Ultrasound diagnostic device, ultrasound diagnostic method, and ultrasound diagnostic program

Abstract

It is easy to determine whether the detection target exists outside the plane. [Solution] An ultrasound diagnostic apparatus according to an embodiment includes an acquisition unit, a calculation unit, and a display control unit. The acquisition unit acquires a first echo signal based on a first ultrasound beam and acquires a second echo signal based on a second ultrasound beam that at least partially overlaps with the region of the first ultrasound beam but has a different beam region in the elevation direction. The calculation unit calculates a differential signal that is the difference between the first echo signal and the second echo signal. The display control unit displays a differential image based on the differential signal.

Description

[Technical Field]

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

[0002] In needle biopsy and RFA (Radio Frequency Ablation) treatment, the positional relationship between the target and the needle tip is often confirmed under ultrasound guidance. In this case, there is a method to highlight the needle part depicted on the ultrasound image. Generally, when performing the above-mentioned tasks, the ultrasound images displayed in real time are two-dimensional cross-sectional images, so even if the needle tip appears to be positioned within the target, it may actually be displaced behind or in front of the target. In this case, the displaced needle tip, which is not visualized in the ultrasound image, cannot be highlighted, making it difficult for the operator to grasp the displacement of the needle tip. Furthermore, similar difficulties arise not only with the tip of a puncture needle, but also with other detection targets that need to be confirmed under ultrasound guidance, such as catheters and stents. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6176839 Summary of the Invention [Problem to be solved by the invention]

[0004] One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to easily determine whether a detection target exists outside the plane. 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]

[0005] The ultrasound diagnostic apparatus according to this embodiment includes an acquisition unit, a calculation unit, and a display control unit. The acquisition unit acquires first echo signals based on a first ultrasound beam and acquires second echo signals based on a second ultrasound beam that at least partially overlaps with the region of the first ultrasound beam and has a different beam region in the elevation direction. The calculation unit calculates a difference signal that is the difference between the first echo signal and the second echo signal. The display control unit displays a difference image based on the difference signal. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a block diagram showing an example of the configuration of an ultrasonic diagnostic apparatus according to this embodiment. [Figure 2] FIG. 2 is a flowchart showing an example of the operation of the ultrasound diagnostic apparatus according to the first embodiment. [Figure 3] FIG. 3 is a diagram showing a first example of generation of an ultrasonic beam. [Figure 4] FIG. 4 is a diagram showing beam settings for a detection target according to the first generation example. [Figure 5] FIG. 5 is a diagram showing a display example of an ultrasound image and a superimposed image in the first generation example. [Figure 6] FIG. 6 is a diagram showing a second example of generation of an ultrasonic beam. [Figure 7] FIG. 7 is a flowchart showing an example of the operation of the ultrasound diagnostic apparatus according to the second embodiment. [Figure 8] FIG. 8 is a diagram illustrating a third example of generation of an ultrasonic beam. [Figure 9] FIG. 9 is a diagram illustrating a fourth example of generation of an ultrasonic beam. [Figure 10] FIG. 10 is a diagram showing beam settings for a detection target according to the fourth generation example. [Figure 11] FIG. 11 is a diagram showing a display example of an ultrasound image and a superimposed image in the fourth generation example. [Figure 12]FIG. 12 is a diagram illustrating a fifth example of generation of an ultrasonic beam. [Figure 13] FIG. 13 is a diagram showing beam settings for a detection target according to the fifth generation example. [Figure 14] FIG. 14 is a diagram showing a display example of an ultrasound image and a superimposed image in the fifth generation example. [Figure 15] FIG. 15 is a diagram showing a display example of an ultrasound image and a superimposed image when a ROI is targeted. DETAILED DESCRIPTION OF THE INVENTION

[0007] The ultrasound diagnostic device, ultrasound diagnostic method, and ultrasound diagnostic program according to the present embodiment will be described below with reference to the drawings. In the following embodiments, parts with the same reference numerals perform similar operations, and redundant description will be omitted as appropriate.

[0008] (First embodiment) Fig. 1 is a diagram showing an example of the configuration of an ultrasound diagnostic apparatus according to this embodiment. The ultrasound diagnostic apparatus 1 in Fig. 1 includes an apparatus main body 100 and an ultrasound probe 101. The apparatus main body 100 is connected to an input device 102 and an output device 103. The apparatus main body 100 is also connected to an external device 104 via a network NW. The external device 104 is, for example, a server equipped with a PACS (Picture Archiving and Communication Systems) and a workstation capable of executing post-processing.

[0009] The ultrasonic probe 101 performs an ultrasonic scan of a scan region in a living body P, which is a subject, under control of the device main body 100, for example. The ultrasonic probe 101 includes, for example, an acoustic lens, one or more matching layers, multiple transducers (piezoelectric elements), and a backing material. The acoustic lens is made of, for example, silicone rubber and focuses an ultrasonic beam. The one or more matching layers perform impedance matching between the multiple transducers and the living body. The backing material prevents ultrasonic waves from propagating backward in the radiation direction from the multiple transducers. The ultrasonic probe 101 is, for example, a linear probe or a convex probe. The ultrasonic probe 101 is detachably connected to the device main body 100. The ultrasonic probe 101 may be provided with buttons that are pressed for offset processing and operations to freeze an ultrasound image (freeze operation).

[0010] The multiple transducers generate ultrasonic waves based on drive signals supplied from an ultrasonic transmission circuit 110 (described later) included in the device main body 100. This causes ultrasonic waves to be transmitted from the ultrasonic probe 101 to the living body P. When ultrasonic waves are transmitted from the ultrasonic probe 101 to the living body P, the transmitted ultrasonic waves are reflected successively by discontinuous surfaces of acoustic impedance in the body tissue of the living body P and received as echo signals by the multiple piezoelectric transducers. The amplitude of the received echo signals depends on the difference in acoustic impedance at the discontinuous surfaces from which the ultrasonic waves are reflected. Furthermore, when a transmitted ultrasonic pulse is reflected by a moving surface such as a blood flow or a heart wall, the echo signal undergoes a frequency shift due to the Doppler effect, depending on the velocity component of the moving object in the direction of ultrasonic transmission. The ultrasonic probe 101 receives the echo signals from the living body P and converts them into electrical signals.

