JPH0425015B2 - - Google Patents

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to an ultrasonic diagnostic apparatus capable of obtaining tomographic image information and blood flow information, and in particular, to an ultrasonic diagnostic apparatus capable of obtaining tomographic image information and blood flow information. The present invention relates to an ultrasonic diagnostic apparatus that improves the rate and the number of rasters or frames.

[Technical background of the invention and its problems] In recent years, in ultrasonic diagnosis, the clinical value of a method that detects two-dimensional blood flow signals and real-time tomographic images using the same probe and displays them simultaneously using the ultrasonic pulsed Doppler method has been recognized. It's been getting worse. (Seo et al. Medical Lecture Collection, May 1983, 42-C-62) In the above method, the Doppler method is used to obtain blood flow information, so in order to obtain blood flow information for one raster, It is necessary to transmit and receive ultrasonic waves n times in the same direction. Here, the number of times of transmission and reception n is determined by the frequency resolution required for Doppler, and is usually performed 8 to 16 times in the case of two-dimensional Doppler. Further, the frequency resolution is determined by (ultrasonic transmission repetition frequency)/n.

In the above method, since the blood flow information echo and the tomographic echo are performed using the same probe and the same raster,
For example, if the repetition frequency of a tomographic image is 4kHz and 30 frames are displayed, the number of rasters obtained is fr
= repetition frequency/number of frames. here,
The number of rasters when displaying blood flow information at the same time is
fr/n. Furthermore, when obtaining blood flow information, the reflected echo from the blood flow is very small, 40 to 60 dB smaller than a normal tomographic image echo.

Therefore, in order to obtain blood flow information with a high S/N ratio, a low ultrasonic frequency of 2 to 3 MHz is usually used. Therefore, since blood flow information and tomographic image information are detected using low-frequency ultrasonic waves, the resolution of the tomographic image deteriorates.

Therefore, as a method to solve the above problem, the number of rasters can be reduced by providing receiving systems in parallel, setting the beam width of the transmitting raster wide, and making the beams of the receiving system different within that beam width, and receiving them simultaneously. A method of increasing the number of cells (Japanese Patent Application No. 52-105678) has been proposed. However, with this method, it is necessary to widen the transmission beam width, which reduces the directivity of the transmission, making it impossible to maintain a large raster interval for simultaneous reception, and if n times as many rasters are required, the receiving circuit is increased by n times, the circuit configuration becomes complicated, and it is impractical.

Furthermore, as another method for improving the number of rasters, a two-beam simultaneous display method (Iwata et al., Nichicho Medical Journal, May 1983, 42-C-50) has been proposed. In this system, when two cross sections are displayed overlappingly on the same display, a mechanical arm is used to detect the position between the probes to determine the positional relationship between the two cross sections using different probes. Therefore, the accuracy of position detection is low, and since the propagation paths of the ultrasound beams are different, there is a limit to the accuracy of positioning the two cross sections due to the difference in refraction of the living body and the speed of sound. Furthermore, the operability is also very poor since both hands must be used.

[Object of the invention] The present invention has been made based on the above circumstances, and
The purpose is to provide a practical ultrasonic diagnostic device that can improve resolution and the number of rasters or frames without degrading the image quality of tomographic images displayed together with blood flow information. It is in.

[Summary of the Invention] In order to achieve the above object, the present invention provides an ultrasonic transducer for transmitting and receiving ultrasonic waves; an ultrasonic transducer for transmitting and receiving ultrasonic waves; a transmitting/receiving means for simultaneously transmitting excited ultrasonic waves having a plurality of different frequency bands and receiving an echo signal from a reflector; and extracting a signal having a frequency band on a high frequency band side from the echo signal obtained by the transmitting/receiving means. means for obtaining the tomographic image information using the signal; and means for extracting a signal having a frequency band on the low frequency band side from the echo signal obtained by the transmitting/receiving means and using the signal for obtaining the blood flow information. It is characterized by comprising the following.

