JPH04146737A - Ultrasonic diagnostic device - Google Patents

Abstract

PURPOSE:To eliminate the observation difference of the frame image between in an original frame and an interpolation frame by installing a smoothing means which carries out smoothing processing for the present frame, simultaneously with the interpolation operation of an interpolation means which corresponds to the blood flow. CONSTITUTION:An interpolation device 14 applies a variety of interpolation to the blood flow information between the present frame and the preceding frame according to the result of the judgment of a turning-back judging device 13. Further, a smoothing processing device 15 performs smoothing processing for the present frame and preceding frame simultaneously with the interpolation operation of the interpolation device 14. The blood flow information is scanning- converted, together with the B mode information, in a DSC 7A, and outputted on a color monitor 7D through a color processing circuit 7B and a D/A converter 7C, and color-represented. Since, in the color represenation, smoothing processing is carried out simultaneously with interpolation, the black fade-out of the original data is eliminated, and the observation difference of the frame image between the original frame and the color representation can be eliminated.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to an ultrasound diagnostic apparatus that can transmit and receive ultrasound waves and display ultrasound images on a screen, and particularly relates to This invention relates to improvements in technology for obtaining blood flow information within a subject from Doppler information of sound wave echoes and displaying this in two dimensions.

(Prior Art) In the ultrasonic diagnostic method, a B-mode image, an M-mode image, a color Doppler image accompanying the movement of a moving object within a living body using the Doppler effect, etc. are used for diagnosis.

The ultrasonic Doppler method is a method of obtaining and visualizing functional information accompanying the movement of a moving object within a living body, and will be explained below. That is, the ultrasonic Doppler method utilizes the ultrasonic Doppler effect in which when an ultrasonic wave is reflected by a moving object, the frequency of the reflected wave shifts in proportion to the moving speed of the object. Specifically, by transmitting ultrasonic rate pulses to a living body and obtaining the frequency deviation due to the Doppler effect from the phase change of the reflected wave echo, we can obtain motion information of a moving object at the depth position where the echo was obtained. I can do it.

According to this ultrasonic Doppler method, it is possible to know the direction of the flow of blood at a position in the living body and the state of the flow, whether it is turbulent or regular.

Next, a device to which this ultrasonic Doppler method is applied will be explained. First, in order to obtain blood flow information from ultrasound reception signals,
The ultrasonic probe is driven by a transmitting circuit to repeatedly transmit ultrasonic waves in a certain direction a predetermined number of times, and the received signal is detected by a quadrature phase detection circuit to separate Doppler shift signals caused by blood cells and clutter components. We get a signal consisting of This signal is converted into a digital signal, clutter components are removed by a filter, and the Doppler shift signal due to blood flow is frequency analyzed by a high-speed frequency analysis circuit to obtain a color Doppler image in real time. variance of deviation,
Obtain the average intensity of the Doppler shift, etc.

In addition, a color flow mapping image of blood flow velocity is obtained using an autocorrelator built into the frequency analysis circuit, and two-dimensional blood flow information is displayed on a TV monitor. Recently, color Doppler images have also been used to diagnose not only the heart but also areas with slow blood flow, such as abdominal blood vessels and peripheral blood vessels.

(Problems to be Solved by the Invention) However, the conventional ultrasonic diagnostic apparatus for observing two-dimensional blood flow information has the following problems. As mentioned above, in order to obtain two-dimensional blood flow information, it is necessary to transmit and receive ultrasound at multiple rates for one ultrasound raster, and in order to observe blood flow with a slow flow rate, one Ultrasonic rasters must be observed for a long time.

Therefore, it takes a long time to construct one frame, and when used for abdominal blood flow diagnosis, usually about 4 to 10 frames of images are displayed on a TV monitor every second.

However, in order to observe an image that is easy to see even if it is smoothed by humans, at least 30 frames are required per second, and with the above-mentioned number of frames of 4 to 10, the connections between the images are poor and the image is difficult to see. It had become a thing.

Therefore, the applicant of the present application previously proposed a technique as described below.

