JPH05317312A - Ultrasonic diagnosing apparatus - Google Patents

Abstract

PURPOSE:To display an ultrasonic doppler image of high image quality with little noise by improving the transverse wave detecting efficiency of an ultrasonic doppler device. CONSTITUTION:An ultrasonic wave is transmitted into the inside of a tested body from an ultrasonic probe 1. The ultrasonic echo of the transmitted ultrasonic wave is received by the ultrasonic probe 1, and the ultrasonic echo information is sent to a transverse wave detecting part 17 through an amplifier 7-an adder 9. A reference correcting device 5 generates a reference signal different in frequency depending on the depth of a reflecting point of the ultrasonic echo. The transverse wave detecting part 17 performs transverse wave detection of the ultrasonic wave echo information according to the reference signal to be output as a doppler deviation signal. A frequency analyzing means obtains the blood flowing speed information in an examinee from the doppler deviation signal, and the blood flowing speed information is displayed on a display means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention transmits an ultrasonic wave into a subject and displays a tomographic image of the subject or blood flow velocity information in the subject based on echo information of the ultrasonic wave. The present invention relates to a sound wave diagnostic apparatus.

[0002]

2. Description of the Related Art FIG. 8 is a block diagram of a conventional ultrasonic diagnostic apparatus. The ultrasonic probe 1 is an array of N ultrasonic transducers. In order to transmit the ultrasonic waves into the subject, a reference signal having a frequency equal to the frequency of the ultrasonic waves transmitted by the reference oscillator 106 is generated and sent to the burst wave adjuster 4. The burst wave adjuster 4 outputs this reference signal for each constant number of pulses set by the burst wave setter 103 (hereinafter, this output signal is referred to as a burst wave). This burst wave is sent to the transmission delay circuit 3, is given a delay time for determining the deflection angle (directivity angle) and the convergence distance of the ultrasonic beam, and is supplied to the N-channel pulser circuit 2. The pulsar circuit 2 converts the supplied signal into a pulse wave for driving the ultrasonic transducer in the ultrasonic probe 1. The ultrasonic wave transmitted from the ultrasonic probe 1 is reflected inside the subject and is again received by the ultrasonic transducer of the ultrasonic probe 1. The received signal is amplified by the preamplifier 7 and then sent to the reception delay circuit 8 to be provided with the delay time for determining the deflection angle (directivity angle) and the convergence distance, similarly to the time of transmission. The delayed signal is added and synthesized by the adder 9 and sent to the mixer circuit 11-1 and the mixer circuit 11-2 and the detector 21 of the quadrature detection unit 17.

The detector 21 detects the signal from the adder 9 and sends it to the image processor 15. The image processing device 15 represents the tissue configuration of the cross section of the subject based on the signal from the detector 21 B
The mode image is obtained and displayed on the display device 16.

The reference correction circuit 102 produces a reference signal having a frequency designated by the reference setting device 101 from the reference signal sent from the reference oscillator 106, and sends it to the mixer circuit 11-1 and the mixer circuit 11-2. The mixer circuit 11-1 includes the reference corrector 102.
From the adder 9 and outputs it to the bandpass filter 12-1. On the other hand, the mixer circuit 11-2 includes the reference corrector 102.
The phase of the reference signal sent from the phase shifter 10
Then, the signal shifted by 90 ° and the signal from the adder 9 are multiplied and output to the bandpass filter 12-2. The band-pass filter 12-1 and the band-pass filter 12-2 remove the sum frequency component from each signal, extract only the difference frequency component, and send it to the frequency analyzer 13.

In order to perform frequency analysis by the frequency analyzer 13, it is necessary to continuously scan the same site and use a plurality of signals from the same site. For this reason, the frequency analyzer 13 stores a plurality of sent signals in a storage device in the frequency analyzer 13 and performs frequency analysis when a predetermined number of data are collected to obtain blood flow velocity information. .. The image processing device 15
Based on this blood flow velocity information, the CFM (color
flow mapping) image and sample volume setting device 105
The distribution of the blood flow velocity of a part of the B-mode image designated by is displayed as a graph to obtain a Doppler spectrum, which is displayed on the display device 16.

