Ultrasonic diagnostic equipment and control method thereof

Abstract

An ultrasonic diagnostic device and a control method thereof are provided. In the method of controlling the ultrasonic diagnostic device, a plurality of tracking pulses are emitted at preset intervals to observe shear waves induced in a region of interest (ROI) of an object, a plurality of receiving scan lines corresponding to each tracking signal in the plurality of tracking pulses are set, and signal processing is selectively performed on the plurality of receiving scan lines.

Description

[0001] This application is based on and claims the benefit of priority from Korean Patent Application No. 2019-0030525 filed on March 18, 2019 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. Technical Field

[0002] The present disclosure relates to an ultrasonic diagnostic device and a control method thereof. Background Art

[0003] Ultrasonic diagnostic equipment is used to radiate ultrasonic signals generated from an ultrasonic probe transducer to a target site inside the object through the surface of the object, and non-invasively acquire a tomographic image of soft tissue or a blood flow image using information about the ultrasonic signals (ultrasonic echo signals) reflected from the object.

[0004] Ultrasonic diagnostic equipment has advantages in that it is compact and inexpensive, can display in real time, and is highly safe compared to X-ray diagnostic equipment because there is no risk of exposure to X-rays, etc., and therefore is widely used in cardiac, breast, abdominal, urological, and obstetrical diagnoses.

[0005] On the other hand, human tissue has elasticity, and diseased tissue can be detected based on the elasticity of the tissue. Ultrasonic diagnostic equipment can measure the elasticity of tissue and image the elasticity. In detail, the ultrasonic diagnostic equipment can calculate the elasticity by estimating the shear wave velocity and can generate an elastic image of the shear wave.

[0006] However, when diagnosing obese patients, severe reverberation occurs due to the fat layer, which makes it difficult to accurately measure elasticity. Summary of the invention

[0007] Therefore, an object of the present disclosure is to provide an ultrasonic diagnostic apparatus and a control method thereof that can accurately measure elasticity by improving the performance of shear wave observation even in the presence of reverberation.

[0008] Another object of the present disclosure is to provide an ultrasonic diagnostic apparatus capable of accurately measuring elasticity by setting the interval of tracking pulses for shear wave observation to be wide when a region of interest (ROI) is set to be wide, and a control method thereof.

[0009] Additional aspects of the disclosure will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the disclosure.

[0010] Therefore, one aspect of the present disclosure is to provide a method for controlling an ultrasonic diagnostic device, the method comprising: transmitting a push pulse to a region of interest (ROI) of a target object to induce a shear wave; adjusting the position of a focus to which a plurality of tracking pulses are transmitted based on the position of the ROI; transmitting the plurality of tracking pulses to the ROI; receiving an ultrasonic echo signal reflected from the ROI in response to the plurality of tracking pulses; estimating a shear wave velocity associated with the ROI based on the ultrasonic echo signal; generating a shear wave elasticity image based on the shear wave velocity; and outputting the shear wave elasticity image on a display.

[0011] The method may further include setting the ROI in a radial form, wherein the step of transmitting the plurality of tracking pulses includes transmitting the plurality of tracking pulses radially to the ROI in the radial form.

[0012] Adjusting the position of the focus may include moving the focus into the ROI in response to movement of the ROI.

[0013] The step of receiving the ultrasonic echo signal may include setting a set of multiple receiving scan lines, each set corresponding to a corresponding one of the multiple tracking pulses, wherein the step of estimating the shear wave velocity may include selectively performing signal processing on the multiple receiving scan lines.

[0014] The step of estimating the shear wave velocity may include: grouping the receiving scan lines located at the same relative position in each set of the multiple receiving scan lines to generate multiple groups; estimating multiple shear wave velocities each corresponding to a corresponding one of the multiple groups; and determining the final shear wave velocity based on the multiple shear wave velocities.

[0015] The step of determining the final shear wave velocity may include determining an average value of the plurality of shear wave velocities or a weighted average value obtained using a reliability measurement index (RMI) on each of the plurality of shear wave velocities as the final shear wave velocity.

[0016] The step of estimating the shear wave velocity may include: selecting some reception scan lines from the plurality of reception scan lines; and estimating the shear wave velocity based on ultrasonic echo signals received along the selected some reception scan lines.

[0017] The step of selecting a receiving scan line may include selecting a receiving scan line adjacent to each of the plurality of tracking pulses from the set of the plurality of receiving scan lines.

[0018] The step of selecting a reception scan line may include selecting a reception scan line having a position error smaller than a predetermined value.

[0019] The step of estimating the shear wave velocity may also include: estimating the arrival time of the shear wave on each of the multiple receiving scan lines, wherein the step of selecting the receiving scan lines may include: selecting the receiving scan lines other than the receiving scan line with the minimum arrival time of the shear wave and the receiving scan line with the maximum arrival time of the shear wave.

[0020] Outputting the shear wave elasticity image may include displaying elasticity, depth, and a reliability measurement index (RMI).

[0021] Transmitting the plurality of tracking pulses may include transmitting the plurality of tracking pulses in an interleaved method.

[0022] The step of estimating the shear wave velocity may include: detecting the displacement of tissue at multiple sampling points of each of the multiple receiving scan lines; estimating the arrival time of the shear wave on each of the multiple receiving scan lines based on the displacement of the tissue; and estimating the shear wave velocity based on the difference between the distance between the multiple receiving scan lines and the arrival time of the shear wave on the multiple receiving scan lines.

[0023] Another aspect of the present disclosure is to provide an ultrasonic diagnostic device, which includes: an ultrasonic probe, configured to: transmit a push pulse to a region of interest (ROI) of a target object, transmit a plurality of tracking pulses to the ROI to observe the shear wave induced by the push pulse, and receive an ultrasonic echo signal reflected from the ROI in response to the plurality of tracking pulses; a controller, configured to: adjust the position of the focus to which the plurality of tracking pulses are transmitted based on the position of the ROI, estimate the shear wave velocity associated with the ROI based on the ultrasonic echo signal, and generate a shear wave elasticity image based on the shear wave velocity; and a display, on which the shear wave elasticity image is output.

[0024] The controller may set the ROI in a radial form, and control the ultrasound probe to radially transmit the plurality of tracking pulses to the ROI in the radial form.

[0025] The controller may move the focus into the ROI in response to movement of the ROI.

[0026] The controller may arrange sets of multiple reception scan lines, each set corresponding to a respective one of the plurality of tracking pulses, and the controller may selectively perform signal processing on the multiple reception scan lines.

[0027] The controller may group the receiving scan lines located at the same relative position in each set of the multiple receiving scan lines to generate multiple groups, may estimate multiple shear wave velocities each corresponding to a corresponding one of the multiple groups, and may determine a final shear wave velocity based on the multiple shear wave velocities.

[0028] The controller may determine an average value of the plurality of shear wave velocities or a weighted average value obtained using a reliability measurement index (RMI) on each of the plurality of shear wave velocities as the final shear wave velocity.

[0029] The controller may select some reception scan lines from the plurality of reception scan lines, and estimate the velocity of the shear wave based on ultrasound echo signals received along the selected some reception scan lines.

[0030] The controller may select a reception scan line adjacent to each tracking pulse of the plurality of tracking pulses from the set of the plurality of reception scan lines.

[0031] The controller may select a reception scan line having a position error smaller than a predetermined value.

[0032] The controller may estimate an arrival time of the shear wave on each of the plurality of reception scan lines and select reception scan lines other than a reception scan line having a minimum arrival time of the shear wave and a reception scan line having a maximum arrival time of the shear wave.

[0033] The controller may control the display to display elasticity, depth, and a reliability measurement index (RMI).

[0034] The controller may control the ultrasound probe to transmit the plurality of tracking pulses in an interleaved method.

[0035] The controller may detect the displacement of tissue at multiple sampling points of each of the multiple receiving scan lines, estimate the arrival time of the shear wave on each of the multiple receiving scan lines based on the displacement of the tissue, and estimate the shear wave velocity based on the difference between the distance between the multiple receiving scan lines and the arrival time of the shear wave on the multiple receiving scan lines. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] These and / or other aspects of the present disclosure will become apparent and more readily understood through the following description of embodiments in conjunction with the accompanying drawings, in which:

[0037] Figure 1 An ultrasonic diagnostic apparatus according to an embodiment is shown.

[0038] Figure 2 is a block diagram showing the configuration of an ultrasonic diagnostic apparatus according to the embodiment.

[0039] Figure 3 is a block diagram showing a configuration of an ultrasound probe according to an embodiment.

[0040] Figure 4 The transmission and reception of ultrasonic waves are shown.

[0041] Figure 5 is a flow chart schematically illustrating a method of estimating shear wave velocity.

[0042] Figure 6 The shear wave induced by the push pulse is shown.

[0043] Figure 7 The propagation of shear waves is shown.

[0044] Figure 8 An example of a method of detecting shear waves is shown.

[0045] Fig. 9 The emission of tracking pulses according to another example of a method of detecting shear waves is shown.

[0046] Fig.10 A method of transmitting multiple tracking pulses to widen the observation area is shown.

[0047] Fig.11 The radial emission of multiple tracking pulses is shown to suit the region of interest.

[0048] Fig.12 Multiple receive scan lines corresponding to a single tracking pulse are shown.

[0049] Fig.13 A sequence of sets of multiple tracking pulses and multiple receive scan lines is shown.

[0050] Fig.14 The relationship between the displacement of the tissue and the arrival time of the shear wave is shown.

[0051] Fig.15 The position error of multiple receive scan lines is shown.

[0052] Fig.16 The error in the shear wave arrival time for each of the multiple receive scan lines is shown.

[0053] Fig.17 Receive scan lines in a set of multiple receive scan lines that are located at the same relative position are shown.

[0054] Fig.18 The shear wave arrival times are shown for received scan lines located at the same relative positions.

[0055] Fig.19is a flowchart showing a method of controlling an ultrasonic diagnostic apparatus, which describes a method of estimating shear wave velocity by grouping reception scan lines.

[0056] Fig. 20 Shown is a diagram for describing Fig.19 Wavefront diagram of the method for estimating shear wave velocity shown in .

[0057] Fig.21 is a flowchart illustrating a method of controlling an ultrasonic diagnostic apparatus according to another embodiment, which describes a method of estimating shear wave velocity by selecting some reception scan lines.

[0058] Fig. 22 and Fig.23 Shown is a diagram for describing Fig.21 Wavefront diagram of the method for estimating shear wave velocity shown in .

[0059] Fig.24 and Fig.25 The intervals between multiple tracking pulses are shown.

[0060] Fig.26 and Fig. 27 The results of elasticity measurements according to the prior art are shown.

[0061] Fig.28 Results of elasticity measurement by the method of controlling an ultrasonic diagnostic apparatus according to an embodiment are shown. DETAILED DESCRIPTION

[0062] Throughout the specification, the same reference numerals refer to the same elements. All elements of the embodiments of the present disclosure will not be described, and descriptions of contents well known in the art or contents that overlap with each other in the embodiments will be omitted.

[0063] It will also be understood that the term "connected" or its derivatives refer to both direct and indirect connections, and that an indirect connection includes a connection through a wireless communication network.

[0064] It will also be understood that the terms “comprises” and / or “comprising”, when used in the present specification, recite the presence of stated features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements and / or components.

[0065] Although the terms "first", "second", "A", "B", etc. may be used to describe various components, the terms do not limit the corresponding components, but are used only for the purpose of distinguishing one component from another component. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form as well.

[0066] In addition, terms such as "component", "module" and "unit" described in the specification refer to a unit that processes at least one function or operation and may be implemented by software, hardware components (such as a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC)), or a combination of software and hardware.

[0067] The reference numerals used for the method steps are only for convenience of explanation and do not limit the order of the steps. Therefore, unless the context clearly indicates otherwise, the written order can be practiced in other ways.

[0068] The "object" may include a person or an animal, or a part of a person or an animal. For example, the object may include not only a block but also an organ such as a liver, a heart, a uterus, a brain, a breast, an abdomen, or a blood vessel. In addition, in the specification, the "user" may be a doctor, a nurse, a clinical pathologist, a medical imaging expert, etc., and may be a technician who develops and repairs medical equipment, but is not limited thereto.

[0069] The terms “ultrasound image” and “image of an object” refer to an image of an object obtained using ultrasound waves.

[0070] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0071] Figure 1 An ultrasonic diagnostic apparatus according to an embodiment is shown.

[0072] Reference Figure 1 , the ultrasonic diagnostic apparatus 1 includes an ultrasonic probe 100 and a main body 200. The ultrasonic probe 100 may transmit an ultrasonic signal to an object to be diagnosed and receive an ultrasonic echo signal reflected from the object. The ultrasonic probe 100 receives the ultrasonic echo signal reflected from the object and converts the ultrasonic echo signal into an electrical signal (hereinafter, referred to as an ultrasonic signal).

[0073] The ultrasonic probe 100 may be connected to the main body 200 of the ultrasonic diagnostic apparatus 1 through the cable 120, and may receive various signals required for controlling the ultrasonic probe 100 from the main body 200. In addition, the ultrasonic probe 100 may transmit an analog signal or a digital signal corresponding to an ultrasonic echo signal to the main body 200.

[0074] In addition, the ultrasound probe 100 may be implemented as a wireless probe, and may transmit and receive signals through a network formed between the ultrasound probe 100 and the main body 200. Figure 3 A specific embodiment of the ultrasound probe 100 is described.

[0075] The body 200 may include a probe selection assembly (PSA) board 250, a control panel 260, and a display 270 (270-1 and 270-2). The PSA board 250 includes a port connected to the ultrasound probe 100. The PSA board 250 may activate the ultrasound probe 100 according to a user command input through the control panel 260 and a control of the controller 300. One end of the cable 120 includes a connector 130, and the connector 130 may be connected to the port of the PSA board 250.

[0076] The control panel 260 is a device that receives a command from a user for operating the ultrasonic diagnostic apparatus 1. The control panel 260 may receive setting information about the ultrasonic probe 100, and receive various control commands related to the operation of the main body 200.

[0077] The control panel 260 may include a keyboard. The keyboard may include buttons, switches, knobs, a touch pad, a trackball, etc. In addition, the control panel 260 may include a first display 270-1. The first display 270-1 may display a graphical user interface (GUI) for controlling the operation of the ultrasonic diagnostic apparatus 1. The first display 270-1 may display relevant information for optimizing the ultrasonic image, such as a menu or an auxiliary image.

[0078] The first display 270-1 may include a touch panel and receive a user's touch input on the graphical user interface. The first display 270-1 may display a graphical user interface having the same shape as a button included in a keyboard. The user may input a command for controlling the ultrasonic diagnostic apparatus 1 through a touch input to the first display 270-1.

[0079] The second display 270-2 may display an ultrasonic image. The ultrasonic image may be a two-dimensional (2D) ultrasonic image or a three-dimensional (3D) stereoscopic ultrasonic image, and various ultrasonic images may be displayed according to the operation mode of the ultrasonic diagnostic apparatus 1. In addition, the second display 270-2 may display menus required for ultrasonic diagnosis, guide items, information on the operation status of the ultrasonic probe 100, and the like.

[0080] The second display 270 - 2 may display the shear wave elasticity image overlapped or registered with the reference ultrasound image.

[0081] The second display 270-2 may also include a touch panel and receive a user's touch input on the graphical user interface. The user may input a command for controlling the ultrasonic diagnostic apparatus 1 through the touch input on the second display 270-2.

[0082] The display 270 may be implemented as various display devices such as a liquid crystal display (LCD), a light emitting diode (LED) panel, a plasma display panel (PDP), and an organic light emitting diode (OLED) panel.

[0083] Figure 2 is a block diagram showing the configuration of an ultrasonic diagnostic apparatus according to the embodiment.

[0084] Reference Figure 2 The ultrasound probe 100 may be a linear array probe, a curved array probe, a phased array probe, or a volume probe. The ultrasound probe 100 is not limited thereto and may include various probes such as an endocavity probe, a convex probe, a matrix probe, and / or a 3D probe.

[0085] The main body 200 of the ultrasonic diagnostic apparatus 1 may further include beamformers 281 and 282 , an image processor 290 , and a controller 300 .

[0086] The beamformer can be divided into a transmit beamformer 281 and a receive beamformer 282. When an image is obtained using an ultrasound signal, a beamforming technique is used to increase the resolution of the image. The transmit beamformer 281 may apply a transmit pulse to the ultrasound probe 100. The transmit beamformer 281 may apply an appropriate time delay so that the ultrasound signals to be transmitted by a plurality of transducer elements are simultaneously focused at one focal point and generate a transmit beam. The transducer array 110 may transmit the transmit beam to a target site in the object.

[0087] In addition, the transmit beamformer 281 can generate a push pulse that is transmitted along a push line. The push pulse can be radiated to a region of interest (ROI) of the object to cause displacement of the tissue and induce shear waves. The shear wave velocity is measured using the displacement of the tissue, which will be described below. The push pulse can be a focused beam with a relatively high focus.

[0088] The ultrasound transmitted to the object may be reflected from the object and may be incident back to the transducer array 110 of the ultrasound probe 100. The reflected ultrasound signal may be defined as an ultrasound echo signal.

[0089] The reception beamformer 281 performs analog / digital conversion on the ultrasonic echo signal received from the ultrasonic probe 100 and performs reception beamforming. The reception beamformer 281 may apply a time delay to the ultrasonic echo signal reflected from the focus and returned to the transducer element and simultaneously accumulate the ultrasonic echo signal.

[0090] In addition, beamformers 281 and 282 may be provided in the ultrasound probe 100. For example, when the ultrasound probe 100 is a wireless probe, the ultrasound probe 100 may include the beamformers 281 and 282.

