JPS6268441A - Ultrasonic tissue 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] [Technical Field of the Invention] The present invention relates to an ultrasonic zero tissue diagnosis device that transmits and receives ultrasound waves into a living body to obtain medical diagnostic information, and particularly relates to an ultrasonic zero tissue diagnostic device that transmits and receives ultrasound waves into a living body to obtain medical diagnostic information. The present invention relates to an ultrasonic tissue diagnostic device that diagnoses the tissue of a living body using nonlinear phenomena caused by interaction.

[Technical background of the invention]

As an ultrasonic tissue diagnostic device, it is possible to measure the in vivo m
One system performs a medical diagnosis of the biological tissue, and the other system performs a medical diagnosis of the biological tissue by measuring the product of the nonlinear parameter (B/A) of the biological tissue and the square of the reciprocal of the speed of sound. There is.

[Problems with background technology]

By the way, in a device that adopts the latter method, in order to obtain the absolute value of the nonlinear parameter (B/A), the ultrasonic sound field and the drive voltage used to excite the ultrasonic vibrator,
It is necessary to find the absolute relationship with the acoustic power of the ultrasonic waves transmitted from the ultrasonic transducer. For this reason, it is extremely difficult to obtain the absolute value of the nonlinear parameter (B/A), and it is desirable to improve diagnostic performance by characterizing living tissue using a simpler method.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and its purpose is to provide an ultrasound tissue that can characterize biological tissue using a simple method and improve medical diagnostic ability. The objective is to provide diagnostic equipment.

[Summary of the invention]

The outline of the present invention for achieving the above object is to provide an ultrasonic transducer array formed by arranging a plurality of ultrasonic transducers, and a plurality of ultrasonic transducers each adjacent to each other. A switching means for switching between ultrasonic wave transmission and wave reception, a drive voltage control section that can step-by-step change the drive voltage used to excite the transducer group for ultrasonic wave transmission, and a drive voltage control section that can vary the drive voltage in stages. A voltage-dependent parameter calculation circuit that calculates voltage-dependent parameters based on the reflected waves of the ultrasound transmitted each time, and a voltage-dependent parameter calculation circuit that calculates voltage-dependent parameters based on the reflected waves of the ultrasound transmitted each time, and A sound speed calculation circuit calculates the average sound speed of ultrasound in the ultrasound propagation path, and the calculated voltage dependent parameter and average sound speed are taken in, and the difference between adjacent ultrasound propagation paths is calculated to calculate the local voltage dependent parameter and the average sound speed. A local parameter calculation circuit that calculates local sound speed, local voltage-dependent parameters and local sound speed obtained from a phantom with known physical characteristics, and local voltage-dependent parameters and local sound speed obtained from a living body with unknown physical characteristics. The device is characterized in that it has a composite parameter calculation circuit that calculates a local composite parameter, and a display unit that displays a two-dimensional image based on the calculated local composite parameter and local sound speed.

[Embodiments of the invention]

The present invention will be specifically explained below.

First, the principle of the present invention will be explained.

First, we will explain the measurement principle of the complex parameter ξ (x + Explain the principle.

Measurement of complex parameter ξ (x, y)> Voltage-dependent parameter K (x, or nonlinear parameter (B/A) and sound velocity (
C) etc. is expressed as follows.

Here, k is a constant that depends on the attenuation 9 reflection 2 frequency of the ultrasound and the effect of the sound field. Therefore, the nonlinear parameter B
It becomes extremely difficult to determine the absolute value of /A.

Therefore, in the present invention, firstly, the attenuation of ultrasonic waves <A
A phantom (e.g., an agar graphite phantom) whose values are known, the scattering coefficient (γPM), the speed of sound (Co"), and the nonlinear parameter ((B/A)PM) is prepared, and an ultrasonic pulse is sent to this phantom. The voltage-dependent parameter KPH (
x + y) and sound velocity C''' (x + y). Figures 4 (a) and (b) show the measured K
PH(x, y) and C" (x+y) are schematically shown. The measured voltage dependent parameter K"'
(XI y) includes the effect of the constant in the previous equation (1).

