Ultrasound diagnostic equipment, analysis equipment, and program

Abstract

To apply SWE even to an organ moving periodically.SOLUTION: An ultrasound diagnostic apparatus comprises a first calculation part and a second calculation part. The first calculation part, on the basis of first ultrasound information on the temporal deviation of an organ moving periodically, calculates a function on a clutter component from the organ. The second calculation part, on the basis of the function and second ultrasound information on the temporal deviation of the organ after the organ is pressurized, calculates a transverse wave propagating the organ with the pressure.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The embodiments disclosed in this specification and the drawings relate to an ultrasonic diagnostic apparatus, an analysis apparatus, and a program.

[0002] Conventionally, there is a technique called SWE (Shear Wave Elastography) that measures the hardness distribution of an organ of a subject using ultrasonic waves. In SWE, an ultrasonic diagnostic apparatus generates shear waves in an organ by applying pressure to the organ with ultrasonic waves. Then, the ultrasonic diagnostic apparatus estimates the hardness of each point of the organ by measuring the displacement caused by the shear waves propagating through the organ.

[0003] However, for an organ that moves periodically, such as the heart, it is difficult to measure the displacement of the shear wave caused by pressurization because the organ itself moves and causes displacement.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to make SWE applicable to an organ that moves periodically. However, the problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above problems. The problems corresponding to the respective effects of each configuration shown in the embodiments described later can also be regarded as other problems.

Means for Solving the Problems

[0006] The ultrasonic diagnostic apparatus according to the embodiment includes a first calculation unit and a second calculation unit. The first calculation unit is The heart before being pressurized by pulsed ultrasound. of ExerciseBased on the first ultrasonic information regarding displacement over time, This shows the temporal displacement caused by cardiac movement. The second calculation unit calculates a function relating to the clutter component. The second calculation unit calculates the function and the heart The above after pressurization heart of Exercise Based on the second ultrasonic information regarding the displacement over time, the pressurization is performed heart Calculate the transverse wave propagating through it. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a block diagram showing an example configuration of an ultrasound diagnostic device according to this embodiment. [Figure 2] Figure 2 is a graph showing an example of measurement results from an ultrasound diagnostic device. [Figure 3] Figure 3 shows an example of the sequence in which ultrasound is irradiated using an ultrasound diagnostic device. [Figure 4] Figure 4 shows an example of a method for calculating a function based on the first displacement information. [Figure 5] Figure 5 is an explanatory diagram illustrating an example of synchronization between the temporal displacement of an organ, represented by a function, and the displacement shown by the reflected wave data of the tracking pulse. [Figure 6] Figure 6 is an explanatory diagram illustrating an example of a method for calculating transverse waves based on second-order displacement information and a function. [Figure 7] Figure 7 shows an example of the measurement process performed by the ultrasound diagnostic device according to this embodiment. [Modes for carrying out the invention]

[0008] The following describes an embodiment of an ultrasonic diagnostic apparatus, an analysis apparatus, and a program with reference to the drawings. In the following embodiment, parts with the same reference numerals perform similar operations, and redundant explanations will be omitted as appropriate.

[0009] Figure 1 is a block diagram showing an example configuration of the ultrasound diagnostic apparatus 100 according to this embodiment. As shown in Figure 1, the ultrasound diagnostic apparatus 100 includes an ultrasound probe 101, an input interface 102, a display 103, and a main unit 104. The ultrasound probe 101, the input interface 102, and the display 103 are connected to the main unit 104 in a communicative manner.

[0010] The ultrasonic probe 101 has multiple piezoelectric transducers, which generate ultrasound based on drive signals supplied from the transmitting / receiving circuit 110 of the device body 104. The ultrasonic probe 101 also receives reflected waves from the subject P and converts them into electrical signals. For example, in SWE, the ultrasonic probe 101 emits pulsed ultrasound and receives reflected waves. The ultrasonic probe 101 is detachably connected to the device body 104.

[0011] When ultrasound is transmitted from the ultrasound probe 101 to the subject P, the transmitted ultrasound is reflected one after another by discontinuities in acoustic impedance within the subject P's internal tissues, and the reflected wave signals are received by multiple piezoelectric transducers on the ultrasound probe 101. The amplitude of the received reflected wave signals depends on the difference in acoustic impedance at the discontinuities where the ultrasound is reflected. When the transmitted ultrasound pulse is reflected by a moving blood flow or the surface of the heart wall, the reflected wave signal undergoes a frequency shift due to the Doppler effect, depending on the velocity component of the moving object relative to the ultrasound transmission direction.

[0012] The form of the ultrasound probe 101 is not particularly limited, and any form of ultrasound probe may be used. For example, the ultrasound probe 101 may be a 1D array probe that scans the subject P in two dimensions. Alternatively, the ultrasound probe 101 may be a mechanical 4D probe or a 2D array probe that scans the subject P in three dimensions.

