JPH09206304A - Ultrasonograph - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonograph which can make 4 point interpolation operation and can indicate a blood speed correctly even with speed aliasing when a colored image of blood flow is displayed. SOLUTION: A 4 point code judging means 19 and a threshold processing means 20 are installed before a 4 point interpolation operation means 15 inside a color blood flow image display of this device. The 4 point code judging means 19 is to judge whether codes at 4 points surrounding a point to be examined are the same or not, and the threshold processing means 20 is to judge whether the absolute value of the speed at the 4 points is above the threshold previously set for judging the speed aliasing, and to conduct the speed processing against the speed aliasing even if the absolute value is above the threshold only by one point. And a code inversion processing means 21 is installed after the 4 points interpolation operation means 15. The code inversion processing means 21 is to conduct the code inversion processing when the absolute value of the result of the 4 point interpolation operation is above the critical speed for detection. Using such means, the 4 points interpolation operation can be made correctly and a correct blood flow speed can be indicated even when there is a speed aliasing in displaying colored blood flow images.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic diagnostic apparatus for transmitting and receiving ultrasonic waves to and from a subject to obtain a black-and-white tomographic image of a diagnostic site and a color blood flow image which is superposed and displayed on an image display unit. In particular, the present invention relates to an ultrasonic diagnostic apparatus that can correctly perform 4-point interpolation calculation even when velocity aliasing occurs in the display of a color blood flow image, and can display a correct blood flow velocity.

[0002]

2. Description of the Related Art A conventional ultrasonic diagnostic apparatus of this type is shown in FIG.
As shown in FIG. 1, a probe 1 that transmits and receives ultrasonic waves in the subject.
And an ultrasonic wave transmitting / receiving unit 2 for driving the probe 1 to emit an ultrasonic wave and receiving the reflected wave to obtain an echo signal.
And a phasing circuit 3 for inputting the reflected echo signal from the ultrasonic wave transmitting / receiving unit 2 to perform receiving focus processing, and a receiving signal from the phasing circuit 3 for inputting a black-and-white tomographic image of a diagnostic region. A black-and-white tomographic image display unit 4 for generating, a color blood flow image display unit 5 for receiving a received signal from the phasing circuit 3 and extracting blood flow information to generate a color blood flow image, and the black and white tomographic image A color image display section 6 for mixing the image data from the image display section 4 and the color blood flow image display section 5 and displaying the black-and-white tomographic image and the color blood flow image in an overlapping manner. In the image display unit 5, in order to convert the velocity component of the blood flow from the ultrasonic transmission / reception coordinate system to the image display coordinate system, four points surrounding the target point are extracted, interpolation calculation is performed, and coordinate conversion is performed. .

The black-and-white tomographic image display section 4 receives the received wave signal output from the phasing circuit 3, detects the received wave signal, and compresses the received wave signal. Regarding the output signal from the processing circuit 7, the data of the ultrasonic transmission / reception coordinate system (r, θ) is displayed on the display coordinate system (x,
y) and a monochrome display circuit 8 for coordinate conversion. Also,
The color blood flow image display unit 5 inputs the received wave signal output from the phasing circuit 3 and calculates the velocity, dispersion, and intensity as blood flow information from the received wave signal by color flow mapping (C).
FM) arithmetic circuit 9 and a color display circuit 1 for coordinate-converting the data of the ultrasonic transmission / reception coordinate system (r, θ) with respect to the output signal from the CFM arithmetic circuit 9 to the display coordinate system (x, y).
It consists of 0 and. Further, reference numeral 11 denotes a mixing circuit for mixing the black and white tomographic image output from the black and white display circuit 8 and the color blood flow image output from the color display circuit 10.

The internal structure of the color display circuit 10 in the color blood flow image display section 5 is as shown in the block diagram of FIG. That is, an x, y address generating means 12 for generating coordinate points (x, y) to be displayed on the image display unit 6 shown in FIG. 1 and a coordinate point (x, y) generated by the x, y address generating means 12. ) Corresponding to the ultrasonic transmission / reception coordinate system (r, θ) and the r, θ coordinate conversion means 13 for outputting the interpolation coefficients a, b, and the ultrasonic transmission / reception by receiving the output signal from the CFM arithmetic circuit 9 shown in FIG. The frame memory 14 to be written in the coordinate system (r, θ) and this frame memory 1
4 to 4 as shown in FIG. 3 (b), the four nearest points surrounding the target point (r, θ) are read out and the following equation (1) is calculated for the above interpolation coefficients a and b. Computing means 15,
The display memory 16 writes image data to be displayed on the image display unit 6. However, i is the r, θ address of the frame memory 14.

[0005]

However, in the four-point interpolation calculation in such a conventional ultrasonic diagnostic apparatus,
The CFM calculation circuit 9 in the color blood flow image display unit 5 shown in FIG.
Of the blood flow information output from, "dispersion" and "strength" have no positive and negative values, so there is no problem, but "velocity"
There are positive and negative signs, and when the maximum display speed (detection limit speed) is exceeded, the sign may be inverted and displayed (speed aliasing occurs), and there are the following problems.

In FIG. 6, the horizontal axis represents the coordinate value of r or θ,
The vertical axis shows the value of speed v, and the maximum positive display speed is + V.
max, which indicates the maximum negative display speed by -Vmax.
The relationship of the blood flow image between points is shown. And FIG. 6 (a)
If the velocities v ₁ and v ₂ of the two points have the same sign,
When the speeds v ₁ and v _{2 at the} points have different signs but the positive and negative maximum display speeds Vmax are less than or equal to speed aliasing does not occur, the two speeds v ₁ and v _{2 at the} two points have different signs. And the case where velocity aliasing occurs.

In the cases of FIGS. 6 (a) and 6 (b), velocity aliasing has not occurred in either case, and the color display circuit 10 of the conventional configuration shown in FIG.
If a four-point interpolation calculation is performed using, the interpolation value v (x, y)
Is obtained correctly. However, in the case of FIG. 6C, the broken line portion 17 exceeding the maximum negative display speed −Vmax causes speed aliasing and the sign is inverted, and the maximum positive display speed + V
It is folded back to the max side and displayed as a solid line portion 18. At this time, in the conventional example, it is assumed that the speed changes abruptly between the speeds v ₁ and v ₂ between the two points resulting from the speed aliasing, and the color display circuit 10 causes the speed v of these two points to change. _The interpolation calculation is performed by the above-mentioned formula (1) using ₁ and v ₂ , and the wrong velocity value v ′ (x, y) is obtained. Therefore, the color blood flow image displayed by fetching the output signal from the color display circuit 10 has a wrong color display and cannot be effectively used for image diagnosis.

Therefore, the present invention addresses such a problem and can correctly perform 4-point interpolation calculation even when velocity aliasing occurs in the display of a color blood flow image, and display a correct blood flow velocity. It is an object of the present invention to provide an ultrasonic diagnostic apparatus capable of performing the above.

[0009]

In order to achieve the above object, an ultrasonic diagnostic apparatus according to the present invention includes a probe for transmitting and receiving ultrasonic waves in a subject, and an ultrasonic wave driven by the probe. And an ultrasonic wave transmitting / receiving unit that receives the reflected wave and obtains an echo signal, and a phasing circuit that inputs the reflected echo signal from the ultrasonic wave transmitting / receiving unit and performs receiving focus processing,
A black-and-white tomographic image display section that inputs a received wave signal from this phasing circuit to generate a black-and-white tomographic image of the diagnosis site and a received wave signal from the phasing circuit to extract blood flow information and color The color blood flow image display unit for generating the blood flow image of the above and the image data from the black and white tomographic image display unit and the color blood flow image display unit are mixed, and the black and white tomographic image and the color blood flow image are superimposed and displayed. The color blood flow image display unit is provided, and four points surrounding the target point are extracted to convert the velocity component of blood flow from the ultrasonic transmission / reception coordinate system to the image display coordinate system in the color blood flow image display unit. In the ultrasonic diagnostic apparatus for performing interpolation calculation to convert coordinates, in the preceding stage of the 4-point interpolation calculation means in the color blood flow image display unit,
It is determined whether or not the signs of the four points surrounding the target point are the same 4
The point code determination means determines whether or not the absolute speed values at the four points exceed a preset threshold value for determining the speed aliasing. If even one point is exceeded, the speed aliasing is performed. A threshold value processing means for performing speed conversion processing is provided as being caused, and the absolute value of the result of the 4-point interpolation calculation exceeds the detection limit speed after the 4-point interpolation calculation means. A code inversion processing means for performing a code inversion process is provided.

Further, the threshold value processing means may be capable of being arbitrarily changed and set depending on the site of the subject within a range in which the threshold value for discriminating the speed aliasing is smaller than the detection limit speed.

[0011]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing an embodiment of an ultrasonic diagnostic apparatus according to the present invention. The ultrasonic diagnostic apparatus transmits and receives ultrasonic waves to and from a subject to obtain a black-and-white tomographic image of a diagnostic region and a color blood flow image, which is displayed in an overlapping manner on an image display unit. As shown in FIG. , The probe 1, the ultrasonic wave transmitting / receiving unit 2, the phasing circuit 3, the black and white tomographic image display unit 4, and the color blood flow image display unit 5
And a mixing circuit 11 and an image display unit 6.

The probe 1 transmits / receives ultrasonic waves to / from the subject. Although not shown in the figure, the probe 1 has a transducer for generating ultrasonic waves and receiving a reflected echo. There is. The ultrasonic wave transmitting / receiving unit 2 drives the probe 1 to emit ultrasonic waves and receives the reflected wave to obtain an echo signal. Although not shown, the ultrasonic wave transmitting / receiving unit 2 drives the probe 1 inside. It has a pulser for sending a pulse and a preamplifier for amplifying the reflected echo signal received by the probe 1. Further, the phasing circuit 3 inputs the reflected echo signal output from the ultrasonic transmission / reception unit 2 and performs receiving focus processing, and converts the received signal from each transducer element in the probe 1 into a received signal. It has a plurality of delay circuits that give a predetermined delay time, and an adder that adds the received signals whose phases are aligned by these delay circuits.

The black-and-white tomographic image display section 4 receives the wave-receiving signal from the phasing circuit 3 to generate a black-and-white tomographic image of the diagnostic region, and receives the wave-receiving signal output from the phasing circuit 3. A black-and-white video processing circuit 7 for inputting, detecting and compressing the received signal, and data output from the black-and-white video processing circuit 7 in the ultrasonic transmission / reception coordinate system (r, θ) is displayed in the display coordinate system (x , Y) and a black-and-white display circuit 8 for coordinate conversion. The color blood flow image display unit 5 receives the received signal from the phasing circuit 3 and extracts blood flow information to generate a color blood flow image, which is output from the phasing circuit 3. Color flow mapping (C that inputs a received signal and calculates velocity, dispersion, and intensity as blood flow information from the received signal
FM) arithmetic circuit 9 and the output signal from this CFM arithmetic circuit 9 is used to coordinate-convert the data of the ultrasonic transmission / reception coordinate system (r, θ) into the display coordinate system (x, y) and R (red),
The color display circuit 10 performs color conversion into G (green) and B (blue).

The mixing circuit 11 mixes the monochrome tomographic image output from the monochrome display circuit 8 with the color blood flow image output from the color display circuit 10. Then, the image display unit 6 inputs the data obtained by mixing the image data from the black and white tomographic image display unit 4 and the color blood flow image display unit 5 by the mixing circuit 11, and superimposes the black and white tomographic image and the color blood flow image. It is displayed by a color TV monitor.

The internal structure of the color display circuit 10 in the color blood flow image display section 5 is as shown in the block diagram of FIG. That is, an x, y address generating means 12 for generating coordinate points (x, y) to be displayed on the image display unit 6 shown in FIG. 1 and a coordinate point (x, y) generated by the x, y address generating means 12. ) Corresponding to the ultrasonic transmission / reception coordinate system (r, θ) and the r, θ coordinate conversion means 13 for outputting the interpolation coefficients a, b, and the ultrasonic transmission / reception by receiving the output signal from the CFM arithmetic circuit 9 shown in FIG. The frame memory 14 to be written in the coordinate system (r, θ) and this frame memory 1
4 to 4 as shown in FIG. 3B, the four nearest points surrounding the target point (r, θ) are read out and the above-mentioned interpolation coefficients a and b are calculated by the above-mentioned equation (1). Computing means 15,
It has a display memory 16 for writing image data to be displayed on the image display section 6.

Here, in the present invention, in the color display circuit 10 in the color blood flow image display section 5, as shown in FIG. 2, a 4-point code determination means 19 is provided in front of the 4-point interpolation calculation means 15. A threshold value processing means 20 is provided, and a sign inversion processing means 21 is provided at the subsequent stage of the four-point interpolation calculation means 15.
Is provided. The 4-point code determination means 19 is shown in FIG.
It is determined whether or not the signs of four points surrounding the target point (r, θ) shown in (b) are the same. Further, the threshold value processing means 20 determines whether or not the absolute velocity values of the four points surrounding the target point (r, θ) exceed a preset threshold value ± Vth for discriminating the velocity aliasing. If any of the points is exceeded, speed conversion processing is performed assuming that speed aliasing has occurred. Further, the sign reversal processing means 21 performs the sign reversal processing for the absolute value of the result of the four-point interpolation calculation by the four-point interpolation calculation means 15 that exceeds the blood flow detection limit speed.

Next, the color display circuit 1 in the color blood flow image display section 5 in the ultrasonic diagnostic apparatus configured as described above.
The operation of 0 will be described with reference to FIGS. 3 and 4.
First, as shown in FIG. 3A, the velocity value of the blood flow to be displayed at the coordinates for the display memory generated by the x, y address generating means 12 shown in FIG. 2 is v (x, y), Figure 3
As shown in (b), the r, θ coordinate conversion means 1 shown in FIG.
It is assumed that the velocity value v (r, θ) after the r, θ coordinate conversion in 3 is obtained. In this case, the four nearest points of the actual velocity data surrounding v (r, θ) Is read from the frame memory 14 shown in FIG.
The subsequent 4-point code determination means 19 makes the determination.

At this time, in FIG. 4 showing the relationship of blood flow images between two points as in FIG. 6, if all four points have the same sign as shown in FIG. 4 (a) (2 in FIG. 4). Although the relationship between the points is shown in the figure, the relationship between the four points is actually shown). However, the processing of the next threshold value processing means 20 is ignored, and the following four-point interpolation calculation means 15 is used to calculate the above equation (1). 4) interpolation calculation is performed to obtain an interpolation value v (x, y). After that, the processing of the next sign inversion processing means 21 is ignored, and the obtained interpolation value v (x, y) is written in the display memory 16 as it is.

Further, as shown in FIG. 4 (b), when the four points straddle regions of different signs, the threshold value processing means 20 sets the speed absolute values of the four points preset. It is determined whether or not the threshold value for aliasing determination ± Vth is exceeded. In this case, when all of the above four points are within the range of ± Vth as shown in FIG. 4B, it is considered that velocity aliasing has not occurred, and the following four-point interpolation calculation means 15 calculates the above equation ( The 4-point interpolation calculation shown in 1) is performed to obtain the interpolation value v (x, y). After that, the processing of the next sign inversion processing means 21 is ignored, and the obtained interpolation value v (x, y) is written in the display memory 16 as it is. The threshold value is, for example, 1/2 Vmax ≦
It is sufficient to set Vth ≦ Vmax.

Further, as shown in FIG.
If the points extend over the regions of different signs, and the threshold value processing means 20 determines that the absolute velocity values of the four points exceed even the preset threshold value ± Vth by one point,
Considered as causing velocity aliasing. At this time, as shown in FIG. 4 (c), the threshold value processing means 20 returns the solid line portion 18 folded back to the + Vmax side to the original position of the broken line portion 17 on the −Vmax side and returns the speed. By performing the conversion process, for example, the positive velocity v ₂ is converted to (v ₂ −2Vmax). Then, using the value after the speed conversion processing, the following four-point interpolation calculation means 15 performs the four-point interpolation calculation represented by the above-mentioned equation (1) to obtain the correct interpolation value v (x, y). After that, v (x,
The absolute value of y) is the maximum display speed (detection limit speed) ± Vmax
If it exceeds, the sign reversal processing means 21 performs sign reversal processing. That is, the inversion processing of v (x, y) ± 2Vmax is performed. In this case, 2Vmax is added when the value of v (x, y) is negative, and 2Vmax is subtracted when the value of v (x, y) is positive. Then, the value of the processing result thus obtained is written in the display memory 16. The speed conversion process by the threshold value processing means 20 means the unification of the signs of the four points. In the example of FIG. 4C, the unification of the signs is made negative, but the signs may be made positive. .

The threshold value ± Vth for determining the speed aliasing set in the threshold value processing means 20.
May be arbitrarily set depending on the site of the subject within the range of the detection limit speed ± Vmax. Further, in FIG. 2, the positions of the 4-point code determination means 19 and the threshold value processing means 20 may be replaced with each other.

[0022]

Since the present invention is constructed as described above,
In front of the four-point interpolation calculation means in the color blood flow image display unit, four-point code determination means for determining whether or not the four points surrounding the target point have the same code, and the absolute velocity values of the four points are preset. It is determined whether or not a threshold for discriminating speed aliasing is exceeded, and if even one point is exceeded, threshold processing means for performing speed conversion processing assuming that speed aliasing has occurred. By providing the sign reversal processing means for performing the sign reversal processing for the absolute value of the result of the four-point interpolation calculation exceeding the detection limit speed after the four-point interpolation calculation means, the color reversal processing means is provided. Even when velocity aliasing occurs in the display of the blood flow image, the 4-point interpolation calculation can be correctly performed, and the correct blood flow velocity display can be performed.
Therefore, the color blood flow image can be displayed correctly and can be effectively used as an image diagnosis.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of an ultrasonic diagnostic apparatus according to the present invention and a conventional example.

FIG. 2 is a block diagram showing an internal configuration of a color display circuit in a color blood flow image display unit.

FIG. 3 is a graph showing a state of coordinate conversion in a 4-point interpolation calculation.

FIG. 4 is an explanatory diagram showing an example of interpolated values of blood flow velocity in the present invention.

FIG. 5 is a block diagram showing an internal configuration of a color display circuit in a color blood flow image display unit according to a conventional example.

FIG. 6 is an explanatory diagram showing an example of interpolated values of blood flow velocity in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Probe 2 ... Ultrasonic wave transmission / reception part 3 ... Phasing circuit 4 ... Monochrome tomographic image display part 5 ... Color blood flow image display part 6 ... Image display part 9 ... CFM arithmetic circuit 10 ... Color display circuit 11 ... Mixing circuit 12 ... x, y address generation means 13 ... r, θ coordinate conversion means 14 ... frame memory 15 ... 4-point interpolation calculation means 16 ... display memory 19 ... 4-point code determination means 20 ... threshold value processing means 21 ... sign inversion processing means

Claims (2)

[Claims] 1. A probe for transmitting and receiving ultrasonic waves to and from a subject, and an ultrasonic transceiver for driving the probe to emit ultrasonic waves and receiving reflected waves to obtain echo signals.
A phasing circuit for inputting the reflected echo signal from the ultrasonic wave transmitting / receiving unit to perform receiving focus processing, and a black and white tomographic image for inputting the receiving signal from the phasing circuit to generate a black and white tomographic image of the diagnostic region A display unit, a color blood flow image display unit that inputs a received signal from the phasing circuit and extracts blood flow information to generate a color blood flow image, the black and white tomographic image display unit and the color blood flow image It has a color image display section for displaying the black-and-white tomographic image and the color blood flow image by superimposing them by mixing the image data from the display section, and displaying the velocity component of the blood flow in the color blood flow image display section. An ultrasonic diagnostic apparatus for extracting four points surrounding a target point and performing interpolation calculation to perform coordinate conversion when converting from the ultrasonic transmission / reception coordinate system to the image display coordinate system. In front of the means, 4 surrounding the target point
4-point code determination means for determining whether or not the signs of the points are the same,
It is determined whether or not the absolute speed values at the above four points exceed a preset threshold value for determining speed aliasing. If even one point is exceeded, it is assumed that speed aliasing has occurred. A threshold value processing unit for performing a conversion process is provided, and a sign inversion process is performed for a unit whose absolute value as a result of the 4-point interpolation calculation exceeds the detection limit speed after the 4-point interpolation calculation unit. An ultrasonic diagnostic apparatus comprising a sign inversion processing means. 2. The threshold value processing means can be arbitrarily changed and set according to a site of a subject within a range in which a threshold value for discriminating velocity aliasing is smaller than a detection limit velocity. An ultrasonic diagnostic apparatus characterized by: