JPH088922B2 - Ultrasonic Doppler diagnostic device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a blood flow velocity in a living body,
More particularly, the present invention relates to an ultrasonic Doppler diagnostic apparatus that generates virtual complex interpolated data between actual scan lines in order to improve the scan line density of color flow display.

[0002]

2. Description of the Related Art In an ultrasonic Doppler diagnostic apparatus, in order to improve the S / N ratio of color flow display, ultrasonic waves are transmitted and received about 10 times on the same scanning line and averaged to obtain speed data of scalar quantity. ing. Then, the same calculation is performed for the next scanning line, and the scanning lines that are sequentially scanned are moved to form a two-dimensional color flow image.

Therefore, the complete image time for one frame of the color flow image becomes longer than the complete image time for one frame of the normal echo tomographic image, and the decrease in the frame rate makes it difficult to perform detailed time phase analysis. There was a problem.

Therefore, in order to solve this problem, as shown in FIG. 8, the scanning line density of the black and white echo display and the scanning line density of the color flow display are set to about 2: 1 to display the color flow roughly. We are trying to prevent the frame rate from decreasing. That is, the color flow is displayed by scanning lines shown by broken lines, and the black and white (B / W) echo is displayed by scanning lines shown by solid lines and broken lines. However, since the display is rough as it is, the speed output of the scalar amount is subjected to interpolation processing (scalar interpolation processing) such as Rθ conversion (polar coordinate conversion) in a display system such as a digital scan converter (DSC) to smooth the color flow display. ing.

For example, the autocorrelation values R ₁ and R _{2 at} two points are
As shown in FIG. 9, when R ₁ = A ₁ e ^{j θ} 1 R ₂ = A ₂ e ^{j θ} 2, the respective deviation angles are θ ₁ = Arg {R ₁ } θ ₂ = Arg {R ₂ } And the value to be interpolated is θ = (θ ₁ + θ ₂ ) / 2.

Here, A ₁ is the amplitude of R ₁ and A ₂ is the amplitude of R ₂ .

[0007]

However, in the above-described scalar interpolation processing, when the velocities are spatially distributed near the turnaround velocity, the maximum value of the positive velocity and the maximum value of the negative velocity are averaged. However, there is a problem that it is erroneously estimated to be almost zero, and a blackout phenomenon occurs in the color flow display.

Therefore, in order to solve this problem, for speeds above a predetermined value, the speed interpolation processing is performed in consideration of the turning back condition, or the maximum value of the positive speed and the maximum value of the negative speed are increased. A method of displaying the same color in the vicinity of the value has been proposed.

However, in the above-mentioned scalar interpolation processing,
Since only the argument (velocity) of the autocorrelation value is simply interpolated, there is a problem that the estimation accuracy of the interpolated velocity is poor. Furthermore, in the above-described scalar interpolation processing, as shown in FIG. 10, interpolation is also performed on isolated color noise, which increases the frequency of occurrence of noise, and the SN ratio of the color flow before interpolation. There was a problem that it was worse than that.

The present invention has been made to solve the above problems, and an object thereof is to obtain real part and imaginary part data of a complex autocorrelator output obtained from real scanning lines of a plurality of color flows. Based on the original, complex data interpolated between actual scanning lines is generated by vector interpolation processing that interpolates each component of complex data, the speed is calculated from this data, and the scanning line density of color flow display is improved, An object of the present invention is to provide an ultrasonic Doppler diagnostic apparatus capable of increasing speed estimation accuracy and reducing noise.

[0011]

SUMMARY OF THE INVENTION The present invention was made in view of the above circumstances, the raw body transmits ultrasound pulses at a predetermined repetition cycle, the reflected wave reflected by in vivo kinetic reflector an ultrasonic Doppler diagnostic device which detects a Doppler shift frequency to display the movement velocity of the moving reflector,
In the ultrasonic Doppler diagnostic apparatus which performs interpolation processing for generating interpolation data by incorporation data from the real scan line, the receiving
An autocorrelation calculator that inputs a signal and outputs a complex signal
And the complex signal from the autocorrelation calculator is input,
Average value for averaging the real and imaginary parts of the elementary signal
Arithmetic circuit and averaging output from the average value arithmetic circuit
A real part data interpolation circuit that performs real number unit based Dzu have the data interpolation of the complex signal, is outputted from said average value calculation circuit
Possess and imaginary part data interpolation circuit for performing data interpolation, a and have groups Dzu the imaginary part of the averaged complex signal which, among the real scan line
And a vector interpolation unit for generating an interpolated scan line containing
Scan the real and imaginary parts of the complex signal separately
After averaging along the line, the averaged real number
The feature is that interpolation is performed between the scanning lines separately for the part and the imaginary part .

