Ultrasonic diagnostic apparatus, program, and ultrasonic diagnostic method

Abstract

To provide an ultrasonic diagnostic apparatus and the like capable of obtaining an appropriate ultrasonic image without using a special auxiliary instrument during a tilting operation of an ultrasonic probe.SOLUTION: An ultrasonic diagnostic apparatus transmits ultrasonic waves into a subject, receives the ultrasonic waves reflected from a target tissue in the subject to obtain a received signal, and outputs an ultrasonic image of the target tissue on the basis of the received signal. The ultrasonic diagnostic apparatus comprises: an acquisition unit that acquires ultrasonic images of a plurality of frames when an angle of an ultrasonic probe is changed by the tilting operation of the ultrasonic probe; an extraction unit that extracts a reference frame including an ultrasonic image in a case where the ultrasonic probe and the target tissue are orthogonal from the plurality of frames acquired by the acquisition unit; and an output unit that outputs the reference frame extracted by the extraction unit.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an ultrasonic diagnostic apparatus, a program, and an ultrasonic diagnostic method. [Background technology]

[0002] In ultrasound examinations of the musculoskeletal system and anesthesia, fibrous tissues such as muscles, tendons, and nerve bundles are imaged. When imaging fibrous tissues, a tilting operation is performed in which the angle of the ultrasound probe is changed while the probe is pressed against the skin surface. If the angle of the ultrasound probe relative to the fibrous tissue during tilting operation is not appropriate, the tissue becomes anisotropic, from which no reflected signal can be obtained, and a high-brightness ultrasound image cannot be obtained.

[0003] As a technology for assisting the scanning of an ultrasound probe, there is a technology for acquiring information such as the position and posture of the ultrasound probe using an accessory device and attaching the acquired information to an ultrasound image. Examples of the accessory device include a GPS module or a multi-viewpoint camera (VR camera). Patent Document 1 describes an ultrasound diagnostic device that detects the position of an ultrasound probe in three-dimensional space using a position sensor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-49211 Summary of the Invention [Problem to be solved by the invention]

[0005] However, conventional technologies require additional equipment such as position sensors in addition to the ultrasound diagnostic device, making them difficult to operate during examinations and expensive.Furthermore, conventional technologies take into account the depth direction in three-dimensional space, and therefore cannot be applied to tilting operations, including translation of the ultrasound probe.

[0006] Therefore, in order to solve the above problems, an object of the present invention is to provide an ultrasonic diagnostic device, a program, and an ultrasonic diagnostic method that can acquire appropriate ultrasonic images when tilting an ultrasonic probe without using any special accessory equipment. [Means for solving the problem]

[0007] The ultrasonic diagnostic apparatus according to the present invention comprises: 1. An ultrasound diagnostic device that transmits ultrasound waves into a subject, receives the ultrasound waves reflected by target tissue in the subject to obtain received signals, and outputs an ultrasound image of the target tissue based on the received signals, an acquisition unit that acquires a plurality of frames of ultrasound images when the angle of the ultrasound probe is changed by tilting the ultrasound probe; an extracting unit that extracts a reference frame including an ultrasound image when the ultrasound probe and the target tissue are perpendicular to each other from the plurality of frames acquired by the acquiring unit; an output unit that outputs the reference frame extracted by the extraction unit; Equipped with.

[0008] The ultrasonic diagnostic apparatus according to the present invention comprises: 1. An ultrasound diagnostic device that transmits ultrasound into a subject, receives the ultrasound reflected by a target tissue in the subject to obtain a received signal, and outputs an ultrasound image of the target tissue based on the received signal, an acquisition unit that acquires a plurality of frames of ultrasound images when the angle of the ultrasound probe is changed by tilting the ultrasound probe; a setting unit that allocates angle information of the ultrasonic probe with respect to the skin surface of the subject during tilting operation to each of the plurality of frames; Equipped with.

[0009] The program according to the present invention comprises: a computer of an ultrasound diagnostic apparatus that transmits ultrasound waves into a subject, receives the ultrasound waves reflected by a target tissue in the subject to obtain a received signal, and outputs an ultrasound image of the target tissue based on the received signal; an acquisition unit that acquires a plurality of frames of ultrasound images when the angle of the ultrasound probe is changed by tilting the ultrasound probe; an extracting unit that extracts a reference frame including an ultrasound image when the ultrasound probe and the target tissue are perpendicular to each other from the plurality of frames acquired by the acquiring unit; an output unit that outputs the reference frame extracted by the extraction unit; Function as.

[0010] The ultrasonic diagnostic method according to the present invention comprises: 1. An ultrasound diagnostic method for an ultrasound diagnostic apparatus that transmits ultrasound into a subject, receives the ultrasound reflected by a target tissue in the subject to obtain a received signal, and outputs an ultrasound image of the target tissue based on the received signal, comprising: an acquiring step of acquiring a plurality of frames of ultrasound images when the angle of the ultrasound probe is changed by tilting the ultrasound probe; an extraction step of extracting a reference frame including an ultrasound image when the ultrasound probe and the target tissue are perpendicular to each other from the plurality of acquired frames; an output step of outputting the extracted reference frame; It has.

[0011] The program according to the present invention comprises: A computer of an ultrasound diagnostic device that is capable of transmitting ultrasound waves into a subject, receiving the ultrasound waves reflected by a target tissue in the subject to obtain a received signal, and outputting an ultrasound image of the target tissue based on the received signal, an acquisition unit that acquires a plurality of frames of ultrasound images when the angle of the ultrasound probe is changed by tilting the ultrasound probe; a setting unit that assigns angle information of the ultrasonic probe with respect to the skin surface of the subject during tilting operation to each of the plurality of frames; Function as.

[0012] The ultrasonic diagnostic method according to the present invention comprises: 1. An ultrasound diagnostic method capable of transmitting ultrasound into a subject, receiving the ultrasound reflected by a target tissue in the subject to obtain a received signal, and outputting an ultrasound image of the target tissue based on the received signal, comprising: an acquiring step of acquiring a plurality of frames of ultrasound images when the angle of the ultrasound probe is changed by tilting the ultrasound probe; a setting step of allocating angle information of the ultrasonic probe with respect to the skin surface of the subject during tilting operation to each of the plurality of frames; It has. [Effects of the Invention]

[0013] According to the present invention, a frame in which the ultrasonic probe and the target tissue are perpendicular to each other is extracted from a plurality of frames, so that an optimal ultrasonic image can be acquired even when the ultrasonic probe is tilted. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a block diagram of an ultrasonic diagnostic apparatus according to a first embodiment. [Figure 2] 5 is a flowchart showing an example of the operation of the ultrasound diagnostic apparatus when an ultrasound examination is performed by tilting the ultrasound probe according to the first embodiment. [Figure 3A] 3 is a diagram showing a state of the ultrasonic probe according to the first embodiment when the ultrasonic probe is tilted at −θ degrees. FIG. [Figure 3B] 3B is a diagram showing an ultrasound image of a frame acquired by the ultrasound probe shown in FIG. 3A. FIG. [Figure 4A] FIG. 2 is a diagram showing a state of the ultrasonic probe 150 according to the first embodiment when the ultrasonic probe is tilted at +θ degrees. [Figure 4B] 4B is a diagram showing an ultrasound image of a frame acquired by the ultrasound probe shown in FIG. 4A; FIG. [Figure 5] 10 is a graph showing changes in average luminance of an image region in n frames according to the first embodiment. [Figure 6] 3A and 3B are diagrams showing ultrasound images of frames acquired when the ultrasound probe according to the first embodiment is tilted at −θ degrees. [Figure 7] 3A and 3B are diagrams showing ultrasound images of frames acquired when the ultrasound probe according to the first embodiment is tilted at +θdeg. [Figure 8] 10 is a graph showing changes in average luminance in a plurality of image regions in each frame according to the first embodiment. [Figure 9] FIG. 2 is a diagram showing an example of an ultrasound image obtained by combining image information cut out from an image area of ​​another frame with an image area of ​​a base frame according to the first embodiment. [Figure 10A] 10 is an explanatory diagram illustrating a case where the angle of the ultrasonic probe relative to the skin surface is estimated using a first side surface of the housing of the ultrasonic probe according to the second embodiment. FIG. [Figure 10B] 10 is an explanatory diagram illustrating a case where the angle of the ultrasonic probe relative to the skin surface is estimated using the second side surface of the housing of the ultrasonic probe according to the second embodiment. FIG. [Figure 11A] FIG. 10 is an explanatory diagram for estimating the angle of the ultrasound probe relative to the skin surface using guide lines marked on the front surface of the ultrasound probe according to the second embodiment. [Figure 11B] FIG. 10 is an explanatory diagram for estimating the angle of the ultrasound probe relative to the skin surface using guide lines marked on the front surface of the ultrasound probe according to the second embodiment. [Figure 12] 10 is a flowchart showing an example of the operation of the ultrasound diagnostic apparatus when angle information and color tone information are assigned to each frame acquired by tilting the ultrasound probe according to the second embodiment. [Figure 13] 10 is an explanatory diagram illustrating a case where a specified angle value according to the second embodiment is equally divided by the number of frames n, and angle information and color tone information are assigned to each frame. FIG. [Figure 14]10 is a flowchart showing an example of the operation of the ultrasound diagnostic apparatus when an ultrasound examination is performed by tilting the ultrasound probe according to the second embodiment. [Figure 15] 10 is a flowchart showing an example of the operation of the ultrasound diagnostic apparatus when an ultrasound examination is performed by tilting the ultrasound probe according to the second embodiment. [Figure 16] FIG. 11 is a diagram showing an example of an examination screen on which angle information allocated to an extracted frame according to the second embodiment is displayed. [Figure 17] 10A and 10B are diagrams showing an example of an ultrasound image in the case where an image region within a frame has been subjected to color tone conversion according to the second embodiment. [Figure 18] FIG. 11 is a diagram showing an example of an examination screen on which angle information and the like allocated to a frame according to the second embodiment is displayed. [Figure 19] 10 is a flowchart showing an example of the operation of the ultrasound diagnostic apparatus when performing an ultrasound examination by tilting the ultrasound probe according to the third embodiment. [Figure 20] 10 is a flowchart showing an example of the operation of the ultrasound diagnostic apparatus when performing an ultrasound examination by tilting the ultrasound probe according to the third embodiment. [Figure 21] FIG. 11 is an explanatory diagram for extracting a lumen region that satisfies a threshold condition from an ultrasound image of a predetermined frame according to the third embodiment. [Figure 22] 10 is a graph showing a tracking result when a lumen region extracted from n / 2 frames is tracked between frames according to the third embodiment. [Figure 23] FIG. 11 is a diagram showing an example of an examination screen on which angle information allocated to an extracted frame according to the third embodiment is displayed. DETAILED DESCRIPTION OF THE INVENTION

