阅读说明：本技术 超声波图像生成装置、程序存储介质以及超声波诊断装置 (Ultrasonic image generating device, program storage medium, and ultrasonic diagnostic device ) 是由 石黑俊 于 2021-03-03 设计创作，主要内容包括：提供超声波图像生成装置、程序存储介质及超声波诊断装置。目的在于在血流速度向量的解析对象的区域中合适地示出具有广度的区域中的血液的流量。在缓冲注入运算中,将在从第1解析定时到第2解析定时的期间执行如下动作的解析模型作为运算对象：从液体源对缓冲容器以固定流量注入液体,每当缓冲容器充满时,就将缓冲容器清空并继续从液体源对缓冲容器以固定流量注入液体。在缓冲注入运算中,每当缓冲容器充满的定时,就在流入口产生粒子,在直至到达第2解析定时时为止使该粒子沿着血流速度向量所表示的流入方向移动了时,求取在第2解析定时下出现的粒子的位置。在超声波诊断装置中,生成使粒子呈现在针对第2解析定时求取到的位置的超声波图像。(Provided are an ultrasonic image generating device, a program storage medium and an ultrasonic diagnostic device. The purpose is to appropriately show the flow rate of blood in a region having a wide range in a region to be analyzed for a blood flow velocity vector. In the buffer injection operation, an analysis model which executes the following operation in the period from the 1 st analysis timing to the 2 nd analysis timing is used as an operation object: the buffer container is filled with liquid from the liquid source at a fixed flow rate, and each time the buffer container is filled, the buffer container is emptied and the liquid filling of the buffer container from the liquid source at the fixed flow rate is continued. In the buffer injection calculation, particles are generated at the inflow port every time the buffer container is filled, and when the particles are moved in the inflow direction indicated by the blood flow velocity vector until the 2 nd analysis timing is reached, the positions of the particles appearing at the 2 nd analysis timing are obtained. In the ultrasonic diagnostic apparatus, an ultrasonic image is generated in which particles are present at the position obtained at the 2 nd analysis timing.)

1. An ultrasonic image generation device is characterized by comprising a processor for executing the following processing:

obtaining a blood flow velocity vector set at a flow entrance on an analysis target region;

obtaining an inflow blood flow volume flowing from the inflow port during a period from a 1 st analysis timing to a 2 nd analysis timing based on the blood flow velocity vector; and

generating an ultrasonic image at the 2 nd analysis timing by performing a buffer injection operation based on the inflow blood flow volume and the blood flow velocity vector,

the buffer injection operation is as follows: determining the number and positions of particles appearing in the ultrasound image based on the inflow blood flow volume, a predetermined buffer volume, and the blood flow velocity vector, and generating the ultrasound image in which particles are present at the positions of the particles,

the buffer capacity is a value for determining a distance between particles based on the inflow blood flow when a plurality of particles are present in the ultrasound image.

2. The ultrasonic image generation apparatus according to claim 1,

the inflow port is one of a plurality of divided openings obtained by dividing a blood flow opening set in the analysis target region.

3. The ultrasonic image generation apparatus according to claim 1 or 2,

the buffer injection operation is as follows:

an operation of injecting the liquid at a constant flow rate from a liquid source containing the liquid having the inflow blood flow rate into a buffer container having the buffer capacity, emptying the buffer container and continuing to inject the liquid at the constant flow rate each time the buffer container is filled,

when the above operation is performed virtually during the period from the 1 st analysis timing to the 2 nd analysis timing, particles are generated at the inflow port every time the buffer container is filled, and when the particles are moved in the direction indicated by the blood flow velocity vector until the 2 nd analysis timing is reached, the positions of the particles appearing at the 2 nd analysis timing are obtained.

4. The ultrasonic image generation apparatus according to claim 3,

the processor repeatedly performs the buffer injection operation,

in each of the buffer injection operations, the following actions are performed virtually: injecting the liquid into the buffer container after the 1 st analysis timing in a state where an initial amount of the liquid is contained in the buffer container at the 1 st analysis timing,

Each of the buffer injection operations is an operation in which the amount of the liquid remaining in the liquid source at the 2 nd analysis timing is set to an initial amount of the buffer injection operation to be executed next time.

5. An ultrasonic diagnostic apparatus is characterized by comprising:

the ultrasonic image generation apparatus according to claim 1; and

a blood flow velocity calculation device for obtaining the blood flow velocity vector by transmitting and receiving ultrasonic waves,

the processor obtains the blood flow velocity vector from the blood flow velocity calculation device.

6. The ultrasonic diagnostic apparatus according to claim 5,

the ultrasonic diagnostic apparatus includes:

a tomographic image generation device that generates a tomographic image by transmission and reception of ultrasonic waves; and

a display unit for displaying the ultrasonic image,

the ultrasonic image is an image in which the particles are depicted on the tomographic image.

7. A program storage medium storing an ultrasonic image generation program, the program storage medium characterized in that,

the ultrasonic image generation program causes a processor to execute:

obtaining a blood flow velocity vector set at a flow entrance on an analysis target region;

Obtaining an inflow blood flow volume flowing from the inflow port during a period from a 1 st analysis timing to a 2 nd analysis timing based on the blood flow velocity vector; and

generating an ultrasonic image at the 2 nd analysis timing by performing a buffer injection operation based on the inflow blood flow volume and the blood flow velocity vector,

the buffer injection operation is as follows: determining the positions of particles appearing in the ultrasonic image based on the inflow blood flow volume, a predetermined buffer volume, and the blood flow velocity vector, and generating the ultrasonic image in which the particles are present at the positions of the particles,

the buffer capacity is a value for determining a distance between particles based on the inflow blood flow when a plurality of particles are present in the ultrasound image.

Technical Field

The present invention relates to an ultrasonic image generating apparatus, a program storage medium, and an ultrasonic diagnostic apparatus, and more particularly to a technique for generating an image relating to blood flow.

Background

An ultrasonic diagnostic apparatus for measuring a blood flow velocity of a subject is widely used. In such an ultrasonic diagnostic apparatus, a VFM (Vector Flow Mapping) in which a blood Flow velocity Vector is superimposed and displayed on a tomographic image by an arrow or the like is executed to diagnose a circulatory organ such as a blood vessel or a heart. In an ultrasonic diagnostic apparatus that performs VFM, a blood flow velocity vector is measured using a doppler method.

Patent documents 1 and 2 below show techniques for characterizing a blood flow velocity vector obtained by VFM using particles drawn on an image. In this technique, an interpolation frame for interpolating between an image frame generated at a previous timing and an image frame generated at a next timing is generated. In each image represented by an image frame or an interpolation frame, a particle that moves on the image with the passage of time is drawn. Patent document 3 describes a basic technique for measuring a blood flow velocity.

Documents of the prior art

Patent document

Patent document 1: JP 2016-214438A

Patent document 2: JP 2016 laid-open No. 202621

Patent document 3: JP 2015-198777 publication

In the techniques described in patent documents 1 and 2, blood flow velocity vectors at respective points in the heart are expressed on an image. However, this technique has the following problems: the volume of blood flowing through a region that is not a point but has a breadth per a given time cannot be represented, i.e., the flow rate of blood in a region having a breadth cannot be represented.

Disclosure of Invention

An object of the present invention is to appropriately show the flow rate of blood in a region having a wide range in a region to be analyzed for a blood flow velocity vector.

The present invention is characterized by comprising a processor for executing: obtaining a blood flow velocity vector set at a flow entrance on an analysis target region; obtaining an inflow blood flow volume flowing from the inflow port during a period from a 1 st analysis timing to a 2 nd analysis timing based on the blood flow velocity vector; and generating an ultrasound image at the 2 nd analysis timing by performing a buffer injection operation based on the inflow blood flow volume and the blood flow velocity vector, the buffer injection operation being an operation of: the number and positions of particles appearing in the ultrasound image are determined based on the inflow blood flow volume, a predetermined buffer volume, and the blood flow velocity vector, and the ultrasound image is generated in which particles are caused to appear at the positions of the particles, the buffer volume being a value that determines the distance between particles based on the inflow blood flow volume when a plurality of particles are present in the ultrasound image.

Effects of the invention

According to the present invention, the flow rate of blood in a region having a breadth can be appropriately shown in the region to be analyzed of the blood flow velocity vector.

Drawings

Fig. 1 is a diagram showing a configuration of an ultrasonic diagnostic apparatus.

Fig. 2 is a diagram showing an image displayed on the display unit to set conditions in the VFM.

Fig. 3 is a conceptual diagram illustrating a process of virtually setting an inflow port to a blood flow opening.

Fig. 4 is a diagram showing an analysis model of the buffer injection operation.

Fig. 5 is a diagram schematically showing an ultrasonic image in which each particle is plotted on a tomographic image.

Fig. 6 is a diagram schematically showing an ultrasonic image in which each particle is plotted on a tomographic image.

Description of reference numerals:

10 ultrasonic probe

12 transceiver circuit

14 transmitting circuit

16 receiving circuit

18 arithmetic device

20 display part

22 control part

24 operating part

26 storage device

28 tomographic image generation unit

30 blood flow velocity calculating part

32 particle position calculating part

34 condition setting unit

38 display processing unit

40. 41 ultrasound wave beam

50 heart

52 left atrium

54 left ventricle

56 mitral valve

58 reference line

60 line of opening

61 blood flow opening

62 mitral annulus wall

64 flow inlet

68 buffer container

72 initial amount of liquid

74 residual amount of liquid

80. 80-1 to 80-3 particles

Detailed Description

Embodiments of the present invention will be described with reference to the drawings. The same items shown in the plural figures are denoted by the same reference numerals and the description is simplified.

