JP4427507B2 - Ultrasonic diagnostic equipment - Google Patents

Description

  The present invention relates to an ultrasonic diagnostic apparatus suitable for a contrast echo method in which an ultrasonic contrast agent is administered to a subject and a tomographic image is obtained using a received signal including a reflected ultrasonic signal from the contrast agent. The present invention relates to a technique for intelligent transmission / reception condition setting, reception signal processing, and physical quantity measurement based on reception signals.

  Medical applications of ultrasonic signals are one of the ultrasonic diagnostic apparatuses in various fields. An ultrasonic diagnostic apparatus is an apparatus that obtains an image signal by transmitting and receiving an ultrasonic signal, and is used in various modes by utilizing the noninvasive nature of the ultrasonic signal. The mainstream of this ultrasonic diagnostic apparatus is a type that obtains a tomographic image of a soft tissue of a living body using an ultrasonic pulse reflection method. This imaging method can obtain a tomographic image of a tissue non-invasively and can be displayed in real time compared to other medical modalities such as X-ray diagnostic equipment, X-ray CT scanner, MRI equipment, and nuclear medicine diagnostic equipment. The apparatus is small and relatively inexpensive, has no exposure to X-rays, and has many advantages such as blood flow imaging based on an ultrasonic Doppler method. For this reason, it is widely used in the diagnosis of the heart, abdomen, mammary gland, urology, and gynecology. In particular, by simply operating the ultrasound probe on the body surface, heart beats and fetal movements can be observed in real time, and since there is no exposure, the test can be repeated many times. It has various advantages that it can be easily inspected.

  In the field of this ultrasonic diagnostic apparatus, recently, when performing an examination of the heart, abdominal organs, etc., a contrast echo method that injects an ultrasonic contrast agent from a vein and evaluates blood flow dynamics has attracted attention. . The method of injecting a contrast medium from a vein is less invasive than the method of injecting from a artery, and diagnosis by this evaluation method is becoming widespread. The main components of the ultrasound contrast agent are microbubbles (microbubbles), which serve as a reflection source for reflecting ultrasound signals. The higher the injection amount and concentration of the contrast agent, the greater the contrast effect. However, due to the nature of the bubbles in the contrast agent, there are situations where the contrast effect time is shortened by ultrasonic irradiation. In view of such a situation, a persistent and pressure-resistant contrast medium has been developed in recent years, but there is a concern that the long-term stay of the contrast medium in the body leads to an increase in invasiveness.

  When this contrast echo method is performed, contrast agents are successively supplied to the region of interest of the subject site by blood flow. For this reason, even if an ultrasonic wave is irradiated and the bubble disappears once, it is assumed that the contrast effect is maintained if a new bubble flows into the region of interest at the time of the next ultrasonic irradiation. However, in practice, ultrasonic transmission / reception is usually performed thousands of times per second, and considering the fact that organs with slow blood flow velocity and blood flow dynamics of relatively thin blood vessels exist. On the diagnostic image, bubbles disappear one after another before confirming the luminance enhancement by the contrast agent, and the contrast effect is instantly attenuated.

  Among the diagnostic methods using a contrast agent, the most basic diagnostic method is to know the presence or absence of blood flow at a diagnostic site by examining the presence or absence of brightness enhancement by a contrast agent. In addition, advanced diagnostic methods include a method of knowing temporal changes in the spatial distribution of contrast medium from the extent of brightness change and brightness enhancement at the diagnosis site, and the time from the injection of contrast medium to the region of interest. , And a technique for obtaining a change in echo luminance over time (Time Intensity Curve: TIC) or a maximum luminance due to a contrast agent in the ROI.

  This contrast echo method can also be effectively carried out by a harmonic imaging method that forms an image using a non-fundamental wave component of an ultrasonic echo signal. The harmonic imaging method is an imaging method that separates and detects only the non-fundamental wave component due to the nonlinear behavior that occurs when the microbubbles that are the main components of the contrast agent are ultrasonically excited. Since non-linear behavior is unlikely to occur, a contrast agent image with a good contrast ratio can be obtained.

  Further, as described above, regarding the phenomenon in which microbubbles disappear due to the irradiation of ultrasonic waves, the present inventors have published one research presentation, “Preliminary Proceedings of the Japanese Society of Ultrasonic Medicine, p.275, 1996- 6 ”(see Non-Patent Document 1), and reported that luminance enhancement is improved by an imaging method called flash echo imaging (or Trangient Respose Imaging). In principle, this imaging method replaces the conventional continuous scan of several tens of frames per second with an intermittent transmission configuration of one frame per several seconds. This is a method of trying to obtain a high echo signal by eliminating dense microbubbles at once.

  On the other hand, there are currently two methods for administering a contrast agent into the body. One is a method called bolus injection, in which a contrast agent inhaled into a syringe is administered at a slow speed, although at a slow rate. The other is called continuous infusion method, which is administered by taking a small amount over a long period of time like infusion. The former bolus injection method is relatively easy to administer, and the contrast medium reaching the region of interest has high peak brightness and is suitable for TIC processing, but the staining time is short and not constant. There is also an aspect. When the latter continuous injection method is carried out, it is necessary to control the injection amount using a dedicated instrument such as a magnetic flux injector, but there is an advantage that the contrast agent concentration in the region of interest can be kept constant for a certain period of time. For this reason, it is possible to use a contrast agent having a contrast effect even if diluted to some extent.

From the above, the key points when the contrast agent is used for ultrasonic diagnosis are enhancement of the received signal from the blood flow and quantitative evaluation of the blood flow dynamics.
Proceedings of the Japan Society for Ultrasonic Medicine p. 275, 1996-6

  Nonetheless, the problems with the contrast echo method described above provide simple and more detailed information, mainly due to the physical properties of the contrast agent that the lifetime of bubbles is shortened by ultrasonic irradiation. There is a lack of quantification techniques. In particular, the former problem is not simple. In the contrast echo method, the S / N ratio is not improved by increasing the transmission output as in the prior art. The former problem suggests that there is an optimum value for the transmission output at a transmission level that is relatively lower than the transmission output used conventionally. Conventionally, the control method of the transmission output from this point of view is known. It was not done.