The quadrature detector 17 of the ultrasonic diagnostic apparatus described above.
Is a Doppler shift signal obtained by multiplying a reference signal sent from the reference corrector 102 by the detected ultrasonic echo information and extracting the frequency component of the difference through a bandpass filter. In order to efficiently extract this Doppler shift signal, it is preferable to make the center frequency of the frequency spectrum of the ultrasonic echo information equal to the frequency of the reference signal.

However, since the ultrasonic beam in the subject has a property of being more easily attenuated as the ultrasonic wave having a higher frequency, the ultrasonic probe 1 has a frequency distribution centered on the frequency f0 as shown in FIG. 9-a. When the ultrasonic beam that it has is transmitted to the inside of the subject, the high-frequency part is attenuated, so the spectrum of the ultrasonic echo detected is centered on the frequency fa lower than the frequency f0 as shown in FIG. 9-b. Becomes Especially in the deep part of the subject, high-frequency attenuation is large,
The center frequency of the spectrum shifts to the lower frequency side and becomes the frequency fb as shown in FIG. 9-c.

As described above, the center frequency of the spectrum of the ultrasonic echo deviates from the frequency f0 of the transmitted ultrasonic wave. Therefore, assuming that this frequency f0 is the frequency of the reference signal, the center frequency of the spectrum of the ultrasonic echo. Then, the reference frequency shifts, and the quadrature detection efficiency decreases. In particular, the ultrasonic echo in the deep portion has a large deviation from the frequency f0 of the transmitted ultrasonic wave, so that the quadrature detection efficiency decreases. Moreover, since the ultrasonic echoes in the deep part are attenuated and extremely weakened in the subject, if the quadrature detection efficiency is lowered, the image is significantly deteriorated.

In order to solve such a problem, in the conventional ultrasonic diagnostic apparatus, the operator sets the reference setting device 1
The reference frequency was switched by operating 01 to prevent the quadrature detection efficiency from decreasing.

Further, as a method for improving the image of the ultrasonic diagnostic apparatus, the reception level of the ultrasonic echo is increased by increasing the transmission level of the ultrasonic wave transmitted from the probe,
There is a method of improving the S / N ratio.

In order to raise the ultrasonic wave transmission level, the output level of the pulse wave supplied from the pulser circuit 2 to the ultrasonic probe 1 may be raised. However, the pulse wave contains many unnecessary frequency components such as DC components in addition to the necessary frequency components. Such a pulse wave is applied to the ultrasonic probe 1
, The unnecessary frequency components are consumed as heat in the ultrasonic probe 1, and only necessary signals are converted into ultrasonic waves and output. Therefore, if the output level of the pulse wave is increased in order to increase the transmission level of the ultrasonic wave, the level of the unnecessary frequency component included in the pulse wave also increases at the same time, which causes a problem that the heat generation of the ultrasonic probe 1 increases. ..

As a method for solving such a problem,
There is a method of increasing the burst wave number of ultrasonic waves to be transmitted. When the number of burst waves is increased, the level of the necessary frequency component rises and the level of the unnecessary part can be lowered, so that the ultrasonic wave transmission level can be raised while suppressing the heat generation of the probe.

However, when the burst wave number is increased,
Since the resolution decreases as the number of burst waves increases, the operator selects the optimum burst wave while observing the image and sets it by the burst wave setting device 103 to perform diagnosis.

