JPH0199542A - Ultrasonic diagnostic equipment - Google Patents

Abstract

PURPOSE:To make an accurate diagnosis using an easily understandable display, by measuring and displaying a distribution of velocity vector of movement of an organism from output of a first autocorrelator and a second one in both the forward direction and its perpendicular direction of an ultrasonic pulse beam. CONSTITUTION:A parallel wave-receiving circuit for simultaneous wave receiving and phasing through a plurality of channels, an adder 9 for adding received wave signals through respective channels alternately inverting their signs, and an autocorrelation unit 21 for obtaining an autocorrelation function are provided. By the use of them received wave signals through each channel of the parallel wave-receiving circuit are added while their signs are alternately inverted, and an autocorrelation function of added received wave signals is obtained by operation by means of the autocorrelation unit. From change of this autocorrelation function, movement velocity of a moving part in an organism in a direction perpendicular to the forward direction of an ultrasonic beam is obtain by operation. At the same time, a complex signal converter, an autocorrelation unit or a frequency analyzer, and a second velocity arithmetic unit are provided. A movement velocity component of the moving part in the organism in the forward direction of an ultrasonic beam is obtained by operation. Consequently movement in the organism is measured in terms of a vector amount.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an ultrasonic diagnostic apparatus that accurately measures and displays the motion velocity vector distribution of a moving part within a living body.

Conventional Technology Conventional ultrasonic diagnostic equipment is capable of measuring the speed of movement of moving parts within a living body and displaying it two-dimensionally.

For example, a configuration described in Japanese Unexamined Patent Publication No. 58-188433 is known. This method calculates the phase change of the received signal due to the Doppler effect of ultrasound from the autocorrelation function, calculates the speed of movement, and repeats this measurement while shifting the measurement site by a minute amount. The edge of the velocity distribution is displayed two-dimensionally.

Problems to be Solved by the Invention However, since the conventional method utilizes the Doppler effect of ultrasound, it measures only the component of the motion velocity in the direction of travel of the ultrasound. Since the component in the direction orthogonal to the vector cannot be measured, not only the true speed of movement cannot be measured, but even the direction of the speed of movement as a vector quantity cannot be known. Furthermore, when a sector-type probe is used in the conventional method to display two-dimensional motion velocity by scanning the sector, the motion of the fluid flowing uniformly from left to right as shown in Figure 6. The velocity is shown on the left side of the figure in the direction of the ultrasound beam approaching the transducer, on the right side of the figure it is shown in the direction away from the transducer, and in the central part it is impossible to detect the frequency shift due to the Doppler effect. Therefore, there was a problem in that the movement was displayed as if it were not being performed, and the speed of movement was displayed which was completely different from the actual movement.

The present invention solves the above-mentioned problems of the prior art. The object of the present invention is to provide a technique that enables simultaneous measurement of motion velocity components in different directions and display of the motion velocity of a moving part within a living body, which is originally a vector quantity, as a two-dimensional vector.

Means for Solving the Problems The present invention provides a parallel receiving circuit that simultaneously receives and phases signals on multiple channels, an adder that alternately inverts and adds the signs of received signals of each channel, and an autocorrelation system. The above object is achieved by including an autocorrelator for determining a function, a complex signal converter, an autocorrelator or frequency analyzer, and a second velocity calculator.

Operation According to the above configuration, the present invention adds the received signals of each channel of the parallel receiving circuit while inverting the signs alternately, and calculates the autocorrelation function of the added received signals using an autocorrelator. This means that the change in the received signal between each channel caused by the movement speed of the moving part in the living body in the direction (channel direction) perpendicular to the direction of travel of the ultrasound beam is converted into the change in the autocorrelation function. From changes in this autocorrelation function, we can calculate the speed of movement of the moving part inside the living body in a direction perpendicular to the direction of travel of the ultrasound beam, and at the same time, we can calculate the change in phase due to the Doppler effect of the received signal. The movement inside the living body can be determined by calculating the motion velocity component in the direction of movement of the ultrasound beam of the moving part inside the living body by calculating it from the phase of the autocorrelation function of the wave signal or by direct frequency analysis. It can be measured as a vector quantity.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the figures for explaining the embodiments, parts having the same functions are denoted by the same reference numerals, and repeated explanations thereof will be omitted.

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

In Fig. 1, 1 is a probe for transmitting and receiving ultrasonic beams, and as shown in Fig. 2, n strip-shaped transducers (hereinafter referred to as elements) are arranged in an array. A transducer is constructed by arranging them. Each element #1 to I#n of this probe 1 is connected to a switching circuit 2.

