JPH11262489A - Ultrasonography and ultrasonograph - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve tracking property of an object by transmitting ultrasonic waves to a subject body, three-dimensionally tracking the location of the object moving within the subject body based on echoes and seeking information on movement of the object based on a change in the location of the object. SOLUTION: This device receives echoes from a subject body 4 by a transmitting/receiving part 6 with which an ultrasonic probe 2 abutted on the subject body 4 is connected. At this time, a sector scan for a three-dimensional area is performed by successive sound ray in the transmitting/receiving part 6 and an echo signal on each sound ray is received. An echo signal on each sound ray is stored as digital data in an echo memory of a data processing part 10. Based on this stored echo data, tomographic images for each two-dimensional area within the three-dimensional area, that is, B-mode images are generated. An operator selects the B-mode images of desired cross section and makes a display part 16 display the images. Next, a movement measurement for an indicated point by a cursor on the displayed images is started.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic diagnostic method and apparatus, and more particularly, to an ultrasonic diagnostic method and apparatus for obtaining information on the dynamics of a moving object in a subject.

[0002]

2. Description of the Related Art Japanese Patent Laying-Open No. 10-5226 discloses an ultrasonic diagnostic apparatus for measuring a velocity waveform of a minute movement superimposed on myocardial tissue pulsating with a large amplitude.
This device radiates ultrasonic waves toward an object inside the body, detects the ultrasonic signal reflected from the object, analyzes the detected signal, and measures the position and movement of the object. It is.

This ultrasonic diagnostic apparatus determines the instantaneous position of an object using the amplitude and phase of a detection signal in order to measure the position and movement of the object, and determines the instantaneous position of the object based on the heart beat. Tracking large amplitude displacement motion
ing)) a large-amplitude displacement motion analyzing means, and a micro-vibration analyzing means for obtaining a motion velocity waveform of a micro-vibration superimposed on the large-amplitude motion of the object based on the sequential position of the object obtained by tracking. It has.

The large-amplitude displacement motion analyzing means has a constraint that the waveforms of the two reflected waves with respect to the ultrasonic waves radiated at time t and time t + ΔT, respectively, do not change in amplitude but only in phase and reflection position. Originally, the phase difference is detected by the least square method.

[0005]

In the above-described apparatus, the object can be tracked only in the direction of ultrasonic wave radiation, that is, in the depth direction of the subject, and the object is displaced in the lateral direction with respect to the ultrasonic wave radiation direction. In such a case, there is a problem that tracking cannot be performed and measurement becomes impossible or inaccurate.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to realize an ultrasonic diagnostic method and apparatus excellent in tracking of an object.

[0007]

Means for Solving the Problems (1) According to a first aspect of the present invention for solving the above-mentioned problems, an ultrasonic wave is transmitted to a subject and the position of the object moving within the subject based on the echo is determined by three. An ultrasonic diagnostic method comprising: dimensionally tracking and obtaining information on the dynamics of the object based on a change in the position of the object.

(2) A second aspect of the present invention for solving the above-mentioned problem is that the ultrasonic wave is transmitted to the subject and the position of the moving object in the subject is tracked three-dimensionally based on the echo. And an information processing unit for obtaining information on dynamics of the object based on a change in the position of the object tracked by the tracking unit.

(3) A third invention for solving the above-mentioned problem is that the tracking means utilizes two-dimensional cross-correlation of a C-mode image for three-dimensional tracking of the position of the object. The ultrasonic diagnostic apparatus according to claim 2, wherein:

(4) A fourth aspect of the present invention for solving the above-mentioned problems is that the tracking means includes a two-dimensional image for each of two B-mode images whose scanning planes cross each other for three-dimensional tracking of the position of the object. 3. The ultrasonic diagnostic apparatus according to claim 2, wherein dimensional cross-correlation is used.

In any one of the first to fourth inventions, the three-dimensional tracking of the position of the object utilizes the transmission and reception of ultrasonic waves by a two-dimensional array of ultrasonic transducers. This is preferable in that a high-speed displacement is tracked.

(Operation) In the present invention, tracking of an object moving in a subject is performed three-dimensionally,
The dynamic measurement is performed by following not only the displacement of the object in the depth direction of the subject but also the displacement in the lateral direction.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiment.