[0015] An ultrasound diagnostic apparatus, a program, and an ultrasound diagnostic method according to preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0016] First Embodiment [Block diagram example of ultrasound diagnostic device 1] FIG. 1 is a block diagram of an ultrasound diagnostic device 1 according to the first embodiment. The ultrasound diagnostic device 1 is used by users such as doctors and technicians in medical facilities, patients' homes, etc. As shown in FIG. 1, the ultrasound diagnostic device 1 includes a device main body 100 and an ultrasound probe 150 connected to the device main body 100. The device main body 100 is provided with an operation unit 102 and a display unit 120. The device main body 100 also includes a transmission unit 104, a reception unit 106, an image generation unit 108, an image processing unit 110, a display control unit 112, a control unit 130, a storage unit 140, and a communication unit 160.

[0017] The operation unit 102 has, for example, an operation panel including a plurality of buttons and a trackball, and a touch panel combined with the display unit 120. The operation unit 102 receives input instructions from the user through various operations, converts the received input instructions into electrical signals, and outputs the electrical signals to the control unit 130.

[0018] The transmitting unit 104 supplies a drive signal, which is an electrical signal, to the ultrasonic probe 150 under the control of the control unit 130. The transmitting unit 104 includes, for example, a clock generating circuit, a delay circuit, and a pulse generating circuit. The clock generating circuit generates a clock signal that determines the transmission timing and transmission frequency of the drive signal. The delay circuit sets a delay time for each path provided in each probe 153 (described later) and delays the transmission of the drive signal by the set delay time. The delay circuit focuses a transmission beam formed by ultrasonic waves. The pulse generating circuit generates a pulse signal as a drive signal at a predetermined period. The transmitting unit 104 generates ultrasonic waves, for example, by driving consecutive parts of the multiple probes 153. The transmitting unit 104 scans by shifting the driven probe 153 in the azimuth direction each time an ultrasonic wave is generated.

[0019] The receiving unit 106 receives a received signal, which is an electrical signal, from the ultrasound probe 150 under the control of the control unit 130. The receiving unit 106 has, for example, an amplifier, an A / D conversion circuit, and a phasing and summing circuit. The amplifier amplifies the received signal at a preset amplification factor for each path provided in each probe 153. The A / D conversion circuit performs analog / digital conversion on the amplified received signal. The phasing and summing circuit adjusts the time phase by providing a delay time to the A / D converted received signal for each path provided in each probe 153, and then adds them together. The phasing and summing circuit generates sound ray data (sound ray signal) by phasing and summing. The receiving unit 106 may also have an amplifier for amplifying the received signal.

[0020] The image generating unit 108 performs envelope detection processing, logarithmic compression, etc. on the sound ray data supplied from the receiving unit 106. The image generating unit 108 further adjusts at least one of the dynamic range and gain of the sound ray data to convert the brightness, thereby generating B-mode image data. The B-mode image data represents the strength of the received signal by brightness, and is tomographic image information regarding the tissue within the subject. The image generating unit 108 is not limited to B-mode image data in B-mode. Other scan modes (image modes) include, for example, A-mode, M-mode, and scan modes using the Doppler method. Examples of the Doppler method include, for example, color Doppler mode and PWD. B-mode is an abbreviation for brightness mode. A-mode is an abbreviation for amplitude mode. M-mode is an abbreviation for motion mode. PWD is an abbreviation for pulsed wave Doppler.

[0021] The image processing unit 110 performs image processing on the B-mode image data output from the image generation unit 108. The image processing unit 110 performs image processing on the B-mode image data in accordance with various image parameters that are being set. The image processing unit 110 has an image memory unit 111 configured with a semiconductor memory such as a DRAM. DRAM is an abbreviation for Dynamic Random Access Memory. The image processing unit 110 stores the B-mode image data that has been subjected to image processing in the image memory unit 111 on a frame-by-frame basis under the control of the control unit 130. The image processing unit 110 outputs the image data generated as described above to the display control unit 112 in sequence under the control of the control unit 130.

[0022] The display control unit 112 generates an image signal for display by performing coordinate transformation and the like on the received image data under the control of the control unit 130. The display control unit 112 outputs the generated image signal for display to the display unit 120.

[0023] The display unit 120 is, for example, a display device such as a liquid crystal display or an organic EL display. EL is an abbreviation for Electro Luminescence. The display unit 120 displays an ultrasound image of the subject's tissue, organs, etc. on a screen based on an image signal for display output from the display control unit 112 under the control of the control unit 130. The ultrasound image may be a still image or a moving image.

[0024] The control unit 130 includes a processor such as a CPU and a memory such as a RAM. CPU is an abbreviation for Central Processing Unit. RAM is an abbreviation for Random Access Memory. The CPU reads out various programs 141 stored in the storage unit 140, expands them in the RAM, and executes various processes related to ultrasound examinations in cooperation with the programs 141. The CPU may be configured with a single processor or multiple processors.

[0025] In this embodiment, the control unit 130, which is a computer included in the ultrasound diagnostic apparatus 1, functions as at least an acquisition unit, an extraction unit, and an output unit. A processor, such as a CPU, of the control unit 130 executes a program 141 stored in a storage unit 140 or the like, thereby realizing various functions such as the acquisition unit, extraction unit, and output unit. The acquisition unit acquires multiple frames of ultrasound images when the ultrasound probe 150 is moved within a predetermined angle range by tilting the ultrasound probe 150. The tilting operation refers to rotating or tilting the ultrasound probe 150 within a predetermined angle range while the ultrasound probe 150 is pressed against the skin surface of the subject. The extraction unit extracts a frame (reference frame) including an ultrasound image when the ultrasound probe 150 and the target tissue are orthogonal to each other from the multiple frames acquired by the acquisition unit. The target tissue includes fibrous tissue such as muscles, tendons, and nerve bundles. Orthogonal means that when the fibrous tissue, which is the target tissue, is observed in the short axis direction, the central axis of the slice beam of the ultrasound probe 150 is orthogonal or approximately orthogonal to the fibrous tissue. The minor axis direction is the direction perpendicular to the longitudinal axis direction, where the direction of extension of fibrous tissue is the major axis direction. Furthermore, target tissues include not only muscle, tendon, and nerve bundles, which are collections of fibrous tissue, but also luminal tissue such as blood vessels. The interior of the lumen of a luminal structure is tissue such as blood, which is visualized as anechoic or hypoechoic, and is not anisotropically reflective tissue. However, wall tissue such as blood vessel walls exhibits anisotropic reflection characteristics, though not as much as muscle, and similar to muscle, good visualization is obtained when the orientation is perpendicular. The output unit outputs ultrasound image data of the frame extracted by the extraction unit to the display unit 120.

