JPS6234539A - Ultrasonic doppler blood stream meter - 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] [Summary] In an ultrasonic Doppler blood flow meter that simultaneously displays B-mode images and blood flow velocity, n pieces of ultrasonic data are collected for each B-mode scan and Doppler analysis is performed. I will do it.

The first ultrasound data of each scan is passed through a high-pass filter, which causes a large error, so it is discarded and only the remaining ultrasound data is used.

[Industrial application field]

The present invention relates to an ultrasonic Doppler blood flow meter used in an ultrasonic diagnostic device, and in particular, an ultrasonic Doppler blood flow meter useful in an ultrasonic diagnostic device that displays blood flow information superimposed on a B-mode image. Regarding the meter.

[Conventional technology]

As shown in FIG. 3, the ultrasonic diagnostic apparatus uses an ultrasonic transducer 31 to scan a living body 30 in a fan shape with ultrasonic waves, and displays blood flow on a B-mode image that displays the reflected image. There is a system in which Doppler images showing the condition are displayed in a color format overlapping each other.

This type of device has the advantage of enabling more accurate diagnosis in that the movement of organs such as the heart and the associated dynamic changes in internal blood flow distribution can be observed simultaneously.

In such a device, ultrasonic waves are transmitted and received 0 times (for example, 8 times) in the scanning direction 1 of the B mote image, and
It is necessary to repeat the operation of transmitting and receiving ultrasonic waves 0 times in l for all scanning directions, and for each scanning direction,
A received waveform as shown in FIG. 4 for n=8 is obtained.

In FIG. 4, ■, ■, . . . , ■ indicate the times of transmission and reception, al , a2 + . ..., b8 indicates the signal portion of the reflected ultrasound.

By the way, in living organisms, there are generally various discontinuous layers such as the outer walls of organs that have high reflectance, so transmitted ultrasound is multiple-reflected between these walls, and some of the reflected waves received are , their multiple reflected waves are usually superimposed. The multiple reflected waves include not only those based on the transmitted ultrasonic waves of that time, but also those based on the transmitted ultrasound waves of each previous time.

However, between different scanning directions, shadows are less likely to occur because of scratches in the direction of the ultrasonic transducer 31 and the direction of the reflected waves.

Therefore, in each scanning direction, the number of multiple reflected waves in the received reflected waves for the first time is smaller than for the other times.

In addition, in normal biological measurements such as those of the heart, the movement of the wall that causes multiple reflections is often relatively slow compared to the speed of blood flow. For this reason.

Because the Doppler shift frequency will be a low frequency.

Generally, it is removed using a high pass filter HPF.

Figure 5 shows an example of a received wave data sequence obtained when ultrasonic transmission and reception was performed eight times in one of two scanning directions, before passing through the high-pass filter HPF (a), and (1)
The waveforms of ff1 and bl are shown in contrast.

[Problem that the invention seeks to solve]

In a conventional ultrasound diagnostic apparatus, Doppler blood flow information ta is collected during scanning to obtain a B-mode image.

Since the received waves obtained by the first ultrasonic transmission and reception in each scanning direction do not include multiple reflected waves from the wall, the second ultrasonic transmission and reception, as illustrated in Fig. 5(a), A large discontinuity occurs between the received wave and the received wave. When such a signal train was passed through a high-pass filter to remove the β-type reflected wave component from the wall, there was a problem in that the above-mentioned discontinuous parts turned into noise over a wide frequency range and had an adverse effect. .

[Means for solving problems]

In the present invention, in each scanning direction of a B-mode image.

When the number of data required for Doppler analysis to determine blood flow velocity is n, ultrasonic transmission and reception is performed n + 1 times to collect n+1 received wave data, among which the first received wave data is Discard it and pass only the second and subsequent n pieces of received wave data through a high-pass filter.

It was designed to be used for Doppler analysis.

FIG. 1(A) is a conceptual diagram of an ultrasonic diagnostic apparatus showing the basic structure of the present invention in an exemplary manner.