FIG. 1 shows a block diagram (bloc) of an ultrasonic diagnostic apparatus.
k) Show the figure. This device is an example of an embodiment of the present invention. The configuration of the present apparatus shows an example of an embodiment relating to the apparatus of the present invention. An example of an embodiment of the method of the present invention is shown by the operation of the present apparatus.

The configuration of the present apparatus will be described. As shown in FIG. 1, the present apparatus has an ultrasonic probe (probe) 2. The ultrasonic probe 2 is in contact with the subject 4 and is used for transmitting and receiving ultrasonic waves. The ultrasonic probe 2 includes an ultrasonic transducer 530 as shown in FIG.
Are provided.

The two-dimensional array 532 is, for example, 128 × 12
A matrix (mat) of eight ultrasonic transducers 530
rix). The direction of one side of the matrix is x, and the direction of the other side is y. Each ultrasonic transducer 530 is made of a piezoelectric material such as PZT (lead zirconate (Zr) titanate (Ti)) ceramics.

The ultrasonic probe 2 is connected to a transmitting / receiving unit 6. The transmitting / receiving unit 6 supplies a drive signal to the ultrasonic probe 2 to transmit ultrasonic waves into the subject 4. The transmission / reception unit 6 also receives an echo from the subject 4 that the ultrasonic probe 2 has received.

FIG. 3 shows a block diagram of the transmission / reception section 6. In the figure, a transmission timing (timing) generating circuit 602
Is configured to periodically generate a transmission timing signal and input the transmission timing signal to a transmission beamformer (beamformer) 604.

The transmission beamformer 604 performs transmission beamforming based on the transmission timing signal.
ming) signal, that is, a plurality of drive signals for driving a plurality of ultrasonic transducers in the array of ultrasonic transducers with a time difference, and a transmission / reception switching circuit 606.
Is entered.

The transmission / reception switching circuit 606 inputs a plurality of drive signals to a selector 608. The selector 608 selects a plurality of ultrasonic transducers forming a transmission aperture from an array of ultrasonic transducers, and applies a plurality of drive signals to them.

The plurality of ultrasonic transducers respectively generate a plurality of ultrasonic waves having a phase difference corresponding to a time difference between a plurality of drive signals. An ultrasonic beam is formed by wavefront synthesis of those ultrasonic waves. The transmitting direction of the ultrasonic beam is determined by the traveling direction of the combined wavefront.

The transmission of the ultrasonic beam is repeatedly performed at predetermined time intervals by a transmission timing signal generated by the transmission timing generation circuit 602. The transmission direction of the ultrasonic beam is sequentially changed by switching the time difference between the plurality of drive signals. Thereby, the inside of the subject 4
Scanning is performed by sound rays formed by the ultrasonic beam. That is, the inside of the subject 4 is scanned in a sound ray sequence.

The selector 608 selects a plurality of ultrasonic transducers forming a receiving aperture from the array of ultrasonic transducers, and sends a plurality of echo signals received by the ultrasonic transducers to the transmission / reception switching circuit 606. To be entered.

The transmission / reception switching circuit 606 inputs a plurality of echo signals to the reception beamformer 610. The receive beamformer 610 adds a time difference to the plurality of echo signals to adjust the phase, and then adds them to form a receive beamforming, that is, an echo receive signal on the receive sound ray. . By switching the time difference given to the plurality of echo signals, the received sound ray is also scanned in accordance with the transmission. An output signal of the reception beam former 610, that is, an echo reception signal on the reception sound ray is subjected to quadrature detection by the quadrature detection circuit 612.

The transmission timing generation circuit 602 to the reception beam former 610 are controlled by a control unit 18 described later. For example, scanning as shown in FIG. 4 is performed by the ultrasonic probe 2 and the transmission / reception unit 6. That is, as shown in FIG.
A sound ray 202 emitted in the z direction from 0 is a fan-shaped two-dimensional area 2
06 in the θ direction, so-called sector scan (sec.
tor scan) is performed.

The scanning in the θ direction is performed by, for example, a two-dimensional array 53.
2 by sequentially switching the beam forming in the x direction. Meanwhile, the two-dimensional array 532
The beamforming in the y-direction at is kept constant. Each time the scanning of one two-dimensional area 206 is completed, y
The same θ scanning is repeated while changing the beam forming in the direction by one step. Thereby, the two-dimensional area 206 is sequentially moved in the φ direction perpendicular to the θ direction and the z direction, and scanning of the three-dimensional area is performed.