[0011] 1 illustrates an example of the connection relationship between one ultrasonic probe 101 and the device main body 100. However, it is possible to connect multiple ultrasonic probes 101 to the device main body 100. Which of the multiple connected ultrasonic probes 101 is to be used for ultrasonic scanning can be arbitrarily selected, for example, by using a software button on a touch panel, which will be described later.

[0012] The device main body 100 is a device that generates an ultrasound image based on an echo signal (also referred to as an echo signal) received by an ultrasound probe 101. The device main body 100 includes an ultrasound transmission circuit 110, an ultrasound reception circuit 120, an internal storage circuit 130, an image memory 140, an input interface 150, an output interface 160, a communication interface 170, and a processing circuit 180.

[0013] The ultrasonic transmission circuit 110 is a processor that supplies a drive signal to the ultrasonic probe 101. The ultrasonic transmission circuit 110 is realized by, for example, a trigger generation circuit, a delay circuit, and a pulser circuit. The trigger generation circuit repeatedly generates rate pulses at a predetermined rate frequency to form transmitted ultrasonic waves. The delay circuit provides each rate pulse generated by the trigger generation circuit with a delay time for each of the multiple piezoelectric transducers required to focus the ultrasonic waves generated from the ultrasonic probe into a beam and determine the transmission directivity. The pulser circuit applies drive signals (drive pulses) to the multiple ultrasonic transducers provided in the ultrasonic probe 101 at a timing based on the rate pulse. By changing the delay time provided to each rate pulse using the delay circuit, the transmission direction from the surfaces of the multiple piezoelectric transducers can be freely adjusted.

[0014] Furthermore, the ultrasonic transmission circuit 110 can arbitrarily change the output intensity of the ultrasonic waves using a drive signal. By increasing the output intensity, the ultrasonic diagnostic device can acquire echo signals with a high signal-to-noise ratio (SNR) during reception.

[0015] Generally, when ultrasound propagates through a living body P, the strength of the ultrasound vibration (also called acoustic power), which corresponds to the output intensity, attenuates. The attenuation of acoustic power occurs due to absorption, scattering, reflection, and the like. The degree of reduction in acoustic power depends on the frequency of the ultrasound and the distance in the direction of ultrasound radiation. For example, the degree of attenuation increases as the frequency of the ultrasound increases. Furthermore, the longer the distance in the direction of ultrasound radiation, the greater the degree of attenuation.

[0016] The ultrasonic receiving circuit 120 is a processor that performs various processes on the echo signals received by the ultrasonic probe 101 to generate received signals. The ultrasonic receiving circuit 120 generates received signals for the echo signals of the ultrasonic waves acquired by the ultrasonic probe 101. Specifically, the ultrasonic receiving circuit 120 is realized by, for example, a preamplifier, an A / D converter, a demodulator, and a beamformer (adder). The preamplifier amplifies the echo signals received by the ultrasonic probe 101 for each channel and performs gain correction processing. The A / D converter converts the gain-corrected echo signals into digital signals. The demodulator demodulates the digital signals. For example, the beamformer applies a delay time required to determine the reception directivity to the demodulated digital signals and adds up multiple digital signals with the applied delay time. The addition processing of the beamformer generates a received signal in which the reflection components from the direction corresponding to the reception directivity are emphasized. The received signal may also be called an IQ signal. Furthermore, the ultrasonic wave receiving circuit 120 may store the received signal (IQ signal) in an internal storage circuit 130 (described later), or may output the received signal to the external device 104 via the communication interface 170.

[0017] The internal storage circuit 130 includes a processor-readable storage medium, such as a magnetic storage medium, an optical storage medium, or a semiconductor memory. The internal storage circuit 130 stores programs and various data for transmitting and receiving ultrasound waves. The programs and various data may be pre-stored in the internal storage circuit 130. Alternatively, the programs and various data may be stored in a non-transitory storage medium, distributed, read from the non-transitory storage medium, and installed in the internal storage circuit 130. The internal storage circuit 130 also stores B-mode image data, contrast image data, and image data related to blood flow images generated by the processing circuit 180 in accordance with operations input via the input interface 150. The internal storage circuit 130 can also transfer the stored image data to an external device 104 or the like via the communication interface 170. The internal storage circuit 130 may store reception signals (IQ signals) generated by the ultrasound reception circuit 120, or may transfer the reception signals to an external device 104 or the like via the communication interface 170.

[0018] The internal storage circuit 130 may be a drive device that reads and writes various information from and to a portable storage medium such as a CD drive, a DVD drive, or a flash memory. The internal storage circuit 130 can also write stored data to the portable storage medium and store the data in the external device 104 via the portable storage medium.

[0019] The image memory 140 includes a processor-readable storage medium, such as a magnetic storage medium, an optical storage medium, or a semiconductor memory. The image memory 140 stores image data corresponding to a plurality of frames immediately before a freeze operation, which are input via the input interface 150. The image data stored in the image memory 140 is displayed continuously (cine display), for example.

[0020] The internal storage circuit 130 and the image memory 140 do not necessarily have to be realized by independent storage devices. The internal storage circuit 130 and the image memory 140 may be realized by a single storage device. Furthermore, the internal storage circuit 130 and the image memory 140 may each be realized by multiple storage devices.

[0021] The input interface 150 accepts various instructions from an operator via the input device 102. Examples of the input device 102 include a mouse, a keyboard, a panel switch, a slider switch, a trackball, a rotary encoder, an operation panel, and a touch command screen (TCS). The input interface 150 is connected to the processing circuitry 180 via a bus, for example, converts operation instructions input by the operator into electrical signals, and outputs the electrical signals to the processing circuitry 180. Note that the input interface 150 is not limited to those connected to physical operation components such as a mouse and a keyboard. For example, a circuit that receives electrical signals corresponding to operation instructions input from an external input device provided separately from the ultrasound diagnostic apparatus 1 and outputs the electrical signals to the processing circuitry 180 is also included as an example of an input interface.

