JPH0779981A - Ultrasonic diagnostic apparatus - Google Patents

Abstract

PURPOSE:To enable to display clearly compositions of tissues and compositions of contrast medium in an examination by ultrasonic waves by subtracting images of scanning before prescription of a contrast medium from images of scanning after prescription of a contrast medium, which enables to create the image formed by compositions of the contrast medium included in signals received. CONSTITUTION:Before the contrast medium is prescribed to the subject, the intended section of the subject is scanned by ultrasonic beam from a probe 1 and the signals received is transmitted through the receiving system 3 to a B mode processing system 4, where the B mode image is created and made memorized in a frame memory 5. Subsequently, after the contrast medium is prescribed to the subject, the same section is scanned and B mode image created in the same way is supplied to subtractor of B mode image 6, which subtracts B mode image B in the frame memory 5 for each picture element. By this operation, only the composition of the contrast medium is extracted and by applying these processes to all picture elements, the image of the contrast medium can be created and their color information obtained by a convertor of color information 7 is made displayed on a monitor 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic diagnostic apparatus applied to diagnosis by an ultrasonic contrast agent.

[0002]

2. Description of the Related Art An ultrasonic diagnostic apparatus emits an ultrasonic pulse into a living body and receives a reflected wave reflected from a boundary surface of tissues having different specific acoustic impedances (the product of the density of both media and the sound velocity). After that, this is processed to obtain an image, which is a clinically useful device without exposure damage such as the X-ray diagnostic method. Moreover, real-time performance has improved due to the progress of various technologies typified by electronic scanning technology, and moving object measurement has become easier.

By the way, in recent years, development of ultrasonic contrast agents has progressed, and expectations for a detailed blood flow diagnosis comparable to X-ray angio are increasing. This contrast agent has the property of being different from the received signal from the living tissue in its intensity. As a result, the gradation level of the part where the contrast agent has flowed in differs from that of the other part on the B-mode image, so that the observer can observe how the contrast agent flows.

However, since the state of the flow of the contrast agent is distinguished from other tissue parts based on the difference in gradation level, an error may occur in the distinction. Also, the temporal change of the contrast agent is an important diagnostic material,
In the conventional device, there is no choice but to recognize the state of this variation from the moving image.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to address the above-mentioned circumstances, and an object thereof is to clearly separate a tissue component and a contrast agent component in ultrasonic diagnosis using a contrast agent. It is an object of the present invention to provide an ultrasonic diagnostic apparatus capable of displaying information.

[0006]

SUMMARY OF THE INVENTION The present invention is an ultrasonic diagnostic apparatus for generating an image using a received signal obtained by scanning an object with an ultrasonic beam, and an image obtained by scanning before administration of a contrast agent. Means for generating an image composed of the contrast agent component contained in the received signal by subtracting from the image scanned by the contrast agent and displaying the image composed of the contrast agent component together with the image scanned by the contrast agent before administration And means for doing so.

[0007]

According to the ultrasonic diagnostic apparatus of the present invention, the tissue component that does not change before and after the administration of the contrast agent is removed by subtracting the image obtained by the scanning before the administration of the contrast agent from the image obtained by the scanning after the administration of the contrast agent. By generating an image including the contrast agent component and displaying this together with the image obtained by scanning before administration of the contrast agent, the tissue component and the contrast agent component can be clearly separated and displayed.

[0008]

Embodiments of the ultrasonic diagnostic apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the first embodiment. The sector type electronic scanning type probe 1 is composed of a plurality of transducers arranged one-dimensionally. The probe 1 is not limited to the sector type electronic scanning type, and may be a linear type or a mechanical scanning type. A transmission system 2 is connected to the probe 1. The transmission system 2 supplies a drive pulse to each transducer of the probe 1. The transmission system 2 makes the output timings of the drive pulses different among the transducers, whereby the ultrasonic beam can be oscillated to scan an arbitrary cross section of the subject.

The reflected wave from the subject is received by the same oscillator as that at the time of transmission, and the received signal is supplied to the receiving system 3. The receiving system 3 gives each reception signal a delay time opposite to that at the time of transmission and adds them. A B-mode processing system 4 is connected to the output of the receiving system 3.