[0012]

In the ultrasonic Doppler diagnostic apparatus based on the above configuration, the complex output from the autocorrelation calculator is sent to the vector interpolator. The real part data interpolation circuit in the vector interpolator performs data interpolation based on the real part of the complex signal output, and the imaginary part data interpolation circuit in the vector interpolator performs data interpolation based on the imaginary part of the complex signal output.

Data interpolation is performed as described above, virtual complex interpolated data is generated between real scanning lines from complex data on a plurality of real scanning lines, and the motion speed is calculated from this data to calculate the scanning lines in the display. Improves density. Therefore,
Since the interpolation is performed in consideration of the amplitude of the autocorrelation value as well, the estimation accuracy of the interpolated speed can be increased and the loopback determination is not necessary. Further, when a plurality of complex data are averaged in the distance direction, the variance of noise becomes small, so that the frequency of appearance of noise becomes low and the SN ratio is improved. And in the present invention
According to the real part and the imaginary part before interpolation between such scan lines.
It is possible to perform averaging along the scan line individually for several parts.
Noise can be done without degrading the resolution of the image so much.
It is possible to perform interpolation while reducing.

[0014]

EXAMPLES Hereinafter, actual施例of the present invention will be described with reference to FIG.

FIG. 1 is a block diagram showing the configuration of an ultrasonic Doppler diagnostic apparatus according to the present invention. The ultrasonic Doppler diagnostic apparatus includes a probe 1 that transmits and receives ultrasonic waves to and from the living body 100. The probe 1 transmits an electric signal to the probe 1 at a predetermined repetition period, and at the same time, a motion reflector inside the living body 100. A transmitter / receiver 2 for receiving the reception signal of the probe 1 that receives the reflected wave reflected by is connected. Then, the transmitter / receiver 2 scans the ultrasonic pulse beam emitted from the probe 1 by mechanical or electrical angle deflection or the like, and periodically scans the living body 100 with the ultrasonic pulse beam or makes a desired deflection. A scan controller 3 that stops scanning at an angle, an amplifier 4 that amplifies a reception signal received by the transceiver 2, and a quadrature detector 5 that converts the reception signal received by the transceiver 2 into a complex signal are arranged in parallel. Connected,
The scanning controller 3 is connected to a timing signal generator 6 that generates a reference signal input to the quadrature detector 5 and an interpolation control signal input to the vector interpolator 14.

A detector 7 is connected to the amplifier 4, and an A / D converter 8 for converting an analog output of the detector 7 into a digital signal is connected to the detector 7. Further, a digital scan converter (DSC) 9 is connected to the A / D converter 8, and the DSC 9 is connected to the DSC 9.
A D / A converter 10 for converting the output of 9 into an analog signal is connected, and a display 11 is connected to the D / A converter 10.

On the other hand, a clutter removing filter 12 is connected to the quadrature detector 5, and the clutter removing filter 12 is connected.
Includes an autocorrelator 13 for estimating the motion velocity of the motion reflector.
Is connected. Further, the autocorrelator 13 is connected to a vector interpolator 14 that performs vector interpolation processing on the real number part and the imaginary number part of the output of the autocorrelator 13, respectively. A speed calculator 15 that calculates a speed V of a scalar amount from complex data output from 14 and a dispersion calculator 16 that calculates distributed data are connected in parallel, and the speed calculator 15 and the dispersion calculator 16 are connected to each other. Are connected to the DSC 9.

FIG. 2 shows a vector interpolator 14 according to the present invention.
FIG. 3 is a block diagram showing the configuration of FIG.

The vector interpolator 14 comprises a real part data interpolation circuit part 14a and an imaginary part data interpolation circuit part 14b. The real part data interpolation circuit part 14a is a multiplexer 1.
9 and a delay line 17 and an adder 18, and performs data interpolation based on the real part R _x of the complex output of the autocorrelator 13. Similarly, the imaginary part data interpolation circuit part 14b is also composed of a multiplexer 22, a delay line 20, and an adder 21, and performs data interpolation based on the imaginary part R _y of the complex output of the autocorrelator 13. The delay lines 17 and 20 perform delay processing equal to the transmission repetition period.

