JPH0429380B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a radiation diagnostic apparatus that obtains and displays image information useful for medical diagnosis by detecting radiation transmitted through a subject.

[Technical background of the invention]

Conventionally, U.S. Pat.
A technique as shown in No. 4204226 is disclosed.

In these methods, an X-ray image of the circulatory system before contrast agent injection is used as a mask image, and a difference image is obtained from this X-ray image after contrast agent injection to obtain an image of the target circulatory system portion.

However, inter-image calculations included in the process of creating contrast-enhanced diagnostic images in these devices, such as sum or difference calculations between pre-contrast images, sum or difference calculations between images during contrast-enhancement, and sum or difference calculations between pre-contrast and intermediate images. Difference calculations and the like are performed while ignoring the pulsations that the circulatory system always has. Therefore, a false image caused by a heartbeat phase shift, which is particularly noticeable in the heart region, is generated in the diagnostic image. Second, since the sum calculation for improving the concentration resolution actually takes the sum of images with different heartbeat phases, a diagnostic image with a low spatial resolution can be generated. In other words, it has the disadvantage that it results in a significant deterioration in diagnosis.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and is intended to enable more accurate diagnosis by suppressing the occurrence of false images or blurring caused by heartbeat phase shifts, that is, the decrease in spatial resolution. The purpose of the present invention is to provide a radiological diagnostic device that has the following features.

[Summary of the invention]

That is, in order to achieve the above object, the present invention injects a contrast agent into the circulatory system of a subject, generates radiation with a radiation generator, and detects the radiation transmitted through the subject, thereby obtaining a radiographic image of the subject. Obtain a signal, digitally convert it into image data, and store this image data in a storage means, thereby collecting and storing a pre-contrast image and an image during contrast for at least one heartbeat. In a device that performs calculations on the collected image data and extracts images of areas with density changes from images before contrast medium injection to images during contrast medium injection for diagnosis, the heartbeat phase is determined from the collected image data. By knowing this, selecting images with the same heartbeat phase from among the stored images, and extracting the changing parts between the images with the same heartbeat phase, an image of only the contrast-enhanced cardiovascular blood vessels for one heartbeat is created. processing means, which collects and stores circulatory system radiographic images of the subject for at least one heartbeat before contrast imaging and one heartbeat during contrast imaging, and calculates the time of concentration within the region of interest in the stored images. By determining the change, correlating the concentration time change with the heartbeat phase, selecting images with the same heartbeat phase from among the above-mentioned stored images, and extracting the changing portions between the images with the same heartbeat phase. , which obtains a phase-specific diagnostic image for one heartbeat, and creates an unblurred image of only the circulatory system when diagnosing the circulatory system, which involves periodic changes.

The present invention also provides an image collection storage means for collecting and storing circulatory system radiographic images for at least two heartbeats of a subject, and a concentration time change creation means for calculating a time change in concentration within a region of interest in the stored image. , by knowing the images with the same heartbeat phase among the stored images from the concentration time change, and extracting the changing parts between the images with the same heartbeat phase, 1.
using an image processing means to obtain a diagnostic image of the heartbeat,
The temporal change in concentration within the region of interest is determined from the above-mentioned circulatory system radiographic images for at least two heartbeats, and from this, the images with the same heartbeat phase among the above-mentioned stored images are determined, and the changing portion between the images with the same heartbeat phase is determined. By extracting each of these, it is possible to obtain a diagnostic image of the difference for each phase for one heartbeat, thereby making it possible to obtain an image of the difference without blur caused by the heartbeat.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of this device. In the figure, 1 is an X-ray generator that irradiates X-rays to the subject 2, and 3 is an X-ray generator that irradiates the subject 2 with X-rays.
This is an image acquisition device provided opposite to the line generator 1. This image acquisition device 3 is a device that converts an X-ray transmitted image obtained by passing through the subject 2 into an analog electrical signal, and is, for example, an image intensifier (hereinafter referred to as II) that converts an X-ray image to an optical image.
X-ray detection consists of an optical system that guides the optical image outputted by this II, an image pickup tube that captures the optical image guided by this optical system, and an image pickup tube control device that controls this image pickup tube. It consists of a device and an A/D converter that converts the analog signal output from the X-ray detection device into a digital signal and outputs it, and captures the optical image obtained by converting the X-ray transmission image with II. An analog signal obtained by imaging with a tube, that is, an image signal of an X-ray transmission image, is converted into digital data by an A/D converter, which is then logarithmically converted by a logarithmic converter and output.

