JPH0332654A - Ultrasonic diagnostic device - Google Patents

Abstract

PURPOSE:To exactly calculate and display the scattering coefficient of the organization by normalizing the respective scattering power from the organization of an object to be measured by using the respective scattering power of signals of different narrow bands from blood whose ultrasonic scattering characteristic is clear. CONSTITUTION:Ultrasonic pulses of plural narrow bands are transmitted simultaneously or separately. With regard to signals of plural narrow bands fetched by a band pass filter 10, a blood scattering power calculating means 6 calculates the scattering power of those which are from blood in a living body, respectively, and also, estimates blood scattering power in a position of the organization of an object to be measured from the calculated scattering power, respectively. Subsequently, by the blood scattering power estimated by the blood scattering power calculating means 6, a scattering coefficient calculating means 7 normalizes the organization scattering power calculated by an organization scattering power calculating means 5, and calculates scattering coefficients (b), (n) of the organization. In such a way, the scattering coefficient of the organization which is not influenced by an attenuation to the object to be measured can be calculated exactly and displayed.

Description

[Detailed Description of the Invention] [Summary] Regarding an ultrasonic diagnostic device that calculates and displays the scattering coefficient of a living body from received ultrasonic signals, the present invention relates to an ultrasonic diagnostic device that calculates and displays the scattering coefficient of a living body from received ultrasonic signals. The purpose is to normalize each scattered power from the tissue to be measured using the power, and to accurately calculate and display the scattering coefficient of the tissue to be measured. About a bandpass filter that extracts multiple narrowband signals from the reflected signals that are transmitted separately or by transmitting broadband ultrasonic pulses and reflected, and about the multiple narrowband signals extracted by this bandpass filter. , a blood scattering power calculation means for calculating the scattering power of blood in the living body, and further estimating the blood scattering power at the position of the a-texture of the object to be measured from the calculated scattering power, With respect to a plurality of narrow band signals, the m a scattering coefficient calculation means for normalizing the tissue scattering powers calculated by the tissue scattering power calculation means and calculating the tissue scattering coefficients b, n;
Place the bottom of the tank so that n is displayed.

[Industrial application field]

The present invention relates to an ultrasonic diagnostic apparatus that calculates and displays a scattering coefficient of a living body from received ultrasonic signals. In recent years, there has been an increasing demand for diagnostic methods using ultrasound to improve diagnostic accuracy through more quantitative and qualitative diagnosis. Attempts have been made to investigate the quality of the &ll weave from differences in acoustic properties, particularly attenuation characteristics and scattering characteristics, in mm as an expression of the quality of the &l weave. Here, the present invention relates to a method of quantitatively and accurately determining and displaying coefficients b and n when the scattering frequency characteristic is expressed as S (f) = bf among acoustic characteristics.

[Prior Art and Problems to be Solved by the Invention] Conventionally, when calculating the scattering coefficient of ultrasonic waves of a cut heart wall, the coefficient b is found for a normal heart wall and a heart wall at an infarcted site.
, n are known to be different.

However, when actually diagnosing using ultrasound from the body surface, the ultrasound is attenuated considerably before reaching the measurement site, and the degree of attenuation also differs for each individual, so it is difficult to accurately determine the scattering coefficient. The problem is that it is not possible. To solve this problem, a highly accurate measurement method for scattering coefficients that does not depend on attenuation is required.

The present invention normalizes each scattering power from mm of the object to be measured using the scattering powers of different narrowband signals from blood with distinct ultrasound scattering characteristics, and The purpose is to accurately calculate and display coefficients.

[Means to solve problems]

Refer to Figure 1! l! Explain the means to solve the problem.

In FIG. 1, a bandpass filter (group) 10 transmits multiple narrowband ultrasound pulses simultaneously or separately.
Alternatively, it is a filter that transmits a broadband ultrasonic pulse and extracts a plurality of narrowband signals from the reflected signals that arrive after being reflected.

The blood scattering power calculation means 6 includes a bandpass filter lO
For a plurality of narrow band signals extracted by the method, the scattered power from blood in the living body is calculated, and the blood scattered power at the position of the tissue to be measured is estimated.

The tissue scattering power calculating means 5 includes a bandpass filter lO
The later tissue scattering power from the &Ii tissue of the object to be measured in the living body is calculated for each of the plurality of narrowband signals extracted by the method.

