JP4375009B2 - Visceral fat rate diagnostic apparatus and radiation CT apparatus incorporating the apparatus - Google Patents

Description

  The present invention relates to a visceral fat rate diagnostic apparatus that measures a visceral fat ratio using a radiation CT image of a subject, and a radiation CT apparatus (radiation computed tomography apparatus) incorporating the apparatus, and more particularly to a visceral body of a subject. The present invention relates to a technique for accurately measuring fat percentage.

The visceral fat rate is an important index indicating the degree of visceral health. If the visceral fat rate is high, it should be noted. Conventionally, in an apparatus that calculates the visceral fat percentage of a subject based on an X-ray CT image (radiation CT image), as shown in FIG. 6, the X-ray of the subject M displayed on the screen of the image display monitor 51 A visceral fat region of interest ra on the body core side and a subcutaneous fat region of interest rb on the body surface side are set for the CT image Pa, and further, the visceral fat amount qa of the visceral fat region of interest ra and the subcutaneous fat amount qb of the subcutaneous fat region of interest rb. The visceral fat percentage of the subject M is calculated by calculating (qa ÷ qb × 100) after obtaining each using the image signal of the X-ray CT image.
The visceral fat amount qa of the visceral fat region of interest ra and the subcutaneous fat amount qb of the subcutaneous fat region of interest rb are the number of pixels in which the CT value (pixel value) as the pixel signal intensity in each region is regarded as fat. Each is obtained by counting.

However, the above-described conventional apparatus has a problem that the visceral fat rate of the subject cannot be accurately measured by the pseudo fat image that often appears in the X-ray CT image.
For example, if a pseudo fat image in which the CT value is considered to be fat even if it is not visceral fat, such as fat in food present in the stomach or the like, appears in the X-ray CT image, the pseudo fat image is shown in the fat amount. Therefore, the calculated value of visceral fat percentage is distorted only by the pseudo fat image, and the accurate visceral fat percentage cannot be measured.

  The present invention has been made in view of the above circumstances, and is a visceral fat rate diagnostic apparatus capable of accurately measuring the visceral fat rate of a subject even when a pseudo fat image appears in a radiation CT image. An object of the present invention is to provide a radiation CT apparatus.

In order to achieve such an object, the present invention has the following configuration.
That is, the visceral fat percentage diagnostic apparatus according to the first aspect of the present invention includes an image display means for displaying a radiation CT image of a subject that is a measurement target for visceral fat percentage, and a radiation CT displayed by the image display means. Fat rate region of interest setting means for setting a visceral fat region of interest and a subcutaneous fat region of interest in the image, and whether each pixel of the radiation CT image is a fat portion pixel (fat pixel) based on the signal strength of the pixel Determine the visceral fat amount and the subcutaneous fat amount based on the fat pixel determination means, the visceral fat region of interest set by the fat rate region of interest setting means, the subcutaneous fat region of interest, and the fat pixel determined by the fat pixel determination means Visceral fat rate calculating means for calculating the visceral fat rate of the subject, and fat for setting a region (visceral fat rate non-interest region) to be excluded from the visceral fat rate calculation target region in the radiation CT image Have a ratio of non-interest region setting means, the visceral fat region of interest and the visceral fat ratio visceral fat rate calculation means from the visceral fat amount when there is a set of visceral fat rate of non-interest region by the fat percentage of non-interest region setting means pseudo fat is either fat number of pixels belonging also to the non-ROI is subtracted, is the number of fat pixels belonging to any of the similarly subcutaneous fat amount or al subcutaneous fat region of interest and the visceral fat rate region of no interest By subtracting the pseudo fat amount, the visceral fat rate is calculated only from the fat pixels outside the visceral fat rate non-interest region from which the fat pixels within the visceral fat rate non-interest region are removed.