[0013] The input interface 102 receives various instructions and information input operations from the operator. Specifically, the input interface 102 converts the input operations received from the operator into electrical signals and outputs them to the processing circuit 170 of the main unit 104. For example, the input interface 102 can be implemented by a trackball, switch buttons, mouse, keyboard, touchpad that performs input operations by touching the operating surface, touchscreen that integrates a display screen and a touchpad, non-contact input circuit using an optical sensor, and audio input circuit. Note that the input interface 102 is not limited to those equipped with physical operating components such as a mouse or keyboard. For example, an electrical signal processing circuit that receives electrical signals corresponding to input operations from an external input device provided separately from the device and outputs these electrical signals to a control circuit is also included as an example of the input interface 102.

[0014] The display 103 displays various information and images. Specifically, the display 103 converts the information and image data sent from the processing circuit 170 into electrical signals for display and outputs them. For example, the display 103 can be implemented as an LCD monitor, a CRT (Cathode Ray Tube) monitor, a touch panel, etc. The output device of the ultrasound diagnostic apparatus 100 is not limited to the display 103; for example, it may also be equipped with a speaker. For example, the speaker outputs a predetermined sound, such as a beep, to notify the operator of the processing status of the main unit 104 of the apparatus.

[0015] The main unit 104 is a device that generates an ultrasonic image based on the reflected wave signal received by the ultrasonic probe 101. For example, the main unit 104 generates a two-dimensional ultrasonic image based on two-dimensional reflected wave data received by the ultrasonic probe 101. The main unit 104 also generates a three-dimensional ultrasonic image based on three-dimensional reflected wave data received by the ultrasonic probe 101.

[0016] As shown in FIG. 1, the apparatus main body 104 includes a transceiver circuit 110, a buffer memory 120, a signal processing circuit 130, an image generation circuit 140, a memory circuit 150, a NW (network) interface 160, and a processing circuit 170. The transceiver circuit 110, the buffer memory 120, the signal processing circuit 130, the image generation circuit 140, the memory circuit 150, the NW interface 160, and the processing circuit 170 are communicably connected to each other.

[0017] An electrocardiograph for recording the potential of cardiomyocytes accompanying the heartbeat of the subject P to be ultrasonically scanned may be connected to the apparatus main body 104. The electrocardiograph generates an electrocardiogram waveform indicating the heartbeat of the subject P.

[0018] The transceiver circuit 110 includes a pulse generator, a transmission delay unit, a pulser, etc., and supplies a drive signal to the ultrasonic probe 101. The pulse generator repeatedly generates rate pulses for forming transmission ultrasonic waves at a predetermined rate frequency. Also, the transmission delay unit focuses the ultrasonic waves generated from the ultrasonic probe 101 into a beam shape, and gives the delay time for each piezoelectric vibrator necessary for determining the transmission directivity to each rate pulse generated by the pulse generator. Also, the pulser applies a drive signal (drive pulse) to the ultrasonic probe 101 at a timing based on the rate pulse. That is, the transmission delay unit arbitrarily adjusts the transmission direction of the ultrasonic waves transmitted from the vibrator surface by changing the delay time given to each rate pulse.

[0019] Also, the transceiver circuit 110 includes a preamplifier, an A / D (Analog to Digital) converter, a quadrature detection circuit, etc., and performs various processes on the reflected wave signal received by the ultrasonic probe 101 to generate reflected wave data. Then, the transceiver circuit 110 stores the generated reflected wave data in the buffer memory 120.

[0020] The preamplifier amplifies the reflected wave signal for each channel and performs gain adjustment (gain correction). The A / D converter converts the gain-corrected reflected wave signal into a digital signal by A / D conversion. The quadrature detection circuit converts the A / D-converted reflected wave signal into a baseband in-phase signal (I signal, I) and a quadrature-phase signal (Q signal, Q).

[0021] The quadrature detection circuit outputs the I signal and Q signal as reflected wave data. Hereafter, the I signal and Q signal will be collectively referred to as the IQ signal. Also, since the IQ signal is A / D converted digital data, it will also be called the IQ data.

[0022] The buffer memory 120 is implemented using semiconductor memory elements such as RAM (Random Access Memory) or flash memory. The buffer memory 120 stores the reflected wave data output from the transmit / receive circuit 110.

[0023] The signal processing circuit 130 performs logarithmic amplification, envelope detection, and other processes on the reflected wave data acquired from the buffer memory 120 to generate data (B-mode data) in which signal intensity is expressed as brightness. The signal processing circuit 130 also performs frequency analysis on velocity information from the reflected wave data acquired from the buffer memory 120, extracts blood flow, tissue, and contrast agent echo components due to the Doppler effect, and generates data (Doppler data) in which moving object information such as velocity, dispersion, and power is extracted for multiple points. Here, moving objects include, for example, blood flow, tissue of organs that move periodically such as the heart wall, and contrast agents.

