JPS58200731A - Ultrasonic doppler apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic Doppler device used to obtain information on blood velocity in a living body. The object of the present invention is to provide a sonic Doppler device.

Conventionally, the ultrasonic Doppler method has been used as a means of simultaneously obtaining blood flow velocity information at many depths within the body, and a circuit has been used to extract Doppler signals from the ultrasonic echo signals for each depth to be measured. Ta. The principle of ultrasonic pulse Doppler method is described, for example, by Hiroshi Furuhata.

“Ultrasonic pulse Doppler blood flow meter”, Electronic Medicine, No. 23,
Published in December 1976, it is well known as explained in . However, regarding the conventional example described below, see Masaaki Chiyama et al., "Multi-channel Norse Doppler blood flow meter using a minicomputer", Confucian Technology MBE 79-63 +
Published in 1986, it is also explained.

The conventional method disclosed in the document ``Extracting an ultrasonic pulse beam and Doppler signals at nine points in a living body'' will be described below. FIG. 1 is a tomographic diagram of a living body illustrating the relationship between blood vessels in the living body, ultrasonic pulse beams, and extraction positions. Emit an ultrasonic pulse beam 3 from an ultrasonic probe 1,
The ultrasound probe 1 receives an echo signal. The positions 4-1 to 4-9 from which Doppler signals are extracted are inside the blood vessel of the living body and between the blood vessel walls 2. Therefore, positions 4-1~
By frequency-analyzing the Doppler signal at 4-9, the distribution state of blood flow velocity in the blood vessel can be obtained.

Next, a conventional ultrasonic Doppler device will be explained.

FIG. 2 is a block diagram of a conventional ultrasound Doppler device.

Reference oscillator 5 generates a 3 MHz reference signal. Based on this signal, the transmitter 6 supplies transmission pulses to the ultrasound probe 1 at a cycle of 4 KHz, and emits the ultrasound pulses into the living body. Further, the ultrasound probe 1 receives ultrasound echo signals returned from the living body. After this received echo signal is amplified by an amplifier 7, a quadrature detection signal va is generated by a quadrature detector 8.
and obtain vb. The quadrature detector 8 uses a signal obtained by shifting the 3 MHz reference signal of the reference oscillator 5 by 00 and 9o0 as a comparison signal, and outputs va and vb, which are the products of the comparison signal and the input echo signal. Additionally, the va
and vb are extracted at Doppler signal extraction positions 4-1-1 to 11- shown in FIG. 1 by nine gate circuits 9-1 to 9-9.
9, the signal corresponding to one transmission is time-integrated as a unit, and the Doppler signal (val, v51) at each extraction position is obtained.
(va9.V59) is obtained. The Kono signal is further temporarily stored by sample and hold circuits 12-1 to 12-9,
A/D converter 1 is sequentially selected by selection switch 13.
4 into a digital signal and supplies it to a frequency analyzer 15. The frequency analyzer 15 independently analyzes and processes the V and Vb signals corresponding to each extraction position, and
This information is output as individual blood flow velocity information and recorded by the recorder 16. Frequency analysis is performed on temporal changes in va and vb obtained in time series with a transmission period of 4 kHz. In addition,
The gate signal generator 10 controls each gate time of the gate circuits 9-1 to 9-9. FIG. The transmission pulses to be transmitted are shown. In the figure, b l CI and d I e are gate signals that control the gate circuits 9-1, 9-2, 9-3, and 9-9, respectively. There is a delay by the time required for the ultrasound to travel back and forth between the Doppler signal extraction positions 4-1.4-2.4-3 and 4-9 and the probe 1. Also, the pulse width of the gate signal is Determine the depth resolution at a location.

The means for extracting the Doppler signal described above can obtain blood velocity information for many depths at the same time.
11-9 and sample bold circuits 12-1 to 12-9
is required, and the same number of gate signals must also be generated.

Therefore, if the number of depths to be taken out is large, there is a drawback that the apparatus becomes very large-scale.

The present invention aims to eliminate such drawbacks and provide an ultrasonic Doppler device that can obtain blood flow velocity information at many depths with a simple device. explain.

