JP2007307125A - Image diagnostic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To support the diagnosis of the presence/absence of neoplasm by imparting a standard uptake value and a CT value and also a new index using them. <P>SOLUTION: On the basis of the distribution images of radioisotopes from a PET for detecting γ rays generated from the radioisotope administered to a subject and obtaining the distribution image of the radioisotope on the basis of the detected γ rays and X-ray tomographic images from an X-ray CT for detecting X rays projected and transmitted through the subject and obtaining the X-ray tomographic images on the basis of the detected X-rays, superimposed images for which both images are superimposed are prepared in an image superimposing means 30. The region of interest is set in a region-of-interest setting means 37 on the basis of the superimposed images. A CT value/SUV ratio which is the ratio of the standard uptake value (SUV) and the CT value in the region of interest is calculated in a CT value/SUV ratio calculation means 33, and the calculated CT value/SUV ratio and the superimposed images are displayed on a display monitor 6. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  According to the present invention, a radioisotope distribution image from PET that detects gamma rays generated from a radioisotope administered to a subject and obtains a radioisotope distribution image based on the detected gamma rays, The present invention relates to an image diagnostic apparatus using an X-ray tomographic image from an X-ray CT that detects X-rays that are projected and transmitted through a specimen and obtains an X-ray tomographic image based on the detected X-rays.

Conventionally, the following is known as a method for acquiring a radioisotope distribution image from PET as described above and an X-ray tomographic image from X-ray CT.
That is, a top plate on which the subject is placed is provided so as to be displaceable in the horizontal direction, and a PET gantry and an X-ray CT gantry are provided on one end side in the moving direction of the top plate.
A gantry for PET is provided with a γ-ray detector, and a control processing unit for PET and a display monitor are provided. As a result, the γ-ray generated from the positron-type radioisotope administered to the subject is detected by the γ-ray detector, and the detected γ-ray detection signal is processed by the control processing unit for PET. A radioisotope distribution image is displayed on a display monitor.

The X-ray CT gantry is provided with an X-ray tube for irradiating the subject with X-rays and an X-ray detector for detecting X-rays transmitted through the subject, and an X-ray CT control processing unit; And a display monitor. As a result, the X-ray detection signal emitted from the X-ray tube, transmitted through the subject and detected by the X-ray detector is processed by the X-ray CT control processing unit, and the acquired X-ray tomographic image is displayed on the display monitor. (Refer to Patent Document 1).
JP 2005-304697 A

  In general, in PET, when a radioisotope distribution image is displayed on a display monitor, the standard uptake rate by PET can also be converted into a pixel value and displayed together. On the other hand, in X-ray CT, when an X-ray tomographic image is displayed on a display monitor, the CT value from the X-ray CT can also be converted into a pixel value and displayed together.

  However, if both the standard intake rate and the CT value are high, it is possible to find a neoplasm when either one of the two values is high. When both were relatively low, there was a problem that there was a high possibility of oversight, such as a false determination that there was no neoplasm even though a neoplasm was found when a close examination was performed.

  The present invention has been made in view of the circumstances as described above, and in addition to the standard ingestion rate and CT value, by giving a new index using them, the diagnosis of the presence or absence of a neoplasm can be assisted. The purpose is to do.

The invention according to claim 1 has the following configuration in order to achieve the above-described object.
That is, a gamma ray generated from a radioisotope administered to a subject is detected, and a radioisotope distribution image from PET that obtains a radioisotope distribution image based on the detected gamma ray, and a subject The projected and transmitted X-rays are detected, and a superimposed image is created by superimposing both images based on the X-ray tomographic image from the X-ray CT that obtains an X-ray tomographic image based on the detected X-ray. An image superimposing means, a region of interest setting means for setting a region of interest based on one of the distribution image, the X-ray tomographic image, or the superimposed image, and a region of interest set by the region of interest setting means A specific correlation value calculating means for calculating a specific correlation value indicating a specific correlation between the standard intake rate by the PET and the CT value by the X-ray CT, and the weight created by the image superimposing means. The image processing apparatus includes a display unit that displays the matching image and the specific correlation value calculated by the specific correlation value calculation unit.

