JPH0324868B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ultrasonic diagnostic apparatus, and particularly to an ultrasonic diagnostic apparatus that transmits and receives ultrasonic waves of different frequencies into a living body and accurately displays a tomographic image thereof.

[Prior Art] Ultrasonic diagnostic equipment that transmits and receives ultrasound waves to and from a subject and displays tomographic images inside the subject is well known, and has been gaining popularity in recent years because it can be performed using a simple and harmless testing method. It is widely used for various diagnoses.

FIG. 5 shows a schematic configuration of a conventional ultrasonic diagnostic apparatus, in which ultrasonic waves are transmitted from a probe 10 toward a subject 12, and echoes reflected from within the subject 12 are detected. The signal is supplied to a transceiver 14 via a probe 10 . The output of the transceiver 14 is then supplied to the device under test 18 via an amplifier 16 with a predetermined amplification factor, and the detector 18 extracts only necessary signal components. The output of the detector 18 is input to a DSC (digital scan converter) 20, where it is processed for image display, and then an M mode or B mode image is displayed on a display 22.

In particular, the B-mode display displays a tomographic image inside the subject, and can provide extremely effective information for diagnosis because it can display the morphology of the actual organ at a desired site.

[Problems to be Solved by the Invention] Ultrasonic diagnostic equipment that displays such tomographic images can observe the shape of organs within a subject and a certain degree of internal state; There was a problem that it was difficult to quantitatively display the amount.

For this reason, it has not yet been possible to display on images all the accurate information needed to know the hardness and properties of organs or substances present within them, such as tumors, and There is a demand for an ultrasonic diagnostic apparatus that displays information that can be easily identified as is.

Conventionally, such quantitative information has been partially displayed in images, for example by examining the attenuation that ultrasonic waves receive when propagating through materials.
We try to obtain accurate information within the subject.

In general, the higher the density or mass of the tissue, or the higher the frequency of the ultrasound, the greater the attenuation of the ultrasound that passes through the body, and the attenuation is determined by how much attenuation occurs per unit frequency. The amount, that is, the frequency attenuation constant (hereinafter referred to as FDA) changes depending on the substance and the ultrasound frequency. Therefore, conventionally, the FDA of a given substance is estimated from the frequency distribution of the received signal obtained by an ultrasound diagnostic device.
Efforts are being made to find and quantify the FDA of the necessary limited area.

However, only a limited area of interest
FDA numerical display has some meaning as supplementary information when performing image diagnosis from tomographic images, but
Diagnosis based on this numerical value is rarely used in ultrasound diagnosis, which has a role as an initial diagnosis. In addition, this numerical display can only be obtained for each limited area, and there is a problem in that it is difficult to obtain quantitative information over a wide area over the entire area.

Therefore, instead of displaying FDA numerical values for a part of the inside of the subject, there is a demand for accurate image display of the inside of the subject as it is with quantitative display.

Purpose of the Invention The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to provide an ultrasonic diagnostic device that estimates FDA in all diagnostic areas in real time and displays this FDA information as an image. It is in.

[Means and effects for solving the problems] In order to achieve the above object, the present invention provides a transceiver that transmits and receives a plurality of ultrasonic waves of different frequencies, and a system that uses predetermined two ultrasonic waves. a difference calculator for orthogonally detecting the received signal and calculating an intensity difference; and a differentiator for differentiating the output of the difference calculator by the reciprocating path length of the ultrasonic wave; A feature is that the frequency-dependent attenuation constant is displayed as an image in all scanning regions.

That is, for different frequencies f ₀ and f ₁ , the frequency
Let A ₀ (r) be the received signal obtained by ultrasound at f ₀ and A ₁ (r) be the received signal obtained by ultrasound at frequency f ₁ , then FDA from distance r ₀ to r ₁ can be defined as follows.

D(r,f)={Ao(r1)−A1(r1)}−{
Ao (ro) − A1 (ro)} / (f1 − fo) {Ao (ro) − A1 (ro
)}...(1) Expression (1) can be expressed as shown in Figure 2, where the received signals A ₀ (r) and A ₁ (r) at the distance r ₀
100, the received signal A ₀ (r) at a distance r ₁
If the difference between and A ₁ (r) is 200, then FDA is 200−
100/(f ₁ − f ₀ )100. Therefore, the difference 100 and the difference
When 200 are equal, there is no attenuation, and the difference is
The larger the value of 200 is relative to the difference of 100, the greater the amount of attenuation.

And if A ₀ (r)−A ₁ (r) is B(r), then
The above equation (1) can be replaced as shown in the following equation.

D(r, f)=B(r1)-B(ro)/(f1-fo)・B(ro)
=r1−ro/(f1−fo)・B(ro)・B(r1)−B(ro)
/r1−ro=Δr/(f1−fo)・B(ro)・dB(r)/dr
...(2) As is clear from equation (2) above, the first term is a constant value including the initial value, and the second term is a differential value, so FDA can be estimated by finding this differential value. .

Since this differential value can be continuously calculated from the received signals of two frequency ultrasound waves,
It becomes possible to easily display tomographic images by FDA in real time.

[Embodiments] Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 1 shows the circuit configuration of an ultrasonic diagnostic device from emitting ultrasonic waves into the subject to performing FDA calculations. In the present invention, FDA calculations are performed using two received signals. Therefore, no matter which method is used, the transmitted and received ultrasonic waves must consist of multiple frequencies.

