Ultrasonic diagnostic apparatus

Abstract

The problem is to reduce artifacts due to specular reflection echo in color Doppler method with less computational load. The solution is that the ultrasound diagnostic apparatus according to the embodiments has a transmission unit, a reception unit, a beamforming unit, a filter unit, a principal component analysis unit, and a coherent superposition unit. The transmission unit repeatedly performs multiple ultrasonic wave transmissions with different transmission angles and / or transmission starting points. The reception unit receives multiple reception signals corresponding to the multiple ultrasonic wave transmissions, respectively. The beamforming unit applies beamforming to the multiple reception signals, respectively. The filter unit applies an MTI filter to each group of multiple initial images with the same transmission angle and / or transmission starting point. The principal component analysis unit applies principal component analysis to each packet of multiple MTI images. The coherent superposition unit applies coherent superposition to each packet of multiple principal component images to generate multiple coherent superposition images.

Description

[0001] Related applications:

[0002] This application enjoys priority based on Japanese Patent Application 2022-187722, filed on November 24, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The embodiments described herein generally relate to ultrasound diagnostic devices. Background Technology

[0004] Coherent Plane Wave Compounding (CPWC) is a known method that transmits multiple plane waves at different angles and coherently adds them together. CPWC has also been applied to color Doppler. CPWC is useful because it can achieve both high frame rates and high resolution, but it produces artifacts over a large area in the presence of specular reflectors, either horizontally or in circular arcs. These artifacts are particularly noticeable in color Doppler imaging where ultrasound is repeatedly transmitted over the same space.

[0005] Existing technical documents:

[0006] Patent Document 1: Japanese Patent Application Publication No. 2015-217172

[0007] Patent Document 2: Japanese Patent Application Publication No. 2018-122082 Summary of the Invention

[0008] The problem that the invention aims to solve:

[0009] One of the problems to be solved by the embodiments disclosed in this specification and accompanying drawings is to reduce artifacts caused by specular reflection echoes in color Doppler imaging with less computation. However, the problems to be solved by the embodiments disclosed in this specification and accompanying drawings are not limited to the above-mentioned problems. Problems corresponding to the effects of the various configurations shown in the embodiments described below can also be identified as other problems.

[0010] The ultrasound diagnostic apparatus according to the embodiment includes a transmitting unit, a receiving unit, a beamforming unit, a filtering unit, a principal component analysis unit, and a coherent superposition unit. The transmitting unit repeatedly transmits multiple ultrasound waves with different transmission angles and / or transmission starting points in packets via an ultrasound probe having multiple transducers. The receiving unit receives multiple received signals corresponding to the multiple ultrasound transmissions via the ultrasound probe. The beamforming unit applies beamforming to each of the multiple received signals to generate multiple initial images. The filtering unit applies an MTI filter to each group of the multiple initial images, based on the same transmission angle and / or transmission starting point, to generate multiple MTI images. The principal component analysis unit performs principal component analysis on each packet of the multiple MTI images to generate multiple principal component images. The coherent superposition unit applies coherent superposition to each packet of the multiple principal component images to generate multiple coherently superimposed images.

[0011] Invention effects:

[0012] The purpose of the invention is to reduce artifacts caused by specular reflection echoes in color Doppler imaging with less computation. Attached Figure Description

[0013] Figure 1 This is a diagram illustrating an example of the configuration of the ultrasonic diagnostic apparatus according to this embodiment.

[0014] Figure 2 This diagram illustrates the mechanism of specular reflection artifact generation during transmission focusing.

[0015] Figure 3 This diagram illustrates the mechanism of specular reflection artifacts during plane wave transmission.

[0016] Figure 4 This is an example of a blood flow image obtained by transmitting a plane wave in one direction using the energy display of color Doppler.

[0017] Figure 5 This diagram illustrates the process of an ultrasound examination performed by the ultrasound diagnostic apparatus according to this embodiment.

[0018] Figure 6 It is a schematic representation Figure 5 The diagram shows the procedure for an ultrasound examination.

[0019] Figure 7 It is used to explain in Figure 5 The diagram illustrates the mechanism by which principal component extraction, performed in step S4, mitigates specular artifacts.

[0020] Figure 8 This is an example in Figure 5The image of blood flow energy generated in step S6.

[0021] Figure 9 This diagram illustrates the generation mechanism of multiple reflection signals.

[0022] Figure 10 This is a diagram used to illustrate the transmission of the spread wave involved in Modification Example 1.

[0023] Figure 11 This is a diagram used to illustrate the telephoto transmission involved in Variation Example 2.

