Ultrasound diagnostic device and control method thereof

Abstract

To allow a user to easily know a limit of depth at which color information based on blood flow information in an ultrasonic diagnostic apparatus is displayed.SOLUTION: A medical image diagnostic apparatus according to an embodiment comprises: a first acquisition unit which acquires an ultrasonic image in a living body of a subject; a second acquisition unit which acquires blood flow information in the ultrasonic image acquired by the first acquisition unit and generates color information on the basis of the acquired blood flow information; a superimposition display unit which displays the generated color information so as to be superimposed on an ultrasonic image acquired by the first acquisition unit; and a calculation unit which calculates a limit of depth at which color information is displayed by the superimposition display unit on the basis of attenuation of a signal generated in the living body.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The embodiments disclosed in the present specification and drawings relate to an ultrasound diagnostic apparatus and a control method thereof. [Background technology]

[0002] An ultrasound diagnostic device is a device that transmits ultrasonic pulses generated by a piezoelectric vibrator built into an ultrasound probe into the body of a subject, receives reflected wave signals from the subject's tissue and blood flow using the piezoelectric vibrator, and generates image data, etc.

[0003] To observe the dynamics of blood flow, users such as doctors and technicians using ultrasound diagnostic equipment use color mode to determine the presence or absence of blood flow and estimate the approximate blood flow velocity. Color mode, also known as color flow mapping (CFM), is a mode in which blood flow information, including blood flow velocity and direction, is superimposed on a B (brightness) mode image and displayed in real time. In color mode, blood flow velocity and direction are expressed using color information that combines hues such as red and blue and brightness. After grasping the approximate blood flow velocity in color mode, users transition to PWD (Pulsed Wave Doppler) mode or CWD (Continuous Wave Doppler) mode and use the measurement functions to obtain more accurate blood flow velocity.

[0004] However, when observing blood flow in this color mode, blood flow (blood vessels) within the user's region of interest (ROI) may not be colored. In particular, when it comes to deep blood flow (blood vessels), there are generally limitations to the performance of ultrasound diagnostic equipment and the sensitivity of the probe. In such cases, users may become confused and not understand why the blood flow is not colored. Furthermore, depending on the situation, users may mistakenly conclude that there is no blood flow. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-342586 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-233859 [Patent Document 3] Japanese Patent Publication No. 2020-39841 Summary of the Invention [Problem to be solved by the invention]

[0006] One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to enable a user to easily know the depth limit at which color information based on blood flow information is displayed in an ultrasound diagnostic device. However, the problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above problem. Problems corresponding to the effects of each configuration shown in the embodiments described below can also be positioned as other problems. [Means for solving the problem]

[0007] A medical image diagnostic device according to an embodiment includes a first acquisition unit that acquires an ultrasound image of a subject inside the living body, a second acquisition unit that acquires blood flow information in the ultrasound image acquired by the first acquisition unit and generates color information based on the acquired blood flow information, an overlay display unit that displays the generated color information by superimposing it on the ultrasound image acquired by the first acquisition unit, and a calculation unit that calculates a limit to the depth at which the color information is displayed on the overlay display unit based on signal attenuation that occurs inside the living body. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a block diagram showing the configuration of an ultrasound diagnostic system including an ultrasound diagnostic apparatus according to the present embodiment. [Figure 2] FIG. 10 is a diagram showing an example of an ultrasound image in which color information based on blood flow is displayed in color mode due to the presence of blood vessels in the shallow part of the image. [Figure 3]FIG. 10 is a diagram showing an example of an ultrasound image in which color information based on blood flow is not displayed in color mode due to the presence of blood vessels deep within the image. [Figure 4] FIG. 4 is a flowchart illustrating the content of color mode display processing executed by the ultrasound diagnostic apparatus according to the present embodiment. [Figure 5] FIG. 1 is a graph showing the difference in sensitivity as a performance of an ultrasound diagnostic device or an ultrasound probe, based on the relationship between depth and signal intensity. [Figure 6] FIG. 10 is a graph showing the difference in the strength of attenuation of an ultrasonic signal within a living body based on the relationship between depth and signal intensity. [Figure 7] FIG. 10 is a graph showing the signal intensity of a reflected wave signal in a phantom under ideal conditions. [Figure 8] 8 is a graph showing the relationship between signal strength and depth when attenuation in vivo is greater than the ideal condition shown in FIG. 7. [Figure 9] FIG. 8 is a graph showing the relationship between signal strength and depth when attenuation in the living body is smaller than the ideal condition shown in FIG. 7 . [Figure 10] FIG. 10 is a diagram showing an example of a user notification in which the movement of a region of interest identification display that identifies a region of interest within an ultrasound image is restricted to notify the user of the depth limit at which color information is displayed. [Figure 11] FIG. 10 is a diagram showing an example of displaying a marker together with an ultrasound image according to the depth limit at which color information based on blood flow information is displayed, as an example of user notification. [Figure 12] FIG. 10 is a diagram showing an example of a user notification informing a user to change the frequency of ultrasound transmitted into the living body of a subject to acquire blood flow information. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of an ultrasound diagnostic apparatus and a control method thereof will be described with reference to the drawings. In the following description, components having substantially the same functions and configurations are designated by the same reference numerals, and redundant explanations will be given only when necessary.