  The present invention introduces a new quantified measurement method in ultrasonic diagnostics using the contrast echo method, and provides more detailed blood flow information by enrichment and enhancement of the measurement method.

  Another object of the present invention is to optimize the transmission conditions of ultrasonic pulses so that a more effective contrast echo method can be performed, and to be quantified in ultrasonic diagnosis in which the contrast echo method is performed. Introducing new measurement methods and providing more detailed blood flow information by enriching and enhancing the measurement methods.

In order to solve the above-described problem, an ultrasonic diagnostic apparatus according to the present invention receives a reflection component of an ultrasonic pulse signal transmitted into a subject, and obtains an image of the subject based on a reception signal associated with the reception. In the ultrasonic diagnostic apparatus obtained, the transmission condition controller that performs the optimum value control processing of the transmission sound pressure while reading the information of the region of interest, and the collection of a plurality of the images related to the same part of the subject Rate changing means for actively changing the transmission frame rate of the ultrasonic pulse signal according to a sequence, scanning means for performing a scan with the ultrasonic pulse signal based on the transmission frame rate, and responding to the scan of the scanning means Receiving means for receiving the reflected component and processing the received signal, and processing for generating image data based on the received signal. Means for selecting image data for two frames obtained by the processing means, and difference calculating means for calculating an inter-frame difference between the selected two frames of image data. The component is configured to include a component in which the ultrasonic pulse signal is reflected by the ultrasonic contrast agent injected into the subject, and is a combination of optimal value control of transmission sound pressure and TIC measurement.

  In this case, preferably, the reflection component includes a component in which the ultrasonic pulse signal is reflected by an ultrasonic contrast agent injected into the subject. For example, the rate changing means is means for changing the transmission frame rate under a certain regularity. The rate changing means includes at least one of means for arbitrarily specifying the transmission frame rate by an operator and means for arbitrarily selecting from a plurality of preset transmission frame rates. May be.

  Further, receiving means for receiving the reflection component in response to the scan of the scanning means and processing the received signal, processing means for generating image data based on the received signal, and two frames obtained by the processing means It is also preferable to include a selection unit that selects the image data for the two frames and a difference calculation unit that calculates the inter-frame difference between the selected two frames of image data.

  According to the ultrasonic diagnostic apparatus according to the present invention, a configuration in which scanning is performed by actively changing the transmission frame rate of the ultrasonic pulse signal while collecting a plurality of images relating to the same part of the subject to which the contrast agent has been administered. In addition, since the main part is a configuration that calculates the difference between two images obtained by this scan, the physical property that the microbubbles that make up the contrast agent are disrupted by ultrasonic irradiation can be actively controlled. New information can be provided for quantification of information and differential diagnosis, and more detailed blood flow information can be provided by enrichment and enhancement of measurement methods.

  An embodiment of an ultrasonic diagnostic apparatus according to the present invention will be described with reference to the drawings.

[First Reference Example ]
A first reference example will be described with reference to FIGS. The ultrasonic diagnostic apparatus shown in this reference example has a configuration in which an ultrasonic contrast agent is administered to a subject and the blood flow state is observed from the degree of staining. In this case, the blood flow state can be observed in all the regions of interest, but in this reference example , an apparatus that identifies blood flow dynamics data based on the degree of contrast of the contrast agent flowing into the liver parenchyma or heart muscle and identifies the abnormal region Will be described.

FIG. 1 schematically shows the overall configuration of the ultrasonic diagnostic layer apparatus . The ultrasonic Doppler diagnostic apparatus shown in FIG. 1 includes an apparatus main body 11, an ultrasonic probe 12 connected to the apparatus main body 11, an operation panel 13, and an ECG (electrocardiograph) 14.

  The operation panel 13 is used to give various instructions and information from the operator to the apparatus main body 11, and is used to start the keyboard 13A, the trackball 13B, the mouse 13C, and transmission sound pressure optimization control described later. An “execute” button 13D is provided. The trackball 13B is used, for example, to function as a pointing device on a monitor screen and to set an ROI (region of interest) on an image. The keyboard 13A or the like can be operated to instruct switching between “B mode”, “CFM (Color Flow Mapping) mode”, and “PWD (Pulsed Wave Doppler) mode”. The CFM mode is a mode for displaying the blood flow state as a two-dimensional color image.

  The ultrasonic probe 12 is a device responsible for transmission / reception of an ultrasonic signal to / from a subject, and includes a piezoelectric vibrator such as a piezoelectric ceramic as an electrical / mechanical reversible conversion element. As a preferred example, a plurality of piezoelectric vibrators are arranged in an array and are provided at the probe tip to constitute a phased array type probe 12. As a result, the probe 12 converts the pulse drive voltage applied from the apparatus main body 11 into an ultrasonic pulse signal and transmits it in a desired direction within the subject, and also responds to the ultrasonic echo signal reflected by the subject. Convert to voltage echo signal.

  The ECG 14 is mainly used in contact with the body surface of the subject to obtain electrocardiographic waveform data of the subject.

  As shown in the figure, the apparatus main body 11 includes a transmission unit 21 and a reception unit 22 connected to the probe 12, a receiver unit 23 placed on the output side of the reception unit 22, a B-mode DSC (digital scan converter) 24, An image memory 25, a TIC operation unit 26, a Doppler unit 27, a display data synthesizer 28, and a display 29 are provided. An external output device 30 placed outside the diagnostic apparatus is connected to the TIC calculation unit 26. The external output device is constituted by, for example, a printer, a magnetic storage medium, a personal computer via a network, and the like. The apparatus main body 11 further includes a transmission condition controller 31 for controlling the transmission state of the ultrasonic signal based on the transmission unit 21 and a heartbeat detection unit 32 for receiving the ECG signal detected by the ECG 14.

  The configuration and operation of each circuit of the apparatus main body 11 will be further described.

