JPH0790022B2 - X-ray image processing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for processing an X-ray fluoroscopic image, and particularly to a background in which an image before injection is subtracted from an image obtained by injecting a contrast agent into a blood vessel or the like. The present invention relates to a device that performs so-called digital subtraction processing that cancels an image and extracts only an image of a blood vessel or the like.

2. Description of the Related Art Conventionally, in digital subtraction angiography (vascular subtraction method by digital subtraction, abbreviated as DSA), the maximum and minimum values of consecutive X-ray fluoroscopic images are stored in a peak hold memory, and the maximum and minimum images are stored. It has been proposed to extract the trajectory of the contrast agent, that is, the blood vessel image by performing subtraction with the value image. According to this, the exposure dose to the subject can be suppressed and a subtraction image with less noise can be obtained.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, the above-mentioned conventional peak hold type subtraction is not effective for a moving object (for example, heart). That is, the peak hold of the image is performed because a plurality of images are overlapped in the white direction or the black direction, and when there is a motion, the image is blurred. For example, if you try to perform peak hold DSA for coronary arteries,
Only a very blurred image of blood vessels can be obtained.

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

Means for Solving Problems The X-ray image processing apparatus according to the present invention is a means for obtaining X-ray image data by performing X-ray photography, an electrocardiographic measurement means for obtaining electrocardiographic waveform data, and a contrast medium injection method. Recording means for recording the X-ray image data and the electrocardiographic waveform data in the above-mentioned several heartbeat periods in association with each other in one X-ray imaging for several heartbeat periods, and the number recorded in the recording means. Heart rate X
Of the line image data, means for reading the X-ray image data of the corresponding cardiac potential phase at each heartbeat, and peak hold for performing maximum and minimum peak hold of the read X-ray image data of the corresponding cardiac potential phase. And means for subtracting the minimum value image data from the held maximum value image data for each of the cardiac potential phases.

Action When X-ray imaging is performed to obtain X-ray image data, at the same time, electrocardiographic waveform data is taken by the electrocardiographic measuring means and recorded while being associated with each other. Such X-ray imaging is performed during a period of several heartbeats when the contrast agent is injected. Due to the close relationship between the movement of the heart and the electrocardiographic waveform, the electrocardiographic waveform can be used as an index to extract an image of the corresponding electrocardiographic phase, which allows recording of several heartbeats recorded as described above. It is possible to take out the data having the same phase from the image data of. Therefore, if peak hold is performed between the image data corresponding to this phase, it is possible to obtain a subtraction image for each electrocardiographic phase in which no blurring of the image appears and only the image of the contrast agent clearly appears. You can A clear subtraction image is obtained for each electrocardiographic phase by performing only one X-ray photography during the period of several heartbeats at the time of injection of the imaging agent, that is, without performing X-ray photography without the imaging agent. Can be obtained.

Practical example In FIG. 1, the video signal of the X-ray fluoroscopic image of the subject obtained from the X-ray TV camera 1 is digitized through the A / D converter 2, and then the magnetic tape device, the hard disk device, etc. It is sent to the recording device 3 and recorded at a speed of, for example, 30 frames / sec. At the same time, the electrocardiographic waveform data of the subject 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 when the contrast agent is injected into the subject and the time when the contrast agent reaches the imaging site until it flows away. Here, it is assumed that the blood vessel image of the right coronary artery is imaged, and in this case, the contrast medium flows away in about 3 heartbeats,
The perspective image and the electrocardiographic waveform are as shown in FIGS. 2 (a) and 2 (b). The blackened portions in FIG. 2 (a) are contrast agents, and A, A ', A "and B, B', B" are the corresponding cardiac potential phases. The image data of a large number of frames (about 30 frames) at each heartbeat is recorded in association with the electrocardiographic waveform data. Each frame image of the second and third heartbeats corresponding to each frame image of the first heartbeat is uniquely associated with the electrocardiographic waveform data as a medium.
This operation is performed, for example, with reference to the R wave of the electrocardiographic waveform and the delay time from that. In this way, the image data and the electrocardiographic waveform data associated with each heartbeat are recorded for three heartbeats until the contrast agent flows away, and the recording operation is completed.