This switching circuit 2 sequentially selects elements (10 in Fig. 2) from n elements #1 to #f n during the wave transmission time, and selects the elements only during the wave transmission time. element is connected to the wave transmitting circuit 3, and during the wave reception time, n elements #1 to #n are connected to j elements (Fig. 2) consisting of m elements (4 elements in Fig. 2). In this case, connect to the receiving amplifier 4 so as to select the adjacent channel of 4).

The transmitting circuit 3 not only generates a transmitting pulse, but also performs phase control of the transmitting pulse, thereby controlling the ultrasonic beam transmitted from the above elements. 5 to 8 are reception phasing circuits, which control the directivity during wave reception by controlling the phase of the reception signals from each element constituting the above channels. Reference numeral 9 denotes an adder that adds the received signals phase-matched by the receiver phasing circuit so as to alternately invert the signs; 10 denotes a phase shifter that shifts the reference pulse signal by 90'; and 11 denotes the adder 9. 12 is a mixer for mixing the added received signal and the reference pulse signal of the transmitted signal; 12 is a mixer for mixing the received signal and the reference pulse signal shifted by 90'1ffl phase; 13.
14 is a low pass filter (LPF) that filters the output of the mixers 11 and 12 and outputs it as a phase detection signal;
5.16 is an A/D converter that converts the phase detection signal of the LPF into a digital signal, 17°18 is a canceller that removes the low frequency component of the low frequency signal of the phase detection signal converted to the digital signal, 19.20 is a delay device, 21 is an autocorrelator that calculates an autocorrelation function of the complex phase detection signal, and 22 is an autocorrelator that calculates the autocorrelation function calculated by the autocorrelator 21 to determine the direction of movement of the ultrasound beam in the moving part inside the living body. 23 is an image memory which temporarily stores the motion speed determined by the speed calculation circuit 22. 24 is a D/A converter, 25 is a switching circuit,
Reference numeral 26 denotes a display device, and 27 a reception phasing circuit for phase matching the reception signals in order to display a B-mode image. 28 is a detector, 29 is an A/D converter, 30 is an image memory, and 31 is a D
/A converter, 32 is a switching circuit. A phase shifter 101 shifts the phase of the reference pulse signal of the transmission signal by 90°.

102 and 103 are mixers, 102 is a receiving phasing circuit 27
103 mixes the phase-matched received signal, and a phase shifter 101 mixes the received signal with a reference pulse signal whose phase has been shifted by 90°. 104° and 105 are the mixers 102. a low pass filter (LPF) 106 that filters the output of 103 and outputs it as a phase detection signal;
．． 107 is an A/D converter that converts the phase detection signal obtained by the LPF into a digital signal.

Cancellers 108 and 109 remove low frequency components of the phase detection signal converted into a digital signal.

Delay devices 110 and 111 delay part of the phase detection signal. 112 calculates an autocorrelation function from the signal whose phase has been detected by an autocorrelator. Reference numeral 113 denotes a second velocity computing unit which computes the motion velocity component of the moving part in the traveling direction of the ultrasonic beam from the autocorrelation function.

The operation of the above configuration will be explained in detail below.

Figure 2 shows an example of a parallel receiving circuit in which 4 channels receive waves in parallel and simultaneously, and each channel consists of 4 elements. The elements are arranged in a staggered manner, with a total of 10 elements receiving waves at the same time. That is, receiving wave phasing circuits 5 to 8
Each output corresponds to the output of each channel.

here.

The number of channels that receive waves simultaneously, the number of elements that make up each channel, and the shift pitch between adjacent channels can be set arbitrarily.As shown in Figure 3, the number of channels that receive waves simultaneously is 4, and each 8. Elm l-1a constituting the channel. The deviation pitch of adjacent channels may be made into one element. In Figure 2, switching circuit 2
Each element selected by
8, but in order to control the directionality when receiving waves,
The output of the receiving amplifier 4 is input to a tap of a delay device having a delay time corresponding to the element input to the receiving amplifier 40, and is phase-controlled and added for each channel. Adjacent channels are lined up at a pitch of two elements apart, and it is possible to spatially capture information at two element intervals in parallel for the number of channels, and at the same time.

On the other hand, when transmitting waves, all the elements connected to the channels receiving waves at the same time are connected to the transmitter circuit 3.
A directional, sterilized ultrasonic beam is transmitted from each element in accordance with a transmission pulse whose phase is controlled by the transmission circuit 3.

