JP2002301072A - Ultrasonic imaging method and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic imaging method capable of providing an image with a high SN ratio by improving the separation between a signal component and a noise component contained in the ultrasonic echo. SOLUTION: Plural kinds of ultrasonic waves having a plurality of transmission power and first frequencies are transmitted to an examee, and the ultrasonic waves reflected from the subject are detected to obtain plural kinds of detection signals. The detection signals are subjected to a band pass processing for passing a component having a second frequency, and an operation is performed by use of plural kinds of image data obtained on the basis of the processed detection signals, whereby new image data are calculated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic diagnostic system which constructs a diagnostic image based on image data obtained by transmitting an ultrasonic wave to a subject and receiving an ultrasonic echo reflected by the subject. The present invention relates to an ultrasonic imaging method and an ultrasonic imaging apparatus.

[0002]

2. Description of the Related Art Ultrasonic waves are reflected at places where the acoustic characteristic impedance changes, that is, at the interface between different media. An ultrasonic image is an image in which internal information of a subject such as a living body obtained using such properties of ultrasonic waves is formed as an image. That is, by transmitting an ultrasonic wave to an object such as a living body from an ultrasonic probe including a plurality of ultrasonic transducers and receiving an ultrasonic echo reflected back by a reflector existing inside the object, Obtain the internal information of the subject. By repeatedly collecting such internal information while changing the transmission direction of the ultrasonic wave, it is possible to configure, for example, the shape and movement of an organ in a living body as an image. Therefore, such an ultrasonic diagnosis is an effective diagnostic method for a disease in which a lesion can be recognized by the shape or movement of an organ.

On the other hand, when observing the flow of blood flow in the heart, a contrast agent is often used. The contrast agent used in ultrasonic imaging contains microbubbles that do not affect the human body, and is previously injected into the blood or body cavity of the subject. When such a microbubble contrast agent is irradiated with an ultrasonic wave, it generates a strong reflected wave including a second harmonic component having a frequency twice the fundamental frequency of the transmitted ultrasonic wave. Normally, in ultrasonic imaging using a contrast agent, a diagnostic image is formed by detecting such a second harmonic component.

[0004] In addition to the second harmonic component, the ultrasonic wave received by the ultrasonic imaging apparatus is m / n times the frequency of the transmitted ultrasonic wave (m and n are natural numbers and m / n n is not an integer) or a subharmonic component with a frequency of
This includes acoustic radiation induced by the transmitted ultrasonic waves, noise that the ultrasonic waves randomly reflected in the body cavity, and the like. The sub-harmonic component is generated by the chaotic vibration and the bifurcation of the microbubbles.

However, regardless of whether a fundamental component of an ultrasonic echo is detected or a harmonic component or a subharmonic component is detected, transmission is performed with a constant transmission power in conventional ultrasonic imaging. Therefore, it is difficult to distinguish between a signal component and a noise component included in the ultrasonic echo, and it has been difficult to separate a useful signal and a noise.

Incidentally, Japanese Patent Application Publication No. Hei 11-1
No. 37547 discloses that a plurality of signals included in echoes from a microbubble contrast agent are comprehensively used by using echoes in a fundamental frequency band of a transmission ultrasonic wave and a frequency band outside the same in image generation, respectively. There is disclosed an ultrasonic imaging method capable of performing imaging by using an ultrasonic imaging method. According to this method, various display images can be obtained by using various signals such as a second harmonic and a subharmonic included in the echo. However, this method
It does not exclude noise or the like included in the echo.

[0007]

SUMMARY OF THE INVENTION In view of the above, the present invention improves the separation between a signal component and a noise component contained in an ultrasonic echo and obtains an image having a high SN ratio. It is an object to provide a sound wave imaging method and an ultrasonic wave imaging device.