Second, ultrasonic pulses are transmitted to the living body (subject) under the same conditions as the above phantom measurement, and the voltage dependent parameter K 1
10(x+y) and the speed of sound C''(x+y).

Figures 4(c) and (d) show the measured K''(
x, y) and Cl10(x, y). At this time, the attenuation 9 reflections of the ultrasound waves in the living body are unknown.

Thirdly, K''(x,y) obtained in the above measurement.

C'')l(x+y), K''(x,y), C
Bo (x, y) is used to cancel the influence of one frequency of the ultrasound sound field, and the attenuation, scattering, and
The complex parameter ξ(
x, y).

...(2) FIG. 4(e) schematically shows ξ(x, y).

The composite parameter ξ(x,y) obtained in this way
is a quantity that characterizes biological tissue. because,
This is because the composite parameter ξ(x, y) is the product of ultrasound attenuation, scattering coefficient, and nonlinear parameters in the living body, and each of these factors characterizes the living tissue.

Scanning of Ultrasonic Propagation Path> As shown in FIG.
From the first group of transducers centered on
Ultrasonic pulses are emitted in the direction where the ultrasonic deflection angle θ=0°). Then, the ultrasonic pulse travels straight through the transmission path AI pH in the living body, and the reflected wave at point P passes through the delivery path p.
The wave passes through HB+1 and is received by the second group of oscillators centered around B. Then, as will be described later, once the average sound velocity (11) and the total voltage dependent parameter (K l +) in this ultrasonic propagation path A+ P++ B++ are calculated, from the first oscillator centered on A1 again Ultrasonic waves are transmitted in the same way as above, and the point P1 of the transmitted ultrasound waves is
The reflected wave at □ is now received by the second group of vibrators centered around B12. And this ultrasonic propagation path AI
PI3 The average sound velocity (Kon2) at B + □ and the total voltage dependent parameters (K, □) are calculated. By scanning the ultrasonic transmitting position and receiving position in the same way, finally 2mXn pieces are calculated. A combination of average sound speed (K) and total voltage dependent parameter (K) is calculated.

<Measurement of average sound velocity (C)> If the ultrasonic propagation time t from ultrasonic wave transmission to ultrasonic reception is measured for each of the above ultrasonic propagation paths, the first transducer group for transmission and the one for reception can be measured. Since the center-to-center distance y with respect to the second transducer group is known, the average sound velocity can be calculated using the following equation.

However, since the speed of sound is unknown, θ is strictly unknown, and since there is no reflector at point P inside the living body, various techniques are actually used to find the speed of sound from equation (3). It becomes necessary.

Measurement of total voltage dependent parameter (K)> Using a linear electronic scanning probe l, emit an ultrasonic pulse toward the living body from the first group of transducers on the ultrasonic transmitting/receiving surface 2 in the same manner as in the case of sound velocity measurement. Then, the ultrasonic waves reflected at a specific point in the living tissue are received by a second group of transducers. At this time, the driving voltage U used for excitation of the ultrasonic wave is set to, for example, u=10.20.・
0. .

Find and memorize the received wave amplitude V [volts] when changing the voltage to 100 [volts].

Next, the slope γ and the intercept δ are determined by plotting the following equation (4) (FIG. 6).

1/vz=T/u2+δ ・(4) At this time, the following equation (5) is established between the drive voltage dependent parameter (K=δ/T), the nonlinear parameter (B/A), and the speed of sound (C). To establish.

K=Ko (1+B)/2A)/C"...(5
) where Ko is a frequency-dependent constant.

In this way, 2 m × n driving voltage dependent parameters (K) are determined.

<Measurement of local sound speed 9 local voltage-dependent parameters> From the zmxn total voltage-dependent parameters (K) and average sound speed (C) obtained as above, the local voltage parameter K (i, j) and local sound speed are determined, respectively. C(i,j) is determined by the following equation.