Fig. 1 shows a configuration of an ultrasonic diagnostic apparatus according to an embodiment of the present invention. The ultrasonic diagnostic apparatus includes an ultrasonic probe 10, a transmission/reception circuit 12, an arithmetic device 18, a display unit 20, a control unit 22, an operation unit 24, and a storage device 26. The operation unit 24 includes a keyboard, a mouse, a knob, an operation lever, and the like, and outputs operation information based on an operation by the user to the control unit 22. The control unit 22 performs overall control of the ultrasonic diagnostic apparatus based on the operation information. The display section 20 may be a liquid crystal display, an organic EL display, or the like. The display unit 20 may constitute a touch panel together with the operation unit 24.

As the storage device 26 as a storage medium, a storage device such as a hard disk, a USB memory, and an SD card is used, for example. The storage device 26 may also be a storage on a communication line such as the internet.

The calculation device 18 includes a tomographic image generation unit 28, a blood flow velocity calculation unit 30, a particle position calculation unit 32, a condition setting unit 34, and a display processing unit 38. The computing device 18 may be a processor that executes a program stored in an external storage medium or a program storage medium such as the storage device 26 to internally configure these components (the tomographic image generation unit 28, the blood flow velocity calculation unit 30, the particle position calculation unit 32, the condition setting unit 34, and the display processing unit 38). Information used in the calculation, information to be temporarily stored in the course of the calculation, information obtained as a result of the calculation, and the like for each constituent element may be stored in the storage device 26.

The 1 component provided in the arithmetic device 18 may be configured by a plurality of processors that execute distributed processing. In addition, some or all of the plurality of components included in the arithmetic device 18 may be constituted by an external computer. The external computer may be directly connected to the arithmetic device 18 or may be connected to a communication line such as the internet. The 1 component provided in the arithmetic device 18 may be constituted by a plurality of external computers that execute distributed processing. Further, a part or all of the plurality of constituent elements included in the arithmetic device 18 may be constituted by an electronic circuit alone as hardware.

The ultrasonic diagnostic apparatus is configured to operate in a B mode in which a tomographic image of a subject is obtained. In the B mode, the transmission/reception circuit 12, the ultrasonic probe 10, the computing device 18, and the display unit 20 operate as described below under the control of the control unit 22.

The transmission/reception circuit 12 includes a transmission circuit 14 and a reception circuit 16. The ultrasonic probe 10 includes a plurality of vibration elements. The transmission circuit 14 outputs a transmission signal to each vibration element. Each of the transducers converts the transmission signal into ultrasonic waves and transmits the ultrasonic waves to the subject. The transmission circuit 14 adjusts delay times of transmission signals output to the respective vibration elements so that ultrasonic waves emitted from the respective vibration elements are mutually intensified in a specific direction, forms a transmission ultrasonic beam based on the ultrasonic waves in the specific direction, and scans the transmission ultrasonic beam over the object.

Each of the plurality of transducers receives ultrasonic waves reflected by the subject, converts the ultrasonic waves into an electric signal, and outputs the electric signal to the receiving circuit 16. The reception circuit 16 performs phase modulation and addition on the electric signals output from the respective vibration elements so that the electric signals based on the ultrasonic waves received from the transmission ultrasonic wave beam direction are mutually enhanced to generate reception signals, and outputs the reception signals to the arithmetic device 18. Thereby, a reception ultrasonic beam is formed in the ultrasonic probe 10, and a reception signal corresponding to the reception ultrasonic beam is output from the transmission/reception circuit 12 to the arithmetic device 18 as a reception signal for generating a tomographic image. In the following description, the term "ultrasound beam" is used as a general term for the transmission ultrasound beam and the reception ultrasound beam.

The tomographic image generation unit 28 configured inside the computing device 18 generates tomographic image frames based on the reception signals obtained for the respective ultrasonic beam directions corresponding to the scanning directions, and outputs the tomographic image frames to the display processing unit 38. The display processing unit 38 displays a tomographic image based on the tomographic image frame on the display unit 20. In addition, the tomographic image generation section 28 stores the tomographic image frames in the storage device 26.

In the B mode, the transmission/reception circuit 12, the ultrasonic probe 10, and the computing device 18 repeatedly perform scanning of the ultrasonic beam 40 on the object under the control of the control unit 22. The tomographic image generation unit 28 sequentially obtains tomographic image frames at a predetermined frame rate with the passage of time, and stores the tomographic image frames in the storage device 26.

