JPS6036036A - Ultrasonic diagnostic apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to motion analysis and blood flow measurement of tissue in a specific part of a living body using an ultrasonic diagnostic apparatus.

(b) Background of the technology In recent years, ultrasonic diagnostic equipment has come to be widely used in medicine due to its non-invasive nature in living organisms, and its technology has also rapidly advanced. Ultrasonic diagnostic equipment can be broadly classified into diagnostic imaging equipment and blood flow measurement equipment. Diagnostic imaging equipment transmits ultrasound bursts with a beam having a predetermined directivity, receives ultrasound reflections from living organisms, and scans the beam. Mainly, the image is displayed on a cathode ray tube or the like in synchronization with this, but recently, beams have been scanned using multiple transducers, which are conversion elements that transmit and receive ultrasonic waves, by applying the principle of a phased array antenna. We have also developed techniques to do this. BACKGROUND ART Blood flow measurement devices have conventionally utilized the Doppler effect, and recently research and development has begun on two-dimensional or three-dimensional blood flow vector measurement using a plurality of transducers.

Based on the above-mentioned technical background, the present invention attempts to provide diagnostic information by correlating the signals received by a plurality of beams and displaying the movement inside the living body as a vector.0 (c) Prior art and problems As mentioned above, the Doppler effect has been the main method used to measure the movement inside a living body, but the following invention, which measures blood flow velocity based on the correlation of ultrasound reception signals, was filed by the same inventor as the present inventor. Since the present invention is a further improvement and development of the following invention, the following invention will be described below as prior art.

Patent application: 1)? Application date: 1970-170107: 1977
October 26, 2006 Name of invention: Ultrasonic pulse current meter Inventor: Shin Amemiya - The above invention as a prior art (Patent application 170107/1982)
The following is an explanation based on disaster cases.

FIG. 1 is an explanatory diagram of measuring a two-dimensional velocity vector of blood flow using two ultrasonic beams.

In the IT diagram, 41 is a transducer, and for the sake of explanation, it is assumed that it is equivalently composed of two transducers 41-1 and 41-2. 44-1 and 44-2? l!
It is assumed that the direction of one beam is shown and 44-1 and 44-2 are opened at a slight angle θ. It is assumed that each of the beams (hereinafter referred to as beams 44-1 and 44-2) has a directivity of the same solid angle ω. 44-11 and 44
-12 is a conical zone including the measurement targets of the beams 44-1 and 44-2, and the measurement target is blood flowing through the blood vessel 42-1. The conical zone will be referred to as the sample volume here. Sample volume 44-11
and 44-12 exist at a distance of 1 from the transducer 41 and with a distance width of h. The angle θ formed by the beam is sufficiently small, and therefore the zone 44
-11 and 44-12 are sufficiently close to each other, and the velocity of the blood flow flowing through the zone is constant. 0 It is mainly red blood cells that reflect ultrasonic waves in the blood, so the ultrasonic blood flow meter The object of measurement is red blood cells, but the red blood cells are not evenly dispersed in the blood, but form some clumps. Therefore, the reflected signal of the blood flow from the transducer 41-1 or 41-2 has an amplitude change sufficient to be a measurement target.
The correlation between the received signals obtained from 1-1 and 41-2 can be extracted, and from this correlation, the blood flow velocity component in the direction perpendicular to the beam can be determined.
shall be.

Conventional technology uses a device that incorporates phased array antenna technology to form two beams.
Isometrically, this is equivalent to forming two beams 44-1 and 44-2 by two transducers 41-1 and 41-2 in the IT diagram. Therefore, the received signal handled by the correlator is the received signal obtained by beams 44-1 and 44-2, and the received signal extracted from the sample volumes 44-11 and 44-12 mentioned above is the sample volume on which the correlation value is calculated. The extraction of the reception number 43 is determined by observing the part to be measured using a known ultrasonic imaging technique, and the measurement point is set, for example, at the measurement point 42 in Fig. 1.
〇 beams 44-1 and 44- The output signal of the sample bold circuit described above corresponding to No. 2 is input to the correlator.

Assuming that the TID beam 44 shown in 42-2 in FIG. 1(a)
If the blood clot at -1 moves as shown in beam 42-2 of beam 44-2 after time τd has elapsed, the correlator outputs a mutual phase open peak time difference detection voltage corresponding to τd. On the other hand, the distance traveled by the blood during the time τd is the first
As can be seen from Figure (a) <1. , = θ are known values and can therefore be easily determined. Therefore, by dividing the moving distance Ate by the τd, the blood velocity x can be determined. The above calculations are performed by the speed calculation circuit.