[0022] The output interface 160 is an interface for outputting, for example, an electrical signal from the processing circuit 180 to the output device 103. The output device 103 is any display such as a liquid crystal display, an organic EL display, an LED display, a plasma display, or a CRT display. The output device 103 may be a touch panel display that also serves as the input device 102. In addition to the display, the output device 103 may further include a speaker that outputs audio. The output interface 160 is connected to the processing circuit 180 via, for example, a bus, and outputs the electrical signal from the processing circuit 180 to the output device 103.

[0023] The communication interface 170 is connected to the external device 104 via, for example, a network NW, and is an interface for performing data communication with the external device 104 .

[0024] The processing circuitry 180 is, for example, a processor that functions as the core of the ultrasound diagnostic apparatus 1. The processing circuitry 180 executes a program stored in the internal storage circuitry 130 to realize a function corresponding to the program. The processing circuitry 180 includes, for example, a B-mode processing function 181, a Doppler processing function 182, an image generation function 183, an acquisition function 184, a speckle suppression function 185, a difference calculation function 186, a display control function 187, a detection function 188, and a system control function 189.

[0025] The B-mode processing function 181 is a function that generates B-mode data based on the reception signal received from the ultrasound reception circuit 120. In the B-mode processing function 181, the processing circuit 180 performs, for example, envelope detection processing and logarithmic compression processing on the reception signal received from the ultrasound reception circuit 120, and generates data (B-mode data) in which the signal intensity is expressed as brightness of luminance. The generated B-mode data is stored in a RAW data memory (not shown) as B-mode RAW data on a two-dimensional ultrasound scan line (raster).

[0026] The Doppler processing function 182 is a function that generates data (Doppler information) that extracts motion information based on the Doppler effect of a moving object within a region of interest (ROI) set in the scan area by performing frequency analysis on the received signal received from the ultrasound receiving circuit 120. The generated Doppler information is stored in a RAW data memory (not shown) as Doppler RAW data (also referred to as Doppler data) on a two-dimensional ultrasound scan line.

[0027] Specifically, the processing circuitry 180 uses the Doppler processing function 182 to estimate, for example, the average velocity, average variance, average power, etc., as motion information of a moving object at each of a plurality of sample points, and generates Doppler data indicating the estimated motion information. The moving object may be, for example, blood flow, tissue such as a heart wall, or a contrast agent. The processing circuitry 180 uses the Doppler processing function 182 to estimate, for each of a plurality of sample points, the average velocity of blood flow, the variance of blood flow velocity, the power value of blood flow signals, etc., as motion information of blood flow (blood flow information), and generates Doppler data indicating the estimated blood flow information.

[0028] Furthermore, the processing circuitry 180 can execute a color Doppler method, also known as a color flow mapping (CFM) method, using the Doppler processing function 182. In the CFM method, ultrasonic waves are transmitted and received multiple times along multiple scan lines. The CFM method, for example, applies an MTI (Moving Target Indicator) filter to a data sequence at the same position to suppress signals (clutter signals) originating from stationary or slow-moving tissues and extract signals originating from blood flow. The CFM method then estimates blood flow information, such as blood flow velocity, blood flow dispersion, and blood flow power, using the extracted blood flow signals. The image generation function 183, described later, generates the distribution of the estimated blood flow information as, for example, two-dimensional color-displayed ultrasound image data (color Doppler image data). Hereinafter, the mode of the ultrasound diagnostic device using the color Doppler method is referred to as a blood flow image mode. Note that color display refers to displaying the distribution of blood flow information in accordance with a predetermined color code, and grayscale is also included in the color display.

[0029] There are various types of blood flow imaging modes depending on the desired clinical information. Generally, there is a blood flow velocity imaging mode that can visualize the direction and average velocity of blood flow, and a blood flow power imaging mode that can visualize the power of blood flow signals.

[0030] The velocity display blood flow imaging mode is a mode that displays colors corresponding to the Doppler shift frequency depending on the direction and average velocity of blood flow. For example, the velocity display blood flow imaging mode displays oncoming flow as reddish colors and receding flow as blued colors, and the difference in speed is displayed by the difference in hue. The velocity display blood flow imaging mode is also called color Doppler mode or color Doppler imaging (CDI) mode.

[0031] The power-display blood flow imaging mode is a mode in which the power of a blood flow signal is expressed, for example, by changes in reddish hue, color brightness (intensity), or saturation. The power-display blood flow imaging mode is also called a power Doppler (PD) mode. The power-display blood flow imaging mode may also be called a high-sensitivity blood flow imaging mode because it can depict blood flow with higher sensitivity than the velocity-display blood flow imaging mode.

[0032] The image generation function 183 is a function that generates B-mode image data based on data generated by the B-mode processing function 181. For example, in the image generation function 183, the processing circuitry 180 converts (scan converts) a scan line signal sequence of an ultrasound scan into a scan line signal sequence of a video format typified by a television or the like, and generates image data for display (display image data). Specifically, the processing circuitry 180 performs RAW-to-pixel conversion on the B-mode RAW data stored in the RAW data memory, for example, coordinate conversion according to the ultrasound scanning form of the ultrasound probe 101, thereby generating two-dimensional B-mode image data (also referred to as ultrasound image data) composed of pixels. In other words, the processing circuitry 180 generates a plurality of ultrasound images (medical images) corresponding to a plurality of consecutive frames by transmitting and receiving ultrasound waves using the image generation function 183.

[0033] The image generation function 183 also has a function of generating Doppler image data based on the data generated by the Doppler processing function 182. For example, the image generation function 183 generates Doppler image data in which blood flow information is visualized by performing RAW-to-pixel conversion on the Doppler RAW data stored in the RAW data memory. The Doppler image data is mean velocity image data, variance image data, power image data, or image data combining these. The processing circuitry 180 generates, as the Doppler image data, color Doppler image data in which blood flow information is displayed in color, and Doppler image data in which one piece of blood flow information is displayed in a grayscale wave shape. The color Doppler image data is generated when the aforementioned blood flow imaging mode is executed.

