JPS58200732A - Ultrasonic dobra device - 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 flow velocity in a living body. The object of the present invention is to provide an ultrasonic Doppler device that can obtain blood flow velocity information.

First, a conventional Doppler apparatus using ultrasonic pulses will be explained. FIG. 1 is a tomographic diagram illustrating the relationship between a blood vessel in a living body and an ultrasonic pulse beam.

In the figure, an ultrasonic pulse beam 2 emitted from an ultrasonic probe 1 passes through a blood vessel indicated by a blood vessel wall 3. A part of this transmitted ultrasound pulse is scattered by the blood in the blood vessel. This scattered ultrasound pulse is received by the ultrasound probe 1. From the received signal, the Doppler pulse at the time corresponding to position 4 is Extract the signal. Figure 2 is a block diagram of a conventional ultrasound Doppler device. The reference oscillator 5 has a frequency of 3 MHz.
generates a 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 ultrasonic probe 1 receives ultrasonic echo signals returned from the living body.

After the received echo signal is amplified by the amplifier 7, the reference signal generated by the reference excavator 5 is shifted in phase by 00 and 90 degrees, and is used as a comparison signal to be sent to the quadrature detector 8 to generate quadrature detection signals va and vb. Output. Furthermore, the detected signals υa and vb are extracted by the gate circuit 9 for a period corresponding to the Doppler extraction position 4 shown in FIG. Outputs Va and vb. This signal is further converted into a digital signal by an A/D converter 11,
The frequency analyzer 12 performs analysis processing, and blood flow velocity information is output and recorded by the recorder 13.

As explained above, blood flow velocity information at the Doppler signal extraction position 4 can be obtained.However, as shown in the blood vessel wall 3' shown in FIG. The position of moves with time. The Doppler signal extraction position in the blood vessel that has moved in this way should move to a new Doppler signal extraction position 4' as the blood vessel moves. This movement of the Doppler signal extraction position is performed by detecting the position of the blood vessel wall from the echo signal. However, with the conventional apparatus, sufficient accuracy cannot be obtained in detecting the position of the blood vessel wall for Doppler signal extraction. Also, in the device, a quadrature detector 8
There are constraints due to the phase relationship between the comparison signal and the gate position.
Cannot be set freely. Therefore, when the extraction position moves, there is a drawback that the quality of blood flow velocity information is significantly degraded due to the error in the extraction position. The purpose of the present invention is to provide an ultrasonic Doppler device that can obtain high-quality blood flow velocity information by moving the Doppler signal extraction position using the following steps.Examples of the present invention will be described below with reference to the drawings. .

FIG. 3 is a tomographic diagram illustrating the relationship between a blood vessel in a living body and an ultrasonic pulse beam. The ultrasonic pulse beam 2 emitted from the ultrasonic probe 1 passes through the blood vessel indicated by the blood vessel wall 3 . A portion of this transmitted ultrasound pulse is scattered by the blood in the blood vessel.

The scattered ultrasound pulses are received by the ultrasound probe 1. Doppler signals at each time corresponding to positions 4-1 to 4-2 degrees are extracted from this received signal. FIG. 4 is a block diagram showing an embodiment of the ultrasonic Doppler apparatus according to the present invention.

The reference oscillator 5 generates a 3■H reference signal. Based on this signal, the transmitter 6 supplies transmission pulses to the ultrasound probe 1 at a frequency of 4 KHz, and emits the ultrasound pulses into the living body.

The ultrasound probe 1 receives ultrasound echo signals returned from the living body. After this received echo signal is amplified by the amplifier 7, the reference signal generated by the reference generator 6 is oO and 900.
The quadrature detector 8 outputs quadrature detection signals va and vb using the phase-shifted signal as a comparison signal. Furthermore, the detected signals va and vb are extracted from the Doppler signal extraction position 4 in FIG.
Gate circuits 9-1 to 9-20 corresponding to -1 to 4-20
Accordingly, only the corresponding period is extracted. The extracted signals are time-integrated by integrators 10-1 to 1o-20, each signal corresponding to one transmission, to output Doppler signals V, a, and vb.