[0026] The storage unit 140 includes at least one storage module selected from, for example, an HDD, an SSD, a ROM, and a RAM. HDD is an abbreviation for Hard Disk Drive. SSD is an abbreviation for Solid State Drive. ROM is an abbreviation for Read Only Memory. RAM is an abbreviation for Random Access Memory. The storage unit 140 stores system programs, application programs, various data received by the communication unit 160, and the like. For example, the storage unit 140 stores a program 141 for executing processes related to ultrasound examinations, output processes for ultrasound image data, and the like.

[0027] The communication unit 160 includes, for example, a NIC, a LAN adapter, or a communication module including a receiver and a transmitter. NIC is an abbreviation for Network Interface Card. The communication unit 160 communicates various data, information, and the like with external devices such as a medical image management system via a network.

[0028] The ultrasonic probe 150 includes a head unit 152, a cable 154, and a connector 156. The head unit 152 is a part that is pressed against the surface of the subject's body. The head unit 152 is provided with a plurality of probes 153 made of piezoelectric elements. The probes 153 transmit ultrasonic waves to the subject based on a drive signal transmitted from the device main body 100, and receive reflected waves reflected by target tissue within the subject. The probes 153 may be arranged, for example, in a one-dimensional array in the scanning direction, or in a two-dimensional array (matrix). The number of probes 153 can be set arbitrarily. The scanning method of the ultrasonic probe 150 may be a linear scanning method, a convex scanning method, a sector scanning method, or the like.

[0029] One end of the cable 154 is electrically connected to the head unit 152, and the other end is electrically connected to a connector 156. The connector 156 is connected to the device main body 100. Note that communication between the device main body 100 and the ultrasonic probe 150 is not limited to wired communication using the cable 154. The communication method between the device main body 100 and the ultrasonic probe 150 may be wireless communication using UWB or the like. UWB is an abbreviation for Ultra Wide Band.

[0030] [Example of operation of ultrasound diagnostic device 1] 2 is a flowchart showing an example of the operation of the ultrasound diagnostic device 1 when performing an ultrasound examination by tilting the ultrasound probe 150 according to the first embodiment. The control unit 130 executes the program 141 in the storage unit 140, etc., to realize each process such as the acquisition step, extraction step, and output step shown below.

[0031] The user presses the ultrasonic probe 150 against the skin surface of the subject and transmits ultrasonic waves to the target tissue while tilting the ultrasonic probe 150. The receiving unit 106 sequentially receives reflected signals reflected from the target tissue when the angle of the ultrasonic probe 150 is changed by tilting the ultrasonic probe 150. The control unit 130 continuously acquires n frames of ultrasonic images based on the reflected signals received by the receiving unit 106 (step S100), where n is a positive integer.

[0032] The control unit 130 extracts image regions within each of the acquired n frames of ultrasound images where the inter-frame brightness correlation value is equal to or less than a threshold value CV (step S102). The brightness correlation value is a value indicating the brightness change between image regions located at the same or approximately the same position in each of the n frames of ultrasound images acquired by tilting. The threshold value CV is a threshold for extracting image regions with a low brightness correlation value between image regions located at the same or approximately the same position in each of the n frames of ultrasound images. Here, the following methods can be used to identify image regions from the entire image. For example, the image can be divided into m × n regions (m and n are any integers), and the brightness correlation value for each region is calculated to extract regions below the threshold value. The largest number of divisions is achieved when calculations are performed on a pixel-by-pixel basis, which requires a large amount of calculation. Therefore, an appropriate number of divisions is set taking into account the object of observation and the computing power of the device. Furthermore, the shape of the divided image regions does not have to be rectangular, and each divided image region may partially overlap with adjacent divided image regions. For example, a divided image region is set to a circular shape, and an adjacent divided image region is set by shifting the position so that they partially overlap. This method makes it possible to cover the entire image region even if the divided image region is circular. The threshold value may be a predetermined fixed value, but it is preferable to use a method in which it is adaptively set based on the obtained luminance correlation value. The threshold value is set, for example, to "extract the bottom 20% of the luminance correlation value."

[0033] FIG. 3A is a diagram showing the state of the ultrasonic probe 150 according to the first embodiment when tilted at -θ°. FIG. 3B is a diagram showing an ultrasonic image of frame F1 acquired by the ultrasonic probe 150 shown in FIG. 3A. FIG. 4A is a diagram showing the state of the ultrasonic probe 150 according to the first embodiment when tilted at +θ°. FIG. 4B is a diagram showing an ultrasonic image of frame F2 acquired by the ultrasonic probe 150 shown in FIG. 4A. Note that the ultrasonic image includes the flexor tendon of the middle finger, etc. FIG. 5 is a graph showing changes in the average brightness of the image region in n frames according to the first embodiment. In FIG. 5, the horizontal axis represents the frame number, and the vertical axis represents the average brightness of the image region.

[0034] In the ultrasound images of frames F1 and F2, for example, a region including the flexor tendon of the middle finger is designated image region A. In image region A of frame F2, the ultrasound from the ultrasound probe 150 is not perpendicular to the short axis direction of the tendon (fibrous tissue), and the ultrasound from the ultrasound probe 150 is anisotropically reflected. Therefore, image region A of frame F2 has lower brightness than image region A of frame F1 and image region A of frame F2. As a result, the difference in brightness between image region A in frames F1 and F2 is large, and the brightness correlation value decreases accordingly. The brightness correlation value between image region A in frames F1 and F2 is equal to or less than threshold value CV. In this case, control unit 130 extracts image region A as the image region in frames F1 and F2 where the brightness correlation value is equal to or less than threshold value CV.

[0035] The control unit 130 extracts image areas where the number of pixels in the extracted image areas from each of the n frames of ultrasound images is equal to or greater than a preset value TP (step S104). The set value TP is a threshold for extracting areas that have a cohesive structure, rather than pixel units that are affected by noise, etc. Therefore, the control unit 130 removes image areas with a small number of pixels from the extracted image areas.

[0036] The control unit 130 determines whether or not an image region has been extracted from each of the ultrasound images of n frames (step S106). That is, the control unit 130 determines whether or not there is an image region in the n frames whose brightness correlation value is equal to or less than the threshold value CV.

[0037] If the control unit 130 determines that an image region has been extracted from each of the ultrasound images of n frames, the process proceeds to step S108. The control unit 130 determines whether the number of image regions extracted from each of the n frames is one (single) or multiple (step S108). If the control unit 130 determines that the number of image regions extracted from each of the ultrasound images of n frames is one, the process proceeds to step S124.

[0038] The control unit 130 extracts a frame including an image region with the highest average brightness among the image regions extracted from each of the ultrasound images of the n frames (step S124). For example, as shown in Figures 3B and 5, if image region A of frame F1 has the highest average brightness, the control unit 130 extracts frame F1 including image region A with the highest average brightness from the n frames. After extracting a frame including an image region with a high average brightness, the control unit 130 proceeds to step S120.

[0039] The control unit 130 displays the ultrasound image of the frame having the highest average brightness of the entire region among the extracted n frames on the screen of the display unit 120 (step S120). Specifically, the control unit 130 outputs the ultrasound image data of frame F1 shown in FIG. 3B to the display unit 120, and displays the ultrasound image of frame F1 on the examination screen of the display unit 120.

[0040] On the other hand, if the control unit 130 determines that multiple image regions have been extracted from each ultrasound image of the n frames, the process proceeds to step S110. The control unit 130 extracts the image region with the largest number of pixels from the extracted multiple image regions. Next, the control unit 130 extracts from the n frames the frame including the image region with the highest average brightness from the extracted multiple image regions (step S110).

[0041] FIG. 6 is a diagram showing an ultrasound image of frame F3 acquired when the ultrasound probe 150 according to the first embodiment is tilted at -θ°. FIG. 7 is a diagram showing an ultrasound image of frame F4 acquired when the ultrasound probe 150 according to the first embodiment is tilted at +θ°. FIG. 8 is a graph showing changes in average brightness in image regions A1 and A2 of each frame according to the first embodiment. In FIG. 8, the horizontal axis represents the number of frames, and the vertical axis represents the average brightness of the image region. Note that, although an example using two frames will be described in the first embodiment for convenience, it is assumed that a large number of frames are actually included.

[0042] Each of frames F3 and F4 includes multiple image areas Am. For example, the first image area Am is the flexor tendon of the middle finger, and the second image area Am is the tendon of the flexor tendon of the index finger. In this embodiment, an identification number is assigned to each image area Am according to the number of pixels (area). Specifically, if the image area Am includes an image area of ​​the flexor tendon of the middle finger and an image area of ​​the flexor tendon of the index finger, as shown in FIGS. 6 and 7, the image area of ​​the flexor tendon of the middle finger is larger than the image area of ​​the flexor tendon of the index finger. Therefore, in frames F3 and F4, the control unit 130 assigns m=1 to the image area Am of the flexor tendon of the middle finger and m=2 to the image area Am of the flexor tendon of the index finger.