[0008]

In order to solve the above problems, an ultrasonic imaging method according to the present invention transmits a plurality of types of ultrasonic waves having a plurality of transmission powers and a first frequency to a subject, Step (a) of detecting ultrasonic waves reflected from the subject to obtain a plurality of types of detection signals, and step (a).
(B) performing a band-pass process for passing the component having the second frequency on the plurality of types of detection signals obtained in the step (b), and performing a plurality of types based on the plurality of types of the detection signals processed in the step (b). (C) obtaining the image data of step (c), and step (d) of calculating new image data by performing an operation using the plurality of types of image data obtained in step (c).

Further, in the ultrasonic imaging apparatus according to the present invention, a plurality of ultrasonic transducers are arranged to transmit ultrasonic waves having a predetermined transmission power and a first frequency to the subject, and to reflect the ultrasonic waves from the subject. Transmitting / receiving means for receiving an ultrasonic wave and outputting a detection signal, and performing band pass processing for passing a component having a second frequency to the detection signal output from the ultrasonic transmitting / receiving means to obtain image data Signal processing means, control means for controlling the ultrasonic transmission / reception means so as to change the transmission power of the transmitted ultrasonic waves, and a plurality of types obtained by transmitting / receiving the ultrasonic waves while changing the transmission power of the transmitted ultrasonic waves Storage means for storing image data of a plurality of types, and an operation for calculating new image data by performing an operation using a plurality of types of image data stored in the storage means ; And a stage.

According to the present invention, a plurality of types of frame data are obtained based on ultrasonic echoes obtained by transmitting and receiving a plurality of types of ultrasonic waves having different transmission powers, and arithmetic processing is performed on these frame data. In this case, the image data is calculated to obtain an ultrasonic image having a high SN ratio.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. The same components are denoted by the same reference numerals, and description thereof will be omitted. FIG. 1 is a block diagram showing an ultrasonic imaging apparatus according to one embodiment of the present invention. This ultrasonic imaging apparatus has an ultrasonic probe 20 including an ultrasonic transducer array in which a plurality of ultrasonic transducers are arranged. PZT (lead zirconate titanate) as the ultrasonic transducer
And a vibrator such as PVDF (polymer piezoelectric element). Electrodes are attached to these vibrators and connected to electronic circuits included in the ultrasonic imaging apparatus main body via lead wires. Further, the ultrasonic probe 20 includes a backing material that supports the vibrator and acoustically damps the vibrator, an acoustic matching layer for efficiently transmitting ultrasonic waves, and an acoustic wave for focusing ultrasonic waves. A lens or the like may be included.

The ultrasonic imaging apparatus also includes an ultrasonic transmission / reception unit 30 for controlling transmission / reception of ultrasonic waves by the ultrasonic probe 20, and processing of received ultrasonic waves for processing sound ray data (A-mode data). A waveform processing unit 40 that generates
An image forming unit 50 that stores frame data constituted by accumulating sound ray data, performs arithmetic processing on the stored frame data, and forms image data, and an image forming unit 50. It has a display section 60 for displaying an image based on image data, a system control section 70 for controlling these sections, and an input section 71 for inputting various commands and the like.

FIG. 2 shows the configuration of the ultrasonic transmission / reception unit 30. The ultrasonic transmission / reception unit 30 controls a transmission / reception condition of an ultrasonic wave under the control of the system control unit 70, a transmission power control circuit 302, a transmission frequency control circuit 303, and a reception sensitivity control circuit 304. And a reception delay control circuit 305.

The transmission power control circuit 302 controls amplitudes output from the plurality of transmission driving circuits 307 in order to transmit ultrasonic waves having a predetermined transmission power under the control of the system control unit 70. The transmission frequency control circuit 303 controls the signal generator 306 in order to transmit an ultrasonic wave having a predetermined frequency under the control of the system control unit 70. The signal generator 306 generates a signal having a predetermined frequency under the control of the transmission frequency control circuit 303. The transmission drive circuit 307 outputs a drive signal by amplifying and delaying the signal generated by the signal generator 306.

