JPH03289947A - Ultrasonic diagnostic device - Google Patents

Abstract

PURPOSE:To provide an ultrasonic picture which is smooth and easy to see by alternately writing fault information and diagnosing information, consisting of blood flow information, in a frame memory and interpolating diagnosing information of a present frame and diagnosing information of a preceding frame. CONSTITUTION:In a DSC 6A wherein both blood flow information and B-mode picture information are inputted, frame memories 11-13 write orderly B-mode picture data and Doppler data input at a frame unit under control by a controller 7B. An MUX 14 reads blood flow information F1 and F2 of a present frame and one frame before from a plurality of the frame memories 11-13, and data is outputted to an MUX 17, a folding decider 15, and an interpolator 16. The folding decider 15 compares data outputs F1 and F2 with each other. When an absolute value of a difference therebetween exceeds some threshold level and a code is different, it is decided that back to back due to a blood flow occurs, and a result is outputted to an interpolator 16. The interpolator 16 effects interpolation in consideration of folding when the folding occurs, and formation of a proper interpolation frame causes a picture to be easily seen.

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention (Field of Industrial Application) The present invention particularly relates to ultrasonic diagnosis in which blood flow information within a subject is determined from Doppler information of ultrasound echoes and is displayed two-dimensionally. Regarding equipment.

(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 for a human to observe a smooth and easy-to-read image, at least 30 frames are required per second, and with the number of frames of 4 to 10 as mentioned above, the connections between the images are poor and the images are difficult to see. It became.

Therefore, an object of the present invention is to provide an ultrasonic diagnostic apparatus that obtains smooth and easy-to-see ultrasonic images.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems and achieve the objects, the present invention takes the following measures. The present invention obtains a tomographic image based on a received signal obtained by transmitting and receiving ultrasonic waves to and from a subject, and
In an ultrasonic diagnostic apparatus that detects a Doppler shift signal due to blood flow, detects the Doppler signal with a filter to obtain two-dimensional blood flow information, and displays this diagnostic information via a storage means, the storage means sequentially a plurality of frame memories into which the diagnostic information inputted in frame units is written; means for reading diagnostic information of the current frame and previous frame from these frame memories; and a means for reading diagnostic information of the current frame and previous frame read by the means. The present invention is characterized by comprising an interpolation means for performing interpolation.

Further, the storage means includes a plurality of frame memories into which the blood flow information input sequentially in frame units is written, means for reading out the blood flow information of the current frame and the previous frame from these frame memories, and the current frame and the blood flow information read out by the means. a determining means for comparing the blood flow information of the previous frame and determining whether the blood flow turns back; and, depending on the result of the determining means, performing various interpolations on the blood flow information of the current frame and the previous frame read by the reading means. Features (effects) characterized by the provision of an interpolation means for performing the following effects. Diagnostic information consisting of tomographic image information and two-dimensional blood flow information is written alternately into multiple frame memories, and the diagnostic information of the current frame and the diagnostic information of the previous frame are interpolated. diagnostic information can be generated. This allows the number of frames to be increased several times over the conventional number of frames, making the ultrasound image smoother and easier to view.

Further, since the aliasing of the blood flow is determined, if there is aliasing, interpolation is performed taking the aliasing into consideration when generating an interpolated frame, so that an appropriate interpolated frame can be generated. In general, whether the interpolated image is correct or not (
In other words, as for whether the interpolated image is the same as the image actually sampled at that time, it is known that if the sampling theorem is satisfied when the original signal is sampled, then the interpolated image is correct.

(Example) Hereinafter, specific examples of the present invention will be described.

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

The ultrasonic diagnostic device includes an ultrasonic probe 1. The transmission system 2 includes a pulse generator 2A, a transmission delay circuit 2B, and a pulser C. The reception system 3 includes a preamplifier 3A and a reception delay circuit 3. Adder 3
It has C. The device also includes a logarithmic amplifier as a B-mode processing system 4, an envelope detection circuit 4B, an A/D (analog-to-digital conversion) 4C, a phase detection circuit 5A, an A/D 5B as a CFM (color flow mapping) processing system 5, MT
It has an I filter 5C, an autocorrelator 5D, and an arithmetic unit 5E. Furthermore, the apparatus includes a DSC (digital φ scan e-converter) 6A as a display system 6, color processing sections 6B, D
/A6C, color monitor 6D.