[0043] First, the control unit 130 performs processing on a frame including image region A1 where m=1. The control unit 130 extracts the frame with the highest average luminance of image region A1 from frames F3 and F4. As shown in FIGS. 6, 7, and 8, the average luminance of image region A1 in frame F3 is higher than the average luminance of image region A1 in frame F4. Therefore, the control unit 130 extracts frame F3 as a base frame from frames F4 and F2. The base frame is a frame displayed on the inspection screen of the display unit 120. While the base frame was selected and extracted using average luminance here, it may also be selected and extracted using an image luminance histogram and features such as skewness, which indicates deviation of symmetry from a normal distribution of the luminance histogram, or kurtosis, which indicates sharpness (the peaks and width of the tails of the distribution) relative to the normal distribution. Skewness is calculated using the following formula (1). Kurtosis is calculated using the following formula (2).

[0044]

number

[0045]

number

[0046] Next, when the process for image region A1 where m=1 is completed, control unit 130 increments variable m and sets m=2 (step S112).

[0047] The control unit 130 extracts the frame with the highest average brightness of the m-th largest image area Am from the image areas extracted from each of the n ultrasound images of the frames. Next, the control unit 130 cuts out image information IFm from the image area Am of the extracted frame (step S114). Below, since m=2 is set in step S112, processing related to the frame including the image area A2 will be described.

[0048] Specifically, the control unit 130 extracts the frame with the highest average brightness from the image region A2 of each of frames F3 and F4. As shown in FIGS. 6, 7, and 8, the average brightness of the image region A2 of frame F4 is higher than the average brightness of the image region A2 of frame F3. Therefore, the control unit 130 extracts frame F4 from frames F3 and F4. Next, as shown in FIG. 7, the control unit 130 extracts image information IF2 from the image region A2 of the extracted frame F4. The image information is extracted based on the position information of the image region A2 and stores the brightness information together with the position information in a system memory or the like. In this case, the region position information of the image region A2 may be used as is, but if the target tissue is a tendon, the edges of the low-brightness and high-brightness areas in the image region A2 may be detected and the edge may be used as the boundary for extraction. In this case, the image information IF2 includes the flexor tendon of the index finger.

[0049] The control unit 130 combines the image information IFm clipped from another frame with the m-th largest image area Am in the ultrasound image of the base frame (step S116). This combination is performed by replacing (overwriting) the brightness information at the corresponding position based on the brightness information and position information of the image information IFm temporarily stored in system memory, etc. At this time, to make the boundary between the base frame and the image area less noticeable, a boundary blurring process may be performed to set the average brightness of the base frame and the image information IFm at the pixel corresponding to the boundary. FIG. 9 is a diagram showing an example of an ultrasound image obtained by combining image information IF2 clipped from the image area A2 of frame F4 with image area A2 of frame F3 according to the first embodiment. As shown in FIG. 9, the control unit 130 pastes the image information IF2 clipped from the image area A2 of frame F4 into image area A2 of frame F3, which is the base frame. This allows the image area A2 to be expressed with high brightness in the ultrasound image of frame F3.

[0050] The control unit 130 determines whether m=s (step S118). s is, for example, the number of image areas drawn in one frame. If m=s, the control unit 130 proceeds to step S120. On the other hand, if the control unit 130 determines that m=s does not hold, the control unit 130 proceeds to step S122. The control unit 130 increments m (m=m+1) and returns to step S114.

[0051] The control unit 130 causes the display unit 120 to display the ultrasound image of the frame used as the base frame (step S120). Specifically, as shown in FIG. 9, the control unit 130 outputs the ultrasound image data of frame F3 to the display unit 120 and causes the display unit 120 to display the ultrasound image of frame F3 on the examination screen. The ultrasound image of frame F3 includes an image region A1 including the flexor tendon of the middle finger and an image region A2 including the flexor tendon of the index finger. Image region A2 is image information IF2 cut out from image region A2 of frame F4, which is different from frame F3. Image region A1 and image region A2 are each displayed at high brightness.

[0052] Returning to step S106, if the control unit 130 determines that an image region has not been extracted from the nth frame of ultrasound images, the process proceeds to step S126. That is, the brightness change between image regions in the nth frame is small, and the brightness correlation value is high. In this case, all of the acquired nth frame of ultrasound images have a brightness above a certain level, and are proper ultrasound images.

[0053] The control unit 130 extracts the frame with the highest average brightness of the entire region from the n frames (step S126). Specifically, the control unit 130 calculates the average brightness of all pixels in each frame, and extracts the frame with the highest average brightness from among them. After extracting the frame with the highest average brightness, the control unit 130 proceeds to step S120.

[0054] The control unit 130 causes the display unit 120 to display the ultrasound image of the frame having the highest average brightness of the entire region among the extracted n frames (step S120).

[0055] According to the first embodiment, the following advantageous effects can be achieved. When observing fibrous tissue such as muscles, tendons, and nerve bundles in the short axis direction by tilting, if the ultrasonic probe 150 is not perpendicular to the fibrous tissue, anisotropic reflection at the fibrous tissue may prevent proper reception of the reflected signal. Therefore, accurate tilting operation is required to orient the ultrasonic probe 150 perpendicular to the fibrous tissue. However, an operator with low proficiency has difficulty accurately orienting the ultrasonic probe 150 perpendicular to the fibrous tissue during tilting operation.

[0056] According to the first embodiment, when the correlation brightness value between image regions containing fibrous tissues in multiple frames is low, the control unit 130 can extract a frame containing an image region with the highest average brightness from the multiple frames. In other words, by performing a tilting operation, a frame in which the ultrasound probe 150 and the image region are most perpendicular can be automatically generated. This allows an optimal ultrasound image to be acquired while performing a tilting operation of the ultrasound probe 150 without using any additional equipment. As a result, an optimal ultrasound image can be acquired with a simple operation without performing any special operations, and since additional equipment is not required, an increase in costs can be prevented. Furthermore, the operator can acquire an optimal ultrasound image without being aware of the anisotropic reflection of fibrous tissues by simply performing a tilting operation of the ultrasound probe 150.

[0057] Furthermore, if each frame contains an image region containing multiple fibrous tissues, the optimal angle relative to the ultrasound probe 150 may differ for each of the multiple image regions. In this case, the frame containing the optimal image region differs for each of the multiple image regions. This has led to a problem in that multiple image regions cannot be simultaneously observed and compared in one frame of ultrasound image displayed on the examination screen.

[0058] In contrast, according to the first embodiment, when each frame includes at least a first image region and a second image region, the following processing is performed. The control unit 130 extracts a frame including the first image region with the highest average brightness from among the first image regions as a base frame. Next, the control unit 130 extracts a frame including the second image region with the highest average brightness from among the second image regions, and extracts image information from within the second image region of that frame. Next, the control unit 130 combines the extracted image information with the second image region of the base frame. As a result, in one frame of ultrasound image, which is the base frame, it is possible to display not only the high-brightness first image region but also the combined high-brightness second image region. As a result, multiple image regions displayed at high brightness can be simultaneously observed and compared on a single examination screen.

[0059] Second Embodiment In the second embodiment, angle information of the ultrasonic probe 150 at the time of acquisition of each frame is assigned to each frame acquired by tilting the ultrasonic probe 150. The following description will focus on differences from the first embodiment, and components that are substantially the same as those in the first embodiment will be given the same reference numerals, and common descriptions will be omitted or simplified.

[0060] [Regarding the specified angle when tilting the ultrasonic probe 150] A specified angle value is set in the ultrasonic probe 150 to specify and estimate the angle at which the ultrasonic probe 150 can be tilted relative to the skin surface S during tilting operation. The specified angle value is specified by using the housing shape of the ultrasonic probe 150 and guide information written on the housing of the ultrasonic probe 150. In this embodiment, the means for specifying the angle of the ultrasonic probe 150 by using the housing shape of the ultrasonic probe 150 is called a first angle estimation means. The means for specifying the angle of the ultrasonic probe 150 by using the guide information written on the ultrasonic probe 150 is called a second angle estimation means.

[0061] First, the first angle estimation means will be described. Fig. 10A is an explanatory diagram of a case where the angle of the ultrasonic probe 150 with respect to the skin surface S is estimated using the first side surface 151a of the housing 151 of the ultrasonic probe 150. Fig. 10B is an explanatory diagram of a case where the angle of the ultrasonic probe 150 with respect to the skin surface S is estimated using the second side surface 151b of the housing 151 of the ultrasonic probe 150. The housing 151 of the ultrasonic probe 150 is provided with a first side surface 151a and a second side surface 151b on the opposite side. The first side surface 151a and the second side surface 151b of the housing 151 are configured as inclined surfaces that are inclined at a predetermined angle with respect to the central axis AC of the ultrasonic probe 150. In the ultrasonic probe 150, an axis passing through the first side surface 151a of the ultrasonic probe 150 is defined as a reference axis AR, and an axis passing through the second side surface 151b of the ultrasonic probe 150 is defined as a reference axis AL.

