JP2690000B2 - Ultrasound Doppler diagnostic device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic Doppler diagnostic apparatus for detecting the motion velocity of a motion reflector such as blood, and more particularly, an ultrasonic Doppler diagnostic apparatus having a two-dimensional blood flow display function for two-dimensionally displaying blood flow. Regarding the device.

[0002]

2. Description of the Related Art Conventionally, ultrasonic Doppler diagnostic devices have been used in the medical field. This type of device transmits an ultrasonic wave into a living body and detects the Doppler shift of the frequency of the reflected wave. If the object reflecting the ultrasonic waves is a moving object such as blood, the Doppler shift frequency depends on the velocity of this reflector. That is, the ultrasonic Doppler diagnostic apparatus is an apparatus that obtains and displays velocity information of a moving reflector in a living body to obtain significant information for medical treatment.

The information thus obtained must be displayed by a doctor intuitively and as easily as possible. In order to perform such a display, an image display capable of two-dimensional display is used.

FIG. 6 shows the configuration of an ultrasonic Doppler diagnostic apparatus according to a conventional example. This device has substantially the same configuration as the two-dimensional blood flow imaging device disclosed in Japanese Patent Publication No. 62-44494 of the present applicant.

This device comprises a probe 2 which comes into contact with a living body 1. The probe 2 has a predetermined number of piezoelectric vibrators and is excited by the transceiver 3. That is, according to the signal of the predetermined repetition frequency from the transceiver 3, the probe 2
Generates ultrasonic vibrations, and reflected echoes from the blood flow in the living body are captured by the transceiver 3 as electric signals.

The output of the transceiver 3 is taken into the quadrature detector 4. The quadrature detector 4 converts the reflected echo into two types of complex signals that are 90 ° out of phase with each other. For this reason,
The mixers 4a and 4b are provided for taking in the reference signals 5a and 5b which are 90 ° out of phase with each other from the timing signal generator 12 and mixing them with the reflected echoes. The timing signal generator 12 gives the transceiver 3 a repetition frequency as a clock.

Low-pass filters 6a and 6b are connected to the subsequent stages of the mixers 4a and 4b, respectively. Mixer 4
Since the outputs of a and 4b include the components of the sum frequency and the difference frequency of the electric signal related to the reflection echo and the reference signals 5a and 5b, in this conventional example, the low-pass filter 6 is used.
Only the difference frequency component is extracted by a and 6b.
This difference frequency component is a Doppler shift frequency component.

An A / D converter 7 is provided after the quadrature detector 4.
a and 7b are provided. This A / D converter 7a, 7
b converts the difference frequency component into a digital signal.
The high-pass filters 8a and 8b provided at the subsequent stage of the A / D converters 7a and 7b remove the low frequency of the Doppler shift frequency, thereby reflecting from the stationary part or the slow-moving part in the living body. It is a means for removing clutter and the like caused by the above, and is specifically configured by a delay line canceller or the like.

Further, in this conventional example, an autocorrelator 9 is provided. The autocorrelator 9 calculates R and I by the following formula.

R = x1x2 + y1y2 = 4sin ² (2πfdT / 2) cos (2πfdT) I = x2y1-x1y2 = 4sin ² (2πfdT / 2) sin (2πfdT) However, the repetition period is T, the Doppler shift frequency is fd, and the high frequency is high. The output of the high-pass filter 8a is x1, and the high-pass filter 8 is
High-pass filter 8 in which the output of b is delayed by y1 and T
High-pass filter 8 with the output of a delayed by x2, T
The output of b is y2.

The angle vector R thus obtained
And I (or the average value of R and I for noise removal), the deflection angle tan ⁻¹ (I / R) is obtained. This calculation is performed by the argument calculator 11. The declination calculator 11 can be configured as, for example, a ROM that stores a table that associates the values of I and R with the values of the declination. The declination has a value proportional to the Doppler shift frequency fd.

On the other hand, the electric signal related to the reflected echo output from the transceiver 3 is supplied to the detector 13. The detector 13 detects the signal and outputs the signal. This signal represents a black and white tomographic image and is supplied to the digital scan converter 14 and is two-dimensionally mapped. As a result, the display on the image display 15 is performed. Here, since the deviation angle corresponds to the Doppler shift frequency fd, it is possible to continuously measure and display the blood flow distribution using this deviation angle. For example, the screen can be colored according to the deviation information.

