JP4131878B2 - Ultrasonic diagnostic equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is mainly carried out for the purpose of administering an ultrasound contrast agent to a subject, observing blood flow dynamics in the blood vessel region, hemodynamics at the organ parenchyma level by detecting perfusion, and quantitative evaluation thereof. The present invention relates to an ultrasonic diagnostic apparatus having various image processing functions.
[0002]
[Prior art]
There are various apparatuses as medical applications of ultrasound, and the mainstream is an ultrasound diagnostic apparatus that obtains a tomographic image of a soft tissue of a living body using an ultrasonic pulse reflection method. This ultrasonic diagnostic apparatus displays a tomographic image of a tissue by a non-invasive examination method, such as an X-ray diagnostic apparatus, an X-ray computed tomography (CT) apparatus, a magnetic resonance imaging (MRI) apparatus, and a nuclear medicine diagnostic apparatus. Compared to other diagnostic devices, real-time display is possible, the device is small and inexpensive, there is no radiation exposure such as X-rays, safety is high, and blood flow imaging is possible by ultrasonic Doppler method Have. For this reason, ultrasonic diagnosis is widely performed in the heart, abdomen, mammary gland, urology, and gynecology. Such ultrasonic diagnosis can be obtained by real-time display of heart beats and fetal movements by a simple operation of simply placing the ultrasonic probe on the body surface, and it is highly safe and repeatable. In addition to being able to perform inspections, it is easy to perform inspections by moving the diagnostic device to the bedside.
[0003]
By the way, in the examination of, for example, the heart and abdominal organs, blood flow dynamics are being evaluated by an ultrasonic diagnostic apparatus in which an ultrasonic contrast agent is injected from a vein. Since contrast agent injection from a vein is less invasive, diagnosis by this evaluation method of blood flow dynamics is becoming widespread. Many of the contrast agents use microbubbles as a reflection source, and the contrast effect increases if the injection amount / concentration is high. However, due to the nature of the bubbles, there is a problem that the contrast effect time is shortened by ultrasonic irradiation.
[0004]
In recent years, a persistent / pressure-resistant contrast medium has been developed, but it is feared that continuation of the contrast medium in a subject for a long time will increase invasiveness.
Considering the subject site in the clinic, the contrast medium is supplied to the region of interest one after another by the blood flow. Therefore, even if bubbles disappear due to one ultrasonic irradiation, it is new at the time of the next transmission. If bubbles are present in the same region of interest, the contrast effect could be maintained.
[0005]
However, taking into account the fact that ultrasonic transmission / reception is usually performed thousands of times per second and the presence of blood flow dynamics of organs with a slow blood flow velocity or relatively thin blood vessels, the brightness of contrast agents on these diagnostic images It can be fully expected that the bubbles disappear one after another before confirming the enhancement and the contrast effect is instantly attenuated.
[0006]
The most basic purpose of diagnosis using a contrast agent is to know the presence or absence of blood flow at the diagnosis site by examining the presence or absence of brightness enhancement by the contrast agent. Diagnosis further advanced is to observe the temporal change of the spatial distribution of the contrast medium at the diagnostic site from the extent of the brightness change and the degree of brightness enhancement, and from the contrast medium injection to the region of interest (ROI). The time until it arrives at the time, the time-dependent change in echo intensity (TIC: Time Intensity Curve) within the ROI, or the maximum luminance, etc. are obtained.
[0007]
Diagnosis by the contrast echo method as described above becomes more effective by a technique called harmonic imaging. Harmonic imaging is an imaging technique in which only non-linear behavior caused by ultrasonic excitation of microbubbles is separated and detected. Since biological organs are relatively less likely to cause nonlinear behavior, the contrast medium can be observed with a good contrast ratio.