[0034] The acquisition function 184 acquires a first echo signal based on a first ultrasonic beam and acquires a second echo signal based on a second ultrasonic beam that at least partially overlaps with the area of ​​the first ultrasonic beam and has a different beam area in the elevation direction. The speckle suppression function 185 performs speckle suppression processing on the first echo signal and the second echo signal. The difference calculation function 186 calculates a difference signal that is the difference between the first echo signal and the second echo signal.

[0035] The display control function 187 displays a difference image based on the difference signal. Furthermore, the display control function 187 is a function that causes an image based on various ultrasound image data generated by the image generation function 183 to be displayed on a display serving as the output device 103. Specifically, for example, the display control function 187 causes the processing circuitry 180 to control the display of an image based on B-mode image data, Doppler image data, or image data including both generated by the image generation function 183 on a display.

[0036] More specifically, the display control function 187 causes the processing circuitry 180 to convert (scan convert) a scan line signal sequence of an ultrasound scan into a scan line signal sequence of a video format, such as that of a television, to generate display image data. The processing circuitry 180 may also perform various processes on the display image data, such as dynamic range, brightness, contrast, and gamma curve correction, as well as RGB conversion. The processing circuitry 180 may also add supplementary information, such as text information of various parameters, scales, and body marks, to the display image data. The processing circuitry 180 may also generate a user interface (GUI: Graphical User Interface) for an operator to input various instructions via an input device, and display the GUI on a display.

[0037] The detection function 188 detects whether or not the detection target is depicted in the difference image. Furthermore, if the detection target is depicted in the difference image, the detection function 188 determines that at least a portion of the detection target is located outside the plane of the desired cross-sectional image. Note that in this embodiment, the detection target is assumed to be a puncture needle, particularly the tip of the puncture needle, but is not limited to this and can be any object whose position is to be confirmed under echo guidance, such as a catheter or a stent. The system control function 189 is a function that controls the overall operation of the ultrasound diagnostic apparatus 1 .

[0038] Next, an example of the operation of the ultrasonic diagnostic apparatus 1 according to the first embodiment will be described with reference to the flowchart of FIG.

[0039] In step SA1, the processing circuitry 180 collects a first echo signal based on the first ultrasonic beam using the collection function 184. Specifically, the ultrasonic transmission circuitry 110, the ultrasonic probe 101, and the ultrasonic reception circuitry 120 are controlled to transmit an ultrasonic beam set to a desired beam thickness for imaging a region of interest (ROI) toward the living body P, and the first echo signal based on the first ultrasonic beam is collected.

[0040] In step SA2, the processing circuitry 180 sets the area of ​​the beam in the elevation direction to be different from that of the first ultrasonic beam by the collection function 184. Specifically, the ultrasonic transmission circuitry 110, the ultrasonic probe 101, and the ultrasonic reception circuitry 120 are controlled, and the area of ​​the second ultrasonic beam, which will be described later, is set.

[0041] In step SA3, the processing circuit 180 collects second echo signals based on the second ultrasonic beam based on the conditions changed in step SA2 using the collection function 184. Specifically, similar to step SA1, the ultrasonic transmission circuit 110, the ultrasonic probe 101, and the ultrasonic reception circuit 120 are controlled to collect second echo signals based on the second ultrasonic beam.

[0042] In step SA4, the processing circuitry 180 executes speckle suppression processing on the first echo signal and the second echo signal using the speckle suppression function 185. This is because, when the spatial region of the beam in the elevation direction changes, the speckle pattern also fluctuates. Depending on the speckle state, there is a possibility that parts other than the detection target will have a high signal after differential processing, which may lead to erroneous detection. Therefore, speckle suppression processing is performed to minimize the high signal intensity of parts other than the detection target. Specifically, the speckle suppression processing may be performed by, for example, filtering such as applying a spatial low-pass filter, averaging multiple echo signals, or a combination of these.

[0043] In step SA5, the processing circuitry 180 calculates the difference between the first echo signal and the second echo signal after the speckle suppression process using the difference calculation function 186. The calculation of the difference may be performed by subtracting the first echo signal from the second echo signal, or by subtracting the second echo signal from the first echo signal.

[0044] In step SA6, the processing circuit 180 executes threshold processing using the difference calculation function 186 to extract signal values ​​in the difference signal that are equal to or greater than a threshold. The threshold processing is a process for excluding non-detection targets. In other words, since it is desired to detect detection targets that are not present in the spatial domain of the first ultrasonic beam but are present in the spatial domain of the second ultrasonic beam, signal values ​​that produce negative values ​​when the first echo signal is subtracted from the second echo signal can be said to be non-detection targets, and therefore threshold processing can be executed on the difference signal. Note that when the second echo signal is subtracted from the first echo signal, signal values ​​that produce positive values ​​when the subtraction is performed can be determined to be non-detection targets.

[0045] In step SA7, the display control function 187 causes the processing circuit 180 to generate a difference image based on the difference signal, and the display control function causes the processing circuit 180 to display the difference image on an external display or the like.

[0046] In step SA8, the display control function 187 causes the processing circuitry 180 to superimpose and display a difference image on the first ultrasound image based on the first echo signal (hereinafter also referred to as a superimposed image). When superimposing and displaying, the difference image and the first ultrasound image may be displayed in different colors. Alternatively, the difference image may be displayed independently.

[0047] In step SA9, the processing circuitry 180 determines whether or not the detection target exists outside the plane of the desired cross-sectional image based on the differential signal using the detection function 188. For example, if the differential signal does not contain a signal value equal to or greater than the threshold, it is considered that the detection target is not depicted in the differential signal, and therefore it can be determined that the detection target does not exist outside the plane of the desired cross-sectional image, that is, that the detection target exists within the cross-sectional image.

[0048] In step SA10, the processing circuit 180 may display, for example, a message indicating that the detection target is out of plane together with the difference image or the superimposed image on a display by using the display control function 187. Also, a voice or alert sound indicating that the detection target is out of plane may be output from a speaker.

[0049] The differential image may be generated without performing the speckle suppression process in step SA4 and the threshold process in step SA6. Furthermore, steps SA7 and SA8 and steps SA9 and SA10 may be processed independently or consecutively. That is, steps SA7 and SA8 may be processed without steps SA9 and SA10, and the superimposed image may simply be displayed on the display. Alternatively, steps SA9 and SA10 may be processed without steps SA7 and SA8, and a message indicating whether the detection target is located outside the plane may be displayed while an ultrasound image based on the first echo signal is displayed on the display.