[0062] As shown in FIG. 10A, when the first side surface 151a is perpendicular to the skin surface S, the angle between the central axis AC of the ultrasonic probe 150 and the reference axis AR is −θ°. As shown in FIG. 10B, when the second side surface 151b is perpendicular to the skin surface S, the angle between the central axis AC of the ultrasonic probe 150 and the reference axis AL is +θ°. Here, since the ultrasonic probe 150 has a bilaterally symmetrical shape when viewed from the front, −θ and +θ are within the same angle range. The user can operate the ultrasonic probe 150 within a range of specified angle values ​​by tilting the ultrasonic probe 150 so that the first side surface 151a and the second side surface 151b of the ultrasonic probe 150 are perpendicular to the skin surface S.

[0063] Next, the second angle estimation means will be described. Fig. 11A is an explanatory diagram of a case where a guide line La marked on the front surface 151c of the ultrasonic probe 150 is used to estimate the angle of the ultrasonic probe 150 with respect to the skin surface S. Fig. 11B is an explanatory diagram of a case where a guide line Lb marked on the front surface 151c of the ultrasonic probe 150 is used to estimate the angle of the ultrasonic probe 150 with respect to the skin surface S. As guide information for the second angle estimation means, for example, two guide lines La and Lb marked on the front surface 151c of the ultrasonic probe 150 can be used.

[0064] V-shaped guide lines La and Lb are marked on the front surface 151c of the ultrasonic probe 150. The guide lines La and Lb are arranged symmetrically with respect to the central axis AC of the ultrasonic probe 150. The acute angle of the V is located at the center of the tip of the ultrasonic probe 150. In this embodiment, the angle formed by the guide lines La and Lb is a specified angle value. Specifically, when the guide line La is perpendicular to the skin surface S, the angle formed by the central axis AC of the ultrasonic probe 150 and the guide line La is −θ°. When the guide line Lb is perpendicular to the skin surface S, the angle formed by the central axis AC of the ultrasonic probe 150 and the guide line Lb is +θ°. Because the guide lines La and Lb are symmetrical with respect to the central axis AC of the ultrasonic probe 150, −θ and +θ are in the same angle range. The user can operate the ultrasonic probe 150 within a range of specified angle values ​​by tilting the ultrasonic probe 150 so that the guide lines La and Lb of the ultrasonic probe 150 are perpendicular to the skin surface S.

[0065] [Example of operation of ultrasound diagnostic device 1 when angle information and color tone information are assigned to each frame] 12 is a flowchart showing an example of the operation of the ultrasound diagnostic device 1 when assigning angle information and color tone information to each frame acquired by tilting the ultrasound probe 150 according to the second embodiment. The control unit 130 executes the program 141 in the storage unit 140, etc., to realize each process such as the acquisition step and setting step shown below.

[0066] The control unit 130 acquires n frames of ultrasound images when the ultrasound probe 150 is changed within a specified angle range with respect to the skin surface S by tilting operation (step S200). The means for supporting the operation of tilting the ultrasound probe 150 to the specified angle value may use the above-mentioned first angle estimation means or the second angle estimation means.

[0067] For example, when using the first angle estimation means, the user tilts the ultrasonic probe 150 with respect to the skin surface S so that the first side surface 151a of the ultrasonic probe 150 is perpendicular to the skin surface S, as shown in FIG. 10A. This allows the ultrasonic probe 150 to be tilted by a specified angle value of −θdeg with respect to the skin surface S. From this position, the user tilts the ultrasonic probe 150 in the opposite direction to the skin surface S, as shown in FIG. 10B, so that the second side surface 151b of the ultrasonic probe 150 is perpendicular to the skin surface S. This allows the ultrasonic probe 150 to be tilted by a specified angle value of +θdeg with respect to the skin surface S. In this way, the ultrasonic probe 150 can be tilted within a preset angle range.

[0068] The control unit 130 determines whether the simple angle display mode is set to ON (step S202). The simple angle display mode is a mode in which, when an ultrasound image of a predetermined frame is displayed on the display unit 120, angle information of the ultrasound probe 150 at the time the predetermined frame was acquired is additionally displayed. The simple angle display mode may be set to ON or OFF as appropriate by operating an icon, button, or the like displayed on the examination screen, etc. If the control unit 130 determines that the simple angle display mode is set to ON, the control unit 130 proceeds to step S204. On the other hand, if the control unit 130 determines that the simple angle display mode is set to OFF, the control unit 130 ends the series of processes without performing any processing related to the simple angle display mode.

[0069] The control unit 130 equally divides the preset specified angle value by the number n of acquired frames and assigns angle information to each frame (step S204). The control unit 130 functions as a setting unit. FIG. 13 is an explanatory diagram of a case in which the specified angle value according to the second embodiment is equally divided by the number n of frames and angle information and color tone information are assigned to each frame. The following describes a case in which the specified angle value is 60° and the number of frames is 31. In this case, the user tilts the ultrasonic probe 150 within a range from −30° (−θ) to +30° (+θ) with respect to a line perpendicular to the skin surface S. The tilting speed is assumed to be constant. Through this tilting operation, the control unit 130 acquires 31 consecutive frames of ultrasonic images. Next, the control unit 130 equally divides the specified angle value by the number n of frames using the following equation (3) to calculate the movement angle per frame during the tilting operation of the ultrasonic probe 150. Movement angle per frame = θ (deg) × 2 / (n-1) (3) The control unit 130 substitutes the preset specified angle value of 60° and the number of acquired frames, 31, into the above formula (1). As a result, the control unit 130 obtains 2° as the angle of movement or change per frame.

[0070] Next, the control unit 130 assigns angle information to each frame based on the calculated movement angle per frame during tilt operation of the ultrasonic probe 150. For example, as shown in FIG. 13, the control unit 130 assigns angle information of −30° to the first frame and −16° to the eighth frame. The control unit 130 assigns angle information of 0° to the 16th frame, which is the middle frame of the consecutive images. The control unit 130 assigns angle information of 16° to the 24th frame and 30° to the 31st frame. In this way, the control unit 130 assigns unique angle information to all other frames as well.

[0071] The control unit 130 assigns color information corresponding to the angle information assigned to each frame to each frame (step S206). The color information is defined by a color bar C that changes continuously or stepwise, for example, from blue to blue-white to white to red-white to red, as shown in FIG. 13. In this embodiment, blues are indicated by hatching with dots, reds are indicated by hatching with diagonal lines, and white is indicated by a white pattern. The dots become larger from blue to blue-white, and the width of the diagonal lines becomes thinner from red to red-white. A unique color from the color bar C is assigned to each frame acquired by tilting. The control unit 130 may assign color information to each frame using a lookup table in which angle information and color information are associated. For example, as shown in FIG. 13, the control unit 130 assigns blue as color information to the first frame and blue-white as color information to the eighth frame. Similarly, the control unit 130 assigns white as the color tone information to the 16th frame, red-white as the color tone information to the 24th frame, and red as the color tone information to the 31st frame. In this manner, the control unit 130 assigns unique color tone information to the other frames as well. After the color tone information assignment is complete, the control unit 130 creates a lookup table in which frame numbers, angle information, and color tone information are associated with each other. The created lookup table can be stored in a memory such as the storage unit 140.

[0072] [Example of operation of ultrasound diagnostic device 1 during ultrasound examination] Next, a method for acquiring an ultrasound image when the above-described simple angle display mode is combined with the method for extracting frames including image areas with high average brightness from a plurality of frames described in the first embodiment will be described.

[0073] 14 and 15 are flowcharts showing an example of the operation of the ultrasound diagnostic device 1 when an ultrasound examination is performed by tilting the ultrasound probe 150 according to the second embodiment. The control unit 130 executes the program 141 in the storage unit 140, etc., to realize each process such as the acquisition step, extraction step, and output step shown below.

[0074] 14, the control unit 130 continuously acquires n frames of ultrasound images when the ultrasound probe 150 is moved within a specified angle range relative to the skin surface S by tilting (step S300). The control unit 130 extracts image regions from the image regions of the acquired n frames of ultrasound images where the luminance correlation value between frames is equal to or less than a threshold value CV (step S302). The control unit 130 extracts image regions from the n frames where the number of pixels in the extracted image regions is equal to or greater than a preset value TP (step S304).

[0075] The control unit 130 determines whether an image region has been extracted from each of the ultrasound images of the n frames (step S306). If the control unit 130 determines that an image region has been extracted from each of the ultrasound images of the n frames, the process proceeds to step S308. The control unit 130 determines whether one or more image regions have been extracted from each of the n frames (step S308).