[Embodiment of the Invention] An ultrasonic diagnostic apparatus according to the present invention will be described below according to an embodiment shown in FIG.

In this embodiment, a sector scan type ultrasonic diagnostic apparatus will be described as an example.

In FIG. 1, 1A is a first deflection data generator that sets the amount of deflection of transmitted ultrasonic waves for detecting tomographic image information. 1B is a second deflection data generator that sets the deflection amount of the transmitted ultrasonic waves for detecting blood flow information.

2A and 2B are first and second deflection data generators 1
These are first and second transmission delay data generators that generate transmission delay data based on the deflection data output from A and 1B, respectively.

3A and 3B are first and second transmission delay circuit groups that generate delay pulse signals necessary for transmission deflection based on transmission delay data output from the first and second transmission delay data generators 2A and 2B, respectively. It consists of transmission delay circuits with the number of channels (CH) corresponding to the number of simultaneously driven oscillators.

4 includes a transducer group 5 formed by arranging a plurality of micro ultrasonic transducers, a first transmission delay circuit group 3A, a second transmission delay circuit group 3A,
3B is an excitation circuit that excites based on the delayed pulse signal output from the first and second amplifier groups 6.
It consists of A, 6B, an adder group 7, and a buffer 8.

A preamplifier group 9 amplifies the reflected wave signal from the transducer group 5 to a predetermined level.

10A and 10B are first and second reception delay data generators that generate reception delay data based on the deflection data output from the first and second deflection data generators 1A and 1B, respectively.

11 is a first and second reception delay data generator 10;
A first, which obtains a pulse signal necessary for reception deflection based on the reception delay data outputted from each of A and 10B, and performs reception delay processing on the reception signal from the preamplifier 9;
a second reception delay circuit group 12A, 12B;
This is a receiving circuit consisting of second filters 13A and 13B. Here, the first filter 13A extracts the center frequency _fH , and the second filter 13B extracts the center frequency _fL , and _fH > _fL .

14 is a detector that detects the received signal (for tomographic image information generation) having the center frequency f _H output from the first filter 13A.

Reference numeral 15 denotes a phase detector that detects the phase of the received signal (for blood flow information generation) having the center frequency f _L output from the second filter 13B.

16 is for two-dimensional Doppler detection to obtain two-dimensional blood flow information by analyzing the output from the phase detector 15, that is, the phase-detected signal of the received signal with the center frequency f _L for blood flow information generation, by frequency analysis, etc. It is a vessel.

17 is a DSC (Digital Scan) that takes in tomographic image information from the detector 14 and two-dimensional blood flow information from the two-dimensional Doppler detector 16, converts them into digital signals, and converts them from an ultrasound scan to a TV scan.
Converter).

A display 18 displays tomographic image information of the TV scan generated by the DSC 17 and two-dimensional blood flow information on the same screen.

Next, the operation of this embodiment configured as described above will be explained with reference to FIG. 1 and FIGS. 2 to 5.

Figure 2 is a diagram showing deflection in ultrasonic transmission and reception;
FIG. 3 shows the time waveform of the transmitter shown in FIG. Fourth
The figure shows the frequency spectrum of FIG. FIG. 5 shows the frequency spectrum of the received signal. In FIGS. 4 and 5, P represents power and f represents frequency.

In the actual device, focusing and deflection of the ultrasonic beam are performed by giving a time difference to each group of simultaneously excited transducers (N pieces), but since the specific operation is well known, we will not discuss it here. will only explain 1CH of the oscillator.

That is, in FIG. 1, the first deflection data generator 1A outputs the first deflection beam to the BI ₁ in FIG.
Set it so that Further, the second deflection data generator 1B generates the second deflection beam as B in FIG.
Set to ₁ . Next, the first deflection data generator 1
Using the data generated from A, the first transmission delay data generator 2A supplies delay time data necessary for changing the transmission beam to _B1 to each circuit of the first transmission delay circuit group 3A.