[0010] FIG. 1 is a block diagram showing the configuration of an ultrasound diagnostic system 1 including an ultrasound diagnostic device 100 according to one embodiment. The ultrasound diagnostic system 1 according to this embodiment is configured to include an ultrasound probe 10, an external device 20, and the ultrasound diagnostic device 100. The external device 20 and the ultrasound diagnostic device 100 are connected via a network NW such as a wide area network (WAN), a local area network (LAN), the Internet, a dedicated line, a wireless base station, or a provider. In this embodiment, the ultrasound probe 10 is not included in the configuration of the ultrasound diagnostic device 100, but the ultrasound probe 10 may be included in the configuration of the ultrasound diagnostic device 100.

[0011] The ultrasonic probe 10 performs an ultrasonic scan of a scan region within a living body P, which is a subject, under the control of, for example, the ultrasonic diagnostic device 100. The scan region is, for example, a region associated with the position and direction of the probe surface of the ultrasonic probe 10. The ultrasonic probe 10 includes, for example, a plurality of piezoelectric transducers, a matching layer provided on the piezoelectric transducers, and a backing material that prevents ultrasonic waves from propagating backward from the piezoelectric transducers. The ultrasonic probe 10 is, for example, a one-dimensional array linear probe in which a plurality of ultrasonic transducers are arranged along a predetermined direction. The ultrasonic probe 10 may be detachably connected to the ultrasonic diagnostic device 100, or multiple ultrasonic probes 10 may be connected to the ultrasonic diagnostic device 100. When multiple ultrasonic probes 10 are connected to the ultrasonic diagnostic device 100, an operator or the like can arbitrarily select which of the connected ultrasonic probes to use for the ultrasonic scan by performing a switching operation.

[0012] The external device 20 is, for example, a PACS (Picture Archiving and Communication System) that is a system for managing various types of medical image data, an electronic medical record system that manages electronic medical records to which medical images are attached, etc. The external device 20 may also be a storage device such as a storage server or a database.

[0013] The ultrasound diagnostic device 100 is configured to include, for example, an ultrasound transmission circuit 110, an ultrasound reception circuit 112, a signal processing circuit 120, a communication interface 130, an input interface 140, a display 150, a processing circuit 160, and a memory circuit 180.

[0014] The ultrasonic wave transmission circuit 110 transmits drive signals to the multiple piezoelectric vibrators of the ultrasonic probe 10, causing the piezoelectric vibrators to vibrate to generate ultrasonic waves. As a result, ultrasonic waves are transmitted from the surface (body surface) of the living body P that is in contact with the probe surface of the ultrasonic probe 10 to the inside.

[0015] The ultrasonic receiving circuit 112 receives signals generated when ultrasonic waves transmitted from the ultrasonic probe 10 are reflected by the tissues of the living body P, and the reflected signals (reflected wave signals) are received by multiple piezoelectric transducers and converted into electrical signals. When ultrasonic pulses transmitted into the living body P are reflected by the surface of a moving blood flow or the heart wall, the reflected wave signals undergo frequency shift due to the Doppler effect, depending on the velocity component of the moving object in the ultrasonic transmission direction. The ultrasonic receiving circuit 112 amplifies the reflected wave signals received by the ultrasonic probe 10 and converts them into digital signals. The ultrasonic receiving circuit 112 may also apply a delay time required to determine the reception directivity to the digital signals, and add up the multiple digital signals with the delay time to generate reception signals in which the reflection components from the direction corresponding to the reception directivity are emphasized.

[0016] The signal processing circuit 120 performs signal processing to generate ultrasound data based on the signal received by the ultrasound receiving circuit 112. The ultrasound data includes, for example, B-mode data. When generating B-mode data, the signal processing circuit 120 performs envelope detection processing, logarithmic amplification processing, etc. on the reception signal (reflected wave signal) received by the ultrasound receiving circuit 112, and generates B-mode data in which signal strength is expressed by brightness. In addition, the signal processing circuit 120 converts (scan converts), for example, a scan line signal sequence of the ultrasound scan into a scan line signal sequence in a format that can be displayed on the display 150, etc., and generates B-mode image data including B-mode data on two-dimensional ultrasound scan lines (raster) within the scan area. The B-mode image data may include information about the time of generation.

[0017] The ultrasound data may also include Doppler data. In this case, the signal processing circuit 120 performs frequency analysis based on the received signal received by the ultrasound receiving circuit 112 to generate Doppler data that extracts motion information based on the Doppler effect of a moving object within a region of interest (ROI) set in the scan region. For example, the signal processing circuit 120 generates Doppler data that estimates the average velocity, average variance, average power, etc. at each of multiple sample points as motion information of the object (moving object) included in the scan region. Here, the moving object refers to, for example, blood flow, tissue such as the heart wall, and a contrast agent. For example, the signal processing circuit 120 generates Doppler data that estimates the average velocity, average variance, average power, etc. of the blood flow at each of multiple sample points as motion information of the blood flow (blood flow information). Furthermore, the signal processing circuit 120, for example, scan-converts the scan line signal sequence of the ultrasound scan based on the generated Doppler data to generate Doppler image data including Doppler data on two-dimensional ultrasound scan lines within the ROI. The Doppler image data may include information about the time at which it was generated. In the following description, it is assumed that the ultrasound data mainly includes B-mode image data and Doppler data.