The ultrasonic diagnostic apparatus is configured to operate in a doppler measurement mode for obtaining a blood flow velocity vector in addition to the B mode. In the doppler measurement mode, the transmission/reception circuit 12, the ultrasonic probe 10, and the computing device 18 operate as described below under the control of the control unit 22. The operation in the B mode and the operation in the doppler measurement mode can be performed in a time division manner by performing the ultrasonic transmission and reception in the operation in the B mode and the ultrasonic transmission and reception in the operation in the doppler measurement mode in a time division manner.

The control unit 22 controls the transmission/reception circuit 12 to scan the transmission ultrasonic beam formed in the ultrasonic probe 10 and to transmit the ultrasonic wave for the doppler measurement mode in each transmission ultrasonic beam direction. The analysis target region of the transmission ultrasonic beam for the scanning doppler measurement mode may be a region included in the region in which the ultrasonic beam 40 is scanned in the B mode. Each of the plurality of transducers receives ultrasonic waves reflected by the subject, converts the ultrasonic waves into an electric signal, and outputs the electric signal to the receiving circuit 16.

The reception circuit 16 performs phase adjustment and addition of electric signals output from the respective ultrasonic transducers of the ultrasonic probe 10 under the control of the control unit 22 to generate a reception signal for the doppler measurement mode, and outputs the reception signal to the computing device 18. As a result, a reception ultrasonic beam is formed in the ultrasonic probe 10, and a reception signal corresponding to the reception ultrasonic beam is output from the transmission/reception circuit 12 to the computing device 18 as a reception signal for the doppler measurement mode.

The blood flow velocity calculation unit 30 configured inside the calculation device 18 analyzes the doppler shift frequency of the received signal obtained for each ultrasonic beam direction corresponding to the scanning direction, and obtains an ultrasonic beam direction component of the blood flow velocity at each position on each ultrasonic beam 41 scanned in the analysis target region. The blood flow velocity calculation unit 30 obtains an orthogonal component orthogonal to the ultrasonic beam direction component for each position on each ultrasonic beam 41 based on the ultrasonic beam direction component of the blood flow velocity at each position on each ultrasonic beam 41, using the calculation described in patent document 3, for example. In patent document 3, the ultrasonic beam direction component and the orthogonal component are referred to as a doppler measurement component and a cross path direction component, respectively.

The operation described in patent document 3 is an operation of obtaining a quadrature component corresponding to an ultrasonic beam direction component based on a differential equation conforming to the law of conservation of mass. Here, the mass conservation law is not a law of only inflow or outflow of blood in a certain closed space, but a law of outflow of blood from the closed space in the same volume as the volume of the inflow blood.

By this processing, the blood flow velocity calculation unit 30 obtains a blood flow velocity vector including an ultrasonic beam direction component and a perpendicular component for each position in the analysis target region. The blood flow velocity calculation unit 30 may perform coordinate conversion processing on the blood flow velocity vector. The blood flow velocity calculation unit 30 may convert a blood flow velocity vector including an ultrasonic beam direction component and an orthogonal component into a blood flow velocity vector represented by an orthogonal coordinate system, for example. The blood flow velocity calculation unit 30 stores the blood flow velocity vectors obtained for the respective positions in the analysis target region in the form of a blood flow velocity data set shown below in the storage device 26.

In the doppler measurement mode, the transmission/reception circuit 12, the ultrasonic probe 10, and the computing device 18 repeatedly perform scanning of the ultrasonic beam 41 on the object under the control of the control unit 22. The blood flow velocity calculation unit 30 sequentially obtains a blood flow velocity data set representing a group of blood flow velocity vectors obtained for the analysis target region at a predetermined frame rate with the passage of time, and stores the blood flow velocity data set in the storage device 26.

As described above, the ultrasonic probe 10, the transmission/reception circuit 12, and the tomographic image generation unit 28 constitute a tomographic image generation device that generates a tomographic image by transmission/reception of ultrasonic waves. The ultrasonic probe 10, the transmission/reception circuit 12, and the blood flow velocity calculation unit 30 constitute a blood flow velocity calculation device that obtains a blood flow velocity vector by transmission/reception of ultrasonic waves.

The ultrasonic diagnostic apparatus operates as an ultrasonic image generating apparatus that generates an ultrasonic image. That is, the ultrasonic diagnostic apparatus performs VFM based on the tomographic image frames and the blood flow velocity data set stored in the storage device 26. VFM is processed as follows: data representing an ultrasonic image obtained by superimposing a graph representing the blood flow rate on the tomographic image is generated based on the tomographic image frame and the blood flow velocity data set, and the ultrasonic image is displayed on the display unit 20.