[0024] Furthermore, the signal processing circuit 130 is capable of processing both two-dimensional and three-dimensional reflected wave data. That is, the signal processing circuit 130 generates two-dimensional B-mode data from two-dimensional reflected wave data and three-dimensional B-mode data from three-dimensional reflected wave data. In addition, the signal processing circuit 130 generates two-dimensional Doppler data from two-dimensional reflected wave data and three-dimensional Doppler data from three-dimensional reflected wave data.

[0025] The image generation circuit 140 generates an ultrasound image from the data generated by the signal processing circuit 130. For example, the image generation circuit 140 generates a two-dimensional B-mode image from the two-dimensional B-mode data generated by the signal processing circuit 130, in which the intensity of the reflected wave is represented by brightness.

[0026] Furthermore, the image generation circuit 140 generates Doppler image data representing moving object information from the Doppler data generated by the signal processing circuit 130. The Doppler image data is either velocity image data, distributed image data, power image data, or a combination thereof.

[0027] Furthermore, for example, the image generation circuit 140 can generate an M-mode image from time-series data of B-mode data on one scan line generated by the signal processing circuit 130. The image generation circuit 140 can also generate Doppler waveforms plotting blood flow and tissue velocity information over time from the Doppler data generated by the signal processing circuit 130.

[0028] Here, the image generation circuit 140 generally converts the scan line signal sequence of the ultrasonic scan into a scan line signal sequence of a video format, such as that used in televisions (scan conversion), and generates an ultrasonic image for display. Specifically, the image generation circuit 140 generates an ultrasonic image for display by performing coordinate transformations according to the ultrasonic scanning pattern of the ultrasonic probe 101. In addition to scan conversion, the image generation circuit 140 also performs various image processing tasks, such as image processing that regenerates an average brightness image using multiple image frames after scan conversion (smoothing process), and image processing that uses a differential filter within the image (edge ​​enhancement process). Furthermore, the image generation circuit 140 synthesizes various parameter text information, scales, body marks, etc., with the ultrasonic image data.

[0029] In other words, B-mode data and Doppler data are data before scan conversion processing, while the data generated by the image generation circuit 140 is image data for display after scan conversion processing. Hereinafter, the data before scan conversion processing (B-mode data and Doppler data) will also be referred to as "RAW data".

[0030] The image generation circuit 140 generates two-dimensional ultrasound images, namely two-dimensional B-mode images and two-dimensional Doppler images, from two-dimensional B-mode data and two-dimensional Doppler data, which are RAW data. The image generation circuit 140 can also generate superimposed images, for example, by superimposing a color Doppler image on a two-dimensional B-mode image.

[0031] The memory circuit 150 stores various types of data. For example, the memory circuit 150 stores control programs for ultrasound transmission and reception, image processing and display processing, diagnostic information (e.g., patient ID, doctor's findings, etc.), diagnostic protocols, and various body marks. For example, the memory circuit 150 can be implemented using semiconductor memory elements such as RAM (Random Access Memory) and flash memory, or a hard disk drive (HDD), optical disc, etc.

[0032] Furthermore, the data stored in the memory circuit 150 can be transferred to an external device via the NW interface 160. The external device could be, for example, a personal computer (PC) or tablet used by a physician performing diagnostic imaging, an image storage device for storing images, or a printer.

[0033] The NW interface 160 controls communication between the main unit 104 and external devices. Specifically, the NW interface 160 receives various types of information from external devices and outputs the received information to the processing circuit 170. For example, the NW interface 160 can be implemented using a network card, network adapter, NIC (Network Interface Controller), etc.

[0034] The processing circuit 170 controls the entire processing of the ultrasound diagnostic device 100. Specifically, the processing circuit 170 controls the processing of the transmitting / receiving circuit 110, the signal processing circuit 130, and the image generation circuit 140 based on various setting requests input from the operator via the input interface 102, and various control programs and data read from the memory circuit 150. The processing circuit 170 also controls the display of the ultrasound image.

[0035] Furthermore, the processing circuit 170 executes the irradiation control function 171, the measurement result acquisition function 172, the motion estimation function 173, the function application function 174, the notification function 175, the error correction function 176, the clutter removal function 177, and the display control function 178. Here, for example, each of the processing functions that are components of the processing circuit 170, namely the irradiation control function 171, the measurement result acquisition function 172, the motion estimation function 173, the function application function 174, the notification function 175, the error correction function 176, the clutter removal function 177, and the display control function 178, are stored in the memory circuit 150 in the form of programs that can be executed by a computer. The processing circuit 170 is a processor. For example, the processing circuit 170 reads the program from the memory circuit 150 and executes it to realize the function corresponding to each program. In other words, the processing circuit 170 in the state in which each program has been read has the functions shown in the processing circuit 170 of Figure 1. In Figure 1, the processing functions performed by the irradiation control function 171, measurement result acquisition function 172, motion estimation function 173, function application function 174, notification function 175, error correction function 176, clutter removal function 177, and display control function 178 are described as being realized by a single processor. However, it is also acceptable to configure a processing circuit 170 by combining multiple independent processors, with each processor executing a program to realize the functions. Furthermore, in Figure 1, a single memory circuit 150 is described as storing programs corresponding to each processing function. However, it is also acceptable to configure the processing circuit 170 by distributing multiple memory circuits and reading the corresponding programs from individual memory circuits.