This previously proposed technology by the applicant writes diagnostic information consisting of tomographic image information and two-dimensional blood flow information alternately into a plurality of frame memories.
The number of frames is increased by interpolating the diagnostic information of the previous frame and the previous frame.

Furthermore, if there is a bend in the blood flow, this is determined and detected, and interpolation is performed in consideration of the bend.

However, after conducting various experiments with the applicant, we found that when displaying a color Doppler image, when frame interpolation is performed, dark spots are less likely to occur in the interpolated frame, whereas black spots are less likely to occur in the original frame. New challenges arose that often arise.

The present invention has been made focusing on this new problem,
The purpose is to provide an ultrasonic diagnostic apparatus that can eliminate the difference in appearance between frame images of original frames and interpolated frames.

[Configuration of the Invention (Means for Solving the Problems) In order to achieve the above object, the present invention obtains tomographic image information based on received signals obtained by transmitting and receiving ultrasonic waves to and from a subject. a processing system, a processing system that obtains two-dimensional blood flow information based on a Doppler shift signal due to blood flow in the received wave signal, and a display control means that obtains a diagnostic information image based on diagnostic information from each of the processing systems; In the ultrasonic diagnostic apparatus, the display control means includes a plurality of frame memories into which the blood flow information input sequentially in frames is written, and a readout means for reading out the blood flow of the current frame and the previous frame from each of the frame memories. and a determining means that compares the blood flow information of the current frame and the previous frame obtained by the reading means and determines whether the blood flow is reversed. It is characterized by comprising an interpolation means that performs interpolation corresponding to blood flow, and a smoothing processing means that performs smoothing processing on the current frame simultaneously with the interpolation operation of the interpolation means.

(Function) With the configuration of the ultrasonic diagnostic apparatus according to the present invention, when the determining means determines that there is a turning of the blood flow based on the blood flow information of the current frame and the previous frame read by the reading means from the frame memory. , the interpolation means performs interpolation corresponding to the blood flow between the current frame and the previous frame, and at the same time the smoothing processing means performs smoothing processing on the current frame and the previous frame, so the interpolation between the original frame (current frame and previous frame) and It is possible to eliminate the difference in appearance between the frame images and the frames.

(Embodiment) FIG. 1 is a block diagram showing the circuit configuration of an ultrasonic diagnostic apparatus according to a first embodiment of the present invention.

The ultrasonic diagnostic apparatus of the first embodiment has a system controller 1 as the control center for the entire system, an ultrasonic probe 2, a transmitting system 3, a receiving system 4, a Bmoto processing system 5, a CFM
It has a (color flow mapping) processing system 6, a display system 7, an operation switch 8, etc.

The ultrasonic probe 2 includes a plurality of piezoelectric transducers arranged in parallel, and these transducers transmit and receive ultrasonic pulses to and from the subject.

The transmission system 3 includes a pulse generator 3A, a transmission delay circuit 3B, and a balsa 3C. In this transmission system 3, a pulse generator 3A generates a rate pulse and sends this rate pulse to a transmission delay circuit 3B. The transmission delay circuit 3B gives a predetermined delay time to each transducer to focus the ultrasonic beam in a predetermined direction to the rate pulse received from the pulse generator 3A, and transmits the delayed rate pulse to the balsa 3.
Send to C. The balsa 3C repeatedly drives each transducer of the ultrasound probe 2 a predetermined number of times based on the delay rate pulse received from the transmission delay circuit 3B.

When the ultrasonic probe 2 is driven to transmit by such a transmission system 3, the ultrasonic pulses transmitted from the ultrasonic probe 1 to a subject (not shown) are generated by Doppler waves caused by blood flow flowing in the subject. The received signal is accompanied by a deviation, and is received by the same transducer of the ultrasound probe 2.

The receiving system 4 to which the received signal obtained by transmitting and receiving the ultrasonic wave is added includes a preamplifier 4A, a receiving delay circuit 4B, and an adder 4C. In this receiving system 4, the preamplifier 4A is
The received signal is amplified to a predetermined level, and the amplified received signal is sent to the reception delay circuit 4B. Reception delay circuit 4
B gives each oscillator a delay time that returns the amplified received signal received from the preamplifier 4A to the original delay time given by the transmission delay circuit 3B. The adder 4C adds and synthesizes the received signals from each vibrator that have passed through the reception delay circuit 4B, and sends the addition and synthesis output to the B-mode processing system 5 and the CFM.
Each is sent to the processing system 6.