This signal is further converted into a digital signal by A/D converters 11-1 to 11-20, and frequency analyzers 12-1 to 12-20 convert this signal to a digital signal.
12-20 performs analysis processing and outputs blood flow velocity information. One piece of blood flow velocity information is selected by the tracking (!l circuit 4) from the 20 pieces of output blood velocity information, the blood flow velocity is corrected, and the recorder 13 records it.

FIG. 5 shows a more detailed configuration of the tracking circuit 14.
This is a diagram. The position of the blood vessel wall is detected by the blood vessel wall detection circuit 14-1 from the echo signal which is the output of the amplifier 7 shown in FIG. Based on the detected blood vessel wall position data, blood flow velocity information is selected by the selection circuit 14-2 and switch 14-3.

Furthermore, the average moving speed of the blood vessel is detected by the speed detection circuit 14-4. The detected velocity component of the blood vessel in the ultrasound beam direction is corrected by the subtraction circuit 14-5 based on the selected blood flow velocity information, and is output to the recorder 13.

FIGS. 6a and 6b show changes in the intensity of the received echo signal in the blood vessel wall detection circuit 14-1. The signal shown in FIG. 3A is the intensity change of the echo signal near the blood vessel wall 3 in FIG. 3, and the time shown in A in FIG. 6 indicates the position of the blood vessel wall 3. If the position of the blood vessel wall at another time is shown in Fig. 3 (2), the intensity change of the echo signal also changes as shown in Fig. 6, and the time showing the blood vessel wall also moves to the mouth, and the movement of the blood vessel wall The amount can be detected. Note that the position of the blood vessel wall that can be detected from the signals shown in FIGS. 6a and 6b has sufficient accuracy to determine the moving speed of the blood vessel wall.

FIG. 7a is an example of a sonogram display of the blood flow velocity information selectively outputted by the switch 14-3 in FIG. 5, and FIG. is the velocity component in the ultrasound beam direction,
FIG. TC shows the blood flow velocity information outputted from the subtracting circuit 14-5 at this time in annogram display. In addition, the seventh
The moving speed V of the blood vessel shown in the figure is calculated by assuming that the apparent speed detected from the echo signal is V, and the angles between the direction of the ultrasonic pulse beam and the movement direction of the blood vessel wall and blood vessel are α and β, respectively. The moving speed is determined by equation (1). However, the blood vessel wall should be approximately straight.

As described above, according to the present invention, blood flow velocity information can be detected at a fixed position, so very high quality blood flow velocity information can be obtained at a fixed position in a moving blood vessel.

Note that the selection circuit 14-2 selects the A/D converters 11-1 to 1
1-20 to select the Doppler signals Va and Vb.

Next, other embodiments of the present invention will be described. FIG. 8 is a block diagram of the ultrasonic Doppler apparatus according to this embodiment.

Similarly to FIG. 3, the quadrature detection signals va and vb obtained from the quadrature detector 8 are extracted by the gate circuit 9 only during the period for extracting the Doppler signals at the positions 4-1 to 4-20 shown in FIG. This extracted gate signal is shown in FIG. 9a. This sampled signal is time-integrated by an integrator 10, and A/
t shown in FIG. 9 by the D converter 11. -t2°, the output of the integrator 11 is converted into a digital signal Va(t
) and Vb(tn). However, n is an integer from ○ to 20. Therefore, Va(tn) and V
b(t) is expressed by the following equations (2) and (3).

Further, it is assumed that t follows the following equation, where Tn is the Doppler signal extraction timing corresponding to the positions 4-1 to 4-20 shown in FIG.

1 +1 Tn-- and 1-2 ・・・・・・(4) (However, n=1
~20) Next, the Doppler signal Van to be extracted in the storage unit 15
, Vbn are obtained by subtracting the following equation and temporarily stored.

Van=Va(tn)Va(tnl)・”・”(5)V
bn=Vb (tn) vb (tnl) ””(
6) This storage unit 16 stores the latest Van and Vbn each time an ultrasound pulse is transmitted and received for a plurality of ultrasound pulses, and stores the latest Van and Vbn obtained from the past 128 transmissions and receptions.
is stored. Furthermore, the value of n corresponding to the appropriate position is determined using the signal of the blood vessel wall detection circuit 14-1 obtained in the same manner as explained in FIG. The signal is transferred to the frequency analyzer 12' for analysis processing. The obtained blood flow velocity information is corrected by the blood vessel velocity using the subtractor 14-5 in the same manner as described in FIG. 6, and is recorded by the recorder 13.