  The transmission unit 21 includes a pulse generator, a transmission delay circuit, and a pulser. The pulse generator generates a rate pulse having a rate frequency fr [Hz] (period 1 / fr [second]) of 5 KHz, for example. This rate pulse is distributed to the number of transmission channels and sent to the transmission delay circuit. The transmission delay circuit is supplied with a timing signal for determining the delay time for each transmission channel. As a result, the transmission delay circuit gives a command delay time to the rate pulse for each channel. A rate pulse with a delay time is supplied to the pulser for each transmission channel. The pulser gives a voltage pulse to each piezoelectric vibrator (transmission channel) of the probe 12 at the timing of receiving the rate pulse. As a result, an ultrasonic signal is emitted from the probe 12. The ultrasonic signal transmitted from the ultrasonic probe 12 is focused in a beam shape within the subject, and the transmission directivity is set in the command scan direction.

The time interval of the scan executed by the transmission unit 21 is controlled by the transmission condition controller 31 as described later. The transmission condition controller 31 is a component that constitutes one feature .

  In the subject, beam forming is performed according to the delay time described above. The transmitted ultrasonic pulse signal is reflected by a discontinuous surface of acoustic impedance in the subject. This reflected ultrasonic signal is received again by the probe 12 and converted into an echo signal having a corresponding voltage amount. This echo signal is taken from the probe 12 into the reception unit 22 for each reception channel.

  The reception unit 22 includes a preamplifier, a reception delay circuit, and an adder in order from the input side. Each of the preamplifier and the reception delay circuit includes an amplifier circuit or a delay circuit for the reception channel. The delay time of the reception delay circuit is given as a signal of a delay time pattern in accordance with the desired reception directivity. For this reason, the echo signal is amplified by the preamplifier for each reception channel, given a delay time by the reception delay circuit, and then added by the adder. By this addition, the reflection component from the direction corresponding to the desired reception directivity is emphasized. A total ultrasonic beam for transmission and reception is formed by the combination of transmission directivity and reception directivity.

  The output terminal of the adder of the reception unit 22 reaches the display data synthesizer 28 via the receiver unit 23 and the B mode DSC 24 in order.

  Although not shown, the receiver unit 23 includes a logarithmic amplifier, an envelope detector, and an A / D converter. In the case of an apparatus that performs the harmonic imaging method, the receiver unit 27 is equipped with a band-pass filter that passes only a high-frequency component that is, for example, twice the transmission frequency of the ultrasonic signal. By this receiver unit, echo data in a direction to which reception directivity is given is formed in a digital amount and sent to the B mode DSC 24.

  The B mode DSC 24 converts the echo data from the raster signal sequence of the ultrasonic scan into a raster signal sequence of the video format and sends it to the display data synthesizer 28.

  The image memory 25 is connected to the B-mode DSC 24 and includes a memory element for recording a processing signal of the DSC (either a raster signal string of an ultrasonic scan or a raster signal string of a video format) and a writing / reading control circuit thereof. The echo data recorded in the memory element is read out in units of frames in response to an operator instruction during or after imaging. The read data is sent to the display 29 via the B mode DSC 24 and the display data synthesizer 28 and displayed.

  Further, the read output terminal of the image memory 25 is also connected to the TIC arithmetic unit 26 so that read data from the memory can be taken into the arithmetic unit 26. The TIC calculation unit 26 includes a work memory and a calculation circuit such as a CPU, calculates TIC (Time Intensity Curve) data from echo data read into the work memory, and outputs the calculated data to the display data synthesizer 28 and as necessary. Accordingly, it can output to the external output device 30. As a result, the TIC data is displayed or output on the display 29 and the external output device 30.

  The Doppler unit 27 receives the addition echo signal in the receiver unit 23. Although not shown, the unit 27 includes a quadrature detector, a clutter removal filter, a Doppler shift frequency analyzer, an arithmetic unit such as an average speed, a DSC, a color processing circuit, and the like, and a Doppler shift frequency, that is, velocity information of blood flow. And its power information can be obtained as color flow image data. The color flow image data (CFM data) is subjected to processing such as noise cancellation by a DSC built in the Doppler unit 27, and its scanning method is converted and sent to the display data synthesizer 28. The color flow image data can be sent to the image memory 25 for storage.

  The heart rate detection unit 32 receives the ECG signal supplied from the ECG 14 and sends the electrocardiogram waveform data to the display data synthesizer 28 for display, while synchronizing the heart image with the electrocardiogram waveform. A trigger signal for synchronization is created, and this trigger signal is sent to the transmission condition controller 31.

  The display data synthesizer 28 receives B mode image data (grayscale image) sent from the B mode DSC 24, CFM mode image data (color flow image) sent from the Doppler unit 27, and sent from the heart rate detection unit 32. The image data of one frame is reconstructed by processing such as arranging or superimposing the incoming electrocardiogram waveform, the calculation data of the TIC calculation unit 26, and / or desired setting parameters. The frame image data is sequentially read out by the display device 29. In the display 29, the image data is converted into an analog quantity by a built-in D / A converter, and a tomographic image of the tissue shape of the subject is displayed on a display such as a TV monitor.

  Further, the transmission condition controller 31 includes an A / D converter that receives operation data from the operation panel 13 and a CPU (central processing unit), and a memory connected to the CPU. A program for controlling transmission conditions is stored in advance in the memory. The CPU is connected to the operation panel 13, the receiver unit 23, the heart rate detection unit 32, the transmission unit 21, and the TIC calculation unit 26 through an interface, and outputs a control signal by performing processing shown in FIG. To do.

(Transmission sound pressure optimization control)
One of the preferred modes of use of this apparatus is to operate in a mode in which a contrast echo method is performed by administering an ultrasonic contrast agent to a subject. FIG. 2 shows an example of transmission condition optimization control performed by the transmission condition controller 31 under the contrast echo method. The transmission condition controller 31 receives the ECG synchronization signal S _ecg from the heartbeat detection unit 32 and performs optimization control to be described later on the transmission ultrasonic beam signal continuously or intermittently.