The B-mode processing system 5 includes a logarithmic amplifier 5A, an envelope detection circuit 5B, and an A/D converter 5C, and performs the following processing under the control of the system controller 1. That is, in the B-mode processing system 5, the logarithmic amplifier 5A logarithmically amplifies the composite reception signal received from the adder 4C and sends it to the envelope detection circuit 5B. The envelope detection circuit 5B detects the envelope of the composite reception signal received from the logarithmic amplifier 5A, and sends the detection output to the A/D converter 5C. Therefore, the A/D converter 5C converts the detection output from the envelope detection circuit 5B into a digital signal and outputs it to the display system 7 as a tomographic image echo (black and white B mode image).

On the other hand, the CFM processing system 6 includes a phase detection circuit 6A.

A/D converter 6BSMTI processing system 6C, autocorrelator 6D
, an arithmetic unit 6E, and performs the following processing under the control of the system controller 1. That is, the CFM processing system 6
, the phase detection circuit 6A receives the received signal from the adder 4C, performs orthogonal phase detection on the received signal, removes high frequency components using a low-pass filter (not shown), and generates a Doppler shift signal, that is, blood flow. Obtain Doppler detection output for the image. This Doppler detection output includes, in addition to blood flow information, unnecessary reflected signals (clutter components) from slow-moving objects such as the wall of the heart. Therefore, the Doppler detection outputs are converted into digital signals by the A/D converter 6B and passed through the MTI filter 6C. Here, MT
I is the technology used in radar, Moving
-Target-Indicator is a method of detecting only moving targets using the Doppler effect.

Therefore, the MTI filter 6C detects the movement of blood flow based on the phase change between the same pixels in rate pulses that are repeatedly transmitted a predetermined number of times, and removes clutter.

In order to frequency analyze the signal from which this clutter has been removed, M
There is an autocorrelator 6D at the next stage of the TI filter 6c, and this autocorrelator 6D has a functional configuration that performs two-dimensional multi-point analysis in real time, and requires fewer operations than the one using the FFT method. It can also be done.

The calculation section 6E at the next stage of the autocorrelator 6D has a functional configuration including an average speed calculation section, a variance calculation section, and a power calculation section. And in this autocorrelator 6D,
The average velocity calculation unit calculates the average Doppler shift frequency fd,
The dispersion calculation unit calculates the variance σ2, and the power calculation unit calculates the total power TP. Note that the total power TP is proportional to the intensity of scattered echoes from the blood flow, but the MTI filter 6
Echoes from moving objects corresponding to frequencies below the cutoff frequency of C are removed. The blood flow information obtained in this way is output to the display system 7.

As described above, the display system 7 to which the outputs of the B-mode processing system 5 and the CFM processing system 6 are added includes a DSC (digital scan converter) 7A, a color processing section 7B, a D/A converter 7C, and a color monitor 7D. ing. This display system 7
In this case, the DSC 7A has a block configuration as shown in the detailed explanatory diagram of FIG. It consists of a smoothing processor 15.

The three frame memories 9, 10, and 11 are sequentially input in frame units as shown in FIG. 3 under the control of the system controller 1 with control signals.

Note that FIG. 3 is an example of double interpolation that doubles the number of display frames. Write the above B-mode image data and Doppler data.

The output sides of these frame memories 9 to 11 are connected to the input side of MUX 12, respectively.

The MUX 12 receives blood flow information F from the three frame memories 9 to 11 for the current frame and the previous frame.

Read F2. For example, data W3 is stored in frame memory 9.
When writing frame memory 10.11
Read data R,,R2 from M
Output to UX12. Similarly, in the next frame, when writing data to be sequentially input to the frame memory 10,
Read data R2 and R3 from frame memory 11.9. Similarly, data is sequentially written into one frame memory and data from the other two are read out. Therefore, MUX
The outputs F, , F2 of 12 have the relationship shown in FIG.

