JPH0679603B2 - 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. Further, for example, when a sector type probe is used in a conventional method to perform sector scanning to display a two-dimensional motion velocity, the motion of the fluid that flows uniformly from left to right as shown in FIG. On the left side of the figure, it is impossible to detect the frequency shift due to the Doppler effect on the left side of the figure, in the direction approaching the transducer in the traveling direction of the ultrasonic beam, on the right side of the figure in the direction away from the transducer. Therefore, 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 problems of the prior art, and makes it possible to measure and display the motion velocity component of the motion velocity of the moving part in the living body in the direction orthogonal to the traveling direction of ultrasonic waves. The purpose is to provide the technology to do so.

Means for Solving the Problems The present invention is directed to a parallel wave receiving circuit for simultaneously receiving and phasing a plurality of channels, an adder that alternately inverts and adds the sign of a received signal of each channel, and a frequency spectrum. The above-mentioned object is achieved by including a frequency analyzer for obtaining the above and a speed calculator.

Operation According to the present invention having the above 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 frequency analyzer. This means that the amount of change in the received signal between each channel caused by the movement of the moving part of the living body in the direction orthogonal to the traveling direction of the ultrasonic beam (channel direction) 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.

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 reference pulse signal and the received signal that are phase-shifted by 90 °, and 13 and 14 are the mixers 11 and 12 described above.
Is a low-pass filter (LPF) that filters the output of and outputs as a phase detection signal, 15 and 16 are A / D converters that convert the LPF phase detection signal to a digital signal, and 17 and 18 are the phases that are converted to digital signals. A canceller that removes the low-frequency component of the detection signal, 19 is a frequency analysis device that calculates the frequency spectrum of the received signal that has been phase-detected, and 20 is a frequency spectrum obtained by the frequency analysis device 19. It is a velocity calculation circuit that calculates a motion velocity component in a direction orthogonal to the traveling direction of the ultrasonic beam. 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, 2
Reference numeral 5 is a wave-reception phasing circuit, which phase-matches the wave-reception signal in order to display a B-mode image. 26 is a detector, 27 is an A / D converter, 2
8 is an image memory, 29 is a D / A converter, and 30 is a switching circuit.

The operation of the above arrangement will be described in detail 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 converted phase detection signals are complex phase detection signals having a 90 ° phase-shifted relationship with each other, that is, 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 which accompany body movements of tissues in the living body. The frequency spectrum of the complex phase detection signal from which the clutter components have been removed by the cancellers 17 and 18 input to the frequency analysis device 19 is calculated.
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), the relationship indicating that the sign of the received signal is inverted and added 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. 4 (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 of a moving part of the living body to be measured in a direction orthogonal to the traveling direction of the ultrasonic beam, and H (k) represents a complex conjugate of H (k), It is a function showing a sharp peak at k = 2π / p, pitch of p channel interval) as shown in FIG. 4 (b). On the other hand, since F (k) is a broad function, G (ω) represented by its product is a function showing a sharp peak. Also,
Here, the frequency spectrum is calculated by the complex phase detection signal at time intervals of the pulse repetition period T of n ultrasonic beams, and the number i is the number N of scanning lines for forming a B-mode image. , The pulse repetition period T of the ultrasonic beam and the frame rate F of the image are determined by the following relational expression iTNF = 1 (2). In the speed calculator 20, ωp, which gives the peak of the frequency spectrum, is calculated from this frequency spectrum, but due to the restriction of the equation (2), i can be made sufficiently large in order to give the ultrasonic diagnostic image real-time characteristics. However, since the frequency resolution becomes coarse, it is calculated as the frequency spectrum moment.

ωp = ω · | Gω | (3) From this ωp, the motion velocity component V in the direction orthogonal to the traveling direction of the ultrasonic beam of the moving part in the living body 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.

EFFECTS OF THE INVENTION As described above, the present invention is a parallel wave phasing circuit that simultaneously performs wave phasing on a plurality of channels, and an adder that adds the wave reception signals between the respective channels while inverting the signs alternately. By providing a circuit that converts the added received signal to a complex phase detection signal, a frequency analyzer that calculates the frequency spectrum, and a speed calculator that calculates the speed of the moving part in the living body from the frequency spectrum, It is possible to obtain the motion velocity component of the moving direction of the ultrasonic pulse beam of the moving part in the body, and in the conventional device, the state of the moving part in the living body that could not be measured and displayed was measured as vector information, It is possible to provide an ultrasonic diagnostic apparatus that can perform 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 details of another embodiment of the parallel wave receiving circuit in the first embodiment of the present invention, and FIG. 4 (a) is a diagram showing characteristics of an adder, FIG. (B) is a diagram showing the characteristics of the adder in the frequency domain, and FIG. 5 is a diagram for explaining the problems of the conventional ultrasonic diagnostic apparatus. 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 ……
LPF, 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 …… Reception wave phasing circuit, 26 ...... Detector, 27 …… A / D
Converter, 28 …… Image memory, 29 …… D / A converter, 30 ……
Switching circuit.

Front page continuation (72) Inventor Masaki Kawabuchi, 3-10-10 Higashisanda, Tama-ku, Kawasaki City, Kanagawa Matsushita Giken Co., Ltd. (56) Reference JP-A-61-100236 (JP, A) JP-A-60 -58131 (JP, A) JP-A-1-99537 (JP, A) JP-A-1-99538 (JP, A)

Claims (1)

[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 complex signal converter that converts the received signal into a complex signal, a frequency analyzer that calculates the frequency spectrum of the received signal converted into a complex signal, and a speed calculation that calculates the speed of the moving part in the living body from the frequency spectrum. An ultrasonic diagnostic apparatus comprising a measuring device and measuring and displaying a motion velocity distribution in a direction orthogonal to a traveling direction of an ultrasonic pulse beam of a moving part in a living body.