JPS62167540A - X-ray image processing apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to an apparatus for processing X-ray fluoroscopic images, and in particular, it subtracts the image before injection from an image obtained by injecting a contrast agent into a blood vessel, etc. The present invention relates to a device that performs so-called digital subtraction processing, which cancels images and extracts only images of blood vessels, etc.

Conventional technology Traditionally, digital subtraction angiography (angiography with digital subtraction, DSA
), the maximum and minimum values of successive X-ray fluoroscopic images are stored in a peak hold memory, and subtraction is performed between the maximum and minimum images to determine the trajectory of the contrast agent, that is, the blood vessel image. It is proposed to extract According to this, it is possible to suppress the radiation dose to the subject and obtain a subtraction image with less noise.

Problems to be Solved by the Invention However, the above-mentioned conventional peak-hold type subtraction is not effective for moving objects (for example, the heart). In other words, peak holding images involves superimposing multiple images in the white direction or black direction, so any movement will result in blurring. For example, when trying to perform peak-hold DSA on coronary arteries, etc.,
Only a very blurred blood vessel image can be obtained.

SUMMARY OF THE INVENTION An object of the present invention is to provide an X-ray image processing apparatus that enables peak-hold subtraction even for images around a moving heart.

Means for Solving the Problems The X-ray image processing apparatus according to the present invention includes a recording means for recording X-ray image data for several heartbeats and electrocardiogram waveform data while associating them at the time of injection of a contrast medium, and a Means for reading out X-ray image data of a corresponding electrocardiographic phase for each heartbeat among the recorded X-ray image data of several heartbeats, and a maximum value of the X-ray image data of the corresponding electrocardiographic phase read out. and a peak hold means for holding the minimum value peak, and a calculation means for subtracting the minimum value image data from the held maximum value image data.

Function X-ray image data for several heartbeats during contrast agent injection and electrocardiogram waveform data are recorded in association with each other. This is what I did. In other words, due to the close relationship, it is possible to use the electrocardiogram waveform as an index to extract images of the corresponding electrocardiogram phase, and this makes it possible to extract images of the same phase from image data for several heartbeats. can. Therefore, by performing peak hold between image data whose phases correspond, it is possible to obtain a subtraction image in which only the image of the contrast agent appears clearly without image blurring.

Example In FIG. 1, the X of the subject obtained from the X-ray TV camera 1
The video signal of the fluoroscopic image is digitized via the A/D converter 2, and then sent to a recording device 3 such as a magnetic tape device or a node disk device, where it is recorded at a speed of, for example, 30 frames/second. recorded. At the same time, the subject's electrocardiographic waveform data measured by the electrocardiograph 4 at this time is sent to the recording device 3 and recorded.

This recording operation is performed from the time the contrast agent is injected into the subject and the contrast agent arrives at the imaging site until it flows away. Here, we will perform angiography of the right coronary artery, and in this case, the contrast medium will flow away after about 3 heartbeats.
The fluoroscopic image and electrocardiographic waveform are shown in FIGS. 2(a) and 2(b). In Figure 2 (a), the blacked out areas are contrast agents, A, A', A'' and B, B', Bo''.
are the corresponding electrocardiographic phases. Image data of multiple frames (approximately 30 frames) at each heartbeat ('C) are recorded in association with electrocardiographic waveform data.Each frame image of the second and third heartbeats corresponds to each frame image of the first heartbeat. are uniquely associated with each other using electrocardiographic waveform data as a medium. This operation is performed, for example, using the R wave of the electrocardiographic waveform as a reference and the delay time from it. In this way, the image data and Recording of electrocardiographic waveform data is performed for three heartbeats until the contrast agent flows away, and the recording operation ends.

Next, the image data recorded in the recording device 3 in this way is
It is read out by the CPU 5 as follows. First, the first frame image of the first heartbeat is read out, then the frame image of the corresponding phase of the second heartbeat is read out, and further,
The corresponding frame image of the third heartbeat is read out. In this way, for example, A, A" of the phase near the R wave in FIG.
, A'' are sequentially extracted (see FIG. 3(a)).

