for a predetermined time, the operator can select and display a list for selecting various shapes of the location specific icon 401, such as a circle, a rectangle, a sector, and an ellipse. In addition, if two location specific icons 401 separated in the azimuth direction are contracted inward, the number of the location specific icons 401 in the azimuth direction can be increased, and if two location specific icons 401 separated in the azimuth direction are contracted outward, the number of the location specific icons 401 in the azimuth direction can be reduced. If two location specific icons 401 separated in the depth direction are contracted inward, the number of the location specific icons 401 in the depth direction can be increased, and if two location specific icons 401 separated in the depth direction are contracted outward, the number of the location specific icons 401 in the depth direction can be reduced. If two location specific icons 401 separated in both the azimuth direction and the depth direction are contracted inward, the number of location specific icons 401 in both the azimuth direction and the depth direction can be increased at the same time, and if two location specific icons 401 separated in both the azimuth direction and the depth direction are contracted outward, the number of location specific icons 401 in both the azimuth direction and the depth direction can be reduced at the same time. Furthermore, if each location specific icon 401 is contracted inward, the location specific icon 401 can be made smaller, and if each location specific icon 401 is contracted outward, the location specific icon 401 can be made larger.

[0050] exist Figure 3In the example, if an area where the sound velocity value is desired to be changed is selected, a selection display icon 331 is displayed on the selected area. The selection of the area is performed by the input unit 131. The selection using the input unit 131 includes selection using a pointing device such as a mouse, a touch panel, a handwriting tablet, a touch pad, a trackball, a joystick, or a keyboard input. In the case where the input using the input unit 131 is a keyboard input, the area is selected by moving the area selected using the label key in sequence and inputting the number assigned to each area. In addition, instead of a pointing device, keyboard input, or in combination with these, the area can be selected by various input devices such as eye tracking and voice input. In this embodiment, the selection display icon 331 is selected so that when a pebble is thrown into a pond, ripples expand on the water surface, and a plurality of concentric circles are expanded only in the selected area at a specified speed, and the range (boundary) of the selected area is clearly indicated to the operator. In other embodiments, the selected area is displayed changed using a specified color, shadow, contrast change, flashing, etc., and the range (boundary) of the selected area is clearly indicated to the operator. Furthermore, in other embodiments, the selection area uses a specified color, shadow, flicker, etc. to display the outer periphery of the selection area, and the scope (boundary) of the selection area is clearly indicated to the operator. Further, in other embodiments, the display of the selection area does not change, and the area outside the selection area uses a specified color, shadow, contrast change, flicker, etc. to display the change, and the scope (boundary) of the selection area is clearly indicated to the operator. That is, in response to selecting one or more of the multiple image items, the display method of the selected one or more multiple image items is changed so that they can be identified from the other one or more multiple image items that have not been 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" mentioned here. The selected area is local or limited in both the azimuth direction and the depth direction. The size and / or number of multiple image items can be changed automatically or manually.

[0051] exist Figure 4In the B-mode image 144, if a position-specific icon 401 corresponding to an area in which a change in the sound velocity value is desired is selected, the selected position-specific icon 401 is changed to a selected display icon 403. The selected display icon 403 can be identified from the position-specific icon 401 in terms of color, shape, pattern, flashing, etc. That is, in response to selecting one or more of the plurality of image items, the display method of the selected one or more of the plurality of image items is changed so that it can be identified from the other one or more of the plurality of image items that are not selected. The position-specific icon 401 corresponds to the "image item" mentioned here. The position-specific icon 401 is local or limited in both the azimuth direction and the depth direction. The image generation unit 121 displays the plurality of image items as candidates for the local area in an overlapping manner on the B-mode image 144. The plurality of image items are arranged in the azimuth direction and the depth direction, and in response to selecting one or more of the plurality of image items, the position information of the local area is specified.