Here, the transmission sound pressure is selected as the transmission condition, and the transmission sound pressure is controlled to be optimized by directly raising and lowering the transmission drive voltage applied to the probe 11, but the reference example is not necessarily limited to this. Not. A parameter that can change the sound field sound pressure of the diagnostic region as a result may be used. For example, the number of transmission drive elements in the probe 11 may be changed.

  Now, as an initial value, it is assumed that the transmission sound pressure is controlled to the same value as in the conventional diagnosis. Such an initial value is, for example, a transmission sound pressure of about 1 M Pascal, and is known to be a level sufficient to eliminate the microbubbles of the contrast medium. When the contrast agent administered to the subject reaches the diagnosis site, the intensity of the echo signal usually increases naturally. However, if the transmitted sound pressure is high, this does not happen, and it flows into the diagnosis site. Since the bubble that disappears disappears instantaneously, the intensity of the echo signal is low. An example of the qualitative relationship between the transmission sound pressure and the remaining number of bubbles is shown in FIG.

Therefore, the transmission condition controller 31 determines the start of transmission sound pressure control as shown in FIG. 2 (step 101 in FIG. 2). In this reference example , this determination is made by detecting whether or not the “execute” button 13D on the operation panel 13 is pressed by the controller 31. When this determination is YES (transmission sound pressure start), the echo signal Secho (echo signal beamformed) is read from the receiver unit 23, and its signal value (amplitude, intensity) is set to Sa (step 102). The value of the echo signal Secho read here is, for example, an integral value of the echo signal of the entire image to be displayed.

Next, the controller 31 sends a sound pressure control signal S _sd for lowering the transmission sound pressure by a predetermined value ΔD to the transmission unit 21 (step 103). In response to the sound pressure control signal S _sd , the transmission unit 21 decreases the drive voltage from, for example, the pulser corresponding to a predetermined sound pressure reduction value. As a result, the sound pressure value of the sound field at the diagnostic site irradiated from the probe 11 is lowered by the specified value ΔD. Under the reduced sound pressure, an ultrasonic reflection signal is received via the probe 11. The reflected signal is subjected to reception processing by the receiving unit 22, and an electric quantity echo signal is generated by the receiver unit 23.

The echo signal S _echo is read again by the transmission condition controller 31, and the signal value is recognized as Sb (step 104). When receiving the echo signal after the sound pressure reduction, as shown in FIG. 3, the degree of disappearance of the contrast agent bubbles is suppressed, or at least the same as the previous state. For this reason, the intensity of the ultrasonic reflection signal from the diagnosis site increases or decreases by the amount corresponding to the decrease in the sound pressure, so that the signal value of the echo signal increases or decreases (in some cases it may not change). is there).

Therefore, the transmission condition controller 31 determines whether or not Sa> Sb for the signal values Sa and Sb read so far (step 105). If this determination is NO, that is, Sa ≦ Sb, it is recognized that the optimum value of the transmission sound pressure has not yet been reached, and the signal value Sb after the sound pressure reduction is replaced with the signal value Sa before the sound pressure reduction. (Step 106) Then, it returns to the process of Step 103 mentioned above. For this reason, the transmission sound pressure is again lowered by the predetermined value ΔD, and a determination is made as to whether Sa> Sb as described above (steps 103 to 105). This series of processing is repeated until Sa> Sb.

  If the transmission sound pressure has reached a level at which bubbles do not disappear while repeating the transmission sound pressure reduction and signal value comparison processes described above, the echo signal will drop the next time the transmission sound pressure is lowered. Since it starts, Sa> Sb (YES) is satisfied in the determination step 105. In other words, since the sound pressure used for transmission when Sa> Sb is determined is the optimum sound pressure, the sound pressure is stored (step 107), and the optimization process is terminated.

  For this reason, when the operator presses the “execute” button 13D of the operation panel 13, the above-described transmission sound pressure optimization control is executed under ECG synchronization. Therefore, optimization control can be started manually in accordance with the contrast agent administration timing, and the start timing can be easily set. It is also easy for the operator to select whether or not to perform optimization.

  By this optimization, the sound pressure provided by the ultrasonic beam signal becomes a level at which the bubbles of the contrast agent flowing into the diagnostic site are hardly lost. For this reason, the echo signal with the highest intensity can be obtained, and the contrast effect is remarkably improved. In particular, even when an organ substance having a slow blood flow velocity or a relatively thin blood vessel is a target for diagnosis, the bubbles of the contrast medium that flow in are ultrasonicated one after another before confirming the contrast enhancement of the contrast medium. The situation of disappearing due to irradiation can be reliably avoided.

  Therefore, when the contrast echo method is performed using the transmission sound pressure (transmission condition) optimized as described above, an echo signal having a significantly higher S / N ratio than that of the conventional method can be obtained. It is possible to provide a B-mode image that fully enjoys the advantage of the echo luminance enhancement effect due to the agent, or an image in which a color blood flow image in the CFM mode is superimposed on the B-mode image.

  In the comparison process of the echo signal values Sa and Sb before and after the sound pressure reduction described above, the echo signal used for this process is not limited to the aspect using the echo signal (integral value) for the raster of the entire image as described above. . In addition to this, for example, echo signals for typical transmission rasters (for example, five rasters at the center of the image) may be used, thereby reducing the amount of calculation. In addition, the echo signal of the raster in the ROI designated in advance by the operator may be used, so that the local part considered to be the most important for diagnosis can be designated, and the optimum transmission condition can be automatically set for the part. Therefore, there is a further advantage that the optimal or control system is further improved.

[Second Reference Example ]
A second reference example of the ultrasonic diagnostic apparatus will be described with reference to FIG. In this reference example , the transmission condition optimization control described above is applied to the pulse Doppler (PWD) method.

The ultrasonic diagnostic apparatus shown in FIG. 4 includes a PWD mode circuit system in place of the Doppler unit related to the CFM mode in the apparatus configuration shown in FIG. 1, and omits an ECG system circuit and an external output circuit. It is configured.

  As a circuit system in the PWD mode, a sample volume Doppler controller 41 connected to the operation panel 13 is provided, and a range gate circuit 42, a quadrature phase detector 43, and a sample / hold circuit 44 arranged on the output side of the controller 41. , BPF 45, A / D converter 46, and frequency analyzer 47. Similarly to the transmission condition controller 31, the quadrature detector 43 receives the output of the beam forming adder of the receiver unit 23.

  For this reason, when the operator uses the operation panel 13 to set a sample volume such as an X mark ROI in a part of the scan image, position information for designating the volume part is given to the controller 41.

  As a result, a position signal corresponding to the position information is transferred from the controller 41 to the range gate circuit 42. The range gate circuit 42 generates a range gate signal corresponding to the designated sample volume and sends it to the sample / hold circuit 44. By this sample / hold circuit 44, only the signal corresponding to the designated sample volume in the phase detection signal output from the quadrature phase detector 43 is sampled. This sample signal has its high-frequency and low-frequency noises cut by the BPF 45, further converted into a digital signal by the A / D converter 46, and sent to the frequency analyzer 47. That is, in the case of this PWD mode, the signal given to the frequency analyzer 47 at a certain moment is a signal of only the designated sample volume. The frequency analyzer 47 analyzes the frequency of the phase detection data string at the designated sample volume position, and outputs spectral data that changes from time to time to the display data synthesizer 28. Thereby, the Doppler information of the designated sample volume position is displayed as a spectrum together with the B mode image.

On the other hand, as in the case of the first reference example , the transmission condition controller 31 can perform the optimization control of the transmission sound pressure as the transmission condition when the operator presses the execution button 13D at an arbitrary timing. .

Thus, also in the PWD mode, the transmission conditions can be suitably optimized as in the first reference example . In this PWD mode, since the input signal to the frequency analyzer is only one value of the sample volume at a certain moment, such optimization control functions very effectively.

[Third Reference Example ]
A third reference example of the ultrasonic diagnostic apparatus will be described with reference to FIGS. This reference example relates to display of transmission sound pressure (power) based on transmission condition optimization control.

The ultrasonic diagnostic apparatus shown in FIG. 5 includes a transmission sound pressure display processor 51 interposed between the transmission condition controller 31 and the display data synthesizer 28 in addition to the configuration of FIG. 4 described above. The transmission sound pressure display processor 51 includes a CPU, for example. The processor 51 inputs the transmission sound pressure value set by the transmission condition controller 31 in real time, and displays numerical data and / or graph data representing the transmission sound pressure value that is automatically controlled from time to time. To send. Thereby, it is possible to recognize at a glance how the transmission sound pressure changes while the transmission sound pressure is optimized and the final set value.

A processing example of the transmission sound pressure display processor 51 in this reference example is shown in FIGS. In the case of FIG. 6A, the initial value of the transmission sound pressure is displayed on the upper right side of the screen, and the transmission sound pressure value B during the optimization control changing from the initial value A is displayed on the right side via the arrow. Update and display in real time. In the case of FIG. 5B, the time change graph C from the initial value of the transmission sound pressure and the transmission sound pressure value D during the optimization control changing in real time are displayed on the upper right of the screen.

  By displaying in this way, the state of change from the initial value of the transmission sound pressure and the lowered current transmission sound pressure become obvious to the operator, which can contribute to smooth operation and the like.

The display of the transmission sound pressure value can also be applied to the configuration described in the first reference example described above.

[ First Embodiment]
The first embodiment of the ultrasonic diagnostic apparatus according to the present invention will be described with reference to FIGS. 7-8. This embodiment particularly relates to a combination of transmission sound pressure optimization control and TIC measurement. Preferably, the ultrasound contrast agent is administered by a continuous infusion method.

  As already explained, when the TIC measurement under the contrast echo method is performed in such a manner that the contrast agent flows into the region of interest and the luminance increases, the measurement parameter has a peak value of luminance change, an increase. It is important to reduce the brightness (washout) from the peak of the speed and brightness change. When the transmission sound pressure optimization control according to the above-described embodiment is performed at the time of TIC measurement that measures a parameter mainly based on such a change, it takes a period during which the transmission sound pressure is changed by obtaining an optimum value. A situation occurs in which information on luminance change (at least accurate information) cannot be obtained. Accordingly, it is a further object of the ultrasonic diagnostic apparatus of the present embodiment to reliably avoid such a situation and perform accurate and stable TIC measurement.

  In order to achieve this object, the transmission condition controller 31 provided in the ultrasonic diagnostic apparatus shown in FIG. 7 executes the process of FIG. 8 and displays the display related to the TIC measurement start timing and the optimization end by the TIC calculation unit 26. It can be controlled. Other structural requirements are the same as or similar to the configuration shown in FIG.

  As shown in FIG. 8, the transmission condition controller 31 commands scanning by beam transmission of the normal sound pressure value as an initial value, storing echo data for each frame in the image memory 25, and displaying by the display 29 ( Step 111). As a result, the display of the blood flow color image in which the CFM image is superimposed on the B-mode image, for example, on the display 29 is started in correspondence with the normal transmission sound pressure value used conventionally. The scan, storage of echo data, and image display are subsequently continued almost in real time except when the image is frozen.

  Next, the controller 31 reads operation information from the operation panel 13 and obtains information such as whether TIC measurement is performed in real time with scanning or under freezing (step 112). Similarly, it is determined whether an operator has set, for example, a graphical ROI (region of interest) at an arbitrary position on the displayed color image (step 113), and when it can be determined that the ROI has been set, Information such as the ROI position and the ROI size is read (step 114).

  Thereafter, the controller 31 sequentially executes the processes of steps 115 to 120. First, whether or not to start transmission sound pressure optimization control as a transmission condition is determined based on a signal from the execution button 13D on the operation panel (step 115). When optimization is started, transmission sound pressure optimization control processing is executed (step 116). This process is the same as steps 102 to 107 in FIG. Thereby, the optimum transmission sound pressure at which the maximum echo signal is reflected from the bubbles of the ultrasonic contrast agent is automatically set. After this, the transmission controller 31 sends the data Da indicating the end of optimization and the optimized sound pressure value data Db to the display data synthesizer 28 (step 117). Therefore, the optimization end mark and the optimum sound pressure value are superimposed and displayed as numerical data on a part of the screen of the display device 29.