[0024] Explanation of reference numerals in the attached figures:

[0025] 100 Ultrasonic Diagnostic Device

[0026] 101 Ultrasonic Probe

[0027] 102 Main body of the device

[0028] 103 Transmitting Circuit

[0029] 104 Receiver Circuit

[0030] 105 Transceiver Control Circuit

[0031] 106 Beamforming Circuit

[0032] 107 Memory

[0033] 108 B-mode processing circuit

[0034] 109 Doppler processing circuit

[0035] 110 Processing Circuit

[0036] 111 Storage device

[0037] 112 Input devices

[0038] 113 Communication equipment

[0039] 114 Display Devices

[0040] 115 MTI filter circuit

[0041] 116 Principal Component Analysis Circuit

[0042] 117 Coherent Superposition Circuit

[0043] 118 Blood Flow Parameter Calculation Circuit Detailed Implementation

[0044] The ultrasound diagnostic apparatus according to the embodiment includes a transmitting unit, a receiving unit, a beamforming unit, a filtering unit, a principal component analysis unit, and a coherent superposition unit. The transmitting unit repeatedly transmits multiple ultrasound waves with different transmission angles and / or transmission starting points in packets via an ultrasound probe having multiple transducers. The receiving unit receives multiple received signals corresponding to the multiple ultrasound transmissions via the ultrasound probe. The beamforming unit applies beamforming to each of the multiple received signals to generate multiple initial images. The filtering unit applies an MTI filter to each group of the multiple initial images according to the same transmission angle and / or transmission starting point to generate multiple MTI images. The principal component analysis unit performs principal component analysis on each packet of the multiple MTI images to generate multiple principal component images. The coherent superposition unit applies coherent superposition to each packet of the multiple principal component images to generate multiple coherent superimposed images.

[0045] Hereinafter, the implementation of the ultrasonic diagnostic device will be described in detail with reference to the accompanying drawings.

[0046] Figure 1 This diagram illustrates a configuration example of the ultrasonic diagnostic apparatus 100 according to this embodiment. Figure 1 As shown, the ultrasonic diagnostic device 100 includes an ultrasonic probe 101 and a device body 102. The device body 102 includes a transmitting circuit 103, a receiving circuit 104, a transceiver control circuit 105, a beamforming circuit 106, a memory 107, a B-mode processing circuit 108, a Doppler processing circuit 109, a processing circuit 110, a storage device 111, a display device 114, an input device 112, and a communication device 113. The ultrasonic probe 101 is detachably connected to the device body 102.

[0047] Ultrasonic probe 101 is a probe responsible for transmitting and receiving ultrasonic waves. Ultrasonic probe 101 has multiple transducers arranged in one-dimensional or two-dimensional arrays. Each transducer receives a drive signal supplied from transmitting circuit 103 and transmits ultrasonic waves. Each drive signal is given a delay time to converge the ultrasonic waves transmitted from all ultrasonic probes 101 onto an arbitrary wavefront. The generated ultrasonic waves are reflected at the unconformity of the acoustic impedance within the target patient. Each transducer receives the reflected ultrasonic waves (reflected waves) within the target patient and converts them into echo signals. Ultrasonic probe 101 can also be a linear probe, a convex probe, a fan-shaped probe, or any other arbitrary arrangement.

[0048] The transmitting circuit 103 repeatedly transmits multiple ultrasonic waves with different transmission angles and / or transmission starting points in packets via an ultrasonic probe 101 having multiple oscillators. Specifically, the transmitting circuit 103, under the control of the transceiver control circuit 105, assigns a delay time to each oscillator and supplies a drive signal to enable the transmission of multiple ultrasonic waves with different transmission angles and / or transmission starting points. The transmitting circuit 103 repeatedly performs multiple ultrasonic wave transmissions so that the spatial region to which the ultrasonic waves are transmitted is repeated in the multiple ultrasonic wave transmissions. As the ultrasonic wave transmission method according to this embodiment, plane wave transmission, diffused wave transmission, or telephoto transmission can be used.

[0049] The receiving circuit 104 receives multiple received signals corresponding to the multiple ultrasonic waves transmitted by the transmitting circuit 103, via the ultrasonic probe 101. Specifically, the receiving circuit 104 is connected to multiple transducers mounted on the ultrasonic probe 101. Here, each transducer corresponds to a channel. The receiving circuit 104 has an amplifier circuit, an A / D conversion circuit, and a quadrature detector circuit for each channel. The amplifier circuit amplifies the echo signal from the transducer and performs gain correction processing. The A / D conversion circuit performs A / D conversion on the gain-corrected echo signal. The quadrature detector circuit converts the digital echo signal into a baseband in-phase signal (I signal) and a quadrature signal (Q signal). When I signals and Q signals are not specifically distinguished, they are referred to as received signals. The received signals are supplied to the beamforming circuit 106.

[0050] The transceiver control circuit 105 synchronously controls the transmitting circuit 103 and the receiving circuit 104 to perform ultrasonic scanning using multiple ultrasonic waves with different transmission angles and / or transmission starting points.

[0051] Beamforming circuit 106 applies beamforming to multiple received signals to generate multiple initial images. In other words, beamforming circuit 106 generates one initial image for each ultrasonic wave transmission. Each initial image represents the spatial distribution of reflected wave intensity values ​​in the receiving region corresponding to each ultrasonic wave transmission. As such a beamforming method, pixel beamforming is used in one example. Pixel beamforming is beamforming that calculates the complex pixel values ​​of pixels spatially located at the same position, independent of the transmission angle and / or transmission start point. Beamforming circuit 106 can be implemented by any processor.