The transmission delay control circuit 301 controls the delay time of drive signals output from the plurality of transmission drive circuits 307. The transmission / reception switching circuit 311 includes the ultrasonic probe 20.
Are connected, and the plurality of drive signals output from the signal generator 306 are input to the ultrasonic transducer array included in the ultrasonic probe 20 via the transmission / reception switching circuit 311. Transmit aperture in the array (apert)
ure), the plurality of ultrasonic transducers
A plurality of ultrasonic waves having a phase difference corresponding to the time difference between these drive signals are transmitted toward the subject. An ultrasonic beam is formed by the wavefront synthesis of the plurality of ultrasonic waves, and the ultrasonic beam can be scanned by controlling the delay time in the transmission drive circuit 307.

The ultrasonic probe 20 transmits an ultrasonic beam to a subject, and a reflected wave (echo) reflected from the subject.
And outputs a detection signal. These detection signals are
The signal is input to the plurality of amplifiers 308 via the transmission / reception switching circuit 311 and amplified. At this time, the reception sensitivity control circuit 30
4 controls the gain of the plurality of amplifiers 308, thereby controlling the receiving sensitivity. The reception delay control circuit 3
05 controls the delay time of the detection signal in the reception delay circuit 309. That is, the reception delay circuit 309 adjusts the phase by giving a time difference to the plurality of detection signals. Further, the adding unit 310 adds the plurality of phase-adjusted detection signals to form a detection signal along a sound ray. As described above, by controlling the delay time in the reception delay circuit 309, it is possible to scan a received sound ray in accordance with an ultrasonic beam to be transmitted.

As a scanning method of an ultrasonic beam (sound ray), for example, as shown in FIG. 3, a sound ray 202 transmitted from a radiation point 200 in the Z direction is scanned in a two-dimensional area 206 in a fan shape in the θ direction. Sector scan can be performed. In addition, by sequentially moving the transmission apertures formed by the ultrasonic transducers arranged in the ultrasonic probe 20 along the arrangement direction, the sound transmitted from the radiation point 200 in the Z direction as shown in FIG. Line 202
Can be moved in parallel, so that a linear scan for scanning the sound ray 202 in the x direction in the two-dimensional area 206 can be performed. Further, when the ultrasonic transducer array included in the ultrasonic probe 20 is a convex array, as shown in FIG. 5, the radiation point 200 is scanned along an arc-shaped trajectory by scanning a sound ray similarly to the linear scan. To move the sound ray 202 to the two-dimensional area 2
At 06, a convex scan for scanning in the θ direction in a fan shape may be performed.

In order to transmit and receive such ultrasonic waves,
The transmission / reception switching circuit 311 switches between transmission of a drive signal to the ultrasonic probe and reception of a detection signal from the ultrasonic probe. Referring to FIG. 1 again, the ultrasonic transmitting and receiving unit 30
The detection signal formed in step (1) is output to the waveform processing unit 4 for each sound ray.
Input to 0. The waveform processing unit 40 includes a fundamental wave processing unit 41
And a sub-harmonic processing unit 42, extracts a component having a predetermined frequency from the input detection signal, and generates A-mode data based on the extracted signal.

Here, the subharmonic is a component having a frequency of m / n times the transmitted ultrasonic wave (m, n).
n is a natural number and m / n is not an integer), which is generated by chaotic vibration and bifurcation of microbubbles. The echo by the microbubble contrast agent contains a subharmonic component in addition to a fundamental component and a harmonic component.

Referring to FIG. 6, the fundamental wave processing unit 41
A bandpass filter 411, a logarithmic conversion circuit 412,
It has a detection circuit 413 and an A / D converter 414. The bandpass filter 411 performs a bandpass process on the input detection signal. Bandpass filter 4
Numeral 11 is set to a frequency so as to pass a component of a fundamental wave included in the detection signal. The logarithmic conversion circuit 4
Reference numeral 12 performs logarithmic conversion on the fundamental wave component passed through the bandpass filter 411. Further, the detection circuit 413
Performs envelope detection on the logarithmically converted signal and generates an A-scope signal whose amplitude represents the echo intensity at each reflection point on the sound ray. The A / D converter 414 converts the generated A-scope signal into a digital signal, and generates A-mode data in which the amplitude at each reflection point on the sound ray is a luminance value.