The B-mode processing system 4 logarithmically amplifies the output of the receiving system 3, detects the envelope, converts the detected signal into a digital signal, and outputs the digital signal. The B-mode image from the B-mode processing system 4 is supplied to the frame memory 5 and the subtractor 6. The frame memory 5 stores the B-mode image obtained by scanning before the administration of the contrast agent, and supplies the B-mode image as a mask image to the subtracter 6 and the digital scan converter (DSC) 8 after the administration of the contrast agent. The subtractor 6 subtracts the B-mode image obtained by scanning before the administration of the contrast agent from the B-mode image obtained by scanning after the administration of the contrast agent for each pixel, and an image composed of the contrast agent component included in the received signal (hereinafter referred to as “contrast agent image”). Is generated).

The contrast agent image is combined with the B-mode image by the digital scan converter 8 via the color information converter 7 before the contrast agent is scanned from the frame memory 5 and displayed on the monitor 9. Color information converter 7
Includes a color bar corresponding to gray scale, and the color bar is used to convert a contrast agent image into a color image. As this color bar, as shown in FIGS.
As shown in (c), either a type in which the hue changes, a type in which the brightness of a predetermined color (for example, green) changes, or a type in which the saturation of a predetermined color (for example, green) changes is adopted. In the following description, it is assumed that a color bar of a type whose hue changes is adopted.

Next, the operation of this embodiment will be described. Before the contrast agent is administered to the subject, the ultrasonic beam from the probe 1 scans the target cross section of the subject. This reception signal is sent to the B-mode processing system 4 via the reception system 3 and is generated in the B-mode image there. The B-mode image obtained by scanning before the administration of the contrast agent is stored in the frame memory 5. FIG. 4A shows an example of this B-mode image B.

After the contrast agent is administered to the subject, the ultrasonic beam from the probe 1 scans the same target section as before the administration of the subject. This reception signal is sent to the B-mode processing system 4 via the reception system 3 and is generated in the B-mode image there. FIG. 4B shows an example of this B-mode image Bm. B-mode image Bm by scanning after administration of this contrast agent
Is supplied to the subtractor 6. At this time, the B-mode image B obtained by scanning the frame memory 5 before administration of the contrast agent is also supplied to the subtractor 6.

B-mode image B by scanning after administration of contrast agent
In the subtractor 6, m is subtracted for each pixel of the B-mode image B obtained by scanning before administration of the contrast agent. FIG. 3 shows the luminance (pixel value) at one pixel after the time t0 when the contrast agent is administered.
3 is a graph showing changes with time.

The B-mode image Bm is generated at time tm after administration of the contrast agent. The brightness information of this pixel includes a tissue component and a contrast agent component. Among them, the tissue component does not change with time, but the contrast agent component changes with time according to the inflow of the contrast agent. Therefore, only the contrast agent component is extracted by subtracting the brightness of the corresponding pixel of the B-mode image B obtained by scanning before administration of the contrast agent, that is, the tissue component S0 from the brightness of each pixel. By performing this process individually for all pixels, the contrast agent image Gm shown in FIG. 4C is generated.

The contrast agent image Gm is sent to the color information converter 7 where it is converted into color information. This conversion is performed according to the color bar corresponding to gray scale as described above. That is, one of the hues that gradually changes from green to orange is assigned according to the magnitude of brightness.

This color image is supplied to the digital scan converter 8. The digital scan converter 8 is also supplied with a B-mode image B obtained by scanning the frame memory 5 before administration of the contrast agent. The digital scan converter 8 combines the color image and the B-mode image B. This synthesizing process is performed, for example, by giving luminance information at the same position in the B-mode image B to pixels in the color image that have no color information. Therefore, in this composite image, color information and luminance information are mixed in different pixels. The composite image and the B-mode image B are arranged in parallel in one display frame by the digital scan converter 8 and output to the monitor 9. An example of the display screen of the monitor 9 is shown in FIG. In this way, the portion into which the contrast agent has flowed is displayed in color, and the portion into which the contrast agent has not flowed in displays luminance information (tissue information), so that the anatomical position into which the contrast agent has flowed can be recognized. In addition, the brightness information of the part where the contrast agent that has become invisible due to the color display is
This can be confirmed in the B-mode image B displayed in parallel with this composite image.

