JP2005253844A - Device and program of analyzing tomographic image of brain - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simpler image processing device for diagnosing the cerebral apoplexy for the purpose of further reducing the burden on a patient. <P>SOLUTION: The problem can be solved by obtaining two tomographic images (a control image and a peak image) based on a pigment dilution curve and obtaining the image of difference of the two images by using the cerebral tomographic image analyzing device for analyzing a tomographic image of the brain obtained by the CT or MRI. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to analysis processing of image data taken in the medical field.

  Conventionally, in the medical field, a lot of image data has been used for diagnosis and research. For example, X-ray CT (Computed Tomography) and MRI (Magnetic Resonance Imaging) are often used in the diagnosis of stroke. Both of these can take a tomographic image of the brain. And blood flow can be grasped | ascertained by performing image processing about the image image | photographed using these, and many analysis methods of this image have been reported (for example, nonpatent literature 1).

  One of the analysis methods is a deconvolution method. For example, a certain change occurs in an artery, and the change appears in the vein. At this time, the change appears in the vein through various decorations. The deconvolution method examines what is happening in the capillaries. Many of the deconvolution methods are calculated by Fourier transform or Laplace transform. There is also this simple method (for example, Non-Patent Document 2).

Another analysis method is trigonometry (Trapez). The trigonometric method is a method of calculating whether or not the blood flow velocity is faster than the size of the area of the triangle by taking three points of the peak portion of the obtained dye dilution curve and the flat portions at both ends thereof.
ISTVAN SCHISZLER, MINORU TOMITA, YASUO FUKUCHI, NORIO TANAHASHI, AND KOJI INOUE "New optical method for analyzing cortical blood flow heterogeneity in small animals: validation of the method", (US), Am J Physiol Heart Circ 279, 2000 years, H1291 -H1298 Satoshi Hamada, “Indicator transit time distribution function in organs—a simple method of devolution”, Ayumi Medicine, Ishigaku Shuppan Co., Ltd., 1973, 84, p. 137-p. 138

  However, in the above conventional method, in order to obtain an image of an ischemic portion (a portion where arterial blood flowing locally decreases and a blood supply necessary for tissue is insufficient), a complicated calculation based on enormous information is performed. Had gone. The time until the result is obtained depends on the performance of hardware such as the processing speed of the computer. Also, such computers were expensive and not found in any medical institution. Also, the amount of CT X-ray exposure is currently a problem.

  In view of the above-described problems, the present invention provides a brain tomographic image analysis apparatus for diagnosing stroke, which is simpler and more aimed at reducing the burden on the patient, and a program thereof.

  According to the first aspect of the present invention, in the brain tomographic image analyzing apparatus for analyzing a tomographic image of the brain, the same tomographic image of the brain is photographed and there is a predetermined time difference between them. A cerebral tomographic image analysis apparatus comprising: an acquisition unit that acquires the two tomographic images; and a tomographic image difference unit that obtains a difference between gradation values of pixels corresponding to coordinates between the tomographic images. Can be achieved by providing.

With this configuration, if a cerebrovascular disorder site exists, the site can be recognized in the difference image.
According to the second aspect of the present invention, the tomographic image analysis device according to claim 1, wherein the tomographic image is a CT image or an MRI image. Can be achieved by providing.

With this configuration, it is possible to analyze an image captured by CT or MRI.
According to the third aspect of the present invention, the acquisition unit is configured to determine the abundance of the angiographic agent administered to the subject to be imaged of the tomographic image with respect to time in the brain. 2. The brain tomographic image analysis apparatus according to claim 1, wherein the two tomographic images having the predetermined time difference are acquired based on a distribution.

With this configuration, it is possible to select two tomographic images in which the abundance ratio of the angiographic contrast agent is the largest.
According to the invention described in claim 4 of the present invention, one of the two tomographic images is the tomographic image when the abundance is maximum, and the other is the angiographic contrast agent. This can be achieved by providing the tomographic image analysis apparatus according to claim 3, wherein the tomographic image is before administration of the brain.

With this configuration, a clearer difference image can be obtained.
According to the invention described in claim 5 of the present invention, in the brain tomographic image analysis program for causing a computer to execute a process of analyzing a brain tomographic image, the same tomographic image of the brain is photographed, A brain tomography that causes a computer to execute an acquisition process for acquiring two tomographic images having a predetermined time difference and a tomographic image difference process for obtaining a gradation value difference between pixels corresponding to each other between the tomographic images This can be achieved by providing an image analysis program.

With this configuration, if a cerebrovascular disorder site exists, the site can be recognized in the difference image.
According to the invention described in claim 6 of the claim, the tomographic image is a CT image or an MRI image. The brain tomographic image analysis program according to claim 5, Can be achieved by providing.

With this configuration, it is possible to analyze an image captured by CT or MRI.
According to the seventh aspect of the present invention, the acquisition processing includes determining the abundance of the angiographic agent administered to the subject to be imaged of the tomographic image with respect to time in the brain. The two tomographic images having the predetermined time difference are acquired based on the distribution, and this can be achieved by providing the brain tomographic image analysis program according to claim 5.