[0018] The communication interface 130 includes, for example, a communication interface such as a network interface card (NIC), etc. The communication interface 130 is connected to the external device 20 via the network NW, and performs data communication with the external device 20.

[0019] The input interface 140 accepts various input operations from an operator, converts the accepted input operations into electrical signals, and outputs the electrical signals to the processing circuitry 160. For example, the input interface 140 may be implemented by a mouse, keyboard, trackball, switch, button, joystick, touch panel, or the like. The input interface 140 may also be implemented by a user interface that accepts audio input from a microphone, for example. If the input interface 140 is a touch panel, the display 150, which will be described later, may be formed integrally with the input interface 140. Note that in this specification, the input interface 140 is not limited to those that include physical operating components such as a mouse and keyboard. For example, an electrical signal circuit that receives electrical signals corresponding to input operations from an external input device provided separately from the ultrasound diagnostic apparatus 100 and outputs the electrical signals to the processing circuitry 160 is also included as an example of the input interface 140.

[0020] The display 150 displays various types of information. For example, the display 150 displays an image generated by the processing circuit 160 in a predetermined display state, or displays a GUI (Graphical User Interface) for receiving various input operations from an operator. For example, the display 150 is an LCD (Liquid Crystal Display), a CRT (Cathode Ray Tube) display, an organic EL (Electro Luminescence) display, or the like.

[0021] In this embodiment, the processing circuitry 160 includes, for example, a first acquisition function 162, a second acquisition function 164, an overlap display function 166, a calculation function 168, a user notification function 170, and a region of interest movement function 172. However, the processing circuitry 160 may include functions other than these exemplified functions. The processing circuitry 160 realizes these functions by, for example, having the processor read and execute a program stored in the storage circuitry 180.

[0022] The processor refers to a circuit such as a central processing unit (CPU), a graphics processing unit (GPU), an application specific integrated circuit (ASIC), a programmable logic device (e.g., a simple programmable logic device (SPLD) or a complex programmable logic device (CPLD), or a field programmable gate array (FPGA)). Instead of storing the program in the storage circuit 180, the program may be directly embedded in the circuit of the processor. In this case, the processor realizes its function by reading and executing the program embedded in the circuit. The program may be stored in the storage circuit 180 in advance, or may be stored in a non-transitory storage medium such as a DVD or CD-ROM, and installed in the storage circuit 180 from the non-transitory storage medium when the non-transitory storage medium is inserted into a drive device (not shown) of the ultrasound diagnostic apparatus 100. The processor is not limited to being configured as a single circuit, but may be configured as a single processor by combining multiple independent circuits to realize each function, or multiple components may be integrated into a single processor to realize each function.

[0023] Here, the first acquisition function 162 constitutes the first acquisition unit in this embodiment, the second acquisition function 164 constitutes the second acquisition unit in this embodiment, the overlap display function 166 constitutes the overlap display unit in this embodiment, the calculation function 168 constitutes the calculation unit in this embodiment, the user notification function 170 constitutes the user notification unit in this embodiment, and the region of interest moving function 172 constitutes the region of interest moving unit in this embodiment.

[0024] The storage circuit 180 is realized by, for example, a semiconductor memory element such as a ROM (Read Only Memory) or a flash memory, a hard disk, an optical disk, or the like. These storage media, including non-transitory storage media, may be realized by other storage devices connected via a network NW, such as a NAS (Network Attached Storage) or an external storage server device. The storage circuit 180 may also include a transient storage medium such as a RAM (Random Access Memory) or a register. The storage circuit 180 stores, for example, programs executed by the processing circuit 160 and other information.

[0025] The first acquisition function 162 acquires a B-mode image by processing the B-mode image data processed by the signal processing circuit 120. The B-mode image acquired by the first acquisition function 162 becomes the ultrasound image displayed on the display 150 in this embodiment.

[0026] The second acquisition function 164 acquires blood flow information within the ultrasound image acquired by the first acquisition function 162. Then, the second acquisition function 164 generates color information based on this acquired blood flow information.

[0027] The superimposed display function 166 superimposes the color information generated by the second acquisition function 164 on the ultrasound image acquired by the first acquisition function 162 and displays it on the display 150, for example.

[0028] The calculation function 168 calculates the depth limit at which color information is displayed by the overlap display function 166 based on the attenuation of signals that occurs in the living body.

[0029] The user notification function 170 notifies the user of the depth limit at which color information based on blood flow information is displayed, calculated by the calculation function 168. The manner in which the user is notified is arbitrary.

[0030] Region of interest moving function 172 displays a region of interest identification display that identifies a region of interest that is an area of ​​interest for the user within the ultrasound image displayed on display 150, movable by a user operation. The user moves the region of interest identification display displayed on display 150, for example, by operating input interface 140. Then, user notification function 170 limits the movement of the region of interest identification display by region of interest moving function 172 in accordance with the depth limit calculated by calculation function 168 at which color information based on blood flow information is displayed.