In the above description, the B-mode image was explained, but it may be blood flow information (color flow mapping image). In this case, the B-mode processing system is replaced with the blood flow information processing system. You can deal with it. In addition, B
In principle, a mode image can be generated by repeating transmission / reception once per raster for a plurality of rasters, and therefore, it is not necessary to repeat transmission / reception multiple times per raster as in color flow mapping, which is excellent in real time. Especially, it is advantageous for observation of tissue perfusion. On the other hand, when blood flow information is handled instead of the B-mode image, the portion other than the color display of the contrast agent becomes the blood flow information, which is advantageous for blood vessel observation. Since the B-mode image and the blood flow information have different advantages in this way, it is desirable to use them properly.

Further, in the above description, the contrast agent component can be well extracted when the diagnosis target has few movements, for example, the abdomen, but when the patient is beating like the heart, the contrast agent component can be well extracted. There is a problem that it cannot be extracted. This problem can be easily solved by the heartbeat synchronization function. That is, before administration of a contrast agent, a plurality of B-mode images having different cardiac time phases are repeatedly scanned by referring to the output of the electrocardiograph shown in FIG. 6 at a plurality of different cardiac time phases t0 to tn of one heartbeat. The generated B-mode images having the same time phase as the B-mode image after the administration of the contrast agent are selectively used from the frame memory group and stored in the frame memory group.
Subtract from the mode image.

Next, a second embodiment will be described. Figure 7
FIG. 3 is a block diagram showing the configuration of this embodiment. 7, the same parts as those in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted.

In this embodiment, the threshold value setting device 10 is characteristically provided. The B-mode image from the B-mode processing system 4 before administration of the contrast agent is supplied to the threshold value setting device 10.
The threshold value setting device 10 sets a threshold value from the B-mode image and supplies it to the subtractor 6. The entire range of the B-mode image before administration of the contrast agent, or the maximum value Smax of the brightness value (pixel value) in the designated ROI (region of interest) is set as the threshold value. The subtractor 6 subtracts the threshold value Smax for each pixel from the B-mode image after administration of the contrast agent from the B-mode processing system 4 to extract a contrast agent component for each pixel and generate a contrast agent image. To do.

FIG. 8 is a graph showing the change over time in the luminance (pixel value) in one pixel other than the pixel showing the maximum value Smax after the time t0 after the administration of the contrast agent. By subtracting the maximum value Smax from this brightness value, the contrast agent component indicated by the diagonal lines is extracted.

As described above, according to this embodiment, the same effect as that of the first embodiment can be obtained, and the tissue component can be almost completely removed. In the present embodiment, an error is likely to occur due to the variation in power, but the power of the contrast medium is sufficiently larger than that of the tissue, so this error can be ignored. In the present embodiment as well, as in the first embodiment, blood flow information may be handled instead of the B-mode image, or a heartbeat synchronization function may be provided.

Next, a third embodiment will be described. Figure 9
FIG. 3 is a block diagram showing the configuration of this embodiment. 9, the same parts as those in FIG. 1 are designated by the same reference numerals and detailed description thereof will be omitted.

The output of the receiving system 3 is supplied to the blood flow information processing system 11 together with the B mode processing system 4. The B-mode image from the B-mode processing system 4 is supplied to the first input terminal of the switch 18 and the frame memory 5. The B-mode image obtained by scanning before administration of the contrast agent is stored in the frame memory 5. The output of the frame memory 5 is connected to the second input terminal of the switch 18. By switching the connection of the switch 18, the operator can selectively display the latest B-mode image and the B-mode image by scanning before administration of the contrast agent.

The blood flow information processing system 11 quadrature-phase-detects the output of the receiving system 4, obtains a Doppler shift signal by removing high frequency components from this detection result, and then obtains a Doppler shift signal from the Doppler shift signal. Unnecessary clutter components from slow-moving objects such as etc. are removed, and the signals from which these clutter components have been removed are subjected to real-time frequency analysis for each of the two-dimensional multipoints, and the average of 1 frame is used using this analysis result. Measure velocity information, its variance information, and power information.
Power information measuring unit 1 for measuring power information of one frame
Only 9 is shown, and other parts are omitted.