[0052] The memory 107 stores the data of the initial image. The memory 107 can be any storage device such as RAM (Random Access Memory), ROM (Read Only Memory), or semiconductor storage device.

[0053] B-mode processing circuit 108 reads the initial image from memory 107 and applies B-mode processing to generate a B-mode image. Each pixel in the B-mode image represents the signal intensity of the reflected wave through its brightness value. B-mode processing circuit 108 can be implemented by any processor.

[0054] The Doppler processing circuit 109 reads the initial image from the memory 107 and applies color Doppler processing to generate a blood flow image. The Doppler processing circuit 109 of this embodiment generates a blood flow image with reduced artifacts included in the blood flow image due to specular reflection echoes. Figure 1 As shown, the Doppler processing circuit 109 includes an MTI filter circuit 115, a principal component analysis circuit 116, a coherent superposition circuit 117, and a blood flow parameter calculation circuit 118. The MTI filter circuit 115, the principal component analysis circuit 116, the coherent superposition circuit 117, and the blood flow parameter calculation circuit 118 can be implemented by any processor.

[0055] MTI filter circuit 115 applies an MTI (Moving Target Indicator) filter to each group of multiple initial images according to the same transmission angle and / or transmission start point, generating multiple MTI images. Principal component analysis circuit 116 performs principal component analysis on each packet of the multiple MTI images, generating multiple principal component images. Coherent superposition circuit 117 applies coherent superposition to each packet of the multiple principal component images, generating multiple coherent superimposed images. Blood flow parameter calculation circuit 118 applies blood flow parameter calculation processing to the multiple coherent superimposed images, generating a blood flow image representing the spatial distribution of blood flow parameters. Blood flow parameter calculation circuit 118 applies energy addition processing to the multiple coherent superimposed images, generating a blood flow energy image representing the spatial distribution of blood flow energy as a blood flow parameter, as a blood flow image. Furthermore, blood flow parameters, besides blood flow energy, can also be blood flow velocity or dispersion, etc.

[0056] The processing circuit 110 includes a processor such as a CPU (Central Processing Unit) that oversees and controls the ultrasound diagnostic device 100. The processing circuit 110 controls the transceiver control circuit 105, the B-mode processing circuit 108, the Doppler processing circuit 109, the storage device 111, the input device 112, the communication device 113, and the display device 114 by executing the ultrasound diagnostic program stored in the storage device 111. For example, the processing circuit 110 displays a blood flow image generated by the blood flow parameter calculation circuit 118 on the display device 114. The processing circuit 111 is an example of a display control unit.

[0057] Storage device 111 can be a storage device such as ROM, RAM, HDD (Hard Disk Drive), SSD (Solid State Drive), or integrated circuit storage device that stores various types of data. Alternatively, storage device 111 can also be a drive device that reads and writes various information to removable storage media such as CD-ROM drives, DVD drives, or flash memory. For example, storage device 111 stores the ultrasound diagnostic program of ultrasound diagnostic device 100.

[0058] Input device 112 is a user interface on a touch panel or operation panel. The operator can input various operations or commands for the ultrasound diagnostic apparatus 100 via input device 112. Alternatively, input device 112 can also be a voice recognition device that converts voice signals acquired by a microphone into instruction signals.

[0059] Communication device 113 is a communication interface that enables data communication between PACS (Picture Archiving and Communication System) servers, HIS (Hospital Information System) servers, MWM (Modality Worklist Management) servers, etc., via LAN (Local Area Network).

[0060] Display device 114 displays various data according to instructions from processing circuit 110. As display device 114, for example, a CRT monitor, liquid crystal display (LCD), CRT (cathode ray tube) monitor, organic EL (organic electroluminescent display), plasma display, or any other type of display can be suitably used. Furthermore, a projector can also be installed as display device 114.

[0061] The following describes the details of the ultrasonic diagnostic apparatus 100 according to this embodiment. In the following description, the ultrasonic wave transmission method is set to plane wave transmission. In plane wave transmission, the transmission circuit 103 performs multiple plane wave transmissions with different deflection angles, which are multiple ultrasonic wave transmissions with different transmission angles and / or transmission starting points. The deflection angle is defined by the angle between the central axis of the plane wave and the oscillator surface of the oscillator group.

[0062] Here, we will explain the artifacts caused by specular reflectors (hereinafter referred to as specular reflector artifacts) that are the target of mitigation in this embodiment.

[0063] Figure 2 This diagram illustrates the mechanism of specular reflection artifact generation during transmission focusing. Figure 3 This diagram illustrates the mechanism of specular reflection artifacts during plane wave transmission. (For example...) Figure 2 As shown, when transmission focusing is implemented, the strong echo from the specular reflector appears as an artifact only within the area where transmission focusing is implemented. However, as... Figure 3 As shown, artifacts appear over a wide area when plane waves are transmitted.