[0013]

However, in the conventional ultrasonic Doppler diagnostic apparatus, when the received signal level is small and is buried in noise even when the reflector such as blood flow is moving. However, there is a problem that it becomes difficult to detect the motion velocity, and so-called black spots occur in the flow region (the region where blood flow exists) displayed by color. On the contrary, in some cases, an isolated noise-like color is formed at a place where blood flow or the like should not exist.
As described above, the blood flow display may be discontinuous or may cause unnecessary coloring.

The present invention has been made to solve the above problems, and it is possible to interpolate even small black spots and remove isolated noise-like colors, resulting in smoother smoothing. It is an object of the present invention to provide an ultrasonic Doppler diagnostic apparatus capable of displaying a converted color image.

[0015]

In order to achieve such an object, the present invention provides N times (N:
(Integer) Remains in the living body while changing the direction of wave transmission each time it is transmitted
Repeating cycle of ultrasonic beam on moving reflector such as blood flow
Transmit at T and receive the reflection echo from the motion reflector
Transmitting / receiving means for outputting as an electric signal, and the reflection echo
The electrical signal related to the signal is detected and the signal showing the black and white tomographic image is output.
Detector and the electrical signal related to the reflected echo
By transmitting the wave and calculating the autocorrelation,
And sequentially, the means for obtaining the declination vector and the time for each NT
Multiple data obtained by multiple past transmissions at intervals
By sequentially averaging the declination vectors for each transmission,
Moving average that averages multiple different transmission directions
The value of the moving reflector is calculated based on the obtained moving average value.
Means for obtaining a declination indicating the degree, and an output signal of the detector
Based on the declination and the velocity of the motion reflector in the black and white tomographic image
And a display unit for displaying the image according to the color .

[0016]

In the present invention, they are adjacent to each other along the scanning direction.
Of the ultrasonic wave transmission directions
The moving average of the tor is calculated. Further, the deviation angle is calculated based on this moving average value. Therefore, the other
Even if the tendency to differ from the deflection angle vector obtained by double several ultrasonic beams, for example, tend like cause black spots and isolated noise-like color had emerged, this tendency is eliminated by the averaging, A more visible and accurate movement speed display is realized.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. The same components as those in the conventional example shown in FIG.

FIG. 1 shows the configuration of an embodiment of the present invention. In this embodiment, the autocorrelator 9 and the declination calculator 1 are used.
The feature is that an inter-line smoother 10 is provided between the two. FIG. 2 shows the configuration of this interline smoother 10.

As shown in this figure, the interline smoother 10 includes delay lines 100a and 101a. These are cascaded and each delays the signal related to the input by NT. However, T is a repetition period, N is an integer and is the number of ultrasonic beam transmissions in each transmission direction. Since the input to the delay line 100a is the R deflection angle vector, the output of the delay line 100a is delayed by NT, that is, the delay line 101.
The output of "a" is obtained by further delaying this by NT. The interline smoother 10 further includes a delay line 100.
b and 101b, which also operate in the same way as the delay lines 100a and 101a with respect to the argument vector of I.

The delay lines 100a and 101a are
It is connected to the adder 102a via the three multipliers 104a, 105a, and 106a. Multipliers 104a, 10
5a and 106a are the declination vector of R and NT, respectively.
The declination vector of R after the delay and the declination vector of R after the delay of 2NT are multiplied by the weights of W1, W2, and W3. Each multiplier 104a, 105a, 106a which is the value multiplied by the weight
Is output to the adder 102a. Adder 102
The output of a is supplied to the divider 103a, and W1 + W2 + W
Divided by 3, i.e. by the sum of the weights. Then, a weighted average of the inputs of the multipliers 104a, 105a, 106a is obtained. The interline smoother 10 of this embodiment outputs this as a moving average value of the R argument vector. Since the inter-line smoother 10 obtains a moving average value for the argument vector of I, three line multipliers 104b,
105b, 106b, adder 102b, divider 103b
Also equipped with. Since this is the same operation, the description is omitted here.

Next, the moving average calculation of the deviation angle vector in this embodiment will be described in more detail.

In this embodiment, as shown in FIG.
Transmission of the ultrasonic beam is executed while scanning. Wave transmission is performed N times (hereinafter, N = 8) in one direction. Therefore, as shown in FIG. 4, 8 in the (n-1) th direction.
Beams correspond to the nth direction, and further to the nth direction.
Eight beams also correspond to the + 1st direction.

Now, in the case where the autocorrelator 9 is configured to average and output eight argument vectors in the same direction for noise removal, the autocorrelator 9 is shown in FIG. Outputs Dn-1, Dn, Dn + 1, ... Are obtained at such timing. These are input to the interline smoother 10.