K(i,j) =K(i,j+1) K(i,j
)...(6)C(i+j) =C(i
, i+1) -C(i+j) 0.・(7
) The above is the principle of the present invention. Next, an embodiment of the present invention based on the above principle will be described.

<Sound Velocity Measurement> The block diagram in FIG. 1 shows the configuration of this embodiment. The transducer array 11 is the ultrasonic wave transmitting/receiving surface 2 of the probe shown in FIG.
When a voltage pulse is applied, an ultrasonic pulse is emitted, and when an ultrasonic wave is incident, a voltage is generated and the ultrasonic wave is detected.

The transducer array 11 (TI-T1211) has a transducer element width a of 0.45 m and an element center spacing d = 0.
．． It has 5 fins and 128 elements arranged in a straight line. Electric signals are sent and received to and from each of these transducer elements through lead wires 12 within the cable 3.

A CPU (central processing unit) 21 has a pulse generator that generates, for example, a 101 Hz reference clock, and divides the frequency of the reference clock to generate, for example, a 4 kHz rate pulse to drive 16 pulsers 14.

The output of the pulser 14 is connected to the transducer groups T, -T+6, centering on A, of the transducer array 11 by the multiplexer 13, which is a switching means.

The transducer array 11 contacts the body surface through the coating material of the probe, and the ultrasonic waves generated from the transducer elements are radiated into the living body. The speed of sound in standard living tissue is Co = 1530
m/S, then the ultrasonic beam is θ. For radiation in the direction, the delay time τ between each adjacent element is required. is To = (d/Co) ・sin θ
-(81), and the transmission delay circuit 15 is set so that each element is driven with such a delay time difference.

That is, PD+=O, po2=τo, PD3=2τ0°..., PD+b=16τ. give a delay time of

If the sound speed of the living tissue is 00, the ultrasound beam is θ.

A value C that is different from C0, but is generally not limited to C0.
It is. At this time, the propagation direction θ of the ultrasonic wave is sin θ/C=sin θo/Co from Snell's law.
The value is −f91.

After emitting the ultrasonic pulse, the multiplexer 13
A reception delay circuit 16 is connected to 16 transducer groups T, -T, , 6 centered on T.

The ultrasonic reflected wave signals received at ~T□, 16 are subjected to the same delay as in the case of transmission, are combined, and then input to the receiving circuit 19. That is, the delay time of the reception delay circuit 16 is RD
+=15τ. ,RD,=14τ. .

......, RD+s=τ. , RD +b=O
It is set as follows. In this way, the transducer group T, ~
T m * 1 is θ if the sound speed in the living body is C3 (C)
. It has directivity in the (θ) direction, and θ. Receive reflected waves from the (θ) direction.

The received signal is amplified and detected by a receiving circuit 19, A/D converted by an A/D converter 20, and stored in a buffer memory 22. The address of the buffer memory 22 is determined by a 10 MHz clock based on the timing of the rate pulse, and the address of the sample value of the received waveform stored in the buffer memory 22 has an accuracy of 100 ns from the time when the ultrasonic pulse is emitted. matches exactly.

The peak value of the stored waveform indicates the reflected wave from point P in the living body, and the propagation time t11 can be determined by detecting the time (address) of the peak value with the sound velocity calculation circuit 24. (9) mentioned above
Substituting the equation into equation (3), the sound speed C in the living body becomes: Since yz+co+θ0 is known, the sound speed calculation circuit 2 uses the propagation time t obtained by measurement.
4, perform the calculation of 00)2 to calculate the value of the sound speed C.

This calculated value is written into the frame memory 25.

FIG. 2 is a time chart 1 showing a method of measuring the ultrasonic propagation time t, and the rise t of the rate pulse.

The ultrasonic pulse is emitted at a slightly later time, and the peak time of the pulse is t. If there is a non-reflector at the intersection of the center of the transmitting beam and the center of the receiving directivity, a reflected wave having a peak at time t2 is obtained, and t is determined as the time interval between t2 and t.