[0036] In the above explanation, the term "processor" refers to circuits such as a CPU (Central Processing Unit), a GPU (Graphical Processing Unit), 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), and a Field Programmable Gate Array (FPGA)). The processor functions by reading and executing a program stored in the memory circuit 150. Alternatively, instead of storing the program in the memory circuit 150, the processor may be configured to directly incorporate the program into its circuitry. In this case, the processor functions by reading and executing the program incorporated into the circuitry.

[0037] The ultrasound diagnostic device 100 performs Shear Wave Elastography (SWE) to measure the stiffness distribution of the organs of the subject P. The ultrasound diagnostic device 100 performs SWE on organs that move periodically, such as the heart. Furthermore, the organ is not limited to the heart; any organ that moves periodically is acceptable. For example, the organ may be a pulsating circulatory organ, a pulsating blood vessel, or any other organ.

[0038] In SWE (Screen-Wounded Emission), the ultrasound diagnostic device 100 applies pressure to the target organ by irradiating it with pulsed ultrasound waves. The ultrasound diagnostic device 100 also measures the transverse waves that propagate through the organ, which are generated by the pressure. Here, the amount of movement, or displacement, of each point in the organ when pressurized differs between soft and hard parts. Therefore, the ultrasound diagnostic device 100 estimates the stiffness of each part of the organ by measuring the transverse waves. The ultrasound diagnostic device 100 then visualizes and displays the estimated stiffness results as an image. This allows medical professionals to detect lesions.

[0039] However, organs that move periodically, such as the heart, undergo displacement themselves. In other words, the displacement obtained from periodically moving organs includes both the displacement of the organ itself and the displacement of transverse waves caused by pressurization. Therefore, the ultrasound diagnostic device 100 removes clutter components, such as the displacement of the organ itself, from the displacement obtained from the organ being measured. As a result, the ultrasound diagnostic device 100 obtains the displacement caused by transverse waves propagating through the pressurized organ.

[0040] Here, Figure 2 is a graph showing an example of measurement results from the ultrasound diagnostic device 100. In the graph shown in Figure 2, the vertical axis represents the displacement, which is the amount of movement of the organs of subject P, and the horizontal axis represents the number of ultrasound irradiations. In other words, the graph shown in Figure 2 plots the Doppler data for ultrasound irradiated onto the organs of subject P.

[0041] The ultrasound diagnostic device 100 irradiates pulsed ultrasound during the reference period, push period, and tracking period in SWE. The reference period is the period during which the periodic motion of the organ to be measured is measured. The ultrasound diagnostic device 100 irradiates the reference pulse during the reference period and receives the reflected wave of the reference pulse. In this way, the ultrasound diagnostic device 100 acquires the displacement due to the periodic motion of the organ. The reference pulse is a pulsed ultrasound irradiated during the reference period.

[0042] The push period is the period during which the organ to be measured is pressurized. The ultrasound diagnostic device 100 pressurizes the organ by irradiating it with a push pulse during the push period. The push pulse is a pulsed ultrasound irradiated during the push period that pushes the organ to be measured. Note that the ultrasound diagnostic device 100 does not acquire reflected waves during the push period.

[0043] The tracking period is the period during which the displacement of transverse waves propagating through an organ is measured due to the pressurization of the organ. The ultrasound diagnostic device 100 irradiates a tracking pulse during the tracking period and receives the reflected wave of the reference pulse. In this way, the ultrasound diagnostic device 100 acquires the displacement of transverse waves propagating through the organ.

[0044] During the push period when the push pulse shown in Figure 2 is irradiated, the ultrasound diagnostic device 100 does not receive reflected waves. Therefore, continuity is lost between the reference period and the tracking period, and errors occur. Furthermore, as shown in Figure 2, the organ being measured is displaced itself. Therefore, the Doppler data contains components that interfere with the measurement of transverse waves propagating through the organ.

[0045] Therefore, the ultrasound diagnostic device 100 repeatedly irradiates the periodically moving organ with a reference pulse for at least one cycle during the reference period. The ultrasound diagnostic device 100 generates Doppler data from the reflected wave data of the reference pulses repeatedly irradiated during the reference period. The ultrasound diagnostic device 100 then generates first displacement information from the Doppler data, which records the temporal displacement of the periodically moving organ. The ultrasound diagnostic device 100 also calculates a function that represents the temporal displacement of the periodically moving organ based on the first displacement information. The ultrasound diagnostic device 100 then extracts the displacement of the transverse wave propagating through the organ by interpolating the parts where continuity has been lost due to the push pulse and removing the displacement of the organ itself, based on the function.

[0046] Specifically, the ultrasound diagnostic device 100 is realized through the following functions.