The transmission / reception unit 6 is connected to the data processing unit 10 and inputs the echo reception signal for each sound ray to the data processing unit 10 as a digital signal. The data processing unit 10 is an example of an embodiment of a tracking unit according to the present invention. It is also an example of an embodiment of the information processing means in the present invention.

The data processing unit 10, as shown in FIG.
A data processor 550, an echo memory 552, a data memory 554, and an image memory 556 are provided. Data processing processor 5
50, the echo memory 552, the data memory 554, and the image memory 556 are connected by a bus 558.

The digital data input from the transmitting / receiving unit 6 is stored in the echo memory 552. As a result, echo data is stored in the echo memory 552 for each sound ray.

The data processor 550 performs predetermined data processing on the data in the echo memory 552. Data processor 550 also performs data processing on data in data memory 554 and image memory 556. By this data processing, tracking and dynamic measurement of the object in the subject 4 are performed. Further, an image is generated based on the echo data stored in the echo memory 552.
The data processing will be described later.

A display unit 16 is connected to the data processing unit 10. Display information is input to the display unit 16 from the data processing unit 10, and the information is displayed as an appropriate image such as an image, a numerical value, a waveform diagram, or a graph.

The transmitting / receiving unit 6, the data processing unit 10, and the display unit 16 are connected to a control unit 18. Control unit 1
Numeral 8 gives a control signal to each of these parts to control the operation. Further, the control unit 18 is configured to receive various notification signals from the controlled units.

An operation unit 20 is connected to the control unit 18. The operation unit 20 is operated by the operator, and the control unit 18
The user inputs desired commands and information. The operation unit 20 includes, for example, an operation panel provided with a keyboard and other operation tools.

The operation of the present apparatus will be described. The operator abuts the ultrasonic probe 2 on a desired portion of the subject 4 and operates the operation unit 20 to measure dynamics of a tissue exercising in the body such as a myocardium. The movement measurement is performed under the control of the control unit 18.

The transmitting / receiving unit 6 performs a sector scan on a three-dimensional area in the order of sound rays, and receives echo signals on each sound ray. The echo signal on each sound ray is stored in the echo memory 552 of the data processing unit 10 as digital data. The data processor 550 generates a tomographic image, that is, a tomography (B mode (mode) image) for each of the two-dimensional regions 206 in the three-dimensional region based on the echo data stored in the echo memory 552. Then, the image data is stored in the image memory 556.

From these images, the operator selects a B-mode image of a desired section and displays it on the display unit 16 as shown in FIG. 6, for example. The operator observes the display image and designates an observation point for dynamic measurement on the image 160 of the target object by using, for example, a cursor 162 or the like. Based on this designation, the data processor 550 starts the dynamic measurement. In the dynamic measurement, an observation point moving with the movement (pulsation) of an object is tracked, and a position and a velocity are determined based on an echo on a sound ray (hereinafter referred to as observation sound ray) 208 passing through the observation point. By performing the following.

At the time of tracking, as shown in FIG. 7, the transmission / reception unit 6 scans in the θ and φ directions as seen from the sound ray emission point 200 over a reduced angle range including the observation point 164. The angle range is appropriately set by the operator based on the observation result of the B-mode image so as not to fall below the moving range of the observation point 164 due to the pulsation of the object.

The reduced scanning range is a two-dimensional array 532
However, the scanning may be performed using only a part of the array, such as the 16 × 16 ultrasonic transducers at the center, instead of the whole. This is preferred in streamlining the use of ultrasonic transducers.

Based on the echo data obtained by scanning this angular range, the data processor 550 provides a stereoscopic image of the object, ie, an orthography (C).
A mode image) is generated and stored in the image memory 556. C
The mode image is generated based on, for example, range gate echo data in accordance with the depth (distance in the z direction) of the observation point 164.

The C-mode image irradiates a thick beam of ultrasonic waves to an observation area 166 defined by the θ scan range and the φ scan range,
The echo received at 0 may be range gated, and the data may be generated by two-dimensional Fourier transform. This method is preferable in that only one transmission of the ultrasonic wave for imaging the observation area is required, and the imaging can be speeded up. On the other hand, the above method is preferable in that a scanning device for B-mode imaging can be shared.