[0031] Next, the reason why there is a limit to the depth at which color information based on blood flow information is displayed in the ultrasound diagnostic system 1 and ultrasound diagnostic device 100 according to this embodiment will be explained with reference to Figures 2 and 3. Figure 2 is a diagram showing an example of an ultrasound image in which color information based on blood flow is displayed in color mode, and Figure 3 is a diagram showing an example of an ultrasound image in which color information based on blood flow is not displayed in color mode.

[0032] As shown in Fig. 2, when blood flow information in the living body of a subject is normally acquired, color information based on the blood flow information is displayed on the ultrasound image, superimposed on the B-mode image. On the other hand, as shown in Fig. 3, when blood flow information in the living body of a subject cannot be normally acquired, color information based on the blood flow information is not displayed on the ultrasound image. This is because the ultrasound conditions for acquiring a B-mode image are different from the ultrasound conditions for acquiring blood flow information. In this embodiment, for ease of explanation, the ultrasound conditions for acquiring a B-mode image will be referred to as first conditions, and the ultrasound conditions for acquiring blood flow information will be referred to as second conditions.

[0033] In general, the conditions for ultrasound transmitted into a living body to acquire blood flow information (the second condition) make it more difficult for the ultrasound to reach deep inside the living body than the conditions for ultrasound transmitted into a living body to acquire a B-mode image (the first condition).As a result, although the B-mode image is displayed normally, color information based on the blood flow information is not added to the B-mode image.

[0034] A user viewing the ultrasound image shown in FIG. 3 may find it strange that blood vessels are present but blood flow information is not displayed as color information. Alternatively, the user may not realize that blood vessels exist and may make an erroneous judgment. For this reason, the ultrasound diagnostic device 100 and ultrasound diagnostic device 100 according to this embodiment calculate in advance the depth limit at which color information based on this blood flow information is displayed. Then, as necessary, the depth limit at which color information based on blood flow velocity is displayed is notified to the user.

[0035] Next, we will explain in detail the process of calculating in advance the depth limit at which color information based on this blood flow information is displayed, and the process of notifying the user of the depth limit at which color information based on blood flow velocity is displayed.

[0036] 4 is a flowchart illustrating the color mode display processing executed by the ultrasound diagnostic apparatus 100 according to this embodiment. This color mode display processing is executed, for example, when the user inputs an instruction to display an ultrasound image in color mode to the ultrasound diagnostic apparatus 100 via the input interface 140. Alternatively, this processing is executed when the user inputs an instruction to execute the color mode display via the input interface 140 when it becomes necessary to check the depth limit at which color information based on blood flow information is displayed.

[0037] The color mode display process according to this embodiment is realized, for example, by having a color mode display program stored in the memory circuitry 180 and having the processing circuitry 160 read and execute the color mode display program. The color mode display process realizes the first acquisition function 162, second acquisition function 164, overlap display function 166, calculation function 168, user notification function 170, and region of interest movement function 172 described above.

[0038] 4, first, the ultrasound diagnostic device 100 acquires a virtual ultrasound image (step S10). In this embodiment, the process of acquiring this virtual ultrasound image is realized by the calculation function 168 in the processing circuitry 160 of the ultrasound diagnostic device 100.

[0039] Specifically, the calculation function 168 transmits ultrasound from the ultrasound probe 10 into the subject's living body under the same conditions (second conditions) as those for transmitting ultrasound into the living body to acquire blood flow information. The ultrasound probe 10 then receives a reflected wave signal from the transmitted ultrasound reflected inside the living body and generates a virtual ultrasound image. This virtually generated ultrasound image is a virtual B-mode image, and in this embodiment, this will be referred to as a virtual ultrasound image. The virtual ultrasound image is used solely by the ultrasound diagnostic device 100 to calculate the depth limit at which color information is displayed, and is image data that is not displayed on the display 150 in this embodiment.

[0040] For example, if the frequency of ultrasound transmitted into a living body to generate a B-mode image is 1.5 MHz, the frequency of ultrasound transmitted into a living body to acquire blood flow information is 2.5 MHz. Generally, the lower the frequency, the deeper the ultrasound reaches within the living body and the more easily its reflected wave signal can be received. Therefore, in this example, the 2.5 MHz ultrasound for acquiring blood flow information is less likely to reach deeper within the living body than the 1.5 MHz ultrasound for generating a B-mode image. Therefore, in this embodiment, the 2.5 MHz ultrasound is transmitted into the living body, and the reflected wave signal is used to generate a virtual ultrasound image, which is then used to examine the attenuation of ultrasound occurring within the living body.

[0041] Next, the ultrasound diagnostic device 100 calculates the depth limit at which color information based on the blood flow information is displayed on the ultrasound image (step S12). In this embodiment, the process of calculating this depth limit is realized by the calculation function 168 in the processing circuitry 160 of the ultrasound diagnostic device 100.

