JPH02121641A - Ultrasonic blood flow imaging apparatus - Google Patents

Abstract

PURPOSE:To easily synthesize a blood flow image and a B-mode image by converting an echo signal digitally using the first pulse signal as a clock while converting a Doppler signal to a digital signal using the second pulse signal as a clock to calculate blood flow data. CONSTITUTION:The first pulse signal is used as a sampling clock to digitally convert an echo signal by a conversion means 6 and the second pulse signal is used as a sampling clock to digitally convert a Doppler signal by a conversion means 8. Next, the blood flow signal calculated on the basis of the Doppler signal is stored in a blood flow data memory means 11 and the second pulse signal is used as a reading signal to read the blood flow signal by a conversion means 12 and the read blood flow signal is converted analogously. Further, the first pulse signal is used as a sampling clock to digitally convert the analogously converted blood flow signal by a conversion means 14 and, at last, this digitally converted blood flow signal is converted to a display signal along with the echo signal by a digital scanning converter 15 to be displayed on a color monitor 17.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an ultrasonic blood flow imaging apparatus, and more particularly to an ultrasonic blood flow imaging apparatus that synthesizes and displays B-mode imaging and blood flow imaging.

[Prior Art] An ultrasonic blood flow imaging apparatus displays blood flow imaging along with B-mode imaging. B-mode imaging is a two-dimensional image that modulates the intensity of the echo signal reflected from the subject.
Displays in black and white depending on the signal strength. Furthermore, blood flow imaging displays the speed and direction of blood flow using color components.

Blood flow imaging involves transmitting ultrasound waves into the subject, receiving the ultrasound waves reflected from the subject, and measuring the difference between the frequency of the transmitted ultrasound waves and the frequency of the received ultrasound waves. It is obtained by calculating the Doppler shift frequency corresponding to the blood flow velocity.

In general, blood flow imaging displayed in color is often inferior in spatial distance resolution compared to B-mode imaging displayed in black and white because it places too much emphasis on frequency resolution and S/N ratio.

Therefore, in B-mode imaging, the period of the sampling clock (hereinafter referred to as sampling clock PE) when converting the echo signal, which is an analog signal, to digital in the distance direction is longer than the period of the sampling clock (hereinafter referred to as sampling clock PE) when converting the echo signal, which is an analog signal, to digital in the distance direction. The period of the sampling clock PD (hereinafter referred to as sampling clock PD) is longer.

In this case, a transmission trigger is output (see Figure 3 (a))
The period of the sampling clock PD (see Fig. 3 (C)) in the digital conversion performed every time is synchronized with the sampling clock PH, and is the frequency of the sampling clock PE divided by 1/N (N is a positive integer). There is (3rd
(See Figure (b)), the process of combining B-mode imaging and blood flow imaging in DSC can be performed relatively easily.

[Problems to be Solved by the Invention] However, when attempting to configure an ultrasonic blood flow imaging device by adding a function to display blood flow imaging to a device that performs B-mode imaging, sampling for digitally converting Doppler signals is required. If the period of the clock PD and the period of the sampling clock PE for digitally converting the echo signal are different or not in a multiple relationship, it becomes difficult to combine blood flow imaging and B-mode imaging. There was a problem.

The present invention has been made to solve the above problems,
Even if the sampling clock PD for digital conversion performed for blood flow imaging and the sampling clock PD for digital conversion performed for B-mode imaging are different or do not have a relationship of multiples, the blood flow cannot be processed by DSC. An object of the present invention is to provide an ultrasonic blood flow imaging device that can easily combine flow imaging and B-mode imaging.

[Means for Solving the Problems] An ultrasonic blood flow imaging apparatus according to the present invention includes a first pulse signal generating means for outputting a first pulse signal of a predetermined period, and a first pulse signal as a sampling clock. , a first analog-to-digital conversion means for digitally converting the echo signal, and a second pulse signal having a period different from that of the first pulse signal.
a second pulse signal generating means for outputting a pulse signal;
a second analog-to-digital converter that digitally converts the Doppler signal using the second pulse signal as a sampling clock; and a blood flow data that calculates blood flow data based on the digitally converted Doppler signal, and a blood flow signal that corresponds to the blood flow data. blood flow data calculation means for outputting blood flow data, and blood flow data in a first-in, first-out system in which the blood flow data is temporarily written and the blood flow data is read out using a pulse signal outputted by the second pulse signal generation means as a readout signal. a storage means, a digital-to-analog conversion means for converting blood flow data into analog;
a third analog-to-digital conversion means for digitally converting analog-converted blood flow data using the first pulse signal as a sampling clock; and an echo signal digitally converted by the first analog-to-digital conversion means and a third analog-to-digital conversion Data conversion means converts the blood flow signal digitally converted by the means into data for display.

[Function] In the ultrasonic blood flow imaging apparatus having the above configuration, the first analog-to-digital conversion means digitally converts the echo signal using the first pulse signal outputted by the first pulse signal generation means as a sampling clock, The second analog-to-digital conversion means outputs the second pulse signal from the second pulse signal generation means.
The Doppler signal is converted into a digital signal using the pulse signal as a sampling clock.

Next, the blood flow signal calculated based on the Doppler signal is stored in the blood flow signal storage means, and the digital-to-analog conversion means reads out the blood flow signal and converts it into analog using the second pulse signal as a readout signal.

Furthermore, the third analog-to-digital conversion means digitally converts the analog-converted blood flow signal using the first pulse signal as a sampling clock, and finally, the digital scan converter converts the digitally converted echo signal and the third
The analog-to-digital conversion means converts the digitally converted blood flow signal into a signal for display.

[Example 1] Hereinafter, an example of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram of an ultrasonic blood flow imaging apparatus according to an embodiment of the present invention. In FIG. 1, 1 is a probe that transmits an ultrasonic signal into a subject 2 and receives an echo signal reflected from the subject 2, and 3 is a probe 1.
4 is a beamformer, 5 is a B-mode analog processing circuit that performs processing such as logarithmically amplifying the echo signal, and 6 is an analog-to-digital converter (hereinafter referred to as A) that converts the echo signal, which is an analog signal, into a digital signal. /D), 7 is a Doppler analog processing circuit that divides the echo signal into two channels, multiplies them by a reference wave with a phase difference of 90'', and performs processing such as Doppler demodulation to detect the Doppler signal, and 8 is a Doppler signal that is an analog signal. A to digitally convert
D and 9 are MTI filters; IO is a blood flow data calculation circuit that calculates blood flow data such as blood flow velocity from the Doppler signal and outputs a blood flow signal corresponding to the calculated blood flow data; 11 is a blood flow data calculation circuit that outputs a blood flow signal corresponding to the calculated blood flow data; 12 is a digital-to-analog converter (hereinafter referred to as D/A) that converts the blood flow signal, which is a digital signal, into analog; 13 is a smoothing filter;
14 is an A/D that digitally converts the blood flow signal converted into an analog signal by D/A 12, and 15 is an angle θ.
and a distance r from the probe 1. A DSC (digital scan converter) converts the position within the subject 2 of the echo signal and blood flow signal expressed by the polar coordinate values of and the distance r from the probe 1 into the position expressed by the orthogonal coordinate value xy, 16 is an echo D/A converts signals and blood flow signals into analog; 17 is a color monitor;
18 is a pulse signal generation circuit that outputs a pulse signal P1 with a predetermined period T1, and 19 is a pulse signal generation circuit that outputs a pulse signal P2 with a predetermined period T.

This ultrasonic blood flow imaging device has a pulse signal generation circuit 1
The operation timing is determined by the pulse signals P1 and P2 outputted by the terminals 8 and 19.

The A/Ds 6 and 14 use the pulse signal P1 outputted by the pulse signal generation circuit 18 as a sampling clock to digitally convert the echo signal and the blood flow signal, respectively. Also, A
/D8 digitally converts the Doppler signal using the pulse signal P2 outputted by the pulse signal generation circuit 19 as a sampling clock. Further, the blood flow data memory 11 is a first-in first-out (FIFO) memory, and the pulse signal P
2 is used as a read signal.

Note that the smoothing filter 13 may have a simple configuration since the A/D 14 performs oversampling.

Next, the operation of the ultrasonic blood flow imaging apparatus shown in FIG. 1 will be explained with reference to the timing chart shown in FIG. 2.

First, an ultrasonic signal is transmitted from the probe 1 at a predetermined timing. The timing for transmitting ultrasonic signals is shown in Figure 2 (
This is achieved using the wave transmission trigger shown in a). The probe 1 transmits waves five times as shown in Fig. 2(e) for each sound ray shown in Fig. 2(b). The probe 1 transmits the echo signals reflected by the subject 2. When it receives the wave, it outputs it to the transmitting/receiving circuit 3.

The beamformer 4 performs beamforming on the echo signal and distributes and outputs it to the Doppler analog processing circuit 7 and the B-mode analog processing circuit 5. Figure 2 (
As shown in d), the echo signals for the first four scans are sent to the Doppler analog processing circuit 7, and the echo signals for the last scan are sent to the B-mode analog processing circuit 5.
be distributed to.