Next, the image data recorded in the recording device 3 in this way is
It is read by the CPU 5 as follows. First, the first frame image of the first heartbeat is read, then the frame image of the corresponding phase of the second heartbeat is read, and the third frame image is read.
The frame image corresponding to the heartbeat is read. Thus, for example, the phases A, A'in the vicinity of the R wave in FIG.
The images of A ″ are sequentially extracted (see FIG. 3B). These images are compared with each other, and the maximum value is held in the maximum value hold memory 6 and the minimum value is held in the minimum value for each picture cell. Each is stored in the memory 7. The maximum value hold memory image always represents a state without a contrast agent as shown in Fig. 3 (b), and the minimum value hold memory image is shown in Fig. 3 (c). This represents the trajectory of the contrast agent, and when the image of A ″ at the third heartbeat is read out and the minimum value is held, the image of the trajectory of the contrast agent that has flown until then is completed.

In the maximum value hold operation and the minimum value hold operation, each image to be compared is an image at another heartbeat of a corresponding phase, so that the images are almost the same except for the contrast agent, and no blur occurs. .

The images in both memories 6 and 7 are subtracted by the subtracter 8 to extract only the image of the contrast agent. That is, the subtraction image becomes as shown in FIG. 3D, and the image of the locus when the contrast medium 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 one heartbeat (for example, the phase of A)
It means that the blood vessel map image at was recorded. Therefore, this operation is performed for all other phases, and the blood vessel map image in each phase is recorded. Specifically, for the images of all the frames in the first heartbeat, the images of the frames of the same phase in the other heartbeats are read out, the peak hold operation is similarly performed, and then the subtraction calculation is performed.

In this way, all blood vessel map images in each phase within one heartbeat are recorded in the recording device 3. If this is sequentially read out in the order of the phases and is repeatedly displayed on the display device 9 for each heartbeat, It is possible to realize a cine (moving image) display of a coronary artery map image, and it is possible to represent a blood vessel running that is difficult to grasp in a two-dimensional image in a form that is easier to grasp.

In the above, the vascular map image of the right coronary artery was taken, but if you want to display the vascular map image of both the left and right coronary arteries on the same screen, first, take one of the left and right contrast imaging as above and see through the fluoroscopic image. The image data and the electrocardiographic waveform data are recorded in association with each other. Next, perform the remaining contrast imaging,
The image data and the electrocardiographic waveform data are recorded in association with each other.
Then, as in the case where the fluoroscopic images of the left and right coronary arteries are topologically associated with each heartbeat, the electrocardiographic waveform data is used as a medium to perform peak hold subtraction simultaneously between the heartbeats. Thus, the 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 X-ray image processing apparatus of the present invention, by performing the peak hold type subtraction processing, it is possible to obtain a clear contrast agent image with little blur even for an image around the heart where the motion is large. Further, the peak hold can reduce the exposure dose of the subject and the noise. Moreover, a clear subtraction image can be obtained for each cardiac potential phase without performing X-ray imaging in the absence of a contrast agent for obtaining a mask image. A single X-ray is taken during the injection of the contrast agent for a period of several heartbeats, and the peak-hold subtraction process is performed using the X-ray image data collected there, so that clear subtraction is performed for each cardiac potential phase. You can get a statue.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 (a) is an image showing a perspective image at each time, and FIG. 2 (b).
Is an electrocardiographic waveform diagram corresponding to FIG. 2 (a), FIG. 3 (a) is an image showing each perspective image at a corresponding phase, and FIG. 3 (b).
Is an image showing the maximum value hold memory image, FIG.
Is an image showing the minimum value hold memory image, FIG. 3 (d)
Is an image representing a subtraction image. 1 ... 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

Claims (1)

[Claims] 1. A means for obtaining X-ray image data by performing X-ray photography, an electrocardiographic measurement means for obtaining electrocardiographic waveform data, and a single X-ray photography for a period of several heartbeats at the time of injecting a contrast medium. A recording means for recording the X-ray image data and the electrocardiographic waveform data in the period of the above-mentioned several heartbeats in association with each other, and among the X-ray image data for several heartbeats recorded in the recording means, for each heartbeat Means for reading the X-ray image data of the corresponding cardiac potential phase, peak holding means for holding the maximum and minimum values of the read X-ray image data of the corresponding cardiac potential phase, and each of the cardiac potential phases An X-ray image processing apparatus further comprising: a calculating unit that subtracts the minimum value image data from the held maximum value image data.