The sub-harmonic processing section 42 has a band-pass filter 421, a logarithmic conversion circuit 422, a detection circuit 423, and an A / D converter 424. The band pass filter 421 performs band pass processing on the input detection signal. The frequency of the bandpass filter 421 is set so as to pass the subharmonic component included in the detection signal. The logarithmic conversion circuit 42
2 performs logarithmic conversion on the fundamental wave component passed through the bandpass filter 421. Further, the detection circuit 423
Envelope detection is performed on the logarithmically converted signal to generate an A-scope signal whose amplitude indicates the echo intensity at each reflection point on the sound ray. The A / D converter 424 converts the generated A-scope signal into a digital signal, and generates A-mode data having a luminance value at each reflection point on the sound ray.

[0022] The waveform processing unit 40 performs the A based on a harmonic component having a frequency that is an integral multiple of the transmitted ultrasonic wave in addition to the fundamental component and the subharmonic component included in the detection signal.
Mode data may be generated. For this purpose, the frequency component passed by the band-pass filter in the fundamental wave processing unit 41 or the subharmonic processing unit 42 may be changed to a harmonic component. Alternatively, a harmonic processing unit including a band-pass filter that passes a harmonic component may be separately provided.

The image forming section 50 has a primary storage section 51, an address control section 52, an image processing section 53, a digital scan converter (DSC) 54, and a secondary storage section 55. The primary storage unit 51 stores the A-mode data output from the fundamental processing unit 41 and the sub-harmonic processing unit 42 in predetermined areas. A-mode data sequentially input to the primary storage unit is accumulated to form a plurality of types of frame data. The address control unit 52 includes:
The storage area in the primary storage unit 51 is controlled according to the control of the system control unit 70.

The image processing section 53 performs image processing such as arithmetic processing on the frame data stored in the primary storage section 51. That is, the image processing unit 53 performs arithmetic processing such as superposition averaging and integration of data at corresponding points between a plurality of types of frame data obtained by transmitting and receiving ultrasonic waves having different transmission powers, Mode image data is calculated. Further, the image processing unit 53 performs image processing such as interpolation, response modulation processing, and gradation processing on the calculated B-mode image data.

The DSC 54 scan-converts the image-processed B-mode image data to create image data for display. The display image data created by the DSC 54 is stored in the secondary storage unit 55. The display unit 60 displays an ultrasonic image based on the display image data stored in the secondary storage unit 55. It is desirable that the display unit 60 be capable of color display.

The system control unit 70 transmits a plurality of types of ultrasonic waves having different transmission powers, and performs arithmetic processing on a plurality of types of frame data obtained based on a fundamental wave component and a sub-harmonic component included in the ultrasonic echo. Thus, each unit is controlled to acquire an ultrasonic image. Various information and commands are input from the input unit 71. Input unit 71
Is composed of, for example, a keyboard, an operation panel having operation tools, a pointing device, and the like.

Next, the operation of the ultrasonic imaging apparatus according to the present embodiment will be described with reference to FIGS. 1, 2, 6, and 7. FIG. 7 is a flowchart illustrating the operation of the ultrasonic imaging apparatus according to the present embodiment. In the present embodiment, a microbubble contrast agent is injected into a subject to be imaged in advance. First, in step S1, initialization is performed. That is, in order to transmit a plurality of types of ultrasonic waves having different transmission powers, the value of the transmission power e (n) is set (n = 1, 2,...). Here, the value of the frequency f of the ultrasonic wave to be transmitted is also set. After the initialization, the system control unit 70 first outputs a control signal to the transmission power control circuit 302 and the transmission frequency control circuit 303 in order to transmit an ultrasonic wave having the transmission power e (n).

Next, in step S2, an ultrasonic wave having a transmission power e (n) and a frequency f is transmitted from the ultrasonic probe 20 to the subject. Signal generator 30
6 generates a signal for transmitting an ultrasonic wave having a frequency f, and supplies the signal to the transmission drive circuit 307. The transmission drive circuit 307 gives a predetermined delay to the signal under the control of the transmission delay control circuit 301, and transmits the drive signal to the ultrasonic probe 20 at the transmission power e (n) controlled by the transmission power control circuit 302. . Thereby, the plurality of ultrasonic transducers included in the ultrasonic probe 20 respectively transmit ultrasonic waves having a phase difference corresponding to the time difference of the drive signal, and an ultrasonic beam, that is, an ultrasonic beam, A sound ray is formed and transmitted to the subject.

The transmitted ultrasonic beam is reflected by a reflector existing inside the subject. Here, when the ultrasonic beam irradiates the microbubble contrast agent present inside the subject, m / n of the fundamental frequency of the transmitted ultrasonic wave is obtained.
A subharmonic echo having twice the frequency is generated (m and n are natural numbers, and m / n is not an integer). In step S3, the plurality of ultrasonic transducers included in the ultrasonic probe 20 receive the transmitted ultrasonic echo including the fundamental wave component and the sub-harmonic component of the transmitted ultrasonic wave, convert the ultrasonic echo into an electric signal, and convert the electric signal into a detection signal. Output as

These detection signals are subjected to various signal processings in step S4. The detection signal is output from the amplifier 30
8, the signal is input to the reception delay circuit 309, is subjected to a predetermined delay, is phase-adjusted, and is added in the adder 310 to form a detection signal for each sound ray.

In step S5, the detection signal is subjected to waveform processing. In the waveform processing unit 40 shown in FIG. 6, the detection signal is divided into a fundamental wave processing unit 41 and a sub-harmonic processing unit 42.
Is input to both. Here, the bandpass filter 4 of the fundamental wave processing unit 41 is controlled by the system control unit 70.
11 is set to pass the component having the frequency f, and the bandpass filter 421 of the subharmonic processing unit 42 is set to pass the component having the frequency f / 2. The fundamental wave processing unit 41 generates A-mode data based on the fundamental wave component included in the input detection signal. Further, the sub-harmonic processing unit 42 generates A-mode data based on the sub-harmonic component included in the input detection signal.

The transmission and reception of the ultrasonic beam in steps S2 to S5 are repeated a plurality of times at predetermined time intervals while changing the transmission direction of the ultrasonic beam (step S5).
6). Here, the time interval for transmitting the ultrasonic beam is controlled by the timing of signal generation in the signal generator 306. Further, the transmission direction of the ultrasonic beam is changed by controlling the delay time given to the transmission drive circuit 307, and accordingly, the reception direction of the reflected wave also controls the delay time in the reception delay circuit 309. It will be changed by

The A-mode data generated in the fundamental wave processing unit 41 and the sub-harmonic processing unit 42 are output to the image forming unit 50 and stored in predetermined areas of the primary storage unit 51 in step S7. Where 1
The storage area of the next storage unit 51 is specified by the address control unit 52 controlled by the system control unit 70.

By performing the sound ray scanning in steps S2 to S6, A-mode data is accumulated in the primary storage unit 51 (step S7). A mode data for one frame constitutes frame data. When the frame data for a predetermined frame is acquired, in step S8, the system control unit 70 changes the transmission power of the ultrasonic beam to be transmitted to e (n + 1) (step S9), and again performs the sound in steps S2 to S5. Repeat line scanning.

The A-mode data generated by the sound ray scanning in steps S2 to S6 is stored in a predetermined area of the primary storage unit 51 in step S7. When the transmission of the ultrasonic waves of all the set transmission powers is completed, the process proceeds to the image processing in step S10. As described above, while changing the transmission power of the ultrasonic wave to be transmitted, step S
Steps 2 to S7 are repeated as necessary. Note that the transmission power may be changed every frame, but when the frame rate is high, it is preferable to change the transmission power every two to three frames.

Here, the reason why a plurality of types of ultrasonic waves having different transmission powers are used in ultrasonic imaging will be described. FIG.
, Curve A indicates the echo intensity with respect to the transmission power of the microbubble contrast agent injected into the blood. Further, a straight line B indicates the echo intensity with respect to the transmission power of noise generated due to various factors such as scattering or interference of the ultrasonic wave in the subject. As shown by the curve A, the acoustic characteristics of the microbubble contrast agent show that the echo intensity shows an almost linear response to the transmission power in a range where the transmission power is small, and the echo sharply increases when the transmission power exceeds a certain value. It has the feature of increasing strength. On the other hand, as shown by the straight line B, the noise intensity shows a linear response to the transmission power over a wide range. Therefore, the transmission power e ₁
Frame data and transmission power e created based on
By taking the difference between the corresponding data included in each of the frame data created on the basis of _2, SN
The ratio can be improved.

Referring again to FIG. 1 and FIG. 7, in step S10, the image processing section 53 performs arithmetic processing on a plurality of frame data stored in the primary storage section 51 to calculate B-mode image data. I do. First, the image processing unit 53 selects, based on different transmission powers e ₁ and e ₂ (e ₂ > e ₁ ), a plurality of types of frame data obtained based on sub-harmonic components for ultrasonic waves having different transmission powers. The two types of frame data obtained as described above are extracted.
At this time, one of the extracted frame data is the frame data having the maximum luminance among a plurality of types of frame data obtained based on the sub-harmonic components stored in the primary storage unit 51, and the other Is preferably the frame data having the minimum luminance among the plurality of types of frame data. Next, the image processing unit 53
Using the corresponding data D (e ₁ ) and D (e ₂ ) included in the extracted two types of frame data, respectively, D (e ₁ , e ₂ ) = D (e ₂ ) −D (e ₁ ) The difference image data is calculated based on the difference obtained by the above. Alternatively, the image processing unit 53 outputs the data D (e ₁ )
And D (e ₂ ) and the positive coefficients K ₁ and K _{2, the difference} is calculated based on D (e ₁ , e ₂ ) = K ₂ × D (e ₂ ) −K ₁ × D (e ₁ ). Image data may be calculated.

The image processing section 53 may perform luminance conversion on the difference image data that has been subjected to the arithmetic processing. For example,
As a constant used in the luminance conversion, the difference image data is subjected to the luminance conversion using an average value of the minimum luminance value and the maximum luminance value in the data included in the plural types of frame data stored in the primary storage unit. I do. The difference image data or the brightness-converted difference image data represents B-mode image data. Further, the image processing unit 53 performs image processing such as interpolation, response modulation processing, and gradation processing on the B-mode image data. The image processing unit 53 may perform the same arithmetic processing on a plurality of types of frame data created based on the fundamental wave component and the harmonic component and stored in the primary storage unit.

Next, in step S11, the DSC 5
Reference numeral 4 performs scan conversion on the B-mode image data on which the image processing has been performed to create image data for display. The display image data is stored in the secondary storage unit 55 in step S12.

In step S13, the display unit 60
An ultrasonic image is displayed based on the display image data stored in the secondary storage unit 55. Here, the ultrasound image created based on the fundamental wave component is an image representing a microbubble contrast agent, a nearby organ, and the like. An ultrasonic image created based on the subharmonic component is an image that strongly represents a microbubble contrast agent. Therefore, by displaying an ultrasonic image created based on the fundamental wave component and an ultrasonic image created based on the sub-harmonic component side by side, or by superimposing and displaying the two, the microbubbles inside the subject are displayed. The position and movement of the contrast agent can be clarified.

In the present embodiment, a sub-harmonic component having a frequency half of the fundamental frequency of the transmitted ultrasonic wave is used, but a sub-harmonic component having a frequency other than that may be used. . In that case, the frequency passed by the band-pass filter 421 of the sub-harmonic processing unit 42 may be set to, for example, f / 3. Further, in the present embodiment, the imaging of the B-mode image has been described. However, the dynamic image can be captured using the Doppler shift caused by the subharmonic echo.

[0042]

As described above, according to the present invention, in ultrasonic imaging, an image is formed based on ultrasonic echoes obtained by transmitting a plurality of types of ultrasonic waves having different transmission powers. It is possible to improve the separation between the signal component and the noise included in the ultrasonic echo and obtain an ultrasonic image with a high SN ratio.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an ultrasonic imaging apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of an ultrasonic transmission / reception unit of FIG. 1;

FIG. 3 is a diagram showing a scanning method (sector scan) of an ultrasonic beam.

FIG. 4 is a diagram showing a scanning method (linear scan) of an ultrasonic beam.

FIG. 5 is a diagram showing a scanning method (convex scan) of an ultrasonic beam.

FIG. 6 is a block diagram illustrating a configuration of a waveform processing unit in FIG. 1;

FIG. 7 is a flowchart illustrating an ultrasonic imaging method according to an embodiment of the present invention.

FIG. 8 is a diagram illustrating characteristics of echo intensity with respect to transmission power.

[Explanation of symbols]

 Reference Signs List 10 subject 20 ultrasonic probe 30 ultrasonic transmitting / receiving unit 40 waveform processing unit 41 fundamental wave processing unit 42 subharmonic processing unit 50 image forming unit 51 primary storage unit 52 address control unit 53 arithmetic unit 54 digital scan converter (DSC) 55 Secondary storage unit 56 Image processing unit 60 Display unit 70 System control unit 71 Input unit 101 Microbubble contrast agent 200 Radiation point 202 Sound ray 206 Two-dimensional area 301 Transmission delay control circuit 302 Transmission power control circuit 303 Transmission frequency control circuit 304 Reception Sensitivity control circuit 305 Reception delay control circuit 306 Signal generator 307 Transmission drive circuit 308 Amplifier 307 Reception delay circuit 309 Addition unit 310 Transmission / reception switching circuit 411, 421 Bandpass filter 412, 422 Logarithmic conversion circuit 413, 423 Detection circuit 4 4,424 A / D converter

Claims (14)