[0091] The image processor 290 filters out noise components in a reception beam to improve image quality of an ultrasound image, performs an envelope detection process for detecting the intensity of a received signal, and generates digital ultrasound image data.

[0092] The image processor 290 may perform scan conversion to convert scan lines of digital ultrasound image data so that the digital ultrasound image data is displayed on the display 270. In addition, the image processor 290 performs image processing on the ultrasound echo signal to generate an A-mode image, a B-mode image, a D-mode image, an E-mode image, an M-mode image, a Doppler image, and / or a 3D ultrasound image. The image processor 290 performs RGB processing on the ultrasound image data so that the ultrasound image is displayed on the display 270, and transmits the ultrasound image data to the display 270.

[0093] Also, the image processor 290 may perform image processing for displaying various pieces of additional information on the ultrasound image.

[0094] Despite Figure 2 2 and 3 , the image processor 290 is shown to be separate from the controller 300 , but the controller 300 may include the image processor 290 .

[0095] The display 270 may display an ultrasonic image and various types of information processed by the ultrasonic diagnostic apparatus 1. The display 270 may display various graphic user interfaces for adjusting a generated ultrasonic image.

[0096] The controller 300 may control the operation of the ultrasonic diagnostic apparatus 1 and the signal flow between the internal components of the ultrasonic diagnostic apparatus 1. The controller 300 may include a processor 310 and a memory 320. The controller 300 may be implemented as a processing board in which the processor 310 and the memory 320 are mounted on a circuit board. The processor 310 and the memory 320 may be connected via a bus. The processor 310 may be provided in a single unit or in a plurality of units.

[0097] The controller 300 may be implemented using a plurality of logic gates, or may be implemented using a combination of a general-purpose microprocessor and a memory 320 configured to store a program executable in the microprocessor.

[0098] The memory 320 refers to a storage medium that stores algorithms and data required for the operation of each component in the ultrasonic diagnostic apparatus 1. The memory 320 may include a high-speed random access memory, a disk, an SRAM, a DRAM, a ROM, etc. In addition, the memory 320 may be detachable from the ultrasonic diagnostic apparatus 1. The memory 320 may include a compact flash (CF) card, a secure digital (SD) card, a smart media (SM) card, a multimedia card (MMC), or a memory stick, but is not limited thereto.

[0099] The controller 300 may be electrically connected to each of the PSA board 250 , the control panel 260 , the display 270 , and the beamformers 281 and 282 , and may generate control signals for controlling components in the ultrasound probe 100 and the body 200 .

[0100] Refer to the following Figures 5 to 14 The detailed operation of the controller 300 is described.

[0101] Figure 3 is a block diagram showing a configuration of an ultrasound probe according to an embodiment.

[0102] Reference Figure 3 , the ultrasound probe 100 may include a transducer array 110 , a cable 120 , a connector 130 , and a probe controller 170 .

[0103] The transducer array 110 is provided at the end of the ultrasound probe 100. The transducer array 110 includes an array of a plurality of ultrasound transducer elements. The transducer array 110 generates ultrasound waves while vibrating by a pulse signal or alternating current applied by the transmit beamformer 281 of the main body 200. The generated ultrasound waves are transmitted to a target site inside the object.

[0104] The ultrasound generated by the transducer array 110 may be transmitted to a plurality of focal points for a plurality of target sites inside the object. That is, the ultrasound may be multi-focused and may be transmitted to a plurality of target sites.

[0105] The ultrasound emitted by the transducer array 110 is returned to the transducer array 110 as an ultrasound echo signal reflected from a target site inside the object. When the ultrasound echo signal arrives, the transducer array 110 vibrates at a predetermined frequency corresponding to the frequency of the ultrasound echo signal, and outputs an alternating current having a frequency corresponding to the vibration frequency. Therefore, the transducer array 110 can convert the ultrasound echo signal into a predetermined electrical signal.

[0106] Reference Figure 5 , the ultrasound probe 100 may transmit a reference pulse 511 to the ROI and receive a first ultrasound echo signal 513 as a result of the reference pulse 511 being reflected from the region of interest. The reference pulse 511 has a beam profile. The width of the beam profile may be adjusted.

[0107] The ultrasonic diagnostic apparatus 1 may generate a first ultrasonic image based on the first ultrasonic echo signal 513. The first ultrasonic image may be a reference ultrasonic image distinguished from a shear wave elastic image and representing the position of tissue before force is applied to the ROI. The first ultrasonic image may be a B-mode image or an M-mode image of the ROI.

[0108] In addition, the ultrasonic probe 100 can induce shear waves by transmitting a push pulse to the ROI of the object, and can transmit a tracking pulse for observing the shear wave to the ROI of the object and receive an ultrasonic echo signal as a result of reflection of the tracking pulse. The ultrasonic echo signal obtained by the reflection of the tracking pulse can be defined as a second ultrasonic echo signal. The controller 300 of the ultrasonic diagnostic device 1 can generate a second ultrasonic image based on the second ultrasonic echo signal. That is, the second ultrasonic image can be defined as a shear wave captured image.

[0109] The transducer elements included in the transducer array 110 may be selectively activated. Through the selective activation of the transducer elements, the width of the transmit beam may be adjusted. In addition, a plurality of tracking pulses may be transmitted at preset intervals.

[0110] The probe controller 170 may include a processor 171 and a memory 172. The processor 171 of the probe controller 170 may be a general-purpose microprocessor, and the memory 172 may store a program executable by the processor 171. The probe controller 170 transmits and receives data to and from the body 200, and controls the overall operation of the ultrasound probe 100.

[0111] The ultrasound probe 100 may further include a T / R switch and a beamformer. The T / R switch serves as a switch for controlling conversion between an operation in which the transducer array 110 radiates an ultrasound signal and an operation in which the transducer array 110 receives a reflected echo signal.

[0112] The components included in the ultrasound probe 100 are not limited to Figure 3 Those components shown in , and may be provided in various combinations.

[0113] Figure 4 is a flow chart schematically illustrating a method of estimating shear wave velocity.

[0114] Reference Figure 4 , the ultrasound probe 100 may induce shear waves by transmitting a push pulse to the ROI of the object (410). In detail, the ultrasound probe 100 may cause displacement of tissue in the object by irradiating the object with a focused beam. When the focused beam is irradiated to the object, the tissue in the object is deformed according to the axial movement caused by the focused beam, thereby causing displacement of the tissue. The tissue displacement may cause shear wave propagation.

[0115] Thereafter, the ultrasound probe 100 may transmit a tracking pulse for observing shear waves to the ROI of the object, and receive an ultrasound echo signal as a result of reflection of the tracking pulse (420). The ultrasound echo signal generated by the reflection of the tracking pulse may be defined as a second ultrasound echo signal. The tracking pulse has a beam profile of a predetermined width. The tracking pulse may be sequentially transmitted to a plurality of points multiple times. Such a shear wave observation method is called an interleaving method. This will be referred to as Fig.10 Describe in detail.

[0116] In addition, the controller 300 may generate a second ultrasonic image based on the second ultrasonic echo signal. That is, the second ultrasonic image may be defined as a shear wave photographed image.

[0117] The controller 300 of the ultrasonic diagnostic apparatus 1 may detect the displacement of the tissue at a plurality of sampling points in the ROI (430). Specifically, the controller 300 may set a plurality of transmission scan lines so that a plurality of tracking pulses are transmitted to different positions, and detect the displacement of the tissue at a plurality of sampling points corresponding to the plurality of transmission scan lines. For example, the controller 300 may detect the displacement of the tissue by performing cross-correlation on the first ultrasonic image (as a reference ultrasonic image) and the second ultrasonic image (as a shear wave captured image).

[0118] The controller 300 may estimate the time when the shear wave reaches the tissue based on the displacement of the tissue (440). In detail, the controller 300 may estimate the time point when the displacement of the tissue is maximum as the shear wave arrival time. The controller 300 may estimate the shear wave arrival time for each sampling point among the plurality of sampling points.

[0119] The controller 300 may estimate the shear wave velocity based on the distances between the plurality of sampling points and the shear wave arrival times (450). For example, the controller 300 may calculate the shear wave velocity using the distance between two sampling points located in the traveling direction of the shear wave and the shear wave arrival times of the two sampling points.

[0120] Hereinafter, the method of estimating the shear wave velocity will be described in more detail.

[0121] Figure 6 The induction of shear waves by a push pulse is shown. Figure 7 The propagation of shear waves is shown.

[0122] Reference Figure 6 , the ultrasound probe 100 may emit a push pulse 521 along a push line in the depth direction (Z direction) under the control of the ultrasound diagnostic apparatus 1. The push pulse may be radiated to a focus 520 in the ROI to cause displacement of tissue and induce a shear wave 530. The push pulse is a focused beam with a relatively high focus, and may have beam profiles 521a and 521b of narrow width.