[0014]

In the conventional ultrasonic diagnostic apparatus, both the shallow and deep ultrasonic echoes are subjected to quadrature detection at the same frequency designated by the reference setting device 101 to obtain a CFM image. For this reason, if the center frequency of the spectrum in the shallow portion is used as the reference frequency of the quadrature detection portion 17, the center frequency of the spectrum in the deep portion and the reference frequency of the quadrature detection portion 17 are displaced, and the detection efficiency in the deep portion is reduced. It was In particular, since the ultrasonic echo in the deep portion is weak and has a low S / N ratio, if the detection efficiency is lowered, the S / N ratio is further lowered, and noise such as color loss easily occurs in the image in the deep portion. Also, if the reference frequency of the quadrature detector is matched to the center frequency of the deep spectrum, the center frequency of the spectrum of the shallow part and the reference frequency of the quadrature detector will shift, so the detection efficiency in the shallow part will decrease, and There is a problem that noise such as color loss easily occurs in a partial image.

Further, when the Doppler spectrum is displayed by the conventional ultrasonic diagnostic apparatus, the range set by the sample volume setting unit 105 is scanned by the burst wave number set by the burst wave setting unit 103.

When measuring a deep Doppler spectrum, the error in the displayed Doppler spectrum increases because the attenuation inside the subject is large and the S / N ratio of the ultrasonic echo is not good. For this reason, it is better to increase the number of burst waves and improve the S / N ratio in the measurement of deep areas for diagnosis. Also,
Since the S / N ratio of ultrasonic echoes is relatively good in shallow diagnosis, it is better to reduce the number of burst waves in order to improve resolution.

In the conventional ultrasonic diagnostic apparatus, the operator must judge the setting of the burst wave number by looking at the image, and the burst wave setting device 103 must make the setting, which complicates the operation of the apparatus. ..

Therefore, it is an object of the present invention to provide an ultrasonic diagnostic apparatus which can display both the shallow and deep portions of an ultrasonic image with high image quality and high resolution and can simplify the operation of the apparatus.

[0019]

In order to solve the above problems, the present invention provides an ultrasonic probe for transmitting an ultrasonic wave, receiving an ultrasonic echo reflected and returned, and an ultrasonic probe from the ultrasonic probe. A transmission signal generating means for generating a transmission signal for transmitting a sound wave, and a quadrature detection reference signal generation means for generating a quadrature detection reference signal signal having a different frequency depending on the depth of the point where the received ultrasonic echo is reflected , Quadrature detection means for performing quadrature detection based on a reference signal for quadrature detection of the ultrasonic echo received by the ultrasonic probe and outputting it as a Doppler shift signal, and blood in the subject from the Doppler shift signal There is provided an ultrasonic diagnostic apparatus comprising: a frequency analysis unit for obtaining flow velocity information; and a display unit for displaying the blood flow velocity information.

[0020]

In the present invention, the transmission signal is generated by the transmission signal generating means and is transmitted to the ultrasonic probe to transmit the ultrasonic wave into the subject. The ultrasonic echo of the transmitted ultrasonic wave is received by the ultrasonic probe. The quadrature detection reference signal generating means generates a quadrature detection reference signal signal having a different frequency depending on the depth of the reflected ultrasonic echo. The quadrature detection means performs quadrature detection of the ultrasonic echo based on the reference signal for quadrature detection and outputs it as a Doppler shift signal. The frequency analysis means obtains blood flow velocity information in the subject from the Doppler shift signal and displays the blood flow velocity information on the display means.

[0021]

1 is a block diagram of the first embodiment of an ultrasonic diagnostic apparatus according to the present invention. The operation of each unit other than the reference corrector 5 and the blood flow velocity corrector 14 is the same as the configuration of the conventional device shown in FIG. Next, the blood flow velocity corrector 14 of the present embodiment will be described.

The blood flow velocity compensator 14 is a frequency analyzer 13.
Blood flow velocity information sent from the reference correction device 5
It is corrected based on the reference frequency information sent from the device and sent to the image processing device 15. Next, the operation of the reference corrector 5 of this embodiment will be described.