The extraction positions of the Doppler signal in the living body are nine points shown as positions 4-1 to 4-9 in FIG. 1, as in the conventional example.

An ultrasonic Doppler apparatus according to an embodiment of the present invention will be explained with reference to the block diagram of FIG. Reference oscillator 5 is 3MHz
generates a reference signal. This signal causes the transmitter 6
supplies transmission pulses to the ultrasonic probe 1 at a cycle of 4 KHz, and emits the ultrasonic pulses into the living body. Furthermore, the ultrasound probe 1 receives ultrasound echo signals returned from the living body. After amplifying this received echo signal with amplifier 7,
Quadrature detection signals V 1 and vb are obtained by the quadrature detector 8 .

The comparison signal of the quadrature detector 8 is a signal shifted by 0° and 900 phase from the 3 MHz reference signal which is the output signal of the reference oscillator 6, and outputs the products V and V of this comparison signal and the input signal. This output signal is time-integrated by an integrator 11 to obtain Va(t) and Vb(t). Here, t is a delay time from the integration start time of the integrator 11. The signal Va(t) is supplied to the A/D converter 14 via the switch 13', and the -power signal vb(t) is supplied to the A/D converter 14 via the delay line 17 and the switch 13', and is converted into a digital signal. A
/D converter 14 performs 20 A/D conversions, and va(
tn) and vb(tn).

However, n is ○ to 9. The frequency analyzer 15' obtains nine Doppler signals (■a1.vb1) to (■a9.V59) from the obtained va(tn) and vb(tn), and frequency-analyzes them as independent signals. Each Doppler signal is a signal obtained in time series with a transmission period of 4 KHz. The analysis results are output from the frequency analyzer 15' as blood velocity information at each extraction position shown in FIG. 1, and are recorded by the recorder 16.

Next, the timing of A/D conversion will be explained.

5A to 5E are diagrams for explaining the timing of A/D conversion, and FIG. 5A shows the timing of emitting ultrasonic pulses. The timing for performing A/D conversion is the time shown in the figure, which is delayed from t0 to t9 from the integration start time, and 10 A/D conversions are performed.
Perform D conversion. Furthermore, the Doppler signal extraction positions 4-1 to 4-9 shown in FIG. do. Therefore, ΔT=T −T (1) n+1
n It becomes a submerged relationship. Furthermore, for to-t9, ΔT=
t (...(3)n n-1. Also, the digital signal Va(tn) is Va(tn
)=5" Z/a(t)dt-...This is an example. The time width corresponding to the pulse width of the conventional gate signal that determines the resolution in the depth direction of each extraction point is ΔT. Next , supplying the digital signal va(tn) to the frequency analyzer 16';
Van is determined according to equation (6).

van-va(tn)-va(tn-1)...
(5) However, n=1 to 9 On the other hand, vb(t) is delayed by dt via the delay line 17, and is supplied to the A/D converter 14 via the switch 13', as shown in FIG. It is converted into a digital signal at the timing shown in C in the same figure, which is delayed by Δ from the timing. t ten Δt
The digitized code converted in time is vb(t), as shown by the following equation.

Here, dt is set to 1/2 of ΔT, and the conversion process by the A/D converter 14 is performed 20 times per one transmission cycle from time .to to time t9+Δt at intervals of ΔL.

In addition, the switch 13' is activated by the signal shown in FIG. 5d.
The inputs of the A/D converter 14 are Va(t) and v5(t)
The signal is switched alternately. V obtained in this way
b(tn) is processed by frequency analyzer 15' in the same way as va(tn).
and calculate v5n according to equation (7).

"bn= Vb(t'n)-Vb(tn,)-song-(7
) However, n-1 to n-9 Note that e in the figure is a timing signal that determines the integration interval of the integrator 11.

As described above, according to this embodiment, one integrator 11 and one delay line
7 and a simple switch 13', Doppler signals can be extracted and a large number of points can be observed simultaneously.