[0123] When the push pulse 521 is emitted to the focus 520 in the ROI, a shear wave 530 may be induced. That is, when a force is applied to the tissue of the focus 520 in the depth direction (Z direction) by the push pulse 521, the tissue of the focus 520 moves in the depth direction (Z direction). The distance moved by the tissue in the depth direction (Z direction) may be defined as displacement. Since the tissue of the object has a certain degree of elasticity and adjacent tissues are organically connected, the movement of the tissue at the focus 520 also affects the adjacent tissues.

[0124] Reference Figure 7 , the movement of the tissue at the focus 520 causes displacement of the adjacent tissue. Due to the displacement of the tissue, the shear wave 530 may propagate in the X direction (a direction perpendicular to the depth direction (Z direction)). The shear wave 530 propagates to both sides from the focus 520 of the push pulse 521. The shear wave 530 changes its velocity according to the vibration characteristics of the medium. Therefore, the elasticity of the tissue can be obtained by estimating the shear wave velocity.

[0125] Figure 8 An example of a method of detecting shear waves is shown. Fig. 9 The emission of tracking pulses according to another example of a method of detecting shear waves is shown.

[0126] Reference Figure 8 , the ultrasound probe 100 may transmit a tracking pulse 540 having wide beam profiles 540a and 540b to a ROI 550 in which a shear wave 530 propagates due to displacement of the tissue, and receive an ultrasound echo signal as a result of the tracking pulse 540 being reflected from the ROI 550. The ultrasound diagnostic apparatus 1 may detect the displacement of the tissue based on the echo signal of the tracking pulse 540.

[0127] For example, the controller 300 may detect the displacement of the tissue by performing cross-correlation on the first ultrasonic image as a reference ultrasonic image and the second ultrasonic image as a shear wave captured image. In other words, the controller 300 may compare the first ultrasonic image (reference ultrasonic image) before applying the push pulse 521 with the second ultrasonic image (shear wave captured image) after applying the push pulse 521, thereby detecting the degree of tissue movement.

[0128] In addition, the controller 300 may acquire shear wave captured images at a high frame rate and compare consecutive shear wave captured image frames to detect displacement of tissue.

[0129] However, when using shear waves to measure the elasticity of tissue, it is necessary to accurately observe the propagation of shear waves in order to accurately obtain the elasticity. Figure 8As shown in FIG. 5 , when the beam profiles 540 a and 540 b of the tracking pulse 540 are wide, the observation region is made wide, and thus uniform observation of the ROI 550 can be performed, but observation performance (eg, signal-to-noise ratio (SNR)) is degraded. Figure 8 The tracking pulse 540 shown in FIG. 5 is defined as a wide focused transmit beam (Wide Focused Transmit Tx Beam).

[0130] Furthermore, when using tracking pulses 540 with wide beam profiles 540a and 540b, elasticity may not be accurately measured in an environment where reverberation exists. That is, since a transmit beam with a large width may include many interferences, the accuracy of elasticity measurement may be reduced.

[0131] like Fig. 9 As shown in , when using tracking pulses Tx1 with narrow beam profiles 560a and 560b, a relatively high SNR can be achieved. Fig. 9 The tracking pulse Tx1 shown in FIG. 5 can be defined as a tightly focused transmit beam (tightly focused Tx beam). Using a narrow transmit beam can improve the accuracy of elasticity measurement even in an environment with reverberation. However, the tracking pulse Tx1 with narrow beam profiles 560a and 560b results in a narrowed observation area. Therefore, in order to widen the observation area of ​​the tracking pulse Tx1, an interleaving or interrogation scheme is used.

[0132] A tightly focused tracking pulse Tx1 is emitted into the ROI. The position of the focus to which the tracking pulse Tx1 is emitted may be adjusted based on the ROI. That is, the focus of the tracking pulse Tx1 may be moved into the ROI in response to the movement of the ROI. At least one of the depth (Z direction) and the lateral (X direction) position of the focus of the tracking pulse Tx1 may be adjusted.

[0133] The beam profiles 560a and 560b of the tightly focused tracking pulse Tx1 are set to be smaller than the width of the ROI. Fig. 9 As shown in , the beam width of the tracking pulse Tx1 in the X direction at the focus is set to be smaller than the width of the ROI.

[0134] Fig.10 A method of transmitting multiple tracking pulses to widen the observation area is shown.

[0135] Reference Fig.10 In the left figure of FIG. 5 , in order to widen the observation area of ​​the tracking pulse Tx1 having the narrow beam profiles 560a and 560b, a plurality of tracking pulses Tx1, Tx2, Tx3, and Tx4 may be sequentially transmitted to a plurality of positions and / or focal points in the ROI. That is, after transmitting a push pulse 520 along the push line 521, a plurality of tracking pulses Tx1, Tx2, Tx3, and Tx4 may be sequentially transmitted along each transmission scan line.

[0136] Before transmitting the plurality of tracking pulses Tx1, Tx2, Tx3, and Tx4 to the ROI, the position of the focus of each of the plurality of tracking pulses Tx1, Tx2, Tx3, and Tx4 is adjusted to be included in the ROI. In addition, the position of the focus of each of the plurality of tracking pulses Tx1, Tx2, Tx3, and Tx4 may be adjusted so that the focus is moved into the ROI according to the movement of the ROI. Since the position of the focus of each of the plurality of tracking pulses Tx1, Tx2, Tx3, and Tx4 is adjusted in response to the movement of the ROI, the accuracy of shear wave observation may be improved.

[0137] The controller 300 of the ultrasonic diagnostic apparatus 1 performs sampling on the echo signal of each tracking pulse of the plurality of tracking pulses Tx1, Tx2, Tx3 and Tx4. In addition, interpolation may be performed to increase the sampling rate. Such a shear wave observation method is called an interleaved method because the sampling is interleaved in time.

[0138] On the other hand, as the number of interleavings increases, the observation area becomes wider and the error in estimating shear wave velocity and elasticity decreases. Fig.10 In FIG. 4 , four interleaving operations are performed. That is, Fig.10 The transmission of four tracking pulses is shown.

[0139] In addition, refer to Fig.10 As shown in the right figure of , a plurality of push pulses 520 may be sequentially emitted along the push line 521. The plurality of push pulses 520 may be emitted to the same focus or to positions at different depths on the push line 521. In addition, a plurality of tracking pulses Tx1, Tx2, Tx3, and Tx4 may be sequentially emitted to correspond to the respective push pulses 520. In other words, the ultrasonic diagnostic apparatus 1 may emit a first push pulse and emit a first tracking pulse Tx1 to observe shear waves, emit a second push pulse and emit a second tracking pulse Tx2 to observe shear waves, emit a third push pulse and emit a third tracking pulse Tx3 to observe shear waves, and then emit a fourth push pulse and emit a fourth tracking pulse Tx4 to observe shear waves. Such a shear wave observation method is called an interrogation method.

[0140] As described above, even if a tracking pulse having a narrow beam profile is used, the observable area can be widened by sequentially transmitting a plurality of tracking pulses Tx1 , Tx2 , Tx3 , and Tx4 to a plurality of points in the ROI.

[0141] Fig.11 The radial emission of multiple tracking pulses is shown to suit the region of interest.

[0142] Reference Fig.11, the controller 300 of the ultrasonic diagnostic apparatus 1 may set the ROI 550 to a radial shape, a fan shape, or a trapezoidal shape. The controller 300 may control the ultrasonic probe 100 to transmit a plurality of tracking pulses Tx1, Tx2, Tx3, and Tx4 in a radial direction, thereby corresponding to the radially formed ROI 550. That is, the controller 300 may control the transducer array 110 to transmit a plurality of tracking pulses Tx1, Tx2, Tx3, and Tx4 in a radial direction.

[0143] When the ultrasound probe 100 is convex, the transducer array 110 may be formed as a curved surface. Therefore, with the convex transducer array 110, a plurality of tracking pulses Tx1, Tx2, Tx3, and Tx4 may be transmitted in a radial shape. The controller 300 may selectively activate transducer elements included in the transducer array 110. The controller 300 may activate different transducer elements to transmit a plurality of tracking pulses Tx1, Tx2, Tx3, and Tx4.

[0144] ROI 550 may be set to have various sizes or widths. The user may set ROI 550 using control panel 260. In addition, as the depth of ultrasound irradiation increases, the size or width of ROI 550 may be set larger. Controller 300 may set the intervals between the plurality of tracking pulses Tx1, Tx2, Tx3, and Tx4 to correspond to the set ROI 550. In addition, controller 300 may set the emission angles of the plurality of tracking pulses Tx1, Tx2, Tx3, and Tx4 to correspond to ROI 550.

[0145] Will refer to Fig.24 and Fig.25 Description: Set the intervals between multiple tracking pulses Tx1, Tx2, Tx3, and Tx4.

[0146] Fig.12 Multiple receive scan lines corresponding to a single tracking pulse are shown.

[0147] Reference Fig.12 , the controller 300 of the ultrasonic diagnostic apparatus 1 may set a plurality of reception scanning lines Rx1-1, Rx1-2, Rx1-3, and Rx1-4 corresponding to the first tracking pulse Tx1. Fig.12 , four receiving scanning lines Rx1-1, Rx1-2, Rx1-3 and Rx1-4 are shown. Generally, the distance d between the multiple receiving scanning lines Rx1-1, Rx1-2, Rx1-3 and Rx1-4 is set to be constant.

[0148] The first tracking pulse Tx1 has beam profiles 560a and 560b of a predetermined width, and transmits the beam to a position corresponding to four multi-receiving scan lines Rx1-1, Rx1-2, Rx1-3, and Rx1-4. The transducer array 110 of the ultrasound probe 100 can receive ultrasound echo signals through the four receiving scan lines Rx1-1, Rx1-2, Rx1-3, and Rx1-4. The controller 300 can appropriately delay and sum the ultrasound echo signals received through the four receiving scan lines Rx1-1, Rx1-2, Rx1-3, and Rx1-4.

[0149] Beamforming using such multiple receive scan lines can reduce ultrasound image acquisition time and increase the frame rate of ultrasound images. Shear waves decay rapidly while propagating along tissues, and therefore travel a short distance in a short time. Therefore, by sampling ultrasound echo signals received through multiple receive scan lines, shear waves can be easily observed.

[0150] On the other hand, increasing the number of receive scan lines can be seen as a method of increasing the sampling points. However, setting a large number of receive scan lines in response to a single tracking pulse can increase the width of the transmit beam. Figure 8 As described, when the width of the transmit beam is wide, a large amount of interference may be included, which may reduce the SNR and degrade the accuracy of the elasticity measurement.

[0151] Fig.13 A sequence of sets of multiple tracking pulses and multiple receive scan lines is shown.

[0152] Reference Fig.13 , shows a sequence of multiple receiving scan lines corresponding to each of the four tracking pulses Tx1, Tx2, Tx3, and Tx4. The controller 300 may set sets B1, B2, B3, and B4 of the multiple receiving scan lines to correspond to the multiple corresponding tracking pulses. Specifically, the controller 300 may set a first set B1 of the first receiving scan line Rx1-1, the second receiving scan line Rx1-2, the third receiving scan line Rx1-3, and the fourth receiving scan line Rx1-4 corresponding to the first tracking pulse Tx1. In addition, the controller 300 may set a second set B2 of the fifth receiving scan line Rx2-1, the sixth receiving scan line Rx2-2, the seventh receiving scan line Rx2-3, and the eighth receiving scan line Rx2-4 corresponding to the second tracking pulse Tx2. Similarly, the controller 300 may set a third set B3 of multiple receiving lines and a fourth set B4 of multiple receiving lines corresponding to the third tracking pulse Tx3 and the fourth tracking pulse Tx4, respectively.

[0153] Referring to the first receiving scan line Rx1-1 (as an example of the receiving scan line of the set B1 corresponding to the first tracking pulse Tx1), the first receiving scan line Rx1-1 and the second receiving scan line Rx1-2 are arranged on the left side of the first tracking pulse Tx1, and the third receiving scan line Rx1-3 and the fourth receiving scan line Rx1-4 are arranged on the right side of the first tracking pulse Tx1.

[0154] Typically, the distance d between the multiple reception scan lines Rx1-1, Rx1-2, Rx1-3, and Rx1-4 included in the same set is set to be constant. In addition, the distance d between adjacent sets of multiple reception scan lines is also set to be constant. For example, the distance d between the fourth reception scan line Rx1-4 and the fifth reception scan line Rx2-1 is set to be constant.

[0155] The ultrasonic probe 100 can induce a shear wave 530 by transmitting a push pulse to a focus 520 in a depth direction (Z direction). Since the shear wave 530 travels in an X direction perpendicular to the depth direction (Z direction), the ultrasonic probe 100 can transmit a first tracking pulse Tx1 to a fourth tracking pulse Tx4 along the X direction. When the shear wave is observed using an interleaved method, a transmit beam generated by a plurality of tracking pulses Tx1, Tx2, Tx3, and Tx4 is sequentially transmitted to the positions of a plurality of receiving scan lines Rx1-1 to Rx4-4. The ultrasonic probe 100 can receive an ultrasonic echo signal as a result of reflection of the plurality of tracking pulses Tx1, Tx2, Tx3, and Tx4 along a plurality of receiving scan lines of a set B1, B2, B3, and B4.

[0156] The shear wave 530 sequentially reaches the positions of the plurality of reception scan lines Rx1-1 to Rx4-4. The controller 300 may detect the displacement of the tissue corresponding to the position of the reception scan line based on the ultrasonic echo signals received along the plurality of reception scan lines Rx1-1 to Rx4-4. The controller 300 may detect the displacement of the tissue at a plurality of sampling points for each of the plurality of reception scan lines Rx1-1 to Rx4-4.

[0157] In addition, the controller 300 can estimate the arrival time of the shear wave 530 on each of the reception scan lines Rx1-1 to Rx4-4 based on the displacement of the tissue. The controller 300 can estimate the speed of the shear wave based on the distance between the reception scan lines and the difference between the arrival times of the shear wave on the reception scan lines.

[0158] For example, the controller 300 may detect the displacement of the tissue at multiple sampling points of the first receiving scan line Rx1-1 and estimate the arrival time of the shear wave 530. Similarly, the controller 300 may detect the displacement of the tissue at multiple sampling points of the second receiving scan line Rx1-2 and estimate the arrival time of the shear wave 530. Subsequently, the controller 300 may estimate the speed of the shear wave 530 based on the distance d between the first receiving scan line Rx1-1 and the second receiving scan line Rx1-2 and the arrival time of the shear wave on each of the first receiving scan line Rx1-1 and the second receiving scan line Rx1-2.

[0159] On the other hand, the distance d between the first reception scan line Rx1-1 and the second reception scan line Rx1-2 may refer to a distance d between a first sampling point of the first reception scan line Rx1-1 and a second sampling point of the second reception scan line Rx1-2 located at the same depth.

[0160] Fig.14 The relationship between the displacement of the tissue and the arrival time of the shear wave is shown.

[0161] Reference Fig.14 , the displacement of the tissue corresponding to the first sampling point of the first receiving scan line Rx1-1 is maximum at time t1. Therefore, the first shear wave arrival time for the first sampling point of the first receiving scan line Rx1-1 can be determined as t1. Similarly, the displacement of the tissue corresponding to the second sampling point of the second receiving scan line Rx1-2 is maximum at time t2. Therefore, the second shear wave arrival time for the second sampling point of the second receiving scan line Rx1-2 can be determined as t2.

[0162] Fig.15 The position error of multiple receive scan lines is shown.

[0163] Reference Fig.15 It can be seen that there is a difference between the ideal position and the actual position of the multiple receiving scan lines (the first receiving scan line Rx1-1 to the fourth receiving scan line Rx1-4) corresponding to the first tracking pulse Tx1.

[0164] As described above, the controller 300 arranges the first to fourth receiving scan lines Rx1-1 to Rx1-4 on both sides of the first tracking pulse Tx1, and sets the distance d between two adjacent receiving scan lines among the first to fourth receiving scan lines Rx1-1 to Rx1-4 to be constant. However, since the beam of the first tracking pulse Tx1 is tightly focused, a position error occurs between the set multi-receiving scan lines (dashed lines) and the actual multi-receiving scan lines (solid lines).

[0165] Specifically, the multiple reception scan lines actually generated tend to gather around the tracking pulse Tx1. The first reception scan line Rx1-1 and the second reception scan line Rx1-2 are generated at positions offset to the right from the set position. The third reception scan line Rx1-3 and the fourth reception scan line Rx1-4 are generated at positions offset to the left from the set position. Therefore, an error occurs between the distance d between the set first reception scan line Rx1-1 and the set second reception scan line Rx1-2 and the distance de between the actual first reception scan line Rx1-1 and the actual second reception scan line Rx1-2. The position error of the reception scan line increases as it moves away from the tracking pulse Tx1.

[0166] The prior art estimates the velocity of shear waves using the entire sampling points of multiple receiving scan lines without considering the position error of the receiving scan lines, thus resulting in errors in the estimated shear wave velocity.

[0167] Fig.16 The error in the shear wave arrival time for each of the multiple receive scan lines is shown.

[0168] Reference Fig.16 , shows a wavefront diagram of the arrival time of the shear wave measured in a plurality of receiving scan lines Rx1 - 1 to Rx4 - 4 . Fig.16 The time points when the shear wave reaches each sampling point of the plurality of reception scan lines Rx1-1 to Rx4-4 are shown. The numerical values ​​shown in the wavefront diagram are for illustrative purposes only and are not limited thereto.

[0169] As described above, when a tightly focused transmit beam is used, position errors of the receive scan lines may occur, and thus errors in the shear wave arrival times with respect to the plurality of receive scan lines Rx1-1 to Rx4-4 may also occur.