[0047] The irradiation control function 171 controls the ultrasound probe 101 to irradiate pulsed ultrasound during the reference period, push period, and tracking period. More specifically, the irradiation control function 171 causes the ultrasound probe 101 to repeatedly irradiate the ultrasound probe 101 with reference pulses, which are pulsed ultrasound, at predetermined intervals during the reference period. During the reference period, the irradiation control function 171 repeatedly irradiates periodically moving organs with reference pulses for at least one cycle. That is, the irradiation control function 171 irradiates reference pulses for the duration of at least one heartbeat in organs such as the heart. Furthermore, the robustness of the irradiation control function 171 can be improved as the number of heartbeats during the irradiation of reference pulses increases.

[0048] Furthermore, the irradiation control function 171 repeatedly irradiates the ultrasonic probe 101 with push pulses, which are pulsed ultrasonic waves, at predetermined intervals during the push period.

[0049] Furthermore, the irradiation control function 171 repeatedly irradiates the ultrasound probe 101 with tracking pulses, which are pulsed ultrasound waves, at predetermined intervals during the tracking period. Also, when repeatedly pressurizing an organ and measuring the transverse waves caused by the pressurization, the irradiation control function 171 repeats, for example, the reference period, the push period, and the tracking period in that order. The irradiation control function 171 then repeatedly irradiates with pulsed ultrasound during each period.

[0050] The irradiation control function 171 may repeat the push period and tracking period after the reference period has elapsed. Figure 3 is a diagram showing an example of the sequence in which ultrasound is irradiated by the ultrasound diagnostic device 100. As shown in Figure 3, the irradiation control function 171 repeatedly irradiates a reference pulse during the reference period. After that, the irradiation control function 171 may alternately irradiate with repeated push pulses during the push period and with repeated tracking pulses during the tracking period. That is, the ultrasound probe 101 repeatedly irradiates with a reference pulse, which is a pulsed ultrasound, to acquire first displacement information, and then alternately irradiates with repeated push pulses, which are pulsed ultrasounds that pressurize the organ, and with repeated tracking pulses, which are pulsed ultrasounds that acquire second displacement information. In this case, since the irradiation control function 171 repeats the push period and tracking period after the reference period has elapsed, the execution time can be reduced.

[0051] The measurement result acquisition function 172 collects the measurement results. The reflected wave data of each pulsed ultrasound irradiated by the irradiation control function 171 is stored in the buffer memory 120. The signal processing circuit 130 then generates Doppler data from the reflected wave data stored in the buffer memory 120. The measurement result acquisition function 172 collects the Doppler data of each reference pulse repeatedly irradiated during the reference period as first displacement information, which records the temporal displacement of a periodically moving organ.

[0052] Furthermore, the measurement result acquisition function 172 collects the Doppler data of each tracking pulse repeatedly irradiated during the tracking period as second displacement information, which records the temporal displacement of the organ after it has been pressurized.

[0053] The motion estimation function 173 estimates the motion of a periodically moving organ. Specifically, the motion estimation function 173 calculates a function relating to the clutter component from the organ based on first displacement information relating to the temporal displacement of the periodically moving organ. The clutter component is an unwanted component from the organ, such as the temporal displacement due to the movement of the organ itself. The motion estimation function 173 is an example of the first calculation unit. The first displacement information is an example of the first ultrasound information.

[0054] Here, Figure 4 shows an example of a method for calculating a function based on the first displacement information. As shown in Figure 4, the motion estimation function 173 calculates a function relating to the clutter component from an organ based on the first displacement information, which includes at least one period of the organ's temporal displacement. In other words, the motion estimation function 173 calculates a function that represents the temporal displacement of the organ. For example, the motion estimation function 173 calculates a function that represents the temporal displacement of the organ by finding a kernel function using a Gaussian process. However, the motion estimation function 173 is not limited to this method; it may also calculate the function by polynomial fitting to infer the function's parameters, or by the least squares method, etc.

[0055] The function application function 174 synchronizes the clutter component from the organ, represented by the function calculated by the motion estimation function 173, with the temporal displacement of the organ indicated by the second displacement information. The function application function 174 is an example of a synchronization unit. In other words, the function application function 174 extracts the range to be compared from the function calculated by the motion estimation function 173.

[0056] Figure 5 is an explanatory diagram illustrating an example of synchronization between the temporal displacement of an organ represented by a function and the displacement shown by the reflected wave data of the tracking pulse. Here, the ultrasound diagnostic device 100 compares the temporal displacement of the organ represented by a function with the displacement shown by the reflected wave data of the tracking pulse. For organs that move periodically, the ultrasound diagnostic device 100 cannot obtain a significant result by comparing the displacement at 1 / 4 of a cycle with the displacement at 2 / 4 of a cycle. Therefore, as shown in Figure 5, the function application function 174 synchronizes the temporal displacement of the organ represented by the function with the displacement shown by the reflected wave data of each tracking pulse in order to match the displacements to be compared.