In the conventional technology, the velocity is detected only by the above-mentioned Vx based on the correlation of the received signal, and regarding the measurement point 42-3, it is the blood flow velocity component orthogonal to the beam 44-1. Therefore, the true blood flow velocity is two-dimensional. Beam 44-1 to find the vector
In the prior art, it is necessary to calculate the velocity component in the direction (denoted as Vy) by applying the known ultrasonic pulse Doppler blood flow measurement technique to the beam 44-1.

Since VX and vy have been determined in this way, they can be expressed in a two-dimensional blood flow velocity vector V1 as shown in FIG. 1(b) using a vector calculation circuit. Figure 1 (b
), V)r is determined by a Doppler blood flow meter, so it is set as vyd.

As described above, in the prior art, two-dimensional velocity vectors of blood flow are determined, but one vector Vx is determined from the correlation value of the received signal, and the other vector vy is determined by pulsed Doppler measurement. In conventional pulsed Doppler measurement, it is theoretically impossible to detect the velocity component (Vx) orthogonal to the ultrasound beam at the measurement point because the Doppler effect does not appear.
Although inventions that try to determine values using values are a major feature of the prior art, there are problems in that combining a correlation method and a Doppler method in one device requires a sloppy configuration and is expensive. ) Purpose of the Invention The present invention solves the problems of the prior art described above, and provides an apparatus that can also measure the velocity vy in the ultrasonic beam direction using a correlation method and measure a two-dimensional velocity vector using a correlation method. The device can be quickly purified and made inexpensive, and by passing it through a filter, it can quantitatively measure not only the °cm flow but also the movement inside the can body, such as the heart wall, as a vector, providing more advanced 1W information. Make it your goal to do so.

(e) Structure of the Invention The present invention uses at least two beams having the same directivity that are substantially parallel to each other and close to each other, simultaneously or mutually at θ1.
An ultrasonic burst with the same ultrasonic frequency is transmitted to the subject at the same repetition frequency of a rectangle, and the ultrasonic reflection from the subject due to the ultrasonic burst is received in correspondence with each of the two beams. In an ultrasonic transmitting/receiving device that outputs two received signals, each of the two received signals is sampled at the same predetermined sampling frequency for the same predetermined time length that can be set at a specific part of the subject. Correlation that calculates a two-dimensional cross-correlation function between the sample circuit output data corresponding to one of the 822 beams and the sample circuit output data corresponding to the other beam. Invention #1 and Invention #1, each having a display unit that displays the output of the correlator, and the invention #1 include providing an image filter on the input side of the display unit to cut the low frequency component of the input signal to the display unit. The invention consists of two inventions in which bypass filters are respectively provided on the two input sides of the above-mentioned phase IA device, and the above-mentioned object is achieved by the present invention.

(f) Embodiment of the Invention Figure 2 shows a 13'l relationship diagram between the beam of the ultrasonic transmitting and receiving device related to the present invention and the blood flow to be measured.
In a), 1 is a transducer 1 that transmits ultrasonic pulses to a subject and receives reflected ultrasonic waves that are brought into contact with the surface of the subject to form two beams.
-1 and 1-2 are shown separately. When the transducer is a phased array system using a counting transducer, the beam is formed by the phased array, so the C transducers 1-1 and 1-2 are effectively two transducers. 02 beams 2 as deuser
-1 and 2-2 each have an equal solid angle ω, and are directed toward the subject at a slight opening angle θ. The transducers 1-1 and 1-2 transmit and receive ultrasound pulses having the same repetition frequency and the same ultrasound frequency in the beam direction.

As mentioned above, blood forms clusters with a coarse and dense distribution of red blood cells, and these clusters are the object of blood flow measurement. 42-2 in FIG. @2-11 and 2-21, which show one of the nodules moving at , are the conical zones of beams 2-1 and 2-2, which occupy a section of 14 at a distance of 18 from transducer 1, and are also called sample volumes. However, here we will call it the zone. In the blood flow measurement according to the present invention, the part of the measurement target, for example, the blood vessel 42-1, is known by another ultrasonic imaging means, and the beam 2 is set so that the zones 2-11 and 2-21 cross the blood vessel 42-1 using the part information. -1 and 2-2 and zones 2-11 and 2-21 are set. This zone means extracting only the signals necessary for measurement from the received signal, and is electrically performed by applying a gate corresponding to the above-mentioned position 43 and section 14 to the received signal. The blood flow that flows through zone 2-11 and zone 2
-22, and during this period, the speed of blood flow and the shape and size of blood clots are constant. In other words, the above-mentioned conditions are almost satisfied for the blood flow to be measured by ultrasonic waves, in which the beam opening angle θ is small enough to be considered constant within the range where the two zones can be separated. Therefore, as shown in Figure 2(a), zone 2-11
After the formation time has elapsed, the blood clot 42-2 existing in zone 2-21 exists as 42-100, and if this time and displacement are known, the xy two-dimensional blood flow velocity Vxy can be calculated. I can do it.