The power output from the power information measuring unit 19 is supplied to the subtractor 6 and the frame memory 12. The frame memory 12 stores power information of one frame by scanning before administration of a contrast agent. The power information of the frame memory 12 is supplied to the subtractor 6 as a mask image after administration of the contrast agent. The subtracter 6 subtracts, for each pixel, the power information of one frame from the frame memory 12 from the scan performed before the administration of the contrast agent from the power information of the one frame from the scan performed after the administration of the contrast agent.

The output of the subtractor 6 is supplied to the comparator 14 and the maximum value holding unit 16. In the comparator 14, the subtractor 6
The subtraction result of each pixel from is compared with the threshold value supplied from the threshold value setting unit 13, a plus signal is output when the subtraction result is larger than the threshold value, and the subtraction result is larger than the threshold value. When it is small, a minus signal is output for each pixel. This threshold value is set to a value having a signal level at least larger than that of the tissue signal. Therefore, when the positive signal is output from the comparator 14, it indicates that the contrast agent signal exists, and when the negative signal is output, it indicates that the contrast agent signal does not exist.

The output of the comparator 14 is the first time measuring device 15
And the maximum value holder 16 are supplied. The first time measuring device 15 outputs the time when the output from the comparator 14 is inverted from the minus signal to the plus signal, that is, the time when the contrast agent arrives (hereinafter referred to as “arrival time”), and the plus signal. Time, that is, the time required for the contrast medium to flow in and out (hereinafter referred to as "flow time")
Is measured for each pixel. Therefore, the first time measuring device 15
Has a built-in timer and starts this timer when a contrast agent is administered, and measures the arrival time and the flow time starting from the contrast agent administration time. The arrival time and the flow time measured by the first time measuring device 15 are supplied to the color information converter 7.

The maximum value holding device 16 detects, for each pixel, the maximum value of the output of the subtractor 6 during the period when the output from the comparator 14 is a plus signal. This maximum value is supplied to the color information converter 7 and the second time measuring device 17.

The second time measuring device 17 is a time when the output of the subtractor 6 reaches the maximum value from the time when the contrast agent is injected,
That is, the time when the inflow amount of the contrast agent becomes maximum (hereinafter referred to as “maximum inflow time”) is measured for each pixel. Therefore, the second time measuring device 17 has a built-in timer and starts the timer when the contrast agent is administered to measure the maximum inflow time. This maximum inflow time is the color information converter 7
Is supplied to.

The color information converter 7 is shown in FIG.
As shown in (b) and (c), a color bar corresponding to the time, a color bar corresponding to the time, and a color bar corresponding to the maximum value are provided, and various color images are generated using these color bars. This color bar is shown in Figure 2.
As shown in (a), (b) and (c), the type in which the hue changes, the type in which the luminance of a predetermined color (for example, green) changes, and the type in which the saturation of a predetermined color (for example, green) changes. Is adopted. The following description will be made assuming that a color bar of a type in which the hue changes is adopted.

Next, the operation of this embodiment will be described. Before the contrast agent is administered to the subject, the ultrasonic beam from the probe 1 scans the target cross section of the subject. The reception signal from the reception system 3 is sent to the B-mode processing system 4 via the reception system 3 and is generated in the B-mode image there. The B-mode image before administration of the contrast agent is stored in the frame memory 5. Further, the received signal from the receiving system 3 is also supplied to the blood flow information processing system 11, where it is generated as power information.
The power information before administration of the contrast agent is stored in the frame memory 12
Memorized in.

After the contrast agent is administered to the subject, the ultrasonic beam from the probe 1 repeatedly scans the same target section as before the administration of the subject to sequentially generate B-mode images. By switching the connection of the switch 18, the operator can display the B-mode images by scanning before the administration of the contrast agent in a frozen state, or can display the sequentially generated B-mode images in real time.

Further, the power information of one frame is sequentially generated by the power information measuring unit 19 of the blood flow information processing system 11 in accordance with the above repeated scanning. This power information is supplied to the subtractor 6. At this time, the power information of one frame obtained by scanning the frame memory 12 before administration of the contrast agent is also supplied to the subtractor 6.