[0170] exist Fig.16 , the shear wave arrival time of the first receiving scan line Rx1-1 to the fifth receiving scan line Rx2-1 is described. With reference to the sampling point at a depth of -44 mm, the first shear wave arrival time of the first sampling point of the first receiving scan line Rx1-1 is approximately 3.4 ms, the second shear wave arrival time of the second sampling point of the second receiving scan line Rx1-2 is approximately 3.6 ms, the third shear wave arrival time of the third sampling point of the third receiving scan line Rx1-3 is approximately 3.75 ms, the fourth shear wave arrival time of the fourth sampling point of the fourth receiving scan line Rx1-4 is approximately 4.1 ms, and the fifth shear wave arrival time of the fifth sampling point of the fifth receiving scan line Rx2-1 is approximately 4.5 ms.

[0171] In addition, the difference ta1 between the arrival time of the first shear wave and the arrival time of the second shear wave is 0.2ms, the difference ta2 between the arrival time of the second shear wave and the arrival time of the third shear wave is 0.15ms, the difference ta3 between the arrival time of the third shear wave and the arrival time of the fourth shear wave is 0.35ms, and the difference ta4 between the arrival time of the fourth shear wave and the arrival time of the fifth shear wave is 0.4ms. Thus, it can be seen that a position error of the received scan line has occurred.

[0172] Various methods may be used to estimate the shear wave velocity. As an example, the velocity of the shear wave may be estimated based on the distance between the first sampling point and the second sampling point and the difference between the first shear wave arrival time and the second shear wave arrival time. As another example, the velocity of the shear wave may be estimated for each of a plurality of sampling points using a plane equation or a wave equation, and the velocities of the shear waves for all sampling points may be accumulated and averaged.

[0173] However, conventional shear wave velocity estimation methods that reflect the values ​​of all scan lines and sampling points have difficulty removing the error of shear wave velocity caused by the position error of the received scan line. Therefore, the reliability of the estimation result of shear wave velocity is very low.

[0174] Hereinafter, a method of estimating shear wave velocity that can remove position errors of reception scan lines will be described. According to the present disclosure, shear wave velocity can be accurately obtained by selectively performing signal processing on multiple reception scan lines. Signal processing may refer to processing for ultrasound echo signals.

[0175] Fig.17 Receive scan lines in a set of multiple receive scan lines that are located at the same relative position are shown. Fig.18 The shear wave arrival times are shown for receive scan lines located at the same relative positions.

[0176] Reference Fig.17 , when it is assumed that a plurality of tracking pulses Tx1, Tx2, Tx3, and Tx4 are transmitted at a constant interval 4d, the intervals between the plurality of reception scan lines may also be set to a constant interval d. In addition, the positions of the reception scan lines actually generated may be different from the positions of the reception scan lines set as described above. Therefore, the distance de between the plurality of reception scan lines actually generated may be different from the distance d between the plurality of set reception scan lines.

[0177] However, the distance 4d between the receiving scan lines located at the same relative position in each of the sets B1, B2, B3 and B4 of multiple receiving scan lines can be constant. For example, the distance between the first receiving scan line Rx1-1 and the fifth receiving scan Rx2-1 is 4d. Since the first receiving scan line Rx1-1 and the fifth receiving scan Rx2-1 have position errors caused by the first tracking pulse Tx1 and the second tracking pulse Tx2, respectively, the first receiving scan line Rx1-1 and the fifth receiving scan Rx2-1 have the same relative position. In other words, since the first receiving scan line Rx1-1 is a receiving scan line arranged at the first position in the first set B1, and the fifth receiving scan line Rx2-1 is a receiving scan line arranged at the first position in the second set B2, the first receiving scan line Rx1-1 and the second receiving scan line Rx1-2 can be considered to have the same relative position. Similarly, the second receiving scan line Rx1-2 and the sixth receiving scan line Rx2-2 also exist at the same relative position.

[0178] Fig.18 It is shown from Fig.16 In other words, Fig.18 Arrival times of shear waves regarding the first receiving scan line Rx1-1, the fifth receiving scan line Rx2, the ninth receiving scan line Rx3-1 and the thirteenth receiving scan line Rx4-1 (which are receiving scan lines arranged at respective first positions in the set of multiple receiving scan lines B1, B2, B3 and B4) are shown.

[0179] Reference Fig.18 For the sampling points located at a depth of -44 mm, the arrival time of the first shear wave at the first sampling point of the first receiving scan line Rx1-1 is approximately 3.2 ms, the arrival time of the fifth shear wave at the fifth sampling point of the fifth receiving scan line Rx2-1 is approximately 4.2 ms, the arrival time of the ninth shear wave at the ninth sampling point of the ninth receiving scan line Rx3-1 is approximately 5.2 ms, and the arrival time of the thirteenth shear wave at the thirteenth sampling point of the thirteenth receiving scan line Rx4-1 is approximately 6.2 ms.

[0180] In addition, the difference tb1 between the arrival time of the first shear wave and the arrival time of the fifth shear wave is 1ms, the difference tb2 between the arrival time of the fifth shear wave and the arrival time of the ninth shear wave is 1ms, and the difference tb3 between the arrival time of the ninth shear wave and the arrival time of the thirteenth shear wave is 1ms. That is, it can be seen that the differences between the shear wave arrival times of the receiving scan lines at the same relative position are the same.

[0181] In this way, the ultrasonic diagnostic apparatus 1 can remove the error of the shear wave velocity caused by the position error of the reception scan line by estimating the shear wave velocity using the shear wave arrival time with respect to the reception scan line at the same relative position.

[0182] Fig.19 is a flowchart showing a method of controlling an ultrasonic diagnostic apparatus, which describes a method of estimating shear wave velocity by grouping reception scan lines. Fig. 20 Shown is a diagram for describing Fig.19 Wavefront diagram of the method for estimating shear wave velocity shown in .

[0183] Reference Fig.19 , the controller 300 of the ultrasonic diagnostic apparatus 1 may control the ultrasonic probe 100. The ultrasonic probe 100 transmits a push pulse to the ROI of the object to induce a shear wave (1710). Thereafter, the ultrasonic probe 100 transmits a plurality of tracking pulses Tx1, Tx2, Tx3, and Tx4 for observing the shear wave to the ROI of the object (1720). In this case, the intervals between the plurality of tracking pulses Tx1, Tx2, Tx3, and Tx4 may be adjusted based on the ROI.

[0184] The ultrasound probe 100 receives ultrasound echo signals reflected from the ROI along sets B1, B2, B3, and B4 of multiple reception scan lines, each of which corresponds to a respective one of the plurality of tracking pulses (1730).

[0185] The controller 300 of the ultrasonic diagnostic apparatus 1 may detect the displacement of the tissue at a plurality of sampling points of each of the plurality of reception scan lines Rx1-1 to Rx4-4 (1740). In addition, the controller 300 may estimate a time point when the shear wave reaches the plurality of sampling points of each of the plurality of reception scan lines Rx1-1 to Rx4-4 (1750). Fig. 20 The time points when the shear wave reaches a plurality of sampling points of each of the reception scan lines Rx1 - 1 to Rx4 - 4 are shown.

[0186] The controller 300 may group the reception scan lines arranged at the same relative position in each set of the multiple reception scan lines and generate a plurality of groups (1760 and 2010). Fig. 20 , the first receiving scan line Rx1-1, the fifth receiving scan line Rx2-1, the ninth receiving scan line Rx3-1 and the thirteenth receiving scan line Rx4-1 are set as the first group. In addition, the second receiving scan line Rx1-2, the sixth receiving scan line Rx2-2, the tenth receiving scan line Rx3-2 and the fourteenth receiving scan line Rx4-2 are set as the second group.

[0187] The third receiving scan line Rx1-3, the seventh receiving scan line Rx2-3, the eleventh receiving scan line Rx3-3 and the fifteenth receiving scan line Rx4-3 are set as the third group, and the fourth receiving scan line Rx1-4, the eighth receiving scan line Rx2-4, the twelfth receiving scan line Rx3-4 and the sixteenth receiving scan line Rx4-4 are set as the fourth group.

[0188] The controller 300 may estimate a plurality of shear wave velocities each corresponding to one of the groups (1770). The controller 300 may estimate a first shear wave velocity of the first group, a second shear wave velocity of the second group, a third shear wave velocity of the third group, and a fourth shear wave velocity of the fourth group.

[0189] For example, in the case of the first group, the controller 300 may calculate the first shear wave velocity using the distance between the first sampling point of the first receiving scan line Rx1-1 and the fifth sampling point of the fifth receiving scan line Rx2-1 and the difference between the shear wave arrival times for the first sampling point and the fifth sampling point. The controller 300 may calculate the first shear wave velocity using the sampling points of the first receiving scan line Rx1-1, the fifth receiving scan line Rx2-1, the ninth receiving scan line Rx3-1, and the thirteenth receiving scan line Rx4-1 included in the first group.