The present invention attempts to determine the blood flow velocity vxy by calculating the correlation between two sets of received signals obtained in zones 2-11 and 2-21 and from the temporal change in the correlation.

Correlation is a statistical term that expresses the relationship between two sets of numbers.
The analog received signal of 2 is digitized at the same sampling frequency to spatially address the beam direction of each zone, and the time change of the signal of each address is determined by the repetition frequency of the ultrasonic pulse, and the sampling is performed as shown in Figure 3. Two address spaces consisting of a signal sequence t and a repetition frequency sequence n are formed corresponding to zones 2-11 and Th 2-21, and the two sets of zones A and B in the space are calculated according to the following formula to calculate the mutual correlation ( This is because the correlation between two sets of different data is called cross-correlation.

・・・・・・・・・ (1) In equation (1), C(m + τ): It is called the cross-correlation function and the zone A(n,
t)c! = shows the cross-correlation of data B (n, t).

n: Sampling address, which is divided into 640-addresses in this embodiment.Ot: Address of repetition frequency, which is divided into 32 column addresses in this embodiment.

m: shift value of n for correlation (-16°-
15,......,+15. +16) and specify the address of n.

τ: t shift value for correlation (-8°-7
, ......, 7. Input the value of 8) to specify the address of t.

The above-mentioned numerical value of net has been set in consideration of arithmetic processing capacity in consideration of cost performance and sufficient accuracy of the value of the correlation function.

The above-mentioned values of m and τ were set after considering the algorithm with the above-mentioned negativity.

The first term of equation (1) is data A(n) as shown in FIG.

t) is 3-L, zone B (n, t) is the row address 16-47. Data 3-2 surrounded by column addresses 8 to 23 is multiplied and added to data 3-1, so in the second term, data 3-1 is added to data 4B.
(n, t) and data 3-2 as data A(n, t)
By performing multiplication and addition as follows, the correlation of only the it term is eliminated and made fair. In other words, equation (1) shows an algorithm for determining a more accurate correlation (correction) from two finite sets of data. 11
An explanatory diagram focusing on 2-21 and 2-21 is shown in FIG.

This will be explained below.

(L) Dividing n into 640-addresses is the fourth
This means that section 14 in the figure is sampled 64 times. Therefore, one unit of n corresponds to a distance of 14/134 [glue]. One unit of t in equation (1) is the repetition period T [seconds] from the condition. ] corresponds to

Suppose that C(m2τ) has a maximum value at m and τ. The physical meaning of this is that the data stored at point Ap, which is zone 2-11, will be transferred to point Bp after mpT' (seconds). This means that they most likely converge.

Let the distance between zones 2-11 and 2-21 be L [glue] and Ap
Assume that a distance of <r (glue) is taken from the point in the beam direction as shown in FIG. 1, and the distance between APTBp is 4 (glue).

4 r=-・fp (glue) ・・・・・・・・・・・・・・・
(2) 4 1=(bi+ ,,I/, ・・・・・・・・・・・・・・
...(3) Substituting equation (2) into equation (3), A=lL'+(-・fp)")"...
...(4) Obtain 4. Therefore, the speed at which C(m, τ) reaches its maximum value■
xy is I Vxy = = llt + (”, fp)・Imaginary, =
(5) mpT mpT 64 ◎ In equation (5), 'r, l, and Al1 are known, so mp+τp is given and the two-dimensional blood flow velocity vXy can be found. Equation (5) is calculated by an arithmetic circuit. The calculated results can be displayed digitally, but the direction and approximate size of the blood flow can be visually observed by displaying them as vectors as shown in FIG. 5(b), which is effective for diagnosis.

In FIG. 5, the coordinates x+y that define the direction of blood flow are as shown in FIG. 5(a). Variable m of the cross-correlation function C(muτ).