The power information obtained by scanning after the administration of the contrast agent is
The subtractor 6 sequentially subtracts power information obtained by scanning before administration of the contrast agent for each pixel. FIG. 11 is a graph showing the change over time in the power of one pixel after the time t0 after administration of the contrast agent. The hatched portion in FIG. 11 is the component obtained as a result of the subtraction. The subtraction result of the subtractor 6 is supplied to the comparator 14 and the maximum value hold unit 16.

The comparator 14 compares the subtraction result of each pixel from the subtractor 6 with the threshold value Pth supplied from the threshold value setting unit 13, and when the subtraction result is larger than the threshold value Pth, it is positive. A signal is output, and when the subtraction result is smaller than the threshold value Pth, a minus signal is output for each pixel.

The output of the comparator 14 is sequentially supplied to the first time measuring device 15 and the maximum value holding device 16. In the first time measuring device 15, the built-in timer is started when the contrast agent is administered, and the arrival time corresponding to the output from the comparator 14 being inverted from the negative signal to the positive signal, the time t in FIG.
1 is measured for each pixel. Further, in the first time measuring device 15, the time at which the output from the comparator 14 re-inverts from the plus signal to the minus signal, in FIG. 11, the time t3 is measured,
The time from time t1 to time t3, that is, the flow time is measured for each pixel. The arrival time and the flow time are supplied to the color information converter 7.

In the maximum value holding device 16, the maximum value Pmax of the subtraction result of each pixel output from the subtractor 6 is detected for each pixel while the output of the comparator 14 is a plus signal. This maximum value is calculated by the color information converter 7 and the second time measuring device 17
Is supplied to.

In the second time measuring device 17, the built-in timer is started when the contrast agent is administered, and the maximum inflow time when the maximum value is detected by the maximum value holding device 16, the time t4 in FIG. 11 is for each pixel. To be measured. This maximum inflow time is supplied to the color information converter 7.

With the above operation, the color information converter 7 is
An arrival time distribution image, a flow time distribution image, a maximum value distribution image, and a maximum inflow time distribution image having pixel values of arrival time, flow time, maximum value, and maximum inflow time parameters are supplied. A desired image is designated by the operator. In the color information converter 7, each pixel value of the designated image is converted into corresponding color information according to the color bar.

This color image is supplied to the digital scan converter 8. Further, the digital scan converter 8 is supplied with a B-mode image obtained by scanning the frame memory 5 before administration of a contrast agent or a real-time B-mode image from the B-mode processing system 4. The digital scan converter 8 combines the color image and the B-mode image. This synthesizing process is performed by giving luminance information at the same position in the B-mode image to the pixels having no color information in the color image, as in the first embodiment. This combined image is arranged in parallel with the B-mode image in one display frame by the digital scan converter 8 and output to the monitor 9 for display.

As described above, in this embodiment, the arrival time distribution image, the flow time distribution image, the maximum value distribution image, and the maximum inflow time distribution image can be displayed together with the B-mode image.
As a result, the temporal situation of the contrast agent flowing in each position is provided as a still image, and therefore, it becomes possible to clearly understand the potential information included in the moving image. In addition, since these four types of images have a larger amount of information than a moving image, there is a secondary effect that it is not necessary to record a moving image that requires a huge storage capacity.

In the above description, blood flow information (color flow mapping image) has been described, but it goes without saying that it may be a B mode image. Further, the heartbeat synchronization function may be used to reduce the movement error.

Next, a fourth embodiment will be described. Figure 1
2 is a block diagram showing the configuration of the present embodiment. 12, the same parts as those in FIGS. 1, 7, and 9 are designated by the same reference numerals, and detailed description thereof will be omitted.

In this embodiment, as in the second embodiment, the threshold value setting device 10 is characteristically provided. The blood flow information before the administration of the contrast agent from the power information measuring unit 19 of the blood flow information processing system 11 is supplied to the threshold value setting unit 10, where all the pixels or the ROI (region of interest) designated. The maximum value of the brightness value (pixel value) of the pixel or the maximum value of the brightness value of each pixel that changes with time is set as the threshold value. The subtracter 6 removes the tissue component for each pixel by subtracting this threshold value from each pixel value of the blood flow information after the contrast agent administration from the power information measuring unit 19. The processing after this subtraction is the same as in the third embodiment.