[0050] When steps SA7 to SA10 are processed consecutively, the determination process in step SA9 may be performed based on the difference image. Specifically, the processing circuit 180 determines that the detection target exists outside the plane if there is a portion in the difference image having a signal value equal to or greater than a threshold value so as to be continuous with the desired cross-sectional image in the difference image using the detection function 188. On the other hand, if there is no portion in the difference image having a signal value equal to or greater than the threshold value, it may determine that the detection target does not exist outside the plane.

[0051] Next, a first example of generating an ultrasonic beam according to the first embodiment will be described with reference to FIG. The first generation example shown in FIG. 3 illustrates an example in which the frequencies of the ultrasonic beams transmitted from or received by the ultrasonic probe 101 are different. A first ultrasonic beam 301 is transmitted or received using a first frequency that results in a desired beam thickness in the elevation direction, and a first echo signal is acquired. Subsequently, a second ultrasonic beam 302 is transmitted or received using a second frequency that is lower than the first frequency, and a second echo signal is collected. When generating ultrasonic beams, the higher the transmission frequency, the smaller the focus, i.e., the thinner the beam thickness can be set. In other words, the first ultrasonic beam 301 has a high frequency and a thin beam thickness. On the other hand, the second ultrasonic beam 302 has a low frequency and a thick beam thickness.

[0052] Of course, the frequency of the ultrasonic beam may be set for both transmission and reception of the ultrasonic beam. That is, a first echo signal may be collected by transmitting and receiving a first ultrasonic beam 301 using a first frequency, and a second echo signal may be collected by transmitting and receiving a second ultrasonic beam 302 using a second frequency. In this way, the second echo signal may include a portion of the first echo signal, or in the first generation example, the entire first echo signal, and signals outside the region of the first ultrasonic beam 301 may be collected.

[0053] Next, beam setting for the detection target according to the first generation example will be described with reference to FIG.

[0054] Hereinafter, assuming a puncture needle 30 as the detection target, an example of collecting echo signals based on a first ultrasonic beam 301 and a second ultrasonic beam 302 will be shown, similar to FIG. 3. The portion of the first ultrasonic beam 301 where the puncture needle 30 is visualized is indicated by a solid line, and the portion not visualized by the first ultrasonic beam 301 is indicated by a dashed line. Because the puncture needle 30 is located outside the region of the first ultrasonic beam 301, it is not possible to determine whether the puncture needle 30 is present outside the plane using only the ultrasound image based on the first ultrasonic beam 301. On the other hand, because the puncture needle 30 is included in the region of the second ultrasonic beam 302, the puncture needle 30 is visualized in the ultrasound image based on the second ultrasonic beam 302, and therefore it is possible to determine that the puncture needle 30 is present outside the plane of the ultrasound image based on the first ultrasonic beam 301.

[0055] In this way, by changing the frequency of the ultrasonic beam, echo signals can be collected from different regions, and therefore the second ultrasonic beam 302 can collect echo signals in a spatial region outside the plane of the first ultrasonic beam 301. Therefore, the detection function 188 can easily detect whether or not the puncture needle 30 is present in the ultrasound image based on the first echo signal, which is a desired cross-sectional image.

[0056] Next, a display example of the ultrasound image and the superimposed image in the first generation example will be described with reference to FIG. 5(a) is an ultrasound image 51 based on the first ultrasound beam 301, showing the state in which the puncture needle 30 has been inserted into the target T. As shown in FIG. 4, the puncture needle 30 is outside the area of ​​the first ultrasound beam 301, and therefore the tip of the puncture needle 30 appears to be located in the center of the tumor on the ultrasound image 51. However, in reality, as shown by the dashed line, part of the puncture needle 30 is outside the plane of the ultrasound image 51, and the tip is also outside the plane.

[0057] 5(b) is a difference image 52 based on the difference signal between the first ultrasonic beam 301 and the second ultrasonic beam 302. From the difference image 52, it is possible to detect the presence of the puncture needle 30 in the spatial region of the second ultrasonic beam 302.

[0058] 5(c) shows a superimposed image 53 in which a difference image 52 is superimposed on an ultrasound image 51. In the superimposed image 53, the puncture needle 30 depicted in the difference image 52 is displayed in a different color from the puncture needle 30 depicted in the ultrasound image 51, in the example of FIG. 5, a different pattern 54. In this way, according to the superimposed image 53, the puncture needle 30 existing outside the plane of the ultrasound image 51 is displayed in a different pattern 54, and therefore the user can easily recognize that the puncture needle and its tip are outside the plane of the ultrasound image 51.

[0059] The display mode of the puncture needle 30 depicted in the difference image 52 is not limited to different display colors or hatching patterns, and other display modes such as blinking display, thick line display, etc. In other words, any display mode is possible as long as the portion of the puncture needle 30 depicted in the difference image 52 is displayed in a distinguishable manner in the superimposed image 53.

[0060] Next, a second example of generation of sound beams according to the very first embodiment will be described with reference to FIG. 6 shows an example in which the apertures are different for each ultrasonic beam. The effective aperture 601 of the first ultrasonic beam in the elevation direction of the ultrasonic beam is set narrow, and a first echo signal is collected. Subsequently, the effective aperture 602 of the second ultrasonic beam is set wider than the effective aperture 601 of the first ultrasonic beam, and a second echo signal is collected. In this way, echo signals can be collected from different regions by changing the effective aperture of the ultrasonic beam. Therefore, similar to the first generation example, the second echo signal can collect signals outside the region of the first echo signal.

[0061] According to the first embodiment described above, the acquisition function acquires first and second echo signals based on two ultrasonic beams in regions that at least partially overlap and differ in the elevation direction. The difference calculation function calculates a difference signal between the first and second echo signals. The display control function displays a difference image based on the difference signal or displays it superimposed on a desired ultrasonic image. This makes it possible to easily determine whether or not the detection target exists outside the plane based on whether or not the detection target exists in the differential image.