[0042] Specifically, the calculation function 168 calculates the depth limit at which color information based on the blood flow information is displayed by superimposing it on the ultrasound image, based on a virtual ultrasound image acquired by transmitting ultrasound into the subject's living body under the second condition for acquiring blood flow information. For example, this depth limit can be calculated by observing changes in brightness within the virtual ultrasound image, because brightness in a B-mode image represents the strength of the reflected wave signal at that position.

[0043] In general, the depth to which color information as blood flow information can be displayed varies depending on the performance of the ultrasound diagnostic device 100, the performance of the ultrasound probe 10, the movement of the subject within the living body, the degree of attenuation of ultrasound signals within the living body, etc. The performance of the ultrasound diagnostic device 100 and the performance of the ultrasound probe 10 can be grasped in advance at the design stage. Taking into account attenuation within the living body, the deeper the depth within the living body, the weaker the reflected wave signal becomes, and at a certain depth, color information based on blood flow information cannot be displayed.

[0044] For example, by using a phantom or the like, it is possible to determine to what depth blood flow information can be observed. However, the attenuation of ultrasound within a living body varies depending on the part of the body. For example, amniotic fluid and the bladder contain a lot of water and therefore attenuate little. Conversely, muscles attenuate ultrasound significantly. Also, if the ultrasound probe 10 is a linear probe, scanning at an angle reduces the level of the reflected wave signal compared to scanning directly below.

[0045] FIG. 5 is a graph showing the difference in sensitivity as a performance feature of the ultrasound diagnostic device 100 and the ultrasound probe 10 based on the relationship between depth and signal strength. The vertical axis represents the signal strength of the received reflected wave signal, and the horizontal axis represents the depth within the living body. As can be seen from FIG. 5, when the sensitivity of the ultrasound diagnostic device 100 is high, the signal strength of the reflected wave signal even from a deep position is high. On the other hand, when the sensitivity of the ultrasound diagnostic device 100 is low, the signal strength of the reflected wave signal from a deep position is low.

[0046] Figure 6 is a graph showing the difference in the strength of ultrasonic signal attenuation within a living body based on the relationship between depth and signal strength. As with Figure 5, the vertical axis represents the signal strength of the received reflected wave signal, and the horizontal axis represents the depth within the living body. As can be seen from Figure 6, when attenuation within the living body is weak, the signal strength of the reflected wave signal even from a deep position is high. On the other hand, when attenuation within the living body is strong, the signal strength of the reflected wave signal from a deep position is low.

[0047] FIG. 7 is a graph showing the signal strength of a reflected wave signal in a phantom under an ideal condition. In this FIG. 7, the vertical axis also shows the signal strength of the received reflected wave signal, and the horizontal axis shows the depth inside the living body. In this example, under ideal conditions using a phantom, the signal strength of the reflected wave signal attenuates at a rate of 0.5 dB / MHz / cm. When the signal strength is expressed as an S / N ratio, if the S / N ratio drops below a certain level, sufficient blood flow information cannot be obtained, and color information cannot be generated. This signal strength (S / N ratio) is taken as the threshold X. In the example of FIG. 7, threshold X is reached at a depth of 16 cm from the body surface, and appropriate color information cannot be obtained in areas deeper than this.

[0048] Figure 8 shows the relationship between signal strength and depth when attenuation within the living body is greater than the ideal state shown in Figure 7. Because attenuation within the living body is greater, the signal strength (S / N ratio) of threshold X is reached at a depth of 8 cm. On the other hand, Figure 9 shows the relationship between signal strength and depth when attenuation within the living body is less than the ideal state. Because attenuation within the living body is less, the signal strength (S / N ratio) of threshold X is not reached until a depth of 20 cm. This makes it possible to display color information based on blood flow information on ultrasound images even in deep regions.

[0049] Taking these factors into consideration, in the ultrasound diagnostic device 100 according to this embodiment, the calculation function 168 of the processing circuitry 160 calculates the S / N ratio based on the virtual ultrasound image, and then calculates the depth limit at which color information based on blood flow information is displayed based on this calculated S / N ratio. That is, the calculation function 168 calculates the signal level of the reflected wave signal reflected within the living body based on the change in brightness within the virtual ultrasound image. Generally, in an ultrasound image, the lower the brightness, the weaker the signal strength of the reflected wave signal. Therefore, the signal level of the received reflected wave signal can be calculated based on the change in brightness within a predetermined range in the depth direction.

[0050] The noise is specified as a white noise level based on the diameter of the ultrasonic probe 10 that transmits the ultrasonic signal of the second condition into the living body. For example, a correspondence table between the diameter of the ultrasonic probe 10 used in this ultrasonic diagnostic device 100 and its white noise level may be stored in the memory circuitry 180, and the calculation function 168 may read this correspondence table to specify the white noise level. The diameter of the ultrasonic probe 10 connected to the ultrasonic diagnostic device 100 may be input by the user via the input interface 140, or the ultrasonic diagnostic device 100 may automatically detect the type of ultrasonic probe 10 connected to the ultrasonic diagnostic device 100 and specify its diameter.