4 is an image processing device, and the image collecting device 3
It receives an X-ray transmission image sent in the form of data from , saves it for each frame, calculates the image of each frame against the saved pre-contrast image, and calculates the density changes for a predetermined region of interest. This is a device that obtains a part as an image. This image processing device 4 includes an image storage unit (for example, a frame memory) that can store collected images and processed images output from the image collection device 3 in units of frames, and a A concentration time change means for creating a time change diagram of concentration for a predetermined region of interest; a heartbeat cycle detection means for detecting the heartbeat cycle and phase of each stored image; and a time filter processing section that performs a sum calculation with a weighting coefficient to create a diagnostic image for one heartbeat cycle.

5 is an image display device, and the image processing device 4
It displays a processed image given in the form of image data. The image display device 5 includes a D/A converter that converts data from the image processing device 4 into an analog signal, and a display that displays the analog signal as an image.

6 is a system controller that controls the entire device, and includes a central processing unit.

Reference numeral 7 denotes a system console, which has selection keys for selecting imaging conditions, image processing modes, sequences, etc. according to the target region within the subject 2, which are preprogrammed in the system controller 6. This is for setting conditions etc.

Reference numeral 8 denotes an X-ray generation controller, which is a device that, under the control of the system controller 6, controls the X-ray generator 1 to generate X-rays under the exposure conditions set by the system console 7.

Reference numeral 9 denotes a contrast agent injection device for injecting a vascular contrast agent into the subject 2, which injects a predetermined amount of vascular contrast agent at a predetermined time under the control of the system controller 6.

Next, the image processing device 4 will be explained.

As shown in FIG. 2, the image processing device 4 includes an image processing controller 20, a concentration time change diagram creating means 21, a heartbeat cycle detecting means 22, a time filter processing means 23, a function measuring means 24, and an unprocessed image. an image storage unit 25 that stores the processed image and the like;
It has a selector 26. Among these, the image processing controller 20 is configured to receive the control signal C ₁ output from the system controller 6 and output a control signal that controls the operation sequence of each part in the image processing device 4. . In addition, the image processing controller 20 particularly receives information such as the period and phase of the heartbeat of the subject 2 detected from the heartbeat period detection means 22 via the control line u, and
The image processing controller 20 passes the control line _P3 to the time filter processing means 23, the control line _P4 to the function measurement means 23, and the control lines _Q1 to _QN to the image storage unit 25. Each control signal is output to the selector 25 via a control line R. The concentration time change chart creation means 21 collects collected image data transmitted from the image collecting device 3 via a data bus DB1 for image data transmission, or collected image data transmitted from an image storage section 25 (described later) via a data bus DB3 or DB4. Upon receiving the incoming image data, the system controller 6 measures the temporal change in density value (image number) within the region of interest determined in advance, and stores the image data in the image storage unit 2.
Store in 5.

The heartbeat detection means 22 receives the concentration time change diagram obtained by the concentration time change diagram creation means 21, calculates the times (image numbers) indicating the maximum and minimum values of concentration in the diagram, and The period and period change of the heartbeat are detected, and the correspondence between the image number and the heartbeat change is transmitted to the image processing controller 20 via the control line u.

The image storage section 25 has a frame memory for N frames, and in response to the frame control outputs Q ₁ to Q _N of the image processing controller 20, a desired frame memory is selected from among the N frames, and the selected frame memory is selected. The data bus
The image data provided via the DB 2 is sequentially stored in addresses designated by the image processing controller 20, and the image data is also stored in the image processing controller 20.
Under the control of , the image data is read from the specified address of the selected frame memory,
Output to data buses DB3 and DB4.