When the pulsation of the object includes a motion component in a direction perpendicular to the observation sound ray 208 (hereinafter, referred to as a lateral direction), the image of the object moves in the screen in the C-mode image. Therefore, the data processor 550 determines the 2
A two-dimensional cross-correlation operation is performed between two C-mode images one by one, and the direction and distance of the displacement of the object in the C-mode image are obtained based on the peak of the correlation. The observation sound ray 208 is changed.

That is, the displacement of the observation point 164 in the horizontal direction is detected using the C-mode image, and the observation sound ray 208 is detected.
To follow. Thus, even when the target object moves in the horizontal direction, the observation sound ray 208 is always set to the observation point 16.
4 can be captured.

In this state, the echo data obtained on the observation sound ray 208 is used for dynamic measurement. The dynamic measurement based on the echo data obtained on the observation sound ray 208 is described in
This is performed using the method described in Japanese Patent No. 5226.

The method will be described again. In the data processor 550, the detected waveform y (z, t) of the echo at time t and the ultrasonic pulse (pul
se) and the detected waveform y (z, t + Δ)
For T), the phase shift in between

[0045]

(Equation 1)

Is calculated, and the distance that the object has moved during the time ΔT is calculated. The time ΔT is, for example, 250 μS. At this time, the two waveforms at time t and time t + ΔT are subjected to least-squares matching according to the following expression under the constraint that the amplitude does not change and only the phase and the reflection position change, and the phase deviation between them is performed. Transfer

[0047]

(Equation 2)

Is detected, and the velocity v (t) and the position z (t) are obtained. More specifically, the detection waveform y (z,
t), it is assumed that the object has moved by δz after the time ΔT, and the detection waveforms y (z, t) and y (z, t + Δ
As for T), the amplitude does not change and only the phase is Δθ (δ
z), the matching error α (Δθ (δz), δz) when matching between the two waveforms is given by the following equation.

[0049]

(Equation 3)

Here,

[0051]

(Equation 4)

Means that the sum is calculated for z in the range of the region R. This matching error α (Δθ (δz), δz)
It is necessary to find δz which minimizes the following equation. However, when the waveform y (z, t + ΔT) is moved by δz, the power included in the section R of the waveform may be changed. Is normalized by dividing the right side of the equation (1) by the average power of the two waveforms.

For a given δz, to obtain Δθ (δz) that minimizes the expression (1), α (Δθ (δz), δ
z) is set to 0 by partially differentiating the z) with Δθ (δz), so that the optimum Δθ that minimizes α (Δθ (δz), δz) is obtained.
(Δz) is

[0054]

(Equation 5)

Is obtained. Here, C (δz) is given by the following equation.

[0056]

(Equation 6)

Also,

[0058]

(Equation 7)

Represents the phase of the complex number C (δz). * Represents a complex conjugate. The above calculation is performed every time by changing δz within a certain range, and the minimum matching error is obtained.

[0060]

(Equation 8)

And at that time

[0062]

(Equation 9)

Is calculated. The resulting

[0064]

(Equation 10)

Using the equation, the average speed in this section ΔT

[0066]

[Equation 11]

Can be calculated by the following equation.

[0068]

(Equation 12)

Here, ΔT represents the transmission interval of the ultrasonic pulse (for example, 250 μS), ω0 = 2πf0 represents the angular frequency of the ultrasonic wave, and c represents the sound propagation speed. In addition, this speed value

[0070]

(Equation 13)

By multiplying by ΔT, the displacement of the object at time ΔT

[0072]

[Equation 14]

Is obtained as in the following equation.

[0074]

(Equation 15)

This displacement amount

[0076]

(Equation 16)

By adding to the position z (t) of the object at time t, the position of the object at the next time can be predicted as in the following equation.

[0078]

[Equation 17]

This is the tracking locus z (t).
Thus, the speed of the observation point 164, that is, the time ΔT
Are obtained as in the above equation (4), and the position of the observation point 164 at each time ΔT is obtained as in the above equation (6). That is, information on the dynamics of the object can be obtained. Since the observation sound ray 208 follows the lateral displacement of the observation point 164, the same observation point 164 is always captured, and accurate dynamic information can be obtained.