As described above, the output of the integrator is A/D converted, and the A/D
If the Doppler signal component is extracted by finding the difference between the converted values, the signal extraction circuit becomes simple. Furthermore, by temporarily storing the extracted signal in a memory, etc., and reading out only the necessary data for frequency analysis, the number of complex frequency analyzers can be reduced to one.
decreases to .

Note that the speed detection circuit 14-4 shown in FIGS. 5 and 8
The blood flow velocity information may be directly output without providing the subtraction circuit 14-5. In particular, it is not necessary when the moving speed of blood vessels is sufficiently slower than the speed of blood flow. Furthermore, the Doppler signal extraction position in Figure 3 and the Van and Vbn used for frequency analysis in Figure 8
The number is not limited to the above embodiments and can be set freely.

Furthermore, the blood vessel wall detection circuit 14-11 of FIG. 5 or FIG.
A delay section can also be provided after 9. This delay section allows the time delay of each section to be adjusted, and the 128 pieces of Van and Vbn data for frequency analysis are divided into timing data before and after the transmission/reception cycle of the ultrasonic pulse that detected the blood vessel wall. Frequency analysis can be performed using .

As described above, according to the present invention, Doppler signals at multiple positions are extracted, blood vessel positions are separately determined, and
The Doppler signal at the selected position is frequency-analyzed to obtain blood flow velocity information, so the movement of the blood vessel is tracked with high precision and the blood flow velocity information at a certain position in the blood vessel is calculated. can be obtained without compromising quality.

[Brief explanation of the drawing]

Fig. 1 is a tomographic diagram of a living body illustrating the conventional Doppler signal extraction position, Fig. 2 is a block diagram illustrating an example of a Doppler device using the conventional method, and Fig. 3 shows the Doppler signal extraction position in the present invention. FIG. 4 is a tomographic diagram of a living body to be described, and FIG. 6 is a block diagram of an ultrasonic Doppler apparatus in an embodiment of the present invention, FIG. 6a. b is a waveform diagram explaining the detection operation of blood vessel wall movement, Fig. 7a
"c is a diagram explaining processing of blood velocity information, FIG. 8 is a block diagram explaining another embodiment of the present invention, FIG. 9a,
b is a timing diagram illustrating the operation of the device of FIG. 8; 1... Probe, 3... Blood vessel wall, 4...
... Doppler signal extraction position, 5 ... Reference oscillator, 6 ... Transmitter, 8 ... Quadrature detector, 9.9-1 to 9-20- ...O gate circuit, 11
．． 11-1 to 11-20...A/D converter, 1
2, 12'... Frequency analyzer, 13...
... Recorder, 14... Tracking circuit, 14-1 ・
...Vessel wall detection circuit, 14-2...Selection circuit, 14-3...Switch, 14-4...
...Speed detection circuit, 14-6...Subtraction circuit. Name of agent: Patent attorney Toshio Nakao and one other person
1 Figure! Figure 2 Figure 3? Figure 4 Figure 5 Figure 16 Figure 17 Figure 8 Figure 9

Claims (3)

[Claims] (1) means for emitting ultrasound pulses into the subject to obtain echo signals; means for extracting Doppler signals at a plurality of positions within the subject from the echo signals; and means for frequency analyzing the Doppler signals. and a means for detecting the position of the subject; and one of the Doppler signals extracted by the extracting means, or a plurality of Doppler signals extracted by the extracting means analyzed by the frequency analyzing means. An ultrasonic Doppler apparatus characterized in that it is provided with means for selecting one of the objects according to the position of the subject detected by the detecting means. (2) the means for extracting integrates a signal obtained by phase-detecting the echo signal using the emission timing of the ultrasonic pulse as a period; and means for sampling the integrated value in the integration interval by the integrating means at a plurality of points; The ultrasonic Doppler apparatus according to claim 1, further comprising means for determining the difference in amplitude of the integral value between two points sampled by the sampling means. (3) The ultrasonic dowel according to claim 1 or 2, wherein the extracting means comprises means for storing Doppler signals corresponding to the emission of a plurality of ultrasonic nodules. Device.