In FIG. 1, the received signals of each channel at the same time outputted from the receiving wave phasing circuits 5 to 8 are added by an adder while inverting their signs. A part of the received signal added by the adder is mixed with a reference pulse signal of the transmitted signal by a mixer 11.

The LPF 13 converts it into a phase detection signal. The other part is mixed with the reference pulse signal of the transmission signal whose phase has been shifted by 90° in the mixer 12, converted into a phase detection signal in the LPF 14, and then sent to the A/D converter 15.1.
The phase detection signals converted into digital signals are complex phase detection signals having a phase shift of 90 degrees from each other, that is, a complex conjugate relationship. The cancellers 17 and 18 remove low frequency components, so-called clutter components, included in the phase detection signal due to body movements of tissues in the living body. The delay device 19.20 delays a part of the complex phase detection signal from which the clutter component has been removed by the canceller 17.18. Autocorrelator 2
1, the autocorrelation function of the complex phase detection signal is calculated from the delayed complex phase detection signal and the non-delayed complex phase detection signal. In this calculation, the autocorrelation function is calculated using complex phase detection signals at time intervals of pulse repetition period T of n ultrasound beams, and this number n is the scanning line for constructing the B-mode image. It is determined by the following relational expression % (11) from the number N, the pulse repetition period T of the ultrasound beam, and the frame rate F of the image.In the speed calculator 22.

The change in the phase of the autocorrelation function during the pulse repetition period T of the ultrasound beam is calculated by dividing the real part of the autocorrelation function by Srs
If the imaginary part is 81, it is determined by the following equation.

In this autocorrelation calculation, the received signals reflected from the moving parts in the living body are added while inverting the sign of the received signals of adjacent channels arranged at pitch p, and as a result, the transmitted ultrasound During the pulse repetition period T of the beam, the phase shift occurs in the moving part 11 in the direction (channel direction) perpendicular to the traveling direction of the ultrasound beam of the moving part in the living body.
Since the phase changes according to jV, the relationship 2π tick □V T (31) is established, and from this, the motion velocity V of the moving part in the living body in the direction perpendicular to the traveling direction of the ultrasound beam (channel direction) is On the other hand, a part of the received signal whose phase has been matched by the receiving 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. Part of the mixer 10
3, it is mixed with the reference pulse signal of the transmission signal which has been phase shifted by 90, is converted into a phase detection signal by LPF 105, and is converted into a digital signal by A/D converters 106 and 107, respectively. The phase detection signals are complex phase detection signals having a phase shift of 90'fff from each other, that is, a complex conjugate relationship. Cancellers 108 and 109 remove clutter components. A portion of the complex phase detection signal from which clutter components have been removed by the cancellers 108 and 109 is sent to the delay device 110 and 11.
1 and an autocorrelator 1 to which the delayed complex phase detection signal and the non-delayed complex phase detection signal are input.
In step 12, an autocorrelation function as a complex quantity is obtained. Now, assuming that the real part of the autocorrelation function is Cr and the imaginary part is Ci, there is the following relationship between the frequency shift fd due to the Doppler effect of the ultrasound beam at a moving part in the living body.

Here, T is the pulse repetition period of the ultrasound beam. The Doppler effect is a frequency shift of the ultrasound beam due to the motion velocity component in the traveling direction of the ultrasound beam of a moving part inside the living body. 4) From the relationship in the equation, fd is determined, and from this the motion velocity component of the moving part inside the living body in the traveling direction of the ultrasound beam can be determined, and the motion velocity component inside the living body as vector information can be determined.

As described above, according to this embodiment, the traveling direction of the ultrasonic beam of the moving part inside the optical body and the motion velocity component in the direction orthogonal to it can be measured simultaneously, and the state of the moving part inside the living body can be measured and displayed as a vector. .

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

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

The difference in FIG. 4 from FIG. 1 is that the delay device 110% 1
11 and autocorrelator 1120 instead of frequency analyzer 2
01. In this frequency analyzer 201, by directly frequency-analyzing the complex phase detection signal, the frequency shift due to the Doppler effect of the ultrasound beam due to the moving part in the living body is directly calculated, and the traveling direction of the ultrasound beam of the moving part in the living body is calculated. We are looking for the motion velocity component of.

Effects of the Invention As described above, the present invention includes a parallel receiving phasing circuit that simultaneously receives and phases signals on a plurality of channels, an adder that adds received signals between each channel while alternately inverting the signs, By being equipped with a circuit that converts the added received signal into a complex phase detection signal, an autocorrelator that calculates an autocorrelation function, and a speed calculator that calculates the speed of the moving part in the living body from the autocorrelation function. , it is possible to obtain the motion velocity component in the direction in which the ultrasonic pulse beam of the in-vivo moving part advances,
It is now possible to measure and display the exact state of moving parts within the body as vector information, which could not be measured or displayed with conventional devices, making it possible to perform accurate diagnosis with a very easy-to-understand display. An ultrasonic diagnostic device can be provided, and its effects are significant.