Here, the first transmission delay circuit group 3A is composed of the number of CHs corresponding to the simultaneously driven oscillators for transmission, and is necessary for deflecting each CH obtained from the first transmission delay data generator 2A. The pulse signal shown in FIG. 3a is generated.

The signal generated at this time is a pulse signal from which a signal with a bandwidth of the center frequency f _H can be efficiently obtained in the subsequent circuit as shown in FIG. 4a.

Next, the signal output from the first transmission delay circuit group 3A is amplified by the first amplifier group 6A to the amplitude necessary to excite the vibrator.
The signal shown in FIG. 3b is generated through a filter included in A.

On the other hand, the second deflection data generator 1B sets the deflection beam to be _B1 in FIG.
Next, using the data from 1B, the second transmission delay data generator 2B applies delay time data necessary for deflecting the transmission beam B ₁ to each circuit of the second transmission delay circuit group 3B.

Here, the second transmission delay circuit group 3B is composed of the number of channels corresponding to the simultaneously driven oscillators for transmission, and each of them is controlled by the data applied to the second transmission delay data generator 2B. A delayed pulse signal shown in FIG. 3c necessary for deflecting CH is generated. The signal generated at this time is transmitted to the fourth circuit in the subsequent circuit.
As shown in FIG. b, this is a pulse signal that can efficiently obtain a signal with a bandwidth of the center frequency f _L . Here, f _H >
f _L.

Next, the signal output by the second transmission delay circuit group 3B is amplified by the second amplifier group 6B of the excitation circuit 4 to the amplitude necessary to excite the vibrator, and is included in the second amplifier group 6B. The signal shown in FIG. 3d is generated through a filter.

Here, the signals output from the first and second amplifier groups 6A and 6B are added together by the adder group 7 to output the signal shown in FIG. 3e. As shown in FIG. 4c, the frequency spectrum of this signal includes signals in two different bands.

Next, the signal output from the adder group 7 is impedance-converted by a buffer 8 and excites the vibrator group 5. As a result, ultrasonic waves are transmitted from 11 in the direction of B1 in FIG. ₂ with a center frequency _fH , and ultrasonic waves are transmitted in the direction of _B1 with a center frequency _fL .

Next, the received signals obtained by these are received by the transducer group 5 and amplified by the preamplifier group 9.
A signal having the spectrum shown in FIG. a is applied to the first reception delay circuit group 12A and the second reception delay circuit group 12B. First and second reception delay circuit groups 12A, 12
B is equipped with the same number of CHs as the number of simultaneous reception transducers, and the operating method is to use the output data of the first deflection data generator 1A and the first reception delay data generation circuit 10A as shown in B1 of _FIG . Delay data that is in phase with each other is added to the first reception delay circuit group 12A. The signal obtained here is passed through the first filter 1.
3A, a band signal of center frequency f _H shown in FIG. 5b is extracted. As a result, the first filter 13
As the output of A, only the ultrasonic signal in the direction of _B1 in FIG. 2 is obtained.

Also, at the same time as above, the second deflection data generator 1B
Based on the output data, the second reception delay data generator 10B generates delay data whose phase matches the direction of _B1 in FIG. 2 to the second reception delay circuit group 12B.
Add to. The signal obtained here is passed through a second filter 13B to extract a band signal having a center frequency f _L shown in FIG. 5c. As a result, the second filter 13
As the output of B, only the ultrasonic signal in the direction of _B1 in FIG. 2 is obtained.

Next, the output of the first filter 13A is detected by the detector 14 and added to the DSC 17. DS
C17 converts the output signal of the detector 14 into a digital signal. On the other hand, the output signal of the second filter 13B undergoes phase detection by a phase detector 15, and the resulting signal is applied to a two-dimensional Doppler detector 16. Here, the DSC 17 converts the signal into a TV scan and first displays the output signal of the detector 14 on the display 18 as a tomographic image raster in the direction of _B1 in FIG.

Next, at the next transmission timing, the data of the first deflection data generator 1A is set to _B2 in FIG. It is set to _B1 in Figure 2.

When the number of repetitions in this manner reaches the number n at which the necessary frequency resolution of blood flow information is obtained, a blood flow information signal for one raster is output as the output of the two-dimensional Doppler detector 16, and the DSC 17 The blood flow information signal is displayed on the display 18 at the position in the raster direction _B1 .

Next, the data of the first deflection data generator 1A is set to Bn+1 in FIG. 2, the data of the second deflection data generator 1B is set to Bn+1, and the above steps are repeated in sequence.

As described above, according to this embodiment, ultrasonic waves are composed of frequency bands with different center frequencies, that is, ultrasonic waves in a high frequency band are used for detecting tomographic images, and ultrasonic waves in a low frequency band are used for detecting blood flow information. Since different deflections of ultrasound beams are transmitted and received using sound waves, blood flow information can be displayed simultaneously in real time without deteriorating the image quality of tomographic images.

Incidentally, although the scanning method in the above embodiment has been described as sector scanning, it goes without saying that it can also be applied to linear scanning or other scanning methods.

Further, as blood flow information, it is also applicable to a simultaneous display method of a 1-point pulsed Doppler device and a tomographic image.

The present invention is not limited to the above embodiments, and can be implemented with various modifications without departing from the gist of the present invention.

[Effects of the Invention] As described above, according to the present invention, an ultrasonic transducer for transmitting and receiving ultrasonic waves, an ultrasonic transducer for transmitting and receiving ultrasonic waves, and the ultrasonic transducer a transmitting/receiving means for simultaneously transmitting excited ultrasonic waves having a plurality of different frequency bands and receiving an echo signal from a reflector; and extracting a signal having a frequency band on a high frequency band side from the echo signal obtained by the transmitting/receiving means. means for obtaining the tomographic image information using the signal; and means for extracting a signal having a frequency band on the low frequency band side from the echo signal obtained by the transmitting/receiving means and using the signal for obtaining the blood flow information. By being characterized by having a It is possible to provide an ultrasonic diagnostic apparatus that can realize improvements.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the ultrasonic diagnostic apparatus according to the present invention, Fig. 2 is a diagram for explaining a method of deflecting an ultrasonic beam, and Fig. 3 is a transmission system in the configuration of Fig. 1. Signal wave diagram in each part of
FIG. 4 is a spectrum diagram of FIG. 3, and FIG. 5 is a spectrum diagram of the receiving system. 1A, 1B...first and second deflection data generators, 2A, 2B...first and second transmission delay data generators, 3A, 3B...first and second transmission delay circuit groups, 4 ...Excitation circuit, 5...Resonator group, 6A,
6B...first and second amplifier groups, 7...adder group, 8...buffer, 9...preamplifier group, 10
A, 10B...first and second reception delay data generators, 11...reception circuit, 12A, 12B...first and second reception delay circuit groups, 13A, 13B...
First and second filters, 14...detector, 15...
...Phase detector, 16...Two-dimensional Doppler detector,
17...DSC, 18...display unit.

Claims (1)

[Claims] 1. An ultrasonic transducer for transmitting and receiving ultrasonic waves, and an ultrasonic transducer that excites the ultrasonic transducer to simultaneously transmit ultrasonic waves having a plurality of different frequency bands and receive echo signals from a reflector. a transmitting/receiving means; a means for extracting a signal having a frequency band on the high frequency band side from the echo signal obtained by the transmitting/receiving means, and using the signal to obtain the tomographic image information; and a means for obtaining the tomographic image information from the echo signal obtained by the transmitting/receiving means. An ultrasonic diagnostic apparatus characterized by comprising means for extracting a signal having a frequency band on the low frequency band side from the signal and obtaining the blood flow information using the signal.