The Doppler analog processing circuit 7 performs Doppler demodulation on the echo signal to obtain a Doppler signal, A/D 8 +:l:
Output. As shown in FIG. 2(e), the A/D 8 samples the Doppler signal using the pulse signal P2, converts it into a digital signal, and outputs it to the MTI filter 9. The MTI filter 9 removes strong echo components without Doppler shift from the digitally converted Doppler signal, and the blood flow data calculation circuit 10
Output to.

The blood flow data calculation circuit 10 calculates the blood flow velocity from the Doppler signal, and stores the blood flow signal corresponding to the calculated blood flow velocity in the blood flow data memory 11.

The Doppler memory 11 operates using the pulse signal P2 as a write signal, as shown in FIG. 2(r), and stores blood flow data. The blood flow signals stored in the Doppler memory 11 are shown in Fig. 2 (g
), the pulse signal P2 is read out as a readout signal, converted into analog by the D/A I2, further converted into digital by the A/D 14 via the smoothing filter I3, and output to the DSC15.

On the other hand, the B-mode analog processing circuit 5 to which the echo signal for the last wave transmission is input performs logarithmic amplification or the like on the echo signal and outputs it to the A/D 6.

As shown in FIG. 2(h), the A/D 6 samples the echo signal using the pulse signal P1 output from the pulse signal generation circuit 16, converts it into digital data, and outputs it to the DSC 15.

The DSC15 is obtained by sector scanning and converts the positions of echo signals and blood flow signals indicated by polar coordinate values into orthogonal coordinate values, that is, the positions in the main scanning direction and sub-scanning direction of the color monitor 17, and stores them in the frame memory ( (not shown)
write to. In this case, since the blood flow signal digital conversion and the echo signal digital conversion use the same pulse signal P1 as a sampling clock, blood flow imaging and B-mode imaging can be easily synthesized.

The D/A 16 operates in synchronization with the operation of the DSC 15, converts the converted data into analog, and outputs the converted data to the color monitor 17. The color monitor 17 synthesizes and displays B-mode imaging corresponding to the echo signal and blood flow imaging corresponding to the blood flow signal.

[Effects of the Invention] As explained above, according to the present invention, an echo signal is digitally converted using a first pulse signal as a sampling clock, and a second pulse signal having a period different from that of the first pulse signal is converted into a digital signal. as the sampling clock,
After converting the Doppler signal into a digital signal to calculate blood flow data, the blood flow signal is converted into an analog signal as a readout signal using a blood flow data storage means, and then the second pulse signal is converted into an analog signal. By converting to digital using the sampling clock, even if the period of the sampling clock of digital conversion for B-mode imaging is different from the period of the sampling clock of digital conversion for blood flow imaging, it is possible to perform B-mode imaging and This has the effect of providing an ultrasonic blood flow imaging device that can be easily combined with blood flow imaging.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an ultrasonic blood flow imaging device according to an embodiment of the present invention, Fig. 2 is a timing chart showing the operation of the ultrasonic blood flow imaging device shown in Fig. 1, and Fig. 3 is a conventional It is a timing chart showing the operation of the ultrasonic blood flow imaging device. DESCRIPTION OF SYMBOLS 1... Probe, 2... Subject, 3... Transmission/reception circuit, 4... Beam former, 5... B-mode analog processing circuit, 6.8.14... Analog-to-digital converter, 7... Doppler analog processing circuit, 10... Blood flow data calculation circuit, 11... Doppler memory, 12.16
...Digital analog converter, 13...Smoothing filter, 15...DSC. ...color monitor, 18. 19...Pulse generation circuit.

Claims (1)

[Claims] B-mode imaging based on echo signals that are transmitted from within the subject by transmitting ultrasonic waves and reflected from the subject, and based on Doppler signals obtained by coherently detecting the echo signals. In an ultrasonic blood flow imaging apparatus that synthesizes and displays blood flow imaging, the apparatus includes: a first pulse signal generating means that outputs a first pulse signal of a predetermined period; and an echo signal using the first pulse signal as a sampling clock. a first analog-to-digital conversion means for digitally converting the data; a second pulse signal generation means for outputting a second pulse signal having a period different from that of the first pulse signal; and a second pulse signal using the second pulse signal as a sampling clock. a second analog-to-digital conversion means for digitally converting the Doppler signal; a blood flow data calculation means for calculating blood flow data based on the digitally converted Doppler signal and outputting a blood flow signal corresponding to the blood flow data; A first-in, first-out blood flow data storage means in which blood flow data is temporarily written and the blood flow data is read out using a pulse signal outputted by the second pulse signal generation means as a readout signal, and blood flow data is converted into analog. a third analog-to-digital conversion means for digitally converting analog-converted blood flow data using the first pulse signal as a sampling clock; and an echo signal digitally converted by the first analog-to-digital conversion means. and data conversion means for converting the blood flow signal digitally converted by the third analog-to-digital conversion means into data for display.