  Next, the controller 31 momentarily commands the transmission unit 21 to transmit ultrasonic waves with a sound pressure (high sound pressure) that is high enough to eliminate all the bubbles of the contrast medium (step 118). As a result, almost all of the microbubbles in the vicinity of the scan surface that is currently being scanned disappear instantaneously.

  When this is done, the controller 31 immediately instructs the transmission unit 21 to set the transmission sound pressure and return to the optimum sound pressure value to perform ultrasonic transmission (step 119). In other words, the scanning surface and its nearby bubbles are instantaneously destroyed by high sound pressure transmission, and then immediately returned to the optimum sound pressure transmission state. Inflow. Since the sound pressure of the ultrasonic beam applied to the new inflowing bubble is returned to the optimized value, the disappearance of the bubble is small and the maximum ultrasonic echo is generated again.

In this state, the controller 31 then determines whether to perform TIC measurement in real time or in a frozen state based on the read information in step 112. If it is determined that measurement is to be performed in real time (YES), the process proceeds to step 121, and the start timing signal S _{st and} ROI information (position, size) S _ROI permitting TIC measurement and display of the result are sent to the TIC calculation unit 26. . In response to the signal S _st, TIC arithmetic unit 26 reads the echo frame data stored over time in the image memory 25 through the B-mode DSC 24, for operation on the specified ROI position various parameters mentioned above. The calculation result is sent to the display data synthesizer 28 and the external output device 30. As a result, the real-time blood flow color tomogram and the graph and / or numerical data representing the TIC measurement result are displayed on the screen of the display 29 in a substantially real-time manner, for example, in a divided manner.

On the other hand, when it is determined that the TIC measurement is performed in the image freeze state (step 120: NO), the process proceeds to step 122, and the scan state with the currently set optimum sound pressure is continued for a certain time. The width of this fixed time is set to a value that can collect echo data necessary for TIC measurement. During this fixed time, a fixed number of frame echo data is collected and stored in the image memory 25. When the predetermined time has elapsed, the controller 31 sends the start timing signal S _st and the ROI information S _ROI to the TIC arithmetic unit 26 as in the case of step 121 described above, and also freezes the signal S _fz that prohibits further transmission. Is sent to the transmission unit 21. As a result, the tomographic image displayed on the display device 29 is frozen. At the same time, the TIC calculation unit 26 reads the echo data for a plurality of frames stored in the image memory 25 during the waiting period of the predetermined time, and calculates the various parameters described above with respect to the designated ROI position. The calculation result is sent to the display data synthesizer 28 and the external output device 30. Thereby, the blood flow color tomographic image of the freeze and the graph and / or numerical data representing the TIC measurement result are displayed on the screen of the display device 29 in substantially real time, for example, in a divided manner.

As described above, according to the present embodiment, a method of instantaneously irradiating an ultrasonic beam with a high sound pressure instantaneously disappears almost all of the microbubbles in the vicinity of the scan surface and returns it to the optimum sound pressure is used. ing. Therefore, since the state of the contrast medium flowing back into a clean state without any bubbles can be observed, it is possible to create a state equivalent to performing ultrasonic transmission with the optimum sound pressure from the beginning. TIC measurement in real time or under freeze can be performed with high accuracy and stability.

  That is, it is possible to reliably prevent the occurrence of a situation in which information on luminance change (at least accurate information) due to the contrast agent cannot be obtained during a period when the transmission sound pressure is changed by obtaining the optimum value. Of course, since the timing of starting the TIC measurement is accurately managed, the received echo data during the optimization control of the transmission sound pressure does not enter or participate in the TIC measurement.

  In addition, according to the present apparatus, the TIC measurement mode can be selected between the real-time mode and the freeze mode, which is convenient for measurement.

  Furthermore, in this apparatus, ROI setting for TIC measurement, optimization control of transmission sound pressure, scanning with optimum sound pressure, and TIC measurement are all automated in a series of operations. For this reason, since the operator has little work effort and excellent work efficiency, an improvement in patient throughput can be expected. Of course, the ROI setting can be set to be executed every time the TIC is measured.

[ Second Embodiment]
The second embodiment of an ultrasonic diagnostic apparatus according to the present invention with reference to FIGS. 9 to 12 will be described. The ultrasonic diagnostic apparatus of the present embodiment is characterized in that an image related to the blood flow inflow amount is obtained using the physical properties of the ultrasonic contrast agent. For this image acquisition, an imaging method called a so-called flash echo method is used. As described above, the flash echo method collects high-intensity echo signals by erasing minute air bubbles (contrast agent) that are dense without breaking into organs by intermittently transmitting ultrasonic beams as described above. It is. That is, unlike the previous embodiments, the technique of this embodiment is intended to obtain an efficient diagnostic image by actively collapsing microbubbles forming a contrast agent with a certain regularity. It is. The ultrasound contrast agent is preferably administered by a continuous injection method, and a contrast echo method using this contrast agent is performed.

  An ultrasonic diagnostic apparatus that implements this method is shown in FIG. The transmission condition controller 31 provided in the ultrasonic diagnostic apparatus additionally has a function of controlling a transmission frame rate and giving a command for loop reproduction to the B mode DSC 24 and the image memory 25. The operation panel 13 includes a freeze button 13E. Other configurations are the same as or similar to those in FIG.

  In the case of an ultrasonic diagnostic apparatus conventionally used, the frame rate (transmission time interval) is usually controlled to be constant during observation, for example, as shown in 10 (a). Of course, when the depth of field and the scanning line density are changed, the frame rate is also changed, but is usually maintained at a constant interval under a certain scanning condition. On the other hand, in the case of the ultrasonic diagnostic apparatus of this embodiment, the transmission condition controller 31 changes the frame rate as shown in FIG. 10B, for example, even under a certain scanning condition. In this example, the time interval (frame rate) for obtaining one frame of image data increases with time, such as “0.1 second, 0.2 second, 0.3 second,..., 1.0 second”. As described above, it is preset by an execution program of the CPU.