[0051] The white noise level is determined based on the diameter of the ultrasonic probe 10 because there is a close relationship between the two. That is, the larger the diameter of the ultrasonic probe 10, the larger the white noise level. On the other hand, considering the strength of the signal that can be received, the larger the diameter of the ultrasonic probe 10, the larger the signal strength. For this reason, in this embodiment, the white noise level is calculated based on the size of the contact surface of the ultrasonic probe 10, that is, the diameter.

[0052] Then, the calculation function 168 of the processing circuit 160 calculates the ratio between the acquired signal level and the white noise level as the S / N ratio, and determines whether or not this calculated S / N ratio is smaller than the threshold value X. In other words, a region with an S / N ratio smaller than the threshold value X is determined to be a deep region where color information based on blood flow information cannot be displayed.

[0053] 4, the ultrasound diagnostic device 100 acquires an ultrasound image (step S14). In this embodiment, the process of acquiring this ultrasound image is realized by the first acquisition function 162 in the processing circuitry 160 of the ultrasound diagnostic device 100.

[0054] Specifically, the first acquisition function 162 transmits ultrasound into the living body under conditions (first conditions) for generating a B-mode image, and generates an ultrasound image as a B-mode image based on the reflected wave signal. Note that if this ultrasound image as a B-mode image has already been acquired by another process, step S14 in this color mode display process can be omitted.

[0055] 4, the ultrasound diagnostic device 100 acquires blood flow information in the ultrasound image acquired in step S14 (step S16). In this embodiment, the process of acquiring this blood flow information is realized by the second acquisition function 164 in the processing circuitry 160 of the ultrasound diagnostic device 100.

[0056] Specifically, the second acquisition function 164 transmits ultrasound waves into the subject's body under second conditions for acquiring blood flow information, and acquires the blood flow information based on the reflected wave signals. That is, the reflected wave signals are analyzed based on the Doppler method, which utilizes the Doppler shift in the reflected wave signals, to calculate the blood flow direction and blood flow velocity in the target region. Then, the second acquisition function 164 calculates, for example, the average velocity, average variance, and average power value of the blood flow based on the calculated blood flow direction and blood flow velocity. In this embodiment, information related to the blood flow, such as the blood flow direction and blood flow velocity, as well as the average velocity, average variance, and average power value of the blood flow, is referred to as blood flow information.

[0057] 4, the ultrasound diagnostic device 100 generates color information based on the blood flow information acquired in step S16 (step S18). In this embodiment, the process of generating this color information is also realized by the second acquisition function 164 in the processing circuitry 160 of the ultrasound diagnostic device 100.

[0058] Specifically, the second acquisition function 164 generates color information based on the blood flow by representing the blood flow approaching the ultrasound probe 10 in red and the blood flow moving away from the ultrasound probe 10 in blue, and by representing the blood flow velocity with changes in hue and brightness. It is also possible to represent the mean variance and mean power values ​​of the blood flow as color information using green. These can be changed or combined as appropriate depending on the area where the blood flow is to be measured and the user's settings.

[0059] 4, the ultrasound diagnostic device 100 displays the color information generated in step S18 superimposed on the ultrasound image acquired in step S14 (step S20). In this embodiment, the process of superimposing the color information on the ultrasound image is realized by the superimposed display function 166 in the processing circuitry 160 of the ultrasound diagnostic device 100.

[0060] Specifically, the superimposed display function 166 superimposes color information based on the blood flow information generated in step S18 onto the ultrasound image, which is the B-mode image acquired in step S14, and displays the superimposed image on the display 150. As a result, an ultrasound image including blood flow information expressed by color information, such as that shown in FIG. 2, is displayed on the display 150.

[0061] 4, the ultrasound diagnostic device 100 notifies the user of the depth limit at which color information based on the blood flow information is displayed, calculated in step S12 (step S22). In this embodiment, the process of notifying the user of the depth limit at which this color information is displayed is realized by the user notification function 170 in the processing circuitry 160 of the ultrasound diagnostic device 100.

[0062] Specifically, the user notification function 170 notifies the user of the depth limit at which color information based on blood flow information calculated by the calculation function 168 is displayed, using various methods. That is, while an ultrasound image is being displayed in color mode, the user is notified of the depth limit at which color information is displayed by imposing some kind of restriction or by displaying some kind of additional information. In this embodiment, after notifying the user in step S22, the ultrasound diagnostic apparatus 100 returns to the above-described step S16 and repeats the process from step S16.

[0063] FIG. 10 is a diagram showing an example in which the user is notified of the depth limit at which color information is displayed by restricting the movement of a region of interest (ROI) identification display 200 that identifies a region of interest within an ultrasound image. In this embodiment, for example, via operation of the input interface 140, the user can move the region of interest (ROI) identification display 200, which is a display that identifies a region of interest in the user, on the ultrasound image displayed on the display 150. The ultrasound diagnostic device 100 according to this embodiment is configured to acquire blood flow information for a region within the ultrasound image identified by the region of interest identification display 200 in step S16. This shortens the time required for acquiring blood flow information in the ultrasound diagnostic device 100 and improves response characteristics related to the blood flow information. The function of displaying the region of interest identification display 200 so that it can be moved by user operation is realized by a region of interest movement function 172 in the processing circuitry 160.