These images are then compared with each other, and the maximum value and minimum value are stored in the maximum value hold memory 6 and minimum value hold memory 7 for each picture cell, respectively. The maximum value hold memory image always represents a state in which there is no contrast agent, as shown in FIG. 3(b). The minimum value hold memory image shows the trajectory of the contrast agent as shown in Figure 3 (c), and when the image of A゛ of the third heartbeat is read out and the minimum value is held, the contrast agent that has flowed up to that point is displayed. The image of the trajectory of the contrast agent is completed.

In this maximum value hold and minimum value hold operation, each image being compared is an image taken at another heartbeat of the corresponding phase, so the images are almost the same except for the contrast agent, and no blurring occurs. .

The images in both memories 6.7 are subtracted by a subtractor 8, and only the contrast agent image is extracted. In other words, the subtraction image becomes as shown in FIG. 3(d), and the image of the trajectory of the contrast medium as it flows is gradually completed. The image thus completed is recorded again in the recording device 3, and at the same time, the electrocardiographic waveform data at that time is also recorded.

Then, ■ a specific phase in the heartbeat (for example, the phase of A)
This means that the blood vessel map image was recorded. Therefore, this operation is performed for all other phases, and blood vessel map images at each phase are recorded. Specifically, for all frame images of the first heartbeat, images of frames of the same phase of other heartbeats are read out, a peak hold operation is similarly performed, and then subtraction is performed.

In this way, all blood vessel map images at each phase within one heartbeat are recorded in the recording device 3, and if these are sequentially read out in the order of the phases and displayed on the display device 9 repeatedly for each heartbeat, A cine (moving image) display of a coronary artery map image can be realized, and blood vessel courses that are difficult to grasp in a two-dimensional image can be displayed in a form that is easier to understand.

In the above, a blood vessel map image of the right coronary artery was taken, but if you want to display blood vessel map images of the left and right coronary arteries on the same screen, first perform contrast imaging of either the left or right coronary artery as described above, and then obtain a fluoroscopic image. The image data and electrocardiogram waveform data are recorded in association with each other. Subsequently, the remaining one is contrast-enhanced, and the image data and electrocardiographic waveform data are recorded in association with each other. Then, similar to the phase matching of the fluoroscopic images of the left and right circular coronary arteries between each heartbeat, electrocardiographic waveform data is used as an intermediary, and peak hold subtraction between each heartbeat is performed simultaneously on the left and right sides. In this way, blood vessel map images of the left and right coronary arteries can be obtained on the same screen.

Effects of the Invention According to the present invention, it is possible to obtain a clear contrast agent image with less blur by performing peak-hold subtraction processing even for images around the heart that have large movements.

Moreover, by holding the peak, it is possible to reduce the radiation dose to the subject and reduce noise.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG.
A) is an image representing the fluoroscopic image at each time, Fig. 2 (b) is an electrocardiogram corresponding to Fig. 2 (a), and Fig. 3 (a) is an image representing each fluoroscopic image at the corresponding phase. FIG. 3(b) is an image representing a maximum value hold memory image, FIG. 3(c) is an image representing a minimum value hold memory image, and FIG. 3(d) is an image representing a subtraction image. l...X-ray TV camera 2...A/D converter 3.
... Recording device 4 ... Electrocardiograph 5 ... CPU
6...Maximum value hold memory 7...Minimum value hold memory 8...Subtractor 9...Display device A 3rd eye

Claims (1)

[Claims] (1) A recording means for recording X-ray image data for several heartbeats and electrocardiogram waveform data while correlating them at the time of contrast agent injection, and among the X-ray image data for several heartbeats recorded in the recording means, means for reading out X-ray image data of a corresponding electrocardiographic phase in each heartbeat; peak holding means for performing peak hold of the maximum value and minimum value of the read out X-ray image data of the corresponding electrocardiographic phase; An X-ray image processing device comprising: arithmetic means for subtracting minimum value image data from maximum value image data.