Define τ as shown in (b). 0 or m is expressed by concentric circles, τ is expressed in the radial direction, and the solid line is positive and the dotted line is negative◎
Therefore, when the blood flow is as shown in (a) vxy, m
If p ” 2 *τP=3, it will be displayed as shown by the thick solid line in figure (b), and it will move from the center point to the intersection of m=2°τ=3 (arrow m p =2 *τp=3). The two-dimensional velocity vector Vxy is shown in FIG. The ultrasonic driving pulse is formed into the f transducer.
1 and L-2 transmit an ultrasonic burst to the subject.

The two transducers each receive ultrasonic waves reflected from the subject, convert them into electrical signals (hereinafter referred to as received signals), and output the signals, which are amplified by receiving amplifiers 3-1 and 3-2, respectively, and sent to a detection circuit. 4-1 and 4-2 detect the ultrasonic carrier frequency and send it to A/D converters 5-1 and 5-2.

A/D: ] Inverters 5-1 and 5-2 perform sampling as shown on the horizontal axis t in FIG. 3 to the gates forming zones 2-11 and 2-21 shown in FIG. ◎The gate signal is output from the master osso radar 11 in the delay circuit 12, which determines the measurement area using other means such as ultrasonic images and adjusts the timing of the gate. 〇The output of the delay circuit 12 is the pulse generator 13
Then, a pulse with a gate length that includes the measurement site is adjusted and created using the same method as described above, and the gate pulse is divided into 32 pulses according to the example from above to generate gated sampling pulses. do. The gated sampling pulses are sent to A/D converters 5-1 and 5-2.

The outputs of the A/D converters 5-1 and 5-2 are input to a two-dimensional cross-correlator 7, and the gate signal from the pulse generator 13 and the transmission timing signal from the mass phoresis relay 7711 are also input to the correlator 7. 1 shown in Figure 2(a)
3 and 14 are created. Details of the two-dimensional cross-correlator 7 will be described later, and the output of the correlator 7 is sent to the image processing unit 9.
The image processing section 9 performs processing for displaying the image shown in FIG. 5(b) described above. The output of the image processing section 9 is input to the display section 10 to display a two-dimensional velocity vector and digitally display the magnitude of the velocity.

FIG. 7 shows the details of the two-dimensional cross-correlator 7 in a systematic manner.

In FIG. 7, gated digital reception signals, which are the outputs of A/D converters 5-1 and 5-2 (7) shown in FIG. 6, are input to input terminals 7-1 and 7-2. The human power corresponding to the two beam zones 2-11 and 2-21 (FIG. 2(a)) is stored in the RAM (Random Access Memory) 7.
-3 and 7-4. In the above equation (1), RAM7-3 has A(n, t), RAM7-4
The data of B(n, t) is stored at the address shown in Figure 3.The data of ORAM 7-3 and 7-4 is stored in the ORAM 7-3 and 7-4 according to a program prepared in advance by the MPU (micro programming unit) according to instructions 7 and 8. It is read out under the control of the Nini Kasa address controller, inputted to the one-dimensional cross-correlator 7-5, and sent to the MPU.
In accordance with the command 7-8, the addition inside the first and second terms of equation (1) is performed and input to the signal processor 7-7.

The signal processor 7-7 memorizes the input and adds the outside of the first and second terms of equation 1) according to the instructions from the MPU 7-8, and further adds the first and second terms to obtain a two-dimensional cross-correlation. Perform the calculation.

The calculation result is displayed as a speed vxy on the display unit 10 via the image processing unit 9 using m and τ as variables, but as described in (5) above.
The value of vxy in the equation is also the transmission timing signal (input cuff -9),
The calculation is performed by the signal processor 7-7 by inputting the gate pulse (input cuff-1O) of the pulse generator and by setting a constant value of the beam opening angle ω. The calculated value is input to the cuff-1 by specifying data by observing the display unit 10 and feeding it back to the signal processor 7-7 via the image processing unit 9.
l) The vxyO value can be fixed and displayed digitally on the display unit 10. o7-11 is connected to the image processing unit 9 at the β power end of the two-dimensional mutual integration device 7.
The output * mark of PU7-8 indicates that the MPU output commands each part @ The explanation of the above-mentioned general assembly system diagram Figure 6 is based on the blocks 6-1, 6-2 indicated by the dashed-dotted line shown in Figure 6. 06-1 and 6-2 are bypass filters, and 8 is a lower frequency component than the signal. These image filters are used to narrow down the diagnostic target to blood flow. In other words, in the case of blood flow measurement, signals containing many low frequency components of blood vessel walls and heart walls become a nuisance, so they are removed. Therefore, the treatment of not including 6-1, 6-2, and 8 that has been described so far is rather when the movement of the blood vessel wall or heart wall is to be measured.In addition, 6-1,
6-2 and 8 are not all necessary for blood flow measurement, and it is generally sufficient to use 6-1 and 6-2 or 8.

