JP3510025B2 - Ultrasound imaging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] The present invention relates to an ultrasonic imaging method.
And devices, ultrasonic probes and ultrasonic contrast agents
I do. More specifically, it has nonlinear ultrasonic reflection characteristics
Ultrasound imaging method and apparatus for echo source
An ultrasonic probe and an ultrasonic contrast agent. [0002] 2. Description of the Related Art In recent years, the resilience of microbubbles to ultrasonic waves
Second harmonic imaging method using nonlinear response studied
Is being done. In addition, soluble microbal
Development of a contrast agent mainly composed of micro balloons
Have been. [0003] The second harmonic imaging method involves the use of a contrast medium.
Microbubbles are illuminated by their resonant nonlinear response.
Generating an echo including a second harmonic of the transmitted ultrasonic wave
Is used. This echo is about 1 of the Doppler signal.
It has a sensitivity of 00 times. In the received second harmonic echo
An image of the contrast injection site is formed based on the
In addition, based on the time course of the concentration of the contrast agent,
Noh is measured. [0004] [Problems to be solved by the invention] (1) In an ultrasonic imaging apparatus, a focused wavefront of an ultrasonic wave is
Non-linear effects at the focal point are unavoidable due to transmission.
Near the focal point and beyond, the transmitted pulse itself is
And have a large amount of second harmonic components. Therefore,
As a result, second harmonic echoes are generated from sources other than the contrast agent
Indistinguishable from echo from contrast agents. [0005] Due to the nonlinear action of such transmitted pulses,
To reduce interference, set the transmission level to normal
Must be reduced to a fraction of the level used for the image
The magnitude of the secondary effect we want to observe is the transmission level
Lowering the transmission level is ecological because it is proportional to the square of
-It has a double disadvantage for reception. (2) To the transmission signal itself for transmitting ultrasonic waves
Also conflicts with the second harmonic or the reception frequency band of the observation system
May contain such frequency components.
-Is also indistinguishable from contrast agent echoes. [0007] To prevent this, each transducer of the ultrasonic probe is used.
A linear amplifier for transmission (linear amplifie
r) or use a strict low-pass filter to
It is necessary to avoid such frequency components.
You. However, the electronic scanning type ultrasonic probe has
The higher the performance, the more transducer elements are used
Is transmitted every such many transducer elements
The use of linear amplifiers and low-pass filters for
Large obstacles to simplification, miniaturization, and low power consumption
Becomes (3) In imaging by the second harmonic,
Since it transmits a fundamental wave and receives an echo of twice the frequency,
Therefore, a broadband ultrasonic probe is required. Fractional band
When the width is secured, the upper and lower frequency ratio is 130% to 1
It requires as much as 50% of an ultra-wideband ultrasound probe. this
Of the ultrasonic probe used for ordinary ultrasonic imaging
Since the relative bandwidth is about 70%,
I can not do such a thing. Ultrasonic probe with fractional bandwidth over 100%
It is possible to design the sound element,
There is a great deal of difficulty in realizing this because of the need for a matching layer.
With difficulty. (4) Resonance frequency f of microballoon₀Is
Radius r₀Against [0011] (Equation 1) There is a relationship as follows. Micro balloon
The two harmonics are sent back around this resonance frequency
Is not very wide frequency band. Because of this, the microphone
If there is a distribution in the particle size of the balloon, only part of it is non-linear
It does not contribute to the generation of shape echo and is inefficient. (5) Applying a microballoon contrast agent to the subject
Inject and observe the function of the tissue of interest from the time course of its concentration
When measuring, the same part continuously for a predetermined time
Must continue to capture. However, the movement of body tissues
The target area is easy to escape due to
Traces are not easy. The present invention has been made in order to solve the above problems.
The purpose was to achieve nonlinearity by the second harmonic.
Ultrasonic imaging method and apparatus capable of efficiently performing ultrasonic imaging
And realizing an ultrasonic probe and an ultrasonic contrast agent
It is. [0015] [Means for Solving the Problems] (1) The first invention for solving the problem is that the subject
Ultrasound that transmits sound waves and uses the second harmonic component of the echo
In the acoustic wave imaging method, an ultrasonic wave of a first intensity
A second intensity supersonic substantially 1 / k times the first intensity;
And an ultrasonic wave transmitted alternately and at the first intensity.
Based on the echo based on the
And the supersonic transmitted at the second intensity.
A signal substantially equal to k times the wave-based echo reception signal and
An echo reception signal based on the ultrasonic wave transmitted at the first intensity
Ultrasound imaging method characterized by using a signal of difference from
Is the law. In the first invention for solving the problems,
Therefore, it is preferable to set k to 2 since signal processing becomes easy.
New In this case, the transmission at the second intensity is performed twice,
By adding the two received signals based on that,
Qualitatively doubling is preferable in terms of reducing noise. According to a first aspect of the invention for solving the problem,
If the ultrasonic wave is transmitted at two different intensities,
The difference between the two types of echo reception signals obtained
Filter from the nonlinear echo source, etc.
Ultrasound imaging method that can extract without using
Can appear. (2) Second invention for solving the problem
Transmits the ultrasonic wave to the subject and generates the second harmonic of the echo.
In the ultrasonic imaging method using the
The ultrasonic wave having a phase differs from the first phase by substantially 180 °.
And an ultrasonic wave having a second phase,
Echo based on ultrasound transmitted in phase and said second phase
Receiving an echo based on the ultrasonic wave transmitted in
The echo received signal based on the ultrasonic wave transmitted at the phase of
An echo reception signal based on the ultrasonic wave transmitted in the second phase;
Ultrasound imaging method using a sum signal of signals
It is. According to a second aspect of the present invention for solving the problems,
And the first phase is substantially 90 ° out of phase with the first phase.
A fourth phase substantially 270 ° out of phase with the ultrasonic wave of phase 3
And the ultrasonic waves having the phases of
Signal of the sum of the echo reception signals for the ultrasonic wave transmitted in the phase
Obtain the Doppler signal from the nonlinear echo source
It is preferred in that respect. According to a second aspect of the invention for solving the problem,
For example, ultrasonic waves are transmitted in multiple phases and
To obtain the sum of multiple received echo signals
Therefore, the echo from the nonlinear echo source is
Ultrasound imaging method that can be extracted without
Wear. (3) Third invention for solving the problem
Transmits the ultrasonic wave to the subject and generates the second harmonic of the echo.
In the ultrasonic imaging method using the
A signal having a frequency higher by a predetermined frequency than the fundamental frequency
Transmission combining a signal with a frequency lower by the predetermined frequency
Transmitting ultrasonic waves based on signals to a subject.
This is an ultrasonic imaging method. According to a third aspect of the invention for solving the problem,
If the two frequencies of the transmitted ultrasonic wave are in the nonlinear echo source,
Mixing, the frequency is twice the fundamental frequency.
An ultrasonic imaging method that can obtain echo signals is realized.
Wear. (4) Fourth invention for solving the problem
Transmits an ultrasonic wave to a subject and, based on the transmitted ultrasonic wave,
Receiving the echo, and converting the echo received signal to its fundamental wave.
Of the sum of the signal shifted by half wavelength and the echo reception signal
An ultrasonic imaging method characterized in that a signal is obtained. According to a fourth aspect of the invention for solving the problem,
For example, by adding the half-wave shift of the fundamental wave,
Which can eliminate the second harmonic component by eliminating
An imaging method can be realized. (5) Fifth invention for solving the problem
Transmits the ultrasonic wave to the subject and generates the second harmonic of the echo.
In the ultrasonic imaging method using the minute, the ultrasonic beam
A pair of vibrators related to the formation;
Of the transmitted beam formed by the ultrasonic waves transmitted from the
The phase at which the second harmonic components of the dynamic frequency cancel each other out
Drive with a pair of transmission signals so that
In the receiving beam formed by the reception signals of the pair of transducers,
The second harmonic components of the dynamic frequency have mutually reinforcing phases
Characterized by adding a pair of received signals as described above
This is a wave imaging method. According to a fifth aspect of the present invention for solving the problems,
For example, a pair of transducers involved in the formation of an ultrasonic beam
Driven by a pair of transmission signals and
Since a pair of received signals is added, the transmission beam
Does not include the second harmonic component, and the received beam
An ultrasonic imaging method including only the second harmonic component is realized.
Can be (6) Sixth invention for solving the problem
Transmits the ultrasonic wave to the subject and generates the second harmonic of the echo.
In the ultrasonic imaging method using the minute,
Displacement of point of interest in subject by scanning three-dimensionally with wave beam
And track the region of interest based on the displacement of the point of interest.
An ultrasonic imaging method characterized in that: According to a sixth aspect of the present invention for solving the problems,
And, at least once, three-dimensionally scan the inside of the subject precisely.
A three-dimensional image based on this precise scanning is obtained, and the
And scans only the point of interest based on the displacement of the point of interest.
And transforming the three-dimensional image in real time.
Is preferred in that According to a sixth aspect of the present invention for solving the problems,
Tracking the region of interest based on the displacement of the point of interest
The region of interest whose features are not clear
Can be tracked and accurate measurements using contrast agents can be performed.
The ultrasonic imaging method can be realized. (7) Seventh invention for solving the problem
Transmits the ultrasonic wave to the subject and generates the second harmonic of the echo.
In an ultrasonic imaging apparatus utilizing the
The ultrasonic wave of high intensity and the first ultrasonic wave having substantially 1 / k times the first intensity
A transmitting means for transmitting ultrasonic waves having an intensity of 2 alternately;
An echo based on the ultrasonic wave transmitted at the first intensity and the second
Receiving an echo based on ultrasonic waves transmitted at
Transmitting means and an ultrasonic wave transmitted at the second intensity.
A signal obtained by substantially multiplying a received signal by k and said first intensity
Difference signal from echo received signal based on ultrasonic wave transmitted by
And an arithmetic means for calculating
An imaging device. According to a seventh aspect of the present invention for solving the problems,
Therefore, it is preferable to set k to 2 since signal processing becomes easy.
New In this case, the transmission at the second intensity is performed twice,
By adding the two received signals based on that,
Qualitatively doubling is preferable in terms of reducing noise. According to a seventh aspect of the present invention for solving the problems,
If the ultrasonic wave is transmitted at two different intensities,
The difference between the two types of echo reception signals obtained
Filter from the nonlinear echo source, etc.
Ultrasound imaging device that can extract without using
Can appear. (8) Eighth invention for solving the problem
Transmits the ultrasonic wave to the subject and generates the second harmonic of the echo.
In an ultrasonic imaging apparatus utilizing the
The ultrasonic wave having a phase differs from the first phase by substantially 180 °.
Transmitting means for alternately transmitting ultrasonic waves having a second phase
And an echo based on the ultrasonic wave transmitted in the first phase.
And an echo based on the ultrasonic wave transmitted in the second phase.
Receiving means for transmitting the ultrasonic wave transmitted in the first phase.
Based echo received signal and supersonic transmitted in said second phase
An operator who calculates the sum signal of the echo received signal based on the wave
And an ultrasonic imaging device comprising:
You. According to an eighth aspect of the present invention for solving the problems,
And the first phase is substantially 90 ° out of phase with the first phase.
A fourth phase substantially 270 ° out of phase with the ultrasonic wave of phase 3
And the ultrasonic waves having the phases of
Signal of the sum of the echo reception signals for the ultrasonic wave transmitted in the phase
Obtain the Doppler signal from the nonlinear echo source
It is preferred in that respect. According to an eighth aspect of the present invention for solving the problems,
For example, ultrasonic waves are transmitted in multiple phases and
To obtain the sum of multiple received echo signals
Therefore, the echo from the nonlinear echo source is
Ultrasound imaging device that can be extracted without
Wear. (9) Ninth invention for solving the problem
Transmits the ultrasonic wave to the subject and generates the second harmonic of the echo.
In ultrasonic imaging devices that use
A signal having a frequency higher by a predetermined frequency than the fundamental frequency
Transmission combining a signal with a frequency lower by the predetermined frequency
Equipped with transmitting means for transmitting ultrasonic waves based on the signal to the subject
An ultrasonic imaging apparatus characterized in that: According to a ninth invention for solving the problems,
If the two frequencies of the transmitted ultrasonic wave are in the nonlinear echo source,
Mixing, the frequency is twice the fundamental frequency.
An ultrasonic imaging device that can obtain echo signals is realized.
Wear. (10) Tenth aspect for solving the problem
Akira comprises: a transmitting means for transmitting an ultrasonic wave to a subject;
Receiving means for receiving an echo based on the obtained ultrasonic wave,
A signal obtained by shifting the echo reception signal by half the wavelength of its fundamental wave
Calculating means for obtaining a signal of the sum with the echo reception signal.
An ultrasonic imaging apparatus comprising: According to a tenth invention for solving the problems,
For example, by adding the half-wave shift of the fundamental wave,
Which can eliminate the second harmonic component by eliminating
An imaging device can be realized. (11) An eleventh aspect for solving the problem
Akira sends an ultrasonic wave to the subject and the second harmonic of the echo
In an ultrasonic imaging apparatus using components, an ultrasonic beam
A pair of oscillators involved in the formation of
Of the transmitted beam formed by the ultrasonic waves transmitted from the
The phase at which the second harmonic components of the dynamic frequency cancel each other out
Driving means for driving with a pair of transmission signals so that
In the receiving beam formed by the reception signals of a pair of transducers
The second harmonic component of the vibration frequency has a phase that reinforces each other.
Adding means for adding a pair of received signals so that
An ultrasonic imaging apparatus characterized in that: According to the eleventh invention for solving the problems,
For example, a pair of transducers involved in the formation of an ultrasonic beam
Driven by a pair of transmission signals and
Since a pair of received signals is added, the transmission beam
Does not include the second harmonic component, and the received beam
To realize an ultrasonic imaging apparatus including only the second harmonic component
Can be (12) A twelfth aspect for solving the problem
Akira sends an ultrasonic wave to the subject and the second harmonic of the echo
In an ultrasonic imaging device that uses components,
Scanning means for three-dimensionally scanning with an acoustic wave beam;
Displacement calculating means for calculating the displacement of the point of interest in the subject from the received signal
Tracking a region of interest based on a step and a displacement of the point of interest
Ultrasound imaging apparatus comprising tracking means
It is. In a twelfth invention for solving the problems,
And, at least once, three-dimensionally scan the inside of the subject precisely.
A three-dimensional image based on this precise scanning is obtained, and the
And scans only the point of interest based on the displacement of the point of interest.
And transforming the three-dimensional image in real time.
Is preferred in that According to a twelfth invention for solving the problems,
Tracking the region of interest based on the displacement of the point of interest
The region of interest whose features are not clear
Can be tracked and accurate measurements using contrast agents can be performed.
A realizable ultrasonic imaging device can be realized. (13) A thirteenth aspect for solving the problem
The invention has a first aspect having a frequency band including a first frequency.
A vibrator and a frequency including a frequency twice as high as the first frequency
A second vibrator having several bands.
Ultrasonic probe. In the eleventh invention for solving the problems,
The first vibrator and the second vibrator are alternately
Arrangement is preferable in terms of homogenizing the transducer array.
No. According to a thirteenth invention for solving the problems,
An oscillator array in which the first oscillators are connected.
And an array in which the second vibrator is connected.
Is preferable in that the production becomes easy. According to a thirteenth invention for solving the problems,
Then, by providing the first vibrator and the second vibrator,
And f₀And 2f_oProbe with two different frequencies
Can be realized. (14) Fourteenth aspect for solving the problem
Ming said that the particle size distribution of soluble microballoons is substantially
An ultrasonic contrast agent characterized by being within 1: 2.
You. According to the fourteenth invention for solving the problems,
Excitation ultrasound because the particle size distribution of the black balloon was 1: 2
Ultrasound Contrast Agent Efficiently Generates Nonlinear Echoes for Light
Can be realized. [0049] BRIEF DESCRIPTION OF THE DRAWINGS FIG.
The embodiment will be described in detail. (1) Overall configuration FIG. 1 shows a block diagram of the ultrasonic diagnostic apparatus. This device is a book
It is one embodiment of the invention. Depending on the configuration of this device,
1 shows an embodiment of the apparatus of the present invention. Ma
In addition, the operation of the present apparatus enables the implementation of the method of the present invention.
One form is shown. In FIG. 1, an ultrasonic probe 1 is shown.
To send an ultrasonic beam to an unexamined subject
These echoes are received. Ultrasonic probe 1
1 is an example of an embodiment of an ultrasonic probe according to the present invention.
You. The subject is made of a soluble microballoon
A contrast agent is injected, and ultrasound imaging is performed based on the contrast agent.
Is The contrast agent will be described later. The ultrasonic probe 1 has different frequency bands 2
It has different types of transducer elements. One oscillator d
The resonance frequency of the micro balloon is in the frequency band of the element.
And the frequency band of the other transducer element
Twice that frequency is included. About ultrasonic probe 1
Will be explained later. The transmitting / receiving section 2 drives the ultrasonic probe 1
While transmitting the ultrasonic beam, the ultrasonic probe 1
This is for receiving the echo reception signal. Ultrasonic inside the subject
It is scanned by the sound rays formed by the wave beam. Transceiver
2 is an ultrasonic probe 1 which is a transmission signal of a predetermined fundamental frequency.
Drive and extract the second harmonic component from the received signal.
It is configured to issue. The transmitting / receiving unit 2 according to the present invention
Example of Embodiment of Wave Transmitting Means, Receiving Means, and Scanning Means
It is. The transmitting / receiving unit 2 will be described later. The echo signal received by the transmitting / receiving section 2 is
B mode image data is created by
You. The B mode processing unit 3 switches the operation to the M mode image.
Image data can also be created. The echo signal received by the transmitting / receiving unit 2
Is processed by the Doppler processing unit 4 and is a Doppler spectrum day.
Data is created. Pulsed Doppler mode for Doppler processing
There is a CW (continuous wave) Doppler mode. The echo signal received by the transmitting / receiving unit 2
Is a color Doppler image processed by the color Doppler processing unit 5
Data is created. Color Doppler images are CFM (color
 flowmapping) Also called an image. The digital scan converter section 6
B-mode image data, Doppler spectrum data and
Video signal scanned and converted for color Doppler image data
Is input to the display unit 7 and the recording unit 8. The display unit 7 displays an image based on a video input signal.
To display. The recording unit 8 records the video input signal.
Things. The recording unit 8 is, for example, a video tape recorder.
A coder (video taperecorder) is used. The data processing unit 9 sends and receives signals to and from each of the above units.
And performs data processing to control the operation of each unit.
The data processing unit 9 also performs a temporal change in the density of the contrast agent image.
It also measures organizational functions based on At that time, pay attention
Even if the part is displaced due to body movement, etc.
It is to be traced. The data processing unit 9 according to the present invention
Of the embodiment of the displacement detecting means and the tracking means for
is there. Later on such displacement detection and tracking will be revised.
I will explain. The data processing section 9 has a computer and a data processing section.
It is composed of a management program. Data processing unit 9
It reads and writes data from and to the storage unit 10.
The storage unit 10 stores three-dimensional image data described later.
The operation unit 11 is operated by the operator and is transmitted to the data processing unit 9.
It provides an input signal and a command signal. (2) Contrast agent The reflection intensity at the fundamental wave as a general contrast agent is micro
The larger the diameter of the balloon, the larger. Therefore, the peripheral blood system
The center of particle size distribution is around several μm, the critical dimension at which embolism occurs at
It is said. In this case, the optimal irradiation frequency of the ultrasonic wave is 2-1.
MHz or lower, and the
The frequency of the second harmonic is the frequency of the observation system in ordinary ultrasonic imaging.
Enter the frequency band. Therefore, the normal observation system
Using the observation system in ultrasonic imaging, transmit waves to normal ultrasonic
It would be better to perform at half the frequency of wave imaging. If there is a distribution in the particle size of the microballoon,
Efficiency is poor because only a part of
Micro-bars with narrow particle size distribution (sharp distribution curve)
I will use runes. The particle size distribution is the minimum diameter
The ratio of the maximum value to the maximum value is within 1: 2.
It is preferable from the viewpoint of increasing the generation efficiency. Also narrow the particle size distribution
Then, the frequency distribution of the nonlinear echo narrows and the filter
This is very convenient for separation. (3) Ultrasonic probe FIG. 2 is a sectional view showing an example of the embodiment of the ultrasonic probe 1.
Indicated by In FIG. 2, the transducer array 101 is
It is provided on the locking material 102. In addition, acoustic matching
Illustration of layers and the like is omitted. The transducer array 101
Two types of transducer elements a and b are alternately arranged
It is constituted by. The vibrator elements a and b are staggered.
3, only the transducer element a as shown in FIG.
And the array with only transducer element b
You may arrange in a line. In the configuration of FIG. 2, two types of transducer elements are used.
This is preferred because it is uniformly distributed over the entire length of the array.
The configuration of FIG. 3 is preferable in that the array can be easily manufactured. vibration
Element a and element b are examples
For example, 64 channels are provided. One channel is
One transducer element may be used.
May be used. The transducer elements a and b are different from each other.
It has a different frequency band. Examples of those frequency bands
As shown in FIG. In FIG. 4, Ba represents a transducer element a.
Bb is the frequency band of the transducer element b
It is. The vicinity of the lower limit of the frequency band Ba is a microvalve.
Resonance frequency f₀(Eg 2MHz)
Swelling. The second harmonic is near the upper limit of the frequency band Bb.
Wave frequency 2f₀(For example, 4 MHz)
Has become. Each of the bands Ba and Bb has a fractional bandwidth.
For example, it is 70%. Thereby, the band Ba
The high band and the low band of the band Bb overlap, and the common band Bc
It is formed. The ultrasonic wave is transmitted by the transducer element a.
Performed in band Ba by an array of 64 channels
Wave reception is performed for 64 channels formed by the vibrator element b.
Performed in band Bb by the array. This allows the frequency
Number f₀The micro balloon is excited by
Second harmonic 2f due to resonance of black balloon₀Echo of
Received. That is, a single ultrasonic probe
Both the micro balloon excitation frequency and its second harmonic
Can be handled. Note that when transmitting and receiving waves,
Ultrasonic beam forming is performed by the receiving unit 2
Needless to say. The echo reception signal depends on the operation mode.
B-mode image, Doppler spectrum image, CFM
Used for forming images and the like. It should be noted that ordinary microballoons are not used.
When performing imaging, only the array of transducer elements a is used.
Transmission / reception, transmission / reception only by the array of transducer elements b
Wave and array of transducer element a and transducer element
Transmission and reception using the array of
it can. Transmission by only the array of transducer elements a
When receiving waves, 64 channels with a frequency band of Ba
Can be used as a probe. Oscillator element
Frequency when transmitting and receiving only the array of
Use as a probe of 64 channels with Bb bandwidth
be able to. Array of transducer elements a and transducer
When the array of element b is used simultaneously, the frequency
Used as a 128 channel probe with a Bc band
Can be Another embodiment of the ultrasonic probe 1 is shown in FIG.
And FIG. FIG. 5 is a plan view, and FIG. 6 is a sectional view taken along line AA.
It is. 5 and 6, a disk-shaped vibrator array is shown.
A 103 is provided on the backing material 104. vibration
The transducer array 103 includes two types of transducer elements a and b.
It is constituted by. The vibrator element a and the vibrator element b
Is formed as a fan-shaped diaphragm, and the backing material 104
A disk-shaped array that is staggered on the whole
Make up. Making a disk-shaped array concave is super sound
This is preferable in that the wave beam is focused. The number of transducer elements is, for example, an even number as a whole.
(2,4,6,8, ...) used, vibrator element
a and b are assigned to half each. In that case, each element
If the same shape is used,
2 sets using all of the cut transducer elements without waste
Probe can be made, and material utilization is high.
You. Another form of the transducer element arrangement is shown in FIGS.
As shown in FIG. The arrangement shown in FIG. 7 is a stripe-shaped vibrator.
Elements a and b are alternately arranged. This distribution
The rows are preferred in that they increase the density of the transducer elements. Figure
The arrangement shown in FIG. 8 is composed of dice-shaped vibrator elements a and b.
They are arranged in a mosaic (checkered pattern). This distribution
Rows are preferred to further increase the density of transducer elements
No. The arrangement shown in FIG. 9 is an annular transducer element.
A disk-shaped vibrator element b is concentrically disposed inside
It is arranged. Note that the relationship between the two
The transducer element b is formed in an annular shape, and the transducer element a is formed in a circle.
It may be plate-shaped. This array is preferred because of its simple configuration.
No. The vibrator element a has a vibration frequency f₀With
The vibrator element b has a vibration frequency 2f
₀It has. Using micro-balloon contrast agent
The ultrasonic wave is transmitted by the transducer element a.
The wave reception is performed by the vibrator element b. Ma
If you do not use a micro balloon contrast agent,
Transmission and reception using either or both of the components a and b
It can be performed. The ultrasonic probe shown in FIGS.
It is suitable for use as a probe for a laser. Of course it
It is not limited to
Probe for compound or probe for compound scan
It may be used as a power supply. (4) Transceiver FIG. 10 is a block diagram showing an example of an embodiment of the transmission / reception unit 2.
Are shown for one channel. A similar configuration is used for each channel.
It is provided for each channel. In FIG. 10, a transmission signal generator
The transmission signal generated from 201 is amplified by transmitter 202.
Is filtered by the filter 203, and the transmission / reception switching
Given to the transducer element 100 through the switch 204
And transmitted as ultrasonic waves. In addition,
At the time of transmission, a beamformer (not shown)
Steering or focusing of transmission beam
Is Echo received by transducer element 100
The signal is transmitted to the receiver 205 through the transmission / reception switch 204.
, Is amplified by the receiver 205, and is filtered by the filter 206.
Filtered by the A / D converter 207
/ Digital conversion and stored in the memory 208. What
When receiving, use a beamformer (not shown).
Is the receiving beam steering or focusing
Is performed. Transmission signal generated from transmission signal generator 201
The frequency, amplitude, phase, duration, etc. of the signal
09 is controlled. Tx / Rx switching
Switching of switch 204 and operation timing of A / D converter 207
Is also controlled by the controller 209. The controller 209 is, for example, an MPU (micro
 processor unit). Controller 2
09 indicates the data stored in the memory 208.
Then, an operation described later is performed. Controller 209 is a book
It is an example of an embodiment of a calculation means in the invention. For switching output amplitude of transmission signal generator 201
More than 100% amplitude transmission and 50% amplitude for the same sound ray
Are alternately repeated, and 2 corresponding to those transmissions
The types of received signals are stored in the memory 208. The transmission amplitude can be switched for each sound ray.
Well, and do it every frame of ultrasonic scanning
Is also good. The time difference between the two types of transmission is different for each sound ray.
It is preferable because it has few points. Switching of amplitude is performed every frame
This is preferable in that the frequency can be reduced. The controller 209 receives a reception signal of the same sound ray.
For each signal, double the received signal by 50% transmission to 100%
The difference between the received signal and the received signal is determined as one received signal.
You. If all echo sources in the subject are linear reflection sources
Return an echo proportional to the transmission amplitude.
When transmitting, the reception signal by 100% transmission and 50% transmission
All the frequency components are the same
The same value. Therefore, by calculating the difference between the two,
In addition to the fundamental component of the transmitted wave,
Higher harmonic components are also canceled out. On the other hand, the micro-balloon
When there is a contrast agent, the nonlinear components in the echo are transmitted.
Because it is proportional to the square of the wave amplitude, 100% transmission
Between the signal and the signal received by doubling 50% transmission
Are different. Therefore, to find the difference between the two
Getting more echoes from such non-linear echo sources
Can be. That is, a signal for extracting the second harmonic.
Eco-friendly from a non-linear echo source without using filters
-Can only get. In addition, take the second harmonic
Even if you use a filter to get out,
In addition, nonlinear components that are originally included in the
Minutes can be removed. Therefore, the transmitter 202 and the receiver 2
It is necessary to use something with particularly good linearity as 05
Not the one used for normal ultrasound imaging
May be used. Also, the filters 203 and 206 are usually
What is used for ultrasonic imaging of may be used as it is,
Strict low-pass and second harmonic filters, respectively
It doesn't have to be rutha. That is, the second harmonic
No special transmission / reception mechanism is required for acoustic imaging. Note that the transmission amplitude is limited to 100% and 50%.
Instead, it may be a predetermined level and a half thereof. Also, 1
/ 2 (k> 1)
May be multiplied by k. Also, the received signal by the half-level transmission is
Instead of doubling, transmission and reception at 1/2 level are the same sound line
To the received signal obtained by performing the operation twice
good. This method is based on the averaging effect of noise by addition.
This is preferable in that a received signal with less noise can be obtained. FIG. 11 shows another embodiment of the transmission / reception unit 2.
An example block diagram is shown for one channel. FIG.
In FIG. 10, the same parts as those in FIG.
Description is omitted. In FIG. 11, filters 206 and A
A demodulator 210 is inserted between the / D converter 207 and
As a result, the received signal is shifted to the frequency 2f₀Demodulate with
It has become. Generation of transmission signal by controller 209
By switching the output phase of the device 201, the same sound ray
And the frequency f₀0 ° phase transmission and 180 ° phase
Transmission is repeated alternately. The switching of the transmission phase is super
The scanning may be performed in units of frames of the sound wave scanning. Two types of reception signals corresponding to those transmissions
Is 2f by the demodulator 210.₀A / D converter 2
At 07, it is converted to a digital signal and stored in the memory 208.
Is done. The controller 209 controls the transmission for the 0 ° phase transmission.
Between the received signal and the received signal for the 180 ° phase transmission.
The sum is obtained and used as one received signal. When the received signal is 2f₀Demodulated by
In the demodulated signal, the fundamental frequency component is 0
Received signal corresponding to the transmission of 180 ° phase and transmission of 180 ° phase
Since the received signals corresponding to have opposite polarities, the sum is
Offset by On the other hand, the second harmonic component is
Number f₀180 ° phase shift is 360 ° phase shift
, The 0 ° phase transmission in the demodulated signal
And the reception signal corresponding to the 180 ° phase transmission.
The received signals have the same polarity and are doubled by taking the sum. You
That is, the fundamental frequency component of the echo is canceled and the second harmonic
Because of the strength of each other, the second
An echo of only harmonics can be obtained. The above situation
As shown in FIG. FIG. 13 shows a different point of view.
A constant repetition period PRT (pulse repetition tim)
e) frequency f generated in₀Fourier transform of the pulse signal of
Is as shown in FIG. 14, and the frequency f₀Part frequency
Spectrum and frequency 2f₀It is just like that of the part
Line up in matching order. Here, the spectrum interval is P
RF (pulse repetition frequency). PRF is P
It is the reciprocal of RT. On the other hand, as in the present embodiment,
When the phase of the pulse is inverted (Fig. 15), its frequency spectrum
The tram is as shown in FIG. That is, the second harmonic
Wave 2f₀Is the odd order of the PRF and the fundamental frequency f₀Rank
There is no spectrum in the location. However, a Doppler shift occurs in the fundamental frequency component.
In some cases, the amount is not canceled and remains as a Doppler signal.
Therefore, this embodiment extracts the second harmonic component for the B mode.
Frequency components for Doppler mode
It can also be applied to the use of extracting the Doppler shift component of. When the CW Doppler mode is performed,
As shown in FIG. 7, the frequency f₀Ream
A continuation wave is generated, and its phase is set to 0 ° and 180
Switch to °. At this time, prevent aliasing.
Therefore, 1/2 of the reciprocal of the phase switching period (equivalent to PRF) is
Must be much larger than the Doppler shift to be detected
You. As another example of the transmission embodiment, the basic
Wave number f₀The transmission signal of the same sound line by changing the phase by 90 °
There is also a method of transmitting waves four times each. That is, 0 °, 90
°, 180 ° and 270 ° in sequence
It is. Then, each echo reception signal is converted to 2f₀
, Demodulate and digitize and store in the memory 208.
Is used to add all four received signals. In this case, the fundamental frequency f₀90 ° is the second
Since it corresponds to 180 ° of the harmonic, all four received signals are added.
Calculates the second harmonic component in addition to the fundamental frequency component.
Negative minutes. This situation is shown in FIG. At this time, the Doppler shift occurs to the second harmonic component.
If there is, the component is also obtained by full addition of four signals.
Remains uncancelled. That is, this embodiment is mainly
This is to extract the Doppler shift of the second harmonic. However
However, the component with the Doppler shift of the fundamental frequency is extracted.
You. When the CW Doppler mode is performed,
As shown in FIG.₀Ream
A continuation wave is generated, and its phase is set to 0 °, 90
°, 180 °, and 270 °. At this time, the phase
Want to detect 1/2 of the reciprocal of switching cycle (equivalent to PRF)
Avoid aliasing by making it sufficiently larger than the Doppler shift
There is a need to. FIG. 20 shows the CW mode for the second harmonic component.
This shows another form of the transmission signal when implementing the plastic mode.
You. The transmission signal shown in FIG.₀+ Δf and f₀−
This is a combination of two signals Δf. When this signal is applied to the nonlinear echo source,
The frequency f₀+ Δf and f₀-Δf Miki
Sing is performed and frequency 2f_oIs obtained. this
The state is shown by a spectrum in FIG. As shown in FIG.
According to the transmission signal, the fundamental frequency f₀Will not be included
And without the need for any means to remove it,
Can perform CW Doppler measurement on harmonic components
You. In this case, Δf / 2 is also the Doppler shift to be detected.
Need to be large enough to prevent aliasing.
is there. FIG. 22 shows another embodiment of the transmitting / receiving section 2.
An example block diagram is shown for one channel. FIG.
In FIG. 10, the same parts as those in FIG.
Description is omitted. In FIG. 22, the A / D converter 207
The fundamental wave remover 211 is inserted between the
This allows the fundamental frequency f₀Success
Minutes are removed. The fundamental wave eliminator 211 is provided as shown in FIG.
Has a delay time corresponding to a half wavelength (λ / 2) of the fundamental wave.
Signal that passes through the delay circuit 212 and the signal that does not pass through it
The adder 213 adds the sum of
You. The delay circuit 212 is implemented by a shift register, for example.
Is achieved. The fundamental wave is generated by passing through the delay circuit 212.
The phase changes by 180 °, but the second harmonic component is 360 °.
° changes. Therefore, these are
Signal and the fundamental component cancel each other out.
And the second harmonic component is doubled. That is, the second high
Harmonic extraction is performed. Note that an analog delay circuit is
By using an analog adder for the adder 213
An analog fundamental wave remover can be configured. So
, The fundamental wave remover is provided before the A / D converter 207.
Can be The fundamental wave remover 211 includes a controller 209
It may be realized by the function of. That is,
The received signal stored in the memory 208 is
Signal of the same sound ray by the
What is necessary is just to shift and add. This gives the fundamental component
And the second harmonic component can be extracted. This
In this way, the hardware of the fundamental wave remover 211 is
This is convenient because it can be omitted. FIG. 24 shows another embodiment of the transmission / reception unit 2.
An example block diagram is shown for two adjacent channels.
A similar channel pair is used for all transducers of the ultrasonic probe 1.
Is provided. In FIG. 24, the same as FIG.
The same symbols are given to the parts and the description is omitted. [0113] Here, these two channels are transmitted and transmitted.
And a pair of channels involved in the formation of the receiving ultrasonic beam
It is. In both channels, the transmission signal generator 20
1 (201 ') to the transmission / reception switch 204 (20
4 ') and the controller 209 are driven in the present invention.
It is an example of an embodiment of the means. Controller 2
09 is an example of an embodiment of the adding means in the present invention.
You. The controller 209 includes the transmission signal generator 20
1 and 201 'to control the transmission signals they generate.
To give a phase difference equivalent to 90 ° of the fundamental wave
Has become. Thereby, the vibrators 100 and 10
0 'transmits ultrasonic waves having such a phase difference.
Waved. Note that a beamformer (not shown)
The ultrasonic waves transmitted from the transducers 100 and 100 'are the same.
Beamforming to have one sound ray or focus
Is managed. However, the above 9
The phase difference of 0 ° is not impaired. Give a phase difference corresponding to 90 ° of the fundamental wave
The method is to generate transmission signal generators 201 and 201 '
Transmission signal waveforms having a phase difference of 90 ° from each other
And a phase difference of 90 ° for the same waveform.
There is a way to give the appropriate time difference. The latter is easy to realize
It is preferred in that respect. Alternatively, the oscillators 100 and 100 '
The position of the ultrasonic radiation surface is set to 90 ° of the fundamental wave,
The ultrasonic wave travels a distance equivalent to a quarter wavelength (λ / 4)
You may make it differ in a line direction. In this case, send
Phase of transmission signal generated by signal generator 201, 201 '
It is preferable not to change. The phase difference corresponding to 90 ° of the fundamental wave is the second height.
There is a 180 ° phase difference for harmonics. For this reason,
The second ultrasonic wave transmitted from the moving elements 100 and 100 '
Even if harmonic components are included in the transmitted beam
Cancel each other out. Therefore, the
The co-source is a super harmonic consisting of only the fundamental wave (and the third harmonic)
Sound waves are emitted. Use filters in this way
Removing the second harmonic component from transmitted ultrasonic waves without transmission
Can be. The transducers 100 and 100 'receive
The wave echo signal is received and processed by each receiving system.
Stored in memories 208 and 208 '. In addition, receive
The beamformer (not shown)
Beam forming or beam steering or forming
Cushing and the like are performed. For the echo reception signal, the memory 208
And 208 'respectively.
The phase corresponding to 180 ° of the fundamental wave by the roller 209
They add up by the difference. As a result, the fundamental wave component of the received signal is
And disappear, while the second harmonic component is
The phase difference equivalent to 180 ° of the fundamental wave is 360 °
Since they have the same phase, they are doubled by addition. That is,
A received signal consisting of only two harmonics can be obtained. This
, And without using a filter,
Echo can be extracted. Note that the oscillators 100 and 100 'are basically
When the ultrasonic emission surface is shifted by λ / 4 of the wave
Is already the 90 ° phase of the fundamental between the two received signals
Because there is a difference, add a phase difference of 90 ° and add
It is possible to extract the echo of the second harmonic
You. (5) Three-dimensional imaging and tracking of tissue displacement FIG. 25 shows a state in which the ultrasonic probe 1 scans the inside of the subject.
Indicates a child. A transducer element as the ultrasonic probe 1
Having a two-dimensional array is used. Transceiver 2
Describes the beam forming of such an ultrasonic probe 1
Under the control, the inside of the subject is three-dimensionally scanned. The three-dimensional scanning inside the subject is performed at least in the first
At least once, a sound that is dense enough to obtain the desired spatial resolution
And B-mode processing based on the received signal.
A B-mode image is formed by the
Image data is stored in the storage unit 10 by the data processing unit 9.
You. Thus, the storage unit 10 has a desired spatial resolution of 3
A two-dimensional image (still image) is held. The attention point of this three-dimensional image is not determined.
Is done. As a point of interest, for example, as shown in FIG.
Corners, high-luminance parts, interfaces in the direction of distance perpendicular to the sound ray, sound rays
An interface in an azimuthal direction parallel to the above is selected. These highlights
It is enough to have a few or more than ten points. The point of interest is determined manually or automatically.
You. In the case of manual operation, the operator displays on the image displayed on the display unit 7.
Specify with. In the case of automatic, the image is
Edge detection is performed from the data by second derivative, etc.
Interface that is orthogonal to the sound ray by Hough transformation from inside
Are extracted, and the differential values of those interfaces, for example, are
The point of interest is determined at the point where it becomes large. The data processing section 9 controls the transmitting / receiving section 2.
This means that subsequent scans will be performed only on these points of interest.
And let them do it. Such scanning is performed by dozens of sound rays.
Scanning can be performed in real time. A three-dimensional image is formed based on the received signal,
It is stored in the storage unit 10. This 3D image is the current point of interest
It indicates the position. By the way, the tissue in the subject
Displacement and deformation occur or disappear within a short time
And the order of the arrays is not interchanged. I
Therefore, the amount of deformation of the three-dimensional image is estimated from the displacement of the point of interest.
Deform the first three-dimensional image obtained to match it
Is a relatively good approximation of the current state in the subject
A three-dimensional image can be obtained. FIG. 27 is a diagram for explaining an image deformation. What
Note that, for convenience of description, the expression is reduced to two dimensions. Picture
The deformation of the image is performed as follows. First scan to obtain original image with normal sound ray density
(FIG. 27A). Find the position of the point of interest by the next coarse scan,
Compare the new position of the point with the original position (FIG. 27)
(B)). A vector indicating the displacement from the original position of the point of interest is
(FIG. 27 (c)). Extrapolate the obtained vector to all pixels of the image
Then, a displacement vector is obtained (FIG. 27D). Transform original image based on displacement vector of all pixels
Then, the current image is set (FIG. 27E). Scanning of the point of interest, calculation of the displacement vector and
Deformation of the original image is better than three-dimensional scanning with regular sound ray density
Can be performed in a much shorter time. Therefore, above
By transforming the original image like
A three-dimensional image of resolution can be obtained in real time. Hereinafter, scanning only for the point of interest and the point of interest
Real time by repeating the deformation of the original image according to the displacement of
A three-dimensional image can be obtained. And this image
Real-time 3D image display by displaying on the display unit 7
Can be performed. Note that the deformation of the original image is
Address conversion table using the address conversion table.
By rewriting the table according to the displacement vector
This is preferable in terms of speeding up. The original image should be retaken at regular intervals.
Is preferable to obtain a three-dimensional image more faithful to the actual situation.
New Also, instead of always performing image deformation on the original image,
Alternatively, it may be performed on the previous image that has already been deformed.
No. The displacement of the point of interest is always tracked as described above.
Is displaced due to body movement, etc.
Can track its location based on the displacement of the point of interest.
Wear. Therefore, the structure at the current position of the part is always
It is possible to measure the concentration value of the shadow agent and the like. by this
For the first time, accurate measurement can be performed.
A measurement curve of the contrast agent can be obtained. [0134] As described in detail above, the problem is solved.
According to the first aspect of the present invention, two types of ultrasonic waves are transmitted.
Two types of eco-friendly products
-Since the difference between the received signals is determined, the nonlinear echo
Extract the echo from the source without using a filter etc.
An ultrasonic imaging method capable of performing the above can be realized. Further, according to a second invention for solving the problem,
According to the method, ultrasonic waves are transmitted in a plurality of phases, and
To obtain the sum of multiple received echo signals
Filter from the nonlinear echo source, etc.
Ultrasound imaging method that can extract without using
Can appear. Further, a third invention for solving the problem is provided.
According to the report, the two frequencies of the transmitted ultrasonic wave are transmitted to the nonlinear echo source.
Mixing, the frequency is twice the fundamental frequency.
Ultrasound imaging method that can obtain many echo signals
Can appear. Further, the fourth invention for solving the problem is described as follows.
According to the addition of the half-wave shift of the fundamental wave,
A component that can eliminate components and extract second harmonic components
A sound wave imaging method can be realized. [0138] In the fifth invention for solving the problem,
According to one pair of transducers involved in the formation of an ultrasonic beam,
And driven by a pair of transmission signals and
The pair of received signals of
The second harmonic component is not contained in the
Realizes an ultrasonic imaging method that includes only the second harmonic component
can do. [0139] Further, in the sixth invention for solving the problem,
According to this, you can track the region of interest based on the displacement of the point of interest.
For areas of interest whose features are not clear.
Displacement can be tracked and accurate measurement using contrast agent
An ultrasonic imaging method capable of performing the above can be realized. Further, according to a seventh invention for solving the problem,
According to the report, ultrasonic waves are transmitted at two different intensities,
Find the difference between the two types of received echo signals obtained
The echo from the nonlinear echo source.
Ultrasonic imaging device that can extract without using data
Can be realized. An eighth aspect of the present invention for solving the problem is as follows.
According to the method, ultrasonic waves are transmitted in a plurality of phases, and
To obtain the sum of multiple received echo signals
Filter from the nonlinear echo source, etc.
Ultrasound imaging device that can extract without using
Can appear. A ninth aspect of the present invention for solving the problems is as follows.
According to the report, the two frequencies of the transmitted ultrasonic wave are transmitted to the nonlinear echo source.
Mixing, the frequency is twice the fundamental frequency.
An ultrasonic imaging device capable of obtaining a number of echo signals
Can appear. The tenth invention for solving the problem
According to the addition of the half-wave shift of the fundamental wave,
A wave component can be eliminated and a second harmonic component can be extracted.
An ultrasonic imaging device can be realized. Further, an eleventh invention for solving the problem is provided.
According to, a pair of transducers involved in the formation of the ultrasonic beam
About the vibrations driven by a pair of transmission signals
Since the pair of received signals of the slaves are added,
The beam contains no second harmonic components and
Implements an ultrasonic imaging device containing only the second harmonic component.
Can be manifested. A twelfth invention for solving the problems
According to the tracking of the region of interest based on the displacement of the point of interest
In the region of interest whose characteristics are not clear.
Can be tracked and accurate measurements using contrast agents can be performed.
Thus, an ultrasonic imaging apparatus that can be realized can be realized. A thirteenth aspect for solving the problem is described below.
According to Ming, having a first oscillator and a second oscillator
Gives f₀And 2f_oProbe with two different frequencies
A tentacle can be realized. A fourteenth invention for solving the problems
According to this, the particle size distribution of the microballoons was set to 1: 2.
As a result, nonlinear echo is generated efficiently for the excitation ultrasonic wave
It is possible to realize an ultrasonic contrast agent that performs

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a configuration of an ultrasonic probe according to an example of an embodiment of the present invention; FIG. 3 is a diagram illustrating a configuration of an ultrasonic probe according to an example of an embodiment of the present invention; FIG. 4 is a diagram illustrating a frequency characteristic of the ultrasonic probe according to the example of the embodiment of the present invention; FIG. 5 is a diagram showing a configuration of an ultrasonic probe according to an example of an embodiment of the present invention. FIG. 6 is a diagram showing a configuration of an ultrasonic probe according to an example of an embodiment of the present invention. FIG. 7 is a diagram showing a configuration of an ultrasonic probe according to an example of an embodiment of the present invention. FIG. 8 is a diagram showing a configuration of an ultrasonic probe according to an example of an embodiment of the present invention. FIG. 9 is a diagram showing a configuration of an ultrasonic probe according to an example of an embodiment of the present invention. FIG. 10 is a block diagram of a transmission / reception unit in an apparatus according to an embodiment of the present invention. FIG. 11 is a block diagram of a transmission / reception unit in the device according to an example of the embodiment of the present invention. FIG. 12 is an explanatory diagram of an operation of a transmission / reception unit in the device according to the example of the embodiment of the present invention; FIG. 13 is an explanatory diagram of the operation of the transmission / reception unit in the apparatus according to an example of the embodiment of the present invention. FIG. 14 is an explanatory diagram of the operation of the transmission / reception unit in the apparatus according to the example of the embodiment of the present invention; FIG. 15 is an explanatory diagram of the operation of the transmission / reception unit in the apparatus according to the example of the embodiment of the present invention; FIG. 16 is an explanatory diagram of the operation of the transmission / reception unit in the apparatus according to an example of the embodiment of the present invention. FIG. 17 is an explanatory diagram of the operation of the transmission / reception unit in the apparatus according to an example of the embodiment of the present invention; FIG. 18 is an explanatory diagram of the operation of the transmission / reception unit in the device according to an example of the embodiment of the present invention. FIG. 19 is an explanatory diagram of the operation of the transmission / reception unit in the apparatus according to an example of the embodiment of the present invention. FIG. 20 is an explanatory diagram of the operation of the transmission / reception unit in the device according to the example of the embodiment of the present invention; FIG. 21 is an explanatory diagram of the operation of the transmission / reception unit in the apparatus according to an example of the embodiment of the present invention; FIG. 22 is a block diagram of a transmission / reception unit in the device according to an example of the embodiment of the present invention. FIG. 23 is a block diagram of a fundamental wave removing unit in the device according to an embodiment of the present invention; FIG. 24 is a block diagram of a transmission / reception unit in the device according to an example of the embodiment of the present invention; FIG. 25 illustrates an example of an apparatus according to an embodiment of the present invention.
It is a conceptual diagram of dimension scanning. FIG. 26 is a conceptual diagram of a point of interest in the device according to an example of the embodiment of the present invention. FIG. 27 is a conceptual diagram of image processing in an apparatus according to an embodiment of the present invention. FIG. 28 is a graph showing a time change of a measured value in a measurement using a contrast agent. [Description of Signs] 1 Ultrasonic probe 2 Transmission / reception unit 3 B-mode processing unit 4 Doppler processing unit 5 Color Doppler processing unit 6 Digital scan converter unit 7 Display unit 8 Recording unit 9 Data processing unit 10 Storage unit 11 Operation unit 101 , 103 Transducer array 102, 104 Backing material 100 Transducer 201 Transmission signal generator 202 Transmitter 203, 206 Filter 204 Transmission / reception switch 205 Receiver 207 A / D converter 208 Memory 209 Controller 210 Demodulator 211 Fundamental wave remover 212 delay circuit 213 adder

Claims (1)

(1) An ultrasonic imaging apparatus that transmits an ultrasonic wave to a subject and uses a second harmonic component of an echo of the ultrasonic wave. Transmitting means for alternately transmitting an ultrasonic wave having a second intensity substantially 1 / k times the first intensity; and an echo based on the ultrasonic wave transmitted at the first intensity; Receiving means for receiving an echo based on the ultrasonic wave transmitted at the second intensity; a signal substantially k times an echo received signal based on the ultrasonic wave transmitted at the second intensity; An ultrasonic imaging apparatus comprising: an arithmetic unit that obtains a difference signal from an echo reception signal based on an ultrasonic wave transmitted at an intensity.