[0008]
In addition, for the phenomenon in which microbubbles disappear due to ultrasonic irradiation as described above, an imaging technique called flash echo imaging (hereinafter referred to as “FEI”), transient response imaging (Trangient Response Imaging), or the like. It has been reported that brightness enhancement can be improved. About flash echo imaging, it is described in the reference "67-95 Examination of Flash Echo Imaging (1)", Naohisa Kamiyama, Yoshitaka Tsuji, 67th Annual Meeting of the Japanese Society of Ultrasonic Medicine, June 1996. ing. In principle, this imaging method uses conventional continuous transmission (scanning) such as several tens of frames per second to intermittent transmission such as one frame per several seconds, so that microbubbles that are densely packed without breaking are once This is a method of trying to obtain a high echo signal. The invention according to this technique is described in Japanese Patent Application No. 7-89443 (filing date: April 14, 1995) which is filed by the same applicant as the present invention.
[0009]
[Problems to be solved by the invention]
By the way, it is desirable for observation with continuous irradiation such as the harmonic imaging method to lower the transmission sound pressure as much as possible in consideration of the influence of the collapse of the contrast agent bubbles. This is the same in the normal B mode, but in any case, when the transmission sound pressure is lowered, the S / N ratio of the received signal is lowered. For example, the effect of staining the vascular system can be increased. On the other hand, it is often impossible to detect micro blood flow in the organ parenchyma.
[0010]
On the other hand, in the flash echo imaging method, the micro blood flow in the organ parenchyma can be instantaneously detected, but a transmission stop time for filling the tissue with the contrast agent is necessary, and the real-time property is impaired.
[0011]
The present invention has been made in view of the above circumstances, and automatically switches between a transmission mode using low sound pressure and a transmission mode using high sound pressure so that the advantages of both can be utilized, a display unit, and an image. An object of the present invention is to provide an ultrasonic diagnostic apparatus that includes a storage unit and can provide more convenient and effective information when an operator performs contrast echo.
[0012]
[Means for Solving the Problems]
In order to solve the above problems and achieve the object, the ultrasonic diagnostic apparatus of the present invention is configured as follows.
(1) The ultrasonic diagnostic apparatus of the present invention is an ultrasonic diagnostic apparatus that generates an ultrasonic diagnostic image by a contrast echo method performed by administering an ultrasonic contrast agent to a subject. Transmitting / receiving means for transmitting an ultrasonic wave under a first transmission condition suitable for sustaining, or under a second transmission condition suitable for collapsing the ultrasonic contrast agent, and receiving a reflected signal from a subject; The first diagnostic image obtained by the ultrasonic transmission based on the first transmission condition and the second diagnostic image obtained by the ultrasonic transmission based on the second transmission condition are divided into one screen and simultaneously and display means for displaying the first diagnostic image, the updated during ultrasonic transmission based on the first and second transmission conditions, before Symbol second diagnostic image, the first transmission condition Based on ultrasonic transmission Comprising a display control means for performing the display control of the screen so as not to be updated, the.
[0014]
According to such a configuration, the image group based on the first transmission condition (monitor transmission) suitable for maintaining the existence lifetime of the ultrasound contrast agent, and the second suitable for collapsing the ultrasound contrast agent. The image group based on the transmission condition (flash transmission) can be displayed simultaneously by dividing one screen by the display means.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention can be applied to all regions of interest (ROI) when a contrast medium is administered and the blood flow state is observed according to the degree of staining. In this embodiment, staining with a contrast medium flowing into the liver parenchyma or heart muscle is used. The case where the abnormal part is identified by grasping the blood flow dynamics from the shadow degree will be described.
[0016]
<Adaptive transmission power control method>
FIG. 1 is a block diagram showing a schematic configuration of an ultrasonic diagnostic apparatus according to an embodiment of the present invention. The ultrasonic diagnostic apparatus according to the present embodiment includes an ultrasonic probe 1 responsible for transmission / reception of an ultrasonic signal to / from a subject, and an apparatus that drives the ultrasonic probe 1 and processes a reception signal from the ultrasonic probe 1. A main body 20 and an operation panel 9 connected to the apparatus main body 20 and capable of inputting instruction information from the operator to the apparatus main body 20 are provided. The operation panel 9 is configured by connecting or installing a trackball 10A and a keyboard 10B for setting ROI.
