JPH0679601B2 - Ultrasonic diagnostic equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ultrasonic diagnostic apparatus that accurately measures and displays a motion velocity vector distribution of a moving part in a living body.

2. Description of the Related Art A conventional ultrasonic diagnostic apparatus capable of measuring the motion velocity of a moving part in a living body and displaying it in two dimensions is known, for example, in the configuration described in Japanese Patent Laid-Open No. 58-188433. . This method obtains the phase change of the received signal due to the Doppler effect of ultrasonic waves from the autocorrelation function, calculates the motion velocity, and repeats this measurement while shifting the measurement site by a small amount,
The velocity distribution image of the moving part in the living body is two-dimensionally displayed on the display device.

Problems to be Solved by the Invention However, since the conventional method uses the Doppler effect of the ultrasonic wave, only the component of the moving direction of the ultrasonic wave of the moving speed is measured, and the moving direction of the ultrasonic wave of the moving speed is measured. On the other hand, since the component in the direction orthogonal to that cannot be measured, not only the true motion velocity cannot be measured, but also the direction of the motion velocity originally as a vector quantity cannot be known. Furthermore, for example, when a sector type probe is used to perform a sector scan to display a two-dimensional motion velocity by a conventional method, as shown in FIG. 7, the motion velocity of a fluid flowing uniformly from left to right is obtained. On the left side of the figure, it is impossible to detect the frequency shift due to the Doppler effect in the direction of approaching the transducer in the traveling direction of the ultrasonic beam, the direction of moving away from the transducer in the right side of the figure, and in the center part. There is a problem that the motion is displayed as if the motion is not performed at all, and the motion speed is displayed that is far from the actual motion.

The present invention solves the above-mentioned problems of the prior art, and a moving speed component in a direction orthogonal to the moving direction of an ultrasonic wave of a moving speed of a moving portion in a living body and a moving speed of the ultrasonic wave of a moving speed. It is an object of the present invention to provide a technique that enables simultaneous measurement of a motion velocity component in a direction and two-dimensional vector display of a motion velocity of a moving part in a living body which is originally a vector amount as a vector amount.

Means for Solving the Problems The present invention is directed to a parallel wave receiving device that simultaneously wave-receives and phases a plurality of channels, an adder that alternately inverts and adds the sign of a received signal of each channel, and a frequency spectrum. A first frequency analyzer for determining and a first speed calculator,
The above object is achieved by providing a complex signal converter, an autocorrelator or a second frequency analyzer, and a second velocity calculator.

Operation According to the present invention, with the above-described configuration, the sign of the received signal of each channel of the parallel receiving circuit is alternately inverted and added, and the frequency spectrum of the added received signal is calculated by the first frequency analyzer. . This means that the change amount of the received signal between the channels caused by the movement of the moving part in the living body in the direction (channel direction) orthogonal to the traveling direction of the ultrasonic beam is obtained as a frequency spectrum. From the frequency spectrum, the motion velocity in the direction orthogonal to the traveling direction of the ultrasonic beam in the moving part in the living body is obtained. At the same time, the change in the phase of the received signal due to the Doppler effect is calculated from the phase of the autocorrelation function of the received signal,
Alternatively, it is obtained by directly performing frequency analysis with a second frequency superanalyzer, and by calculating the movement velocity component of the moving direction of the ultrasonic beam in the moving part inside the living body from this, the movement inside the living body is taken as a vector quantity. Can be measured.

Embodiments Embodiments of the present invention will be described below with reference to the drawings. In all the drawings for explaining the embodiments, those having the same functions are designated by the same reference numerals and their repeated description will be omitted.

1 to 3 are views for explaining one embodiment of the present invention, and FIG. 1 is a block diagram showing a schematic configuration of the ultrasonic diagnostic apparatus, FIG. 2 and FIG. FIG. 3 is a block diagram showing an example of a detailed configuration of a parallel wave receiving circuit.

In FIG. 1, reference numeral 1 is a probe for transmitting and receiving an ultrasonic beam. As shown in FIG. 2, n strip-shaped transducers (hereinafter referred to as elements) are arranged in an array. A transducer is formed by arranging them side by side. The elements # 1 to #n of the probe 1 are connected to the switching circuit 2.