[0190] On the other hand, the controller 300 may calculate the shear wave velocity for each of the plurality of sampling points included in the first group using a plane equation or a wave equation, and calculate the first shear wave velocity by summing and averaging the shear wave velocities. The controller 300 may calculate the shear wave velocity for each group in various ways.

[0191] The controller 300 may combine the shear wave velocities of the respective groups to obtain a final shear wave velocity (1780 and 2020). In detail, the controller 300 may combine the plurality of shear wave velocities v i The average value of the final shear wave velocity v final , as shown in Formula 1.

[0192] [Formula 1]

[0193]

[0194] In addition, the controller 30 may use the shear wave velocity v i The reliability measurement index (RMI) of each shear wave velocity in i The final shear wave velocity v is determined by the weighted average of final , as shown in Formula 2 below.

[0195] [Formula 2]

[0196]

[0197] On the other hand, RMI regarding shear wave velocity can be obtained by combining uniformity of shear wave propagation, magnitude of shear wave displacement, correlation of shear wave shape, etc. In addition, RMI can be calculated by various known methods.

[0198] For example, the controller 300 may calculate the first shear wave velocity of the first group in two different methods, and determine the RMI for the first shear wave velocity based on the ratio of the first shear wave velocities calculated by the two different methods. Specifically, the controller 300 may calculate the 1-1 shear wave velocity using the following values: a value obtained by averaging the distances from the focus 520 to which the push pulse is emitted to each receiving scan line included in the first group, and a value obtained by averaging the shear wave arrival times with respect to each receiving scan line included in the first group. In addition, as described above, the controller 300 may calculate the 1-2 shear wave velocity using the first receiving scan line Rx1-1 and the fifth receiving scan line Rx2-1. The controller 300 may calculate the first shear wave velocity ratio SWV_ratio by dividing the difference between the 1-1 shear wave velocity and the 1-2 shear wave velocity by the 1-1 shear wave velocity. The controller 300 may determine the RMI of the first shear wave velocity based on the first shear wave velocity ratio SWV_ratio.

[0199] On the other hand, when the shear wave velocity ratio SWV_ratio has a value greater than or equal to 0 and less than 0.5, the controller 300 may determine the value of RMI to 1. When the value of the shear wave velocity ratio SWV_ratio is greater than or equal to 0.5, the controller 300 may determine the value of RMI by Equation 3 below.

[0200] [Formula 3]

[0201] RMI=-2×SWV_ratio+2

[0202] The controller 300 can calculate the elasticity of the tissue in the ROI based on the final shear wave velocity and generate a shear wave elasticity image. The controller 300 can control the display 270 to output the shear wave elasticity image. The shear wave elasticity image can be displayed as overlapping or aligned with a reference ultrasound image. The reference ultrasound image can be a B-mode image. In addition, the controller 300 can control the display 270 to display elasticity, depth, and RMI.

[0203] Fig.21 is a flowchart illustrating a method of controlling an ultrasonic diagnostic apparatus according to another embodiment, which describes a method of estimating shear wave velocity by selecting some reception scan lines. Fig. 22 and Fig.23 Shown is a diagram for describing Fig.21 Wavefront diagram of the method for estimating shear wave velocity shown in .

[0204] Reference Fig.21 , the ultrasound probe 100 transmits a push pulse to the ROI of the object to induce a shear wave (1810), and transmits a plurality of tracking pulses Tx1, Tx2, Tx3, and Tx4 for observing the shear wave to the ROI of the object (1820). In this case, the intervals between the plurality of tracking pulses Tx1, Tx2, Tx3, and Tx4 may be adjusted based on the ROI.

[0205] The ultrasound probe 100 receives ultrasound echo signals reflected from the ROI along sets B1, B2, B3, and B4 of multiple reception scan lines, each of which corresponds to a corresponding one of multiple tracking pulses (1830). The controller 300 may detect the displacement of the tissue at multiple sampling points of each of the multiple reception scan lines Rx1-1 to Rx4-4 (1840). In addition, the controller 300 may estimate a time point when the shear wave reaches the multiple sampling points of each of the multiple reception scan lines Rx1-1 to Rx4-4 (1850).

[0206] The controller 300 may select some of the multiple reception scan lines and estimate the shear wave velocity based on the ultrasound echo signals received along the selected reception scan lines. The controller 300 may select the reception scan lines (1860, 2110, and 2210) based on a predetermined selection type.

[0207] Reference Fig. 22 As a first selection type, the controller 300 may select a reception scan line adjacent to the plurality of tracking pulses Tx1, Tx2, Tx3, and Tx4 from among the plurality of reception scan line sets B1, B2, B3, and B4. Since each of the plurality of tracking pulses Tx1, Tx2, Tx3, and Tx4 forms a transmission beam, the controller 300 may select a reception scan line adjacent to the center of the transmission beam.

[0208] like Fig. 22 As shown in the figure, the second receiving scan line Rx1-2 and the third receiving scan line Rx1-3 adjacent to the center of the transmitting beam of the first tracking pulse Tx1 are selected, the sixth receiving scan line Rx2-2 and the seventh receiving scan line Rx2-3 adjacent to the center of the transmitting beam of the second tracking pulse Tx2 are selected, the tenth receiving scan line Rx3-2 and the eleventh receiving scan line Rx3-3 adjacent to the center of the transmitting beam of the third tracking pulse Tx3 are selected, and the fourteenth receiving scan line Rx4-2 and the fifteenth receiving scan line Rx4-3 adjacent to the center of the transmitting beam of the fourth tracking pulse Tx4 are selected.

[0209] like Fig.15As shown in , since the receiving scan line adjacent to the tracking pulse has a small position error, the receiving scan line adjacent to the tracking pulse is selected, thereby reducing the error of the final shear wave velocity.

[0210] Reference Fig.23 As a second selection type, the controller 300 may select reception scan lines other than the reception scan line with the minimum shear wave arrival time and the reception scan line with the maximum shear wave arrival time. Fig.23 In the wavefront diagram of FIG. 1 , the receiving scan line having the minimum shear wave arrival time is the first receiving scan line Rx1-1, and the receiving scan line having the maximum shear wave arrival time is the sixteenth receiving scan line Rx4-4. Considering that the position of the receiving scan line is shifted toward the center due to the transmission beam energy of the multiple tracking pulses Tx1, Tx2, Tx3, and Tx4, the position of the outermost receiving scan line in the sequence of the multiple receiving scan lines may have the largest error.

[0211] Furthermore, as a third selection type (not shown), the controller 300 may select a reception scan line having a position error smaller than a predetermined value.

[0212] The controller 300 may estimate a final shear wave velocity based on the shear wave arrival times associated with the selected receive scan lines (1870, 2120, and 2220).

[0213] In addition, Fig.21 , Fig. 22 and Fig.23 The shear wave velocity estimation method described in ref. Fig.19 and Fig. 20 That is, the selected reception scan lines may be set into a plurality of groups, and the shear wave velocity may be estimated for each group.

[0214] Fig.24 and Fig.25 The intervals between multiple tracking pulses are shown.

[0215] Reference Fig.24 , shows a beam profile diagram of a plurality of tracking pulses Tx1, Tx2, Tx3, and Tx4. The controller 300 may set the intervals W1 and W2 between the plurality of tracking pulses Tx1, Tx2, Tx3, and Tx4 to be narrow so that a flat region (region greater than -3dB) of the transmission beams of the plurality of tracking pulses Tx1, Tx2, Tx3, and Tx4 is used. When observing a narrow ROI, the narrow setting of the intervals w1 and w2 between the plurality of tracking pulses Tx1, Tx2, Tx3, and Tx4 may be applied.

[0216] In this case, since the multiple receiving scan lines Rx1, Rx2, Rx3, and Rx4 corresponding to each of the multiple tracking pulses Tx1, Tx2, Tx3, and Tx4 are set to match the flat area (area greater than -3dB) of the transmission beam, the interval between the receiving scan lines can be set to be narrow. On the other hand, the interval between the receiving scan lines is set to be constant.

[0217] Reference Fig.25 , the controller 300 may set the intervals between the plurality of tracking pulses Tx1, Tx2, Tx3, and Tx4 to be greater than a predetermined interval (e.g., the intervals of the transmission beam at -3dB) to use the non-flat region (region less than -3dB) of the plurality of tracking pulses Tx1, Tx2, Tx3, and Tx4. Even in this case, the beam widths of the plurality of tracking pulses Tx1, Tx2, Tx3, and Tx4 are set closely. When observing a wide ROI, the wide setting of the intervals w1 and w2 between the plurality of tracking pulses Tx1, Tx2, Tx3, and Tx4 may be applied. The intervals between the plurality of tracking pulses may be set without deviating from the range ROI.

[0218] For example, in order to observe a shear wave greater than a predetermined amplitude in a ROI using four tracking pulses Tx1 , Tx2 , Tx3 , and Tx4 , the intervals between the four tracking pulses need to be set large.