[0062] (Second embodiment) The second embodiment differs from the first embodiment in that three ultrasonic beams with different acquisition regions are collected to detect the amount and direction of displacement of the detection target from a desired cross-sectional image. The configuration of the ultrasound diagnostic device 1 according to the second embodiment is similar to the configuration of the ultrasound diagnostic device 1 according to the first embodiment.

[0063] Next, an example of the operation of the ultrasonic diagnostic apparatus according to the second embodiment will be described with reference to the flowchart of FIG. The processes from step SA1 to step SA3, step SA4, and step SA6 to step SA9 are the same as those in the first embodiment.

[0064] In step SB1, the processing circuitry 180 is configured by the acquisition function 184 to change the area of ​​the beam in the elevation direction so as to be different from the first ultrasonic beam and the second ultrasonic beam.

[0065] In step SB2, the processing circuit 180 collects a third echo signal based on the third ultrasonic beam based on the conditions changed in step SB1 using the collection function 184. The region of the third ultrasonic beam is assumed to be a region that includes the first ultrasonic beam and the second ultrasonic beam, or a region in the opposite elevation direction to the second ultrasonic beam with respect to the first ultrasonic beam.

[0066] In step SB3, the processing circuit 180 calculates the difference between the first echo signal and the second echo signal after the speckle suppression process using the difference calculation function 186 to calculate a first difference signal, and further calculates the difference between the third echo signal and the first echo signal or the second echo signal to calculate a second difference signal.

[0067] In step SB4, the processing circuit 180 detects the amount and direction of displacement of the detection target using the detection function 188. Specifically, for example, when the region of the third ultrasonic beam is a region that includes the first ultrasonic beam and the second ultrasonic beam, by comparing the first differential signal and the second differential signal, if the first differential signal includes the detection target but the second differential signal does not include the detection target, it can be determined that the detection target does not exist in the region of the ultrasonic beam corresponding to the third echo signal. This makes it possible to detect the amount of displacement, i.e., the extent to which the detection target is outside the plane of the ultrasound image.

[0068] Furthermore, when the region of the third ultrasonic beam is a region in the opposite elevation direction to the second ultrasonic beam with respect to the first ultrasonic beam as the reference, by comparing the first differential signal and the second differential signal, it can be determined that the detection target exists in the direction of the second ultrasonic beam or the third ultrasonic beam that is below the differential signal containing the detection target, thereby making it possible to detect the direction in which the detection target is shifted outside the plane of the ultrasound image.

[0069] In step SB5, the processing circuit 180 displays on the screen whether the detection target is located outside the plane or not, and if the detection target is located outside the plane, the amount or direction of the deviation, using the display control function 187. This information may be displayed together with the superimposed image generated in step SA8.

[0070] Next, a third example of generation of an ultrasonic beam when detecting the amount of displacement of the detection object will be described with reference to FIG. In the third generation example shown in FIG. 8, the beam shape of the ultrasonic beam is changed between transmission and reception, and three types of echo signals having different beam shapes in the elevation direction are acquired.

[0071] The first pattern of the first ultrasound beam for acquiring the first echo signals is a focused wave that focuses the beam at a particular depth both on transmit and receive. The second pattern of the second ultrasonic beam for collecting the second echo signal is a focused wave when transmitted and a defocused plane wave when received. The third pattern of the third ultrasonic beam for collecting the third echo signal is a plane wave both during transmission and reception. The thicknesses of the ultrasonic beams in the elevation direction according to the first to third patterns are as follows, in order of decreasing thickness: first pattern, second pattern, and third pattern.

[0072] Next, a fourth example of generation of an ultrasonic beam, which is another example for detecting the amount of displacement of the detection object, will be described with reference to FIG. In the fourth generation example shown in Fig. 9, the beam shape of the ultrasonic beam is changed in the same way as in Fig. 8, and three types of echo signals with different beam shapes in the elevation direction are acquired. Here, an example is shown in which the beam shape is changed regardless of whether it is during transmission or reception as shown in Fig. 8.

[0073] The first ultrasonic beam 901 for collecting the first echo signal is a focused wave. The second ultrasonic beam 902 for collecting the second echo signal is a plane wave. The third ultrasonic beam 903 for collecting the third echo signal is a diverging wave. The thicknesses of the ultrasonic beams in the elevation direction are the first ultrasonic beam 901, the second ultrasonic beam 902, and the third ultrasonic beam 903 in order of decreasing thickness.

[0074] Next, beam setting for the detection target according to the fourth generation example will be described with reference to FIG. 10 shows an example in which echo signals are collected using the first ultrasonic beam 901, the second ultrasonic beam 902, and the third ultrasonic beam 903 shown in Fig. 9, assuming visualization of the puncture needle 30. As in Fig. 4, the portion where the puncture needle 30 is visualized is shown by a solid line, and the portion where the puncture needle 30 is not visualized is shown by a dashed line. As shown in FIG. 10, it is assumed that the puncture needle 30 is present in the areas of a first ultrasonic beam 901, a second ultrasonic beam 902, and a third ultrasonic beam 903.

[0075] Next, a display example of an ultrasound image and a superimposed image in the fourth generation example will be described with reference to FIG. FIG. 11(a) is an ultrasound image 51 based on the first ultrasound beam 901 similar to that in FIG. 5(a). 11(b) is a difference image 52 based on a first difference signal between the first ultrasonic beam 901 and the second ultrasonic beam 902. Since the puncture needle 30 is depicted in the difference image 52, it can be seen that the puncture needle 30 is present in the region of the second ultrasonic beam 902.

[0076] 11(c) is a difference image 61 based on a second difference signal between the second ultrasonic beam 902 and the third ultrasonic beam 903. Since the puncture needle 30 is depicted in the difference image 61, it is possible to detect the presence of the puncture needle 30 in the region of the third ultrasonic beam 903. 11(d) shows a superimposed image 62 in which the difference image 52 and the difference image 61 are superimposed on the ultrasound image 51. In the superimposed image 62, the puncture needle 30 depicted in the difference image 52 and the difference image 61 is displayed in different patterns (pattern 54, pattern 63). Specifically, the puncture needle 30 depicted in the difference image 52 is displayed in pattern 54, and the puncture needle 30 depicted in the difference image 61 is displayed in pattern 63. Note that, for example, the processing circuitry 180 may use the detection function 188 to calculate the length of the puncture needle 30 shown in patterns 54 and 63, and display information on the out-of-plane length of the puncture needle as a displacement amount together with the superimposed image 62.