The loop determination unit 13 receives data F from the MUX 12,
, F2 are compared, and if the absolute value of the difference between the data F, , F2 is larger than a certain threshold level and the signs are different, it is determined that the loop is due to blood flow, and information to instruct the loop is sent. Interpolator 14 and smoothing processor 15
Output to.

The determination operation of the aliasing determiner 13 will be specifically explained as follows. For example, as shown in FIG. 4, with respect to the direction of blood flow in a blood vessel, a flow approaching the ultrasound probe 2 is defined as a forward direction, and a flow moving away from the ultrasound probe 2 is defined as a reverse direction. As shown in Fig. 5, the median value 32 of the 6-bit flow velocity data (0 to 63) is set to 0, and the flow velocity is set to 0 to 32.
is the flow velocity in the reverse direction (front thread), 32-63 is the flow velocity in the forward direction (
When defined as red (reddish), the turning of the blood flow will be explained below with reference to FIG.

In Figure 6, if no folding occurs, O
The interpolated data of data F, . . . F2 entered in ~63 becomes data FI2. However, when turning occurs, the interpolation data becomes the position of FHo because it moves to F2 - where F2 becomes (F2+64), for example. However, since this value is greater than or equal to 64, it becomes the value of the lower 6 bits, that is, the value FL of (FH64).

Note that the appropriate threshold level for the aliasing determiner 13 used here is a purity of 378 for the overall value, and 24 in the case of 64 data.

The interpolator 14 performs various interpolations on the blood flow information between the current frame and the previous frame according to the determination result of the aliasing determiner 13. Further, the smoothing processor 15 performs smoothing processing on the current frame and the previous frame simultaneously with the interpolation operation of the interpolator 14.

Due to the simultaneous processing operation by the interpolator 14 and the smoothing processor 15, when the blur ratio α is α-374, the characteristics of the smoothing function h(t) with respect to the time axis t are as shown by the dotted line in FIG. It becomes the enveloping property of In addition,
When only interpolation is performed by the interpolator 14, the envelope characteristic will be as shown by the dashed line in the figure.

As a result, based on the data R7 and R2 read from the interpolator 14, for example, the corrected frame (RI+R2)/
2, the smoothing processor 15 smoothes the original data itself as (1-α)R++αR2, so the output data of the MUX 16 has the relationship shown in FIGS. 3 and 8.

The output data of this MUX 16 is sent to the color processing circuit 7B. In this color processing circuit 7B, ■
In the case of −62 display, the flow approaching the ultrasonic probe 2 is converted to red color, and the flow moving away from the ultrasonic probe 2 is converted to the front thread.

Also, the size of the average speed is expressed by the difference in brightness,
Velocity dispersion is expressed by hue.

In this way, blood flow information is transmitted to DSC7A along with B-mode image information.
The color processing circuit 7B and the D/A
The image is outputted to a color monitor 7D via a converter 7C, and is expressed in color.

Returning to this color system, smoothing processing is performed at the same time as interpolation as described above in the DSC7A, so black spots in the original data are removed and the difference in appearance between the original frame and the frame image is eliminated. was completed.

Next, a second embodiment of the present invention will be described. This second embodiment includes the aliasing determination device in the first embodiment described above,
The functions of the interpolator smoothing processor are shown in Figure 9.
This ROM 17 is applied to the DSC 7 described in FIGS. 1 and 2. i.e. ROM 1
6a inputs flow velocity data of two adjacent frames consisting of 6 bits, and generates four interpolated data as shown below in response to a switching signal consisting of 2 bits.

(1) First, as shown in Fig. 10, Fl>F2°Fl
-F2 l >v+h (V+h is swash*-
■When the switching signal is 00, (1+2α)F/4+ (
The lower 6 bits of data FL of 3-2α)(F2 +64)/4 are output.

■When the switching signal is 01, fF++(F2+64)l
The lower 6 bits of data FL of /2 are output.

■When the switching signal is 10, (3-2α)F/4-)-
The lower 6 bits of data FL of (1+2α)(F2+64)/4 are output.