In the above-mentioned embodiment of the present invention, an example is given and explained based on the prior art of Japanese Patent Application No. 56-170107, so the two beams used (Fig. 2(a) 2-1 and 2-2) )
implicitly presupposes the use of a phased array beam or two beams of such an array. However, the present invention is not necessarily attached to a phased array system, and the present invention is not necessarily attached to a phased array system, It is also possible to create a dedicated diagnostic device with two beams for the purpose of measuring 3-dimensional movement inside a living body and a 3-dimensional vector of blood flow velocity using the combination of the present invention with 3 beams. Of course, it is possible to create an ultrasonic diagnostic device with a temperature of 0 (g) °C.
Effects of the Invention According to the present invention, two beams of the array are used in an ultrasonic imaging device using a phased array, and two-dimensional movement inside the living body including the beams and blood flow velocity vector can be easily measured based on the principle of correlation. 6111 can be used not only for ultrasonic imaging but also as a diagnostic device, and by using two beams according to the present invention, it is possible to obtain a two-dimensional interlocking vector of movement and blood flow inside a living body by correlation, or by using three beams according to the present invention. Apply to the beam of 3
You can create a dedicated diagnostic device for dimensional velocity vector measurement0

[Brief explanation of drawings]

Fig. 3 shows an explanatory diagram using two ultrasonic beams according to the prior art, Fig. 2 shows an explanatory diagram using two ultrasonic beams according to an embodiment of the present invention, and Fig. 3 shows an explanatory diagram using two ultrasonic beams according to an embodiment of the present invention. FIG. 4 shows an explanatory diagram centered on the zones of two beams to explain equation (1) of the correlation function. FIGS. 5(a) and 5(b) show explanatory diagrams regarding the display of correlation values according to the embodiment of the present invention, FIG. indicates the internal system of the two-dimensional cross-correlator in the general system diagram 〇 The same reference numerals indicate the same objects throughout the diagram, 1, 1-1 and 1-2 are transducers, 2-1 and 2 -2 is two ultrasonic beams, 2-11 and 2-21 are zones, 5-1 and 5-2 are A/D converters, 7 is a two-dimensional mutual phase opener,
9 indicates an image processing section, 10 indicates a display section, 6-1 and 6-2
8 is a bypass filter, 8 is an image filter for cutting surrounding frequencies, 7-3 and 7-4 are RAMs, 7-5 is a one-dimensional cross-correlator, 7-7 is a signal processor, and 7-6 is a triple address controller. ,? −[−! Indicates MPU. Figure 1 Figure 2 Figure 6 Figure 3 Figure 4 Explanation ~7 a/234:? oJ/ Figure U (a) Figure

Claims (1)

[Claims] (1) Ultrasonic bursts of equal ultrasound frequency at a predetermined equal repetition frequency are transmitted simultaneously or alternately to the subject using at least two beams having equal directivity that are substantially parallel and close to each other. , an ultrasonic transmitter/receiver that receives ultrasonic waves reflected from the object by the ultrasonic burst in correspondence with each of the two beams and outputs two received signals; It has two sample circuit sections that respectively sample the two received signals with the same predetermined sampling frequency at the same predetermined time length that can be set according to a specific part, and corresponds to one of the two beams. (2) A correlator that calculates a two-dimensional cross-correlation function between the sample circuit output data corresponding to the sample circuit section and the sample circuit section output data corresponding to the other beam, and a display section that displays the correlator output. Ultrasonic bursts of equal ultrasonic frequencies are transmitted to the subject simultaneously or alternately at a predetermined equal repetition frequency using at least two parallel and adjacent beams having equal directivity, and The ultrasonic waves reflected from the specimen are received in correspondence with each of the two beams, two reception signals are output, and the ultrasound is transmitted over a predetermined period of time that can be set according to a specific part of the specimen. It has two sample circuit sections that sample the two received signals by -1 using the same sample frequency, and output data of the sample circuit section corresponding to one of the two beams and a sample corresponding to the other beam. It has a correlator that calculates a two-dimensional cross-correlation function with the circuit section output data, it has a display section that displays the output of the correlator, and it has an image filter that cuts low frequency components of the input signal of the display section. An ultrasonic diagnostic apparatus characterized in that a bypass filter is provided on the input side of the correlator, or a bypass filter is provided on the two input sides of the correlator.