[0077] Also, for example, assume that the puncture needle 30 is present in the difference image 52 based on the first difference signal between the second echo signal and the first echo signal, but is not present in the difference image 61 based on the second difference signal between the third echo signal and the second echo signal. In this case, the puncture needle 30 is present in the region of the second ultrasonic beam 902, but is not present in the region of the third ultrasonic beam 903. Therefore, it can be determined that the tip of the puncture needle 30 is present in the region of the second ultrasonic beam 902. Note that similar processing can be performed by using the difference signal between the third echo signal and the first echo signal as the second difference signal instead of the difference signal between the third echo signal and the second echo signal, and detecting whether the puncture needle 30 is present in the difference image 61 based on the second difference signal.

[0078] Next, a fifth example of generation of an ultrasonic beam when detecting the direction of displacement of the detection object will be described with reference to FIG. The fifth generation example differs in that the delay times (delay patterns) of the multiple elements of the ultrasonic probe 101 are shifted and the beam is tilted in the elevation direction to collect data. Specifically, the first ultrasonic beam 1201 is subjected to beam narrowing assuming a normal focused wave. The delay pattern of the second ultrasonic beam 1202 is controlled for each element of the ultrasonic probe 101 so that the beam directivity is directed toward the far side in the elevation direction. The delay pattern of the third ultrasonic beam 1203 is controlled for each element of the ultrasonic probe 101 so that the beam directivity is directed toward the opposite side of the second ultrasonic beam 1202, that is, toward the near side in the elevation direction, with respect to the first ultrasonic beam 1201.

[0079] Next, beam setting for the detection target according to the fifth generation example will be described with reference to FIG. 13 shows an example in which echo signals are collected using the first ultrasonic beam 1201, the second ultrasonic beam 1202, and the third ultrasonic beam 1203 shown in Fig. 12, assuming visualization of the puncture needle 30. As in Fig. 4, the portion where the puncture needle 30 is visualized is shown by a solid line, and the portion where the puncture needle 30 is not visualized is shown by a dashed line.

[0080] 13, the puncture needle 30 is present in the areas of the first ultrasonic beam 1201, the second ultrasonic beam 1202, and the third ultrasonic beam 1203. Furthermore, it is assumed that the tip of the puncture needle 30 is present in the second ultrasonic beam 1202.

[0081] Next, a display example of an ultrasound image and a superimposed image in the fifth generation example will be described with reference to FIG. FIG. 14(a) is an ultrasound image 51 based on the first ultrasound beam 1201 similar to that in FIG. 11(a). 14(b) is a difference image 52 based on the first difference signal between the first ultrasonic beam 1201 and the second ultrasonic beam 1202. Since the puncture needle 30 is depicted in the difference image 52, it can be seen that the puncture needle 30 is present in the region of the second ultrasonic beam 1202. 14(c) is a difference image 61 based on the second difference signal between the second ultrasonic beam 1202 and the third ultrasonic beam 1203. The puncture needle 30 is not depicted in the difference image 61. This shows that the puncture needle 30 is not present in the region of the third ultrasonic beam 1203.

[0082] 14(d) shows a superimposed image 62 in which the difference image 52 and the difference image 61 are superimposed on the ultrasound image 51. In the superimposed image 62, the puncture needle 30 depicted in the difference image 52 is displayed in a different pattern 54 so as to be distinguishable from the portion of the puncture needle 30 depicted in the ultrasound image 51. By looking at the superimposed image 62, it is clear that the puncture needle 30 is present in the region of the second ultrasound beam 1202, and therefore it is possible to easily grasp the direction of displacement of the puncture needle 30, i.e., whether the puncture needle 30 is present on the far side or the near side in the elevation direction relative to the ultrasound image 51.

[0083] Note that a message 65 such as a speech bubble may be displayed for pattern 54, such as "back of screen" or "front of screen" in FIG. 14(d). Furthermore, the display color may be fixed depending on the direction of displacement, allowing the user to recognize the direction of displacement. For example, the portion of the puncture needle 30 that has shifted to the back of the screen may be displayed in blue, and the portion of the puncture needle 30 that has shifted to the front of the screen may be displayed in red. This allows the user to visually recognize the direction of displacement of the puncture needle 30.

[0084] For example, the processing circuit 180 may use the detection function 188 to calculate the length of the puncture needle 30 indicated by the pattern 54, and display the out-of-plane length information of the puncture needle 30 as the amount of deviation together with the superimposed image 62 and the direction of deviation.

[0085] In the fourth and fifth examples of generating an ultrasonic beam, examples are shown in which echo signals are collected by ultrasonic beams for three different regions, but the present invention is not limited to this, and four or more echo signals may be collected to detect the amount and direction of displacement of the detection target. However, the more echo signals are used, the lower the frame rate becomes and the less real-time the processing becomes. Therefore, the number of ultrasonic beams used for processing may be set according to the frame rate desired by the user.

[0086] In the above example, it is assumed that information on whether or not the detection target exists outside the plane of the ultrasound image is presented, but information on whether or not the detection target exists within the ROI may also be presented. A display example of an ultrasound image and a superimposed image when the ROI is the target will be described with reference to FIG.

[0087] Fig. 15 shows an example in which an ROI 1501 is set on an ultrasound image 51, assuming the superimposed image 62 shown in Fig. 14. As shown in Fig. 15, when the puncture needle 30 is detected outside the plane of the ultrasound image 51, a message 1502 such as "The tip of the puncture needle has come off the ROI" may be displayed.

[0088] According to the second embodiment described above, the acquisition function acquires first, second, and third echo signals based on three ultrasonic beams in areas that at least partially overlap and differ in the elevation direction. The difference calculation function calculates a first difference signal between the first and second echo signals and a second difference signal between the third echo signal and the second echo signal or the first echo signal. The display control function displays a difference image based on the first difference signal and the second difference signal or displays it superimposed on a desired ultrasound image.