[0017]
The apparatus body 20 includes an ultrasonic transmission unit 2, an ultrasonic reception unit 3, a receiver unit 4, a B-mode DSC unit 5, a memory synthesis unit 6, a display unit 7, an image memory 8, an FEI control circuit 13, and a memory control circuit 14. It comprises. Further, an ECG (electrocardiograph) 11 is connected to the ultrasonic diagnostic apparatus of the present embodiment, and the apparatus main body 20 includes a heartbeat detection unit 12.
[0018]
The ultrasonic transmission unit 2 includes a delay circuit and a pulser, and generates pulsed ultrasonic waves for scanning. Usually, the time interval of this scan is performed at a constant pulse repetition frequency (PRF). Further, the ultrasonic transmission unit 2 also receives control from the FEI control circuit 13 which is one of the main parts of this embodiment. Thereby, switching between high sound pressure transmission and low sound pressure transmission is performed. Details of the function of the FEI control circuit 13 will be described later.
[0019]
The reflected wave reflected by the discontinuous surface of the acoustic impedance in the subject is received by the ultrasonic probe 1. The echo signal output from the probe 1 for each channel is taken into the ultrasonic receiver 3. Here, the echo signal is amplified by a preamplifier for each channel, given a delay time necessary for determining the reception directivity by the reception delay circuit, and added by an adder. By this addition, the reflection component from the direction corresponding to the reception directivity is emphasized. As described above, the transmission directivity and the reception directivity are given to form a comprehensive ultrasonic beam in transmission and reception.
[0020]
Next, the configuration after the receiver unit 4 will be described. The receiver unit 4 includes a logarithmic amplifier (not shown), an envelope detection circuit, and an analog / digital converter (A / D converter). When the harmonic imaging method is applied, a band pass filter or the like is added to the receiver unit 4. As a result, the fundamental wave component of the transmission frequency is removed, and only the signal including the harmonic component can be passed.
[0021]
The output from the receiver unit 4 is converted from a raster signal sequence of an ultrasonic scan into a raster signal sequence of a video format by a B-mode DSC (digital scan converter) unit 5 and sent to a memory synthesis unit 6. The memory synthesis unit 6 arranges or superimposes information such as an image and setting parameters, and outputs the video signal to the display unit 7. Thus, a tomographic image representing the subject tissue shape is displayed.
[0022]
The image memory 8 includes a memory for storing and holding signals of the B-mode DSC unit 5 (one or both of an ultrasonic scan raster signal sequence and a video format raster signal sequence). This information can be called and used by an operator after diagnosis, for example, and in this case, can be output to the display unit 7 via the DSC unit 5 and the memory synthesis unit 6.
[0023]
The ECG 11 is used to obtain an electrocardiographic waveform mainly by attaching to the body surface of the subject. The heartbeat detection unit 12 sends the obtained electrocardiographic waveform to the memory synthesis unit 6 for display on the display unit 7 together with the ultrasonic image. The electrocardiographic waveform is output to the FEI control circuit 13 as a trigger signal for obtaining a heart image collected in synchronism with the electrocardiographic waveform, that is, a so-called electrocardiographic synchronized image.
[0024]
<Function of transmission condition control unit>
Next, specific configurations and operations of the FEI control circuit 13 and the memory control circuit 14 according to the main part of the present invention will be described.
[0025]
First, as described above, the FEI control circuit 13 performs transmission condition switching control in the ultrasonic transmission unit 2. That is, “a first transmission condition for transmitting an ultrasonic wave suitable for maintaining the lifetime of the ultrasonic contrast agent” and “a second ultrasonic wave for transmitting an ultrasonic wave suitable for collapsing the ultrasonic contrast agent” Switching control to “transmission condition” is performed. Hereinafter, transmission according to the first transmission condition is referred to as “monitor transmission”, and transmission according to the second transmission condition is referred to as “flash transmission”.
[0026]
The conditions necessary for alternately switching between monitor transmission and flash transmission are sent to the FEI control circuit 13 by the operator using the operation panel 9. Here, the most basic information is the transmission time interval of each of monitor transmission and flash transmission. A specific example will be described with reference to FIG.