[0052] The selection of the position specific icon 401 is performed by the input unit 131. The selection using the input unit 131 includes selection using a pointing device such as a mouse, a touch panel, a handwriting tablet, a touch pad, a trackball, a joystick, or a keyboard input. In the case where the input using the input unit 131 is a keyboard input, the selection of the area is performed by sequentially moving the position specific icon 401 selected using the label key and inputting the number assigned to each position specific icon 401 using the key. In addition, instead of or in combination with the pointing device and keyboard input, the selection of the position specific icon 401 can be performed using various input devices such as eye tracking and voice input. In a certain embodiment, the selected area is only the area within the selected display icon 403. In other embodiments, the selected area includes not only the area within the selected display icon 403 but also the area outside it.

[0053] exist Figure 3In the example, if the area where the sound velocity value is desired to be changed is selected, the 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. If the operator moves the slide handle 343 to the right, the sound velocity becomes faster, and if the operator moves the slide handle 343 to the left, the sound velocity becomes slower. In a preferred embodiment of the present invention, it is possible to adjust the sound velocity according to a prescribed linear function between 1000m / s and 2000m / s with 1500m / s as the center. In other embodiments of the present invention, it is possible to adjust the sound velocity according to a prescribed nonlinear function between 1200m / s and 3000m / s with 1530m / s as the center. In this example, a function including the following curve is selected: near the center, there is a proportional relationship between the moving distance from the center and the change in the sound velocity, but, for example, near the right end, the change in the sound velocity relative to the moving distance becomes a very large value. In a specific embodiment of the present invention, in response to the operator moving the sliding handle 343 to the right, the signal processing unit 120 causes the speaker (not shown) to produce high sounds corresponding to fast sound speeds, and in response to the operator moving the sliding handle 343 to the left, the signal processing unit 120 causes the speaker to produce low sounds corresponding to slow sound speeds.

[0054] In a specific embodiment of the present invention, in addition to or in place of the slider icon 341, a dialog box such as a rotary box 351 and a dialog icon assigned to each of the thousands to units digits is displayed on the display unit 133. The numerical value displayed in the rotary box 351 is linked to the position of the slide handle 343 in the slider icon 341. If the slide handle 343 moves, the sound speed value corresponding to the moved position is displayed in the rotary box 351. The numerical value of the rotary box 351 can be changed by operating the updown buttons (up and down buttons) 353 and 355 located at the right end of the rotary box 351, and the position of the slide handle 343 of the slider icon 341 also automatically moves accordingly. The numerical value of the rotary box 351 can also be changed by using the numerical input (e.g., keyboard input, voice input) of the input unit 131.

[0055] In certain embodiments of the present invention, a load button 361, a cancel button 363, and a save button 365 are displayed on the display 133. Figure 3As described, if an area in which a change in the sound velocity value is desired is selected, the selection display icon 331 is displayed on the selected area. If the load button 361 is selected in this state, the information stored in the designated history storage unit 146 can be selectively referenced. The sound velocity values ​​set in the past in each area are stored in the designated history storage unit 146. Specifically, the sound velocity values ​​of 1 to 100 set in the past are stored for each area. More preferably, the sound velocity values ​​of 2 to 10 set in the past are stored for each area. In a specific embodiment of the present invention, the upper limit of the number of sound velocity values ​​that can be stored in each area is different. In a specific embodiment of the present invention, if the load button 361 is pressed once, the sound velocity value set most recently is called out and displayed in the rotating box 351, and the slider icon 341 is also linked to the value. If, for example, the load button 361 is pressed three times, the sound velocity value set three times ago is called out and displayed in the rotating box 351, and the slider icon 341 is also linked to the value. In a specific embodiment of the present invention, if the load button 361 is pressed more than once, the sound velocity values ​​set in the past are called out and displayed as a list. If the operator selects a desired value from the list, the selected value is displayed in the rotating box 351, and the slider icon 341 is also linked to the value. The sound velocity values ​​displayed as a list can be modified / deleted. In a specific embodiment of the present invention, if the load button 361 is selected without selecting an area where a change in the desired sound velocity value is desired, a display and / or sound is provided to the operator to prompt the selection of an area where a change in the desired sound velocity value is desired.