The flow rate of blood characterizes the volume of blood flowing through a given region per a given time. As will be described later, the flow rate of blood is characterized by the position and number of particles depicted on the tomographic image. The term "particle" in the present specification means a pattern that represents blood flow. The "particle" may be a circular, polygonal mark, or may be represented by a figure such as an arrow.

Fig. 2 shows an image displayed on the display unit 20 by the display processing unit 38 in order to set the condition in the VFM. In this figure, the left atrium 52, left ventricle 54, and mitral valve 56 of heart 50 are shown. The control unit 22 controls the condition setting unit 34 in accordance with the operation of the operation unit 24, and the condition setting unit 34 sets the reference line 58 in accordance with the control of the control unit 22. In fig. 2, a reference line 58 set at the position of the mitral valve 56d is shown in order to distinguish the boundary between the left atrium 52 and the left ventricle 54. The reference line 58 is a straight line having a length from the mitral annulus wall on the right side to the mitral annulus wall on the left side.

The condition setting unit 34 sets a straight line obtained by moving the reference line 58 in parallel to the left ventricle 54 side by a predetermined distance as the opening line 60. The condition setting unit 34 sets a blood flow opening 61 on the opening line 60. In the VFM, an operation based on the flow rate at the blood flow opening 61 is performed.

Thus, a reference line 58 is set at the position of the mitral valve 56 in order to distinguish the boundary between the left atrium 52 and the left ventricle 54. An opening line 60 is set on the left ventricle 54 side at a predetermined distance in parallel with the reference line 58, and a blood flow opening 61 is set on the opening line 60. This determines the flow rate of blood at a position where the flow rate of blood in the left ventricle 54 is relatively large.

Fig. 3 conceptually illustrates a process of setting the inflow port 64 to the blood flow opening 61. The condition setting unit 34 sets an interval on the opening line 60 sandwiched by the mitral valve annulus wall 62 as the blood flow opening 61. The condition setting unit 34 further divides the blood flow opening 61 and the like, and sets each section obtained by the division as the inflow port 64. Fig. 3 shows an example in which 10 divided openings obtained by dividing the blood flow opening 61 into 10 sections are set as the inflow ports 64. The condition setting unit 34 generates inflow port information indicating the direction in which the opening line 60 extends and the range occupied by each of the 10 inflow ports 64.

The particle position calculation unit 32 performs a particle position calculation based on the inflow port information obtained by the condition setting unit 34 and each blood flow velocity data set stored in the storage device 26 in advance, and obtains the position and the number of particles drawn on the tomographic image.

The particle position calculation is described below. The particle position calculation is an operation of calculating the position and number of particles corresponding to a succeeding blood flow velocity data set based on a preceding blood flow velocity data set and a succeeding blood flow velocity data set adjacent in time series (on a time axis) among blood flow velocity data sets sequentially calculated with the passage of time. In addition, in the particle position calculation, the same process is performed for each of the plurality of inlets. The processing performed for 1 flow inlet is explained here.

Further, the particle position calculation unit 32 repeatedly performs the particle position calculation with respect to the blood flow velocity data set stored in the storage device 26. That is, when the 1 st blood flow velocity data set, the 2 nd blood flow velocity data set, · · nth blood flow velocity data set generated in time series are stored in the storage device 26, particle position calculation for the 1 st and 2 nd blood flow velocity data sets, particle position calculation for the 2 nd and 3 rd blood flow velocity data sets, particle position calculation for the 3 rd and 4 th blood flow velocity data sets, and · · nth-1 and nth blood flow data sets are executed.

The particle position calculating unit 32 obtains the inflow blood flow rate at the inlet. The inflow blood flow volume is obtained by multiplying a value obtained by multiplying the velocity [ m/s ] of blood flow by the width [ m ] of the inflow port by the frame time interval [ s ] by the volume (area, because it is considered as a two-dimensional plane) of blood flowing into the inflow port from the generation of the previous blood flow velocity data set to the generation of the subsequent blood flow velocity data set. The frame time interval is the inverse of the frame rate at which the tomographic image frames and the blood flow velocity dataset are generated. The velocity of the blood flow is a component of the blood flow velocity vector at the inflow port in a direction perpendicular to the inflow port. The blood flow velocity vector is a blood flow velocity vector based on a subsequent blood flow velocity data set. In the following description, the timing at which the preceding blood flow velocity data set is generated is referred to as the 1 st analysis timing, and the timing at which the succeeding blood flow velocity data set is generated is referred to as the 2 nd analysis timing.