[0064] Figure 4 This is an example of a blood flow image obtained by transmitting a plane wave in one direction using color Doppler energy display. (Example) Figure 4 As shown, arc-shaped specular artifacts AF-1 and AF-2 appear in the blood flow image. These artifacts are caused by specular reflection at the brightest parts of the arc-shaped image. AF-1 and AF-2 tend to appear in areas such as heart valves, the heart wall, and the diaphragm. They do not disappear even when coherent plane wave composite (CPWC) is performed using multiple deflection angles. This is because the echo from the specular reflector is strong, and therefore does not disappear even when data from other deflection angles are added.

[0065] Figure 5 This diagram illustrates the process of an ultrasound examination performed by the ultrasound diagnostic apparatus 100 according to this embodiment. Figure 6 It is a schematic representation Figure 5 The diagram shows the procedure for an ultrasound examination. Furthermore, Figure 6 As an example, a case of plane wave transmission in three directions with 16 packets is illustrated. Here, a packet means a set of data corresponding to multiple plane wave transmissions performed sequentially at multiple transmission angles. Figure 6 In the example above, plane waves are sent in three directions per packet. The number of packets used to generate one blood flow image is 16. This number is called the number of packets to be processed. Furthermore, the number of plane wave transmissions per packet and the number of packets to be processed are not limited to the example above and can be set to any value.

[0066] like Figure 5 and Figure 6 As shown, the transmitting circuit 103 repeatedly transmits plane waves at multiple transmission angles (step S1). In Figure 6In the example, the transmitting circuit 103, under the control of the transceiver control circuit 105, sequentially and repeatedly transmits plane waves at three transmission angles θ1, θ2, and θ3 via the ultrasonic probe 101. In other words, multiple packets are repeatedly executed, with each packet consisting of three plane wave transmissions corresponding to the three transmission angles θ1, θ2, and θ3. The transducer groups of the transmitted plane waves can differ between packets; that is, the scanning areas can also differ. The plane waves are reflected by the internal tissues of the subject. The reflected waves are converted into echo signals by the ultrasonic probe 101. The echo signals are converted into received signals by the receiving circuit 104. One received signal corresponds to one plane wave transmission.

[0067] A single packet PA comprises three plane waves with transmission angles θ1, θ2, and θ3, which are repeatedly transmitted over the spatial region of the target object. The transmission angle θ is defined as the angle between the plane wave and the transmission surface of the transducer group of the ultrasonic probe 101. Transmission angle θ2 is set to θ = 0. Transmission angle θ1 is a positive angle relative to transmission angle θ2, and transmission angle θ3 is a negative angle relative to transmission angle θ2. Of course, the types of transmission angles θ are not limited to three; two or more types are acceptable, and the number is not limited.

[0068] If step S1 is performed, the beamforming circuit 106 performs pixel beamforming for each plane wave transmitted (step S2). Pixel beamforming refers to the beamforming process that calculates the complex pixel values ​​of pixels spatially located at the same position regardless of the transmission angle. In step S2, the beamforming circuit 106 applies pixel beamforming to the received signal for each plane wave transmitted, generating an initial image.

[0069] If step S2 is performed, the MTI filter circuit 115 applies the MTI filter in units of transmission angle (step S3). In step S3, the MTI filter circuit 115 selects from the initial images generated in the time series those belonging to the number of packets from the current backtracking processing object (in Figure 6 In the case of 16 packets, multiple initial images are selected as processing objects. The MTI filter circuit 115 applies an MTI filter to the multiple initial images of the selected processing objects. Steps S3 to S7 are executed each time the latest packet is transmitted ultrasonically.

[0070] Specifically, the MTI filter circuit 115 collects initial images belonging to the same transmission angle from multiple initial images of the processing object, with the number of initial images equal to the number of processing object packets, and applies an MTI filter. For example, if packet PA16 is the processing object packet and the transmission angle of the processing object is θ2, initial images of transmission angle θ2 are collected from the 16 most recent packets PA16 to PA1, and an MTI filter is applied to the 16 initial images related to transmission angle θ2. Then, the MTI filter circuit 115 outputs the image after applying the MTI filter (MTI image). An MTI image is generated for each transmission angle of each packet.

[0071] MTI filters are filters that remove tissue components from image data and extract only the blood flow component. Specifically, MTI filters are implemented using high-pass filters that are dependent on the packet direction. Here, the packet direction corresponds to the forward or backward direction of transmission. MTI filters can also use filters that perform principal component analysis dependent on the packet direction and output components other than the principal components as blood flow components.

[0072] If step S3 is performed, the principal component analysis circuit 116 performs principal component extraction on a packet-by-packet basis (step S4). More specifically, in step S4, the principal component analysis circuit 116 performs principal component analysis and extracts principal components on a packet PA-by-packet basis, in relation to the transmission angle θ direction, for the MTI image generated in step S3. For example, principal component extraction processing is applied to the MTI images of transmission angle θ1, transmission angle θ2, and transmission angle θ3 associated with packet PA16. Through principal component extraction processing, specular artifacts caused by anomalies in echo intensity relative to the transmission angle can be mitigated. The image associated with the extracted principal components is output as a principal component image.