The switching circuit 2 sequentially selects k elements (10 elements in FIG. 2) from the n elements # 1 to #n during the transmission time, and the k elements are selected during the transmission time. The elements are connected to the wave transmission circuit 3, and during the reception time, j elements (in FIG. 2, in FIG. 2) of m elements (4 elements in FIG. 2) out of n elements # 1 to #n. 4) are connected to the receiving amplifier 4 so as to select adjacent channels.

The wave sending circuit 3 not only generates a wave sending pulse, but also controls the phase of the wave sending pulse to control the ultrasonic beam sent from the k elements. Reference numerals 5 to 8 are wave-reception phasing circuits, which control the phase of the wave-reception signal from each element forming the j channels to control the directivity at the time of reception. Reference numeral 9 is an adder for adding the received signals phase-matched by the wave rectifying circuit so that the signs of the received signals are alternately inverted, 10 is a phase shifter for phase-shifting the reference pulse signal by 90 °, and 11 is an adder 9. A mixer that mixes the added received signal and the reference pulse signal of the transmitted signal, 12 is a mixer that mixes the 90 ° phase-shifted reference pulse signal and the received signal, and 13 and 14 are mixers of the mixers 11 and 12. Low-pass filter (LPF) that filters output and outputs as phase detection signal, 15 and 16 are A / D converters that convert LPF phase detection signal to digital signal, and 17 and 18 are phase detection signals converted to digital signal A canceller that removes low-frequency components of the signal,
Reference numeral 19 is a frequency analysis device for calculating the frequency spectrum of the phase-detected received signal, and 20 is orthogonal to the traveling direction of the ultrasonic beam of the moving part inside the living body, based on the frequency spectrum obtained by the frequency analysis device 19. It is a speed calculation circuit that calculates a motion speed component of a direction. An image memory 21 temporarily stores the motion velocity calculated by the velocity calculation circuit 20. 22 is a D / A converter, 23 is a switching circuit, 24 is a display device, 25
Is a wave reception phasing circuit, which phase-matches the reception signal for displaying a B-mode image. 26 is a detector, 27 is an A / D converter, 28
Is an image memory, 29 is a D / A converter, and 30 is a switching circuit. 1
01 is a phase shifter, which shifts the reference pulse signal of the transmitted signal by 90 °. 102 and 103 are mixers, 102 mixes the received signal whose phase is matched by the wave phasing circuit 27, and 103 is the phase shifter 1
In 01, the reference pulse signal and the received signal that are 90 ° phase-shifted are mixed. Reference numerals 104 and 105 are low-pass filters (LPFs) that filter the outputs of the mixers 102 and 103 and output as a phase detection signal. Reference numerals 106 and 107 are A / D converters, which convert the phase detection signal obtained by the LPF into a digital signal. Reference numerals 108 and 109 denote cancellers that remove low-frequency components of the phase detection signal converted into a digital signal. 110 and 111 are delay devices, which delay a part of the phase detection signal. Reference numeral 112 calculates an autocorrelation function from the signal phase-detected by the autocorrelator. A second velocity calculator 113 calculates the motion velocity component in the traveling direction of the ultrasonic beam in the motion part from the autocorrelation function.

The operation of the above configuration will be described below.

FIG. 2 shows an embodiment of a parallel wave receiving circuit in which four channels receive waves in parallel and simultaneously, and each channel is composed of four elements. At the time of receiving waves, each channel is configured to be shifted by 2 elements, and a total of 10 elements are receiving at the same time. That is, the outputs of the wave receiving and phasing circuits 5 to 8 correspond to the outputs of the respective channels. Here, the number of channels to receive simultaneously, the number of elements forming each channel, and the shift pitch of adjacent channels can be arbitrarily set, and as shown in FIG. 3, the number of channels to receive simultaneously is 4. The number of elements forming each channel may be eight, and the shift pitch between adjacent channels may be one element. In FIG. 2, each element selected by the switching circuit 2 is connected to the corresponding wave-receiving amplifier 4, and the output of the wave-receiving amplifier 4 is the wave-receiving phasing circuit 5.
8 is input, the output of the receiving amplifier 4 is input to the tap of the delay device having the delay time corresponding to the element that is the input of the receiving amplifier 4 in order to control the directivity at the time of receiving the wave. Then, the phase of each channel is controlled and added. Adjacent channels are arranged at a pitch of two element intervals, and spatially two element interval information can be fetched in parallel for the number of channels and simultaneously.

On the other hand, at the time of wave transmission, at least all the elements connected to the channels that receive waves at the same time are transmitted by the wave transmission circuit 3
And an ultrasonic beam whose directivity is controlled according to the transmission pulse whose phase is controlled by the transmission circuit 3 is transmitted from each element.

In FIG. 1, the wave reception signals of the respective channels at the same time, which are output from the wave reception phasing circuits 5 to 8, are added by the adder while inverting the signs. A part of the received wave signal added by the adder is mixed with the reference pulse signal of the transmitted wave signal by the mixer 11, and converted into a phase detection signal by the LPF 13.
The other part is mixed with the reference pulse signal of the transmission signal whose phase is shifted by 90 ° by the mixer 12, converted into the phase detection signal by the LPF 14, and converted into the digital signal by the A / D converters 15 and 16, respectively. However, the digitally detected phase detection signals are 90 ° phase-shifted from each other, that is,
It is a complex phase detection signal having a complex conjugate relationship. The cancellers 17 and 18 remove low-frequency components, so-called clutter components, which are included in the phase detection signal and are associated with body movements of in-vivo tissues. The frequency spectrum of the complex phase detection signal from which the clutter component has been removed is calculated by the cancellers 17 and 18 input to the frequency analysis device 19. In the calculation of this frequency analysis, the received signal in each channel of the ultrasonic beam due to the movement in the living body is f
(X), a function indicating addition while inverting the sign of the received signal is expressed as h (x). h (x) is a function that changes into a rectangular wave shape at an interval equal to the channel pitch of the parallel wave receiving device, as shown in FIG. 5 (a). The received signal added by the adder is g (x), and G
Fourier transform of (ω) into g (x), H (k), F
If (k) is the Fourier transform of h (x) and f (x), respectively, the following relationship holds.

Here, V is a motion velocity in a direction orthogonal to the traveling direction of the ultrasonic beam of the moving part in the living body to be measured, and H (k) represents a complex conjugate of H (k), As shown in FIG. 5 (b), there is a relationship showing a sharp peak at k = 2π / p, (p is the pitch of the channel interval).
On the other hand, since F (k) is a broad function, G (ω) represented by its product is a function showing a sharp peak. Further, here, the frequency spectrum is calculated by the complex phase detection signal at the time interval of the pulse repetition period T of the n ultrasonic beams, and the number i is the scanning line for forming the B-mode image. From the number N, the pulse repetition period T of the ultrasonic beam, and the frame rate F of the image, it is determined by the following relational expression iTNF = 1 (2). In the speed calculator 20, ω _P that gives the peak of the frequency spectrum is calculated from this frequency spectrum. However, due to the limitation of the equation (2), i is made sufficiently large in order to give the ultrasonic diagnostic image real-time characteristics. Since it cannot be obtained and the frequency resolution becomes coarse, it is obtained as the frequency spectrum moment. Ω _P = ω · | G (ω) | (3) From this ω _P , it is orthogonal to the traveling direction of the ultrasonic beam of the moving part in the living body. Direction velocity component V is It is possible to measure and display the movement velocity of the living body movement portion as a vector amount.

As is clear from the above description, according to the present embodiment, the plurality of adjacent channels receive the signals in parallel and simultaneously, and the adder adds the received signals of the respective channels while alternately inverting the signs. From the frequency spectrum obtained by the frequency analyzer, it is possible to obtain the motion velocity component in the direction orthogonal to the traveling direction of the ultrasonic beam in the moving part in the living body. On the other hand, a part of the received signal whose phase has been matched by the received wave phasing circuit 29 is mixed with the reference pulse signal of the transmitted signal by the mixer 102 and converted into a phase detection signal by the LPF 104. The other part is mixed with the reference pulse signal of the transmission signal whose phase is shifted by 90 ° by the mixer 103, converted into a phase detection signal by the LPF 105, and converted into a digital signal by the A / D converters 106 and 107, respectively. However, the digital-converted phase detection signals are complex phase detection signals having a 90 ° phase-shifted relationship, that is, a complex conjugate relationship. The cancellers 108 and 109 remove the clutter component. A part of the complex phase detection signal from which the clutter component has been removed by the cancellers 108 and 109 is delayed by the delay devices 110 and 111, and the delayed complex phase detection signal and the uncorrelated complex phase detection signal are input to the autocorrelator 112. Then, the autocorrelation function as a complex quantity is obtained. Now, letting the real part of the autocorrelation function be Cr and the imaginary part be Ci, there is the following relationship with the frequency shift fd due to the Doppler effect of the ultrasonic beam in the moving part in the living body.

Here, T is the pulse repetition period of the ultrasonic beam. Since the Doppler effect is the frequency shift of the ultrasonic beam due to the motion velocity component in the traveling direction of the ultrasonic beam in the moving part inside the living body, in the velocity calculator 113, from the autocorrelation function calculated by the autocorrelator 112 ( From the relation of equation (4), fd can be obtained, and from this, the motion velocity component of the moving direction of the ultrasonic beam in the moving part inside the living body can be calculated,
The motion velocity component inside the living body as vector information can be obtained.

As described above, according to the present embodiment, the moving direction of the ultrasonic beam in the moving part inside the living body and the moving velocity component in the direction orthogonal thereto can be measured at the same time, and can be measured and displayed as the vector of the state of the moving part inside the living body.

Next, a second embodiment of the present invention will be described.

FIG. 4 is a block diagram showing the outline of the ultrasonic diagnostic apparatus according to the second embodiment of the present invention.

4 is different from FIG. 1 in that a frequency analyzer 201 is provided instead of the delay units 110 and 111 and the autocorrelator 112. In this frequency analyzer 201, by directly frequency-analyzing the complex phase detection signal, the frequency shift due to the Doppler effect of the ultrasonic beam due to the moving part in the living body is directly calculated, and the traveling direction of the ultrasonic beam in the moving part within the living body is calculated. The motion velocity component of is calculated.

EFFECTS OF THE INVENTION As described above, the present invention includes a parallel wave phasing circuit that simultaneously wave-phases a plurality of channels, an adder that adds the received signals between the channels while alternately inverting them, and A circuit for converting the received signal into a complex phase detection signal, a frequency analyzer for calculating the frequency spectrum, and a speed calculator for calculating the speed of a moving part in the living body from the frequency spectrum are provided. It is possible to obtain the motion velocity component in the traveling direction of the ultrasonic pulse beam of a part, and to measure and display the accurate state of the motion part in the living body as vector information that could not be measured and displayed by the conventional device. It is possible to provide an ultrasonic diagnostic apparatus capable of performing accurate diagnosis with a very easy-to-understand display, and its effect is great.

[Brief description of drawings]

FIG. 1 is a block diagram showing an outline of an ultrasonic diagnostic apparatus according to a first embodiment of the present invention, and FIG. 2 is a block showing details of an embodiment of a parallel wave receiving circuit according to the first embodiment of the present invention. FIG. 3 is a block diagram showing the details of another embodiment of the parallel wave receiving circuit in the first embodiment of the present invention, and FIG. 4 is an outline of the ultrasonic diagnostic apparatus in the second embodiment of the present invention. FIG. 5 (a) is a diagram showing the characteristics of the adder, FIG. 5 (b) is a diagram showing the characteristics of the adder in the frequency domain, and FIG. 6 is a conventional ultrasonic diagnosis. It is a figure for explaining a problem of a device. 1 ... probe, 2 ... switching circuit, 3 ... transmission circuit, 4 ...
… Receiver amplifier, 5-8 …… Receiver phasing circuit, 9 …… Adder, 10 …… 90 ° phaser, 11,12 …… Mixer, 13,14 …… LP
F, 15,16 …… A / D converter, 17,18 …… Canceller, 19 ……
Frequency analyzer, 20 ... speed calculation circuit, 21 ... image memory, 22 ... D / A converter, 23 ... switching circuit, 24 ... display device, 25 ... receiving wave phasing circuit, 26 ... Detector, 27 …… A / D converter, 28 …… Image memory, 29 …… D / A converter, 30 …… Switching circuit, 101 …… 90 ° phase shifter, 102,103 …… Mixer, 104,
105 …… LPF, 106,107 …… A / D converter, 108,109 …… Canceller, 110,111 …… Delayer, 112 …… Autocorrelator, 113
...... Speed calculation circuit, 201 …… Frequency analyzer.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Nobuaki Furuya 3-10-1 Higashisanda, Tama-ku, Kawasaki-shi, Kanagawa Matsushita Giken Co., Ltd. (56) Reference JP-A-61-100236 (JP, A) Kai 60-58131 (JP, A) JP 1-99538 (JP, A) JP 1-99539 (JP, A)

Claims (2)

[Claims] Claim: What is claimed is: 1. An ultrasonic pulse beam is transmitted to a living body at a constant repetition cycle, the reflected wave is received, the received signal is amplified, and the amplified received signal is transmitted through a plurality of channels. A parallel wave receiving circuit that simultaneously wave-receives and phase-matches, an adder that alternately inverts the sign of the wave receiving signals of the channels of the parallel wave receiving circuit, and adds, and has a frequency that is an integral multiple of the transmission repetition frequency. By mixing a set of complex reference signals having a complex conjugate relationship with each other and the received signal added by the adder,
A first complex signal converter that converts the received signal into a complex signal, a frequency analyzer that calculates the frequency spectrum of the received signal that is converted into a complex signal, and an ultrasonic pulse of the moving part in the living body from the frequency spectrum A first speed calculator for calculating a motion speed in a direction orthogonal to the beam traveling direction,
A second set of a complex reference signal having a frequency that is an integer multiple of the transmission repetition frequency and having a complex conjugate relationship with each other and the amplified received signal are mixed to convert the received signal into a complex signal. A complex signal converter, an autocorrelator for calculating an autocorrelation function of a complex signal by providing a delay time of the complex signal, and a velocity in the traveling direction of an ultrasonic pulse beam of biological motion from the output of the autocorrelator And a second velocity calculator for measuring the velocity vector distribution in the traveling direction of the ultrasonic pulse beam and the direction orthogonal to the traveling direction, and displaying the velocity vector distribution. 2. An ultrasonic pulse beam is transmitted into a living body at a constant repetition period, the reflected wave is received, the received signal is amplified, and the amplified received signal is transmitted through a plurality of channels. A parallel wave receiving circuit that simultaneously wave-receives and phase-matches, an adder that alternately inverts the sign of the wave receiving signals of the channels of the parallel wave receiving circuit, and adds, and has a frequency that is an integral multiple of the transmission repetition frequency. By mixing a set of complex reference signals having a complex conjugate relationship with each other and the received signal added by the adder,
The first complex signal converter that converts the received signal into a complex signal, the first frequency analyzer that calculates the frequency spectrum of the received signal converted into a complex signal, and the A first velocity calculator for calculating the motion velocity in the direction orthogonal to the traveling direction of the ultrasonic pulse beam, and a set of complex reference signals having a frequency that is an integer multiple of the transmission repetition frequency and having a complex conjugate relationship with each other. A second complex signal converter that mixes the amplified received signal with each other to convert the received signal into a complex signal, and a second complex signal frequency delay calculating delay time of the complex signal. And a second velocity calculator for calculating the velocity in the traveling direction of the ultrasonic pulse beam of biological movement from the output of the second frequency analyzer, and the traveling direction of the ultrasonic pulse beam and It Orthogonal ultrasonic diagnostic apparatus characterized by measuring and display of the direction of the velocity vector distribution.