The particle position calculation unit 32 performs a buffer injection calculation on the inflow blood flow rate as follows. An analytical model of the buffer injection operation is conceptually shown in fig. 4. In the buffer injection calculation, a liquid source 70 containing a liquid flowing in the blood flow volume and a buffer container 68 having a predetermined buffer capacity are used in a virtual manner. Then, an analysis model that performs the following operations during a period from the 1 st analysis timing to the 2 nd analysis timing is set as an object of calculation: the buffer vessel 68 is filled with liquid from the liquid source 70 at a fixed flow rate, the buffer vessel 68 is emptied each time the buffer vessel 68 is filled, and the filling of the buffer vessel 68 with liquid from the liquid source 70 at a fixed flow rate is continued.

Fig. 4 (a1) to (a4) show the buffer container 68 and the liquid stored in the buffer container 68. The positions of the particles drawn on the tomographic image are shown in (b1) to (b4) of fig. 4.

At the 1 st analysis timing, that is, the timing at which the 1-time buffer injection operation is started, as shown in fig. 4 (a1), the initial amount of the liquid 72 is stored in the buffer container 68. The initial amount is the same value as the amount (residual amount) of the liquid remaining in the buffer container 68 in the previously performed buffer injection operation. The liquid source 70 contains liquid flowing into the blood flow. As shown in fig. 4 (b1), no particles are arranged on the tomographic image.

In the analytical model, the liquid contained in the liquid source 70 is injected into the buffer container 68 at a constant flow rate. As shown in fig. 4 (a2), when the buffer container 68 is filled with liquid, particles are arranged at the center of the inflow 64 on the tomographic image. Fig. 4 (b2) shows the particle 80-1 arranged in the center of the inflow 64 on the tomographic image. The particle 80-1 moves with time in a direction represented by a blood flow velocity vector based on the subsequent blood flow velocity data set.

Fig. 4 (a3) shows a state in which after the buffer container 68 is temporarily emptied, the liquid contained in the liquid source 70 is injected into the buffer container 68 at a constant flow rate and the buffer container 68 is refilled with the liquid. When the buffer container 68 is filled with the liquid again, the particles are arranged at the center of the inflow port 64 on the tomographic image. Fig. 4 (b3) shows a particle 80-2 arranged at the center of the inflow port 64 on the tomographic image. As shown in fig. 4 (b3), while the state of the analytical model transitions from the state of fig. 4 (a2) to the state of fig. 4 (a3), the particle 80-1 moves in the direction indicated by the blood flow velocity vector based on the subsequent blood flow velocity data set.

In the analytical model, the operation of injecting the liquid from the liquid source 70 into the buffer tank 68 at a constant flow rate, emptying the buffer tank 68 and continuing to inject the liquid from the liquid source 70 at a constant flow rate each time the buffer tank 68 is filled, is repeated until the liquid contained in the liquid source 70 is empty. At each timing when the buffer container 68 is filled, particles are arranged in the inflow 64, and the particles move in a direction indicated by a blood flow velocity vector based on the subsequent blood flow velocity data set.

Fig. 4 (a4) shows the liquid (residual liquid 74) stored in the buffer container 68 at the 2 nd analysis timing after the liquid stored in the liquid source 70 becomes empty, that is, at the timing when the 1 buffer injection operation is completed. The remaining amount of the liquid is used as an initial value in the buffer injection operation to be performed next time. In FIG. 4, (b4) shows particles 80-1 to 80-3 moving from the center of the inflow 64 on the tomographic image.

As described above, in the buffer injection operation, particles are generated in the inflow 64 every time the buffer container 68 is filled, and when the particles are moved in the inflow direction indicated by the blood flow velocity vector until the 2 nd analysis timing is reached, the positions of the particles appearing at the 2 nd analysis timing are obtained. The buffer capacity is a value for determining the distance between particles based on the inflow blood flow when a plurality of particles are present on the tomographic image.

In the buffer injection operation, the following actions are performed virtually: in a state where the initial amount of liquid is contained in the buffer container 68 at the 1 st analysis timing, the liquid is injected into the buffer container 68 after the 1 st analysis timing. In the buffer injection operation, the amount of the liquid remaining in the liquid source 70 at the 2 nd analysis timing becomes the initial amount of the buffer injection operation in the particle position operation to be performed next time.

After performing the particle position calculation for the preceding blood flow velocity data set and the succeeding blood flow velocity data set, the display processing unit 38 causes the display unit 20 to display an ultrasonic image in which each particle is rendered on a tomographic image, using the tomographic image frame corresponding to the succeeding blood flow velocity data set. That is, the display processing unit 38 generates ultrasonic image data in which each particle is rendered on a tomographic image represented by a tomographic image frame, and displays an ultrasonic image based on the ultrasonic image data on the display unit 20.