[0089] This makes it easy to determine whether the detection target exists outside the plane based on whether the detection target exists in the differential image, and also makes it possible to detect the amount and direction of deviation of the detection target, thereby providing more useful information to the user.

[0090] The term "processor" used in the above description refers to a circuit such as a central processing unit (CPU), a graphics processing unit (GPU), an application specific integrated circuit (ASIC), or a programmable logic device (e.g., a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), or a field programmable gate array (FPGA)). If the processor is a CPU, for example, the processor realizes its function by reading and executing a program stored in a memory circuit. On the other hand, if the processor is an ASIC, for example, the program is not stored in a memory circuit, but the function is directly incorporated into the processor circuit as a logic circuit. Note that each processor in this embodiment 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 its function. Furthermore, multiple components in the diagram may be integrated into a single processor to realize its function.

[0091] In addition, each function according to the embodiment can be realized by installing a program that executes the above-described processes in a computer such as a workstation and expanding the program in memory. In this case, the program that causes the computer to execute the above-described method can be stored and distributed on a storage medium such as a magnetic disk (such as a hard disk), an optical disk (such as a CD-ROM or DVD), or a semiconductor memory.

[0092] According to at least one of the embodiments described above, it is possible to easily determine whether or not the detection target exists outside the plane.

[0093] Although several embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations of embodiments can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0094] 1. Ultrasound diagnostic equipment 30 puncture needle 51 Ultrasound images 52,61 Difference image 53,62 Superimposed images 54,63 patterns 65 Messages 100 Device body 101 Ultrasound probe 102 Input Device 103 Output Device 104 External device 110 Ultrasonic transmission circuit 120 Ultrasonic receiving circuit 130 Internal memory circuit 140 image memory 150 Input Interface 160 output interface 170 Communication Interface 180 Processing Circuit 181 B-mode processing function 182 Doppler processing function 183 Image generation function 184 Collection Function 185 Speckle suppression function 186 Difference calculation function 187 Display control function 188 Detection Function 189 System Control Functions 301,901,1201 First ultrasonic beam 302,902,1202 Second ultrasonic beam 903,1203 Third ultrasonic beam 601,602 Effective aperture 1502 Messages

Claims

1. an acquisition unit that acquires a first echo signal based on a first ultrasonic beam and acquires a second echo signal based on a second ultrasonic beam that at least partially overlaps with a region of the first ultrasonic beam and has a beam region different from that of the second ultrasonic beam in an elevation direction; a calculation unit that calculates a differential signal that is a difference between the first echo signal and the second echo signal; a display control unit that displays a differential image based on the differential signal; An ultrasound diagnostic device comprising:

2. the calculation unit performs threshold processing to extract signal values ​​in the differential signal that are equal to or greater than a threshold; The ultrasound diagnostic apparatus according to claim 1 , wherein the display control unit displays the difference image based on the extracted signal value.

3. The ultrasonic diagnostic apparatus according to claim 1 , further comprising a detection unit that detects whether a detection target is depicted in the difference image.

4. The ultrasound diagnostic apparatus according to claim 3 , wherein the detector determines that at least a part of the detection target is located outside the plane of a desired cross-sectional image when the detection target is depicted in the difference image.

5. a suppression unit that performs speckle suppression processing on the first echo signal and the second echo signal, The ultrasonic diagnostic apparatus according to claim 1 , wherein the calculation unit generates the differential signal based on the first echo signal and the second echo signal on which the speckle suppression processing has been performed.

6. The ultrasonic diagnostic apparatus according to claim 1 , wherein the first ultrasonic beam and the second ultrasonic beam are ultrasonic beams having different frequencies.

7. The ultrasonic diagnostic apparatus according to claim 1 , wherein the first ultrasonic beam and the second ultrasonic beam are ultrasonic beams transmitted or received by different apertures in the elevation direction.

8. The ultrasonic diagnostic device according to claim 1 , wherein the first ultrasonic beam and the second ultrasonic beam are ultrasonic beams whose beam regions are different by controlling a delay time of a signal in the elevation direction.

9. the acquisition unit further acquires a third echo signal based on a third ultrasonic beam having a beam shape that includes regions of the first ultrasonic beam and the second ultrasonic beam; the calculation unit calculates a first difference signal that is a difference between the first echo signal and the second echo signal, and a second difference signal between the third echo signal and the first echo signal or the second echo signal; 2. The ultrasonic diagnostic apparatus according to claim 1, further comprising a detection unit that calculates a deviation amount indicating a degree to which at least a portion of the detection target is located outside the plane of a desired cross-sectional image, using the first difference signal and the second difference signal.

10. The collecting unit further collects a third echo signal based on a third ultrasonic beam that at least partially overlaps with a region of the first ultrasonic beam and is directed toward a region in an opposite elevation direction to the second ultrasonic beam with respect to the first ultrasonic beam; the calculation unit calculates a first difference signal that is a difference between the first echo signal and the second echo signal, and a second difference signal that is a difference between the third echo signal and the first echo signal or the second echo signal; The ultrasonic diagnostic apparatus according to claim 1 , further comprising a detection unit that calculates a direction of deviation in the elevation direction for at least a part of the detection target using the first difference signal and the second difference signal.

11. The ultrasound diagnostic apparatus according to claim 1 , wherein the display control unit displays the difference image superimposed on the ultrasound image based on the first echo signal in a display color different from that of the ultrasound image.

12. Acquire a first echo signal based on a first ultrasonic beam, and acquire a second echo signal based on a second ultrasonic beam that at least partially overlaps with a region of the first ultrasonic beam and has a different beam region in an elevation direction; calculating a differential signal that is a difference between the first echo signal and the second echo signal; and displaying a difference image based on the difference signal.

13. On the computer, an acquisition function of acquiring a first echo signal based on a first ultrasonic beam and acquiring a second echo signal based on a second ultrasonic beam that at least partially overlaps with the area of ​​the first ultrasonic beam and has a different beam area in the elevation direction; a calculation function for calculating a differential signal that is a difference between the first echo signal and the second echo signal; a display control function for displaying a differential image based on the differential signal; Ultrasound diagnostic program to achieve this.

Images