In the figure, 10 is a living body, 11 is an ultrasound transducer, 12 is an ultrasound signal generation circuit, 13 is a quadrature detector, 1
4 is an A/D converter, 15 is a high-pass filter HPF, 1
Reference numeral 6 represents a buffer memory, 17 a frequency analysis section, 18 a display section, 19 a B mode control section, and 20 a timing control circuit.

The illustrated configuration is basically the same in configuration and function as the conventional device, except that the timing control circuit 20 has been improved for selective control of received wave data.

The ultrasonic transducer 11 is controlled so that its directivity changes in a fan shape within a certain range with respect to the living body lO in the B-mode operating state. There are 9 methods of mechanical rotation and a method of controlling the phase of the element array.

The ultrasonic signal generation circuit 12 generates an ultrasonic burst signal at regular intervals to drive the ultrasonic transducer 11. The ultrasonic transducer 11 is.

An ultrasonic burst wave is emitted into the living body 10 and one reflected wave is received. Transmission and reception are performed n+1 times (n is a positive integer determined by the specifications of the frequency analysis unit 17) in the same scanning direction.

The received reflected wave is orthogonally detected by a quadrature detector 13,
Separated into two signals, Sin and Cos, and further A/D
After being converted into a digital signal by the converter 14, it is passed through a digital filter type high-pass filter (PF15).
It is stored in the buffer memory 16.

At this time, the timing control circuit 20 ignores the first one of the n+1 received wave data input for each scanning direction and prevents it from being sent to the high-pass filter HPF"15.

That is, in the illustrated example, the A/D converter 14.

By a control signal from timing control circuit 20.

The operation is enabled only for n times of received wave data from the second time onwards, excluding the first time, in each scanning direction.

Note that similar signal selection can be performed by providing an appropriate signal gate without using the A/D converter 14.

Next, the n times of Sin stored in the buffer memory 16 are
For the received wave data of and Cos, extract the values at the same timing position from each time.

The signal is supplied to the frequency analysis section 17.

The frequency analysis section 17 obtains the Doppler shift frequency, converts it into a blood flow velocity value, and outputs it to the two display sections 18 .

On the other hand, the B-mode control unit 19 performs output display control of the B-mode image based on the received wave signal output from the ultrasound transducer 11. Thereby, for example, the blood flow velocity can be displayed on the display unit 18 in color on the B-mode image.

Note that the control for removing the first received wave data from the n+1 pieces of received wave data is performed by the ultrasonic transducer 11.
It can be performed at any position between 15 and 15.

[Effect]

According to the present invention, two pieces of ultrasonic wave data are originally transmitted and received one more than the n pieces of received wave data required for Doppler analysis, so some time is wasted and the operating frequency is reduced accordingly.

However, since the first piece of discontinuous received wave data that occurs each time the scanning direction is switched is not input to the high-pass filter, noise is reduced and the accuracy of single frequency analysis is improved.

FIG. 1B shows an example of a received wave data string (al) that is manually input to the high-pass filter and a received wave data string (bl) that is output from the high-pass filter.

The illustrated example is for n=8.

[Embodiment] FIG. 2(A) shows the configuration of main parts centering on a timing control circuit according to an embodiment of the present invention. Also the second
Figure (B) is an operation timing diagram.

In FIG. 2(A), 20 is a living body, 21 is an ultrasonic transducer, 22 is a scanning control circuit, 23 is an ultrasonic signal generation circuit, and 24 is a signal gate circuit.

25 is a timing control circuit, 250 is a transmission timing signal generation circuit, 251 and 252 are counters, 253 is an OR circuit, 254 is a transmission timing signal, 255 is a reception enable signal, and 256 is a scanning direction switching signal.

The ultrasonic signal generation circuit 23 generates a transmission timing signal 254
An ultrasonic burst signal is generated at a constant period based on the ultrasonic transducer 21
to drive.