When the 1 st blood flow velocity dataset and the 1 st tomographic image frame, the 2 nd blood flow velocity dataset and the 2 nd tomographic image frame, and the · nth blood flow velocity dataset and the nth tomographic image frame generated in time series order are stored in the storage device 26, the display processing unit 38 sequentially generates ultrasonic image data as follows, and displays an ultrasonic image based on the ultrasonic image data on the display unit 20. Wherein N is an integer of 1 or more.

That is, the display processing unit 38 first generates ultrasonic image data based on the 1 st blood flow velocity data set and the 1 st tomographic image frame, and the 2 nd blood flow velocity data set and the 2 nd tomographic image frame. The display processing unit 38 then generates ultrasonic image data based on the 2 nd blood flow velocity data set and the 2 nd tomographic image frame, and the 3 rd blood flow velocity data set and the 3 rd tomographic image frame. The display processing unit 38 finally generates ultrasonic image data based on the N-1 th blood flow velocity dataset and the N-1 th tomographic image frame, and the N-1 th blood flow velocity dataset and the N-th tomographic image frame. The display processing unit 38 sequentially displays images based on the respective tomographic image data on the display unit 20.

In the above, the direction in which each particle is moved is defined as a direction indicated by a blood flow velocity vector based on the subsequent blood flow velocity data set. The direction in which each particle is moved may be a direction indicated by a blood flow velocity vector based on the previous blood flow velocity data set.

The actual calculation performed in the above-described buffer injection operation is described below. The position of the particle generated at the center of the inlet 64 at the 2 nd analysis timing is determined as the position of a vector obtained by multiplying the movement time move _ time (1) of the particle movement by the velocity vector from the center of the inlet 64. The first movement time move _ time (1) of the particles is obtained as a value obtained by multiplying the ratio of the remaining inflow amount flow _ rem (1) to the inflow amount flow _ rate at the time of particle generation by the frame time interval flm _ intvl. Here, the remaining inflow amount flow _ rem (1) is the volume of liquid remaining in the liquid source 70 when the buffer container 68 is filled with liquid and the buffer container 68 is initially filled with liquid.

The volume contained in the liquid source 70 at the 1 st resolution timing is the inflow blood flow _ rate. When the buffer capacity is set to flow _ th and the initial amount at the 1 st analysis timing is set to flow _ buf, the remaining inflow amount flow _ rem (1) is calculated by (equation 1).

(math formula 1)

flow_rem(1)＝flow_rate-(flow_th-flow_buf)

The movement time move _ time (1) of the initial particle is calculated by (equation 2).

(math figure 2)

move_time(1)＝flow_rem(1)/flow_rate×flm_intvl

The position at the 2 nd analysis timing of the particles initially generated at the center of the inflow port 64 is the position (x (1), y (1)) of the initial particles when the liquid source 70 is empty. The position (x (1), y (1)) is calculated according to (equation 3). Here, (xnk, ynk) is the position coordinates of the center of the inflow port 64, and (vxnk, vynk) is the blood flow velocity vector at the center of the inflow port 64. The blood flow velocity vector is a vector based on the subsequent blood flow velocity data set.

(math figure 3)

x(1)＝xnk+vxnk·move_time (1)

y(1)＝ynk+vynk·move_time (1)

Therefore, the first particle is drawn at the position on the tomographic image obtained by (equation 3) at the 2 nd analysis timing.

Let j be an integer of 2 or more, and the volume frew _ rem (j) of the liquid source 70 in which the jth particle is generated is calculated by (equation 4).

(math figure 4)

flow_rem(j)＝flow_rem(j-1)-flow_th

Further, the jth particle is not generated under the condition that flow _ rem (j-1) < flow _ th.

The position of the jth particle generated at the center of the inlet 64 at the 2 nd analysis timing is determined as the position of a vector obtained by multiplying the moving time move _ time (j) of the particle by the velocity vector, moving from the center of the inlet 64. The movement time move _ time (j) of the j-th particle is calculated by (equation 5).

(math figure 5)

move_time(j)＝flow_rem(j)/flow_rate×flm_intvl

The position (x (j), y (j)) at the 2 nd analysis timing of the particle generated at the center of the inlet 64 is the position (x (j), y (j)) of the jth particle at which the liquid source 70 is empty. The position is calculated according to (equation 6).

(math figure 6)

x(j)＝xnk+vxnk·move_time (j)

y(j)＝ynk+vynk·move_time (j)

Therefore, the jth particle is drawn at the position on the tomographic image obtained by (equation 6) at the 2 nd analysis timing.

The storage device 26 stores a buffer injection operation program for executing the calculations according to the above-described (expression 1) to (expression 6). The arithmetic device 18 virtually constitutes the particle position arithmetic part 32 by executing a buffer injection arithmetic program, and finds the position of each particle on the tomographic image.