As shown in FIG.
It is composed of. Image processing controller 2
0 controls the multiplication of the filter coefficients G ₁ and G ₂ in the multipliers 231 and 232 of the time filter processing means 23 via the control line P ₃ . data bus DB
The image data input through G 3 is input to a multiplier 231 , multiplied by a weighting coefficient G ₁ , and the result is output to an adder 233 . On the other hand, data bus DB4
The image data input via the multiplier 232 is input to the multiplier 232, multiplied by the filter coefficient _G2 , and the result is output to the adder 233. Further, the adder 233 calculates the sum of the input image data from the two multipliers 231 and 232, and outputs the result to the image storage section 25 via the data bus DB2. The function measuring means 24 is controlled by the image processing controller 20 and is connected to the data bus DB3 or
Image data is input via DB4, functions such as heart contour, heart volume, dimension, etc. are measured, and the results are output to data bus DB2 as images or measurement diagrams. The selector 26 connects the data bus DB3 and
The image data of DB4 is input, and one system of data is selected by the control signal R output from the image processing controller 20 and transferred to the data bus.
This is a changeover switch for outputting to the above-mentioned image display device 5 via the DB 5.

Next, the operation of the present apparatus having the above-mentioned configuration will be explained by taking as an example a case in which a contrast cardiac image using a contrast agent is displayed.

First, a procedure for collecting an image before contrast agent injection (pre-contrast image) and an image after the start of contrast agent injection (image during contrast), which will serve as a mask image, will be explained.

The system console 7 is provided with a routine key for collecting and storing images before and during contrast imaging. Therefore, operate this key. A program is set in advance in the system controller 6 so that by operating this key, the system controller 6 displays a list of standard X-ray exposure conditions and timing corresponding to the imaging site and contrast agent injection site on the display section of the system console 7. Therefore, by operating the above keys, the system controller 6 displays on the system console 7 a list of standard X-ray exposure conditions and timing corresponding to the imaging site and contrast agent injection site, and selects the diagnostic target site and contrast agent injection site. Request input of injection site, etc. In response to this, the operator specifies the heart as the diagnostic target site and the brachiocephalic vein as the contrast medium injection site.
When standard mode collection is specified from the system console 7, the system controller 6
A setting command for radiation exposure conditions is sent to the X-ray generation controller 8 to set parameters, the contrast agent injection device 9 is put on standby, the image acquisition device 3 is set to standard acquisition conditions, and the image processing device 4 and image display are set. The device 5 is placed on standby. Next, when the operator operates the collection start key on the system console 7, the system console 7 outputs a collection start signal. Then, the system controller 6 drives the contrast agent injection device 9 to inject the contrast agent into the subject 2 at the timing described above, and then drives the X-ray generation controller 8 to perform the above settings from the X-ray generator 1. X
Expose the line. At this point, the contrast agent has not yet reached the heart, so the X-rays will pass through the subject 2 at the imaging site before contrast. The X-rays that have passed through the subject 2 are detected by the image acquisition device 3, converted into electrical signals, A/D converted, and converted into digital data. and. Further, the data is logarithmically transformed, and then this data is input to the image processing device 4 via the data bus DB1. The input image data is input to the concentration time change chart creation means in the image processing device 4, the concentration within a predetermined region of interest is measured, and the input images are sequentially sent to the selected image storage section 25 via the data bus DB2. The data is then stored at an address corresponding to the pixel position of the image in the frame memory.

Also, this stored data is stored on data bus DB3 and
It is also sent to the image display device 5 via the DB 5, where the collected image is displayed.

X-rays are sequentially emitted in pulses at predetermined timing, and data as described above is collected each time the X-rays are emitted. Therefore, as the contrast agent reaches the heart, the concentration of the contrast agent portion of the collected image becomes progressively higher. Image data collected for each X-ray exposure is stored in different frame memories. Since the collected images are displayed on the image display device 5, the state of the collected images can be observed.

In this way, images are collected according to the X-ray exposure sequence.

Along with this image collection, the density time change chart creation means 21 uses the image data sent from the image signal collection device 3 via the data bus DB1 and the image data sent from the image storage section 25 via the data bus DB3 or DB4. Upon receiving the image data of the previous frame, the time change of the density value of the image data within the region of interest determined in advance by the system controller 6 is measured and stored in the frame memory for storing the density time change diagram of the image storage unit 25. .