[0056] In a specific embodiment of the present invention, after selecting a region where a sound velocity value is desired to be changed and setting a sound velocity value suitable for the selected region, if the save button 365 is selected, the position information of the local region of the ultrasonic image and the sound velocity value set corresponding thereto are sent to the image generator 121. The region where the sound velocity value is desired to be changed does not have to be a single region, and any continuous multiple regions or multiple regions separated from each other can be selected, and the sound velocity value common to these multiple regions can be set. The image generator 121 that receives the position information of the local region of the ultrasonic image and the sound velocity value set corresponding thereto reconstructs the image based on the position information of the local region of the ultrasonic image and the sound velocity value set corresponding thereto. More specifically, the image generator 121 specifies all the focal points corresponding to the position information of the local region of the ultrasonic image, and uses the sound velocity value set in the receive beamforming in all the specified focal points. When performing a phase modulation and addition process of delaying and adding the echo signals received in each ultrasonic vibrator, the 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 receiving delay amount storage unit 115 is updated to the position information of the local area of ​​the ultrasonic image received by the image generating unit 121 and the sound velocity value set accordingly. In a specific embodiment of the present invention, the pattern of the delay amount stored in the transmitting delay amount storage unit 114 is updated to the position information of the local area of ​​the ultrasonic image received by the image generating unit 121 and the sound velocity value set accordingly. In a specific embodiment of the present invention, the sound velocity value set in each area in the past stored in the designated history storage unit 146 is updated according to the position information of the local area of ​​the ultrasonic image received by the image generating unit 121 and the sound velocity value set accordingly. In the local area designated by the operator, the delay amount is changed according to the sound velocity value designated as described above, but the sound velocity value in the area outside the local area remains unchanged. Thus, the sound velocity value of the local area can be changed in a manner different from the sound velocity value of the area outside the local area. The local area is local in both the azimuth direction and the depth direction.

[0057] In a specific embodiment of the present invention, a B-mode image 144 covering the entire area is generated by each of the sound velocity values ​​of the local area and the sound velocity values ​​of the area other than the local area, and these are cut and pasted to be synthesized. Sometimes, this cutting and pasting is performed on two B-mode images 144 as objects, but when a combination of multiple local areas and sound velocity values ​​is set, three or more B-mode images 144 are cut and pasted as objects. The B-mode image 144 that is the object of cutting and pasting does not need to be a B-mode image 144 covering the entire area, and as long as it covers the necessary area, it can also be a local image in the azimuth direction, the depth direction, or both.

[0058] In a specific embodiment of the present invention, once the save button 365 is selected, the designated sound velocity value can be canceled by pressing the cancel button 363. The most recent sound velocity value (the sound velocity value before the save button 365 is selected) and the position information of the local area stored in the designated history storage unit 146 are sent to the image generation unit 121. The image generation unit 121, which receives the position information of the local area of ​​the ultrasonic image and the sound velocity value set corresponding to it, reconstructs the image based on the position information of the local area of ​​the ultrasonic image and the sound velocity value set corresponding to it. More specifically, the image generation unit 121 specifies all the focal points corresponding to the position information of the local area of ​​the ultrasonic image, and uses the sound velocity value set in the receive beamforming in all the specified focal points. When performing the phase modulation and addition processing of delaying and adding the echo signals received in each ultrasonic vibrator, the 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 ultrasonic image received by the image generation unit 121 and the sound velocity value set corresponding to it. In a specific embodiment of the present invention, the pattern of the delay amount stored in the transmission delay amount storage unit 114 is updated with the position information of the local area of ​​the ultrasonic 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 image generation unit 121 updates the sound velocity value set in the past in each area stored in the designated history storage unit 146 to delete the sound velocity value when the save button 365 is pressed in the local area. In a specific embodiment of the present invention, by pressing the cancel button 363 multiple times, the setting of the sound velocity information can be returned not only to the previous state but also to the previous two or more states.