[0057] For example, the function application function 174 synchronizes the clutter component from the organ represented by the function with the temporal displacement of the organ indicated by the second displacement information, based on the electrocardiogram waveform of the organ. Specifically, when the organ being measured is the heart, the function application function 174 identifies the period during which the reflected wave data of the tracking pulse was received, based on the electrocardiogram waveform. That is, the function application function 174 identifies which period of the electrocardiogram waveform corresponds to the period during which the reflected wave data of the tracking pulse was received. Then, the function application function 174 extracts the period corresponding to the identified period from the temporal displacement of the organ represented by the function. In this way, the function application function 174 synchronizes the clutter component from the organ represented by the function with the displacement indicated by the reflected wave data of each tracking pulse.

[0058] Alternatively, the function application function 174 synchronizes the time-dependent displacement of the organ represented by the function with the time-dependent displacement of the organ indicated by the second displacement information, based on a mutual function that calculates the similarity between the clutter component from the organ represented by the function and the time-dependent displacement of the organ indicated by the second displacement information. The mutual function calculates the similarity between the waveform representing the time-dependent displacement of the organ represented by the function and the waveform representing the time-dependent displacement of the organ indicated by the second displacement information, while changing the waveform interval. Then, the function application function 174 extracts the interval from the time-dependent displacement waveform of the organ represented by the function that has the highest similarity to the displacement waveform indicated by the reflected wave data of each tracking pulse. In this way, the function application function 174 synchronizes the clutter component from the organ represented by the function with the displacement indicated by the reflected wave data of each tracking pulse.

[0059] Here, while the push pulse is being irradiated, the ultrasound diagnostic device 100 does not receive the reflected waves of the push pulse. Therefore, the function application function 174 extracts the range from the function calculated by the motion estimation function 173 that corresponds to the period during which the push pulse is being irradiated, in order to estimate the displacement during the period during which the push pulse is being irradiated. For example, when the function application function 174 synchronizes the clutter component from the organ represented by the function with the displacement shown by the reflected wave data of the tracking pulse, it synchronizes from the period during which the push pulse is being irradiated. In this way, the function application function 174 extracts the range that corresponds to the period during which the push pulse is being irradiated. Alternatively, the function application function 174 extracts the range that corresponds to the period during which the push pulse is being irradiated by identifying the period during which the push pulse is being irradiated based on the electrocardiogram waveform.

[0060] The notification function 175 notifies when the similarity score, which indicates the degree of similarity between the clutter component from the organ represented by the function and the temporal displacement of the organ indicated by the second displacement information, is below a threshold. The notification function 175 is an example of a notification unit. Here, if the similarity score is low, the function may not be able to represent the periodic motion of the organ. Therefore, the function is likely to have failed to remove clutter components that should have been removed, or to have removed components that should have been left in. Thus, the notification function 175 notifies that the similarity score is low, that is, that the reliability of the measurement results of the transverse waves generated by pressurizing the organ is low. The notification function 175 may notify by any method. For example, the notification function 175 may notify by displaying on the display 103, by lighting up an LED (Light Emitting Diode), by making an audible notification, or by transmitting information to another device.

[0061] The error correction function 176 corrects the error in the displacement of the organ during the period it is pressurized, which is included in the second displacement information, based on a function. The error correction function 176 is an example of a correction unit. In other words, the error correction function 176 corrects the discontinuity caused by the push pulse. Here, while the push pulse is being irradiated, the ultrasound diagnostic device 100 does not receive the reflected waves of the push pulse. Immediately after the irradiation of the push pulse ends and the tracking period begins, the ultrasound diagnostic device 100 receives the reflected waves of the push pulse. Therefore, the error correction function 176 calculates the displacement of the organ during the period in which the push pulse was transmitted, based on the function corresponding to the period in which the push pulse was irradiated, which was extracted by the function application function 174. Then, the error correction function 176 corrects the second displacement information according to the calculation result.

[0062] The clutter removal function 177 calculates transverse waves propagating through the organ due to pressurization, based on a function relating to the clutter component from the organ and second displacement information relating to the temporal displacement of the organ after it has been pressurized. The clutter removal function 177 is an example of a second calculation unit. The second displacement information is an example of second ultrasound information. That is, the clutter removal function 177 calculates transverse waves propagating through the organ due to pressurization, based on a function synchronized by the function application function 174 and the second displacement information. Figure 6 is an explanatory diagram showing an example of a method for calculating transverse waves based on the second displacement information and a function. In the transverse waves shown in Figure 6, the solid line represents the transverse waves propagating through the organ due to pressurization, and the dotted line represents the displacement of the organ itself. As shown in Figure 6, the clutter removal function 177 calculates transverse waves by removing the clutter component from the second displacement information based on a function synchronized by the function application function 174. In this way, the clutter removal function 177 calculates transverse waves generated by pressurizing the organ with a push pulse.