[0064] The above-described user notification function 170 limits movement of the region of interest identification display 200 by the region of interest movement function 172 in accordance with the depth limit calculated by the calculation function 168 at which color information based on blood flow information is displayed. In the example of FIG. 10 , color information based on blood flow information can be displayed in shallow areas of the ultrasound image, but is too deep to be displayed in deep areas. Therefore, the user notification function 170 limits the user's movement of the region of interest identification display 200 when the bottom edge of the region of interest identification display 200 reaches the depth limit at which color information based on blood flow information is displayed. In other words, the user cannot move the region of interest identification display 200 any further toward the depth of the ultrasound image.

[0065] In this way, by displaying the ultrasound image in color mode and restricting the user's movement of region of interest identification display 200, the user can know that color information based on blood flow information will not be displayed in regions deeper than this. In other words, this processing by user notification function 170 can notify the user that the limit to which region of interest identification display 200 can be moved in the deep direction is the depth limit at which color information based on blood flow information is displayed.

[0066] 11 is a diagram showing an example of displaying a marker 202 together with an ultrasound image according to the depth limit at which color information based on blood flow information is displayed, as another example of notification to a user by the user notification function 170. Specifically, the user notification function 170 displays the marker 202 together with the ultrasound image displayed on the display 150 according to the depth limit at which color information based on blood flow information is displayed, calculated by the calculation function 168.

[0067] In the example of Fig. 11, the marker 202 has a rod-like shape extending from a shallow portion to a deep portion of the ultrasound image. The bottom end of the marker 202 corresponds to the depth limit at which color information based on blood flow information is displayed. In other words, the user can know that color information based on blood flow information can be displayed up to the depth at which the marker 202 is displayed, but that color information based on blood flow information cannot be displayed at depths at which the marker 202 is not displayed. In other words, this processing by the user notification function 170 can notify the user that the bottom end of the marker 202 is the depth limit at which color information based on blood flow information is displayed.

[0068] 11, the marker 202 has a role of indicating an area where color information based on blood flow information is displayed, but the role of the marker 202 may be reversed. That is, the marker 202 may have a role of indicating an area where color information based on blood flow information is not displayed.

[0069] FIG. 12 is a diagram showing another example of a notification to the user by the user notification function 170, informing the user to change the frequency of ultrasound transmitted into the subject's body to acquire blood flow information. This is an example of a countermeasure being presented to the user when the user notification function 170 restricts the movement of the region of interest identification display 200 in the deeper direction shown in FIG. 10 described above. That is, in the color mode ultrasound image shown in FIG. 10, if the user attempts to move the region of interest identification display 200 in the deeper direction but reaches the depth limit at which color information based on blood flow information is displayed, the movement is restricted. Then, at the same time as the movement is restricted, a message appears on the display 150 saying, "Please lower the frequency of ultrasound waves to acquire blood flow information."

[0070] The notification to the user that the ultrasound frequency will be changed is displayed along with the ultrasound image while restricting the user from moving the region of interest identification display 200. The notification to the user that the ultrasound frequency will be changed may be displayed inside the ultrasound image and superimposed on the ultrasound image, or may be displayed outside the ultrasound image without superimposing on the ultrasound image.

[0071] As described above, the depth that ultrasound can reach within a living body varies depending on its frequency. Specifically, lower-frequency ultrasound can reach deeper regions within a living body than higher-frequency ultrasound. Therefore, by lowering the frequency of the second condition for acquiring blood flow information, the ultrasound may be able to reach deeper regions within the living body. Therefore, in the example of FIG. 12, by prompting the user to lower the frequency of the ultrasound used to acquire blood flow information, the user can be informed that color information based on the blood flow information may be obtained from deeper regions.

[0072] When the user wants to lower the frequency of the ultrasound waves used to obtain blood flow information, for example, the user operates input interface 140 to temporarily terminate the color mode display process shown in FIG. 4 and change the frequency of the second condition in ultrasound diagnostic device 100. Then, this color mode display process is executed again using the newly set frequency of the second condition. As a result, a virtual ultrasound image is acquired using ultrasound waves of the newly set frequency of the second condition (step S10), and the limit of the depth at which color information is displayed is calculated (step S12). On the other hand, if the user does not want to lower the frequency of the ultrasound waves, the process returns to step S16, and this color mode display process continues to be executed.

[0073] The notification to the user by the user notification function 170 that the ultrasound frequency should be changed is not limited to text information as shown in Fig. 12, and may be audio information. There are various possible conditions for the user notification function 170 to notify the user that the ultrasound frequency should be changed. For example, this notification may be made when the user touches with a finger or clicks with a mouse an area of ​​the ultrasound image displayed on the display 150 where color information based on blood flow information is not displayed.

[0074] As described above, the ultrasound diagnostic device 100 according to this embodiment and the ultrasound diagnostic system 1 including this ultrasound diagnostic device 100 can calculate in advance the depth limit at which color information based on blood flow information can be displayed in a color mode ultrasound image by transmitting ultrasound into the subject's body under the condition (second condition) for acquiring blood flow information. Therefore, the depth limit at which the calculated color information based on blood flow information can be displayed can be notified to the user as needed. As a result, the user can clearly understand why color information is not displayed even though blood vessels are present in the ultrasound image. This eliminates the user's anxiety caused by not displaying color information based on blood flow information and prevents the user from erroneously determining that blood flow is not present.