When the X-ray exposure sequence is completed and the X-rays are stopped, the time-varying graph of the concentration of the region of interest that has been obtained so far is read out from the image storage unit 25 and provided to the image display device 5 for display.

This time change diagram is also input to the heartbeat detecting means 22 at the same time. Here, the maximum and minimum values of concentration are sequentially determined in the concentration time change chart data, and the heartbeat cycle and phase are determined. and,
These are classified by heartbeat number, and the periodic changes in heartbeat and density value information are transmitted to the image processing controller 20 through the control line u. Then, the image processing controller 20 inputs the periodic change information and concentration value information of the heartbeat output from the heartbeat detection means 22, and sends the filter count to the time filter processing means 22.
G ₁ , G _2, etc. are counted and input, and data are input to the image storage unit 25 via the data bus DB3 or DB4.
A control signal is sent to sequentially output images corresponding to image signals having the same heartbeat phase. Time filter processing was performed between images having the same heartbeat phase, and the images were sequentially stored in the image storage unit 25, and the filter processing was repeated on the filtered images and the collected images to finally remove the background. One image of contrast-enhanced cardiovascular only is stored in the image storage unit 25,
The results are displayed on the image display device 5.

Next, the image having the heartbeat phase is similarly filtered to obtain a contrast-enhanced cardiovascular image of the next phase. In this way, a contrast-enhanced cardiovascular image for one heartbeat is finally obtained.

Next, a procedure for obtaining a cardiac function diagram from the obtained contrast-enhanced cardiovascular image for one heartbeat will be explained.

The cardiac function measuring means 24 obtains a cardiac contour time change diagram using the threshold method. Further, the cardiac volume time diagram is created by determining the integrated value of the density of the internal region of the cardiac contour diagram determined above. In addition, for cardiac amplitude diagrams and cardiac phase diagrams, the maximum value of density, the heartbeat phase that shows the maximum value, and the heartbeat phase that shows the maximum and minimum values are determined for each image, the amplitude and phase are determined, and gray level conversion is performed. The images are then stored in the image storage section 25, respectively. Here, the processing can be speeded up by controlling the address of the image storage section 25 to be read.

The figures and images measured here are displayed on the image display device 5.
and sent for diagnosis. 4 and 5 schematically show embodiments of the present invention, and FIG.
Figure a shows a time-varying diagram of the concentration within the region of interest, in which heartbeat and contrast agent concentration changes are superimposed. The times at which radiation was actually exposed and images were collected are shown in 41 and 42. Reference numeral 41 shows a case where images before contrast imaging are collected and stored for two heartbeats, and reference number 42 shows a case where images during contrast imaging are collected and stored for three heartbeats. In addition, changes in heartbeat are shown in c.

FIG. 5 shows a case where time filter processing is applied to images collected and stored under the conditions of FIG. 4.

Images with the same phase are extracted for each heartbeat number (peat number) and multiplied by filter coefficients g1, g2, g3, g4, and g5 to create one image. here,
For example, if g1=g2=1/2 and g3=g=g5=-1/3, an image of only the contrast-enhanced cardiovascular blood vessels with the background removed can be obtained. The constraint here is ₅ 〓 ⁱ⁼¹ g1=0. In the end, an image for one heartbeat was finally created from images collected for five heartbeats.

According to this device, the heartbeat is matched with the collected radiation image group, and time filter processing is performed by determining the time filter coefficient according to the obtained heartbeat cycle, so there is no blurring of the motion due to the heartbeat. High-quality diagnostic images can now be obtained, and in a configuration that includes a contrast agent injection device, processing can be performed in accordance with time changes in the contrast agent concentration. ratio), and it is possible to obtain images that are easy to perform quantitative measurements. Furthermore, since it has a cardiac function measuring means, it is possible to easily obtain cardiac function measurement diagrams/images and measured values. Therefore, it becomes easier to diagnose the morphology and function of the cardiovascular system, and results such as a significant improvement in diagnosis can be obtained.

It should be noted that the present invention is not limited to the embodiments described above and shown in the drawings, and can of course be implemented with appropriate modifications within the scope of the gist thereof. For example, in the above embodiments, a concentration time change diagram is used to detect heartbeat Although this is done using an electrocardiogram measuring device, it is also possible to obtain the heartbeat cycle and its phase change from the electrocardiogram obtained from this device.