The ultrasonic transducer 21 placed on the living body 20 is
Ultrasonic waves are transmitted into the living body 20 and reflected waves thereof are received. At this time, the scan control circuit 22 controls the scanning direction of the ultrasound transmission and reception, that is, the direction of the directivity.

The scanning control circuit 22 receives an 8-bit scanning direction switching signal 2 output from the counter 256 of the timing control circuit 25.
56, the scanning direction is sequentially switched. In the illustrated example, the scanning direction is switched by controlling the signal phase of the element array that constitutes the ultrasonic transducer 21.

Ultrasonic transmission and reception are performed nine times for each scanning direction.

The reflected wave signal received each time by the ultrasonic transducer 21 is applied to the signal gate circuit 24 via the scanning side '<I11 circuit 22.

The signal gate circuit 24 is an OR gate circuit of the timing control circuit 25.
The received reflected wave signal is transferred to the subsequent stage only when the reception enable signal 255 output from the circuit 253 is ON.

The timing of the reception enable signal 255 is set so as to invalidate only the first reception reflected wave signal.

The timing control circuit 25 transmits a transmission timing signal 254
．． Reception enable signal 255 and scanning direction switching signal 2
56 is generated.

The transmission timing signal 254 is generated by the transmission timing signal generation circuit 250 and applied to the ultrasonic signal generation circuit 23 and the counter 25.

The counter 251 is a 9-ary frequency dividing counter composed of 4 bits, and as shown in FIG. 2(B), as the transmission timing signal 254 is input, (
A counting operation is performed in which the count progresses by two in a circular manner from (0000) to (100Q).

The OR circuit 253 takes the logical sum of the 4-bit output from the counter 251, and as shown in FIG. 2(B), when the value is (0000), it is 5, that is, 2 for each scanning direction.
Only during the period when the first ultrasonic wave transmission/reception is performed, the output reception enable signal 255 is set to "O" to shut off the signal gate circuit 24 and discard the first reception reflected wave signal.

During the remaining period, the output of the OR circuit 253 is always “1”.
'', therefore, the signal gate circuit 24 passes the received reflected wave signals from 2 times to 8 times as valid signals.

The counter 252 is an 8-bit binary counter, and is driven by the carry signal of the counter 251.
In order to switch the scanning direction every 51 cycles, the 8-bit scanning direction switching signal 256 is updated.

The scanning control circuit 22 switches the scanning direction to the direction specified by the scanning direction switching signal 256 before the next transmission timing signal is generated.

〔Effect of the invention〕

According to the present invention, it is possible to prevent discontinuities between received reflected waves occurring in each direction of B-mode scanning from affecting frequency analysis results via a high-pass filter, and to reduce noise in Doppler. A blood flow meter can be provided.

[Brief explanation of the drawing]

FIG. 1(A) is a diagram showing the basic configuration of the present invention. FIG. 1 (B) is an explanatory diagram showing the action of the present invention, and FIG. 2 (A
) is a configuration diagram of the main parts of one embodiment of the present invention, FIG. 2 (B) is its timing chart, FIG. 3 is an explanatory diagram of B-mode scanning, and FIG. 4 is a received reflected wave obtained in each scanning direction. A waveform diagram of a signal train, FIG. 5 is an explanatory diagram showing an example of processing of a received wave data train in a conventional high-pass filter. Figure 1 (, to) middle. 10: Living body 11: Ultrasonic transducer 12: Ultrasonic signal generation circuit 13: Quadrature detector 14: A/D converter 15: High pass filter HP F 16: High sofa memory 17: Frequency analysis unit 18: Display Section 19: B mode control section 20: Timing control wholesale circuit

Claims (1)

[Claims] In an ultrasonic diagnostic apparatus that displays Doppler blood flow information along with an ultrasonic B-mode image, ultrasonic waves are transmitted in one ultrasonic transmission/reception direction of B-mode scanning, where n is an arbitrary positive integer. Ultrasonic Doppler characterized in that, when the number of times is n+1, Doppler analysis is performed using the received wave data of the second and subsequent n times, excluding the received wave data from the first ultrasound transmission. Blood flow meter.