[0075] Although several embodiments have been described above, these embodiments are presented only as examples and are not intended to limit the scope of the invention. The novel apparatus and method described herein may be embodied in various other forms. Furthermore, various omissions, substitutions, and modifications may be made to the forms of the apparatus and method described herein without departing from the spirit of the invention. The appended claims and their equivalents are intended to cover such forms and modifications that fall within the scope and spirit of the invention. [Explanation of symbols]

[0076] 1...ultrasound diagnostic system, 10...ultrasound probe, 20...external device, 100...ultrasound diagnostic device, 110...ultrasound transmission circuit, 112...ultrasound reception circuit, 120...signal processing circuit, 130...communication interface, 140...input interface, 150...display, 160...processing circuit, 162...first acquisition function, 164...second acquisition function, 166...overlapping display function, 168...calculation function, 170...user notification function, 172...region of interest movement function, 180...memory circuit, 200...region of interest identification display, 202...marker

Claims

1. a first acquisition unit that acquires an in-vivo ultrasound image of a subject; a second acquisition unit that acquires blood flow information in the ultrasound image acquired by the first acquisition unit and generates color information based on the acquired blood flow information; an overlay display unit that displays the generated color information by overlaying it on the ultrasound image acquired by the first acquisition unit; a calculation unit that calculates a depth limit at which color information is displayed on the superimposed display unit based on signal attenuation occurring in the living body; An ultrasound diagnostic device comprising:

2. the first acquisition unit transmits ultrasonic waves into a living body under a first condition to acquire an ultrasonic image of the living body of the subject; the second acquisition unit transmits ultrasound into the living body under a second condition different from the first condition in order to acquire the blood flow information; 2. The ultrasound diagnostic device according to claim 1, wherein the calculation unit acquires a virtual ultrasound image by transmitting ultrasound into the subject's living body under the second condition, and calculates, based on the acquired virtual ultrasound image, a depth limit at which color information based on the blood flow information is displayed on the superimposition display unit.

3. The ultrasound diagnostic device according to claim 2 , wherein the calculation unit calculates a limit of a depth at which color information based on the blood flow information is displayed on the superimposed display unit based on a change in brightness within the acquired virtual ultrasound image.

4. The calculation unit calculating a signal level of a reflected wave signal reflected within a living body based on a change in brightness within the virtual ultrasound image; Specifying a white noise level based on the diameter of the ultrasonic probe that transmits the ultrasonic waves of the second condition; a ratio of the signal level to the white noise level is calculated as an S / N ratio, and a region in the virtual ultrasound image having an S / N ratio smaller than a predetermined threshold is determined to be a region deeper than the limit of depth at which color information is displayed on the superimposed display unit. The ultrasonic diagnostic apparatus according to claim 3 .

5. 5. The ultrasonic diagnostic apparatus according to claim 2, wherein the frequency of the ultrasonic waves of the second condition is higher than the frequency of the ultrasonic waves of the first condition.

6. 6. The ultrasound diagnostic apparatus according to claim 1, further comprising a user notification unit that notifies a user of a depth limit calculated by the calculation unit at which color information based on the blood flow information is displayed on the superimposition display unit.

7. a region of interest moving unit that displays a region of interest identification display that identifies a region of interest of a user in the ultrasound image displayed on the overlapping display unit in a movable manner by a user operation, 7. The ultrasound diagnostic apparatus according to claim 6, wherein the user notification unit limits movement of the region of interest specified display by the region of interest moving unit in accordance with a depth limit calculated by the calculation unit at which color information based on the blood flow information is displayed on the overlap display unit.

8. The ultrasound diagnostic apparatus according to claim 7 , wherein the second acquisition unit acquires blood flow information for a region in the ultrasound image identified by the region of interest identification display.

9. 7. The ultrasound diagnostic device according to claim 6, wherein the user notification unit displays a marker together with the ultrasound image displayed by the superimposition display unit, in accordance with a depth limit calculated by the calculation unit at which color information based on the blood flow information is displayed on the superimposition display unit.

10. 7. The ultrasound diagnostic apparatus of claim 6, wherein the user notification unit notifies the user to change a frequency of the ultrasound transmitted into the living body of the subject by the second acquisition unit in order to acquire blood flow information within the ultrasound image acquired by the first acquisition unit.

11. The ultrasound diagnostic apparatus according to claim 10 , wherein the user notification unit notifies the user to change the frequency of the ultrasound waves transmitted by the second acquisition unit into the living body of the subject to a lower frequency.

12. acquiring an in vivo ultrasound image of a subject; acquiring blood flow information in the acquired ultrasound image, and generating color information based on the acquired blood flow information; a step of superimposing the generated color information on an ultrasound image and displaying the same on a display screen; calculating a depth limit at which color information is displayed on the display screen based on signal attenuation occurring in a living body; A method for controlling an ultrasonic diagnostic apparatus comprising:

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