[0027]
FIG. 2 is a diagram showing transmission timings of monitor transmission and flash transmission.
The values of the monitor transmission time interval T-moni and the number of transmission frames N-flash for flash transmission shown in the figure are input by the operator.
[0028]
Here, since flash transmission is a technique that attempts to enhance brightness by collapsing microbubbles, if this is done at very short intervals, the effect will be reduced, but on the other hand, bubbles will collapse instantly by flash transmission. End up. Based on this, the monitor transmission time interval is set. That is, the unit is specified in units of 1, 2,... [Seconds] or in units of 1, 2,. Also, the time interval of flash transmission is specified in units such as 1, 2,... [Number of frames]. Of course, the time may be specified as 0.05 seconds instead of the number of frames.
[0029]
In this embodiment, it is assumed that T-moni is set to 3 seconds and N-flash is specified to be two.
In accordance with this instruction, the ultrasonic transmission unit 2 performs monitor transmission only for 3 seconds, and the received signals are collected via the ultrasonic reception unit 3. Thereafter, the ultrasonic transmission unit 2 performs flash transmission, and reception signals for two frames are collected via the ultrasonic reception unit 3. And it returns to monitor transmission again, and the above operation | movement is repeated (refer FIG. 2). The transmission conditions are switched automatically by the FEI control circuit 13, but may be manually performed by an operator pressing a button or the like. An explanation of the above operation is described in the above-mentioned Japanese Patent Application No. 7-89443 (filed on April 14, 1995).
[0030]
By the way, although two types of transmission conditions can be switched, three or more types of transmission conditions may be switched for the purpose of efficiently obtaining a flash signal. For example, a transmission condition of “stop” for a relatively short time may be provided between the monitor transmission and the flash transmission. When a weak contrast agent that can be disintegrated by monitor transmission is used, the contrast agent flows into the tissue in the region of interest without being broken during transmission stop, and the flash signal is enhanced in the subsequent flash transmission. be able to.
[0031]
If the time for stopping the transmission is made longer, the intensity of the flash signal naturally increases. However, if the stop time is long, the original real-time property of the monitor scan is impaired, so it is considered that a fraction of a second to a few seconds is appropriate.
[0032]
The memory control circuit 14 receives information from the FEI control circuit 13 as to whether the current transmission is a monitor transmission or a flash transmission, and controls the B-mode DSC unit 5 and the memory synthesis unit 6 as follows. Do.
[0033]
First, control of the B mode DSC unit 5 by the memory control circuit 14 will be described. The memory control circuit 14 sends to the B-mode DSC unit 5 a control signal for making it possible to identify whether the image currently recorded in the image memory 8 is a monitor transmission or a flash transmission. As a result, the image group by monitor transmission and the image group by flash transmission are separated and stored in the image memory 8. Therefore, the following advantages can be obtained when the operator calls and reproduces an image from the image memory 8. That is, when an image is displayed on the display unit 7, it is possible to display whether the image is transmitted by monitor transmission or the image transmitted by flash transmission, so that both can be easily identified. Further, only an image group by flash transmission (or monitor transmission), for example, can be displayed by an instruction from the operator. The image group by flash transmission is useful for detecting and diagnosing the micro blood flow in the tissue with high sensitivity as the main purpose of the flash echo imaging method. On the other hand, an image group obtained by monitor transmission is useful for dynamic diagnosis by reproducing a moving image, for example, in the case of diagnosis of the heart.
[0034]
Since images by monitor transmission are obtained by continuous transmission, the total ultrasonic irradiation time also increases, and the number of images inevitably increases. In addition, an image obtained by monitor transmission may be used for specific purposes other than diagnosis, for example, for alignment for obtaining a flash echo. Therefore, there is a case where it is not necessary to record all the images transmitted by the monitor in the image memory 8. On the other hand, in flash transmission, confirmation by reproduction of the image memory 8 is necessary in order to capture an instantaneous flash image.
[0035]
Based on the above, the following modifications can be considered.
(Modification 1) The storage area of the image memory 8 is divided into a monitor area and a flash area in advance (either physical or software is acceptable), and the storage location is allocated under the control of the memory control circuit 14. Thereby, as shown in FIG. 3, the flash image group with a small number of sheets is not overwritten by the monitor image group.
(Modification 2) The image memory 8 is preliminarily dedicated to flash, and the memory control unit 14 performs control so as not to record an image by monitor transmission.
[0036]
Next, control of the memory composition unit 6 by the memory control circuit 14 will be described.
First, the reason for performing two or more flash transmissions (described above) will be described. According to the definition of flash transmission, it is a method of capturing an echo when the contrast agent is instantaneously disintegrated. When flash transmission is performed, a high-luminance image can be obtained in the first frame. On the other hand, it can be considered that the luminance due to the contrast agent has disappeared in the second and subsequent frames. Images after the second frame are used as follows. That is, the second frame and thereafter (at least one of them) is compared with the first frame to be used for confirming the disappearance site. This is important in that frames (images) with the same transmission condition are compared. Note that an image by flash transmission cannot be compared with an image by monitor transmission. In addition, the lost portion can be extracted by creating an image of the luminance difference between the second frame and the subsequent frames (at least one of them) and the first frame.
[0037]
Thus, it is important to perform a plurality of flash transmissions and record a plurality of images obtained thereby in the image memory 8. However, during observation of the diagnostic part, the dyed part can be known more clearly during the examination by displaying the first frame (image) having the highest luminance. Therefore, the memory control unit 14 notifies the memory synthesis unit 6 whether or not it is the first frame of flash transmission, and in response to this, the display unit 7 displays only the first frame. The frame and the subsequent frames are not displayed (see FIG. 4).
[0038]
Such display control is effective in single-screen display, but is more effective in two-screen display (dual display) described below.
FIG. 5 is a diagram schematically illustrating an example of two-screen display (dual display) by the display unit 7. As shown in the figure, by displaying an image by monitor transmission on one side and an image by flash transmission on the other side, the operator can observe the moving image in real time on the monitor image, while easily observing the image by flash transmission. It becomes possible to do.
[0039]
With respect to correspondence between transmission condition switching and image display, several modified examples will be described with reference to FIG. Also in this example, it is assumed that flash transmission is performed twice at regular intervals.
[0040]
FIG. 6A shows an example in which a monitor transmission image and a flash transmission image are sorted and displayed on each screen. Until the next image is obtained, the previous image is held on the screen. The flash screen (screen 2) may display all images transmitted by flash transmission. However, as described above, only the first image immediately after each flash transmission can be selectively displayed. Desirably, this example illustrates this case. Note that only the flash image is stored in the image memory.
[0041]
FIG. 6B shows an example in which all images sequentially obtained in the apparatus including the image of flash transmission are displayed as they are on the monitor screen (screen 1). Since an actual flash image is several frames (several tenths of a second) in a few seconds, even if flash images are instantaneously mixed in the monitor image, there is almost no problem in the observation of dynamics. On the other hand, the control of switching the display according to the identification of the transmission condition only needs to be performed for the flash screen, and the monitor screen only needs to display a continuous image, so that there is an advantage that signal control becomes relatively simple.
[0042]
Although FIG. 6 shows a division form in which the screen is divided into two equal parts, the image by the monitor transmission and the image by the flash transmission are respectively displayed on display screens having different sizes as shown in FIG. For example, it may be displayed in various divided forms.
[0043]
By the way, in this embodiment, the transmission sound pressure is changed when switching between monitor transmission and flash transmission. This can be realized, for example, by controlling specific parameters such as transmission drive voltage, drive frequency, wave number, waveform, or number of transmission drive elements (number of apertures) of the ultrasonic probe 1. Any parameter may be used as long as the sound field sound pressure at the diagnostic site or the fragility of the contrast agent bubbles can be changed as a result.