[0063] The display control function 178 displays the transverse waves propagating through the organ, calculated by the clutter removal function 177, on the display 103. The display control function 178 may also display the stiffness of the organ estimated from the transverse waves. For example, the display control function 178 estimates the stiffness of each point in the organ based on the transverse waves propagating through it. Then, the display control function 178 displays an image in which a color corresponding to the stiffness is superimposed on the B-mode image of the organ, including each point. The display control function 178 may be displayed not only on the display 103, but also on a display device connected via the NW interface 160, or on other devices.

[0064] Next, the measurement process performed by the ultrasound diagnostic device 100 will be described. The measurement process involves measuring the transverse waves that propagate through the organs, which are generated by pressurization.

[0065] Figure 7 shows an example of the measurement process performed by the ultrasound diagnostic device 100 according to this embodiment.

[0066] The measurement result acquisition function 172 acquires first displacement information, which records the movement of a periodically moving organ for one or more cycles, and second displacement information, which records the displacement indicated by the reflected wave data of the repeatedly irradiated tracking pulse (step S1). Note that if the measurement result acquisition function 172 performs the measurement process while irradiating the subject P with ultrasound, the first and second displacement information may be acquired at other times.

[0067] The motion estimation function 173 calculates a function relating to the clutter component from an organ based on first displacement information relating to the temporal displacement of a periodically moving organ (step S2).

[0068] The function application function 174 synchronizes the clutter component from the organ represented by the function with the displacement indicated by the reflected wave data of the tracking pulse contained in the second displacement information (step S3).

[0069] The notification function 175 determines whether the similarity between the displacement waveform expressed by the function synchronized by the function application function 174 and the displacement waveform shown by the reflected wave data of the tracking pulse is above a threshold (step S4).

[0070] If the similarity is below the threshold (step S4; No), the notification function 175 notifies that the similarity between the displacement waveform represented by the function and the displacement waveform shown by the reflected wave data of the tracking pulse is low (step S5).

[0071] If the similarity is above a threshold (step S4; Yes), the notification function 175 does not send a notification. Furthermore, the timing of determining the similarity and the timing of sending notifications are not limited to step S5 and can be changed as needed. For example, the notification function 175 may calculate the similarity between the displacement waveform represented by the function and the displacement waveform shown by the reflected wave data of the tracking pulse after the function has been calculated but before synchronization, and send a notification according to the calculated similarity. Alternatively, the notification function 175 may calculate the similarity at multiple timings and send a notification according to the calculated similarity.

[0072] The clutter removal function 177 calculates the transverse waves propagating through the organ due to pressurization, based on a function relating to the clutter component from the periodically moving organ and second displacement information recording the temporal displacement of the organ after it has been pressurized (step S6).

[0073] The display control function 178 displays the stiffness of each point of the organ estimated based on the calculated transverse waves (step S7).

[0074] As a result, the ultrasound diagnostic device 100 terminates the measurement process.

[0075] As described above, the ultrasound diagnostic device 100 according to this embodiment irradiates a periodically moving organ such as the heart with a reference pulse, irradiates a push pulse to pressurize the organ, and irradiates the organ with a tracking pulse after pressurization. Based on the Doppler data generated by the reflected wave of the reference pulse, the ultrasound diagnostic device 100 generates first displacement information relating to the temporal displacement of the periodically moving organ. Furthermore, based on the Doppler data generated by the reflected wave of the tracking pulse, the ultrasound diagnostic device 100 generates second displacement information relating to the temporal displacement of the organ after it has been pressurized. Furthermore, based on the first displacement information, the ultrasound diagnostic device 100 calculates a function relating to the clutter component from the organ. In addition, based on the calculated function and the second displacement information, the ultrasound diagnostic device 100 calculates the transverse wave propagating through the organ due to pressurization. In other words, the ultrasound diagnostic device 100 calculates the transverse wave propagating through the organ due to pressurization by removing the displacement of the organ itself using a function. Therefore, the ultrasound diagnostic device 100 can apply SWE to periodically moving organs as well.

[0076] (Variation 1) In this embodiment, the ultrasound diagnostic device 100 is described as implementing the irradiation control function 171, measurement result acquisition function 172, motion estimation function 173, function application function 174, notification function 175, error correction function 176, clutter removal function 177, and display control function 178 by executing a program stored in the memory circuit 150. However, the ultrasound diagnostic device 100 may implement all or part of the irradiation control function 171, measurement result acquisition function 172, motion estimation function 173, function application function 174, notification function 175, error correction function 176, clutter removal function 177, and display control function 178 using hardware such as semiconductor circuits.

[0077] (Modification 2) In this embodiment, the measurement result acquisition function 172, motion estimation function 173, function application function 174, notification function 175, error correction function 176, clutter removal function 177, and display control function 178 are described as being provided by the ultrasound diagnostic device 100. However, these functions may also be provided by an analysis device, which is a computer device such as a server or workstation. For example, the ultrasound diagnostic device 100 transmits reflected wave data stored in the buffer memory 120 to the analysis device via an interface such as the NW interface 160. That is, the ultrasound diagnostic device 100 transmits first displacement information and second displacement information to the analysis device. The analysis device then performs various processes on the first displacement information and second displacement information.