Here, the principle of the vector interpolation processing will be described.

For example, as shown in FIG. 3, the autocorrelation values R ₁ and R ₂ at two points of the complex data from the actual scanning line in the complex signal output of the autocorrelator 13 are R ₁ = A _{When 1} e ^{j θ} 1 R ₂ = A ₂ e ^{j θ} 2, the value to be interpolated is R = R ₁ + R ₂ .

Next, the operation of this embodiment will be described.
Of the complex signal output of the autocorrelator 13, # in FIG.
The complex data from the actual scanning line i, # i + 2 are directly input to the multiplexers 19 and 22 shown in FIG. 2 and output at the display timing of the actual scanning line.

On the other hand, virtual scan line # i + between real scan lines
The complex data R (i + 1) of 1 is the complex data R (i) of the actual scanning line #i and the complex data R of the actual scanning line # (i + 2).
It is calculated from the average output R _m (i + 1) of (i + 2), and the multiplexer 1 according to the output timing of the virtual scanning line.
The output is switched by switching 9 and 22. That is, it is calculated according to the following formula.

R _m (i + 1) = {R (i) + R (i + 2)} / 2 (1) This vector-interpolated complex data R _m (i + 1) is input to the velocity calculator 15 and the dispersion calculator 16. V (i + 1) = Arg {R _m (i + 1)} (2) σ ² (i + 1) = 1- {| R _m (i + 1) | / R _m0 (i + 1)} (3) Scalar amount Compute the velocity and variance data of. R _m0 (i + 1) is a vector-interpolated amount of the power of the autocorrelator input.

In the present invention, as described above, the autocorrelator 13
Since not only the declination angle but also the amplitude value is taken into consideration in the output from, the black void phenomenon does not occur even when the velocity is spatially distributed in the vicinity of the turnaround velocity. As shown, the point on the real scan line # i + 2 has a velocity of 0.
Even if the point of the actual scanning line #i has color noise, the interpolation value of the scanning line # i + 1 of the virtual color flow to be interpolated has a speed close to 0 and is not displayed.

The following shows to actual施例is performed similarly vector interpolation processing and the upper you施例, it is an aspect of this embodiment, the two points adjacent to the transmission and reception direction of the ultrasonic beam complex The SN ratio is improved by adding the data. That is, as shown in FIG. 5, the ultrasonic Doppler diagnostic apparatus discriminates noise from blood flow by a predetermined threshold value in amplitude when displaying blood flow. However, as shown by the shaded area in FIG. 5, some noise may exceed the threshold value and be mixed into the output of the display. Generally, the variance (σ ² ) of a random signal such as noise is proportional to the reciprocal of the data length (N). Therefore, when the complex data of two points adjacent in the distance direction are added, the variance of noise becomes small and the frequency of occurrence of noise above the threshold becomes low. As a result, the SN ratio of the color flow display is improved.

The operation of this embodiment will be specifically described below.
The configuration of this embodiment is almost the same as that of the above embodiment,
As shown in FIG. 7, the autocorrelator 13 and the vector interpolator 1
4 and the average value calculator 25. Here, in the average value calculator 25, the scanning line is # i-th and the depth is #j.
Th output of autocorrelator 13 and R (i, j), the complex data obtained by averaging the distance direction When _{R m (i, j),} R m (i, j) = {R (i, j ) + R (i, j + 1)} / 2 (4) is calculated.

Similarly, the actual scan line # i + given by the following equation:
The second average value {R _m (i + 2, j)} is calculated.

R _m (i + 2, j) = {R (i + 2, j) + R (i + 2, j + 1)} / 2 (5) Then, the vector interpolator 14 calculates the distance direction calculated by the fourth and fifth equations. Of the virtual color flow scanning line # i + 1th interpolation data R _m (i +
1, j) is calculated from the following equation.