In the reference corrector 5 of this embodiment, the frequency of the reference signal is determined by the depth of the point where the ultrasonic wave transmitted from the ultrasonic probe 1 is reflected as an ultrasonic echo (hereinafter referred to as a reflection point). It is changing. The position of the reflection point is in the shallow portion immediately after transmitting the ultrasonic wave, and moves to the deep portion with the passage of time. Therefore, by changing the frequency of the reference signal with the passage of time, it is possible to generate the reference signal corresponding to the depth of the reflection point. Next, how the reference signal generated by the reference corrector 5 changes will be described.

The reference corrector 5 first generates a reference signal having a frequency equal to the frequency f0 of the reference signal sent from the reference oscillator 106, and shifts the frequency of this reference signal to the low frequency side with the passage of time. It outputs while making it. When the burst wave is received from the burst wave adjuster 4, the frequency of the reference signal is returned to the frequency f0 of the reference signal, and then the frequency is shifted again to the low frequency side and output.

By repeating this operation, the frequency of the reference signal changes like a saw with respect to the time axis. The states of the frequencies of the burst wave, the ultrasonic echo, and the reference signal at this time are shown in FIG. 2 (a), FIG. 2 (b), and FIG.
The time chart is shown in (c). At this time, the ultrasonic echo information from the point Ta to the point Tb becomes the ultrasonic echo information for one scanning line.

As shown in FIG. 2, at the point Ta immediately after receiving the burst wave, a reference signal having a frequency equal to the frequency f0 of the reference signal is generated, and the frequency of the reference signal linearly changes with time. Lower.
At this time, the frequency of the reference signal at point Tb immediately before receiving the next burst wave is fl.

Since the ultrasonic echo at the point Tb is the ultrasonic echo from the deepest part, the center frequency of the frequency spectrum of the ultrasonic echo at the deepest part is measured and this center frequency and fl are If they are equal to each other, quadrature detection can be efficiently performed.

Since the value of the frequency fl can be changed by changing the rate of frequency decrease (frequency shift coefficient), the center frequency of the frequency spectrum of the ultrasonic echo from the deepest part is measured beforehand, The frequency shift coefficient obtained from the measurement result is set in the reference adjuster 5 in advance. The reference adjuster 5 shifts the frequency of the reference signal based on the set frequency shift coefficient, and outputs the shifted frequency.

As a result, from the Ta point to the Tb point,
Since the reference signal that continuously changes the frequency from f0 to fl can be generated, the frequency of the reference signal can be always brought close to the center frequency of the frequency spectrum of the ultrasonic echo information, and the orthogonal detection of the signal can be efficiently performed. It can be carried out.

When this Doppler shift signal is sent to the frequency analyzer 13, the frequency analyzer 13 determines the blood flow velocity based on the equation 1 assuming that an ultrasonic wave having a frequency equal to the frequency fr of the reference signal is sent. ..

[0031]

[Equation 1] However, fd ... Doppler frequency fr ... Frequency of reference signal .theta .... Angle formed by ultrasonic beam and blood flow direction v ... Blood flow velocity, c ... Sound velocity. However, since the frequency of the ultrasonic wave actually transmitted from the ultrasonic probe 1 is the frequency f0 of the reference signal,
The actual blood flow velocity is obtained by Equation 2.

[0032]

[Equation 2]

Therefore, a deviation occurs between the blood flow velocity information sent from the frequency analyzer 13 and the actual blood flow velocity. In order to correct this shift, the correction can be performed by multiplying the right side of Expression 1 by the correction coefficient K expressed by Expression 3.

[0034]

[Equation 3]

Therefore, the blood flow velocity corrector 14 obtains the correction coefficient K from the frequency f0 of the reference signal and the frequency information of the reference signal sent from the reference corrector 5,
The blood flow velocity sent from the frequency analyzer 13 is corrected by multiplying this correction coefficient K and sent to the image processing device 15. The image processing device 15 obtains a CFM image based on the corrected image and displays it on the display device 16.

This makes it possible to eliminate the measurement error of the blood flow velocity that occurs when the orthogonal detection of the ultrasonic echo information is performed while changing the frequency of the reference signal. It is possible to perform quadrature detection efficiently by always approaching
An ultrasonic image with less noise can be displayed.