[0219] In this case, the multiple receiving scan lines Rx1, Rx2, Rx3, and Rx4 corresponding to each of the multiple tracking pulses Tx1, Tx2, Tx3, and Tx4 are set to match the non-flat area (area less than -3dB) of the transmission beam, so the interval between the receiving scan lines can be set wide. In addition, Fig.25 The spacing between the received scan lines shown in Fig.24 The spacing between the received scan lines shown in .

[0220] Although not shown, the controller 300 may set intervals between the plurality of tracking pulses Tx1, Tx2, Tx3, and Tx4 to be different from each other. The plurality of tracking pulses Tx1, Tx2, Tx3, Tx4 are transmitted to the ROI based on a preset interval.

[0221] On the other hand, when Fig.25 When the interval between the plurality of tracking pulses is set to be greater than a predetermined interval as shown in Figures 19 to 23 That is, since the shear wave velocity estimation method according to the present disclosure selectively performs signal processing and / or data processing on multiple receiving scan lines, the error of shear wave velocity estimation can be reduced even when shear waves are observed for a wide ROI.

[0222] Fig.26 and Fig. 27 The results of elasticity measurements according to the prior art are shown. Fig.28 The results of elasticity measurement by the method of controlling the ultrasonic diagnostic apparatus according to the embodiment are shown.

[0223] Figure 26 to Figure 28 An ultrasound diagnostic image of a phantom including a liver and a fat layer is shown. In order to generate an environment in which reverberation occurs, a phantom with a 2 cm fat layer is used. On the other hand, the liver phantom has an elasticity value of 13 kPa to 14 kPa.

[0224] In order to compare the prior art and the present disclosure, the ROI 550 was set at a position where the depth of the phantom was approximately 4 cm to 6 cm, and the elasticity of the ROI 550 was measured.

[0225] Reference Fig.26 and Fig. 27 , the existing technology cannot properly measure the elasticity value in an environment with strong reverberation. Fig.26 In the test, the elasticity value was measured to be 23.7 kPa (see 2500). Fig. 27 In the example, the elasticity value measured is 34.2 kPa (see 2600). Thus, the reliability of the elasticity value measured by the prior art is very low.

[0226] On the other hand, refer to Fig.28 , it can be seen that even in an environment where reverberation occurs, the elasticity value measured according to the present disclosure has a high accuracy. That is, when the shear wave velocity estimation method according to the present disclosure is used, the measured elasticity value is 12.6 kPa (see 2700). The RMI value is calculated to be 0.5. Therefore, the elasticity value measured according to the present disclosure is significantly close to the elasticity value of the phantom, and the reliability is very high.

[0227] As described above, according to the disclosed ultrasonic diagnostic apparatus and control method, a tracking pulse having a narrow beam width can improve shear wave observation performance, and elasticity can be accurately measured even in an environment where reverberation occurs.

[0228] Furthermore, according to the disclosed ultrasonic diagnostic apparatus and control method, when the ROI is set wide, the interval between tracking pulses for shear wave observation is set wide, so that elasticity can be accurately measured.

[0229] Furthermore, according to the disclosed ultrasonic diagnostic apparatus and control method, the shear wave velocity can be accurately obtained by selectively performing signal processing on multiple reception scan lines for estimating the shear wave velocity.

[0230] In addition, the disclosed embodiments may be implemented in the form of a recording medium storing instructions executable by a computer. The instructions may be stored in the form of program code, and when executed by a processor, a program module may be generated to perform the operations of the disclosed embodiments. The recording medium may be implemented as a computer-readable recording medium.

[0231] The computer-readable recording medium includes all kinds of recording media in which instructions decodable by a computer are stored, for example, read-only memory (ROM), random access memory (RAM), magnetic tapes, magnetic disks, flash memories, optical data storage devices, and the like.

[0232] As is apparent from the above, the ultrasonic diagnostic apparatus and the control method thereof can improve the performance of shear wave observation and accurately measure elasticity by narrowing the beam width of the tracking pulse even in the presence of reverberation.

[0233] The ultrasonic diagnostic apparatus and the control method thereof can accurately measure elasticity by setting the interval of tracking pulses for shear wave observation to be wide when a region of interest (ROI) is set to be wide.

[0234] Furthermore, the ultrasonic diagnostic apparatus and the control method thereof can accurately measure elasticity by selectively performing signal processing on multiple reception scan lines for estimating shear wave velocity.

[0235] Although the embodiments of the present disclosure have been described for illustrative purposes, it will be appreciated by those skilled in the art that various modifications, additions and substitutions are possible without departing from the scope and spirit of the present disclosure. Therefore, the embodiments of the present disclosure are not described for limiting purposes.

Claims

1. A method for controlling an ultrasonic diagnostic device, the method comprising: transmitting a push pulse to a region of interest of a target object to induce a shear wave; adjusting the position of the focal point to which the plurality of tracking pulses are emitted based on the position of the region of interest; transmitting the plurality of tracking pulses to the region of interest; Setting a plurality of sets of receiving scan lines, each set corresponding to a corresponding one of the plurality of tracking pulses; In response to the plurality of tracking pulses, receiving ultrasound echo signals reflected from the region of interest along the plurality of receiving scan lines; estimating a shear wave velocity associated with the region of interest based on the ultrasound echo signals received along the multiple receive scan lines; generating a shear wave elasticity image based on the shear wave velocity; and outputting the shear wave elasticity image on a display, Wherein, estimating the shear wave velocity comprises at least one of the following operations: grouping reception scan lines located at the same relative position in each of the sets of the plurality of reception scan lines to generate a plurality of groups, estimating a plurality of shear wave velocities each corresponding to a respective one of the plurality of groups, and determining a final shear wave velocity based on the plurality of shear wave velocities; as well as Some reception scan lines are selected from the multiple reception scan lines based on a predetermined selection type, and shear wave velocity is estimated based on ultrasonic echo signals received along the selected some reception scan lines.

2. The method according to claim 1, further comprising setting the region of interest in a radial form, in, The step of transmitting the plurality of tracking pulses includes transmitting the plurality of tracking pulses radially to the region of interest in a radial form.

3. The method according to claim 1, wherein: The step of adjusting the position of the focus includes moving the focus into the region of interest in response to movement of the region of interest.

4. The method according to claim 1, wherein: The step of determining the final shear wave velocity includes determining an average value of the plurality of shear wave velocities or a weighted average value obtained by using a reliability measurement index on each of the plurality of shear wave velocities as the final shear wave velocity.

5. The method according to claim 1, wherein: The step of selecting a receiving scan line includes selecting a receiving scan line adjacent to each tracking pulse of the plurality of tracking pulses from the set of the plurality of receiving scan lines.

6. The method according to claim 1, wherein: The step of selecting a receiving scan line includes selecting a receiving scan line having a position error smaller than a predetermined value.

7. The method according to claim 1, wherein: The step of estimating the shear wave velocity further includes: estimating the arrival time of the shear wave on each of the multiple receiving scan lines, The step of selecting the receiving scan line includes: selecting the receiving scan line except the receiving scan line with the minimum arrival time of the shear wave and the receiving scan line with the maximum arrival time of the shear wave.

8. The method according to claim 1, wherein: The steps to estimate shear wave velocity include: detecting displacement of tissue at a plurality of sampling points of each of the plurality of receiving scan lines; estimating an arrival time of a shear wave on each of the multiple receive scan lines based on the displacement of the tissue; and The shear wave velocity is estimated based on the distances between the groups of reception scan lines and / or the selected reception scan lines and the differences between the arrival times of the shear waves on the groups of reception scan lines and / or the selected reception scan lines.

9. An ultrasonic diagnostic device comprising: an ultrasound probe configured to: transmit a push pulse to a region of interest of a target object, transmit a plurality of tracking pulses to the region of interest to observe shear waves induced by the push pulse, and receive ultrasound echo signals reflected from the region of interest in response to the plurality of tracking pulses; a controller configured to: adjust the position of the focus to which the plurality of tracking pulses are transmitted based on the position of the region of interest, estimate the shear wave velocity associated with the region of interest based on the ultrasound echo signal, and generate a shear wave elasticity image based on the shear wave velocity; as well as a display on which the shear wave elasticity image is output, wherein the controller is further configured to arrange a plurality of sets of receiving scan lines, each set corresponding to a respective one of the plurality of tracking pulses, and The controller is further configured to perform at least one of the following operations: grouping reception scan lines located at the same relative position in each of the sets of the plurality of reception scan lines to generate a plurality of groups, estimating a plurality of shear wave velocities each corresponding to a respective one of the plurality of groups, and determining a final shear wave velocity based on the plurality of shear wave velocities; and Some reception scan lines are selected from the multiple reception scan lines based on a predetermined selection type, and shear wave velocity is estimated based on ultrasonic echo signals received along the selected some reception scan lines.

10. The ultrasonic diagnostic apparatus according to claim 9, wherein: The controller sets the region of interest in a radial form, and controls the ultrasound probe to radially transmit the plurality of tracking pulses to the region of interest in a radial form.

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