JPH0236097B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an image diagnostic apparatus such as an X-ray diagnostic apparatus.

[Technical background of the invention and its problems]

X-ray diagnostic equipment that adopts the digital radiography (hereinafter abbreviated as DR) method, which has recently been proposed in the field of X-ray diagnosis, converts fluoroscopic X-ray images into digital values and subtracts the digital image information. After performing image processing mainly on digital images, the images are converted back to analog images and displayed on a monitor.

Compared to conventional X-ray film-enhanced images, contrast-enhanced images produced by such X-ray diagnostic equipment make it possible to observe contrast with a thinner contrast agent concentration, allowing the visualization of each organ as a subject. It became possible to observe the contrast medium infiltrating from moment to moment. For example, if we take the heart as an object, there are coronary arteries that supply blood to the myocardium itself, and in order to observe the blood circulation state of these coronary arteries, a contrast agent is injected directly into the coronary arteries and X-ray photography is performed. ing. In this cardiac diagnosis, rather than observing the hemodynamics of the coronary arteries, it is better to directly observe the resulting myocardial ischemic state or the life or death of the myocardium by the infiltration distribution of the contrast medium. is often important.

In response to the above requirements, conventionally, the density of the specified ROI (region of interest) point A is changed over time, such as at time t ₁ to figure 1 a, at time t ₂ to figure 1 b, and at time t _o to figure 1 c. The changes over time can be observed by displaying a characteristic change graph with respect to concentration over time, as shown in FIG.

However, with this display method, the displayed
Although it is possible to know the density change of each pixel at the specified ROI point, it is not possible to display the shape of the boundary between the lesion and normal tissue within the organ, or the positional relationship of the lesion with respect to the overall shape of the organ, so it is not possible to display good diagnostic information. I couldn't get it.

[Purpose of the invention]

The present invention provides an image diagnostic apparatus that is capable of accurately diagnosing a subject by correlating and displaying at least two images with different density levels obtained by injecting a contrast medium into the subject. It is about providing.

[Summary of the invention]

The present invention provides a current image storage means for storing at least two images of the same subject having different density levels, a contour line level setting means for setting a contour line level at an image density level, and one image stored in the current image storage means. Level comparison means for determining whether the density level of each pixel of the image exceeds the contour line level set by the contour line level setting means, and position information of the pixel determined by the level comparison means to exceed the contour line level a contour line image storage means for storing the continuous relationship of pixels of the same density level as a contour line image by aggregating them; and a contour line image stored in the contour line image storage means and another image stored in the current image storage means. It is equipped with display means for integrally displaying the information.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 3 is a block diagram schematically showing an embodiment of an X-ray diagnostic apparatus according to the present invention.

In FIG. 1, 1 is an X-ray tube that irradiates X-rays to a subject 3 placed on a top plate 2.
is controlled by an X-ray controller 4 equipped with an X-ray power source. These X-ray tube 1 and X-ray controller 4 constitute an X-ray generator.

X-rays irradiated from the X-ray tube 1 transmit through the subject 3, and the transmitted X-rays are detected as a plane image by an X-ray detection device 5 consisting of, for example, an X-ray television.
The image information is given to the data processing device 6.
On the other hand, an electrocardiogram electrode 7 is connected to the subject 3, and an electrocardiogram signal ECG is obtained by an electrocardiograph 8. This electrocardiogram signal ECG (hereinafter abbreviated as ECG signal) is
The signal is converted into a digital signal by the A/D converter 9 and provided to the data processing device 6. In the figure, 10 is a monitor that displays image information obtained by image processing by the data processing device 6. 11 is an image file for filing the above image information.

Next, details of the data processing device 6 will be described with reference to FIG.

In FIG. 4, 12 is an A/D converter that converts image information (frame) output from the X-ray detection device 5 into digital values. 13 is image information (frame) outputted from the X-ray detection device 5 every time.
This is a bus selector that allocates the data to the image memory, which will be described later, in units of frames.

14A, 14B, and 14C are image memories, each of which stores digital image information. In this case, for example, the image memory 14A stores image information (mask image) at time t ₀ before contrast agent injection, the image memory 14B stores image information at time t 1 after contrast agent injection, and the image memory 14C stores image information (mask image) at time t ₀ before contrast agent injection. It is assumed that image information at time _t2 after drug injection is stored. Further, the image information (frames) stored in each of the image memory groups 14A, 14B, and 14C has a k×k matrix configuration, that is, pixel information E _(1,1) , as schematically shown in FIG. The pixel information is divided into ~E _(i,j) ~E _(k,k) and stored, and each pixel information has m-bit density (contrast agent concentration) information. Reference numeral 15 denotes a contour line level setting device for setting the density level when displaying a density contour line corresponding to the infiltrated contrast agent concentration level in the subject image. For example, when displaying n-level contour lines, 2 ⁿ
=p comparison levels D ₁ to D _i to D _p are set in advance.
16 uses each density setting level D _i in the contour line level setter 15 as a comparison standard _, and calculates the density _level ( This is a level comparator that determines whether or not the density information (expressed in m bits) exceeds the level. 17 is an image memory 14
A, 14B, 14C, it is a plain memory in which a k×k matrix configuration, that is, partitions F _(1,1) ~ F _{(i, j)} ~ _{F (k, k)} , is set. Section F _(1,1) ~
F _(i,j) to _{F (k,k)} are designed so that the density level can be expressed with n bits. 18 is a frame memory for storing images to be displayed; 19 is a D/A converter for converting the image information in the frame memory 18 into analog information for displaying on the monitor 10; 20;
converts the ECG signal from the electrocardiograph 8 to the level comparator 1
This is a timing setter that sets the timing when giving the signal to 6.

Next, the operation of this embodiment configured as described above will be described.

First, X-rays are irradiated before contrast medium injection (time t ₀ ), and the image information at that time is converted into pixel information E _0(1,1) ~ _{E 0(i,j)} ~
The image is divided into E _{0 (k,k)} and stored in the image memory 14A, and is used as a mask image in subtraction processing, for example. Next, time t ₁ after contrast medium injection
The image information at that time is divided into k×k pieces of pixel information E _{1 (1, 1)} ~ _{E 1 (i, j)} ~ _{E 1 (k, k) and} stored in the image memory 14B. Remember. At this time, the contour line level setter 15 sets 2 ⁿ = p comparison levels D ₁ in order to display n levels of contour line levels on the display target image.
Assume that ~D _i ~D _p are set.

Then, the comparison level D ₁ and the pixel information E _1(1,1) ~ _{E 1(i,j)} ~
E _1(k,k) are compared respectively, and this pixel information E _1(1,1) ~E _1(i,j)
~
For those in E _1(k,k) that exceed the comparison level D ₁ but do not exceed the comparison level D ₂ , the corresponding section F _(1,1) ~F _(i,j) ~F of the plain memory 17 Write data (comparison level D ₁ ) indicating the above comparison level D ₁ to _(k,k) . Sequentially, the above comparison process is performed at the comparison level D ₂ ~D _i ~
D _p is performed, and through this processing, it is determined which of the comparison levels D ₁ to D _i to _{D p} the density level of each pixel information in the image memory 14B corresponds to,
Corresponding section F _(1,1) ~ _{F (i,j)} ~ of plane memory 17
Data indicating the comparison levels D ₁ to D _i to D _p is written to F _(k,k) .

Note that during the above operation, the bus selector 13 is set so as to be able to take in the output of the level comparator 16 in order to write the comparison level to the plain memory 17.

Next, each section F _(1,1) of the plane memory 17 ~
The density information stored in F _(i,j) to _{F (k,k)} is sequentially read out, and the pixel information E1 _(1,1) to _{E1(i, j)} ~E _1(k,k) to the frame memory 18, and here the plain memory 1
The density contour data of No. 7 and the pixel information of the image memory 14B are combined to generate image information in which contour lines are set in the image to be displayed. This image information is then converted into analog information by a D/A converter 19 and displayed as an image on the monitor 10. In this case, image information at t ₁ after contrast agent injection is stored in the image file 11, if necessary.

Next, at time _t2 after the contrast medium is injected, X-rays are irradiated, and image information at that time is stored in the image memory 14C. Then, the same processing as at time _t1 is performed and the image is displayed on the image monitor 10 on which contour lines have been set. In the above, the image information at time t ₀ in the image memory 14A is used as a mask image, and the image information at times t ₁ and t ₂ in the image memories 14B and 14C is subtracted to perform contour line setting in the above embodiment. You may also do so.

A case will be described in which a heart as shown in FIG. 6 is specifically diagnosed as a subject using the above embodiment. That is, a contrast agent is injected into the coronary artery 22 from the catheter (syringe) 21 to visualize the stenosis in the illustrated area. Furthermore, the contrast medium gradually infiltrates the entire myocardium 23, and density contrast begins to appear. If there is stenosis in the illustrated area, causing an abnormality in the heart, for example, the myocardium in the illustrated area is damaged,
There is no or very little blood circulation. Therefore, no density contrast occurs near the illustrated portion. If the density contour line display operation according to this embodiment is performed in such a state, the illustrated contour lines 23, 24, 25, and 26 will be displayed due to the density contrast caused by the infiltration of the contrast agent, and this will cause the illustrated area to be displayed from the entire imaging area. The relative positional relationship of the heart to the whole heart, the range of the inactive area, etc. can be easily determined, and important information for cardiac diagnosis can be provided.

Furthermore, in the above embodiment, a case was described in which the phase of the cardiac cycle was not taken into consideration, but in FIG.
The ECG signal is applied to the level comparator 16 via the timing setter 20, image information of the same phase of the cardiac cycle is selected, and the contour line display operation of the above embodiment is performed on the image information of the same phase. Modifications may also be made.

Furthermore, the image information from the X-ray detection device 5 is converted into an A/D
After A/D conversion by the converter 12, after subtracting the scattered radiation component due to X-rays, a means for logarithmic conversion is provided,
The digital image information after logarithmic conversion may be modified to perform the contour line display operation of the above embodiment.

Other embodiments of the present invention can be implemented with various modifications without departing from the spirit of the present invention.

〔Effect of the invention〕

As described above, according to the present invention, for example,
In the case of X-ray diagnosis using the DR method, it is possible to clarify the positional relationship of the lesion in the entire subject and the center of the lesion. The subject can be diagnosed accurately by displaying at least two images having different density levels obtained by correlating with each other.

[Brief explanation of drawings]

Figures 1a, b, and c are diagrams for explaining the operation of an X-ray diagnostic device that employs the digital radiography method; Figure 2 is a characteristic diagram showing changes in contrast agent concentration over time; Figure 3 4 is a block diagram showing details of the data processing device in FIG. 3, and FIG. 5 explains the configuration of the image memory in FIG. 4. FIG. 6 is a schematic diagram showing an image of a heart as a subject for explaining the operation of an embodiment of the present invention. 1... X-ray tube, 2... Top plate, 3... Subject, 4
...X-ray controller, 5...X-ray detection device, 6
...Data processing device, 7...Electrocardiogram electrode, 8...
Electrocardiograph, 9... A/D converter, 10... Monitor,
11...Image file, 12...A/D converter,
13...Bus selector, 14A, 14B, 14C
... Image memory, 15 ... Contour line level setter, 16 ... Level comparator, 17 ... Plain memory, 18 ... Frame memory, 19 ... D/A
Converter, 20...timing setter.

Claims (1)

[Scope of Claims] 1. Current image storage means for storing at least two images of the same subject having different density levels; contour line level setting means for setting contour line levels at image density levels; level comparison means for determining whether the density level of each pixel of the first image exceeds the contour line level set by the contour line level setting means; A contour line image storage means for storing the continuous relationship of pixels of the same density level as a contour line image by collecting position information, and a contour line image stored in the contour line image storage means and other information stored in the current image storage means. An image diagnostic apparatus characterized by comprising a display unit that integrally displays an image. 2 At least two images of the same subject having different density levels stored in the current image storage means are an X-ray image before contrast medium injection and an X-ray image after contrast medium injection.
2. The image diagnostic apparatus according to claim 1, wherein the image is either a X-ray image or an image obtained by subtracting an X-ray image before contrast medium injection from an X-ray image after contrast medium injection. 3. The image according to claim 1, wherein the display means superimposes and displays the contour line image stored in the contour line image storage means and another image stored in the current image storage means. Diagnostic equipment.