[0073] The principal component analysis process in step S4 is as follows. First, the input signal vector x in step S4... i，j The mathematical expression is given by equation (1) below. Here, the input signal vector x i，j This means a vector representation of the pixel values ​​in an MTI image. i = 1 to Nx × Nz. Nx is the number of data points in the azimuth direction, and Nz is the number of data points in the depth direction. j = 1 to L. L is the packet number. Figure 6 In the example case, it is 16. N θ It is the number of sending angles, in Figure 6 In the example case, it is 3.

[0074]

[0075] Principal component analysis circuit 116 is based on input signal vector x i，j Calculate the correlation matrix Rxx. The correlation matrix Rxx It is expressed by the following equation (2). In equation (2), H represents the complex conjugate transpose.

[0076]

[0077] Principal component analysis circuit 116 pairs of correlation matrices R xx Perform eigenvalue decomposition and calculate the correlation matrix R. xx The diagonal matrix. Correlation matrix R xx The diagonal matrix D is represented by the following equation (3). The diagonal matrix D in equation (3) is a diagonal matrix with eigenvalues ​​as diagonal elements. V is an orthogonal matrix.

[0078] R xx =VDV H (3)

[0079] Principal component analysis circuit 116 selects the N contained in the diagonal matrix D. θ m (0 < m < N) in the principal components θ ) principal components. From N θ From the principal components, m principal components are selected in descending order. The selected m principal components λ... i The diagonal matrix E formed by (0 < i < m) is expressed by the following equation (4). Furthermore, the number m can be set to any value.

[0080]

[0081] Principal component analysis circuit 116 generates a filter (hereinafter referred to as principal component filter) based on diagonal matrix E and orthogonal matrix V to extract the m principal components of the higher byte. The principal component filter W is expressed by the following equation (5). The principal component filter W is generated for each packet.

[0082] W = VEV H (5)

[0083] Principal component analysis circuit 116, as shown in equation (6) below, applies principal component filter W to MTI image (input signal vector) x. i，j Generate an image that represents only the principal components of the MTI image (hereinafter referred to as the principal component image). i，j .

[0084] y i，j =Wx i，j (6)

[0085] Here, we explain the mechanism by which the extraction of principal components reduces specular artifacts. Figure 7 This diagram illustrates the mechanism by which principal component extraction reduces specular artifacts. (Example) Figure 7As shown, a plane wave transmission and reception is envisioned using five transmission angles T11 to T15. When the transmission angle θ = 0°, such as transmission angle T13, i.e., when the plane wave generated from the transducer group 81 included in the ultrasonic probe 101 is incident perpendicularly relative to the specular reflector 82, a strong specular reflection signal is generated, which is a significant cause of specular reflector artifacts. On the other hand, when the transmission angle θ ≠ 0°, such as transmission angles T11, T12, T14, and T15, i.e., when the plane wave generated from the transducer group 81 is incident obliquely relative to the specular reflector 82, a weak reflection signal is generated. Thus, the specular reflection signal is highly angle-dependent, making it impossible for it to become a principal component among the reflection signals at multiple transmission angles T11 to T15. Therefore, by applying a principal component filter to the MTI image, specular reflector artifacts can be mitigated.

[0086] If step S4 is performed, the coherent superposition circuit 117 performs coherent superposition on a packet-by-packet basis (step S5). In step S5, the coherent superposition circuit 117 applies coherent superposition to the principal component images of transmission angle θ1, transmission angle θ2, and transmission angle θ3 associated with each packet PA, thereby generating a coherent superimposed image. Based on the principal component image z i，j The coherent superimposed image z is generated according to the following equation (7). i，j Furthermore, T in equation (7) is a transpose.

[0087] z i，j =y i，j T y i，j (7)

[0088] If step S5 is performed, the blood flow parameter calculation circuit 118 performs energy summation across multiple packets (step S6). In step S6, the blood flow parameter is set as blood flow energy. In this case, in step S6, the blood flow parameter calculation circuit 118 calculates the blood flow parameter per pixel based on the principal component images of the transmission angles θ1 to θ3 associated with the 16 packets PA1 to PA16, generating a blood flow energy image representing the spatial distribution of the blood flow parameter. According to the following equation (8), based on the coherent superimposed image z i，j Generate blood flow energy image P i As mentioned above, i = 1 ~ Nx × Nz, therefore the blood flow energy image P i It is a two-dimensional image.

[0089]

[0090] If step S6 is performed, the processing circuit 110 displays the blood flow energy image (step S7). In step S7, the processing circuit 110 displays the blood flow energy image generated in step S6 on the display device 114. The blood flow energy image is generated in a time series and is therefore displayed as a dynamic image. Of course, the blood flow energy image of the desired frame can also be displayed as a still image.

[0091] Figure 8 This is an example of a blood flow energy image. In a blood flow energy image, each pixel is assigned a color value corresponding to the blood flow energy. For example... Figure 8 As shown, based on the blood flow energy image generated in step S6, and... Figure 4 Compared to the blood flow energy images shown, specular artifacts are removed or reduced. Therefore, high-quality blood flow images can be displayed, showing reduced or eliminated specular artifacts in areas prone to producing them, such as heart valves, heart wall, and diaphragm. This is expected to improve the accuracy of ultrasound image diagnosis.