  It should be noted that the frame rate interval may be controlled to be shortened with time. In addition, when the ultrasonic contrast agent is administered by the continuous injection method, the sequence shown in FIG. 10B may be repeated.

Here, the principle of obtaining an image representing the amount of blood flow by changing the frame rate will be described. FIG. 11A schematically shows the moment when the bubbles in the effective sound field that cross the blood vessel disappear due to the ultrasonic irradiation. Immediately after this disappearance, the contrast medium (bubbles) starts to flow into the sound field. When the next ultrasonic irradiation is performed within a relatively short time, the amount of bubbles flowing into the sound field is small as shown in FIG . When the flash echo method is performed in this bubble state, since the amount of bubbles is small, the intensity of the echo signal is relatively small. However, when the interval (frame rate) of ultrasonic irradiation is increased, the amount of bubbles flowing in until the irradiation increases, for example, as shown in FIG.

  For this reason, when the time until the bubbles are fully filled in the sound field (effective sound field) effective for eliminating bubbles by ultrasonic irradiation is defined as a saturation time Tfull, an interval (frame) longer than the saturation time Tfull is set. Even if scanning is performed at a rate, the intensity of the echo signal obtained thereby is constant.

  This relationship is illustrated in FIG. 12 with the horizontal axis representing the frame rate and the vertical axis representing the echo signal intensity. The figure shows a comparative example of two blood vessels 1 and 2 (data 1 and data 2). The saturation time Tfull of the blood vessel 1 is 0.2 seconds, and the saturation time Tfull of the blood vessel 2 is 0.4 seconds. From this, it can be seen that the blood flow rate of the blood vessel 1 is higher than that of the blood vessel 2 and the signal intensity is high, and therefore the blood flow rate is also large.

Based on such a principle, the transmission condition controller 31 changes the frame rate according to the sequence of FIG. 10B, for example. A plurality of frames of image data (B-mode image and CFM image image data) obtained in this sequence are stored in the image memory 25 as described above. Therefore, after the series of transmissions is completed, the controller 31 stops scanning in response to an operator signal from the freeze button 13E, and then gives a command signal S _dp for instructing the loop reproduction to the image memory 25 and the DSC 24. . As a result, a B-mode image in which the luminance gradually increases or a tomographic image in which a color blood flow image (CFM image) is superimposed on the B-mode image is loop-reproduced on the screen of the display device 29. A blood vessel with a large blood flow rate becomes brighter and faster, so that the blood flow amount can be measured and observed by this difference.

The transmission condition controller 31 (time interval has accumulated bubbles) time intervals many seconds, that is, for example numerical data or display data D _cg such graph data data synthesizer representing the sequence shown in FIG. 10 (b) 28 to send. For this reason, since information on this time interval is also reproduced on the loop reproduction screen, information indispensable for the operator to judge the magnitude of the blood flow is also obtained, and an efficient diagnosis is possible.

A modification of the second embodiment will be described. Considering the ability to display the blood flow, it is important to change the frame interval under a certain regularity, but the regularity itself may depend on any function. For example, as shown in FIG. 13, the frame interval is 0.1 second, 0.1 second, 0.1 second, 0.1 second, 0.2 second, 0.2 second, 0.2 second, 0.2 second. A sequence in which the same interval is repeated four times, such as. The pixel values of the four frame images obtained as a result may be averaged, and one frame image data composed of the average value may be displayed as a representative image at the same frame interval.

Another modification relates to a method for setting the frame interval. The transmission condition controller 31 performs the process shown in FIG. The controller 31 reads information from the panel and keyboard associated with the operation of the operation panel 13 by the operator (step 131), and the scan mode according to the second embodiment described above (a mode in which the frame rate is actively changed). Is identified (step 132). If such a scan mode has been commanded (step 133, YES), then a frame interval change pattern is set and stored (steps 134, 135). The change pattern can be set by the operator operating the operation panel each time, but a table prepared with a plurality of change patterns stored in advance in the memory is displayed on the screen, It is convenient to select.

[ Third Embodiment]
A third embodiment of the ultrasonic diagnostic apparatus according to the present invention will be described with reference to FIGS. This embodiment relates to generating a difference image of a blood flow image.

  The ultrasonic diagnostic apparatus in FIG. 15 includes a difference calculation unit 53. The arithmetic unit 53 reads out two pieces of image data from the image memory 25 under the command signal Ddif from the transmission condition controller 31, and calculates the difference for each pixel value. The frame data composed of the difference values is displayed via the B mode DSC 24. In addition to the freeze button 13E, the operation panel 13 is equipped with a difference start button 13F so that the operator can operate it.

The transmission condition controller 31 generally performs the processing shown in FIG . First, after the echo data is captured by scanning, the operator presses the freeze button 13E. When the freeze command is input (step 161), the controller 31 stops scanning of the transmission unit 21, while sending the freeze signal Sf to the DSC 24 and the image memory 25 to display the image captured so far (step 162). . Next, the operator uses the trackball or the like to select two images A and B to be used for the difference calculation on the display screen (step 163). This display image displays data indicating how many seconds the image has been scanned at a frame interval (the time during which bubbles are accumulated).

  After selecting the image, the controller 31 detects whether or not the difference start button 13F has been pressed by the operator (step 164). When this detection is made, the controller 31 sends a difference start signal Sdif to the difference calculation unit 53, causing the unit 52 to calculate the luminance value difference between the selected images A and B for each pixel. The difference image data is output to the DSC 24 (step 165). Thus, after freezing, the image recorded in the image memory 25 can be read arbitrarily, and the difference image can be created and displayed.