[0076] If the control unit 130 determines that one image area has been extracted from each ultrasound image of n frames, the process proceeds to step S342. On the other hand, if the control unit 130 determines that multiple image areas have been extracted from each ultrasound image of n frames, the process proceeds to step S310.

[0077] First, a case where one image region is extracted from each of the ultrasound images of n frames will be described. The control unit 130 extracts a frame including an image region with the highest average brightness among the image regions extracted from each of the n frames (step S342). For example, as shown in FIG. 3B, if image region A of frame F1 has the highest average brightness, the control unit 130 extracts frame F1 including image region A with the highest average brightness from the n frames. After extracting the frame including image region A with the highest average brightness, the control unit 130 proceeds to step S344.

[0078] The control unit 130 determines whether the simple angle display mode is set to ON (step S344). If the control unit 130 determines that the simple angle display mode is set to ON, the process proceeds to step S346. On the other hand, if the control unit 130 determines that the simple angle display mode is set to OFF, the process proceeds to step S332.

[0079] The control unit 130 displays the angle information assigned to the frame extracted in step S342 in an information display area provided on the examination screen of the display unit 120 (step S346). FIG. 16 is a diagram showing an example of an examination screen 200 on which the angle information Ia assigned to the extracted frame F1 is displayed. An image display area 202 displaying an ultrasound image of frame F1 is provided approximately in the center of the examination screen 200. An information display area 204 displaying the angle information Ia of the ultrasound probe 150 when the frame F1 displayed in the image display area 202 was acquired is provided on the right side of the examination screen 200. The information display area 204 displays "deg -14°", which is the angle information Ia assigned to frame F1. Note that in FIG. 16, for convenience, an ultrasound image is displayed in the image display area 202, but in reality, no ultrasound image is displayed in the image display area 202 at this timing.

[0080] After displaying the angle information Ia on the examination screen 200, the control unit 130 proceeds to step S332. The control unit 130 causes the examination screen 200 of the display unit 120 to display an ultrasound image of a frame including an image region with the highest average brightness (step S332). Specifically, as shown in FIG. 16, the control unit 130 causes the image display region 202 of the examination screen 200 to display an ultrasound image of frame F1 including image region A with the highest average brightness. As a result, the examination screen 200 simultaneously displays the ultrasound image of frame F1 including image region A with the highest average brightness and the angle information Ia of the ultrasound probe 150 when the ultrasound image was acquired.

[0081] Next, a case where multiple image regions are extracted from n frames of ultrasound images will be described. The control unit 130 extracts the image region with the largest number of pixels from the multiple extracted image regions. Next, the control unit 130 extracts the frame with the highest average brightness for the extracted image region from the n frames (step S310). An example of a case where multiple image regions are present will be described based on the above-mentioned FIGS. 6 and 7. Specifically, when frames F3 and F4 each contain multiple image regions Am, the control unit 130 extracts image region A1 as the image region with the largest number of pixels. Next, the control unit 130 extracts frame F3 as the frame with the highest average brightness for image region A1.

[0082] The control unit 130 determines whether the simplified angle display mode is set to ON (step S312). If the control unit 130 determines that the simplified angle display mode is set to ON, the process proceeds to step S314. On the other hand, if the control unit 130 determines that the simplified angle display mode is set to OFF, the process proceeds to step S318.

[0083] The control unit 130 performs color conversion on the image region within the frame based on the color tone information assigned to the frame extracted in step S310 (step S314). First, the control unit 130 performs processing on the frame including the image region A1 where m=1. FIG. 17 is a diagram showing an example of an ultrasound image obtained when color tone conversion is performed on the image region A1, etc., within the frame F3 according to the second embodiment. Note that the frame F3 is the eighth of 31 frames. In this case, as shown in FIG. 13, "bluish-white" is assigned as the color tone information for the frame F3. The control unit 130 refers to the lookup table and acquires the "bluish-white" color tone information assigned to the eighth frame F3. Based on the acquired color tone information, the control unit 130 converts the image region A1 within the ultrasound image of the eighth frame F3 to the "bluish-white" color tone.

[0084] The control unit 130 converts the color tone of the angle information assigned to the frame and displays it in the information display area 204 of the examination screen 200 based on the color tone information assigned to the frame (step S316). If the extracted frame F3 is the eighth frame, "-16°" is assigned as the angle information Ib of frame F3, as shown in FIG. 13. FIG. 18 is a diagram showing an example of the examination screen 200 on which the angle information Ib assigned to frame F3 according to the second embodiment is displayed. The information display area 204 displays "-16°", which is the angle information Ib assigned to frame F3. The angle information Ib is displayed in "bluish-white", which is the color tone information assigned to frame F3. Note that although the angle information Ic, ultrasound image, etc. are displayed in FIG. 18 for convenience, the angle information Ic, etc. are not displayed at this stage.

[0085] As shown in FIG. 15, when the process for image region A1 where m=1 is completed, control unit 130 increments variable m and sets m=2 (step S318).

[0086] The control unit 130 extracts the frame with the highest average brightness of the m-th largest image region from the multiple image regions extracted from the n frames. Next, the control unit 130 cuts out image information IFm from the image region of the extracted frame (step S320). Below, since m=2 is set in step S318, processing related to the frame including image region A2 will be described.

[0087] Specifically, the control unit 130 extracts the frame with the highest average brightness from the image regions A2 of frames F3 and F4. As shown in FIGS. 6 and 7, the average brightness of the image region A2 of frame F4 is higher than the average brightness of the image region A2 of frame F3. Therefore, the control unit 130 extracts frame F4 from frames F3 and F4. Next, the control unit 130 cuts out image information IF2 from the image region A2 of the extracted frame F4.

[0088] The control unit 130 determines whether the simple angle display mode is set to ON (step S322). If the control unit 130 determines that the simple angle display mode is set to ON, the process proceeds to step S324. On the other hand, if the control unit 130 determines that the simple angle display mode is set to OFF, the process proceeds to step S328.

[0089] The control unit 130 performs color tone conversion on the image information IFm based on the color tone information allocated to the frame of the image information IFm extracted in step S320 (step S324). Note that the frame F4 extracted in step S320 is the 26th of the 31 frames. In this case, "red and white" is allocated as the color tone information of frame F4, as shown in FIG. 13. The control unit 130 references the lookup table and obtains the "red and white" color tone information allocated to the 26th frame F4. Based on the obtained color tone information, the control unit 130 converts the image information IF2 extracted from the 26th frame F4 to the "red and white" color tone.

[0090] The control unit 130 converts the color tone of the angle information assigned to the frame and displays it in the information display area 204 of the examination screen 200 based on the color tone information assigned to the frame (step S326). If the frame F4 extracted in step S320 is the 26th frame, "+20°" is assigned as the angle information Ic of frame F4, as shown in FIG. 13. In the information display area 204, "deg +20°", which is the angle information Ic assigned to frame F4, is displayed below the angle information Ib of frame F3. The angle information Ic is displayed in "red and white", which is the color tone information assigned to frame F4.

[0091] The control unit 130 combines the image information IFm cut out from another frame with the m-th largest image area in the frame used as the base frame (step S328). Specifically, as shown in Fig. 17, the control unit 130 pastes and combines image information IF2 cut out from image area A2 of frame F4 with image area A2 of frame F3, which is the base frame. This allows the image area A2 to be expressed with high brightness in addition to the image area A1 in the ultrasound image of frame F3.

[0092] The control unit 130 determines whether m=s (step S330). s is, for example, the number of image areas drawn in one frame. If the variable m is s, the control unit 130 proceeds to step S332. On the other hand, if the control unit 130 determines that m=s is not true, the control unit 130 proceeds to step S316. The control unit 130 increments m (m=m+1) and returns to step S318.

[0093] The control unit 130 displays the ultrasound image of the frame used as the base frame on the examination screen 200 of the display unit 120 (step S332). As shown in FIG. 18, the control unit 130 displays the ultrasound image of frame F3 used as the base frame on the examination screen 200 of the display unit 120. Image region A1 of the ultrasound image is displayed in "blue-white." Image information IF2 clipped from image region A2 of frame F4 is combined with image region A2 of the ultrasound image. The combined image information IF2 is displayed in "red-white." This allows the image region A1 and image region A2 to be displayed at high brightness on the examination screen 200 of the display unit 120. That is, images of the flexor tendons of the middle finger and the flexor tendons of the index finger can be drawn at high brightness on the examination screen 200 of the display unit 120.

[0094] 14, if the control unit 130 determines that an image area has not been extracted from the nth frame of ultrasound images, the process proceeds to step S336. That is, the brightness change between image areas in the nth frame is small, and the brightness correlation value is high. In this case, all of the acquired nth frame of ultrasound images have a brightness above a certain level, and are proper ultrasound images.

[0095] The control unit 130 extracts the frame with the highest average brightness of the entire region from among the n frames (step S336). After extracting the frame with the highest average brightness, the control unit 130 proceeds to step S338.