R _m (i + 1, j) = {R _m (i, j) + R _m (i + 2, j)} / 2 (6) Then, the complex interpolation data is sent to the speed calculator 15 and the dispersion calculator 16. Then, the velocity and dispersion data of the scalar amount are calculated from the second and third equations and input to the DSC 9. Then, the DSC 9 superimposes the color flow on the monochrome echo image and displays it on the display 11. Here, the variance of the variance data calculated by averaging the complex data is small, and the frequency of occurrence of noise above the threshold is low.

In the above embodiment shown in FIG. 6,
Data of four points R (i, j), R (i, j + 1), R (i
The complex data R (i + 1, j) of the virtual scanning line # i + 1 is obtained by + 2, j) and R (i + 2, j + 1), but the data is not limited to this and may be data of 6 points, 8 points, or the like. .

[0032]

As described above, according to the ultrasonic Doppler diagnostic apparatus of the present invention, the real part data interpolation circuit in the vector interpolator performs data interpolation based on the real part of the complex output from the autocorrelation calculator. At the same time, the imaginary part data interpolation circuit in the vector interpolator performs data interpolation based on the imaginary part of the complex output from the autocorrelation calculator, and the virtual complex interpolation data between the complex data in the multiple actual scanning lines and the actual scanning lines. Since it is configured so as to improve the scanning line density, the interpolation is performed in consideration of the amplitude of the autocorrelation value, so that the estimation accuracy of the interpolated speed can be increased, and the return determination is not necessary, and It is possible to prevent the blackout phenomenon. Furthermore, when averaging a plurality of complex data in the distance direction, noise can be reduced and the S / N ratio of the color flow can be improved, whereby a smooth and continuous color flow image can be obtained.

[Brief description of drawings]

1 is a block diagram showing a configuration of an ultrasonic Doppler diagnosis device engaging Ru real施例the present invention.

FIG. 2 is a block diagram showing a configuration of a vector interpolator according to the present invention.

FIG. 3 is a diagram for explaining the principle of vector interpolation processing according to the present invention.

FIG. 4 is an explanatory diagram for explaining reduction of color noise by vector interpolation processing according to the present invention, and FIG. 4 (a) is a diagram showing display positions of captured data and interpolation data,
(B) is a figure which shows the speed of each display position.

FIG. 5 is a diagram showing a relationship between noise amplitude and blood flow amplitude histogram.

FIG. 6 is a diagram for explaining vector interpolation processing after averaging processing in the distance direction according to the present invention.

7 is a block diagram showing a configuration of a part of an ultrasonic Doppler diagnostic apparatus according to the actual施例of the present invention.

FIG. 8 is a diagram showing scanning line densities of black and white echo and color flow.

FIG. 9 is a diagram for explaining a conventional scalar interpolation process.

FIG. 10 is a diagram for explaining that color noise appears in a conventional scalar interpolation process.

[Explanation of symbols]

 1 probe 2 transceiver 11 indicator 13 autocorrelator 14 vector interpolator 14a real part data interpolation circuit part 14b imaginary part data interpolation circuit part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Okada 6-22-1, Mure, Mitaka City, Tokyo Aloka Co., Ltd. (56) References JP-A-1-305936 (JP, A) JP-A-2- 283358 (JP, A) JP-A-5-146440 (JP, A)

Claims (1)

[Claims] 1. An ultrasonic Doppler device for displaying ultrasonic waves of a moving reflector by transmitting ultrasonic pulses to a living body at a predetermined repetition period and detecting a Doppler shift frequency of a reflected wave reflected by the in-vivo moving reflector. a diagnostic apparatus, the ultrasonic Doppler diagnostic apparatus which performs interpolation processing for generating interpolation data by incorporation data from the real scan line, the received signal is inputted, and the self correlation operation unit for outputting a complex signal, the autocorrelation The complex signal from the calculator is input and the complex signal
Value arithmetic for averaging the real and imaginary parts of the number
Circuit and the averaged complex signal output from the average value calculation circuit
A real part data interpolation circuit for performing data interpolation have groups Dzu the real part of the item, averaged output from said average value calculation circuit
Have a, and the imaginary part data interpolation circuit for performing data interpolation have groups Dzu the imaginary part of the complex signal that has been interpolated between the actual scanning line
It includes a vector interpolation unit for generating a scan line, and the individual scanning lines for real and imaginary parts of the complex signal
After averaging along, the averaged real part and
An ultrasonic Doppler diagnostic apparatus characterized in that interpolation is performed between scanning lines individually for an imaginary part .