The scattering coefficient calculating means 7 normalizes the tissue scattering power calculated by the tissue scattering power calculating means 5 using the blood scattering power estimated by the blood scattering power calculating means 6, and calculates the scattering coefficient bln of the tissue.

[Effect]

As shown in FIG. 1, the present invention transmits a plurality of narrowband ultrasonic pulses simultaneously or separately, or transmits a broadband ultrasonic pulse, and uses a bandpass method for anti-It B signals that arrive after being reflected. A plurality of narrowband signals are extracted by the filter (group) 10, and a blood scattering power calculation means 6 calculates the scattering power of the in-vivo blood for each of the plurality of narrowband signals extracted by the bandpass filter 10. From the calculated scattering power, the blood scattering power at the position of the tissue to be measured is further estimated, and the plurality of narrowband signals extracted by the Mii tissue scattering power calculation means 5 band-pass filter 10 are used to estimate the blood scattering power at the position of the tissue to be measured in the living body. Calculates the tissue scattering power of the target tissue, and normalizes the tissue scattering power calculated by the &l1ral1ra scattering power calculation by the blood scattering power estimated by the blood scattering power calculation means 6 by the scattering coefficient calculation means 7, Tissue scattering coefficient b, n
I am trying to calculate.

Therefore, the scattering power of each narrowband signal from blood with distinct ultrasound scattering characteristics is used to normalize the scattering power of each tissue of the measurement target, and the scattering coefficient of the tissue of the measurement target is calculated. By calculating and displaying, it becomes possible to accurately calculate and display the scattering coefficient of the ≪ structure, which is not affected by attenuation to the object to be measured.

〔Example〕

Next, the configuration and operation of one embodiment of the present invention will be explained in detail using FIGS. 1 to 8.

In FIG. 1, an ultrasound probe 1 transmits a plurality of narrowband ultrasound pulses simultaneously or separately in the direction of an ultrasound beam 1) in a living body, or transmits a broadband ultrasound pulse in the direction of an ultrasound beam 1) in a blood region A and It receives the reflected waves reflected from the group m8i area B and the like.

The transmitting circuit 3 generates ultrasonic pulses according to predetermined timing. This generated ultrasonic pulse is amplified by the transmission amplifier 2, drives the ultrasonic probe 1, and emits an ultrasonic pulse.

The reception amplifier 4 amplifies the signal received by the ultrasound probe 1.

The bandpass filter (group) 10 is a filter that extracts signals each having a predetermined narrowband frequency component from the received signal amplified by the receiving amplifier 4.

Mimim scattered power calculation means 55-1 to 5 m
The scattering power of m pieces of a predetermined narrow band signal of the ultrasound reflected from the tissue region B in the figure is calculated respectively.

Blood scattering power calculation means 6, 6-1 to 6-m0m
m scattering powers of a predetermined narrow band signal of the ultrasound reflected from the blood region A in the figure are calculated respectively, and the scattering powers of the set Wt region B of the object to be measured are calculated based on these calculated scattering powers. The m blood scattering powers at each position are estimated.

The scattering coefficient calculation means 7 uses the m blood scattering powers at the positions of the tissue of the measurement target estimated by the blood scattering power calculation means 6 to calculate the m &ll' calculated by the tissue scattering power calculation means 5. The scattering coefficients b and n are calculated accurately by normalizing the Ia scattered power and calculating the ratio (see FIG. 2).

The ultrasonic image generation unit 8 generates known B-mode images, M-mode images, and the like.

The display device 9 displays the scattering coefficients b and n according to this example calculated by the scattering coefficient calculation means 7, and the B mode image, M
This is a display that displays mode images, electrocardiograms, etc.

Tissue 12 is the tissue to be measured according to this embodiment. Tissue region B in this tissue 12 is the region for which scattering coefficients b and n are to be determined. Further, the blood region A is a region in which blood whose scattered power is known is flowing.

FIG. 2 shows a conceptual explanatory diagram of the present invention. This is a conceptual explanatory diagram when m=3, and three narrowband signals f, ,
The tissue scattering power and blood scattering power are determined for f, , f, respectively, and the scattering coefficients b and n are determined.