The storage device 26 stores an ultrasonic image generation program including such a buffer injection calculation program. The computing device 18 executes an ultrasonic image generation program to display an ultrasonic image on the display unit 20. The program causes the arithmetic device 18 to execute the following processes (i) and (ii).

(i) Processing for acquiring a blood flow velocity vector set at a flow inlet on the analysis target region; and a process of obtaining an inflow blood flow volume flowing from the inflow port during a period from the 1 st analysis timing to the 2 nd analysis timing based on the blood flow velocity vector.

(ii) And a process of generating an ultrasonic image at the 2 nd analysis timing by performing a buffer injection operation based on the inflow blood flow volume and the blood flow velocity vector. Here, the buffer injection operation is as follows: the positions of particles appearing in an ultrasound image are determined based on the inflow blood flow volume, a predetermined buffer volume, and a blood flow velocity vector, and an ultrasound image in which the particles are made to appear at the determined positions is generated. The buffer capacity is a value for determining the distance between particles based on the inflow blood flow when a plurality of particles are present in the ultrasound image.

Fig. 5 and 6 schematically show ultrasonic images in which the respective particles 80 indicating the flow rate of the blood flowing in at that moment are drawn on the tomographic image. In the ultrasound image shown in fig. 5, the heart 50 is depicted in an early stage of the expansion of the left ventricle 54. In the ultrasound image shown in fig. 6, the heart 50 is depicted just before the end of the dilation of the left ventricle 54.

In fig. 5 and 6, the flow rate of blood from the mitral valve 56 to the left ventricle 54 is represented by a plurality of particles 80 aligned in the direction from the mitral valve 56 to the left ventricle 54. In these figures, the greater the number of particles 80 aligned in the direction from the mitral valve 56 toward the left ventricle 54, the greater the flow rate of blood. Shown in these figures are: the more the distal end of the mitral valve 56, the larger the flow rate of blood, and the more the valve annulus, the smaller the flow rate of blood. In addition, it shows: the flow rate of blood flowing into the left ventricle 54 immediately before the end of diastole is smaller than the flow rate of blood flowing into the left ventricle at the initial stage of diastole.

As described above, according to the ultrasonic diagnostic apparatus according to the embodiment of the present invention, the flow rate of blood at the inlet, which is a region having a wide width, is appropriately indicated so as to be easily grasped by the user. The blood flow opening set by the user is divided into a plurality of inlets, and the flow rate of blood is obtained for each of the plurality of inlets. This makes it possible to appropriately show the distribution of the flow rate of blood in the analysis target region so as to be easily grasped by the user. Further, in each of the buffer injection operations of the repeatedly executed particle position operations, the remaining amount obtained by the previous buffer injection operation is set as the initial amount in the next buffer injection operation. This improves the continuity of the sequentially generated ultrasonic images, and facilitates the user to grasp the flow rate of blood at the inlet.

The particle position calculating unit 32 may determine the number of particles (total number of particles) generated in the blood flow opening 61 from the generation of the 1 st tomographic image frame to the generation of the J-th tomographic image frame to be displayed. Wherein J is an integer of 2 to N. The display processing unit 38 may display the total particle count on the display unit 20 together with the tomographic image. The display processing unit 38 may obtain the total inflow rate together with the total particle count, and display the total inflow rate together with the tomographic image on the display unit 20. The total inflow rate is the volume of blood flowing into the blood flow opening 61 from the generation of the 1 st tomographic image frame to the generation of the J-th tomographic image frame to be displayed.

The particle position calculating unit 32 may determine the number of particles (inter-frame particle number) generated in the blood flow opening 61 from the generation of the J-1 th tomographic image frame to the generation of the J-th tomographic image frame. The display processing unit 38 may display the inter-frame particle count on the display unit 20 together with the tomographic image. The display processing unit 38 may also determine the inter-frame inflow amount together with the inter-frame particle number, and display the inter-frame inflow amount together with the tomographic image on the display unit 20. The inter-frame inflow amount is the volume of blood flowing from the blood flow opening 61 during the period from the generation of the J-1 th tomographic image frame to the generation of the J-th tomographic image frame.

In the above, the embodiment of performing the VFM based on the particle position calculation on the blood flow velocity data set and the tomographic image frame sequentially generated at the frame time interval has been described. When interpolation processing is performed on a blood flow velocity dataset and a tomographic image frame that are sequentially generated at a frame time interval to generate an interpolation dataset and an interpolation frame for the blood flow velocity dataset and the tomographic image frame, VFM may be executed so as to include the interpolation dataset and the interpolation frame. That is, VFM based on particle position calculation may be performed on a sequence of blood flow velocity data sets in which interpolation data sets are inserted on the time axis and on tomographic image frames in which interpolation frames are inserted on the time axis.