Therefore, the transceiver 24 oscillates two frequency signals, which are transmitted to the probe 10 via the signal switch 26.
is supplied to. Among conventional diagnostic devices, there is a multi-frequency tomographic image forming device that transmits and receives ultrasonic waves of a plurality of frequencies, and is described in detail in, for example, Japanese Patent Application No. 58-245396.

The two received signals obtained by the transceiver 24 are then supplied to quadrature detectors 28a and 28b,
Here, it is demodulated by the reference wave signal, and the quadrature detector 28a applies a signal of frequency _f0 , and the quadrature detector 28b applies a signal of frequency _f1 .
Therefore, two ultrasonic reception signals obtained by the transceiver 24 are respectively extracted.

For example, as shown in FIG.
Assuming that the received signal supplied from 4 has the spectrum shown in Figure a, when it is demodulated by the reference wave frequencies f ₀ and f ₁ , the spectrum will be as shown in Figure b for frequency f ₀ and Figure c for frequency f ₁ . The zero frequency signal component (DC component) shown in is extracted.

Therefore, the two received signals output from the orthogonal detectors 28a and 28b become signals containing information obtained from ultrasound waves of different frequencies. Then, this received signal is orthogonally detected using two reference signals having a phase difference of 90 degrees.

The two output signals from this quadrature detector 28 are:
The signal is converted into a digital signal by two A/D converters 30 and 31, and then supplied to an absolute value calculator 32 consisting of a ROM. This absolute value calculator 32 calculates an absolute value from the two signals, and this absolute value signal is supplied to a moving average circuit 34 to obtain the average value of the received signals for obtaining object information.

In order to perform such arithmetic processing in real time, the speed of the A/D converters 30 and 31 is set to about 20 MHz, and in this case, the moving average circuit 34
It is sufficient if the average time is about 2μs.

The average values of the received signals from the ultrasonic waves of frequencies f ₀ and f ₁ obtained as described above are signals containing information inside the subject, respectively, and the signals output to terminals a and b are sent to the DSC. This is a signal that can form a tomographic image by itself if supplied. However, these processed signals do not display images based on FDA's accurate calculation values.

Therefore, in the present invention, FDA is determined in real time by taking the difference between these two processed signals and further differentiating the signal, which is a feature of the present invention.

That is, in order to calculate FDA, a difference calculator 36, a differentiator 38, and an FDA calculator 40 are provided, and when the difference between the two outputs of the moving average circuit 34 is calculated and this difference signal is differentiated, , as mentioned above (2)
The latter term dB(r)/dr of the equation is found. and,
The FDA calculator 40 calculates Δr/(f ₁ −
f ₀ )·B(ro) is given, and the final FDA is calculated.

To explain this FDA calculation using a signal waveform, the fourth
as shown in the figure.

In the figure, a shows received signals of frequencies f ₀ and f ₁ in the same scanning direction, and in this case, as the diagnostic distance becomes deeper, the amount of attenuation of the received signal of frequency f ₁ increases. The difference between these two signals is shown in b, and the differential signal of this difference signal is shown in (c). This differential signal is FDA and represents the amount of attenuation in a minute section in the distance direction, thereby making it possible to display quantitative information inside the subject as an image.

The FDA signal obtained in this way is as described above.
This signal is supplied to the display 22 via the DSC 20.
Tomographic images can be displayed using FDA signals.
In addition, this tomographic image can be displayed in color and superimposed on the tomographic image formed by normal signal processing.In this way, quantitative information can be clearly added to the tomographic image as a morphological image. can be displayed.

Furthermore, FDA values can be displayed in a conventional manner for selectively designated portions, making it possible to obtain FDA information in a short time.

[Effects of the Invention] As explained above, according to the present invention, since the difference between two received signals is calculated and this difference signal is subjected to differential calculation, it is possible to obtain FDA for the entire ultrasonic scanning area. This enables quantitative image display of tomographic images in real time.

Therefore, the hardness and properties of organs or tissues within the subject can be easily determined, and there is an advantage that useful information can be obtained through ultrasound image diagnosis.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing a circuit from emitting ultrasonic waves into a subject to performing FDA calculation in the ultrasonic diagnostic apparatus according to the present invention; Fig. 2 is a graph diagram explaining the principle of FDA calculation; Figure 3 is an explanatory diagram showing the spectrum demodulated from the received signal obtained by two ultrasound waves, Figure 4 is a waveform diagram showing signal conversion in FDA calculation, and Figure 5 is a circuit of a conventional ultrasound diagnostic device. FIG. 2 is a block diagram showing the configuration. 10... Probe, 22... Display, 24... Transmitter/receiver, 26... Signal switch, 28... Quadrature detector, 36... Difference calculator, 38... Differentiator, 40...
...FDA calculator.

Claims (1)

[Claims] 1. A transceiver that transmits and receives a plurality of ultrasonic waves with different frequencies, and a difference calculator that orthogonally detects received signals obtained using two predetermined ultrasonic waves and calculates an intensity difference. , and a differentiator that differentiates the output of the difference calculator by the reciprocating path length of the ultrasonic wave, and is characterized in that the frequency-dependent attenuation constant estimated from the differentiator output is displayed as an image in all operation regions. Ultrasonic diagnostic equipment. 2. An ultrasonic diagnostic apparatus according to claim 1, characterized in that a tomographic image based on the estimated frequency attenuation constant is displayed superimposed on a tomographic image formed in B mode.