  The effect by this difference calculation has a remarkable thing which is not in the past. As can be seen from the graph of the frame interval versus echo signal intensity illustrated in FIG. 17, the curves of the blood vessels 1 and 2 have substantially the same signal value (stain luminance) when the frame interval of a sufficiently long time is taken. Converge to. In the case of the figure, it is a range of 0.4 seconds or more on the horizontal axis indicating the frame interval. The difference between the two curves lies in the bubble supply rate up to its 0.4 second frame interval. If transmission according to the flash echo method is performed at intervals of 0.2 seconds, the blood vessel 1 exhibits a greater degree of shadow (see points 1A and 2A in the figure). For this reason, when a difference is calculated between an image with a frame interval of 0.4 seconds and an image with a 0.2 second interval, there is almost no luminance difference between the points 1A and 1B of the blood vessel 1. The value is canceled and almost zero. However, in the case of the blood vessel 2, since there is a difference between the points 2A and 2B, this difference is imaged.

  Eventually, there is a unique advantage that blood flow information in a specific blood flow velocity range can be extracted and displayed by performing difference processing between images with appropriate frame intervals as described above. For this display, loop reproduction or the like is suitable.

  Note that the image obtained by continuously performing the difference processing is stored again in the image memory 25 or stored in another memory, and the TIC data regarding the plurality of difference images is stored in the TIC calculation unit 26. It can also be calculated. Also, the difference calculation and the TIC calculation may be performed in real time.

  Moreover, the difference calculation mentioned above is not limited to the method implemented as a post-process in a freeze state, You may implement in real time. For example, image data obtained in real time from the DSC 24 in accordance with scanning is read into the difference calculation unit 53 at predetermined frame intervals, and when the difference data is prepared, the difference is performed for each pixel, and the difference result is obtained from the DSC 24. For example, it may be displayed together with the tomographic image in a divided manner.

  According to this ultrasonic diagnostic apparatus, for example, in a state where an ultrasonic contrast agent is administered to a subject, the transmission power condition such as transmission sound pressure is adaptively controlled so that the reception signal is maximized. In the method, it is possible to remarkably suppress the disappearance of the bubbles that the contrast medium always has in the transmission power condition, and to obtain a high-quality tomographic image with the highest contrast effect under the optimized transmission power condition. As a result, it is possible to make various image processing functions more effective, and it is possible to observe the blood flow dynamics of the blood vessels and the hemodynamics at the organ parenchyma level by detecting perfusion, as well as to quantitatively evaluate and differentially diagnose them. And it can be performed with high accuracy.

  Further, according to the ultrasonic diagnostic apparatus of the present application, the transmission power condition is adaptively controlled so that the reception signal is maximized in a state where the ultrasonic contrast agent is administered to the subject, and thereafter the transmission power condition is temporarily increased. Since the transmission power condition is raised and then the optimized transmission power condition is restored to measure the luminance change curve (TIC) data of the received signal over time, the optimum transmission power condition such as transmission sound pressure is optimized. The contrast echo method can be surely and stably implemented by securing the most contrast effect. At the same time, from the optimization of the transmission power condition to the TIC measurement can be performed automatically and consistently in one execution of the contrast echo method, the operational effort of the operator is reduced. Excellent operating efficiency and contributes to improved patient throughput.

  Each embodiment mentioned above and its modification are only illustrations, and do not intend to limit the scope of the present invention. The scope of the present invention is determined according to the description of the scope of claims, and various forms of ultrasonic diagnostic apparatuses can be implemented without departing from the scope of the present invention.

The block diagram which shows the 1st reference example of an ultrasound diagnosing device . The schematic flowchart which shows the example of control of a transmission condition controller. The figure which shows qualitatively the relationship between transmission sound pressure and the number of the bubbles (ultrasonic contrast agent) which remain without disappearing by ultrasonic irradiation. The block diagram which shows the 2nd reference example of an ultrasound diagnosing device . The block diagram which shows the 3rd reference example of an ultrasound diagnosing device . The figure which shows two examples regarding the display of transmission sound pressure. 1 is a block diagram showing a first embodiment of an ultrasonic diagnostic apparatus according to the present invention. The schematic flowchart which shows the example of control of a transmission condition controller. The block diagram which shows 2nd Embodiment of the ultrasonic diagnosing device which concerns on this invention. The sequence explaining the control example of the frame interval of this invention compared with a prior art. The figure explaining the space | interval of a flame | frame and the mode of a collapse of a micro function. The graph explaining the qualitative relationship between a frame space | interval and echo signal strength. The figure which shows the modification of the sequence of a frame interval. 4 is a rough flowchart showing a setting process to a scan mode for changing a frame interval. The block diagram which shows 3rd Embodiment of the ultrasonic diagnosing device which concerns on this invention. The rough flowchart which shows the example of control of the transmission condition controller for a difference image calculation. The graph which shows the qualitative relationship between the frame interval and echo signal strength for demonstrating the effect of a difference image.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Apparatus main body 12 Ultrasonic probe 13 Operation panel 21 Transmission unit 22 Reception unit 23 Receiver unit 24 B mode DSC
25 Image memory 26 TIC arithmetic unit 27 Doppler unit 28 Display data synthesizer 29 Display 31 Transmission condition controller 43 Doppler unit 41 Doppler controller 42 Range gate circuit 44 S / H circuit 46 A / D converter 47 Frequency analyzer 51 Transmission sound Pressure display processor 53 Difference calculation unit

Claims (1)

In an ultrasonic diagnostic apparatus that receives a reflection component of an ultrasonic pulse signal transmitted into a subject and obtains an image of the subject based on a reception signal associated with the reception,
A transmission condition controller that performs optimum value control processing of the transmission sound pressure while reading the information of the region of interest;
Rate changing means for actively changing the transmission frame rate of the ultrasonic pulse signal according to a sequence while collecting a plurality of the images relating to the same part of the subject;
Scanning means for performing scanning by the ultrasonic pulse signal based on the transmission frame rate ;
Receiving means for receiving the reflected component in response to the scanning of the scanning means and processing the received signal;
Processing means for generating image data based on the received signal;
Selection means for selecting image data for two frames obtained by the processing means;
Difference calculating means for calculating an inter-frame difference between the selected two frames of image data,
The reflection component is configured to include a component in which the ultrasonic pulse signal is reflected by an ultrasonic contrast agent injected into the subject.
An ultrasonic diagnostic apparatus characterized by combining optimal value control of transmission sound pressure and TIC measurement.

Images