In FIG. 2(a), an ultrasonic beam 1) is emitted from an ultrasonic probe 1 as shown. Then, the scattered power from the blood region A where blood exists at the position of depth Zl is calculated for each of the narrow band signals f, , f2, and f, and from these calculated scattered powers, the blood at depth Z3 is calculated. Estimate the scattered power respectively. Further, the scattered power from the tissue region B at the depth Z3 is expressed as a narrow band signal f.

, fg, and fs.

Here, at the position of the depth Z2, there is a wall separating the blood and the m tissue as shown in the figure.Narrowband signals f, ft, f, The three scattered powers of and the blood narrowband signals fI, ft, , f of depth Zl
The calculation of the scattering coefficient bSn of the tissue at the position of depth Z3 using the three scattering powers of , will be explained using an equation.

The frequency characteristic of the transmitted ultrasound pulse is I(f), the scattered power spectrum from tissue is St (f+2), and the scattered power spectrum from blood is Ss (f).

Z), the characteristics including the transmission and reception characteristics of the ultrasonic probe and the sound field characteristics are F (f, z), and the attenuation characteristics of the round trip up to depth 2 are A
(f, z) represents the scattering properties of blood.

Assuming f4, the blood scattering power spectrum at the depth Zl is expressed as in the following equation (1).

S m (Lzl)=T(OF(f, zl) A(f,
zl) b m f' (1) From the scattered power spectrum of equation (1), the scattered power spectrum at depth Z3 is estimated as shown in the following equation.

S m (4, z3) = G (f, z3; zl) A s
(f, z2; zl) A (f, z3; z2) Sl (f
lzl)...(2) Here, G(flz3;zl) is a correction term for the sound field change between depth Zl and depth z3, that is, G(f, z3;zl) - F(4,z3)/F(f,z
l).

A m (f, z2; zl) is the attenuation characteristic of blood between depth Zl and depth z2 A t (f, z3; z2) if depth Z2 and depth z
The attenuation property of the tissue is between 3 and 3.

Further, the scattering power spectrum of the tissue at the depth Z3 can be expressed by the following equation (3).

S t (Lz3)=I(f) F(f, z3)^(f
, z3) b t f ” (31where, A(f, z3)=A(f, zl)A m (f, z2;
zl)^r (Lz3;z2)G(f, z3;zl)=
When equation (3) is normalized by equation (2) using the relationship F(f, z3)/F(f, zl), equation (4) below is obtained.

S (f, z3) = St (f, z3)/(S m (f
, z3) ・f −')=b d l b l −f
f1 ・ ・ ・ ・ ・ ・ ・ ・ (4) Here, equation (4) is expressed as below when equation (4), which expresses the scattering characteristics of the tissue when the blood scattering power spectrum is referenced, is expressed in decibels. Formula (5) is obtained.

101og+5S(f,z3)=10log+++(
by /ba )+to logf -n...
(5) Here, in the tissue scattering power spectrum in equation (3) and the blood scattering power spectrum at the position of the measurement target in equation (2), the bandpass filter lO is applied. The power of each signal is the second
The result will be as shown in Figure (b). Also, each frequency f
If the operation corresponding to equation (5) is performed at t1fz, fs, the result will be as shown in Figure 2 (c).Here, the scattered power of the three signals of the obtained frequencies f, , fg, f3 is Applying the least squares method to the ratio, as shown in Figure 2 (c),
Not only can n be determined from the slope, but also the scattering intensity b (=by/b) can be estimated from the intersection with the Y axis.

FIG. 3 shows an explanatory diagram of transmission ultrasonic pulse characteristics and band division side.

Figure 3 (A) shows how multiple narrowband ultrasonic pulses are transmitted separately and their respective reflected signals are extracted through a bandpass filter (BP filter) with characteristics indicated by dotted lines. Figure (b) collectively represents the frequency characteristics of the respective signals after passing through the band pass filter 10, which is indicated using the dotted line in Figure 3 (a).

Figure 3 (c) shows how a broadband ultrasonic pulse is transmitted and the reflected signal is passed through the bandpass filter 10 with the characteristics shown by the dotted line. This is a collective expression of the frequency characteristics of each signal.