[Claims] A step of transmitting a plurality of types of ultrasonic waves having a plurality of transmission powers and a first frequency to a subject, detecting the ultrasound reflected from the subject, and obtaining a plurality of types of detection signals; ), A step (b) of performing band-pass processing for passing a component having the second frequency to the plurality of types of detection signals obtained in step (a), and a plurality of types of detection signals processed in step (b). Step (c) of obtaining a plurality of types of image data based on the detection signal
And (d) calculating new image data by performing an operation using a plurality of types of image data obtained in step (c). 2. The step (a) of obtaining a detection signal by scanning an ultrasonic wave having a predetermined transmission power and a first frequency is repeated a plurality of times while changing the transmission power of the ultrasonic wave to be transmitted. Step (c) includes obtaining a plurality of types of frame data based on the plurality of types of detection signals processed in step (b), and step (d). 2. calculating new frame data by performing an operation using a plurality of types of frame data obtained in step (c).
The ultrasonic imaging method according to the above. 3. The ultrasonic imaging method according to claim 2, wherein step (a) includes changing the transmission power of the ultrasonic wave to be transmitted at a cycle of 2 or 3 frames. 4. A step (b) includes a band-pass process for passing a component having a _second frequency f ₂ represented by f ₂ = mf ₁ (m is a natural number) for the first frequency f _1. The ultrasonic imaging method according to any one of claims 1 to 3, comprising performing. 5. The method as claimed in claim 5, wherein the step (b) is performed by injecting the injection
Sub-harmonic reflected by the trapped microbubble contrast agent
Nick echo component, the first frequency f ₁Against
f_Two= (M / n) f₁(M and n are natural numbers, where m / n
Is not an integer)._TwoHaving
Billing, including performing bandpass processing to pass through minutes
Item 4. The ultrasonic imaging method according to any one of Items 1 to 3. 6. The method according to claim 1, wherein the step (d) comprises transmitting powers e ₁ and e _2.
Calculating new image data using the two types of image data D (e ₁ ) and D (e ₂ ) obtained by transmitting and receiving the ultrasonic wave, and the image data D (e ₁ ,
The _{e 2), D (e 1} , e 2) = D (e 2) -D ( including the step of calculating as e _1), ultrasonic imaging method according to any one of claims 1-5. 7. Step (d) includes transmitting powers e ₁ and e _2.
Calculating new image data using the two types of image data D (e ₁ ) and D (e ₂ ) obtained by transmitting and receiving the ultrasonic wave, and the image data D (e ₁ ,
The e _2), using a positive coefficient K _1, K _2, comprising the step of calculating the _{D (e 1, e 2)} = K 2 × D (e 2) -K 1 × D (e 1), An ultrasonic imaging method according to claim 1. 8. An ultrasonic transducer having a plurality of ultrasonic transducers arranged therein, transmitting ultrasonic waves having a predetermined transmission power and a first frequency to a subject, receiving ultrasonic waves reflected from the subject, and generating a detection signal. An ultrasonic transmitting / receiving unit for outputting, and a second detection signal output from the ultrasonic transmitting / receiving unit,
Signal processing means for obtaining image data by performing band-pass processing for passing a component having the following frequency: control means for controlling the ultrasonic transmission / reception means so as to change transmission power; and ultrasonic waves while changing transmission power. A storage unit that stores a plurality of types of image data obtained by transmitting and receiving, and an operation unit that calculates new image data by performing an operation using the plurality of types of image data stored in the storage unit, An ultrasonic imaging apparatus comprising: 9. The storage unit stores a plurality of types of frame data obtained by scanning an ultrasonic wave while changing transmission power, and the arithmetic unit stores a plurality of types of frame data stored in the storage unit. 9. The ultrasonic imaging apparatus according to claim 8, wherein new frame data is calculated by performing an operation using the frame data. 10. The ultrasonic transmission apparatus according to claim 8, wherein said control means controls said ultrasonic transmission / reception means so as to change the transmission power of the ultrasonic wave to be transmitted at a cycle of 2 or 3 frames. Sound wave imaging device. 11. The signal processing means according to claim 1, wherein
₁For f_Two= Mf ₁(M is a natural number)
Frequency f_TwoBand-pass processing to pass components having
11. The method according to claim 8, wherein the application is performed.
On-board ultrasonic imaging device. 12. The signal processing means according to claim 1, wherein the sub-harmonic echo component reflected by the microbubble contrast agent injected into the subject in advance is f ₂ = (m / n) for the first frequency f _1. ) F ₁ (m and n are natural numbers, where m
The ultrasonic imaging apparatus according to any one of claims 8 to 10, wherein bandpass processing is performed to pass a component having a _second frequency f2 represented by (/ n is not an integer). 13. The method according to claim 12, wherein the calculating means stores the information in the storage means.
Transmission power e ₁, E_TwoTransmitting and receiving ultrasonic waves
Two types of image data D (e₁), D (e_Two)
Is used to calculate the image data D (e₁, E_Two) With D (e₁, E_Two) = D (e_Two) -D (e₁The method according to any one of claims 8 to 12, wherein:
2. The ultrasonic imaging apparatus according to claim 1. 14. The computer according to claim 1, wherein said calculating means stores the data in said storing means.
Transmission power e ₁, E_TwoTransmitting and receiving ultrasonic waves
Two types of image data D (e₁), D (e_Two)
Is used to calculate the image data D (e₁, E_Two),
Positive coefficient K₁, K_TwoUsing D (e₁, E_Two) = K_Two× D (e_Two) -K₁× D (e₁The method according to any one of claims 8 to 12, wherein:
2. The ultrasonic imaging apparatus according to claim 1.