<Measurement of voltage-dependent parameter (K)> The method of measuring the drive voltage-dependent parameter (K) is basically the same as in the case of sound velocity measurement, but differs in the following points.

The drive voltage control unit 17 operates under the control of the CPU 21,
The output voltage (driving voltage) U of the pulser 14 is 10.20.・
..., 100 (V). Each voltage (u
), a predetermined group of transducers is excited and ultrasonic waves are transmitted. The reflected waves of the ultrasonic waves transmitted for each voltage (u) are received by a predetermined group of transducers, and the amplitude (V) of the received signal is written in the buffer memory 22 for each voltage (u). . When ultrasonic wave transmission/reception is performed multiple times under the same conditions, the adding circuit 10 operates to perform averaging processing of the received signals.

Next, u written in the buffer memory 22,
v information (!!! received signal for each dynamic voltage (u)) is CPT
It is read out under the control of J21 and transmitted to the voltage dependent parameter calculation circuit 23. Then, in this voltage dependent parameter circuit 23, the slope γ and the intercept δ of the equation (4) are determined, and finally the average voltage dependent parameter (K) is written into the frame memory 25.

Measurement of Local Sound Velocity 1 Local Voltage Dependent Parameter> The 2m×n average sound velocity (C) and total voltage dependent parameter (K) written in the frame memory 25 in this way are CP
It is read out under the control of U21 and input to the local parameter calculation circuit 27. Then, in this local parameter calculation circuit 27, the calculations of equations 61 and 71 are executed,
The local sound velocity C(i, j) and the local voltage dependent parameter K(i, j) are determined.

Here, if the obtained local sound velocity and local voltage dependent parameters are obtained from the results of transmitting and receiving ultrasonic waves toward the phantom, then C'' (x, y) and KPH (x, y ), or CBo (x+y) and K'' (x+
y) is written into the frame memory 25 as

<Measurement of complex parameters> C”(x+y) written in the frame memory 25.

K"' (x+y) and C"(x,y), K1
10(x,y) is read out under the control of the CPU 21 and input to the composite parameter calculation circuit 28. Then, the computation of equation (2) is executed in the composite parameter calculation circuit 28, and the composite parameter ξ(x+y) is obtained. The obtained composite parameter ξ(x, y) is input to the D/A converter 29 via the display memory 26,
After being converted into an analog signal, it is manually input to a CRT display 30 serving as a display means.

<Display> FIG. 3 shows an example of the display on the CRT display 30, in which 31 shows an ultrasound B-mode image (tomographic image) of a living body;
32 is a local sound speed value image based on local sound speed C(i, j);
33 is a composite parameter image based on the composite parameter ξ(x,y), and 34 is a received signal pattern (A mode) as shown in FIG.

Reference numeral 36 denotes an ultrasonic propagation path, which is displayed superimposed on the ultrasonic B-mode image 31 as necessary. The local sound speed value image 32 is displayed in blue, for example, and its brightness is displayed depending on the magnitude of the sound speed value. Further, the composite parameter image 33 is displayed in red, for example, and its brightness is displayed depending on the magnitude of the composite parameter value.

The ultrasonic B-mode image 31 can be constructed by, for example, ultrasonic linear scanning or sector scanning, and in this case, the ultrasonic probe provided in the apparatus of this embodiment can be used in common. If the ultrasonic B-mode image 31 is displayed together in this way, the desired region 38 in the living body and the local sound velocity value image 32. The correspondence with the composite parameter image 33 becomes clear. Further, as shown at 39 in the figure, the sound velocity value and composite parameter value at the cursor point set in the image are displayed numerically at the position shown at 35 on the screen.

In this way, in the device of this embodiment, the composite parameter (ξ(x, y)) of the sound velocity (C) in living tissue, ultrasonic attenuation, scattering, and nonlinear parameters is transmitted to the patient (living body) in no way. It can be measured non-invasively and in a short time without imposing any burden. Moreover, this measurement can be carried out extremely easily by using a phantom whose ultrasonic attenuation (At''), scattering coefficient (γP''), and nonlinear parameter ((B/A)P'4) are known. . In addition, since both the measured sound velocity (C) and the composite parameter (ξ(x,y)) are displayed as two-dimensional images on the display screen, doctors and others observing the display screen can see the lesion area. It is possible to accurately and easily differentiate between the normal part and the normal part.

Furthermore, this ultrasonic tissue diagnostic device can be used simultaneously with a real-time tomography device that has conventionally been used for routine clinical examinations, and the same probe can be used for the examination, so while observing normal tomographic images, An ideal inspection method can be implemented in which one-touch switching to sound velocity and nonlinear parameter measurement mode at an appropriate cross section is possible.

Although one embodiment of the present invention has been described above, it goes without saying that the present invention is not limited to the above-mentioned embodiment, and can be modified as appropriate within the scope of the gist of the present invention. For example, the deflection angle during wave transmission may be set to a value other than 00.

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to provide an ultrasonic medical diagnosis device that can characterize biological tissue using a simple method and improve medical diagnostic ability.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an ultrasonic tissue diagnosis device that is an embodiment of the present invention, Fig. 2 is a time chart showing a method for measuring ultrasonic propagation time, and Fig. 3 is an example of a display in the device of this embodiment. Explanatory diagram, FIG. 4(a). (b), (c), (d), (e) to 6th
The drawings are for detailed explanation of the present invention, and are shown in FIGS. 4(a), (b), (c), and (d). (e) is a schematic diagram of the parameter image, Figure 5 is an explanatory diagram of the scanning method of the ultrasound propagation path, and Figure 6 is 1/u2 and 1/
It is a relationship diagram with v2. DESCRIPTION OF SYMBOLS 11... Ultrasonic transducer array, 13... Switching means (multiplexer), 17... Drive voltage control unit, 23... Voltage dependent parameter calculation circuit, 24... Sound velocity calculation circuit, 27... - Local parameter calculation circuit, 28... Complex parameter calculation circuit, 30... Display means (CRT display), T...
Ultrasonic transducer. Agent Patent Attorney Nori Ken Chika Yudo Dai Ko Noritake Mistake 2 Figure 8

Claims (2)

[Claims] (1) An ultrasonic transducer array formed by arranging a plurality of ultrasonic transducers, and a plurality of ultrasonic transducer arrays each having a plurality of adjacent ultrasonic transducers for ultrasonic transmission and reception. a switching means for switching, a drive voltage control unit that can stepwise vary the drive voltage used to excite the transducer group for ultrasonic wave transmission, and a drive voltage control unit that can step-by-step change the drive voltage used to excite the transducer group for ultrasonic wave transmission; A voltage-dependent parameter calculation circuit that calculates voltage-dependent parameters based on waves, and an average sound velocity of ultrasound in each ultrasound propagation path each time the center position of each transducer group for ultrasound transmission and reception is switched. A sound velocity calculation circuit that calculates
a local parameter calculation circuit that calculates a local voltage-dependent parameter and a local sound velocity by taking the difference between adjacent ultrasound propagation paths; a local voltage-dependent parameter and a local sound velocity obtained from a phantom having known physical characteristics; A composite parameter calculation circuit that calculates local composite parameters based on local voltage-dependent parameters and local sound speeds obtained from a living body with unknown physical characteristics, and a two-dimensional image display based on the calculated local composite parameters and local sound speeds. What is claimed is: 1. An ultrasonic tissue diagnostic apparatus comprising: a display means for performing a diagnostic operation. (2) The ultrasonic tissue diagnostic apparatus according to claim 1, wherein the local composite parameter calculated by the composite parameter calculation circuit is a product of attenuation, reflection, and nonlinear parameters of ultrasound.