The control system 7 includes an operation 5W7A and a controller 7B.

The ultrasonic probe 1 includes a plurality of piezoelectric transducers, and these transducers transmit and receive ultrasonic pulses to and from a subject.

The pulse generator 2A generates a rate pulse and outputs this rate pulse to the transmission delay circuit 2B.

The transmission delay circuit 2B gives a predetermined delay time to each transducer to converge the ultrasonic beam in a predetermined direction to the rate pulse inputted from the pulse generator 2A, and converts the delayed rate pulse into a predetermined delay time. Output to pulser 20. The pulser 2C repeatedly drives each transducer of the ultrasound probe 1 a predetermined number of times based on the delayed rate pulse.

That is, when the ultrasound probe 1 is driven to transmit by the pulser 20, the ultrasound pulses transmitted from the ultrasound probe 1 to a living body (not shown) are subject to Doppler shift due to blood flow flowing inside the living body. The received signal is received by the same transducer of the ultrasonic probe 1.

The preamplifier 3A amplifies the received signal to a predetermined level and outputs it to the reception delay circuit 3B. The reception delay circuit 3B gives the reception signal from each vibrator a delay time that restores the original delay time given by the transmission delay circuit 2B.

Then, the adder 3C adds and synthesizes each received signal from each vibrator. Further, the output of the adder 3C is input to the B mode processing system 4 and the CFM processing system 5.

First, the B-mode processing system 4 performs the following processing under the control of the controller 7B. The logarithmic amplifier 4A is
Logarithmically amplifying the received signal output from the adder 3C,
It is output to the envelope detection circuit 4B. The envelope detection circuit 4B detects the envelope of the signal from the logarithmic amplifier 4A.

After that, the detection output from the envelope line detection circuit 4B is
/D4C converts it into a digital signal and outputs it to DSC6A as a tomographic image echo (black and white B mode image).

On the other hand, the CFM processing system 5 performs the following processing under the control of the controller 7B. The phase detection circuit 5A is
A received signal based on a rate pulse repeatedly transmitted a predetermined number of times is input from the adder 3C.

The phase detection circuit 5A performs quadrature phase detection on the received signal,
High frequency components are removed by a low-pass filter (not shown) to obtain a Doppler shift signal, that is, a Doppler detection output for a blood flow 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.

Further, the Doppler detection output is converted into a digital signal by the A/D 5B, and then passed through the MTI filter 5C.
Enter.

MTI is a technology used in radar.Movin
G Target Indicator is a method of detecting only moving targets using the Doppler effect. Therefore, the MTI filter 5C detects the movement of blood flow based on the phase change between the same vixels in the N rate pulses, and removes clutter.

Next, an autocorrelator 5D is used to perform frequency analysis on the signal from which clutter has been removed. This autocorrelator 5D is a type of frequency analysis method, is used because it is necessary to perform two-dimensional multi-point frequency analysis in real time, and has the advantage that it requires fewer calculations than the FFT method.

The calculation section 5E has an average speed calculation section, two distributed calculation sections, and a power calculation section inside. The average velocity calculation unit calculates the average Doppler shift frequency fd, the dispersion calculation unit calculates the variance σ2,
The power calculation unit calculates the total power TP.

This total power TP is proportional to the intensity of echoes scattered from the blood flow, but echoes from moving objects corresponding to a frequency below the cutoff frequency of the MTI filter 5C are excluded.

Furthermore, the blood flow information from the arithmetic unit 5E is input to the DSC 6A, and is converted into color information by the color processing circuit 6B. That is, in the case of V-σ2 display by the color processing circuit 6B, the flow approaching the ultrasonic probe 1 is converted into a red color, and the flow away from the probe 1 is converted into a front thread. Further, the magnitude of the average velocity is expressed by a difference in brightness, and the velocity dispersion is expressed by hue.

The blood flow information is thus scan-converted along with the B-mode image information in the DSC 6A, and the color processing circuit and D/A 6
The image is output to the color monitor 6C via C, and is expressed in color.

Next, the features of this embodiment will be explained. Second
The figure is a diagram showing details of the DSC 6A. FIG. 3 is a diagram for explaining writing or reading of data into or from the frame memories 11 to 13 and data interpolation, and FIG. 4 is a diagram for explaining data interpolation between frames.

In FIG. 2, DSC6A has three frame memories 1
1-13. Multiplexer 14.17 as control means
(hereinafter referred to as MUX) 1. Turning judgment device as a judgment means 15. It consists of an interpolator 16 as interpolation means.

The three frame memories 11, 12, and 13 write the B-mode image data and Doppler data that are sequentially input in frame units as shown in FIG. 3 under the control of a control signal s1 input from the controller 7B. It's crowded. The output sides of these frame memories 11 to 13 are connected to the input side of MUX 14, respectively.

The MUX 14 reads blood flow information F, F2 of the current frame and one frame before from the plurality of frame memories 11 to 13. For example, when data W3 is written to the frame memory 11, data R1 and R2 are read from the frame memory 1213, and these data are sent to MUX1.
7. Turning judger 15. Output to interpolator 16. Similarly, in the next frame, when writing data to be sequentially input to the frame memory 12, the frame memory 13.
Data R2 and R3 are read from. Similarly, data is sequentially written into one frame memory and data is read from the other two frame memories.

Next, the aliasing determiner 15 will be explained. Here the fifth
As shown in the figure, with respect to the blood flow direction in the blood vessel, a flow approaching the ultrasound probe 1 is defined as a forward direction, and a flow moving away from the ultrasound probe 1 is defined as a reverse direction.

As shown in Figure 6, the median value 32 of the 6-bit flow velocity data (0 to 63) is set to 0, 0 to 32 is the flow velocity in the opposite direction (fruits and vegetables), and 32 to 63 is the flow velocity in the forward direction (red). system).

FIG. 7 is a diagram for explaining folding due to blood flow. If aliasing has not occurred, the interpolated data of data F, F2 contained in 0 to 63 is the data FI
It becomes 2. However, if a turn occurs, the interpolation data will be at the FH position because it moves to F2 where F2 becomes (F2+64), for example. However, this value is 64
Because of the above, the value of the lower 6 bits is turned around, that is, the value FL of (FH-64).

In this way, the aliasing determiner 15 compares the data F, , F2 input from the MUX 14, and compares the data F, , F2.
If the absolute value of the difference is larger than a certain threshold level and the signs are different, it is determined that the aliasing is due to blood flow, and information for commanding aliasing is sent to the interpolator 15.
Output to.

Here, the threshold level is 3 of the total value.
Approximately /8 is appropriate, and in the case of 64 data, 24 is good. The aliasing determiner 15 is, for example, an adder, E x
It may also be a comprehensive OR gate or a comparator.

The interpolator 16 performs various interpolations on the blood flow information of the current frame and the previous frame outputted from the MUX 14, depending on the determination result of the aliasing determiner 15.

Interpolator 16 can be implemented with an adder or a multiplier.

First, a case will be described in which the judgment result of the aliasing determiner 15 is that aliasing has not occurred.

For example, the data R1 and R read out by the interpolator 16
2, the correction frame (R1+
R2)/2. In this case, 1□ is generated for a blood vessel located in the center based on 1 for a blood vessel relatively to the right on the frame and 2 for a blood vessel relatively left. Similarly, interpolation frames are generated by sequentially interpolating between adjacent frames.

The interpolated frame data obtained in this way and the MUX
The current frame data and the previous frame data outputted from the MUX 14 are outputted to the color processing circuit 6B in chronological order as shown in FIG. 3 by the MUX 17. In this way, since interpolated frames can be inserted, the number of frames is twice as large as the conventional number of frames. In other words, since the image that used to be about 5 frames per second is displayed at 10 frames, which is twice as many, the image becomes smoother and easier to see.

Next, the interpolator 16 calculates the lower 6 of (F+ + (F2 +64)l /2) as shown in FIG.
Outputs bit data FL. In this way, when generating interpolated frame data, interpolation is performed taking aliasing into consideration, so that appropriate interpolated frame data can be generated.

Next, a second embodiment of the present invention will be described. FIG. 8 is a schematic configuration diagram showing an interpolator 16a provided in the DSC as a main part of the second embodiment.

This interpolator 16a consists of a 16 x 8 bit read-only memory (ROM), and performs the aliasing judgment, frame interpolation, MUX14.
17 are controlled. That is, ROM16a
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. 9, in the case of F≧F2, ■When the switching signal is 00, the lower 6 bits of data FL of iF++ (F2 +64)l/4
Output.

■When the switching signal is 01, (F, 10 (F2+64)
The lower 6 bits of data FL of l/2 are output.

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

(2) When the switching signal is 11, the lower 6 bits of F2 are output.

(2) Next, as shown in Figure 10, if F<F2, ■When the switching signal is 00, +3(FI+64)+F2
)/4 lower 6 bits of data FL are output.

■When the switching signal is 01, ((F1 + 64) + F 2
)/2 lower 6 bits of data FL are output.

■When the switching signal is 10, ((F1+64)+3F2
Outputs data FL of the lower 6 bits of 1/4.

(2) When the switching signal is 11, the lower 6 bits of F2 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.

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.

Note that the present invention is not limited to the embodiments described above. In the embodiments described above, color Doppler images have been described for BDF images that display tomographic images (B-mode images) and color Doppler images, but the present invention can also be applied to tomographic images.

In this case, there is no need to take aliasing into account, so it can be realized using only an interpolation circuit. Also, FF7 is added to the BDF image.
The present invention can be applied to BDF image/FF image to which images are added. In short, it goes without saying that various modifications can be made without departing from the gist of the present invention.

[Effects of the Invention] According to the present invention, diagnostic information consisting of tomographic image information and two-dimensional blood flow information is written alternately into a plurality of frame memories,
Since the diagnostic information of the current frame and the diagnostic information of the previous frame are interpolated, diagnostic information of an intermediate frame between these frames can be generated. This allows the number of frames to be increased several times over the conventional number of frames, making the ultrasound image smoother and easier to view.

In addition, since it determines whether the blood flow is aliased, if there is aliasing, interpolation is performed that takes aliasing into consideration when generating an interpolated frame, so an ultrasound diagnostic device that can generate an appropriate interpolated frame can be used. Can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of an ultrasonic diagnostic device according to the present invention, FIG. 2 is a diagram showing details of a DSC provided in the device, and FIGS. 3 and 4 are diagrams showing the inside of the DSC. Figure 5 is a diagram showing the forward flow and reverse flow of blood in a blood vessel, Figure 6 is a diagram showing the allocation of flow velocity data for forward flow and reverse flow, and Figure 7 is a diagram to explain the action of the interpolator. FIGS. 8 to 10 are diagrams for explaining folding due to flow, and are diagrams for explaining a second embodiment of the present invention. 1... Ultrasonic probe, 2A... Pulse generator, 2B
... Transmission delay circuit, 2C ... Pulser, 3A ... Preamplifier, 3B ... Reception delay circuit, 3c ... Adder, 4A ... Logarithmic amplifier, 4B ... Envelope detection circuit,
4C...A/D, 5A...phase detection circuit, 5B...
・A/D, 5C...MTI filter, 5D...autocorrelator, 5E...calculation unit, 6A...DSC, 6B・
...Color processing circuit, 6C...D/A, 6D...Color monitor, 11-13...Frame memory, 141
7...MUX. 15... aliasing determiner, 16... interpolator.

Claims (2)

[Claims] (1) Obtain tomographic image information based on the received signal obtained by transmitting and receiving ultrasound to and from the subject, detect the Doppler shift signal due to blood flow, and detect the Doppler signal with a filter to create a two-dimensional image. In an ultrasonic diagnostic apparatus that obtains blood flow information and displays this diagnostic information via a storage means, the storage means includes a plurality of frame memories into which the diagnostic information that is sequentially input in frame units is written, and a plurality of frame memories in which the diagnostic information is sequentially input in units of frames. An ultrasonic diagnostic apparatus comprising: means for reading diagnostic information of the current frame and the previous frame; and interpolation means for interpolating the diagnostic information of the current frame and the previous frame read by the means. (2) Detect the Doppler shift signal due to blood flow based on the received signal obtained by transmitting and receiving ultrasound to and from the subject, detect the Doppler signal with a filter, and obtain two-dimensional blood flow information. In an ultrasonic diagnostic apparatus that displays blood flow information via a storage means, the storage means includes a plurality of frame memories into which the blood flow information is sequentially input in frame units, and a current frame and a previous frame from these frame memories. a means for reading out blood flow information of the current frame and a previous frame read by the means, a determining means for determining whether or not the blood flow turns back by comparing the blood flow information of the current frame and the previous frame read by the means; An ultrasonic diagnostic apparatus comprising: interpolation means for performing various types of interpolation on the read blood flow information of the current frame and the previous frame.