[0044]
Further, the reception condition may be changed between the monitor transmission and the flash transmission. For example, in the dual display example described above, harmonic imaging is generated at the time of flash transmission due to the disappearance of bubbles, so that harmonic imaging is used, and normal B-mode imaging is used during monitor transmission. As a result, penetration deterioration due to low sound pressure can be compensated, and since the tissue shape can be easily observed, alignment can be performed appropriately. More specifically, the reception conditions are switched as follows. That is, the FEI control circuit 13 sends a signal for distinguishing between monitor transmission and flash transmission to the receiver unit 4. Based on this signal, the receiver unit 4 performs processing related to harmonic imaging on the received signal at the time of flash transmission and processing related to B-mode imaging at the time of monitor transmission. More specifically, the receiver unit 4 changes the reception frequency or the reception band as the reception signal processing condition in accordance with the switching of the transmission condition.
[0045]
<Addition of time information>
The group of images recorded in the image memory 8 according to the present invention is composed of images collected at indefinite time intervals, as is apparent from the timing chart of FIG. Further, if flash transmission is manually performed several times, even if T-flash = 1, the interval becomes indefinite. For this reason, it is impossible to know at which time the image is an individual image.
[0046]
Therefore, the memory control unit 14 sends time information and information regarding the number of frames of flash transmission to the B-mode DSC unit 5, and adds these information to the image and records them in the image memory 8. Alternatively, a table for recording time information may be provided separately and written in association with the image.
[0047]
The time information is useful for creating a luminance change curve by calling an image recorded in the image memory 8. As a more specific application example, only the first frame of the flash image is extracted and a luminance change curve is created. Based on such time information, a luminance change curve in consideration of the time axis can be created for a flash image collected at an indefinite interval (or manually).
[0048]
Therefore, in diagnostic imaging related to contrast echo, which is performed by administering an ultrasound contrast agent to a subject, particularly flash echo imaging, the diagnostic performance is improved by the visualization of clearer micro blood flow, and accurate blood flow information is improved. Offer can be realized.
The present invention is not limited to the above-described embodiment, and can be implemented with various modifications.
[0049]
【The invention's effect】
As described above, according to the present invention, a transmission control system, a display unit, and an image storage unit that automatically switch between a transmission mode based on low sound pressure and a transmission mode based on high sound pressure and take advantage of both advantages. Therefore, it is possible to provide an ultrasonic diagnostic apparatus capable of providing more convenient and effective information when performing a contrast echo method performed by administering an ultrasonic contrast agent to a subject.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a schematic configuration of an ultrasonic diagnostic apparatus according to an embodiment of the present invention.
FIG. 2 is a view showing timings of monitor transmission and flash transmission according to the embodiment.
FIG. 3 is a view showing a control example of an image memory according to the embodiment.
FIG. 4 is a view showing image display timing according to the embodiment.
FIG. 5 is a diagram schematically illustrating an example of two-screen display in the display unit according to the embodiment.
FIG. 6 is a view showing a modification of image display according to the embodiment.
FIG. 7 is a diagram showing another example of a screen division mode in the display unit according to the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Ultrasonic probe 2 ... Ultrasonic transmission part 3 ... Ultrasonic reception part 4 ... Receiver part 5 ... B mode DSC part 6 ... Memory synthetic | combination part 7 ... Display part 8 ... Image memory 9 ... Operation panel 10A ... Trackball 10B ... Keyboard 11 ... ECG
12 ... Heart rate detector 14 ... Memory control circuit

Claims (1)

In an ultrasonic diagnostic apparatus for generating an ultrasonic diagnostic image by contrast echo method performed by administering an ultrasonic contrast agent to a subject,
An ultrasonic wave is transmitted under a first transmission condition suitable for maintaining the lifetime of the ultrasonic contrast agent or a second transmission condition suitable for disrupting the ultrasonic contrast agent, and from the subject. Transmitting and receiving means for receiving the reflected signal of
A first diagnostic image obtained by ultrasonic transmission based on the first transmission condition and a second diagnostic image obtained by ultrasonic transmission based on the second transmission condition are simultaneously displayed by dividing one screen. Display means to
The first diagnostic image is updated during ultrasonic transmission based on the first and second transmission conditions, and the second diagnostic image is updated during ultrasonic transmission based on the first transmission condition. Display control means for performing display control of the screen so as not to be updated,
An ultrasonic diagnostic apparatus comprising:

Images