JPH07265309A - Ultrasonic diagnostic apparatus - Google Patents

Abstract

PURPOSE:To enable the arbitrary zero shift of a blood flow image by setting different color data on the basis of a blood flow velocity direction with respect to a blood flow velocity signal within a blood flow velocity measuring range and setting the same color data as the color data immediately before exceeding the blood flow velocity measuring range with respect to the blood flow velocity signal exceeding the blood flow velocity measuring range. CONSTITUTION:A blood flow imaging processing part 31 is constituted of an A/D converter 12, a digital filter 13 removing a clutter component, a correlation part 14 calculating correlation and an operation part 15 executing operation calculating blood flow velocity, dispersion and power with respect to the output signal of the correlation part 14. The operation part 15 has adders 25a, 25b adding two kinds of signals taken in correlation by the correlation part 14 to send out an imaginary number part signal and a real number part signal, a divider 26 calculating the quotient of both signals, a flow velocity operation circuit 27 taking in the flow velocity signal and calculating a flow velocity signal with respect to the quotient and a zero shift processing circuit 28 executing the zero shift operation based on the zero shift quantity signal from an input means.

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 having a display image zero shift function.

[0002]

2. Description of the Related Art For example, when an ultrasonic diagnostic apparatus having a blood flow imaging function is used to display the direction and speed of blood flow in a subject in color, a blood flow image exceeding a certain speed due to the functional limitation of this apparatus. May be displayed in a color different from the color that should be originally displayed.

In such a case, no conventional blood flow imaging ultrasonic diagnostic apparatus has a function such as zero shift of a display image.

By the way, in the ultrasonic diagnostic apparatus adopting the Doppler method for displaying the frequency analysis result at a certain point using FFT (Fast Fourier Transform),
There is a technique called zero shift (zero level shift) or baseline shift.

The outline of the zero shift function will be described with reference to FIGS. 7 and 8. 7 and 8, the horizontal axis represents time, the vertical axis represents flow velocity, and the upper limit of the measurement range is + M.
AX, the lower limit is shown by -MAX. And this +
The range from MAX to -MAX is the display area.

When the blood flow velocity, which changes with the passage of time, exceeds the upper limit (+ MAX) of the measurement range, the exceeded portion (the portion indicated by the dotted line) is separated into display regions in the opposite direction, as shown in FIG. Is displayed. Such a phenomenon is called a folding phenomenon.

When this folding back phenomenon occurs, there is a problem in that it is difficult for the operator to see the displayed image, and it is confused with backflow.

Therefore, as shown in FIG. 8, if the zero line on the vertical axis is shifted in the reverse flow direction by, for example, ¼ of the display area, so that the maximum value of the flow velocity becomes equal to or less than the upper limit (+ MAX),
Images can be obtained that represent continuous changes in flow velocity.

In an actual electronic circuit, the address of the RAM (random access memory) at the output stage corresponds to the flow velocity, and when writing data, the address is shifted by the zero shift amount, or when reading, the address is shifted by the zero shift amount. It is also read out by shifting.

[0010]

Even in the blood flow imaging ultrasonic diagnostic apparatus, since the Doppler signal is sampled in synchronization with the ultrasonic rate as in the FFT Doppler method described above, there is an upper limit to the measurable flow velocity, A folding phenomenon occurs in the flow velocity portion exceeding the upper limit. The folding phenomenon in this case appears as a change in the color of the display image. That is,
If the forward flow is expressed in red and the reverse flow is expressed in blue, the folded portion changes from red to blue.

For example, as shown in FIG. 9, a region of a high flow velocity portion, which should be originally displayed in red, is folded and displayed in a blue portion corresponding to a low flow velocity portion. The operator does not mistakenly think that such a turned-back portion is a backflow, but it is easier to see if it is displayed in red in comparison with blood flow.

Further, since the direction of the blood flow cannot be discriminated by the conventional Doppler method as in the blood flow imaging, an ultrasonic beam is made incident from various directions to search for a place where the fastest flow velocity can be obtained.

However, since the direction in which the ultrasonic beam can be incident cannot be set arbitrarily depending on the shape of the ultrasonic probe and the positional relationship of the living organs, the maximum flow velocity error often occurs depending on the incident angle. Further, it was necessary to measure at which position the maximum flow velocity was obtained while adjusting the sample volume position, which was very complicated.

The present invention has been made in view of the above circumstances. The blood flow imaging image can be arbitrarily zero-shifted, and the blood flow imaging image and the Doppler signal image can be easily compared and the maximum flow velocity portion can be easily determined. It is an object of the present invention to provide an ultrasonic diagnostic apparatus.

[0015]

In order to achieve the above object, an outline of the present invention is to provide an ultrasonic wave transmitting / receiving means for transmitting / receiving an ultrasonic wave to / from an object, and an ultrasonic wave transmitting / receiving means Blood flow velocity measuring means for measuring the blood flow velocity based on the reflected component of the ultrasonic wave from the blood flow of the blood flow velocity measuring range within the blood flow velocity measuring range obtained by the blood flow velocity measuring means Converts the blood flow velocity signal into a display information signal in which different color information is set based on the blood flow direction component, and converts the blood flow velocity signal to the blood flow velocity signal when the blood flow velocity signal exceeds the blood flow velocity measurement range. Display information setting means for converting into a display information signal set to the same color information as the blood flow velocity signal immediately before exceeding the rapid measurement range, and a display for displaying a blood flow image in color based on the display information signal from the display information setting means. And means.

[0016]

According to the above configuration, different color information is set for the blood flow velocity signal within the blood flow velocity measurement range based on the blood flow velocity direction, and the blood flow velocity signal exceeding the blood flow velocity measurement range is set. Sets the same color information as the color information immediately before passing, which facilitates comparison between the blood flow imaging image and the Doppler signal image and the determination of the maximum flow velocity portion.

[0017]

The principle of the present invention and examples for carrying out this principle will be described below in detail.

First, the principle of the present invention will be described. Generally, the method shown in FIG. 5 is used as a method of expressing a blood flow imaging image. That is, the hue spread (dispersion) is represented in the horizontal direction with reference to the 0-point line, and the flow velocity of blood flow is represented as upward flow and forward flow is provided as downward flow in the vertical axis direction, which is represented by a change in luminance. The direction of blood flow is represented by a change in hue.

FIG. 6 shows such an expression method in comparison with the expression method of the Doppler method. Here, the luminance corresponding to the flow velocity has an upper limit depending on the standard and performance of the television monitor.

Also, in the figure, the point means 1/8 shift.

If the maximum flow velocity that can be detected in both the forward and reverse directions of the flow velocity is set to the maximum brightness without the zero shift, the maximum detectable flow velocity range is apparently widened when the zero shift is performed. The maximum flow velocity must be set to maximum brightness. If this operation is not performed, all the blood flow in the flow velocity range expanded by the zero shift is expressed with the same brightness as the brightness of the initially detectable maximum flow speed, and flow speed discrimination based on the brightness becomes impossible.

Further, the number of gradations from the maximum brightness to the minimum brightness is fixed (for example, 256 gradations) for the sake of technical simplicity, and one gradation is obtained when the maximum detectable flow velocity increases due to zero shift. The flow velocity range expressed by is widened. This means that when the flow velocity signal is converted into the luminance signal, it is compressed when compared with when there is no zero shift.

From the above, when the zero shift is performed, the color representing the flow velocity may be changed according to the shift amount (the direction is also included by + and-), and according to the shift amount. A compression operation may be added when converting the flow velocity signal into the luminance signal.

Next, an embodiment of the present invention for realizing the above principle will be described with reference to FIGS.

In the apparatus of the embodiment shown in FIG. 1, the transducer 2 is driven by the drive circuit 1 and sends ultrasonic pulses to a subject (not shown).

The reflected echo from the subject is received by the transducer 2, converted into an ultrasonic echo signal (electrical signal), amplified by a receiver 3 including a delay circuit, and sent to a detection circuit 7 and a LOG (logarithmic) amplifier 4. To be

The LOG amplifier 4 and the A / D converter 5 for converting its output signal into a digital signal constitute a tomographic image display processing section 30.

The ultrasonic echo signal detected by the detection circuit 7 is sent to the blood flow imaging processing unit 31 and the ultrasonic Doppler processing unit 32.

The blood flow imaging processing section 31 is an A / D converter 1 for converting an ultrasonic echo signal into a digital signal.
2, a digital filter 13 that removes a clutter component from the output signal from the A / D converter 12, a correlation unit 14 that takes in the output signal of the digital filter 13 and obtains its correlation, and a blood flow with respect to the output signal of the correlation unit 14. The calculation unit 15 executes a calculation for obtaining the velocity v, the variance σ, and the power p.

The ultrasonic Doppler processing unit 32 has a sample hold circuit 8 for sampling the ultrasonic echo signals from the detection circuit 7, and a sample hold circuit 8.
Bandpass filter 9 that removes unnecessary frequency components from the output signal of, the amplifier 10 that amplifies the output signal of this bandpass filter 9, and the output signal of the amplifier 10 is taken and frequency analysis is performed on this and the Doppler signal is transmitted. FFT to
(High-speed Fourier transform) circuit 11.

The outputs of the A / D converter 5, the arithmetic unit 15, and the FFT circuit 11 are all taken into the digital scan converter 6 in a predetermined order, and further, after specific color data is assigned by the color processor 16,
It is sent to the D / A converter 17 and converted into an analog signal. Then, this analog signal is sent to the color television 18 and is superimposed and displayed as a tomographic image, a blood flow imaging image, and a Doppler signal image of the subject.

The analog signal is also sent to the video tape recorder 20 via the encoder 19 for converting the RGB television signal into a composite television signal, whereby the image displayed on the color television 18 is recorded. It

In FIG. 1, reference numeral 21 is a controller for controlling the digital scan converter 6 and the color processor 16.

Now, the arithmetic unit 15 will be described in more detail. As shown in FIG. 2, the calculation unit 15 has two types of signals (xi yi + 1-xi + 1y) correlated by the correlation unit 14.
i), (xi xi + 1 + yi yi + 1), respectively, and the imaginary part signal Im {C (τ)} and the real part signal Re {C
(Τ)} for sending the first and second adders 25a and 25b
And the imaginary part signal Im {C (τ)} and the real part signal R
quotient Im {C (τ)} / Re {C of e {C (τ)}
(Τ)}, a flow velocity calculation circuit 27 that calculates the flow velocity signal fd by executing the calculation of the following equation (1) for this quotient, and a flow velocity signal fd which is input from an input means (not shown). Zero shift amount signal (0, 1 in the blue direction
/ 8, 2/8, 3/8, 4/8, 1/8, 2 / toward the red
(8, 3/8, 4/8) based zero-shift operation circuit for transmitting zero-shift flow velocity signal f0 by executing zero-shift operation (eg RO).
M (read-on memory) 28.

Fd = fr / 2πtan ^-1 [Im {C (τ)} / Re {C (τ)}] (1) The zero shift processing circuit 28 is a 4-bit zero shift amount signal as shown in FIG. An 8-bit flow velocity signal fd is input and an 8-bit zero-shift flow velocity signal fo is output.

Further, in each address 000 to 8FF of the zero shift processing circuit 28, as shown in FIGS. 4 (a) to 4 (g), 256 gradations of 7 kinds of red or blue are provided, each having 256 gradations. It is assigned in advance.

That is, in the addresses 000 to 07F of the zero shift processing circuit 28, as shown in FIG.
The gradations to the 128th gradation, and the addresses 080 to OFF are sequentially assigned the blue 1st gradation to the blue 128th gradation, respectively.

The address 10 of the zero shift processing circuit 28
0 to 17F and addresses 1FF to 1EO sequentially show the first red gradation to the red 128th gradation as shown in FIG.
The 80th to 1DF are sequentially assigned the first blue gradation to the 77th blue gradation. The following addresses 200-2F
F, ..., 800 to 8FF are also shown in FIG.
Each gradation shown in (c) to FIG. 4 (g) is assigned. Where (a) is not zero-shifted, (b)
(C) and (d) are blue direction 1/8 2/8 4/8, (e)
(F) and (g) correspond to 1/8 2/8 4/8 shift in the red direction.

Next, the operation of the apparatus having the above configuration will be described focusing on the operation of the arithmetic unit 15.

It is assumed that the zero shift processing circuit 28 receives the flow velocity signal fd corresponding to the maximum flow velocity side 192 gradations from the flow velocity calculating circuit 27. At this time, when the operator sends the zero shift amount signal (0) from the input means to the zero shift processing circuit 28, zero shift is not performed on the flow velocity signal fd, and the gradation pattern for this flow velocity signal fd is shown in FIG. The address 000 to OFF shown is selected, and as a result, the maximum flow velocity side 64 as shown in the left column of FIG. 6 is selected.
The zero-shift flow velocity signal fO accompanied by the gradation return phenomenon is sent to the digital scan converter 6.

On the other hand, when the operator sends (2/8 in the blue direction) as a zero shift amount signal from the input means to the zero shift processing circuit 28, the gradation pattern shown in FIG. 4C is selected in the zero shift processing circuit 28 in this case. Then, as shown in the right column of FIG. 6, a zero-shift flow velocity signal fo'which is shifted by 2/8 in the blue direction and is not accompanied by the folding phenomenon is sent to the digital scan converter 6. That is, in this case, 192 gradations are addresses 200 to 27F and addresses 2FF to 2F.
It is sent out as a zero-shift flow velocity signal fO 'converted from the red-side first gradation to the 128th gradation, which is assigned to 128 addresses up to CO.

Similarly, when the zero shift amount signal (blue ⅛) is sent, the gradation pattern of FIG. 4 (b) is given the zero shift amount signal (blue ⅛). In the case where the gradation pattern of FIG. 4E is sent as a zero shift amount signal (red direction 1/8), the gradation pattern of FIG. 4E is processed as a zero shift amount signal (red direction 2/8). 4) is transmitted, the gradation pattern of FIG. 4F is transmitted, and when the zero shift amount signal (red direction 4/8) is transmitted, the gradation pattern of FIG.
The gradation patterns (g) are selected, and the zero-shift flow velocity signals f0 corresponding to them are sent to the digital scan converter 6.

The zero-shift flow velocity signal fO thus obtained is read by the digital scan converter 6, and the same processing as that described above is performed and displayed on the color television 18 and by the video tape recorder 20. Will be recorded.

In this case, the digital scan converter 6 is controlled by the controller 21, and the FFT circuit 11
The Doppler signal is also read and sent to the color processor 16. At this time, by shifting the order of reading the Doppler signal in accordance with the zero shift amount of the zero shift shift flow signal fO, the zero shift flow signal on the color television 18 is read. The image based on f0 and the Doppler signal image can be displayed in association with each other.

Separately from this, the zero shift processing circuit 2
The controller 2 controls the digital scan converter 6 to read the Doppler signal from the FFT circuit 11 while appropriately changing the reading order independently of the amount of zero shift in 8.
You may make it control by 1.

The present invention is not limited to the above-mentioned embodiments, but various modifications can be made within the scope of the invention.

For example, in the above-mentioned embodiment, the case where the zero shift processing circuit 28 of the arithmetic unit 15 performs the zero shift processing according to the flow velocity of the blood flow has been described. However, the flow velocity signal fd is read by the digital scan converter which is the data reading unit. After that, the zero-shift process may be performed on the flow velocity signal fd.

In the above-described embodiment, the case where the flow velocity calculation circuit 27 of the calculation unit 15 and the zero shift processing circuit 28 are separately configured has been described, but the zero shift processing circuit 2 is described.
Since the ROM 8 can be configured by using a ROM, it can be similarly implemented by using a single ROM that serves both of them.

Further, the contents of the gradation pattern of the zero shift processing circuit 28 in the above-mentioned embodiment are shown in FIG.
Many modifications other than those shown in FIGS. 4A to 4G are possible.

[0050]

According to the present invention described in detail above, the blood flow imaging image can be zero-shifted in accordance with the blood flow velocity, can be compared with the Doppler signal image, and the maximum flow velocity portion can be clearly discriminated. An ultrasonic diagnostic apparatus can be provided.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing details of a calculation unit of the device.

FIG. 3 is an explanatory diagram showing input and output addresses of a zero shift processing circuit in an arithmetic unit.

FIG. 4 is an explanatory diagram showing various gradation patterns stored in respective addresses of the zero shift processing circuit.

FIG. 5 is an explanatory diagram showing a method of expressing a blood flow imaging image.

FIG. 6 is an explanatory view showing a blood flow imaging image and an expression method based on the Doppler method for comparison.

FIG. 7 is an explanatory diagram showing a state in which a turnback phenomenon occurs in the blood flow velocity display by the Doppler method.

8 is an explanatory diagram showing a state where zero shift is performed on the blood flow velocity display shown in FIG. 7.

FIG. 9 is an explanatory diagram showing a state in which a blood flow imaging image has a folding phenomenon.

[Explanation of symbols]

 6 Digital Scan Converter 11 FFT Circuit 15 Operation Unit 31 Blood Flow Imaging Processing Unit 32 Ultrasonic Doppler Processing Unit 28 Zero Shift Processing Circuit

Claims (4)

[Claims] 1. An ultrasonic wave transmitting / receiving means for transmitting / receiving ultrasonic waves to / from a subject, and a blood flow velocity is measured based on a reflected component of ultrasonic waves from a blood flow in the subject obtained by the ultrasonic wave transmitting / receiving means. For the blood flow velocity measuring means and the blood flow velocity signal within the blood flow velocity measuring range obtained by the blood flow velocity measuring means, different color information is set for the blood flow velocity signal based on the blood flow direction component. Converted to the displayed information signal and set the same color information as the blood flow velocity signal immediately before exceeding the blood flow velocity measurement range for the blood flow velocity signal when the blood flow velocity measurement range is exceeded. An ultrasonic diagnostic apparatus comprising: display information setting means for converting the display information signal into a display information signal; and display means for displaying a blood flow image in color based on the display information signal from the display information setting means. 2. The display information setting means is a blood flow velocity exceeding the blood flow velocity measuring range for a blood flow velocity signal exceeding the blood flow velocity measuring range obtained by the blood flow velocity measuring means. The smaller the absolute value of the signal, the greater the blood flow velocity based on the blood flow direction component, and the blood flow velocity signal is converted into a display information signal in which luminance information corresponding to the blood flow velocity is set. The ultrasonic diagnostic apparatus according to claim 1. 3. The display means displays the color and brightness setting states set by the display information setting means together with the blood flow image in a display form corresponding to the blood flow velocity. The ultrasonic diagnostic apparatus described. 4. The display information setting changing means for changing the setting condition of the color information or the brightness information set by the display information setting means is provided. Sound wave diagnostic equipment.