FIG. 6 is a block diagram of an ultrasound Doppler apparatus according to another embodiment of the present invention. Compared to the embodiment of FIG. 4, the delay line 17
The difference is that va(tn) and Vb(tn) are processed separately by excluding the switch 13' and the switch 13' and further dividing into VD converters 14-1 and 14-2. Still A/D
The timing of conversion is shown in FIGS. 7a-C. Figure γa shows the transmission timing, Figure γ shows the A/D conversion timing, Figure C shows the integration period, and A/D conversion timing
From 0 to t9, processing is performed in parallel in A/D converters 14-1 and 14-2. Further, A/D conversion is performed 10 times per transmission cycle from to to t9 at intervals of ΔT.

Therefore, there is no complicated timing such as switch switching or time delay, resulting in a simpler configuration.

In the above embodiments, the A/D conversion intervals were equal intervals of dt and ΔT, but the invention is not limited to this. T shown in Figure 8a
Suppose that n n+1 Doppler signals are extracted at the timings of
n In the device shown in the block diagram of Figure 6, to tnl, tnl
A/D conversion is performed at each timing of 1°t'n+1, and a Doppler signal is extracted according to the following equations (8) and (9).

van=Va(橢)-Va(tn) ------・(
8) Vbn-v5(t'n)-v5(tn)...
・(9) It is also possible to set an even wider integration interval and reverse the order of tlo and tn+1 as shown in C of the same figure, and v
an and V5n can be determined using equations (8) and (9).

Note that tn and t'n shall comply with the following equation.

As yet another example, the timing of A/D conversion is set to an integer fraction of the reference signal. Further, the width of the integration interval is set to be an integral multiple of the period in which this A/D conversion is performed. At the timings shown in FIG. 9 a - d, a is the reference signal, FIG. 9 is the A/D conversion timing at the same timing, and C is the Doppler extraction position TN, tn
It can be set freely as long as it is the timing of t or the center position of the timing interval of t. If the integration interval width is n times the period of A/D conversion and tn+□ from t shown in d of the figure, then vaN, vbN, and TN are determined by the following equations.

VaN-Va(tn+m)-va(tn)...
(11) VbN-vb(tn+m)-vb(tn)...
(12) Therefore, if the A/D conversion is set at a fast cycle and at an integer multiple of the phase detection signal, the Doppler signal can be generated at any position and by the width of the integration interval by simply selecting and subtracting the digital signal. can be extracted. Furthermore, this position and integral interval can be easily changed by changing the software that defines the calculation method.

As explained above, according to the present invention, the Doppler signal component is detected by phase-detecting the ultrasonic echo signal, performing interval integration on this signal, sampling this integral value, and finding the difference between the sampled data. Doppler signal components at many depths can be extracted simultaneously with a simple device.

[Brief explanation of the drawing]

Figure 1 is a tomographic diagram of a living body explaining the Doppler signal extraction position, Figure 2 is a block diagram showing a conventional ultrasonic Doppler device, and Figures 3 a - e explain the gate timing of the device. 4 is a block diagram showing an embodiment of the ultrasonic Doppler apparatus of the present invention, FIG. A block diagram showing another embodiment of the ultrasonic Doppler device of the invention, FIGS. 7a-c are diagrams showing the timing of A/D conversion in the same embodiment, FIGS. 8a-C and FIGS. 9a-c. d is a diagram explaining the timing of A/D conversion in different examples. 1... Probe, 2... Blood vessel wall, 4-1
~4-2... Doppler signal extraction position, 5...
...Reference oscillator, 6...Transmitter, 8...
・Quadrature detector, 11...fist...integrator, 14.14-
1.14-2...A/D converter, 15 and 15
'... Frequency analyzer, 16... Recorder. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 1 Figure 3 (α1 (dl) ゛(e) 1M Figure 4 Figure 5 Town 16 Figure 17 Illustration

Claims (2)

[Claims] (1) means for emitting ultrasonic pulses into the subject to detect the phase of the Kobushita echo signal; and means for integrating the detected signal obtained by the detecting means with the emission timing of the ultrasonic pulses as a period; , comprising means for extracting integral values at a plurality of points within the same interval where the integration is performed, and means for frequency analyzing a difference signal between the integral values at the two points obtained by the extracting means. Ultrasonic Doppler device. (2) The ultrasonic Doppler apparatus according to claim 1, wherein the means for extracting the integral value at a plurality of points performs the extraction using a signal synchronized with a comparison signal of the means for detecting the phase.