[0092] In addition to removing strong reflection signals caused by specular reflection, this embodiment is also effective in removing multiple reflections. Figure 9 This is a diagram used to illustrate the generation mechanism of multiple reflection signals. For example... Figure 9 As shown, the focus is on the reflected signal that is transmitted through the boundary surface 91 of the first tissue observed from the ultrasonic probe 101 and reflected at the boundary surface 92 of the second tissue. In this case, the reflected signal that is reflected at the boundary surface 92 and transmitted through the boundary surface 91 and received by the ultrasonic probe 101 is called the correct reflected signal. On the other hand, the reflected wave reflected at the boundary surface 92 is further reflected sequentially at the boundary surfaces 91 and 92 and transmitted through the boundary surface 91, and the reflected signal received by the ultrasonic probe 101 is called the multiple reflection signal. In addition, the reflected signal that is received by the ultrasonic probe 101 after multiple round trips between the boundary surfaces 91 and 92 is also a multiple reflection signal. Apart from specular reflection, the signal level of the multiple reflection signal is small, so the multiple reflection signal will not become the principal component when plane waves are transmitted at multiple transmission angles. Therefore, the multiple reflection signal component can also be removed or reduced by the principal component extraction processing involved in this embodiment.

[0093] Thus, the ultrasonic examination described in this embodiment is completed.

[0094] also, Figure 5 and Figure 6 The ultrasound examination shown is one example; modifications, additions, and / or deletions can be made as appropriate without departing from the spirit of this embodiment. For example, in Figure 7The system is configured to generate a blood flow energy image, but it can also generate and display a blood flow velocity image where the blood flow parameter is velocity, or a blood flow dispersion image where the blood flow parameter is dispersion, etc. As another example, the B-mode processing circuit 108 can apply B-mode processing to the initial image in parallel with steps S3 to S6 to generate a B-mode image. In this case, the blood flow energy image and the B-mode image can be displayed overlapping or side-by-side.

[0095] As described above, the ultrasonic diagnostic apparatus according to this embodiment includes a transmitting circuit 103, a receiving circuit 104, a beamforming circuit 106, an MTI filter circuit 115, a principal component analysis circuit 116, and a coherent superposition circuit 117. The transmitting circuit 103 repeatedly transmits multiple ultrasonic waves with different transmission angles and / or transmission starting points in packets via an ultrasonic probe 101 having multiple oscillators. The receiving circuit 104 receives multiple received signals corresponding to the multiple ultrasonic wave transmissions via the ultrasonic probe 101. The beamforming circuit 106 applies beamforming to each of the multiple received signals to generate multiple initial images. The MTI filter circuit 115 applies an MTI filter to each group of the multiple initial images with the same transmission angle and / or transmission starting point to generate multiple MTI images. The principal component analysis circuit 116 performs principal component analysis on each packet of the multiple MTI images to generate multiple principal component images. The coherent superposition circuit 117 applies coherent superposition to each packet of the multiple principal component images to generate a coherent superimposed image.

[0096] Based on the above configuration, specular reflector artifacts that are highly dependent on the angle of the transmitted ultrasonic waves can be removed or mitigated through principal component analysis involving multiple transmission angles. Furthermore, since beamforming is performed for each ultrasonic wave transmission, principal component analysis is performed with respect to the transmission angle direction, thus enabling completion with a relatively light computational load.

[0097] Furthermore, when performing plane wave transmission as ultrasound transmission, principal component analysis involving multiple deflection angles is conducted. This allows for the removal or reduction of specular reflection artifacts present in blood flow images obtained via color Doppler imaging using CPWC.

[0098] (Variation Example 1)

[0099] In the above embodiment, the ultrasonic wave transmission is configured as a plane wave transmission. In Modification 1, the ultrasonic wave transmission is configured as a diffuse wave transmission. Hereinafter, the ultrasonic diagnostic apparatus 100 according to Modification 1 will be described. Furthermore, in the following description, components having substantially the same function as in this embodiment will be marked with the same reference numerals and will be described repeatedly only where necessary.

[0100] In Modification 1, the transmitting circuit 103 transmits multiple diffused waves with different transmission angles and / or transmission delay center points repeatedly in packets via an ultrasonic probe 101 having multiple oscillators. The transmission delay center point is an example of the transmission start point. The ultrasonic probe 101 in Modification 1 can be any probe capable of transmitting diffused waves, and can also be a linear probe, a convex probe, a fan-shaped probe, or any other arbitrary arrangement.

[0101] Figure 10 This diagram illustrates the spread wave transmission involved in Modification Example 1. Plane wave transmission is the transmission of ultrasonic waves that do not spread in the depth direction, as opposed to... Figure 10 As shown, diffuse wave transmission means the transmission of ultrasonic waves that gradually diffuse in the depth direction. The transmission direction of the diffuse wave is defined by a combination of the transmission angle and the transmission delay center point 83. The transmission angle is defined as the angle between the central axis of the transmitted diffuse wave and the transmission surface of the transducer group 81. The transmission delay center point 83 is a virtual wave source for the transmitted diffuse wave. The diffuse wave is transmitted from the transducer group 81 to any transmission angle using the transmission delay center point 83 as the virtual wave source.

[0102] When the transmission angle θ = 0°, such as transmission angle T22, that is, when the diffused wave generated from the oscillator group 81 is incident perpendicularly to the specular reflector 82, a strong specular reflection signal is generated, which is a major cause of specular reflector artifacts. In this case, the transmission delay center point 83 is located directly above the central axis of the oscillator group 81. On the other hand, when the transmission angle θ ≠ 0°, such as transmission angles T21 and T23, that is, when the diffused wave generated from the oscillator group 81 is incident obliquely to the specular reflector 82, a weak reflection signal is generated. Thus, the specular reflection signal is highly angle-dependent, and therefore cannot be a principal component among the reflection signals at multiple transmission angles T21 to T23. Therefore, by applying a principal component filter to the MTI image, specular reflector artifacts can be mitigated.

[0103] Furthermore, the transmission delay center point 83 is set to different positions depending on the transmission angle. In the case of transmission angle T21, the transmission delay center point 83 is located at the lower right of the paper compared to the case of transmission angle T22; in the case of transmission angle T23, the transmission delay center point 83 is located at the lower left of the paper compared to the case of transmission angle T22.

[0104] In the ultrasound examination processing involved in Modification Example 1, the only difference from the above embodiment is that the ultrasound transmission is changed from plane wave transmission to diffuse wave transmission; all other aspects are the same as the above embodiment. Therefore, by using diffuse wave transmission, it is also possible to reduce the artifacts in the blood flow image caused by specular reflection echoes with less computation.

[0105] (Variation Example 2)

[0106] In the above-described embodiment and Modification 1, an initial image of the entire region is generated by pixel beamforming based on the received signal from a single ultrasonic wave transmission. In Modification 2, the initial image of the entire region may not necessarily be generated based on the received signal from a single ultrasonic wave transmission. The beamforming circuit 106 in Modification 2 generates an initial image related to a repeating region of multiple ultrasonic waves transmissions with different transmission angles and / or transmission starting points. The ultrasonic wave transmission in Modification 2 is configured as a telephoto transmission. Hereinafter, the ultrasonic diagnostic apparatus 100 according to Modification 2 will be described. Furthermore, in the following description, components having substantially the same function as in this embodiment will be marked with the same reference numerals and will be described repeatedly only where necessary.

[0107] In Modification 2, the transmitting circuit 103 repeatedly performs multiple telephoto transmissions with different transmission angles and / or transmission focal positions in a packet-like manner via an ultrasonic probe 101 having multiple transducers. The transmission focal position is an example of the transmission starting point. The telephoto transmission direction is defined by a combination of the transmission angle and the transmission focal position. The transmission angle is defined as the angle between the central axis of the transmitted ultrasonic wave and the transducer surfaces of the transducer group. The transmission focal position is the focal position of the transmitted ultrasonic wave set relative to the transducer group in a specified depth direction. Telephoto transmission involves setting the transmission focal position at a location deeper than the depth of field. By setting the transmission focal position at a location deeper than the depth of field, a relatively flat transmitted sound field can be formed. In such cases, specular artifacts may also occur. Furthermore, the ultrasonic probe 101 in Modification 2 can be a linear probe, a convex probe, a fan-shaped probe, or any other arbitrary arrangement, as long as it can perform telephoto transmission.

[0108] In Modification 2, the transmitting circuit 103 transmits multiple telephoto signals with different focal points via an ultrasonic probe 101 having multiple transducers for each packet. In the multiple telephoto signals included in one packet, the transmission angle and / or the transmission focal point position are set differently. That is, the spatial positions of the multiple receiving areas corresponding to each of the multiple telephoto signals are different. Here, the transmission focal point position of each telephoto signal is set so that several spatially adjacent receiving areas among the multiple receiving areas corresponding to each telephoto signal are repeated. Thus, a large area of ​​repetition can be obtained as a whole for the multiple telephoto signals. Furthermore, the transducer group (hereinafter referred to as the driving element group) used for ultrasonic transmission can be changed accordingly with the transmission focal point position. For example, by sequentially moving the driving element group from one end to the other of the entire transducer group (transducer array) included in the ultrasonic probe 101, a larger area can be ultrasonically scanned.

[0109] Figure 11This is a diagram used to illustrate the telephoto transmission involved in Modification Example 2. For example... Figure 11 The illustration shows a telephoto transmission associated with three transmission directions T31, T32, and T33 included in a single packet. In each telephoto transmission, a transmission angle and a transmission focus position 84 are set so that the receiving areas 851, 852, and 853 corresponding to the telephoto transmissions T31, T32, and T33 overlap. The overlapping area 86 is obtained by combining the receiving areas 851, 852, and 853.

[0110] like Figure 11 As shown, a region of the specular reflector 82 is contained within three receiving regions 851, 852, and 853, with the transmitting wavefront arriving at different angles relative to the specular reflector 82. For example, in the transmitting direction T32, the transmitting wavefront arrives parallel to the specular reflector 82, thus generating a specular reflection signal. However, in other transmitting directions T31 and T33, the transmitting wavefront arrives at an angle relative to the specular reflector 82, thus not generating a specular reflection signal. Because the specular reflection signal is highly angle-dependent, it is unlikely to be a principal component among the reflection signals in the multiple transmitting directions T31 to T33. Therefore, by applying a principal component filter to the MTI image, specular reflector artifacts can be mitigated.

[0111] In Modification 2, the beamforming circuit 106 and Doppler processing circuit 109 perform the same processing as in this embodiment for the overlapping regions of the multiple receiving regions corresponding to the multiple telephoto transmissions. Therefore, artifacts caused by specular reflection echoes in the blood flow image can be reduced with less computation. By processing the overlapping regions, it is expected to improve the S(Signal) / N(Noise) ratio of the blood flow image compared to plane wave transmission or diffuse wave transmission. Furthermore, the number of data points Nx in the azimuth direction and the number of data points Nz in the depth direction related to the above equation (1) are limited to data points within the overlapping regions. The spatial location and range of the overlapping regions are preset by the user or the system.

[0112] According to at least one embodiment described above, artifacts caused by specular reflection echoes in color Doppler imaging can be reduced with less computation.

[0113] The term "processor" used in the above description refers to circuits such as CPU, GPU, or Application Specific Integrated Circuit (ASIC), programmable logic device (e.g., Simple Programmable Logic Device (SPLD), Complex Programmable Logic Device (CPLD), and Field Programmable Gate Array (FPGA)). The processor implements its function by reading and executing a program stored in a memory circuit. Alternatively, instead of storing the program in a memory circuit, the program can be directly loaded into the processor's circuitry. In this case, the processor implements its function by reading and executing the program loaded into the circuitry. On the other hand, if the processor is, for example, an ASIC, the program is not stored in a memory circuit, but rather the function is directly assembled into the processor's circuitry as logic circuitry. Furthermore, the processors in this embodiment are not limited to being configured as a single circuit for each processor; multiple independent circuits can be combined to form a single processor and implement its function. Furthermore, it is also possible to... Figure 1 The multiple components are integrated into a single processor to perform their functions.

[0114] Several embodiments have been described above, but these embodiments are given as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other ways, and various omissions, substitutions, modifications, and combinations of embodiments are possible without departing from the spirit of the invention. These embodiments and their variations are included in the scope or spirit of the invention, and are included in the scope of the invention as described in the claims and its equivalents.

Claims

1. An ultrasonic diagnostic device, wherein, have: The transmitting unit, via an ultrasonic probe with multiple oscillators, repeatedly transmits multiple ultrasonic waves with different transmission angles and / or transmission starting points in a package-like manner. The receiving unit receives multiple received signals corresponding to the multiple ultrasonic waves transmitted, via the ultrasonic probe. The beamforming unit applies beamforming to the multiple received signals respectively to generate multiple initial images; The filter unit applies an MTI filter to each group of the plurality of initial images according to the same transmission angle and / or transmission start point, thereby generating a plurality of MTI images; The principal component analysis unit performs principal component analysis on each of the multiple MTI images to generate multiple principal component images. as well as The coherent overlay section applies coherent overlay to each of the multiple principal component images to generate multiple coherent overlay images.

2. The ultrasonic diagnostic device as described in claim 1, wherein, It also has: The blood flow parameter calculation and processing unit applies blood flow parameter calculation and processing to the multiple coherent superimposed images to generate a blood flow image that represents the spatial distribution of blood flow parameters.

3. The ultrasonic diagnostic device as described in claim 2, wherein, It also has: The display control unit displays the blood flow image on a display device.

4. The ultrasonic diagnostic device as described in claim 2, wherein, The blood flow parameter processing unit applies energy addition processing to the multiple coherent superimposed images to generate a blood flow energy image as the blood flow image, which represents the spatial distribution of blood flow energy as the blood flow parameter.

5. The ultrasonic diagnostic device as described in claim 1, wherein, The transmitting unit repeatedly transmits the plurality of ultrasonic waves so that the spatial region to which the ultrasonic waves are transmitted is repeated in the plurality of ultrasonic wave transmissions.

6. The ultrasonic diagnostic device as described in claim 1, wherein, The transmitting unit performs multiple plane wave transmissions with different deflection angles, which are the multiple ultrasonic waves with different transmission angles and / or transmission starting points.

7. The ultrasonic diagnostic device as claimed in claim 1, wherein, The transmitting unit performs multiple diffusion wave transmissions as the multiple ultrasonic wave transmissions.

8. The ultrasonic diagnostic device as described in claim 1, wherein, The transmitting unit performs multiple telephoto transmissions as multiple ultrasonic wave transmissions.

9. The ultrasonic diagnostic device as claimed in claim 1, wherein, The beamforming unit applies pixel beamforming as the beamforming, and the pixel beamforming calculates the complex pixel values ​​of pixels that are spatially located at the same position without depending on the transmission angle and / or transmission start point.

10. The ultrasonic diagnostic apparatus as claimed in claim 1, wherein, The filter unit applies the MTI filter only to the plurality of initial images belonging to a specified number of packets traced back from the current position.

Images