[Operation / Effect] When measuring the visceral fat rate of a subject using the visceral fat rate diagnostic apparatus according to the first aspect of the present invention, the operator first uses the image display means of the subject to be measured for visceral fat rate (for example, the umbilical cord). The radiation CT image (at the position of) is displayed, and then the visceral fat region of interest and the subcutaneous fat region of interest are set in the radiation CT image being displayed by the fat percentage region of interest setting means. Next, after determining whether each pixel of the radiation CT image is a fat portion pixel (fat pixel) by the fat pixel determining means based on the signal intensity of the pixel, the visceral fat rate calculating means calculates the fat. The visceral fat rate of the subject is calculated based on the visceral fat region of interest set by the rate-of-interest setting unit, the subcutaneous fat region of interest, and the fat pixel determined by the fat pixel determining unit.

  In the visceral fat percentage diagnostic apparatus according to the first aspect of the present invention, when a pseudo fat image (for example, a food image in the stomach or intestine) appears in the radiation CT image, the fat percentage non-interest region setting means performs pseudo fat. The entire image is set in the radiation CT image as a region (visceral fat rate non-interest region) excluded from the visceral fat rate calculation target region. Then, the visceral fat rate calculating means calculates the visceral fat rate only from the fat pixels outside the visceral fat rate non-interest area except for the fat pixels in the visceral fat rate non-interest area. As a result, even if a pseudo fat image appears in the radiation CT image, it is possible to avoid the error due to the pseudo fat image being mixed into the fat amount when calculating the fat rate non-interesting visceral fat rate. It is possible to prevent an error caused by the pseudo fat image from being included in the calculated value of the rate.

According to a second aspect of the present invention, in the visceral fat rate diagnostic apparatus according to the first aspect, the fat pixel area is clearly specified in such a manner that the fat pixel area in the radiation CT image can be distinguished from the non-fat pixel area. Means are provided.
is there.

[Operation / Effect] In the visceral fat rate diagnostic apparatus according to the invention of claim 2, when the fat pixel area in the radiation CT image is specified by the fat pixel area specifying means, the fat pixel area can be clearly distinguished from the non-fat pixel area. As a result, the position and shape of the fat pixel area can be clearly grasped, the pseudo fat image appearing in the radiation CT image can be easily found, and the pseudo fat image is set as a visceral fat rate non-interest area without omission. Thus, it is possible to completely avoid the error due to the pseudo fat image being mixed in the fat amount.

Furthermore, in order to achieve the above object, the present invention has the following configuration.
That is, the radiation CT apparatus according to the invention described in claim 3 is a radiation CT apparatus that captures a radiation CT image of a subject that is a target for measuring visceral fat ratio, and the visceral fat ratio according to claim 1 or 2. A diagnostic device is incorporated.

[Operation / Effect] When the visceral fat rate of the subject is measured with the radiation CT apparatus of the invention of claim 3, the radiographic CT image taken after taking the radiographic CT image of the subject as the visceral fat rate measuring object. The visceral fat percentage of the subject is calculated by the visceral fat percentage diagnostic apparatus according to claim 1 or 2 incorporated using

In the case of the visceral fat rate diagnostic apparatus according to the first aspect of the present invention, when a pseudo fat image appears in the radiation CT image of the subject that is the measurement target of the visceral fat rate, the fat rate non-interest region setting means performs the pseudo fat image. By setting the whole as a region to be excluded from the visceral fat rate calculation target region (visceral fat rate non-interesting region) in the radiation CT image, the visceral fat rate calculating means excludes fat pixels in the visceral fat rate non-interesting region. The visceral fat rate is calculated only from fat pixels outside the non-interested region of the visceral fat rate, and it is possible to avoid the error due to the pseudo fat image being mixed in the fat amount when calculating the visceral fat rate. Therefore, the calculated value of the visceral fat rate is an accurate value that does not include an error due to the pseudo fat image.
Therefore, according to the visceral fat rate diagnosis apparatus of the first aspect of the invention, the visceral fat rate of the subject can be accurately measured even when a pseudo fat image appears in the radiation CT image.