The blood flow velocity compensator 14 of this embodiment corrects the blood flow velocity based on the frequency information of the reference signal sent from the reference compensator 5. The correction value may be stored in the device 14 and synchronized with the burst wave sent from the burst wave adjuster 103, and the correction value may be changed over time.

Further, in the first embodiment, the frequency of the reference signal was linearly changed with the passage of time, but the relationship between the position of the reflection point and the center frequency of the frequency spectrum of the ultrasonic echo was measured beforehand. However, the frequency of the reference signal may be changed based on this measurement result. Since the center of the frequency spectrum of the ultrasonic echo changes depending on the frequency characteristics of the ultrasonic probe 1 and the measurement site, a reference corrector 5 having a plurality of characteristics is prepared and the characteristics can be switched by a switch or the like. Is also good.

This method of changing the reference frequency can be used not only when displaying a CFM image but also when measuring a Doppler spectrum. By using this method for the measurement of the Doppler spectrum, the error of the frequency component due to noise can be reduced and the accuracy of the obtained Doppler spectrum can be improved. Next, a second embodiment according to the present invention will be described.

In the measurement of the Doppler spectrum, there is a method of changing only the reference frequency as in the first embodiment, and a method of changing both the frequency of the ultrasonic beam to be transmitted and the reference frequency. FIG. 3 shows a configuration diagram of the second embodiment.

The sample volume designating unit 105 is for the operator to designate a portion for which the Doppler spectrum is to be measured as a sample volume. The position information of the sample volume designated by the sample volume designating unit 105 is sent to the image processing device 15 and the oscillation frequency calculator 18. The image processing device 15 synthesizes a graphic on the ultrasonic image and displays the sample volume. The oscillation frequency calculator 18 obtains the frequency at which the ultrasonic echo can be measured most efficiently at the designated sample volume position from the stored reference frequency information. The reference oscillator 6 generates a reference signal having a frequency equal to the obtained frequency and sends it to the burst wave adjuster 4 and the reference corrector 102. The reference corrector 102 converts this reference signal into a reference signal and sends it to the quadrature detection unit 17. Thereafter, blood flow velocity information is obtained in the same manner as in the device of the first embodiment, the image processing device 15 obtains a Doppler spectrum image, and the Doppler spectrum image is displayed on the display device 16. Next, the oscillation frequency calculator 1
The frequency information stored in 8 will be described.

FIG. 4A and FIG. 5A show the display device 16
3 is an example of the sample volume of the shallow portion and the deep portion displayed in FIG. FIG. 4B and FIG. 5B are bio-damping characteristics in a shallow portion and a deep portion, respectively. 4 (c) and 5 (c)
Are obtained by adding the frequency characteristics of the ultrasonic probe 1 to the biological attenuation characteristics of the shallow portion and the deep portion, respectively.

FIG. 6 shows an example of the frequency characteristic of the ultrasonic probe 1 (a in the figure) and the frequency characteristic of FIG. 4 (c) (b in the figure).
And the frequency characteristic (c in the figure) of FIG.

As can be seen from FIG. 4 (c), the ultrasonic echo signal obtained by transmitting the ultrasonic wave of frequency fb has the highest intensity in the shallow portion, and therefore the ultrasonic wave of frequency fb is the most intense. The ultrasonic echo can be detected efficiently. Further, as can be seen from FIG. 5C, the strength of the ultrasonic echo signal obtained by transmitting the ultrasonic wave of the frequency fc becomes the strongest in the deep portion, so that transmitting the ultrasonic wave of the frequency fc is the most efficient. Ultrasonic echo measurements can be made.

In this way, from the frequency characteristic of the ultrasonic probe 1 and the ultrasonic attenuation characteristic in the subject, the frequency at which the ultrasonic echo can be measured most efficiently at each depth point in the subject is obtained. It is stored in advance in the oscillator frequency calculator 18 as reference frequency information. As a result, the frequency of the ultrasonic wave emitted from the probe becomes the frequency at which the ultrasonic echo can be detected most efficiently at the position of the designated sample volume.
The ratio is improved and a highly accurate Doppler spectrum can be obtained. Next, a third embodiment according to the present invention will be described. FIG. 7 shows a block diagram of the third embodiment.

In the third embodiment, the position information of the sample volume designated by the operator using the sample volume setting unit 105 is sent to the image processing device 15, the burst wave calculator 19 and the reference calculator 20.

The burst wave number calculator 19 stores in advance the burst wave number at the time of measuring each sample volume position as burst wave number information. When the position information of the sample volume is sent from the sample volume setting unit 105, the burst wave number is obtained from the stored burst wave number information. Burst wave adjuster 4
Converts the reference signal sent from the reference oscillator 106 into a burst wave of the burst wave number obtained by the burst wave calculator 19 and outputs the burst wave.

For example, if the position of the sample volume is shallow in the burst wave calculator 19, the burst wave number is set to 1
Waves are stored so that the number of burst waves is 3 in the case of the deep part and 2 in the middle of the shallow part and the deep part, and when the operator specifies the position of the sample volume to the shallow part. Since scanning is performed with one burst wave, a Doppler spectrum with high resolution can be obtained. Further, when the position of the sample volume is designated in the deep portion, scanning is performed with three burst waves, so that it is possible to prevent the accuracy of the Doppler spectrum image from being deteriorated due to a decrease in the S / N ratio of the ultrasonic echo.

On the other hand, the reference calculator 20 stores beforehand the reference frequency at the time of measuring each sample volume position as the reference frequency number information.

When the reference volume information is sent from the sample volume setting unit 105, the reference calculator 20 obtains the reference frequency from the stored reference frequency information. The reference corrector 5 converts the reference signal sent from the reference oscillator 106 into a reference signal of the reference frequency obtained by the reference calculator 20, and outputs the reference signal.

By storing the center frequency of the frequency spectrum of the ultrasonic echo reflected and returned at each depth, which has been measured in advance, in the reference calculator 20, it is possible to store the center frequency more than in the first embodiment. Since the center frequency of the ultrasonic echo and the frequency of the reference signal can be brought close to each other, the quadrature detection efficiency can be further improved. In the conventional apparatus, the operator had to specify the burst wave number and the frequency of the reference signal in order to prevent the accuracy of the Doppler spectrum image from being lowered and the display from being disabled. However, according to the third embodiment, since the frequencies of the burst wave and the reference signal are set only by designating the sample volume,
The operation of the device can be reduced.

In the third embodiment, the bandwidth of ultrasonic waves transmitted from the ultrasonic probe 1 is wide with a small number of burst waves, and the bandwidth of ultrasonic waves becomes narrow as the number of burst waves increases. Therefore, the bandpass filter 12-based on the burst wave number obtained by the burst wave calculator 19
By changing the characteristics of 1 and the bandpass filter 12-2, it is possible to reduce noise and improve the S / N ratio of the Doppler shift signal. Incidentally. It is needless to say that the present invention is not limited to the above-mentioned embodiments and can be variously modified without departing from the spirit of the present invention.

For example, in the above embodiment, the electronic scanning type ultrasonic diagnostic apparatus for changing the scanning direction electronically has been described. However, the ultrasonic scanning apparatus for the mechanical scanning type for mechanically changing the scanning direction is used. You may implement.

[0054]

As described above in detail, according to the present invention, it is possible to display a shallow portion of an ultrasonic image as an image with high resolution and at the same time prevent deterioration of image quality in the deep portion and display with high image quality and high resolution. Moreover, it is possible to provide an ultrasonic diagnostic apparatus that can simplify the operation of the apparatus.

[Brief description of drawings]

FIG. 1 is a configuration diagram according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a time chart of burst waves, ultrasonic echoes, and reference frequencies.

FIG. 3 is a configuration diagram according to a second embodiment of the present invention.

FIG. 4 is a frequency characteristic diagram at a shallow portion.

FIG. 5 is a frequency characteristic diagram at a deep portion.

FIG. 6 is a characteristic diagram in which the attenuation characteristic in the subject is combined with the frequency characteristic of the ultrasonic probe.

FIG. 7 is a configuration diagram according to a third embodiment of the present invention.

FIG. 8 is a configuration diagram of a conventional ultrasonic diagnostic apparatus.

FIG. 9 is a diagram showing frequency distributions of ultrasonic echoes having different depths.

[Explanation of symbols]

 1 Ultrasonic probe 2 Pulser circuit 3 Delay circuit for transmission 4,104 Burst wave adjuster 5,102 Reference corrector 6,106 Reference oscillator 7 Preamplifier 8 Reception delay circuit 9 Adder 10 Phase shifter 11-1, 11- 2 mixer circuit 12-1, 12-2 bandpass filter 13 frequency analyzer 14 blood flow velocity corrector 15 image processing device 16 display device 17 quadrature detection unit 18 oscillation frequency calculator 19 burst wave calculator 20 reference calculator 21 detector 101 Reference Setting Device 103 Burst Wave Setting Device 105 Sample Volume Setting Device

Claims (4)

[Claims] 1. An ultrasonic probe that transmits an ultrasonic wave, receives an ultrasonic echo that is reflected and returned, and a transmission signal generator that generates a transmission signal for transmitting an ultrasonic wave from the ultrasonic probe. Means, a quadrature detection reference signal generating means for generating a quadrature detection reference signal having a different frequency depending on the depth of the point where the received ultrasonic echo is reflected, and the ultrasonic echo received by the ultrasonic probe Quadrature detection means for performing quadrature detection based on a reference signal for quadrature detection and outputting as a Doppler shift signal, frequency analysis means for obtaining blood flow velocity information in the subject from the Doppler shift signal, and the blood flow velocity An ultrasonic diagnostic apparatus comprising: display means for displaying information. 2. An ultrasonic probe that transmits an ultrasonic wave, receives an ultrasonic echo that is reflected and returned, and a transmission signal generation that generates a transmission signal for transmitting an ultrasonic wave from the ultrasonic probe. Means, a part designating means for designating a specific part in the subject, and a frequency of a reference signal for quadrature detection for performing quadrature detection, which is obtained based on the position of the specific part, and is output as frequency information for quadrature detection A means for obtaining a reference frequency, a quadrature detection reference signal generating means for outputting a quadrature detection reference signal in which the frequency is changed based on the frequency information, and a quadrature by multiplying the received signal and the quadrature detection reference signal Quadrature detection means for detecting and outputting as a Doppler shift signal, frequency analysis means for obtaining blood flow velocity information in the subject from the Doppler shift signal, and displaying the blood flow velocity information. An ultrasonic diagnostic apparatus comprising: a display unit shown. 3. The ultrasonic diagnostic apparatus according to claim 2, wherein the transmission signal generating means changes the frequency of the transmission signal based on the position of the specific portion. 4. A site designating unit for designating a specific site within a subject, an ultrasonic probe for transmitting an ultrasonic wave and receiving an ultrasonic echo reflected and returned, and based on the site information. Burst wave number calculation means for obtaining the burst wave number of ultrasonic waves to be transmitted, transmission signal generation means for generating a transmission signal for transmitting ultrasonic waves of the burst wave number from the ultrasonic probe, and quadrature detection reference signal A quadrature detection reference signal generating means for generating, the quadrature detection means for performing the quadrature detection based on the quadrature detection reference signal the ultrasonic echo received by the ultrasonic probe, and outputting as a Doppler shift signal, An ultrasonic diagnostic apparatus comprising: a frequency analysis unit for obtaining blood flow velocity information in the subject from a Doppler shift signal; and a display unit for displaying the blood flow velocity information.