[Effects of the Invention] As detailed above, the present invention injects a contrast agent into the circulatory system of a subject, generates radiation with a radiation generator, and detects the radiation transmitted through the subject. A radiographic image signal is obtained, which is digitally converted into image data, and this image data is stored in a storage means, thereby creating a pre-contrast image and an image during contrast for at least one heartbeat. The collected image data is collected and stored in an apparatus that performs calculations on the collected image data to extract images of areas where there is a change in density from the image before contrast medium injection to the image during contrast medium injection, and use it for diagnosis. Knowing the heartbeat phase from image data,
A means for selecting images of the same heartbeat phase from among the stored images, and a processing means for creating an image of only the contrast-enhanced cardiovascular blood vessels for one heartbeat by respectively extracting the changing parts between the images of the same heartbeat phase. selects images with the same heartbeat phase from among the stored images from the collected image data, extracts changes between images with the same heartbeat phase, and removes backgrounds having the same heartbeat phase; A contrast-enhanced cardiovascular image for one heartbeat is created. This makes it possible to extract images of contrast-enhanced blood vessels from images synchronized with the heartbeat phase, and the present invention also provides an image system that collects and stores circulatory system radiographic images for at least two heartbeats of a subject. a collection storage means; a concentration time change creation means for determining a time change in concentration within a region of interest in the stored image; Using an image processing means to obtain a diagnostic image for one heartbeat by extracting the portions of change between the two heartbeats, the temporal change in concentration within the region of interest is determined from the circulatory system radiographic image for at least two heartbeats. From this, the images with the same heartbeat phase among the stored images are known, and the changing parts between the images with the same heartbeat phase are extracted to obtain a diagnostic image for one heartbeat. When generating the difference image from the transmitted image, it is now possible to obtain an image without blurring due to heartbeat, and therefore a high-quality image can be obtained, allowing for more accurate diagnosis. It is possible to provide a radiological diagnostic apparatus having the following characteristics.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention;
FIG. 2 is a block diagram showing the configuration of the image processing device.
FIG. 3 is a block diagram showing the configuration of the time filter processing means, and FIGS. 4 and 5 are diagrams for explaining the operation of the apparatus of the present invention. 1... X-ray generator, 2... Subject, 3... Image acquisition device, 4... Image processing device, 5... Image display device, 6... System controller, 7... System console, 8... X-ray generation control device, 9...
...Contrast agent injection device, 20... Image processing controller, 21... Concentration time change chart creation means, 22...
Heartbeat cycle detection means, 23... Time filter processing means, 24... Function measurement means, 25... Image storage unit, 26... Selector, 231, 232... Multiplier, 233... Adder.

Claims (1)

[Scope of Claims] 1. In an apparatus for detecting and displaying radiation transmitted through a subject while generating radiation from a radiation generator, and providing for diagnosis, the apparatus comprises: an image collecting and storing means for collecting and storing; a concentration time change creating means for calculating a time change in concentration within a region of interest in the stored image; and knowing which images have the same heartbeat phase among the stored images from the time change in concentration; 1. A radiological diagnostic apparatus comprising: an image processing means for obtaining a diagnostic image for one heartbeat by extracting changes between images of the same heartbeat phase. 2. Inject a contrast medium into the circulatory system of the subject, and while generating radiation with a radiation generator, detect the radiation transmitted through the subject to obtain a signal of the radiographic image of the subject, and convert this into digital. Converting the image data into image data and storing this image data in a storage means, thereby collecting and storing a pre-contrast image for at least one heartbeat and an image during contrast for at least one heartbeat, and regarding the collected image data. In a device that performs arithmetic operations to extract images of areas with density changes from images before contrast agent injection to images during contrast agent injection for diagnosis, the heartbeat phase is determined from the collected image data, and the above-mentioned method is used. A means for selecting images of the same heartbeat phase from among the stored images, and a processing means for creating an image of only contrast-enhanced cardiovascular blood vessels for one heartbeat by respectively extracting changes between images of the same heartbeat phase. A radiological diagnostic device characterized by: