JPH0292347A - Color ultrasonic diagnostic apparatus - Google Patents

Abstract

PURPOSE:To easily judge blood flow and to enhance the detection efficiency of blood flow by providing an operational processing means for adding a dispersion value to the mean flow velocity outputted from a color flow mapping part to set the max. flow velocity and performing color gradation display due to said max. flow velocity. CONSTITUTION:An ultrasonic pulse is transmitted to an object to be detected from an ultrasonic probe 1 and an echo signal containing a Doppler shift signal is received by the same probe 1 to be applied to a regeneration and operation part 9. Multiplication due to mixers 17a, 17b is performed in a color echo data line 9B and this result is applied to the low-pass filters(LPF) 18a, 18c of the CFM operation part 14 to detect only the Doppler shift signal fd as a phase detection output signal. The mean velocity V is operated from the result of frequency analysis by a mean velocity operation part 22 and a dispersion value sigma<2> is operated by a dispersion operation part 23 and power P is further operated by a power operation part 24. Then, color gradation display is performed on the basis of the display of the obtained max. flow velocity Vmax. As a result, since the presence of blood flow is easily judged, the detection efficiency of blood flow can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a color ultrasound diagnostic apparatus that displays blood flow information of a subject in color using the Doppler effect of ultrasound.

(Prior art) When an ultrasonic pulse is transmitted from a probe to a blood flow flowing inside a living body, the center frequency fc of this transmitted pulse is Doppler-biased by the moving blood cells in the bloodstream. The frequency changes by fd due to the shift, fd+fc=f
are received by the same probe as ultrasonic pulses. At this time, the Doppler shift frequency @, fd is expressed by the following equation in which the blood flow velocity ■ is reflected.

2VCOSθ fd=　　　　　　・fc to Here, v: m flow velocity, θ: angle between the ultrasonic pulse and blood flow, C: speed of sound.

Therefore, by detecting the Doppler shift frequency fd, the blood flow velocity (2) can be detected.

In order to display the blood flow velocity (2) obtained in this way as a two-dimensional image, the following method is used. First of all, the 6th
As shown in the figure, A, B, C,
When performing a sector scan by sequentially transmitting ultrasonic pulses in the directions, the ultrasonic diagnostic apparatus having the configuration shown in FIG. 7 performs scan control of the ultrasonic pulses.

When an ultrasound pulse is first transmitted in the direction, the echo signal that is Doppler-shifted and reflected by the blood flow inside the subject is received by the same probe 1, converted into an electrical signal, and then sent to the receiving circuit. Sent to 2. Next, a Doppler shift signal is detected by the phase detection circuit 3, and this Doppler shift signal is captured at each of, for example, 256 sample points (SP) provided in the direction of the ultrasound pulse. The Doppler shift signal captured at each sample point is subjected to frequency analysis by a frequency analyzer 4, and the analysis results are A/D converted and sent to a DSC (digital scan converter). blood flow images are displayed in real time as two-dimensional images. The same operation is repeated for each of the directions B, C, . . . , and a blood flow image corresponding to each skittle direction is displayed.

In addition, based on such Doppler signals, a CFM (color flow mapping) unit calculates the average flow velocity Q of blood velocity ■, power P1 dispersion σ2, etc., and displays these two-dimensionally in color in real time. A color ultrasonic diagnostic apparatus is known. In such a device, the average flow velocity is particularly important as diagnostic information, and the Doppler signal is processed using the AC (autocorrelation) method and the FFT (fast Fourier transform).
Frequency analysis is performed using methods such as the method and the spectrum is displayed. FIG. 8 shows the power spectrum displayed in this way, and the detected Doppler signal has a range of 10 to 10
Contains clutter signal @SB with 0x power. This clutter signal Ss moves slowly compared to the movement of blood flow I! ii, and consists of low frequency components.

(Problem to be Solved by the Invention) However, in conventional color ultrasound diagnostic equipment, when diagnosing the circulatory system, low frequency components generated from slow-moving parts such as the heart wall are converted into Doppler signals. This causes a problem in that it becomes difficult to determine the presence or absence of blood flow, and the blood flow detection efficiency decreases. For example, in FIG. 8, the average flow velocity Q is affected by the clutter signal SB and is shifted toward lower frequencies, making it difficult to detect the blood flow signal.

The present invention has been made in response to the above-mentioned problems.
It is an object of the present invention to provide a color ultrasonic diagnostic device that facilitates blood flow detection.

[Configuration of the Invention (Means for Solving the Problems) To achieve the above object, the present invention adds a variance value σ2 to the average flow velocity output from the color flow mapping section to obtain the maximum flow velocity v max. , arithmetic processing means for performing color gradation display based on this v max is provided.

(Function) The average flow velocity σ and the variance value σ2 output from the color flow mapping section are each panned into, for example, an RGB conversion table and both are added to display v max,
Performs color gradation display. J: to the beans R (red), B
(Blue) gradation display and G(
Green) gradation display. In this case, the algorithm for subtracting v max is changed depending on the value of beans and σ2. This makes it easy to distinguish blood flow, thereby increasing blood flow detection efficiency.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the color ultrasonic diagnostic apparatus of the present invention, in which an ultrasonic probe 1 applies ultrasonic waves to a subject based on a repetitive signal fr applied from an oscillator 7 via a transmitting/receiving circuit 8. A sound wave pulse is transmitted, and an echo signal containing a Doppler signal is received by the same probe 1 and applied to the transmitter/receiver circuit 8. In the transmitter/receiver circuit 8, the delay data of each transducer at the time of transmission is corrected so as to have an inverse relationship to that at the time of reception, and after phased addition is performed, the echo signal is inputted to the reproduction calculation section 9.

The reproduction calculation section 9 has a B/W (black and white) echo data line 9A.
and a color echo data line 9B. The echo signal applied to the B/W echo data line 9A is envelope-detected by the amplitude detector 10, and then subjected to black-and-white DSC.
After the echo is applied to the attenuator 11 and the reflected intensity of the echo is recorded, it is sent to the attenuator 12.

On the other hand, the echo signal applied to the color echo data line 9B is phase-detected by the phase detector 13, this detection output is applied to the CFM calculation section 14, this ringing output is applied to the color 030 section 15, and further this DSC output is RGB
It is output to the converter 16.

FIG. 2 shows details of the color echo data line 9B including each component as described above.

The echo signals are applied in two channels to mixers 17a and 17b, respectively, to detect forward and reverse blood flow. The reference signal fr from the oscillator 7 and a signal whose phase is shifted by 90 degrees by the phase shifter 25 are also added to each of the mixers 17a and 17b to perform multiplication. The Doppler shift signal fd and (2fo+fd> signal) are detected from the echo signal, and the detected outputs are outputted from the L of the CFM calculation unit 14, respectively.
It is added to PF (low pass filter) 18a and 18b. As a result, the signals are input to each LPF 18a, 18b, and the high frequency components (2fo and fd) are removed to obtain only the Doppler shift signal fd, which becomes the phase detection output signal for the blood flow image.

The phase detection output signal is output from the A/D converter 19a.

19b and converted into a digital signal, the MT
I (moving target indicator) 20a,
20b. As a result, unnecessary reflected signals (clutter signals) from slow-moving parts such as the wall of the heart, other than the blood flow information included in the detection output signal, are removed. The output signals of the MTI filters 20a, 20b are applied to an autocorrelator 21. This autocorrelator 21 is for performing frequency analysis, and is used because it is necessary to perform two-dimensional multi-point frequency analysis. These frequency analysis results are output to the average speed calculation section 222, variance calculation section 23, and power calculation section 24, respectively. The average speed calculation unit 22 calculates the average speed, the variance calculation unit 23 calculates the variance value σ2, and the power calculation unit 24 calculates the power P.

The pots output from these CFM calculation units 14.

σ2. Each data of P is added to the color 030 section 15 and recorded, thereby forming color image data.

The output of the color 030 unit 15 is applied to an RGB conversion unit 16 to generate R, G, and B signals. Figure 3 shows this RG
This figure shows details of the B converter 16, in which a v max converter 16A is connected upstream of a conventionally used RGB converter 16B having an RGB conversion table. The V maX conversion section 16A has a function of calculating V maX based on an algorithm as shown in the table below, and performs trunk tightening based on the average flow velocity and variance value σ2 added from the collar 030 section 15, and calculates 1q. The RGB converter 16B converts the v max
Output to. In addition, the v max converter 16A has RGB
A conversion mode selection signal is applied. Depending on the bean, gradations of R (red) and B (blue) are displayed, and σ2
G (green) gradation display is performed by.

Margin table below: v max calculation algorithm Note that σ indicates the standard deviation value, which is determined by the square root of the variance value σ2.

If we set the range of ■ to -0,5≦V≦0.5 and the range of σ2 to O≦σ2≦1, then
true is indicated by cytrue=AK-Ji6'T.

Here, beans correspond to fd/dr.

Also, A: coefficient (O≦A≦1) or becomes.

Incidentally, the coefficient aA can be performed in the same manner as the input of the RGB conversion mode selection signal of the Vmax9 converter 16A, and this A
By varying Vmax, it is possible to avoid changing the effectiveness of Vmax, and the closer it gets to 1, the greater the variable amount of Vmax can be. Also, when set to O, the average speed display is the same as the conventional average speed display.

Regarding how to determine Mame-σ and Mame-0σ, I have a question.

σ2. An example of converting each data of P into RGB signals is shown in the fourth example.
Shown in Figures (a) and (b). As is done in the general display method of conventional CFM devices, zo data and R, 8-gradation data are shown in FIG. 4(a).

The thick line in (b) shows cases where there is correspondence.

Although the horizontal axis shows the beans corresponding to the input signal, it can be realized by making the RGB conversion section 16 function so as to correspond to v max instead of this summer. This is the ROM (read only memory) of the RGB converter 16.
It can be easily adapted by simply changing the contents of the code, and basically the hardware does not change.

Here, an example of a method for calculating σ2 will be shown using a formula.

After quadrature detection (after passing through IPF > 1/f of 208.20b
N complex time series signals x (t) with r period x(t)=
ΣAi-el) (jωi- is 10 jφi) (,", t=1.2. ..., N> Ai: is the angular frequency ωi acid component amplitude φi: is the angular frequency ωi acid component phase, then the autocorrelation Summer and σ2P in the FFT method and the FFT method are as follows.

(1) In the case of autocorrelation method (O≦σ2≦1) Here, the output Re of the autocorrelator 21, 1m, is Re=ΣA
i2 −CO3(ωi) jm−ΣAi2−3IN (ωi), and the pseudo O-order, first-order, and second-order moments QO,Q due to autocorrelation
l, Q2 are QO=ΣA12 (2) In the case of the FFT method, after Fourier transformation, the angular frequency ωi acid component power spectrum Pi becomes Pi=Ai2.

Here, the 0th, 1st, and 2nd moments PO, P1゜P2
The R, G, and B signals output from the RGB conversion section 16 are the R, G, and B signals output from the attenuator 12.

Combined with the B signal by the combiner 26! After being made into an I'4 RGB signal, it is converted into an analog signal by a D/A converter 27 and displayed on a color monitor 28.

Next, the operation of this embodiment will be explained.

Ultrasonic pulses are transmitted from the ultrasound probe 1 to the subject, and a signal containing a Doppler shift signal (O≦σ2≦1) is transmitted from the ultrasound probe 1 to the subject.
) After the core signal is received by the same probe 1, the reproduction section 9
added to. The echo signal is partially branched into a B/W echo data line 9A and a color echo data line 9B,
Amplitude detection is performed on the B/W echo data line 9A, and phase detection is performed on the color echo data line 9B to detect a Doppler shift signal. That is, in the color echo data line 9B, after multiplication is performed by the mixers 17a and 17b, this result is sent to the LPF 1 of the CFM operating section 14.
8a and 18b, the Doppler shift signal f
Only d is detected as a phase detection output signal. After this detection output is converted into a digital signal, the MHI filter 2
0a and 20b remove unnecessary reflected signals, and an autocorrelator 21 performs frequency analysis. The results of this frequency analysis are used to calculate the average speed V by the average speed calculating section 22, and the variance value σ is calculated by the variance calculating section 23.
2 is performed, and the power P is further calculated by the power calculation section 24.

These worries, σ2. After each data of P is converted by the color DSC unit 15 so that it can be displayed on a standard color monitor, ■ and σ2 are respectively added to the RGB conversion unit 16. In this RGB conversion unit 16, v max conversion unit 16
By adding wa and σ2 to A, max is fflg based on the algorithm shown in the table above, and this v max is added to the RGB converter 16B, so that R, G, B is converted by this conversion table. A signal is created.

In such a case, the v max conversion unit 1 of the RGB conversion unit 16
R (red) and B (blue) gradations are displayed by the beans added to 6A, and G (green) gradations are displayed by σ2.

FIG. 5 shows a power spectrum illustrating the concept of displaying v max that is 1q in this way, where v max is expressed as 9+σ (square root of variance value σ2).

According to this embodiment, color gradation display is performed based on the max display that is 1q as described above, so that it is not possible to reduce the influence of low frequency components caused by clutter signals as in the conventional method. become able to. Therefore, the presence or absence of blood flow can be easily determined, so that the detection efficiency of blood flow can be improved.

In this embodiment, an example is shown in which frequency analysis is performed using an autocorrelation method, but it is also effective to perform frequency analysis using a fast Fourier transform method, and the same effect can be obtained by 1q. Moreover, this makes it possible to realize the device with a simple configuration.

[Effects of the Invention] As described above, according to the present invention, since the variance value σ2 is added to the average flow velocity V to display v max and color gradation display is performed, it is easy to determine the presence or absence of blood flow. The detection efficiency can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the color ultrasound diagnostic apparatus of the present invention, FIG. 2 is a block diagram showing the configuration of the main parts of FIG. 1, and FIG. 3 is a block diagram showing the structure of the main parts of FIG. 2. 4(a) and (b) are characteristic diagrams explaining the operation of this embodiment, FIG. 5 is a power spectrum explaining the operation of this embodiment, and FIGS. 6 and 7 are conventional diagrams. FIG. 8 is a sector scanning pattern diagram and a block diagram showing an example, and a power spectrum explaining the conventional problems. 1... Ultrasonic probe, 9... Reproduction calculation section, 9A.
... B/W (black and white) echo data line, 9B... Color echo data line, 13... Phase detector, 14... CFM (color flow mapping) calculation section, 16. RGB conversion section, 16A・VmaX conversion section, 21・
...Autocorrelator, 22... Average speed calculation section, 23...
・Distributed calculation unit. Reed area, TAzur worker's tongue fig. fig. fig.

Claims (1)

[Claims] In a color ultrasound diagnostic device that sends and receives ultrasound pulses to a subject and displays blood flow information in color based on the Doppler signal obtained using the Doppler effect, the average output from the color flow mapping unit Dispersion value σ for flow velocity @V@
^2 to obtain a maximum flow velocity Vmax, and a color gradation display based on this Vmax is provided.