(Operation / Effect) According to the configuration of the diagnostic imaging apparatus of the first aspect of the present invention, a superimposed image obtained by superimposing a radioisotope distribution image and an X-ray tomographic image, a standard uptake rate and an X-ray by PET A specific correlation value indicating a specific correlation with a CT value by CT can be displayed, and a specific correlation value between the standard intake rate and the CT value can be given as a new index.
Therefore, in addition to the standard uptake rate by PET and the CT value by X-ray CT, the presence or absence of a neoplasm can be diagnosed using a specific correlation value that is a new index. Even if there is a high probability that the detection of a neoplasm is likely to be overlooked in individual comparisons of each value, it is possible to find a difference in the comparison between specific correlation values. Can assist in the diagnosis of

The invention according to claim 2 is the diagnostic imaging apparatus according to claim 1,
Pixel value converting means for converting the specific correlation value calculated by the specific correlation value calculating means into a pixel value, and displaying an image of the specific correlation value converted into the pixel value by the pixel value converting means on the display means. Constitute.

(Operation / Effect) According to the configuration of the diagnostic imaging apparatus of the invention according to claim 2, since the specific correlation value for each pixel is converted into a pixel value and displayed as an image, it can be visually determined, Can make it easier to diagnose the presence or absence of organisms.

As described above, according to the configuration of the diagnostic imaging apparatus of the first aspect of the present invention, the superimposed image obtained by superimposing the radioisotope distribution image and the X-ray tomographic image, the standard uptake rate by X and X A specific correlation value indicating a specific correlation with the CT value by line CT can be displayed, and the specific correlation value between the standard intake rate and the CT value can be given as a new index.
Therefore, in addition to the standard ingestion rate by PET and the CT value by X-ray CT, the presence or absence of a neoplasm can be diagnosed using a specific correlation value that is a new index. The values are also relatively low, and even when individual comparisons of each value are likely to miss the discovery of a neoplasm, it is possible to find a difference in the comparison between specific correlation values. Diagnosis of the presence or absence of can be aided.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing an image diagnostic apparatus according to an embodiment of the present invention. A top plate 1 on which a subject M is placed is provided so as to be displaceable in the horizontal direction. A PET gantry 2 and an X-ray CT gantry 3 are provided on one end side.
A PET gantry 2 is provided with a γ-ray detector 4, and a PET control processing unit 5 is provided to form a PET. A display monitor 6 is connected to the PET control processing unit 5. Thereby, γ-rays generated from the positron-type radioisotope administered to the subject M are detected by the γ-ray detector 4, and the detected γ-ray detection signal is processed by the PET control processing unit 5. The acquired radioisotope distribution image is displayed on a display monitor 6 as a display means.

  The X-ray CT gantry 3 is provided with an X-ray tube 7 for irradiating the subject M with X-rays, and an X-ray detector 8 for detecting X-rays transmitted through the subject M, and X-ray CT. Control processing unit 9 is provided to form an X-ray CT, and a display monitor 6 is connected to the X-ray CT control processing unit 9. Thereby, the X-ray detection signal irradiated from the X-ray tube 7 and transmitted through the subject M and detected by the X-ray detector 8 is processed by the X-ray CT control processing unit 9, and the acquired X-ray tomogram is acquired. An image is displayed on the display monitor 6.

  The PET control processing unit 5 includes an RI distribution image acquisition unit 10 that performs image reconstruction based on the γ-ray detection signal output from the γ-ray detector 4 and acquires a radioisotope distribution image, and a subject. RI distribution image photographing position setting unit 11 for setting a photographing position for acquiring a radioisotope distribution image in M, and display of a radioisotope distribution image on the display monitor 6 and a list of acquired radioisotope distribution images An RI distribution image related display unit 12 for performing display is provided.

  Also, the PET control processing unit 5 notifies the X-ray CT control processing unit 9 of the X-ray CT of the imaging position of the X-ray tomographic image set by the RI distribution image imaging position setting unit 11. Radioisotope according to the notification unit 13, the correspondence between the imaging position of the X-ray tomographic image and the imaging position of the distribution image of the radioisotope, and the already-captured position information notified from the already-captured position information notification unit described later And an X-ray imaging execution position information display unit 14 for displaying X-ray imaging execution position information on the display monitor 6 in order to teach the X-ray CT imaging execution position in the distribution image.

  On the other hand, the X-ray CT control processing unit 9 includes an X-ray irradiation control unit 15 that controls X-ray irradiation by the X-ray tube 7 and an image based on an X-ray detection signal output from the X-ray detector 8. An X-ray tomographic image acquisition unit 16 that performs reconstruction and acquires an X-ray tomographic image, and an imaging position for acquiring the X-ray tomographic image in the subject M in correspondence with the imaging position of the radioisotope distribution image An X-ray tomographic imaging position setting unit 17 to be set and an X-ray tomographic image related display unit 18 for displaying the X-ray tomographic image acquired by the X-ray tomographic image acquiring unit 16 are provided.

  The X-ray CT control processing unit 9 includes a designated imaging position information display unit 19 for displaying the designated imaging position information notified from the designated imaging position information notification unit 13 of the PET control processing unit 5 on the display monitor 6. And an already-captured position information notifying unit 20 that notifies the PET control processing unit 9 of the already-captured position information indicating the position at which the X-ray tomographic image is captured.

  The image data of the radioisotope distribution image acquired by the RI distribution image acquisition unit 10 is stored in the PET image memory 21 together with the imaging position information and the standard uptake rate corresponding to the subject M, while the X-ray tomographic image is acquired. The image data of the X-ray tomographic image acquired by the acquisition unit 16 is stored in the X-ray CT image memory 22 together with the imaging position information and the CT value. In the figure, reference numeral 23 denotes a PET operation unit for specifying a radiographic isotope distribution image imaging position, and 24 denotes an X-ray CT operation unit for specifying an X-ray tomographic imaging position. ing.

As shown in the block diagram of the configuration of the first embodiment of the diagnostic imaging apparatus according to the present invention in FIG. 2, the image data stored in the PET image memory 21 and the image stored in the X-ray CT image memory 22 are shown. The data is taken into the microcomputer 25, and a necessary image can be displayed on the display monitor 6.
The microcomputer 25 includes a PET reading unit 26, an X-ray CT reading unit 27, an SUV extracting unit 28, a first pixel value converting unit 29, an image superimposing unit 30, a CT value extracting unit 31, and a second pixel. A value conversion means 32, a CT value / SUV ratio calculation means 33 as a specific correlation value calculation means 33, a third pixel value conversion means 34, and an image output means 35 are provided.
Further, a display image position specifying unit 36 is connected to the microcomputer 25, and a region of interest setting unit 37 is connected to the display monitor 6.

  The PET reading means 26 reads the image data stored in the PET image memory 21 together with the photographing position information and the standard intake rate corresponding to the subject M, and the position specified by the display image position specifying means 36 (subject As shown in the schematic diagram showing an example of the radioisotope distribution image in FIG. 3, the image data of the radioisotope distribution image corresponding to the tomographic position of M) is output. The image can be displayed on one of the divided screens in the display monitor 6 via the image output means 35.

  The X-ray CT reading means 27 reads the image data stored in the X-ray CT image memory 22 together with the imaging position information and the CT value, and the position specified by the display image position specifying means 36 (subject M). Image data of the X-ray tomographic image corresponding to the tomographic position of the X-ray tomographic image), and the X-ray tomographic image is output via the image output means 35 as shown in the schematic diagram showing an example of the X-ray tomographic image of FIG. Thus, it can be displayed on one of the divided screens in the display monitor 6.

  The image superimposing means 30 superimposes the image data of the radioisotope distribution image output from the PET reading means 26 and the image data of the X-ray tomographic image output from the X-ray CT reading means 27, The superimposed image can be displayed on one of the divided screens in the display monitor 6 via the image output means 35, as shown in a schematic diagram showing an example of the superimposed image in FIG.

  The SUV extraction unit 28 extracts a standard intake rate corresponding to the region of interest ROI set by the region of interest setting unit 37 at the position specified by the display image position specifying unit 36 (tomographic imaging position of the subject M). Then, the characters and numerical values are converted into pixel values by the first pixel value conversion means 29, and the characters and numerical values are distributed to the radioisotope of the display monitor 6 via the image output means 35 as shown in FIG. It can be displayed in the upper left corner of the same screen as the image.

  The CT value extraction unit 31 extracts a CT value corresponding to the region of interest ROI set by the region of interest setting unit 37 at the position specified by the display image position specifying unit 36 (tomographic imaging position of the subject M). Then, the characters and numerical values are converted into pixel values by the second pixel value conversion means 32, and the characters and numerical values are converted into the X-ray tomographic image of the display monitor 6 via the image output means 35 as shown in FIG. It can be displayed in the upper left corner of the same screen.

  In the CT value / SUV ratio calculating means 33, based on the standard intake rate extracted by the SUV extracting means 28 and the CT value extracted by the CT value extracting means 31, a specific correlation value indicating a specific correlation between the two is obtained. The CT value / SUV ratio is calculated, the characters and numerical values of the calculated CT value / SUV ratio are converted into pixel values by the third pixel value conversion means 34, and the image output means 35 is used as shown in FIG. Thus, it can be displayed in the upper left corner of the same screen as the superimposed image of the display monitor 6.

Next, an example of calculating the CT value / SUV ratio will be described.
SUV is an abbreviation for Standard Uptake Value, and the relative radioactivity of the tumor, taking into account the measured value (weight and height) of the subject M, the measured value of radioactivity, and the dose of radioisotope. This is a calculated value indicating the uptake of the drug and is defined by the following formula (1).
SUV = tissue radioactivity (Bq / g) / [dosage (Bq) ÷ body weight (g)] (1)

The CT value is a coefficient necessary for reproducing an image by calculation using the fact that the X-ray absorption varies depending on the density of the non-irradiated body, and is defined by the following equation (2). is there.
CT value = K (μ−μw) / μw (2)
Here, μ is an X-ray attenuation coefficient, and μw is an X-ray attenuation coefficient of water. K is a constant of 1000, and is defined by defining the CT value of water as 0 and the CT value of air as -1000.
The CT value / SUV ratio, which is a specific correlation value, is determined by the following equation (3) so that the denominator does not become zero.
CT value / (SUV + α) (3) where 0.1 ≦ α ≦ 0.5
α is a constant set as appropriate.

  With the above configuration, in addition to the radioisotope distribution image displaying the standard uptake rate (SUV) numerically and the X-ray tomographic image displaying the CT value numerically, the CT value / SUV ratio as a specific correlation value is numerically displayed. In addition, a superimposed image of the radioisotope distribution image and the X-ray tomographic image is also displayed on the display monitor 6, and even if it is a neoplasm that is difficult to find by the standard intake rate (SUV) and CT value alone, a specific correlation Using the CT value / SUV ratio, which is a value, as a new index, it is possible to create a case where a close examination can be promoted, and to contribute to enhancing the diagnostic effect.

That is, an example is as shown in Table 1.
Here, CT value / SUV which is a specific correlation value is calculated with α = 0.1. In the case of pattern 1, CT value / SUV = 30 / (6 + 0.1) = 30 / 6.1≈4.92. The same calculation is performed for patterns 2, 3 and 4, and the cases of lung fields.

As explained in the above example, patterns 1 and 2 of the neoplasm in the table have a relatively high CT value compared to the lung field of pattern 5, so the neoplasm can be found in the X-ray tomographic image and can be overlooked The nature is considered low.
In pattern 3, the CT value is not much different from that in the lung field, and it is a faint shadow, but because the standard uptake rate (SUV) is high, a neoplasm can be found in the radioisotope distribution image and the possibility of being overlooked is not It is considered low.
In pattern 4, the CT value is not much different from that in the lung field, and the standard uptake rate (SUV) is also low, so there is a possibility that a neoplasm may be overlooked from the X-ray tomographic image and the radioisotope distribution image. Although relatively high, it is considered that the possibility of avoiding such oversight can be increased by introducing a new index, CT value / SUVn.

FIG. 6 is a block diagram showing the configuration of the first embodiment of the diagnostic imaging apparatus according to the present invention. The differences from the first embodiment are as follows.
In the microcomputer 41, a PET reading means 42, an X-ray CT reading means 43, an SUV extracting means 44, a CT value extracting means 45, a pixel-specific CT value / SUV ratio calculating means 46, a pixel value converting means 47, and Image output means 48 is provided.
The microcomputer 41 is connected to the PET image memory 21, the X-ray CT image memory 22, the display image position specifying means 49, and the display monitor 6.

  The PET reading means 42 reads the image data stored in the PET image memory 21 together with the photographing position information and the standard intake rate corresponding to the subject M, and the position specified by the display image position specifying means 49 (subject Image data of a radioisotope distribution image corresponding to (M tomographic position) is output.

  The X-ray CT reading means 43 reads the image data stored in the X-ray CT image memory 22 together with the imaging position information and the CT value, and the position specified by the display image position specifying means 49 (subject M). Image data of an X-ray tomographic image corresponding to (tomographic tomographic position) is output.

The SUV extraction means 44 extracts and outputs a standard intake rate corresponding to the position designated by the display image position designation means 49 (tomographic imaging position of the subject M).
The CT value extraction means 45 extracts and outputs a CT value corresponding to the position designated by the display image position designation means 49 (the tomographic position of the subject M).

  The pixel-specific CT value / SUV ratio calculation means 46 calculates these values for each pixel based on the standard intake rate (SUV) output from the SUV extraction means 44 and the CT value output from the CT value extraction means 45. (3) is substituted into the equation (α is set to a predetermined value such as 0.1 in the first embodiment), and the CT value / SUV ratio, which is a specific correlation value, is calculated for each pixel.

The pixel value conversion unit 47 converts the CT value / SUV ratio calculated by the pixel-specific CT value / SUV ratio calculation unit 46 into a pixel value that is converted into a gray scale based on the ratio to the maximum change width, and the CT value / SUV. The ratio is imaged and displayed on the display monitor 6 via the image output means 48.
As this display form, various forms such as a display based on a change in shading or a display by color by colorization can be adopted. Other configurations are the same as those of the first embodiment, and the description thereof is omitted.

  According to the second embodiment, the state of change in the CT value / SUV ratio, which is a new index, can be seen at a glance in one image due to differences in lightness and color, improving the ease of diagnosis. it can.

In the above embodiment, the specific correlation value as a new index is
CT value / (SUV + α) (3) where 0.1 ≦ α ≦ 0.5
For example, in order to weight the standard intake rate (SUV), it is multiplied by 1000, and the standard intake rate (SUV) is added to the CT value [CT value + (SUV + α) × 1000]. Or, conversely, to weight the CT value, it is squared to make it CT value × CT value / (SUV + α). In short, even if each of the standard intake rate and CT value is low, a new value Various indicators can be used as long as they have a specific correlation value indicating a specific correlation between the standard intake rate by PET and the CT value by X-ray CT so as to exhibit a different kind of change.

  The present invention is not limited to the case where it is attached to PET, X-ray CT, etc., but an apparatus for reading image data from an FD, CD, MD storing each of a radioisotope distribution image and an X-ray tomographic image, and the above-described microcomputer And a display monitor.

1 is a schematic configuration diagram showing an image diagnostic apparatus according to an embodiment of the present invention. It is a block diagram which shows the structure of Example 1 of the diagnostic imaging apparatus concerning this invention. It is the schematic which shows an example of the distribution image of a radioisotope. It is the schematic which shows an example of an X-ray tomographic image. It is the schematic which shows an example of a superimposed image. It is a block diagram which shows the structure of Example 2 of the diagnostic imaging apparatus concerning this invention.

Explanation of symbols

6. Display monitor (display means)
30 ... Image superposition means 33 ... CT value / SUV ratio calculation means (specific correlation value calculation means)
37 ... Region of interest setting means 47 ... Pixel value conversion means M ... Subject ROI ... Region of interest

Claims (2)

  A radioisotope distribution image from PET that detects γ-rays generated from the radioisotope administered to the subject and obtains a radioisotope distribution image based on the detected γ-ray, and is projected onto the subject Image superposition is performed to detect a transmitted X-ray, and to obtain an X-ray tomographic image based on the detected X-ray, and to create a superimposed image by superimposing both images based on the X-ray tomographic image from the X-ray CT A region of interest setting means, a region of interest setting means for setting a region of interest based on one of the distribution image, the X-ray tomographic image, or the superimposed image; and the region of interest set by the region of interest setting means A specific correlation value calculating means for calculating a specific correlation value indicating a specific correlation between a standard uptake rate by PET and a CT value by the X-ray CT, and a superimposed image created by the image superimposing means An image diagnostic apparatus comprising: a display unit configured to display an image and the specific correlation value calculated by the specific correlation value calculation unit. The diagnostic imaging apparatus according to claim 1,
Pixel value converting means for converting the specific correlation value calculated by the specific correlation value calculating means into a pixel value, and displaying an image of the specific correlation value converted into the pixel value by the pixel value converting means on the display means. A configured diagnostic imaging apparatus.

Images