[0078] According to at least one embodiment described above, SWE can be applied to organs that move periodically.

[0079] While several embodiments have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be implemented in a variety of other forms, and various omissions, substitutions, modifications, and combinations of embodiments are possible without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of symbols]

[0080] 100 Ultrasound diagnostic equipment 101 Ultrasound probe 102 Input Interfaces 103 displays 104 Main unit of the device 110 Transmit / Receive Circuit 120 buffer memory 130 Signal Processing Circuits 140 Image generation circuit 150 Memory circuit 160 NW (network) interfaces 170 Processing Circuits 171 Irradiation control function 172 Measurement result acquisition function 173. Motion Estimation Function 174 Function Application Function 175 Notification function 176 Error Correction Function 177 Clutter Removal Function 178 Display Control Function P Subject

Claims

1. A first calculation unit that calculates a function relating to the clutter component indicating the displacement over time due to the movement of the heart, based on first ultrasonic information relating to the displacement over time due to the movement of the heart before it is pressurized by irradiating pulsed ultrasonic waves, A second calculation unit calculates transverse waves propagating through the heart due to the pressurization, based on the aforementioned function and second ultrasonic information relating to the temporal displacement due to the movement of the heart after the heart has been pressurized. An ultrasound diagnostic device equipped with the following features.

2. The second calculation unit calculates the transverse wave by removing the clutter component from the second ultrasonic information based on the function. The ultrasound diagnostic apparatus according to claim 1.

3. The system further comprises a synchronization unit that synchronizes the clutter component, which represents the temporal displacement due to the movement of the heart as expressed by the function, with the temporal displacement due to the movement of the heart as indicated by the second ultrasonic information, The second calculation unit calculates the transverse wave based on the temporal displacement due to cardiac motion indicated by the clutter component and the temporal displacement due to cardiac motion indicated by the second ultrasonic information, which are synchronized by the synchronization unit. The ultrasound diagnostic apparatus according to claim 1.

4. The synchronization unit synchronizes the clutter component, which represents the temporal displacement due to the movement of the heart expressed by the function, with the temporal displacement due to the movement of the heart, as indicated by the second ultrasonic information, based on the electrocardiogram waveform of the heart. The ultrasound diagnostic apparatus according to claim 3.

5. The synchronization unit synchronizes the displacement due to the heart's motion, as expressed by the function, with the displacement due to the heart's motion, as indicated by the second ultrasonic information, based on a mutual function that calculates the similarity between the clutter component, which represents the displacement due to the heart's motion over time as expressed by the function, and the displacement due to the heart's motion over time as indicated by the second ultrasonic information. The ultrasound diagnostic apparatus according to claim 3.

6. The system further includes a notification unit that notifies that the reliability of the measurement result of the transverse wave generated by pressurizing the heart is low when the similarity, which indicates the degree to which the clutter component representing the temporal displacement due to the movement of the heart expressed by the function is similar to the temporal displacement due to the movement of the heart indicated by the second ultrasonic information, is below a threshold. The ultrasound diagnostic apparatus according to claim 1.

7. The first calculation unit calculates the function relating to the clutter component that indicates the displacement over time due to the movement of the heart, based on the first ultrasonic information which includes at least one period of displacement over time due to the movement of the heart. The ultrasound diagnostic apparatus according to claim 1.

8. The system further includes a correction unit that corrects errors in the cardiac displacement included in the second ultrasonic information, in accordance with the calculation result of the cardiac displacement during the pressurized period, which is calculated based on the function described above. The ultrasound diagnostic apparatus according to claim 1.

9. The system further includes an ultrasonic probe that emits pulsed ultrasound and receives reflected waves. The ultrasound probe repeatedly irradiates pulsed ultrasound to acquire first ultrasound information, and then alternately performs repeated pulsed ultrasound irradiation to pressurize the heart and repeated pulsed ultrasound irradiation to acquire second ultrasound information. An ultrasound diagnostic apparatus according to any one of claims 1 to 8.

10. A first calculation unit that calculates a function relating to a clutter component indicating the displacement over time due to the movement of the heart, based on first ultrasonic information relating to the displacement over time due to the movement of the heart before it is pressurized by irradiating pulsed ultrasonic waves, A second calculation unit calculates transverse waves propagating through the heart due to the pressurization, based on the aforementioned function and second ultrasonic information relating to the temporal displacement due to the movement of the heart after the heart has been pressurized. An analytical device equipped with the following features.

11. Computers, A first calculation unit calculates a function relating to the clutter component that indicates the temporal displacement due to the movement of the heart, based on first ultrasonic information relating to the temporal displacement due to the movement of the heart before it is pressurized by irradiating it with pulsed ultrasound, A second calculation unit calculates transverse waves propagating through the heart due to the pressurization, based on the aforementioned function and second ultrasonic information relating to the temporal displacement due to the movement of the heart after the heart has been pressurized. A program to make it work.

Images