[0096] The control unit 130 determines whether the simple angle display mode is set to ON (step S338). If the control unit 130 determines that the simple angle display mode is set to ON, the process proceeds to step S340. On the other hand, if the control unit 130 determines that the simple angle display mode is set to OFF, the process proceeds to step S332.

[0097] The control unit 130 displays the angle information assigned to the frame extracted in step S336 in the information display area 204 of the examination screen 200 (step S340). After displaying the angle information, the control unit 130 proceeds to step S332. The control unit 130 displays the ultrasound image of the frame extracted in step S336 in the image display area 202 of the examination screen 200 (step S332). The examination screen 200 simultaneously displays the ultrasound image of the frame including the high-brightness image area and the angle information of the ultrasound probe 150 when the ultrasound image was acquired.

[0098] According to the second embodiment, it is possible to achieve the same effects as those of the first embodiment. Furthermore, according to the second embodiment, for a predetermined frame acquired by tilting, angle information of the ultrasonic probe 150 with respect to the skin surface S when the frame was acquired is displayed on the examination screen 200. Therefore, information regarding the depth direction of the ultrasonic probe 150 can be grasped relatively or semi-quantitatively on the two-dimensional examination screen 200. Furthermore, even when there are multiple image regions as the target tissue, the angle information of each image region is displayed on the examination screen 200, so the relative positional relationship between the image regions can also be grasped. As a result, the angle information of each image region can be used as new diagnostic information and can also be used as index information during rehabilitation.

[0099] Third Embodiment In the third embodiment, frames containing high-intensity lumen regions are extracted based on the depth of the lumen region in the ultrasound image. The following describes a method for acquiring ultrasound images in which the simplified angle display mode described in the second embodiment is combined with the method of extracting frames containing high-intensity lumen regions based on the depth of the lumen region in the ultrasound image of the third embodiment. Components that are substantially common to the first and second embodiments are denoted by the same reference numerals, and common descriptions will be omitted or simplified.

[0100] 19 and 20 are flowcharts showing an example of the operation of the ultrasound diagnostic apparatus 1 when performing an ultrasound examination by tilting the ultrasound probe 150 according to the third embodiment. The control unit 130 executes the program 141 in the storage unit 140, etc., to realize each process such as the acquisition step, extraction step, and output step shown below.

[0101] As shown in FIG. 19, the control unit 130 continuously acquires n frames of ultrasound images when the ultrasound probe 150 is moved within a specified angle range relative to the skin surface S by tilting (step S400).

[0102] The control unit 130 extracts a continuous luminal region with a brightness difference within a threshold value TB from the frame corresponding to the n / 2th frame (rounded up) of the n frames (step S402). Here, the frame with the elevation angle closest to 0° relative to the skin surface S is selected as the base frame. Unlike muscles, the interior of a luminal structure does not become hyperechoic even when perpendicular. Therefore, it is difficult to select a base frame based on average brightness. However, brightness histogram features such as skewness and kurtosis may be used. The threshold value TB is the maximum brightness difference that allows adjacent pixels to be considered similar regions, and is used to extract a luminal region from an ultrasound image. FIG. 21 is an explanatory diagram illustrating the extraction of a luminal region B that satisfies the threshold value TB from an ultrasound image of a predetermined frame according to the third embodiment. Specifically, when the number of acquired frames is 31, the control unit 130 extracts the 16th frame F5. The control unit 130 extracts a continuous luminal region B with a brightness difference below the threshold value TB from the ultrasound image of the extracted 16th frame. Furthermore, in order to selectively extract a luminal region whose interior changes from anechoic to hypoechoic, it is preferable to set an upper limit value for brightness in addition to the brightness difference.

[0103] The control unit 130 extracts regions where the number of pixels in the luminal region extracted from the n frames is equal to or greater than a set value TP and equal to or less than a tolerance value MP (step S404). The set value TP is a threshold for extracting regions that are cohesive as tissue, rather than pixel-by-pixel units that are affected by noise, etc. The tolerance value MP is the maximum number of pixels to be extracted as the luminal region, and is a threshold for eliminating deep, signal-free regions. The set value TP and tolerance value MP may be default values ​​that change in accordance with the display image size, or the user may be able to select any numerical value on a screen, etc.

[0104] The control unit 130 extracts luminal regions where the ratio of the number of pixels in the luminal region extracted from the n frames to the number of surrounding pixels is equal to or greater than a threshold value TC (step S406). The threshold value TC is a threshold for extracting luminal regions with high accuracy by excluding regions where the ratio of the number of surrounding pixels to the number of pixels in the image is high, such as linear or irregular shapes.

[0105] The control unit 130 determines whether or not a lumen region has been extracted from each of the n frames of ultrasound images (step S408). If the control unit 130 determines that a lumen region has been extracted from the n frames of ultrasound images, the process proceeds to step S410.

[0106] The control unit 130 determines whether one or more lumen regions have been extracted from each of the n frames (step S410). If the control unit 130 determines that one lumen region has been extracted from each of the n frames of ultrasound images, the process proceeds to step S438. On the other hand, if the control unit 130 determines that multiple lumen regions have been extracted from the n frames of ultrasound images, the process proceeds to step S412.

[0107] First, a case where one lumen region is extracted from each ultrasound image of n frames will be described. The control unit 130 tracks changes in the depth direction of the lumen region extracted from n / 2 frames for each frame. Next, the control unit 130 extracts the frame including the lumen region with the shallowest display depth from the lumen regions of each tracked frame (step S438). This utilizes the fact that, for example, when a tilt operation is performed with the contact point of the ultrasound probe 150 fixed on the skin surface S, the lumen region is closest when perpendicular to the lumen region and is displayed at the shallowest depth. FIG. 22 is a graph showing the tracking results when the lumen region B extracted from n / 2 frames according to the third embodiment is tracked between frames. In FIG. 22, the horizontal axis represents frames and the vertical axis represents display depth. Note that the display depth is based on the shallowest part of the lumen region in each frame. The control unit 130 refers to the graph and extracts frame F6 as the frame with the shallowest depth among the lumen regions B of the n frames.

[0108] The control unit 130 determines whether the simplified angle display mode is set to ON (step S440). If the control unit 130 determines that the simplified angle display mode is set to ON, the process proceeds to step S442. On the other hand, if the control unit 130 determines that the simplified angle display mode is set to OFF, the process proceeds to step S434.

[0109] The control unit 130 displays the angle information Id assigned to the frame extracted in step S438 in the information display area 204 of the examination screen 200 (step S442). FIG. 23 is a diagram showing an example of the examination screen 200 on which the angle information Id assigned to the extracted frame F6 according to the third embodiment is displayed. For example, the information display area 204 displays "deg +16°", which is the angle information Id assigned to frame F6. The angle information Id is the angle of the ultrasound probe 150 with respect to the skin surface S when frame F6 was acquired by tilting. Note that, for convenience, an ultrasound image is displayed in the image display area 202 in FIG. 23, but in reality, no ultrasound image is displayed in the image display area 202 at this timing.

[0110] The control unit 130 displays the ultrasound image of the frame extracted in step S438 in the image display area 202 of the examination screen 200 (step S434). Specifically, as shown in Fig. 23, the control unit 130 displays the ultrasound image of frame F6 including the luminal region B with the shallowest depth in the image display area 202 of the examination screen 200. As a result, the examination screen 200 simultaneously displays the ultrasound image of frame F6 including the luminal region B with the highest brightness, and the angle information Id of the ultrasound probe 150 when the ultrasound image was acquired.

[0111] Next, a case where multiple lumen regions are extracted from each ultrasound image of n frames will be described. The control unit 130 tracks the change in the depth direction of the largest lumen region among the lumen regions extracted from n / 2 frames in each frame. Next, the control unit 130 extracts the frame including the lumen region with the shallowest display depth from the tracked lumen regions of each frame (step S412).

[0112] The control unit 130 determines whether the simple angle display mode is set to ON (step S414). If the control unit 130 determines that the simple angle display mode is set to ON, the process proceeds to step S416. On the other hand, if the control unit 130 determines that the simple angle display mode is set to OFF, the process proceeds to step S420.

[0113] The control unit 130 performs color conversion on the luminal region in the frame based on the color information assigned to the frame extracted in step S412 (step S416). First, the control unit 130 performs processing on the frame including the luminal region B1 where m=1.

[0114] The control unit 130 converts the color tone of the angle information assigned to the frame in the information display area 204 of the examination screen 200 based on the color tone information assigned to the frame and displays the converted angle information (step S418).

[0115] As shown in FIG. 20, when the process for the luminal region B1 where m=1 is completed, the control unit 130 increments the variable m and sets m=2 (step S420).