Further, by combining the thus obtained velocity and position with the amount of lateral displacement obtained by the above cross-correlation, a vector in a three-dimensional space is obtained.
Dynamic information about physical exercise can be obtained. That is, since the above-mentioned lateral displacement is a displacement for each predetermined imaging repetition time, the speed can be obtained based on the displacement. Needless to say, the movement distance is obtained from the displacement amount.

The obtained dynamic information is stored in the data memory 554. Display images such as numerical values, waveform diagrams, and graphs representing the dynamic information are displayed on the display unit 16 via the image memory 556.
And displayed as visible information. Such dynamic information can be effectively used for diagnosing a function, a lesion, or the like of the object.

FIG. 8 shows an example in which the detection of the displacement of the observation point 164 in the horizontal direction is performed using a B-mode image. As shown in the figure, a B-mode image is generated for each of the θ scan plane 210 and the φ scan plane 212 that include the observation point 164 and are perpendicular to each other. θ scan plane 210 and φ scan plane 212
The distance is set as small as possible without falling below the range of movement (pulsation) of the observation point 164.

Two B's on the θ scan plane 210 obtained sequentially
From the mode image, the displacement of the observation point 164 in the θ direction is detected by two-dimensional cross-correlation. Similarly, the displacement of the observation point 164 in the φ direction is detected from the B-mode image of the φ scan surface 212. Then, the observation point 16 is obtained by the vector sum of both displacements.
4 is obtained, and the observation sound ray 20 is adjusted accordingly.
Change 8 This method is preferable because a range gate is not required.

The above is an example in which a two-dimensional array of ultrasonic transducers is used.
Using a two-dimensional array, θ scanning is performed by electron sector scanning by beam forming, and φ scanning is performed by mechanical sector scanning (mechanica
l sector scan). This is preferable in that the scanning device for three-dimensional scanning is simplified.

[0085]

As described above in detail, according to the present invention, it is possible to realize an ultrasonic diagnostic method and apparatus excellent in tracking of an object.

[Brief description of the drawings]

FIG. 1 is a block diagram of a device according to an example of an embodiment of the present invention.

FIG. 2 is a schematic diagram of an ultrasonic transducer array of an ultrasonic probe in an apparatus according to an embodiment of the present invention.

FIG. 3 is a block diagram of a transmission / reception unit in the device according to the embodiment of the present invention;

FIG. 4 is a conceptual diagram of sound ray scanning performed by the apparatus according to an embodiment of the present invention;

FIG. 5 is a block diagram of a data processing unit in the device according to an example of the embodiment of the present invention;

FIG. 6 is a schematic diagram of a display image on a display unit in the device according to an example of the embodiment of the present invention.

FIG. 7 is a conceptual diagram of tracking of an observation point by an apparatus according to an embodiment of the present invention.

FIG. 8 is a conceptual diagram of tracking of an observation point by an apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 2 ultrasonic probe 4 subject 6 transmitting / receiving unit 10 data processing unit 16 display unit 18 control unit 20 operation unit 530 ultrasonic transducer 532 two-dimensional array 602 transmission timing generation circuit 604 transmission beam former 606 transmission / reception switching circuit 608 selector 610 reception Wave beamformer 612 Quadrature detection circuit 550 Data processor 552 Echo memory 554 Data memory 556 Image memory

Claims (4)

[Claims] 1. An ultrasonic wave is transmitted to a subject, and a position of a moving object in the subject is three-dimensionally tracked based on an echo, and the position of the object is changed based on a change in the position of the subject. An ultrasonic diagnostic method, wherein information on the dynamics of the body is obtained. 2. A tracking means for transmitting an ultrasonic wave to a subject and three-dimensionally tracking a position of an object moving in the subject based on an echo, and a tracking means for tracking the position of the object tracked by the tracking means. An ultrasonic diagnostic apparatus, comprising: information processing means for obtaining information on the dynamics of the object based on a change in position. 3. The ultrasonic diagnostic apparatus according to claim 2, wherein said tracking means uses two-dimensional cross-correlation of a C-mode image for three-dimensional tracking of the position of the object. apparatus. 4. The method according to claim 1, wherein the tracking means uses two-dimensional cross-correlation for each of two B-mode images whose scanning planes cross each other for three-dimensional tracking of the position of the object. The ultrasonic diagnostic apparatus according to claim 2, wherein