FIG. 3(e) shows how a plurality of narrowband ultrasonic pulses are simultaneously transmitted and their respective reflected signals are extracted through a bandpass filter 10 having characteristics indicated by dotted lines.
FIG. 3(f) summarizes the frequency characteristics of the respective signals obtained at that time.

FIG. 4 shows an explanatory diagram of blood scattered waves.

FIG. 4(a) shows the scattered waves (received signal amplitude) from the parenchyma (&fl texture) and blood (blood cells) shown in FIG. 4(b) in association with each other. As is clear from this scattered wave, the power scattered from blood is considerably smaller than the power scattered from tissue. In addition, large reflections often return from the wall between &l1m and the blood. Therefore, the effects of multiple reflections occurring in &IIVa overlap with the blood reflected waves, making it difficult to accurately calculate the blood scattering power. Since this is difficult, Doppler detectors 6-2-1 to 6-2-m in FIG. 5, which will be described later, prevent these multiple reflections from being mixed into the scattered power from the blood.

FIG. 5 shows a configuration diagram of a specific example of the present invention.

In FIG. 5, the RF signal is input to bandpass filter(s) 10 and separated into a plurality of narrow band signals. High frequency components of these plurality of narrowband signals are blocked by an LPF, and further, f-'' characteristic filters 6-1-1 to 6-6 are used.
-1-m via Doppler detector 6-2-1 or 6-2
−m each manually. Here, the reason why the blood is passed through the f-TI characteristic filters 6-1-1 to 6-1-m is because the scattering characteristics of the blood are the frequency f, the scattering intensity (or the differential scattering cross section)
If b is, it is known that b,[4. Therefore, by passing the signal through a filter having f-4 characteristics, a signal having constant scattering characteristics with respect to frequency can be obtained. Note that n may be set to another value.

The Doppler detectors 6-2-1 to 6-2-m are composed of a quadrature detector, an MT filter, a blood flow velocity detection means, and a blood scattering power calculation means, and are used to calculate blood flow velocity and blood scattering power. It is.

6-3 detects a time period (time phase) in which the blood velocity or blood scattering power exceeds a threshold value (see FIG. 6).

6-4 compensates for variations in the scattered power from blood depending on blood flow velocity, or compensates for variations in blood scattered power due to variations in the volume fraction of red blood cells of the subject.

6-6 averages the scattered power from the blood for each narrow band signal within the time interval detected by the blood reference time interval detection means 6-3 or within the time interval specified by the external specification 65. It is something.

6-7 is the m-order interpolation of the scattered power from the blood at a time phase where the blood flow is very slow and the scattered power from the blood cannot be obtained sufficiently (Figure 6 (e) is the linear interpolation. ).

6-8 is for interpolating each narrowband signal when the depth is changed as shown in equation (2).

6-9 is for spatially averaging the power scattered from blood obtained between each scanning line.

5-1 is for &1) calculating the scattered power from the fabric.

5-2 is for spatially averaging the scattered power of &1)w1 obtained in each scanning line.

7-1 specifies a Rot or a marker as shown in the blood region A and tissue region B in FIG. 1, or operates a function that allows the Rot or marker to follow wall motion.

7-2 is for calculating the scattering coefficients b and n described above.

7-3 is for correcting the amount by which the scattering characteristics change depending on the angle between the myocardial direction and the ultrasonic wave, and 8-1 is information such as images and electrocardiograms from the ultrasonic diagnostic device.

9-1 performs display control.

9-2 is a display etc. for displaying information.

FIG. 6 shows an explanatory diagram of blood reference time intervals (time phases) and regions.

FIG. 6(A) shows the display area of the B-mode image, the areas where blood power can be calculated (Bl, B2), and the measurable areas of &II texture (TI, T2, T3).

FIG. 6(b) shows an electrocardiogram.

FIG. 6(C) shows both the blood scattering power and the time interval in which the blood power reaches a certain threshold level or more, with markers added to the display.

FIG. 6(d) shows blood flow velocity and a time interval in which the blood flow velocity reaches a certain threshold level or more with markers attached to display both.

FIG. 6(e) is a result of linear interpolation of frequency components with scattered power as shown by dotted lines. With this interpolation,
It becomes possible to obtain the scattering coefficient of the m-weave in all time phases.

FIG. 7 shows an example of displaying scattering coefficients.