[0116] The control unit 130 tracks, for each frame, the change in the depth direction of the m-th largest luminal region among the luminal regions extracted from n / 2 frames. Next, the control unit 130 extracts the frame including the luminal region with the shallowest display depth from the luminal regions of the tracked frames, and then cuts out image information IFm within the luminal region (step S422). Since m=2 is set in step S420, the control unit 130 performs processing on the frame including luminal region B2.

[0117] The control unit 130 determines whether the simple angle display mode is set to ON (step S424). If the control unit 130 determines that the simple angle display mode is set to ON, the process proceeds to step S426. On the other hand, if the control unit 130 determines that the simple angle display mode is set to OFF, the process proceeds to step S430.

[0118] The control unit 130 performs color tone conversion on the image information IFm based on the color tone information allocated to the frame of the image information IFm extracted in step S422 (step S426).

[0119] The control unit 130 converts the color tone of the angle information assigned to the frame based on the color tone information assigned to the frame and displays it in the information display area 204 of the examination screen 200 (step S428).

[0120] The control unit 130 combines the m-th largest lumen region in the frame that is used as the base frame with image information IFm clipped from another frame (step S430).

[0121] The control unit 130 determines whether m=s (step S432). If the variable m is s, the control unit 130 proceeds to step S434. On the other hand, if the control unit 130 determines that m=s is not true, the control unit 130 proceeds to step S436. The control unit 130 increments the variable m (m=m+1) and returns to step S420.

[0122] The control unit 130 displays the ultrasound image of the frame that is set as the base frame on the examination screen 200 of the display unit 120 (step S434). Specifically, as shown in Fig. 9 etc., the control unit 130 pastes and combines image information IFm cut out from the luminal region of another frame onto the luminal region of the base frame.

[0123] 19, if the control unit 130 determines that a lumen region has not been extracted from each of the ultrasound images of n frames, the process proceeds to step S444. In this case, all of the acquired ultrasound images of n frames have a luminance equal to or greater than a certain level, and are proper ultrasound images.

[0124] The control unit 130 extracts the frame with the highest average brightness of the entire region from among the n frames (step S444). After extracting the frame with the highest average brightness, the control unit 130 proceeds to step S446.

[0125] The control unit 130 determines whether the simple angle display mode is set to ON (step S446). If the control unit 130 determines that the simple angle display mode is set to ON, the process proceeds to step S448. On the other hand, if the control unit 130 determines that the simple angle display mode is set to OFF, the process proceeds to step S434 shown in FIG.

[0126] The control unit 130 displays the angle information assigned to the frame extracted in step S444 in the information display area 204 of the examination screen 200 (step S448). After displaying the angle information, the control unit 130 proceeds to step S434. The control unit 130 displays the ultrasound image of the frame extracted in step S444 in the image display area 202 of the examination screen 200 (step S434). As a result, the examination screen 200 simultaneously displays the ultrasound image of the frame including the luminal region B with the highest brightness, and the angle information of the ultrasound probe 150 when the ultrasound image was acquired.

[0127] The third embodiment can achieve substantially the same effects as the first embodiment. Specifically, according to the third embodiment, the control unit 130 extracts, in a predetermined frame, continuous luminal regions whose brightness difference is within a threshold value TB and tracks the change in the depth direction of the extracted luminal region in each frame. The control unit 130 then extracts the frame containing the luminal region with the shallowest display depth from the luminal regions in each tracked frame. In other words, by performing a tilting operation, a frame in which the ultrasonic probe 150 and the luminal region are most perpendicular can be automatically generated. This allows an optimal ultrasonic image to be acquired by tilting the ultrasonic probe 150 without using any additional equipment. As a result, an optimal ultrasonic image can be acquired with a simple operation without any special operations, and additional equipment is not required, thereby preventing an increase in costs. Furthermore, the operator can acquire an optimal ultrasonic image by simply tilting the ultrasonic probe 150 without being aware of the anisotropic reflection of the luminal structure.

[0128] While the preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, the technical scope of the present disclosure is not limited to such examples. Furthermore, various modifications and improvements will naturally fall within the technical scope of the present disclosure, provided that they are within the scope of the technical ideas described in the claims of those skilled in the art. [Explanation of symbols]

[0129] 1. Ultrasound diagnostic equipment 120 Display section 130 Control Unit 150 Ultrasound Probe F1, F2, F3, F4, F5 frames Ia,Ib,Ic,Id Angle information

Claims

1. 1. An ultrasound diagnostic device that transmits ultrasound waves into a subject, receives the ultrasound waves reflected by target tissue in the subject to obtain received signals, and outputs an ultrasound image of the target tissue based on the received signals, an acquisition unit that acquires a plurality of frames of ultrasound images when the angle of the ultrasound probe is changed by tilting the ultrasound probe; an extracting unit that extracts a reference frame including an ultrasound image when the ultrasound probe and the target tissue are perpendicular to each other from the plurality of frames acquired by the acquiring unit; an output unit that outputs the reference frame extracted by the extraction unit; An ultrasound diagnostic device comprising:

2. the extraction unit extracts image regions in which a luminance correlation value between image regions included in each of the plurality of frames is equal to or less than a threshold value; The ultrasonic diagnostic apparatus according to claim 1 .

3. the extraction unit extracts, as the reference frame, a frame including the image region having the highest average luminance among the extracted image regions; The ultrasonic diagnostic apparatus according to claim 2 .

4. When each of the plurality of frames includes at least a first image area and a second image area, the extraction unit extracts, from the plurality of frames, a first frame including the first image region having the highest average luminance as the reference frame; extracting a second frame including the second image region having the highest average luminance from the plurality of frames, cutting out the second image region from the second frame, and combining the cut-out second image region with the first image region of the first frame; The ultrasonic diagnostic apparatus according to claim 1 .

5. the extraction unit extracts a continuous lumen region in a predetermined frame among a plurality of frames, the lumen region having a brightness difference within a threshold value, tracks the depth of the extracted lumen region in the plurality of frames, and extracts a frame including the lumen region with the shallowest depth from the plurality of frames as the reference frame. The ultrasonic diagnostic apparatus according to claim 1 .

6. 1. An ultrasound diagnostic device that transmits ultrasound into a subject, receives the ultrasound reflected by a target tissue in the subject to obtain a received signal, and outputs an ultrasound image of the target tissue based on the received signal, an acquisition unit that acquires a plurality of frames of ultrasound images when the angle of the ultrasound probe is changed by tilting the ultrasound probe; a setting unit that allocates angle information of the ultrasonic probe with respect to the skin surface of the subject during tilting operation to each of the plurality of frames; An ultrasound diagnostic device comprising:

7. the setting unit sets color tone information for each of the angle information allocated to the plurality of frames. The ultrasonic diagnostic apparatus according to claim 6.

8. a computer of an ultrasound diagnostic apparatus that transmits ultrasound waves into a subject, receives the ultrasound waves reflected by a target tissue in the subject to obtain a received signal, and outputs an ultrasound image of the target tissue based on the received signal; an acquisition unit that acquires a plurality of frames of ultrasound images when the angle of the ultrasound probe is changed by tilting the ultrasound probe; an extracting unit that extracts a reference frame including an ultrasound image when the ultrasound probe and the target tissue are perpendicular to each other from the plurality of frames acquired by the acquiring unit; an output unit that outputs the reference frame extracted by the extraction unit; A program to function as a

9. 1. An ultrasound diagnostic method for an ultrasound diagnostic apparatus that transmits ultrasound into a subject, receives the ultrasound reflected by a target tissue in the subject to obtain a received signal, and outputs an ultrasound image of the target tissue based on the received signal, comprising: an acquiring step of acquiring a plurality of frames of ultrasound images when the angle of the ultrasound probe is changed by tilting the ultrasound probe; an extraction step of extracting a reference frame including an ultrasound image when the ultrasound probe and the target tissue are perpendicular to each other from the plurality of acquired frames; an output step of outputting the extracted reference frame; An ultrasound diagnostic method comprising:

10. A computer of an ultrasound diagnostic device that is capable of transmitting ultrasound waves into a subject, receiving the ultrasound waves reflected by a target tissue in the subject to obtain a received signal, and outputting an ultrasound image of the target tissue based on the received signal, an acquisition unit that acquires a plurality of frames of ultrasound images when the angle of the ultrasound probe is changed by tilting the ultrasound probe; a setting unit that assigns angle information of the ultrasonic probe with respect to the skin surface of the subject during tilting operation to each of the plurality of frames; A program to function as a

11. 1. An ultrasound diagnostic method capable of transmitting ultrasound into a subject, receiving the ultrasound reflected by a target tissue in the subject to obtain a received signal, and outputting an ultrasound image of the target tissue based on the received signal, comprising: an acquiring step of acquiring a plurality of frames of ultrasound images when the angle of the ultrasound probe is changed by tilting the ultrasound probe; a setting step of allocating angle information of the ultrasonic probe with respect to the skin surface of the subject during tilting operation to each of the plurality of frames; An ultrasound diagnostic method comprising:

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