[0059] return Figure 2 To explain further, the human body as the subject is usually close to the surface of the probe element array 111, such as skin, fat, muscle, organ parenchyma, etc., and the tissues with different sound velocities are as follows: Figure 2 The delay time correction values ​​are greatly different at the shallow focus position 213 and the deep focus position 215 in the aperture position 211, but the distribution of the delay time correction values ​​corresponding to the focal points 223 and 225 of the same focal length at the adjacent aperture position 221 generally becomes values ​​very close to the correction values ​​corresponding to the focal lengths 213 and 215, respectively. Based on this feature, the distribution of the optimal delay time correction values ​​initially obtained for each focal length at the aperture position 211 can be used as the initial value of the sequence for optimizing the delay time correction values ​​at the adjacent aperture position 221.

[0060] However, even if the echo signals are from the same focal length of the focal points at the aperture positions close to each other, the sound velocity values ​​of the ultrasonic waves propagating in the biological tissues may be different. If the sound velocity value set based on the delay time is different from the actual sound velocity value, the receiving focus is degraded, the spatial resolution is degraded, and the optimal contrast cannot be obtained.

[0061] When there is a difference in the sound velocity value of the ultrasonic wave propagating in the biological tissue between two echo signals from the same focal length of the aperture position close to each other, the phases of the two echo signals are different. By automatically changing the sound velocity value (delay time correction value) according to the degree of difference in the phase of the echo signal, the spatial resolution can be improved and a preferred contrast can be obtained. In one embodiment of the present invention, the phases of n echo signals from the same focal length 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 in the range of 3 to 1000. More preferably, n can be a predetermined natural number in the range of 10 to 500. In other embodiments of the present invention, the value of n can be manually changed by the operator. In addition, the echo signal whose phase difference degree is outside the range of the predetermined deviation value of ±0.1σ to ±4σ can be used as the object of automatic sound velocity value change. Preferably, the echo signal whose phase difference degree is outside the range of the predetermined deviation value of ±0.5σ to ±2σ can be used as the object of automatic sound velocity value change. More preferably, the echo signal whose phase difference is outside the range of ±1σ can be made a target for automatic sound velocity value change. In another embodiment of the present invention, the value of the predetermined deviation value can be manually changed by an operator.

[0062] In other embodiments of the present invention, when setting the sound velocity value for each focus, the invention described in Japanese Patent No. 6081744 is used. The echo signal is reconstructed to generate a B-mode image, the thickness of the subcutaneous fat (including the thickness of the muscle as needed) included in the B-mode image is measured, and the optimal sound velocity value for each focus is set based on the measured fat thickness (including the thickness of the muscle as needed). In other embodiments of the present invention, the phase difference of the echo signal is determined in consideration of the difference in the measured fat thickness (including the muscle thickness as needed). Based on the determined phase difference of the echo signal, the sound velocity value (delay time correction value) is automatically changed.

[0063] In this embodiment, the software (program) is executed by the processor provided with the CPU 120 to constitute the image generation unit 121, the optimal sound speed value setting unit 123, and the sound speed value calculation unit 129. The software is stored in the memory 140. In addition to the built-in hard disk, the software can also be recorded in a recording medium such as a flash memory and a DVD-ROM.

[0064] Although the best mode for carrying out the present invention has been mainly described above, it will be apparent to those skilled in the art that various changes and modifications can be made to the embodiments within the technical scope of the present invention.