■When the switching signal is 11, (1-α)F++α(F2
+64) lower 6 bits of data F.

Output.

(2) Next, as shown in Fig. 11, Fl<F2°Fl −
In the case of F2 1 > V+h, ■When the switching signal is 00, (1+2α)(F s + 64 ) / 4
+ (3-2α) F2 /4 lower 6 bit data F
Output L.

■When the switching signal is 01, ((F+ +64)+F2
Outputs 1/2 lower 6-bit data FL.

■When the switching signal is 10, (3-2α)(F + +
64)/4+(1+2α)F2/4 lower 6 bit data FL is output.

■When the switching signal is 11, (1-α) (F+64
)+αF2 lower 6 bits of data FL are output.

(3) In cases other than (1) and (2), that is, when no turning occurs between Fl and F2, ■When the switching signal is 00, (1+2α)F/4+ (3-2α ) F2 /
The lower 6-bit data FL of 4 is output.

(2) When the switching signal is 01, the lower 6 bits of data FL of (Fl +F2)/2 are output.

■When the switching signal is 10, (3-2α)F/4+ (
1+2α) The lower 6 bits of data FL of F2/4 are output.

(2) When the switching signal is 11, the lower 6 bits of data FL of (1-α)F++αF2 are output.

By subjecting the data of two frames to weighted average processing in this manner, interpolation can be performed four times in accordance with aliasing, and at the same time, the original data can be smoothed.

As a result, the number of frames is four times as large as the conventional number of frames, making the ultrasonic image smoother and easier to see. Furthermore, since turning of the blood flow is determined based on the switching signal, an appropriate interpolation frame can be generated depending on the turning.

[Effects of the Invention] As explained above, according to the present invention, tomographic image information and
Diagnostic information consisting of dimensional blood flow information is written alternately into multiple frame memories, interpolation is performed between the diagnostic information of the current frame and the diagnostic information of the previous frame, and at the same time smoothing is performed on the current frame and the previous frame themselves. This has the effect of increasing the number of frames and obtaining smooth ultrasonic images in which black spots in blood flow are removed.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the circuit configuration of an ultrasonic diagnostic apparatus according to a first embodiment of the present invention, and FIG. 2 is a detailed explanation of a DSC that constitutes a main part of the first embodiment of the present invention. Figure 3 is a time chart showing the output status of each part in the DSC, Figure 4 is a diagram showing forward flow and reverse flow of blood in blood vessels, Figure 5 is a diagram showing the allocation of flow velocity data for forward flow and reverse flow, Figure 6 is a diagram to explain folding due to blood flow, Figure 7 is a diagram showing smoothing function characteristics, Figure 8 is a diagram showing changes in frame images when smoothing is performed, and Figures 9 to 11. The figure is a diagram for explaining a second embodiment of the present invention. 1... System controller 2... Ultrasonic probe 3... Transmission system 4... Receiving system 5... B mode processing system 6... CFM processing system 7...
・Display system 8...Operation switches 9 to 11...Frame memory 12...MUX13...Return judgment device
14... Interpolator 15... Smoothing processor 16
...MUX17...ROM Figure 7

Claims (1)

[Claims] (1) A processing system that obtains tomographic image information based on a received signal obtained by transmitting and receiving ultrasound to and from a subject, and a two-dimensional blood flow based on a Doppler shift signal due to blood flow in the received signal. In an ultrasonic diagnostic apparatus having a processing system for obtaining information and a display control means for obtaining a diagnostic information image based on the diagnostic information from each of the processing systems, the display control means is configured to display the blood, which is sequentially input in frame units. A plurality of frame memories into which flow information is written, a reading means for reading out the blood flow of the current frame and the previous frame from each frame memory, and a reading means that compares the blood flow information of the current frame and the previous frame obtained by the reading means and calculates the blood flow. a determining means for determining aliasing; an interpolating means for performing interpolation corresponding to the blood flow between the current frame and the previous frame when a determination result is generated in the determining means; An ultrasonic diagnostic apparatus characterized by comprising a smoothing process means for performing a smoothing process on the image.