With this configuration, it is possible to select two tomographic images in which the abundance ratio of the angiographic contrast agent is the largest.
According to the invention described in claim 8, the problem is that one of the two tomographic images is the tomographic image when the abundance is maximum, and the other is the angiographic contrast agent. It can be achieved by providing the tomographic image analysis program according to claim 7, wherein the tomographic image is before administration of the brain.

  With this configuration, a clearer difference image can be obtained.

  In order to diagnose a stroke, it is not necessary to perform a complicated calculation on the tomographic image of the brain acquired using CT, MRI, etc., and the same result as that obtained by such a calculation is obtained. It can be determined easily and quickly. In addition, since the X-ray is applied only twice in CT, the amount of X-ray exposure to the patient can be significantly reduced.

  In the present invention, a cerebrovascular disorder site is specified by taking a difference between two predetermined images taken with CT or MRI and having a time difference. Such a method is called a subtraction method or an auto radiograph method.

  FIG. 1 shows an image analysis apparatus 1 according to this embodiment. In FIG. 1, the image analysis apparatus 1 includes at least a mass storage device 2, a memory 3, an output interface 5, an input interface 8, a CPU (central processing unit) 10, and a bus 4 for connecting them. A display device 6 is connected to the output interface 5, and an imaging device 7, an input device 9, and the like are connected to the input interface 8.

  As an example of the large-capacity storage device 2, various types of storage devices such as a hard disk and a magnetic disk can be used, and a flow program and the like to be described later are stored. This program is read by the CPU 10, and each process of the flow is executed. Further, the mass storage device 2 stores CT images, MRI images, and the like taken by the imaging device 7 such as CT and MRI, as will be described later.

The memory 3 is a storage device such as a RAM (Random Access Memory) and a ROM (Read Only Memory) used in various processes. The display device 6 is a display or the like.
The input device 9 includes a keyboard, mouse, or electronic camera, microphone, scanner, tablet, storage medium (flexible disk, CD, CD-ROM, CD-R, DVD, DVD-R, DVD-ROM, memory card). Etc.) can be used. In addition, other peripheral devices can be connected.

The imaging device 7 is CT or MRI. Further, the present invention is not limited to these, and any apparatus may be used as long as it can acquire a cerebral blood vessel image for diagnosing the blood flow state of the brain.
Further, the CT image and MRI image stored in the mass storage device 2 may be stored via the communication network from the imaging device 7, or the CT image or MRI image stored in the storage medium or the like is read. It may be read and stored by the device.

  FIG. 2 shows a flow in the present embodiment. First, when imaging a tomographic image of the brain using the imaging device 7, an angiographic contrast agent is administered to the subject, so a tomographic image of the brain at the start of the administration is imaged (step S1, hereinafter referred to as S). Abbreviated). The image at this time is hereinafter referred to as a control image. FIG. 3 shows a control image in the present embodiment. In addition, about imaging | photography of a control image, it may be before administration of an angiographic contrast agent and after administration. Note that the control image is stored in the mass storage device 2 after photographing.

  Next, a tomographic image of the brain when the administered contrast agent is the most in the brain is taken using the imaging device 7 (S2). Hereinafter, the image at this time is referred to as a peak image. FIG. 4 shows a peak image in the present embodiment. Here, it is about how much the amount of contrast agent peaks after administration of the contrast agent, and this will be described with reference to FIGS. Note that the peak image is stored in the mass storage device 2 after photographing.

  FIG. 5 shows a dye dilution curve of the ischemic part, FIG. 6 shows a vein dye dilution curve, FIG. 7 shows a brain tissue dye dilution curve, and FIG. 8 shows an arterial dye dilution curve. The pigment referred to here is a pigment contained in the contrast agent, and the pigment dilution curve represents a change in the concentration (abundance) of the pigment in the brain. 5 to 8, the vertical axis represents a value corresponding to the concentration of the dye, and the horizontal axis represents time (seconds).

  6 to 8, in any case, the luminance value is highest in the vicinity of 15 to 20 seconds after the contrast medium is administered. This indicates that the administered pigment (contrast agent) has the largest amount of pigment present in the brain in about 15 to 20 seconds. Therefore, in this embodiment, the peak image should be taken for 16 to 20 seconds, preferably about 17 seconds after administration of the contrast agent. Since this time varies among individuals, it is necessary to measure the time from the vein of the subject to the brain before the examination.

  Further, FIG. 5 shows a dye dilution curve of an ischemic part. From this, it is possible to confirm the light intensity, the Hansfield value (darkness) of the X-ray, or the T2 value of MRI. That is, it is possible to examine how much blood is flowing to the site from this dye dilution curve.

  Next, the difference between the image acquired at S1 (control image) and the image acquired at S2 (peak image) is taken (S3). Specifically, the pixel value of each pixel in one image is obtained by subtracting the pixel value of the pixel in the other image corresponding to each pixel. An image obtained by taking the difference in this way is hereinafter referred to as a difference image. The most preferable difference image is a difference image when the image before using the contrast medium is a control image and the image at the highest density is a peak image.

  FIG. 9 is a difference image between the control image of FIG. 3 and the peak image of FIG. In this difference image, it can be seen that the lower right portion of the cross section of the brain is particularly dark. Here, the image of FIG. 9 and the images (FIGS. 10 and 11) of the ischemic region analyzed by the conventional method will be compared below.

  FIG. 10 is a tomographic image analyzed using the deconvolution method. In this image, there is a markedly dark part in the lower right part, which indicates an ischemic part. FIG. 11 is an analyzed image obtained using trigonometry. In this image, only the lower right part is clearly different from the other part (dark part), and this part shows an ischemic part.

Similar to the results obtained by these conventional methods (FIGS. 10 and 11), the image (FIG. 9) obtained in the present embodiment also displays the lower right portion of the cross section of the brain particularly dark.
If this is considered by applying the theory of blood flow measurement method called Autographic method, in short, there is little blood going there, but since there is little blood flow, it is considered that the amount carried into there is also small. In other words, it can be imagined that blood flow is small because the amount actually carried is small.

  As described above, the present invention can obtain the same result as compared with the analysis method conventionally used in the medical field. In the above description, an image obtained when the amount of the contrast medium in the brain is the largest is used as the peak image. However, the present invention is not limited to this. That is, if there is a time difference between the two brain tomographic images, that is, if there is a difference in angiographic contrast concentration (abundance difference), the image may not be a peak image. In addition, since the present invention is intended to be viewed from the viewpoint of blood flow, brain tomographic images of all strokes (“cerebral infarction”, “cerebral hemorrhage”, “subarachnoid hemorrhage”, “transient ischemic attack”, etc.) Can apply.

  As described above, the diseased part of the cerebrovascular disorder has been conventionally analyzed by performing complex calculations from images acquired by CT, MRI, etc. In the present invention, the difference between two CT images or MRI images having a time difference is analyzed. By taking this, the same result as before can be obtained. Therefore, since a huge amount of calculation is not required as in the prior art, hardware resources such as a memory can be saved, and a result can be obtained easily and quickly.

  In addition, since blood flow images can be taken even with CT that does not perform well, it has been necessary to go to a large facility or university hospital to measure cerebral blood flow. Blood flow can be measured. Moreover, since the present invention applies X-rays only twice, the amount of X-ray exposure to the patient can be significantly reduced.

It is a figure which shows the image analysis apparatus in this embodiment. It is a figure which shows the flow in this embodiment. It is a figure which shows the control image in this embodiment. It is a figure which shows the peak image in this embodiment. It is a figure which shows the pigment dilution curve of an ischemic part. It is a figure which shows the pigment | dye dilution curve of a vein. It is a figure which shows the pigment | dye dilution curve of a brain tissue. FIG. 8 is a diagram showing an arterial pigment dilution curve. It is a figure which shows the difference image of the control image of FIG. 3, and the peak image of FIG. It is a figure which shows the image analyzed using the deconvolution method. It is a figure which shows the analyzed image obtained using the trigonometric method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image analysis device 2 Mass storage device 3 Memory 4 Bus 5 Output interface 6 Display 7 Imaging device 8 Input interface 9 Input device

Claims (8)

In a brain tomographic image analyzer that analyzes a tomographic image of the brain,
An acquisition means for imaging the same tomographic image of the brain and acquiring the two tomographic images having a predetermined time difference from each other;
A tomographic image difference means for taking a difference in gradation values of pixels corresponding to coordinates between the tomographic images;
A brain tomographic image analysis apparatus comprising:   The brain tomographic image analysis apparatus according to claim 1, wherein the tomographic image is a CT image or an MRI image.   The acquisition means acquires the two tomographic images having the predetermined time difference based on the distribution of the amount of angiographic contrast agent administered to the subject to be imaged with respect to time in the brain. The brain tomographic image analysis apparatus according to claim 1, wherein   4. The two tomographic images according to claim 3, wherein one of the two tomographic images is the tomographic image when the abundance is maximized, and the other is the tomographic image before administration of the angiographic contrast agent. Brain tomographic image analyzer. In a brain tomographic image analysis program that causes a computer to execute a process of analyzing a tomographic image of the brain,
An acquisition process of imaging the same tomogram of the brain and acquiring the two tomographic images having a predetermined time difference from each other;
A tomographic image difference process for obtaining a difference in gradation values of pixels of coordinates corresponding to each other between the tomographic images;
Is a brain tomographic image analysis program that runs on a computer.   The brain tomographic image analysis program according to claim 5, wherein the tomographic image is a CT image or an MRI image.   The acquisition processing includes acquiring the two tomographic images having the predetermined time difference based on the distribution of the abundance of the angiographic contrast agent administered to the subject to be imaged with respect to time in the brain. The brain tomographic image analysis program according to claim 5, wherein 8. The tomographic image according to claim 7, wherein one of the two tomographic images is the tomographic image when the abundance is maximum, and the other is the tomographic image before administration of the angiographic contrast agent. Brain tomographic image analysis program.

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