[0024] Then, when considering taking some point, delay line 100a, the output of 100b becomes an output of the autocorrelator 9 according the input line between the smoother 10 to one before the beam direction, delay line 101a, The output of 101b is the output of the autocorrelator 9 in the beam direction two beams before the input of the interline smoother 10. For example, when the average value Dn + 1 of the argument vector obtained by transmitting the ultrasonic beam in the (n + 1) th direction is output from the autocorrelator 9, the outputs of the delay lines 100a and 100b are D.
n, the output of the delay lines 101a and 101b is Dn-1
Becomes In this case, the outputs of the adders 102a and 102b are And the outputs of the dividers 103a and 103b are

(Equation 1) Becomes

The divider 103a thus obtained,
The output of 103b becomes a moving average value as described above. This is because the outputs of the autocorrelator 9 obtained for each direction are averaged. This moving average value R'and I
′ Is supplied to the declination calculator 11 and declination tan ⁻¹ (I ′ /
R ') is required.

In this way, when the deviation angle is obtained and displayed based on the moving average value, noise is included in the output of the autocorrelator 9 obtained from several adjacent transmitting directions, and the autocorrelator 9 is included. Even if it is thought that black spots or isolated colors will occur if the declination is immediately obtained from the output of
Blackouts and isolated colors do not occur. As a result, the confusingness of the display is reduced, and more accurate and accurate speed display is realized.

In the above description, the average value of the deflection vector is calculated as a weighted average, but this may be a simple average. Further, although the score for obtaining the moving average value is set to three points, a larger score may be taken. Weighting is
Various methods such as uniform weighting, linear weighting, and Gaussian weighting can be applied.

FIG. 5 shows another structure of the interline smoother 10. This figure is an example configured as a video sweep integrator. As shown in the figure, the outputs of the autocorrelator 9 and the outputs of the multipliers 202a and 202b are added by the adders 200a and 200b, and the result of the addition is delayed by NT by the delay lines 201a and 201b. The output of 201b is input to multipliers 202a and 202b and multiplied by β. Further, the outputs of the adders 200a and 200b are divided by N by the dividers 203a and 203b and output as a moving average value. However, β = 1−2 ^−N . Even in this case, the same effect as that of the inter-line smoother 10 having the above-described configuration can be obtained, and further downsizing can be realized.

[0029]

As described above, according to the present invention,
Since the deviation angle is obtained from the value obtained by moving and averaging the deviation vector along the scanning direction, the occurrence of black spots and isolated noise-like colors is suppressed, and a more visible and accurate motion velocity display is realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an ultrasonic Doppler diagnostic apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram showing the configuration of an interline smoother in this embodiment.

FIG. 3 is a diagram showing a scanning direction of an ultrasonic beam.

FIG. 4 is a timing chart showing the operation of the interline smoother in this embodiment.

FIG. 5 is a block diagram showing another configuration of an inter-line smoother.

FIG. 6 is a block diagram showing a configuration of an ultrasonic Doppler diagnostic apparatus according to a conventional example.

[Explanation of symbols]

 2 probe 3 transceiver 4 quadrature detector 9 autocorrelator 10 interline smoother 11 declination calculator 12 timing signal generator 13 detector 15 image display

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-3-39148 (JP, A) JP-A-58-188433 (JP, A) JP-A-3-80842 (JP, A) JP-A-3- 151944 (JP, A)

Claims (1)

(57) [Claims] 1. N times per transmission direction (N: integer)
An ultrasonic beam is repeatedly transmitted to a motion reflector such as a bloodstream existing in a living body at a cycle T while changing the wave transmission direction every time a wave is transmitted, and a reflection echo from the motion reflector is received. A wave transmitting / receiving means for wavering and outputting as an electric signal, a detector for detecting an electric signal related to the reflection echo and outputting a signal representing a black and white tomographic image, and a quadrature detection for the electric signal related to the reflection echo and further self-detecting the electric signal. By calculating the correlation, it is possible to obtain the declination vector one after another by each wave transmission and the past wave transmissions with a time interval of NT.
Sequentially averages multiple declination vectors generated each time
As a result, the different transmission directions are targeted for averaging.
Means for obtaining a moving average value, and a deviation angle indicating the velocity of the motion reflector based on the obtained moving average value, and a motion reflector on a black-and-white tomographic image based on the output signal of the detector and the deviation angle. An ultrasonic Doppler diagnostic apparatus, comprising: a display unit that displays a color according to the speed of the.