JPS6125536A - 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] [Industrial Application Field] The present invention relates to an ultrasonic diagnostic device, particularly an ultrasonic diagnostic device that measures and analyzes various information such as in-vivo morphological and dynamic conditions or intra-tissue conditions from received ultrasonic waves. This invention relates to an improved ultrasonic diagnostic device.

[Prior art 1] A method has been developed to analyze ultrasound waves received from within a living body in order to discover abnormal tissue within a living body and perform morphological analysis and qualitative analysis of the abnormal tissue. There is.

It is known that the reflected and scattered waves within the living body of ultrasound transmitted into the living body change in a characteristic manner depending on the frequency characteristics of the attenuation A5 scattering of the tissue, and this fact It has been recognized that it is advantageous to specifically determine the attenuation coefficient of ultrasonic waves in tissues in the living body using the method, and to use this as in-vivo information. Conventionally, this attenuation coefficient has been determined by storing the ultrasonic reception signal and analyzing it on a computer, but this has the drawback of requiring a great deal of time and effort, and it is difficult to accurately determine the attenuation coefficient within the body. Although it was not possible to capture this information as information in R, it was not possible to actually use it as valid information.

[Objective of the Invention] The present invention has been made in view of the above-mentioned conventional problems.The main purpose of the present invention is that when the average frequency and dispersion of the power spectrum of an ultrasonic reception signal are determined in real time, the difference between 1 and 11 M in the living body. By determining the attenuation coefficient within the tissue in real time, it is possible to accurately determine the morphology and properties of the tissue in the living body, making tissue diagnosis easier! The purpose of this invention is to provide an lli device.

[In order to achieve the purpose of the invention, the number of this invention exceeds 1? In ultra-8-wave diagnosis 117i 4, which transmits a single-wave pulse beam into the living body at a constant green return frequency and receives, amplifies, and displays the reflected wave, the complex reference signal of the - pair, which is in a complex relationship with each other, and the reception are received. a complex signal converter that converts the received high frequency signal into a complex signal by mixing it with a high frequency signal; an autocorrelator that calculates the autocorrelation of the complex signal by providing a delay time for the complex signal; It includes 9 average frequency droplets that calculate the average frequency from the phase of the autocorrelation function, and measures the average frequency or dispersion of power spectrum 1 to ram in real time by analyzing the power spectrum of the ultrasonic reception signal from within the body. It is characterized by

[Example] Preferred embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows a block circuit of an ultra-8 wave diagnostic apparatus according to a first example of the present invention.

The output of the crystal Jl generator 10, which generates a stable high frequency signal, is supplied to a frequency division synchronization circuit 12, and the frequency division synchronization circuit 12 outputs various output signals of fixed frequencies. Transmission repetition frequency signal 100 for beam transmission, complex reference signal 102.1 for complex transformation
04, Ultrasonic diagnosis [tli] includes a sweep synchronization signal 106 for displaying results and a clock signal 108 for synchronizing each part of the apparatus. In the embodiment J3, the complex reference signals 102 and 104 have a complex relationship with each other.

4-J the IQ phase difference of 90".

The transmission (M number 100) is supplied to the probe 18 via the drive circuit 14 and the transmission/reception switching circuit 16, excites the probe 18, and transmits an ultrasonic pulse beam into the subject 20.

The reflected echo from the subject 20 is converted into an electric wave by the probe 18, and is transmitted from the transmission/reception switching circuit 16 to the high frequency amplifier 2.
After being sent to 2 and subjected to the desired amplification effect, the -7j
The output]] is supplied to the display unit as a normal B mode or M'E mode display signal, and the other output t is processed as information on the morphology, properties, etc. of the cow body tissue. supplied to

The output signal for displaying the normal B7-code or M-code is output from the wave filter 24 and the same D-A amplifier 26.
, 28 to the CRT display 30, and lowers the surface of the CR7 display 30 by i'1 degree.

The ultrasonic pulse beam of the probe] 8 is mechanically or electrically angularly deflected. A scan controller 32 is provided to stop the scan at a corner, and the scan position η signal of the scan controller 32 is synchronized with the clock block 6108 and is supplied to the probe 18 to
Sweep synchronization signal 10 which is 1q from the frequency division synchronization circuit 12 at the time
6 and C are supplied to display position control 1, D, S, C, and 28.

The characteristic feature of the present invention is that if the average frequency or dispersion of the power spectrum 1-hum of the ultrasound received signal reflected from within the body is determined in real time, it is IF. The attenuation coefficient is determined in real time, and this means that the ultrasonic reception signal obtained from the living body is
As shown in the figure, this e (t
) by setting a constant short time interval G to the waveform. and,
The ultrasonic received signal can be analyzed by finding the average frequency and dispersion or attenuation coefficient of the power spectrum of the received signal within this G, then shifting G little by little, finding data within each G, and combining these. be exposed.

In order to obtain the average frequency and dispersion value of the power spectrum or the in-vivo attenuation coefficient in real time, a device is used that complex-transforms the received signal and calculates its autocorrelation function.

The configuration will be explained below.

Since the other output of the high frequency amplifier 22 is subjected to autocorrelation calculation, the received high frequency signal obtained from the high frequency amplifier 22 is first supplied to the complex signal converter 36 and converted into a complex signal.

However, in the embodiment, the complex signal converter 36 has a pair of mixers 38a, 38b including phase detectors, and in each mixer 38, the received high frequency signal is operated on the complex reference signal 102, 104, respectively. , the complex reference signals 102 and 104 are in the I*18!1 range with a phase difference of 90 degrees as described above, so that the mixer 38 can output a complex signal corresponding to the high frequency signal.

That is, each mixer 38 outputs a signal having a frequency of the sum and difference of the image frequencies of the received high-frequency signal inputted by mixed detection and the complex reference signal, and these two signals are supplied to low-pass filters 40a and 40b. Only the difference frequency components are extracted.

In the mixed detection function of the mixer 38, the complex reference signals 102 and 104 are continuous waves of a single frequency, but the received high frequency signal, which is the other input signal, is a pulse wave containing information in biological tissue. A large number of spectral components will appear in the output of 40. The complex conversion by this complex signal converter is explained in detail in Japanese Patent Application No. 57-7049, and the complex signal obtained by this converts the real part to
If the imaginary part is YO, then the complex expression % expression % (1) Next, the complex signal subjected to complex conversion is input to the normalizer 44, and the amplitude of the complex signal of the above equation (1) is converted by the normalizer 44 to [1 ”. The absolute value of ZO in equation (1) JXO゛→Y Ol is the absolute 11I operator 4
6, and if the real part and imaginary part are divided by the absolute value J Specifically, in-vivo information is included in the angle when X01YO is expressed by Sin and COS. Therefore, the complex signal obtained by the normalizer 44 is expressed as =X, 4-iY, (2).

The complex signal normalized as described above is then subjected to calculation processing by the autocorrelator 50, and the delay amount "to 1 - Zl
The autocorrelation of is required.

First, input signal Z1 is delayed for one period by delay lines 52a and 52b to obtain Z2.

This output Z2 is expressed by the following formula.

Z 2 ・=X 2 +iY 2
・ ・ ・ ・ ・ (3
) Then, assuming that 72 cars -X2- i Y2 , the correlation can be found by the following formula.

ZI Z2 family - (X+ +f Y+ ) (X2- i
Y2 )=X+ X2 +YI Y2 +i (X2
Yl −X+ Y2 )...(4) In order to obtain the correlation as described above, the autocorrelator 50
has four multipliers 54a, 54b, 56a.

56b, and adders/subtracters 58a and 58b are provided to perform the correlation calculation.

Also, if the output of the adder/subtractor 58a is taken as R, then R-X+X
2 +YI Y2 ・・・・・・(5〉 is obtained, and on the other hand, if we write the output of addition/subtraction 'a58b as 1, 1=X2X+ -Y+ Y2 ・・・(6
) is obtained, and the outputs of both adders and subtracters 58 are combined and expressed by the following equation.

S-R+i] ...(7)
Since this output 84 includes signal fluctuation components and noise components generated from the device, an average is obtained by an averaging circuit to remove these noise components, and this average is g=
It is expressed as p+iT, and complex correlation is calculated.

The averaging circuit adds outputs delayed by one cycle through delay lines 60a and 60b to input signals at the current time to adders 62a and 6.
2b, and add this output j again to the delay line 60.
If this addition is implemented using a digital circuit, for example, the average value can be obtained by outputting the Q bit on top of the addition output. As the number of additions increases, the output value increases successively and finally reaches saturation.
In the example, weighting circuits 64a and 64b are provided to attenuate the output and add it to the input.

In other words, if the attenuation period is α and 1y, then the signal α'' from the current time signal, for example, 10 cycles earlier, is attenuated and added to the current time signal, so the influence on the output is small, and the low-pass filter It is possible to perform an averaging function similar to that of a moving average circuit or a moving average circuit.Furthermore, by changing the number of repetitions of the smearing circuit 64, it is possible to change the degree of averaging.

In the above manner, the correlation of the complex signal is obtained from the autocorrelator 50, and the autocorrelation value is S=R+ + I (8)
It is indicated by.

As mentioned above, the autocorrelation value S obtained in the above manner is the basis for analyzing the power spectrum of the received signal within the fixed short time interval G in FIG. Real-time processing of power spectrum analysis becomes possible.

Next, the real part R and imaginary part of the self-phase 11EI value S obtained by the autocorrelator 50 are sent to an average frequency calculator 66 that falsifies the average frequency and a variance calculator 68 that calculates the variance value of the frequency by 1. is input.

In the average frequency calculator 66, the average frequency C is calculated, and in the pre-average frequency calculator 66, the average frequency r is calculated based on the phase angle of the autocorrelation function, which will be explained above.

The power spectrum of the envelope signal in G is expressed as P(f
'), then the autocorrelation function S(τ) [is expressed by the following relational expression.

5(r)=f P(f)e"" frdf...
...9) Differentiating this = j 2rcftp(f)e"""df...
(10) So, if you set -〇 here, you will hear a roar. Furthermore, if S(τ) is −〇, then 5(0)
=fp (f)df =j2πr ・ ・ ・ ・ ・ (11)
The child is found as the average frequency.

On the other hand, since the autocorrelation function S(τ) is a complex number, it can be expressed as follows.

S(τ)=A(τ)eJφ"...(12) However, A(r)=Fllll"-----(13).Also, from the properties of the autocorrelation function, the ratio of S(0) is It can be transformed as follows.

Therefore, from equations (11) and (15), P becomes and can be determined from the phase angle ψ(τ) of the autocorrelation function. However, the differential value φ(0) of the phase angle can be obtained using the approximate expression % Formula %) where τ φ(0)=O. Therefore, as shown in equation (14), φ(τ) can be found from the beans and ■, and from equation (17), φ(
0) is obtained, f' is given by...(18).

On the other hand, in the dispersion calculation unit 68, a dispersion value is obtained from k and d obtained by the autocorrelator 50, and this dispersion calculation will be explained below.

The second differential of the autocorrelation function (12) is expressed by the following equation.

5(0)=△(0)-A (0)(φ(0))'...
...(19) Also, the second differential of equation (9) is R(0)=(j2π)'ff' p(f)df×(j
2π)2r2 ...(20), while the variance value σ2 is generally f (f-4")'p(f)d" σ2- □ f p(f)df =F-(F )' ・・・・・・(21)
is defined as By substituting equations (19) and (20) into equation (21), approximately... (22) is obtained. This 1 represents the rate of change of S(τ) with respect to the power 5(0), and from this equation it can be understood that σ2 is proportional to the power fluctuation.

Here, since S(τ) has already been calculated by the normalized complex signal 71, the variance value σ2 can be calculated using h and T according to the following equation.

σ' ---(1-J R'-to Ding
2) 2π2τ2 ...<23) That is, in the distributed computing unit 68, the square p units 70a and 70b
The beans calculated by the autocorrelator 50 are squared and R
, T', and 2 and T2 are added by the adder 72 to become R242.

This is calculated by the variance value calculator 74 according to equation (23), and the variance value σ2 is calculated.

The average frequency and variance value σ2 calculated as above are the values within a certain region G of the ultrasonic reception signal, and this region G is moved little by little and 02 is calculated for each region one by one. . The waveform thus obtained is shown in FIG.

Next, in the embodiment 83, an attenuation coefficient calculator 76 is provided which calculates the bag reduction coefficient in living tissue, and the average frequency and variance (11i) of the power spectrum are calculated.

The damping coefficient is calculated by 2.

The attenuation coefficient can be calculated by dividing the differential value of the average frequency t/IP by the dispersion value r, but in this example, the time Q is maintained as shown in Fig. 3(a). Point A and point B are set, and J is determined by dividing the difference between the average frequency rA at point A and the average frequency rA at point B, which is 8, by the variance value σ2.

In other words, the average frequency +l'A-fs is regarded as the differential value of the average frequency factor mentioned above (with, Δf=FA-
When #B is used, the damping coefficient is expressed as υ 6 .

Therefore, in the attenuation coefficient calculator 76, first, the average frequency r8 corrected by the time Q by the delay line 78 is calculated.
is calculated and inputted to the attenuator 80, thereby calculating the difference Δ1 from fA that is already inputted to the attenuator 80. Next, the divider 82 inputs the dispersion value σ2, and the attenuation coefficient α is calculated by dividing the value Δf obtained by the attenuator 80. This attenuation coefficient α is averaged by an averaging circuit in the same way as the autocorrelator 50 described above, and is calculated by an average lit 5 fJ delay line 84, an adder 86, and a weighting angle circuit 88. Figure 4 shows the (
The average value α of the attenuation coefficients finally obtained becomes a stable signal as shown in FIG. 4(C), which becomes a signal indicating the attenuation coefficient in the living body.

The average frequency C and dispersion value σ2 of the power spectrum obtained in the above J: method or the in-vivo attenuation coefficient are converted into image signals and selectively switched and displayed on the screen of the CRT 30. For example, a color is determined in response to a change in the attenuation coefficient, and a change in the attenuation coefficient at each position within the body can be displayed as a change in color.

[Efficacy of invention! ! ! ] As explained above, according to the present invention, the average frequency and dispersion of the power spectrum are determined in real time using autocorrelation, and the attenuation coefficient is calculated as necessary, so that the in-vivo attenuation can be achieved. It is now possible to find the coefficients in real time,
This makes detailed morphological or qualitative analysis of the tissue at each position within the 9-piece structure extremely easy.

Therefore, in ultrasonic diagnosis, for example, it is possible to perform so-called tissue diagnosis to determine whether abnormal tissue is benign or malignant.
Further, it becomes easy to display images of the progress status of lesions and other useful information, and by combining them with B'E-mode or M-mode images, it is possible to contribute to various diagnoses.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing a preferred embodiment of the ultrasonic diagnostic I1Ii device according to the present invention. FIG. 2, FIG. 3, and FIG. 4 are explanatory diagrams of arithmetic processing of ultrasonic reception signals in each arithmetic unit in this embodiment. 10...Crystal oscillator 12...Divide period circuit 18...Probe 20...Object 30...CRI 36...Complex number 18 converters 38a, 38b...Miki 40 ... Low-pass filter 44 ... Normalizer 46 ... Absolute 1avi calculator 48a, 48b - ... Sapphire device 50 - Autocorrelator 52a, 52b ... Delay line 54a
, 54b , 56a , 56b
-) Trigram decoder 58a, 58b...Adder/subtractor 66...Average frequency calculator 68...Dispersion calculator 7Qa, 70b...Squaring unit 72...Adder 74...Dispersion value unit 76... Attenuation coefficient calculator 78... Delay line 80... Subtractor 82... Divider.

Claims (3)

[Claims] (1) In an ultrasonic diagnostic device that transmits an ultrasonic pulse beam into a living body at a constant repetition frequency and receives, amplifies, and displays the reflected waves, a set of complex reference signals and received high-frequency signals that have a complex relationship with each other are used. a complex signal converter that mixes and converts a received high frequency signal into a complex signal; an autocorrelator that calculates the autocorrelation of the complex signal by providing a delay time for the complex signal; and an autocorrelator that calculates the average frequency from the phase of the autocorrelation function. It includes an average frequency calculator that calculates the average frequency and a variance calculator that calculates the variance from the power fluctuation of the autocorrelation function, and analyzes the power spectrum of the ultrasonic reception signal from within the living body to calculate the average frequency or variance of the power spectrum. An ultrasonic diagnostic device that measures time. (2) In the apparatus according to claim (1), an attenuation coefficient calculator is provided to calculate an attenuation coefficient from the average frequency and the dispersion value, and the attenuation coefficient in the living body is measured in real time, and the attenuation coefficient changes. An ultrasonic diagnostic device characterized by displaying. (3) In the apparatus according to claims (1) and (2), a change in the average frequency, a change in dispersion, or a change in the attenuation coefficient of the ultrasonic received signal between the ultrasonic diagnostic image on B mode and the power spectrum. An ultrasonic diagnostic device characterized by displaying images simultaneously or separately using different colors.