JPS61252779A - Dsa device - Google Patents

Abstract

PURPOSE:To obtain a picture suitable for dynamic analysis by obtaining a periodical peak hold DSA image representing a progress on the way of a contrast medium in flowing and a main peak hold DSA image representing a whole locus of the contrast medium equal to an ordinary peak hold DSA image. CONSTITUTION:In the case of a live image, memories 3, 4 are periodically reset in a fixed period by a controller 5. A peak hold DSA image obtained by subtracting the picture stored in the memories 3, 4 in a subtraction circuit 6 becomes a periodical peak hold DSA image. Namely, in a period 1, the contrast medium does not reach to a photographing section, from a period 2, starts to enter and at a period 6 reaches to an end of the photographing section. The live image indicates the contrast medium at that period. Thereby, since the periodical peak hold DSA image is subtraction image between the peak hold images within the respective periods, it indicates a change in the period and by this periodical peak hold DSA image, a dynamic analysis can be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a DSA device (digital subtraction angiography device), and particularly to a peak-hold type DSA device.

Conventional technology DSA equipment digitally subtracts (subtracts) the video signal of an X-ray transmission image obtained by an X-ray TV fluoroscopy system.
The image without contrast agent is used as a mask image,
By subtracting the mask image from the live image of the contrast agent flowing through the imaging area, only the image created by the contrast agent is extracted from the background image, and is particularly useful for diagnosing blood vessels. .

In a peak-hold type DSA device, the same pixel is compared between images of many frames from before the contrast agent arrives at the imaging site until after it has flowed away, and the maximum and minimum pixel signals are compared. pixel signals are stored in each of two frame memories, and subtraction is performed between them. In other words, the frame memory on one side stores the pixel signal with the maximum value over the entire period of shooting, so, for example, only the background image is formed, and the other frame memory stores the pixel signal with the maximum value over the entire period of shooting. Since the pixel signals are stored, an image of, for example, the trajectory of a contrast agent appearing in a background image is formed. By subtracting between these, only an image in which only the contrast agent portions of images obtained in increments as the contrast agent trajectories, that is, the contrast agent flows, are superimposed is extracted.

Problems to be Solved by the Invention Incidentally, in a peak-hold type DSA device, the peak-hold DSA image that is left as the final image is a single image (representing the trajectory of the contrast agent) that is completed after the contrast agent has flowed away. ) only.

Therefore, such a peak hold DSA image is certainly useful for morphological analysis such as blood vessel occlusion, but is insufficient for dynamic analysis such as blood flow measurement.

An object of the present invention is to provide a peak-hold type DSA device that is improved so as to be able to obtain images suitable for dynamic analysis.

Means for Solving the Problems The DSA device according to the present invention compares the signals of each pixel of a video signal of an X-ray transmission image obtained by an X-ray TV fluoroscopy system between frames, and stores the larger one. A value peak hold image storage means, a minimum value peak hold image storage means for comparing the signals of each pixel of the video signal between frames and storing the smaller one, and the maximum value peak hold image and the minimum value peak hold. A subtracting means for performing subtraction between the image and the image, a recording means for recording the image after the subtraction, and when a live image is obtained, the maximum value and minimum value peak hold image storage means are both periodically reset. A periodic peak hold DSA image is obtained from the subtraction means, and this periodic peak hold DSA image is recorded in the recording means, and the reproduced image from this recording means is stored in the maximum value and minimum value peak hold image storage. and control means for controlling the subtraction means to perform a peak hold operation over the entire period to obtain a main peak hold DSA image from the subtraction means.

By periodically resetting both the maximum value and minimum value peak hold image storage means while a live image is being sent, the subtraction means can store the peak hold DSA image within that period every cycle. can be obtained. Since this is recorded, if this is played back and the maximum value peak hold operation and minimum value peak hold operation are performed again over the entire period for the reproduced image, the subtraction means will calculate the normal peak value over the entire period for the live image. A main peak hold DSA image similar to the hold DSA image can be obtained.

Embodiment In FIG. 1, a changeover switch 1 is used to switch between a video signal of an X-ray transmitted image obtained by an X-ray TV fluoroscopy system and a video signal of a reproduced image from a recording device 10.
being thrown to the side. At this time, X-ray exposure starts in the X-ray TV fluoroscopy system, and a video signal of a live image is sent. This video signal is converted into a digital signal by an A/D converter 2 and sent to a maximum value peak hold memory 3 and a minimum value peak hold memory 4.

The maximum value peak hold memory 3 performs a maximum value peak hold image storage operation in which the signals of each pixel are compared between frames and the larger one is stored, and the minimum value peak hold memory 4 performs a maximum value peak hold image storage operation in which the signal of each pixel is stored. A minimum value peak hold image storage operation is performed in which frames are compared and the smaller one is stored. For live images, these memories 3.4
is periodically reset by the controller 5 at regular intervals. Therefore, the peak hold DSA image obtained by subtracting the images stored in the memories 3 and 4 from each other in the subtraction circuit 6 becomes a periodic peak hold DSA image. In other words, as shown in Fig. 2, if the contrast agent does not reach the imaging site in period 1, begins to arrive in period 2, and reaches the end of the imaging site in period 6, the live image will not reach the imaging site in period 1. Since it represents the contrast agent of As shown in FIG. 2(b), this periodic peak-hold DSA image, which represents the trajectory of the flow of the contrast agent within the period, is displayed via the emphasis circuit 7 and the D/A converter 8. The image is sent to the device 9, where it is displayed as shown in FIG. 2(b), and is sent to the recording device l.
It is sent to O and recorded. In this way, periodic peak-hold DSA images are recorded in many cycles until the contrast agent flows away from the imaging site, and when the contrast agent flows away, the X-ray TV fluoroscopy system finishes X-ray exposure and the DSA Recording of the statue also ends. Dynamic analysis can be performed using this periodic peak-hold DSA image.

Next, when performing morphological analysis, a regular peak hold DSA image (herein referred to as a main peak hold image) is obtained from the periodic peak hold DSA image reproduced from the recording device 10.
get. In this case, the changeover switch 1 is turned to the B side, and the reproduced image is sent through the A/D converter 2 to the maximum value peak hold memory 3 and the minimum value peak hold memory 4.

At this time, these memories 3.4 are reset only once by the controller 5 at the beginning and are not reset periodically thereafter, and the maximum value peak hold operation and the minimum value peak hold operation are performed over the entire period. It will be done. Therefore, since periodic peak hold DSA images are sent sequentially as shown in FIG. 2(b), the subtraction circuit 6
As shown in Figure 2(e), the normal peak hold D
Images similar to the SA image appear one after another, and finally an image of the trajectory of the contrast medium over the entire period, for example, a panoramic view of blood vessels, is obtained. Therefore, morphological analysis can be performed using this main peak hold DSA image.

Effects of the Invention According to the present invention, a periodic peak-hold DSA image representing the intermediate progress of a flowing contrast agent, and a main peak-hold DSA image representing the entire trajectory of the contrast agent, which is the same as a normal peak-hold DSA image. can be obtained. Therefore, dynamic analysis can be performed using periodic peak-hold DSA images, and morphological evidence can be obtained using main peak-hold DSA images.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG.
), (b), and (C) are live images in each period, respectively.
Periodic peak hold DSA image, main peak hold DS
It is a figure showing A image.

Claims (1)

[Claims] (1) Maximum peak hold image storage means for comparing the signals of each pixel of a video signal of an X-ray transmission image obtained by an X-ray TV fluoroscopy system between frames and storing the larger one; minimum value peak hold image storage means for comparing signals of each pixel between frames and storing the smaller one;
a subtraction means for performing subtraction between the maximum value peak hold image and the minimum value peak hold image; a recording means for recording the image after the subtraction; and when a live image is obtained, the above maximum value and minimum value peak hold image. The image storage means are both reset periodically to obtain a periodic peak hold DSA image from the subtraction means, and this periodic peak hold DSA image is recorded in the recording means, and the reproduced image from this recording means is control means for controlling the peak hold operation by the maximum value and minimum value peak hold image storage means to be performed over the entire period to obtain a main peak hold DSA image from the subtraction means;
SA device.