[Brief explanation of the drawing]

Fig. 1 is a block diagram schematically showing an ultrasonic diagnostic apparatus according to a first embodiment of the present invention, and Fig. 2 is a block diagram showing details of an embodiment of a parallel wave receiving circuit according to a first embodiment of the present invention. 3 is a block diagram showing details of another embodiment of the parallel wave receiving circuit in the first embodiment of the present invention, and FIG. 4 is a schematic diagram of an ultrasonic diagnostic apparatus in the second embodiment of the present invention. FIG. 5 is a block diagram illustrating the problems of the conventional ultrasonic diagnostic apparatus. 1... Probe, 2... Switching circuit, 31. Transmission circuit, 4
,... Receiving amplifier, 5-8... Receiving phasing circuit, 9...
・Adder, 10...90° phase shifter, 11.12...
Mixer, 13. , 14...LPF, 15.16...
・A/D converter, 17.18... Canceller, 19
．． 20... delay device, 21. , autocorrelator, 22...
・Speed calculator, 23...image memory, 24...D/
A converter, 25... switching circuit, 26... display device,
27... Receiving phasing circuit, 28... Detector, 29...
・A/D converter, 30...image memory, 31...D/
A converter, 32...Switching circuit, 101...90° phase shifter, 102.103...Mixer, 104.105
...LPF, 106.107...A/D converter, 108.109...Canceller, 110.111.
... Delay device, 112 ... Autocorrelator, 113 ... Speed calculation circuit, 201 ... Frequency analyzer. Name of agent: Patent attorney Toshio Nakao and 1 other person
2 Figure Figure 3/-1'l scrap"I-f Figure 5

Claims (2)

[Claims] (1) Send an ultrasonic pulse beam into the living body at a constant repetition rate, receive the reflected wave, amplify this received signal, and receive the amplified received signal simultaneously on multiple channels. A parallel wave receiving circuit that performs wave phasing, an adder that adds the received signals of each channel of the parallel wave receiving circuit by alternately inverting the signs, and having a frequency that is an integer multiple of the transmission repetition frequency and that is complex to each other. a first complex signal converter that mixes a set of complex reference signals in a conjugate relationship and the received signal added in the adder to convert the received signal into a complex signal; and the complex signal a first autocorrelator that calculates an autocorrelation function of a complex signal by setting a delay time of a first speed calculator that calculates the amplified reception signal, and a set of complex reference signals having a frequency that is an integral multiple of the transmission repetition frequency and having a complex conjugate relationship with each other, and the amplified reception signal. a second complex signal converter that converts a wave signal into a complex signal; a second autocorrelator that calculates an autocorrelation relationship of the complex signal by providing a delay time for the complex signal; and the second autocorrelator. and a second velocity calculator that calculates the velocity in the traveling direction of the ultrasonic pulse beam of biological movement from the output of An ultrasonic diagnostic device characterized by: (2) Send an ultrasonic pulse beam into the living body at a constant repetition rate, receive the reflected wave, amplify this received signal, and receive the amplified received signal simultaneously on multiple channels. A parallel wave receiving circuit that performs wave phasing, an adder that adds the received signals of each channel of the parallel wave receiving circuit by alternately inverting the signs, and having a frequency that is an integer multiple of the transmission repetition frequency and that is complex to each other. a first complex signal converter that mixes a set of complex reference signals in a conjugate relationship and the received signal added in the adder to convert the received signal into a complex signal; and the complex signal an autocorrelator that calculates an autocorrelation function of a complex signal by setting a delay time of A first speed calculator mixes the amplified received signal with a set of complex reference signals having a frequency that is an integral multiple of the transmission repetition frequency and is in a complex conjugate relationship with each other, and generates a received signal. a second complex signal converter that converts the complex signal into a complex signal; a frequency analyzer that calculates the frequency spectrum of the complex signal by providing a delay time for the complex signal; and an ultrasonic pulse beam of biological movement from the output of the frequency analyzer. and a second velocity calculator for calculating the velocity in the traveling direction of the ultrasonic pulse beam, and measuring and displaying the velocity vector distribution in the traveling direction of the ultrasonic pulse beam and the direction perpendicular thereto. .