Also in this embodiment, the same effect as that of the third embodiment can be obtained, and blood cells and tissue components can be almost completely removed. In the present embodiment, an error is likely to occur due to the variation in power, but the power of the contrast medium is sufficiently larger than that of the tissue, so this error can be ignored. In this embodiment, the blood flow information has been described, but it goes without saying that it may be a B mode image.
Further, the heartbeat synchronization function may be used to reduce the movement error. Of course, the present invention is not limited to the above-described embodiments, but can be variously modified and implemented.

[0048]

INDUSTRIAL APPLICABILITY The present invention removes a tissue component that does not change before and after the administration of the contrast agent by subtracting the image obtained by the scanning before the administration of the contrast agent from the image obtained by the scanning after the administration of the contrast agent. It is possible to provide an ultrasonic diagnostic apparatus capable of clearly separating and displaying a tissue component and a contrast agent component by generating an image consisting of and displaying this together with an image obtained by scanning before administration of the contrast agent.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of an ultrasonic diagnostic apparatus according to the present invention.

FIG. 2 is a diagram showing an example of a color bar included in the color information converter of FIG.

FIG. 3 is a diagram showing a temporal change in luminance (pixel value) of one pixel after administration of a contrast agent.

FIG. 4 is a diagram showing an example of a B-mode image, a contrast agent image, and a composite image thereof.

5 is a diagram showing an example of a display screen of the monitor of FIG.

FIG. 6 is a diagram showing an electrocardiographic waveform.

FIG. 7 is a block diagram showing the configuration of a second embodiment.

FIG. 8 is a diagram showing changes over time in the brightness (pixel value) of one pixel after administration of a contrast agent.

FIG. 9 is a block diagram showing the configuration of a third embodiment.

10 is a diagram showing an example of a color bar included in the color information converter of FIG.

FIG. 11 is a diagram for explaining various kinds of information obtained by the third embodiment.

FIG. 12 is a block diagram showing the configuration of a fourth embodiment.

[Explanation of symbols]

1 ... Probe, 2 ... Transmission system, 3 ... Reception system, 4 ... B mode processing system, 5 ... Frame memory, 6 ... Subtractor 7 ... Color information converter, 8 ... Digital scan converter, 9 ... Monitor.

Claims (4)

[Claims] 1. An ultrasonic diagnostic apparatus for generating an image using a received signal obtained by scanning a subject with an ultrasonic beam, wherein an image obtained by scanning before administration of a contrast agent is an image obtained by scanning after administration of a contrast agent. And means for generating an image composed of the contrast agent component contained in the received signal by subtracting from the image, and means for displaying the image composed of the contrast agent component together with the image obtained by scanning before administration of the contrast agent. Characteristic ultrasonic diagnostic equipment. 2. An ultrasonic diagnostic apparatus for generating an image using a received signal obtained by scanning an object with an ultrasonic beam, the maximum value among all pixel values of the image obtained by scanning before contrast agent administration. Means for generating an image composed of a contrast agent component included in the received signal by subtracting from the pixel value of each image obtained by scanning after the administration of the contrast agent; An ultrasonic diagnostic apparatus comprising: means for displaying together with an image by scanning. 3. An ultrasonic diagnostic apparatus for generating an image using a received signal obtained by scanning a subject with an ultrasonic beam, wherein an image obtained by scanning before administration of a contrast agent is an image obtained by scanning after administration of a contrast agent. From the subtraction means, a means for measuring the change over time of the subtraction result of the subtraction means for each pixel, and generating an image corresponding to this change, the image generated by the generation means before the contrast agent administration. And a unit for displaying the image together with the scanned image. 4. An ultrasonic diagnostic apparatus for generating an image using a reception signal obtained by scanning an object with an ultrasonic beam, wherein the maximum value among all pixel values of the image obtained by scanning before administration of a contrast agent is used. Means for subtracting from each pixel value of the image by scanning after contrast agent administration, means for measuring the change over time of the subtraction result of the subtraction means for each pixel, and generating an image according to this change, An ultrasonic diagnostic apparatus comprising: a unit configured to display the image generated by the generating unit together with the image obtained by scanning before administration of the contrast agent.