[0065] Description of Reference Numerals

[0066] 100: Ultrasonic diagnostic equipment

[0067] 110: Ultrasonic probe

[0068] 111: Vibrator

[0069] 112: Sending control unit

[0070] 113: Receiving control unit

[0071] 114: Transmission delay amount (mode) storage unit

[0072] 115: Receiving delay amount (mode) storage unit

[0073] 120: CPU / Signal processing unit / Signal processing unit

[0074] 121: Image generation unit

[0075] 123: Optimal sound velocity value setting unit

[0076] 129: Sound velocity calculation unit

[0077] 131: Input

[0078] 133: Display unit

[0079] 140: Memory

[0080] 142: Echo signal

[0081] 144, 301: B-mode images

[0082] 146: Designation of history storage unit

[0083] 211, 221~2n1: aperture position

[0084] 213, 223~2n3, 215, 225~2n5: focal position

[0085] 311, 313, 315: Depth boundary lines

[0086] 321, 323, 325, 327: Azimuth direction boundary lines

[0087] 331, 403: Select the display icon

[0088] 341: Slider Icon

[0089] 343: Sliding handle

[0090] 351: Rotating box

[0091] 353: Up button

[0092] 355: Down button

[0093] 361: Loading button

[0094] 363: Cancel button

[0095] 365: Save button

[0096] 401: Location Specific Icon

Claims

1. An ultrasonic diagnostic apparatus for generating an ultrasonic image based on an echo signal from a subject, comprising: an ultrasonic probe for receiving the echo signal; An interface capable of allowing an operator to specify position information of a local area of ​​an ultrasonic image; and a signal processing unit that, when reconstructing the echo signal to reconstruct the ultrasonic image, changes the sound velocity value of the local area to be different from the sound velocity value of the area other than the local area based on the position information, The local area is local in both the azimuth direction and the depth direction.

2. The ultrasonic diagnostic apparatus according to claim 1, wherein: The speed of sound value is changed according to the manual designation of the operator. The manual designation is performed according to any one or more of the following: The operator performs a sliding operation on a slide bar displayed on a display device of the ultrasonic diagnostic apparatus; and An operator inputs a numerical value into a dialog box displayed on a display device of the ultrasonic diagnostic apparatus.

3. The ultrasonic diagnostic apparatus according to claim 2, wherein: The device further comprises a designated history storage unit storing the following in association with each other: A past location specification history of the location information of the local area; and a past manual sound speed designation history of the sound speed information of the local area, The signal processing unit is configured to perform one or more of the following: For one or more local areas included in the past position specification history, returning the setting of the sound speed information to one or more previous states; A setting for storing sound speed information for one or more local areas included in the past position specification history; as well as For one or more local areas included in the past position specification history, the sound speed information set in the past is loaded.

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

5. The ultrasonic diagnostic apparatus according to claim 4, wherein: The signal processing unit The sound velocity value of the local area is calculated based on the phase difference between elements of the reception signals of the elements of the ultrasonic probe corresponding to the local area.

6. The ultrasonic diagnostic apparatus according to claim 1, wherein: The apparatus further comprises an image generating unit configured to display a plurality of image items as candidates for the local region by superimposing them on the ultrasonic image. The plurality of image items are arranged in the azimuth direction and the depth direction, In response to selecting one or more of the plurality of image items, the position information of the partial area is specified.

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

8. The ultrasonic diagnostic apparatus according to claim 6, wherein: In response to selection of one or more of the plurality of image items, the display form of the selected one or more of the plurality of image items is changed so as to be recognizable from the other one or more of the plurality of image items that are not selected.

9. The ultrasonic diagnostic apparatus according to any one of claims 1 to 7, wherein: The signal processing unit is composed of: reconstructing the echo signal by using a delay amount or a sound velocity parameter corresponding to the sound velocity value of the local area to generate an ultrasonic image of the local area, The echo signal is reconstructed using a delay amount or a sound velocity parameter corresponding to a sound velocity value of a region other than the local region, thereby generating an ultrasonic image of the region other than the local region.

10. A procedure, It generates an ultrasonic image based on the echo signal from the subject, The processor is caused to execute the following steps: receiving the echo signal; receiving position information of a local area of ​​the ultrasonic image based on a designation by an operator; and When reconstructing the echo signal to reconstruct the ultrasonic image, based on the position information, the sound velocity value of the local area is changed to be different from the sound velocity value of the area other than the local area, The local area is local in both the azimuth direction and the depth direction.

11. A non-transitory storage medium, The program according to claim 10 is stored.

Images