In the case of the radiation CT apparatus of the invention of claim 3, the visceral fat rate diagnostic apparatus of claim 1 or 2 is incorporated, and a pseudo fat image appears in a radiation CT image of a subject which is a measurement target of visceral fat rate Even when the visceral fat rate is calculated, it is possible to avoid the fat amount due to the pseudo fat image being mixed in as an error, so that the calculated visceral fat rate does not include an error caused by the pseudo fat image. Value.
Therefore, according to the radiation CT apparatus of the third aspect of the invention, it is possible to accurately measure the visceral fat ratio of the subject even when a pseudo fat image appears in the radiation CT image.

  Embodiments of the apparatus of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a medical X-ray CT apparatus according to an embodiment of the radiation CT apparatus of the present invention in which an example of the visceral fat percentage diagnostic apparatus of the present invention is incorporated.

  As shown in FIG. 1, the X-ray CT apparatus according to the embodiment has a large number of X-ray tubes 1 that irradiate a subject M to be imaged with an X-ray fan beam FB and the extent of the X-ray fan beam FB (for example, (1024) X-ray detectors for transmission X-ray detection, in which X-ray detection elements are arranged in a line, are arranged so as to be rotatable around the subject M while maintaining the opposed arrangement state. A gantry 3 is provided. There is a top plate 3 near the gantry 3, and the subject M is placed on the top plate 3 and reciprocates between the X-ray tube 1 and the X-ray detector 2 in the direction of the body axis Z of the subject M. Moved in and out of gantry 3. With such an X-ray CT apparatus, it is possible to perform planning image acquisition for obtaining a two-dimensional X-ray transmission image for imaging planning and X-ray CT imaging for obtaining an X-ray CT image for diagnosis.

When X-ray CT imaging is performed with the X-ray CT apparatus of the embodiment, usually, planning image imaging is first performed to obtain a two-dimensional X-ray transmission image for imaging planning. Then, after making an imaging plan including setting of an imaging position in the subject M that obtains an X-ray CT image based on a two-dimensional X-ray transmission image for imaging plan planning, X-ray CT imaging is performed, and the subject An X-ray CT image is obtained for a slice cross-section at each imaging position of the subject M that is successively set along the body axis Z direction of M.
Hereinafter, the structure of each part of the X-ray CT apparatus of an Example is demonstrated concretely.

  In the case of planning image capturing, only the top 4 is moved in the direction of the body axis Z of the subject M without rotating the X-ray tube 1 and the X-ray detector 2 with the subject M interposed therebetween. While the subject M is being sent between the X-ray tube 1 and the X-ray detector 2, the X-ray fan beam FB is continuously irradiated from the X-ray tube 1 and at the same time the transmission image output from the X-ray detector 2 is used. A data collection unit (DAS) 5 collects X-ray detection signals. In the planning image capturing, the mechanical control unit 8 controls the movement of the top 4 according to the control of the X-ray transmission imaging control unit 6, and the X-ray exposure control unit 9 controls the X-ray fan beam by the X-ray tube 1. Control FB irradiation.

  In the case of X-ray CT imaging, the top 4 is moved in the direction of the body axis Z of the subject M while the X-ray tube 1 and the X-ray detector 2 are rotated around the subject M with the X-ray tube 1 and the X-ray detector 2 facing each other. While the subject M is being sent between the X-ray tube 1 and the X-ray detector 2, the subject M is continuously irradiated with the X-ray fan beam FB by the X-ray tube 1, and the X-ray fan beam FB An X-ray detection signal for CT image output from the X-ray detector 2 along with irradiation is collected by the data collection unit 5. That is, in the X-ray CT imaging by the embodiment apparatus, the X-ray tube 1 and the X-ray detector 2 collect the CT image X-ray detection signals while relatively moving around the subject M along the spiral path. A helical CT scan is performed. In the X-ray CT imaging, the mechanical control unit 8 controls the rotation of the X-ray tube 1 and the X-ray detector 2 and the movement of the top plate 4 according to the control of the X-ray CT imaging control unit 7, and the X-ray exposure. The controller 9 controls the irradiation of the X-ray fan beam FB by the X-ray tube 1.

  In addition, the position of the top plate 4 that changes with the movement of the top plate 4 is measured with a specific reference position as the origin, fed back to the control system side, and slice slices set as photographing targets in the photographing plan Is set in association with the position of the top 4, and the control of the imaging position is performed by controlling the position of the top 4.

  On the other hand, an image signal processing unit 10 that performs signal processing for two-dimensional X-ray transmission imaging on the X-ray detection signals collected by the data collection unit 5 in the planning image capturing is provided after the data collection unit 5. The image reconstruction unit 11 performs a reconstruction process for X-ray CT imaging on the X-ray detection signals collected by the data collection unit 5 in X-ray CT imaging. Examples of the reconstruction process performed by the image reconstruction unit 11 include a process of performing convolution integration of an X-ray detection signal using an appropriate reconstruction function and then back-projecting the result of convolution integration.

  Further, at the subsequent stage of the image signal processing unit 10 and the image reconstruction unit 11, an image memory unit 12 that stores the captured two-dimensional X-ray transmission image and X-ray CT image, and 2 stored in the image memory unit 12. An image display monitor 13 for displaying a three-dimensional X-ray transmission image, an X-ray CT image, an input operation screen, and the like, an operation console 14 and a mouse (pointing device) 14a for inputting commands and data necessary for imaging Are provided, X-ray transmission imaging control unit 6, X-ray CT imaging control unit 7, mechanical control unit 8, X-ray exposure control unit 9, image signal processing unit 10, image reconstruction unit 11, A host computer 15 is provided for sending commands according to the input operation using the console 14 or the mouse 14a and the progress of photographing so that the image memory unit 12, the image display monitor 13, etc. operate appropriately. To have.

  In addition, the X-ray CT apparatus of the embodiment incorporates a visceral fat rate diagnostic apparatus that measures the visceral fat rate of the subject M, which is an index indicating the degree of visceral health, using the X-ray CT image of the subject M. Yes. When measuring the visceral fat rate of the subject M, an X-ray CT image of the position of the umbilicus of the subject M is usually used, so that the position of the umbilicus of the subject M is imaged when making an X-ray CT imaging plan. To be included in the position.

  That is, the X-ray CT apparatus according to the embodiment is displaying on the image display monitor 13 in addition to the image display monitor (image display means) 13 that displays the X-ray CT image of the subject M that is the measurement target of visceral fat percentage. A fat percentage region of interest setting unit 16 that sets a visceral fat region of interest and a subcutaneous fat region of interest in an X-ray CT image, and whether each pixel of the X-ray CT image is a fat part pixel (fat pixel) A fat pixel determination unit 17 that is determined based on a CT value (pixel value) that is signal intensity, and a visceral fat region of interest, a subcutaneous fat region of interest, and a fat pixel determination unit 17 that are set by the fat rate region-of-interest setting unit 16 A visceral fat rate calculating unit 18 for calculating the visceral fat rate of the subject M based on the fat pixels thus obtained is provided.

  The setting of the visceral fat region of interest and the subcutaneous fat region of interest is performed as follows. First, it is designated that the setting of the visceral fat region of interest is to be executed by operating the console 14 or the mouse 14a, and then the outer edge of the visceral fat region of interest (= subcutaneous fat region of interest) of the X-ray CT image by the operation of the mouse 14a. A pointer (not shown) superimposed on the screen is run along a line that is the inner edge of the screen. At this time, the pointer runs so as to surround the internal organs of the subject M. Then, as shown in FIG. 2, the fat percentage region-of-interest setting unit 16 superimposes and displays the pointer trajectory in the X-ray CT image PA as the outline line LA of the visceral fat region of interest, and in FIG. Thus, the inside of the outline LA is set as the visceral fat region of interest RA.

  Next, after specifying that the setting of the subcutaneous fat region of interest is performed by operating the console 14 or the mouse 14a, the mouse 14a is continuously operated along the line that forms the outer edge of the subcutaneous fat region of interest in the X-ray CT image. Then run the pointer (not shown) superimposed on the screen. At this time, the pointer runs so as to surround the body surface of the subject M. Then, as shown in FIG. 2, the fat rate region-of-interest setting unit 16 superimposes and displays the pointer trajectory as an outline LB of the subcutaneous fat region of interest in the X-ray CT image PA, and also shows a left-upward oblique line in FIG. As described above, the area between the outline line LA and the outline line LB is set as the subcutaneous fat region of interest RB.

The fat pixel determination unit 17 is a threshold range (usually, the pixel signal strength is determined to be fat for each of the pixels in the visceral fat region of interest RA and the subcutaneous fat region of interest RB of the X-ray CT image PA). The CT value is within a range of about −200 to about −50), a pixel whose signal intensity is within a threshold range for determining fat is determined as a fat pixel, and the signal intensity is determined as fat. Pixels that are not within the threshold range for determination are determined as non-fat pixels.
In the device of the embodiment, the threshold range can be changed by operating the console 14 or the mouse 14a.

The visceral fat ratio calculation unit 18 counts all fat pixels in the visceral fat region of interest RA to obtain a visceral fat amount (visceral fat area) QA of the visceral fat region of interest RA, By calculating all the fat pixels and calculating the subcutaneous fat amount (subcutaneous fat area) QB of the subcutaneous fat region of interest RB (QA ÷ QB × 100), the visceral fat percentage of the subject M is calculated. .
In the case of the apparatus of the embodiment, specifically, the visceral fat amount QA is obtained by counting all the fat pixels inside the outline line LA, and after counting all the fat pixels inside the outline line LB, the viscera Subcutaneous fat mass QB is obtained by subtracting fat mass QA.

  However, if a pseudo fat image (for example, a food image in the stomach or intestine) that is not fat but has a pixel CT value within the threshold range for determining fat appears in the X-ray CT image, the fat amount is simulated. An error due to the fat image is added, and the calculated value of the visceral fat rate is changed by the amount corresponding to the pseudo fat image. In the case of the X-ray CT apparatus of the embodiment, even when the pseudo fat image appears in the X-ray CT image. Since it has a characteristic configuration that can prevent the calculated value of the visceral fat rate from being distorted, this point will be specifically described below.

  That is, the X-ray CT apparatus of the embodiment includes a fat rate non-interest region setting unit 19 that sets a region (visceral fat rate non-interest region) to be excluded from the visceral fat rate calculation target region in the X-ray CT image. At the same time, the visceral fat rate calculation unit 18 excludes fat pixels in the visceral fat rate non-interesting region when the visceral fat rate non-interesting region is set by the fat rate non-interesting region setting unit 19. The visceral fat rate is calculated only from fat pixels outside the visceral fat rate non-interest area.

  When setting a visceral fat rate non-interest area in the X-ray CT image, first, the operation of the mouse 14a is performed after specifying the setting of the visceral fat ratio non-interest area by operating the console 14 or the mouse 14a. Then, a pointer (not shown) superimposed on the screen is run along a line that is the outer edge of the visceral fat percentage non-interest area of the X-ray CT image. The pointer runs along the outer edge of the pseudo fat image in the X-ray CT image. Then, as shown in FIG. 2, the fat percentage non-interest area setting unit 19 superimposes and displays the pointer trajectory in the X-ray CT image PA as the outline LC of the visceral fat percentage non-interest area, and obliquely intersects with FIG. As shown by the grid lines, the inside of the contour line LC is set as the visceral fat percentage non-interest region RC. That is, the entire pseudo fat image is set as the visceral fat rate non-interest area RC.

  When the visceral fat rate non-interesting region RC is set by the fat rate non-interesting region setting unit 19, the visceral fat rate calculating unit 18 determines the fat pixels in the visceral fat rate non-interesting region RC as the visceral fat interest region. The pseudo fat masses QCA and QCB are obtained by counting for each RA and subcutaneous fat region of interest RB, and the pseudo fat mass QCA is subtracted from the visceral fat mass QA, and the pseudo fat mass QCB is subtracted from the subcutaneous fat mass QB. Since the pseudo fat image does not appear in the subcutaneous fat region of interest RB and usually appears in the visceral fat region of interest RA, the visceral fat ratio non-interest region RC is usually set only in the visceral fat region of interest RA. The pseudo fat amount QCA has a corresponding value, but the pseudo fat amount QCB is often zero.

In the case of the apparatus of the embodiment, specifically, the pseudo fat amount QCA is obtained by counting all fat pixels in the region surrounded by both the outline line LA and the outline line LC, and the outline line LB and the outline line LC are obtained. It is configured to calculate the pseudo fat amount QCB by subtracting the pseudo fat amount QCA after counting all the fat pixels in the region surrounded by both, wherever the visceral fat rate non-interest region RC is set, The pseudo fat amounts QCA and QCB are accurately obtained.
Therefore, when the visceral fat rate non-interest region RC is set by the fat rate non-interest region setting unit 19, the visceral fat rate calculating unit 18 performs the calculation [(QA−QCA) ÷ (QB−QCB) × 100]. Thus, the visceral fat percentage of the subject M is calculated.

Further, since the X-ray CT apparatus of the embodiment has a configuration for easily finding a pseudo fat image appearing in the X-ray CT image, this point will be specifically described subsequently.
In other words, the X-ray CT apparatus according to the embodiment includes the fat pixel area specifying unit 20 that clearly indicates the fat pixel area in the X-ray CT image in such a manner that it can be distinguished from the non-fat pixel area.
The fat pixel area specifying unit 20 clearly distinguishes the fat pixel area from the non-fat pixel area by highlighting the pixels determined by the fat pixel determining section 17 as fat pixels as shown in FIG. Make it explicit as you can.

As described above, when the fat pixel area can be clearly distinguished from the non-fat pixel area by specifying the fat pixel area in the X-ray CT image by the fat pixel area specifying unit 20, the position and shape of the fat pixel area are determined. Since it can be clearly grasped, a pseudo fat image appearing in the X-ray CT image can be easily found, and the pseudo fat image can be set as the visceral fat rate non-interest region RC without omission.
The fat pixel area specifying unit 20 distinguishes the fat pixel area from the non-fatty pixel area by displaying the pixels determined to be fat pixels in a color that is conspicuous and not highlighted. The configuration may be clearly specified as possible.

  Note that the host computer 15 also operates appropriately in the fat rate region of interest setting unit 16 and the fat pixel determining unit 17, the visceral fat rate calculating unit 18, the fat rate non-interesting region setting unit 19, and the fat pixel area specifying unit 20. In this manner, a command is sent according to the input operation using the console 14 or the mouse 14a and the progress of the measurement process.

  Next, the visceral fat rate measurement process by the X-ray CT apparatus of the embodiment will be specifically described. FIG. 5 is a flowchart showing a visceral fat rate measurement process performed by the example apparatus. Hereinafter, after the subject M is placed on the top 4, the subject M is moved along with the top 4 and set at the X-ray imaging position.

[Step S1] The planning image is captured, a two-dimensional X-ray transmission image for planning the imaging of the subject M on the top 4 is captured and displayed on the screen of the image display monitor 13, and the subject M An imaging plan for X-ray CT images is made in a form that includes the position of the navel as an imaging position.

[Step S2] X-ray CT imaging is executed according to the imaging plan, and an X-ray CT image is obtained and stored in the image memory unit 12.

[Step S3] An operator operates the console 14 or the mouse 14a to select an X-ray CT image at the position of the umbilicus from X-ray CT images stored in the image memory unit 12, and displays it on the screen of the image display monitor 13. indicate.

[Step S4] The operator operates the console 14 or the mouse 14a to set the visceral fat region of interest RA and the subcutaneous fat region of interest RB in the X-ray CT image being displayed on the image display monitor 13.

[Step S5] The operator operates the console 14 or the mouse 14a to cause the fat pixel determination unit 17 to determine fat pixels and non-fat pixels, and to cause the fat pixel region specifying unit 20 to specify fat pixel areas.

[Step S6] The operator looks at the X-ray CT image PB in which the fat pixel area is clearly specified, and visually determines whether or not a pseudo fat image appears. If a pseudo fat image has appeared, the process proceeds to the next step S7. If no pseudo fat image has appeared, the process jumps to step S8.

[Step S7] The operator operates the console 14 or the mouse 14a to set the visceral fat percentage non-interest region RC in such a manner that a pseudo fat image is captured.

[Step S8] The operator operates the console 14 or the mouse 14a to give a command to the visceral fat rate calculator 18 to calculate the visceral fat rate.

[Step S9] When the visceral fat rate non-interest area RC is not set, the process proceeds to the next step S10. When the visceral fat rate non-interest area RC is set, the process jumps to step S11.

[Step S10] The visceral fat percentage calculating unit 18 calculates the visceral fat amount QA of the visceral fat region of interest RA and the subcutaneous fat amount QB of the subcutaneous fat region of interest RB, and then performs a calculation of (QA ÷ QB × 100). Thus, the visceral fat percentage of the subject M is calculated. That is, the visceral fat percentage of the subject M is calculated using the total fat pixels. When the calculation result is displayed or printed, the visceral fat percentage measurement process is completed.

[Step S11] The visceral fat rate calculating unit 18 obtains the visceral fat amount QA of the visceral fat region of interest RA, the subcutaneous fat amount QB of the subcutaneous fat region of interest RB, and the pseudo fat amounts QCA and QCB of the visceral fat rate non-interest region RC, respectively. After that, the calculation of [(QA−QCA) ÷ (QB−QCB) × 100] is further performed to calculate the visceral fat percentage of the subject M. When the calculation result is displayed or printed, the visceral fat percentage measurement process is completed.

As described above, in the apparatus of the embodiment, when a pseudo fat image appears in the X-ray CT image of the subject M that is the measurement target of the visceral fat rate, the fat rate non-interest region setting unit 19 By setting the entire fat image in the X-ray CT image as the visceral fat rate non-interesting region RC, the visceral fat rate calculating unit 18 excludes fat pixels in the visceral fat rate non-interesting region RC, and the visceral fat rate non-interesting region Since it has a configuration for calculating the visceral fat rate only with fat pixels outside RC, it is possible to avoid the error due to the pseudo fat image being mixed in the fat amount when calculating the visceral fat rate. The calculated value is an accurate value that does not include an error caused by the pseudo fat image.
Therefore, according to the apparatus of the embodiment, the visceral fat rate of the subject M can be accurately measured even when a pseudo fat image appears in the X-ray CT image.

In the case of the apparatus of the embodiment, if the fat pixel area can be clearly distinguished from the non-fat pixel area by specifying the fat pixel area in the X-ray CT image by the fat pixel area specifying unit 20, the fat pixel area Since the position and shape of can be clearly grasped, a pseudo fat image appearing in the X-ray CT image can be easily found.
As a result, the pseudo fat image in the X-ray CT image is set as a visceral fat rate non-interest area without omission, and it is possible to completely avoid the error caused by the pseudo fat image in the fat amount.

The present invention is not limited to the above-described embodiment, and can be modified as follows.
(1) In the apparatus of the example, the visceral fat rate was calculated according to the arithmetic expression (QA ÷ QB × 100) to [(QA−QCA) ÷ (QB−QCB) × 100]. The calculation formula for calculating is not limited to that of the embodiment.

(2) In the case of the apparatus of the embodiment, when a pseudo fat image appears in the X-ray CT image of the subject M that is a measurement target of the visceral fat rate, the visceral fat mass QA, the subcutaneous fat mass QB, and the pseudo fat mass After obtaining QCA and QCB, respectively, the pseudo fat mass QCA and QCB were subtracted from the visceral fat mass QA and subcutaneous fat mass QB to obtain (QA-QCA) or (QB-QCB) in the calculation formula. (QA-QCA) or (QB-) in the calculation formula by counting only fat pixels in each region excluding the visceral fat ratio non-interest region RC from the visceral fat region of interest RA or the subcutaneous fat region of interest RB. A configuration in which QCB) is directly obtained may be employed.

(3) In the case of the apparatus of the example, the visceral fat percentage was measured using the X-ray CT image of the position of the umbilicus of the subject M, but the viscera was measured using the X-ray CT image of the position of the subject M other than the umbilicus. The fat percentage may be measured.

(4) In the case of the embodiment, the visceral fat percentage diagnostic apparatus is incorporated in the X-ray CT apparatus, but the visceral fat percentage diagnostic apparatus of the present invention may be in a non-built-in single device form. When the visceral fat percentage diagnostic apparatus is in the form of a single apparatus, the X-ray CT image for measuring visceral fat percentage is an image taken with a separate X-ray CT apparatus.

(5) In the case of the example, the radiation CT image which is the measurement target of the visceral fat rate is an X-ray CT image, and the radiation CT apparatus is an X-ray CT apparatus. Is not limited to an X-ray CT image, and a radiation CT apparatus is not limited to an X-ray CT apparatus.

It is a block diagram which shows the structure of the X-ray CT apparatus which concerns on an Example. It is a front view which shows the X-ray CT image which displayed the outline of the visceral fat region of interest and the subcutaneous fat region of interest set by the visceral fat ratio measurement by the example apparatus in a superimposed manner. It is a front view which shows the X-ray CT image which displayed the visceral fat interested area | region and subcutaneous fat interested area which were set by the visceral fat rate measurement by the Example apparatus virtually superimposed. It is a front view which shows the X-ray CT image in which the area | region of the fat pixel was specified in the Example apparatus. It is a flowchart which shows the visceral fat rate measurement process by the X-ray CT apparatus of an Example. It is a schematic diagram which shows the X-ray CT image used for the measurement of the visceral fat rate by a conventional apparatus.

Explanation of symbols

13 Image display monitor (image display means)
16 ... Fat rate region of interest setting section (Fat rate region of interest setting means)
17. Fat pixel determination unit (fat pixel determination means)
18 ... Visceral fat rate calculation unit (visceral fat rate calculating means)
19 ... Fat rate non-interest region setting unit (Fat rate non-interest region setting means)
20 ... Fat pixel area specifying part (Fat pixel area specifying means)
M: Subject PA, PB: X-ray CT image (radiation CT image)
RA ... Visceral fat region of interest RB ... Subcutaneous fat region of interest RC ... Visceral fat rate non-region of interest

Claims (3)

Image display means for displaying a radiation CT image of a subject to be measured for visceral fat percentage;
A fat percentage region of interest setting means for setting a visceral fat region of interest and a subcutaneous fat region of interest in the radiation CT image displayed by the image display means;
Fat pixel determination means for determining whether each pixel of the radiation CT image is a fat portion pixel (fat pixel) based on the signal strength of the pixel;
Calculate the visceral fat rate of the subject by obtaining the visceral fat amount and the subcutaneous fat amount based on the visceral fat region of interest set by the fat rate region of interest setting means, the subcutaneous fat region of interest and the fat pixel determined by the fat pixel determining unit. Visceral fat percentage calculating means,
A fat rate non-interest region setting means for setting a region (visceral fat rate non-interest region) to be excluded from the calculation target region of the visceral fat rate in the radiation CT image,
When the visceral fat rate non-interesting area is set by the fat rate non-interesting area setting means, the visceral fat rate calculating means calculates the number of fat pixels belonging to both the visceral fat interest area and the visceral fat ratio non-interesting area from the visceral fat amount in a quasi fat mass was subtracted, similarly subcutaneous fat amount or al subcutaneous fat region of interest and the visceral fat rate visceral fat percentage non by subtracting the pseudo fat fatty number of pixels belonging to any of the non-ROI A visceral fat rate diagnostic apparatus that calculates a visceral fat rate only from fat pixels outside a visceral fat rate non-interest region from which fat pixels in a region of interest are removed.   2. The visceral fat rate diagnosis apparatus according to claim 1, further comprising fat pixel area specifying means for clearly indicating fat pixel areas in a radiation CT image in a manner distinguishable from non-fat pixel areas. A radiation CT apparatus for capturing a radiation CT image of a subject which is a measurement target for visceral fat percentage, wherein the visceral fat percentage diagnostic apparatus according to claim 1 or 2 is incorporated.

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