FIG. 7(a) shows tissues T1, T
2 shows how the scattering coefficient of the tissue is calculated.

FIG. 7(b) is an electrocardiogram.

FIG. 7(c) shows an example of how the scattering coefficient n of the tissue Ti T2 changes over time.

FIG. 7(d) shows an example of how the scattering coefficients of tissues T1 and T2 change over time.

FIG. 7(e) shows blood reference time phase markers.

FIG. 7(f) shows an example in which the scattering coefficients are displayed in color on the M-mode image. Here, any combination of the scattering coefficients in FIGS. 7(a) to 7(e) is displayed on the display.

FIG. 8 shows an example of displaying scattering coefficients.

FIG. 8(A) shows an example in which the scattering coefficients b and n are displayed in color on the B-mode image displayed by color Doppler.
RoI representing the region is also displayed.

In this figure, color Doppler and scattering coefficients b, , n are displayed simultaneously, but they may be displayed on separate screens or only the scattering coefficients may be displayed.

FIG. 8(b) is for setting a marker in the myocardial direction with the B-mode image frozen, and correcting the angular dependence due to the angle formed with the scanning line direction. A correction coefficient is given, for example, as shown in FIG. 8(C).

FIG. 8 (2) is a profile display of spatial tissue scattering coefficients b and n with blood as a reference.

〔Effect of the invention〕

As explained above, according to the present invention, the respective scattered powers from the tissue of the measurement target are normalized using the respective scattered powers of different narrow band signals from blood with distinct ultrasound scattering characteristics, Since the configuration is adopted to calculate and display the scattering coefficient of the &I fabric of the object to be measured, it is possible to accurately calculate and display the scattering coefficient of Mm, which is not affected by attenuation up to the object to be measured. And this estimated &I
It is possible to display the accurate scattering coefficients b and n of the I-weave on the screen together with the B-mode image, electrocardiogram, etc., thereby improving diagnostic accuracy.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of one embodiment of the present invention, Fig. 2 is a conceptual explanatory diagram of the present invention, Fig. 3 is an explanatory diagram of transmitted ultrasonic pulse characteristics and band division side, and Fig. 4 is an explanation of blood scattered waves. 5 is a configuration diagram of a specific example of the present invention, and FIG. 6 is a blood reference time interval (time phase).
The explanatory diagrams of the parts, FIGS. 7 and 8, show examples of display of scattering coefficients. In the figure, l is an ultrasound probe, 5, S-t to 5-m are tissue scattering power calculation means, 6. 6-1 to 6-m are blood scattering power calculation means, 7 is a scattering coefficient calculation means, and 9 is a scattering coefficient calculation means. The display device, 1o, represents the bandpass filter(s).

Claims (3)

[Claims] (1) Calculate the scattering coefficient of the living body from the received ultrasound signal.
In the ultrasound diagnostic device that displays, multiple narrowband ultrasound pulses are transmitted simultaneously or separately, or broadband ultrasound pulses are transmitted and multiple narrowband signals are extracted from the reflected signals that arrive. A band-pass filter (10) and a plurality of narrow-band signals extracted by this band-pass filter (10) are used to calculate the scattering power of the in-vivo blood, and from the calculated scattering power, A blood scattering power calculating means (6) for estimating blood scattering power at a tissue position; and a blood scattering power calculation means (6) for estimating blood scattering power at a tissue position; The tissue scattering power calculated by the tissue scattering power calculating means (5) is calculated by the blood scattering power estimated by the tissue scattering power calculating means (5) and the blood scattering power calculating means (6), respectively, which calculates the scattering power. A scattering coefficient calculating means (7) for normalizing and calculating the scattering coefficients b and n of the tissue, and is configured to display the calculated scattering coefficients b and n of the tissue to be measured. Ultrasound diagnostic equipment. (2) In claim (1), the average scattering power of each narrow band signal is calculated for a time interval in which the blood scattering power or blood flow velocity exceeds a threshold level, and the calculated blood scattering power is An ultrasonic diagnostic apparatus characterized in that it is configured to calculate and display scattering coefficients b and n of a tissue to be measured using power. (3) Ultrasonic diagnosis according to claims (1) and (2), characterized in that the estimated scattering coefficients b and n of the tissue are displayed as a graph that changes over time. Device.