JP2011062253A - Tomographic image processor, muscle cross-sectional area measurement system, and tomographic image processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tomographic image processor, a muscle cross-sectional area measurement system and a tomographic image processing method, capable of highly accurately calculating a muscle cross-sectional area from a tomographic image of a subject by MRI or CT. <P>SOLUTION: In the muscle cross-sectional area measurement system 1, in the tomographic image processor 20, the area and centroid position of the greater psoas muscle region of a subject are calculated for each tomographic image of the subject captured by an imaging apparatus 10, and the running direction of the greater psoas muscle of the subject is calculated on the basis of the centroid position. Then, in the muscle cross-sectional area calculation unit 25 of the tomographic image processor 20, on the basis of the running direction of the greater psoas muscle and the area of the greater psoas muscle region of the subject in each of the plurality of tomographic images, the area of a part corresponding to the muscle cross-section of the greater psoas muscle of the subject is calculated as the muscle cross-sectional area. Thus, correction according to the physique of the subject and a posture during measurement is performed, and the muscle cross-sectional area is highly accurately calculated in a short time regardless, the posture during the measurement, or the like of the physique of the subject. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a tomographic image processing apparatus, a muscle cross-sectional area measuring system, and a tomographic image processing method.

  It has been pointed out that maintaining a certain muscular strength is important for living independently in an environment where an aging society has come in recent years. In order for an elderly person to maintain a certain muscular strength, it is important to regularly measure the muscular strength, grasp the muscular strength level, and maintain or improve the muscular strength by a method / content suitable for the level. As a method for measuring muscle strength, a method of measuring the strength of a muscle by exerting the maximum muscle strength of the muscle has been used conventionally, but this muscle strength measurement method places a burden on the cardiovascular system and the skeletal muscle system. A person who is likely to be injured by exerting maximum muscle strength, such as a person with a disease, cannot measure muscle strength. Therefore, the maintenance or improvement of muscle strength may not be achieved.

  On the other hand, in recent years, magnetic resonance imaging (Magnetic Resonance) is utilized by utilizing the fact that the maximum force that a muscle (muscle) can exert and the cross-sectional area (muscle cross-sectional area) of the muscle are approximately proportional. By taking a tomographic image of the subject's body by imaging (MRI) or computerized tomography (CT) and calculating the muscle cross-sectional area from the tomographic image, the muscle strength level of the subject can be calculated. Methods for estimating the potential are being studied. Since this muscle strength estimation method estimates muscle strength only by taking a tomographic image by MRI or CT, it does not place a load on the subject unlike conventional muscle strength measurement methods.

  The muscle cross-sectional area used in this muscle strength estimation method refers to a cross-sectional area when the thickest portion of the muscle to be measured is cut in a direction perpendicular to the running direction of the muscle. When accurately calculating the muscle cross-sectional area, the tomographic images of the subject are taken from a plurality of directions to accurately determine the traveling direction of the subject's muscle, It is necessary to capture a tomographic image perpendicular to the traveling direction at a thick position. However, in the method of capturing a tomographic image of a subject from multiple directions, the amount of imaging data required for calculation of the muscle cross-sectional area is large, so the imaging time of the subject is prolonged and the burden on the subject is also large. There is a possibility. Moreover, since the imaging time required per subject becomes long, it becomes difficult to perform imaging of a large number of people with one imaging device.

  On the other hand, generally, a method of roughly estimating a muscle cross-sectional area using conventional MRI or CT that captures a vertical tomographic image for a subject lying on a horizontal bed is often used. In this case, since a tomographic image obtained by conventional MRI or CT imaging is used, the imaging time is shortened. However, since a conventional tomographic image by MRI or CT may not coincide with a muscle cross-section in a direction perpendicular to the running direction of the muscle to be measured, in Non-Patent Document 1, for example, A method is shown in which an average value in the traveling direction is calculated, and an error with the actual muscle cross-sectional area is reduced by correcting the muscle cross-sectional area in the tomographic image of the subject by MRI using the average value. .

McGill, S.M., Santaguida, L., Stevens, J., Measurement of the trunk musculature from T5 to L5 using MRI scansof 15 young males corrected for muscle fiber orientation.Clinical Biomechanics 1993; 8: 171-178

  However, in the method described in Non-Patent Document 1, each physical subject has a different physique, so the error between the muscle cross-sectional area calculated from the tomographic image of the subject and the actual muscle cross-sectional area cannot be sufficiently corrected. There is a case. Even in the same subject, an error may increase due to a difference in posture during imaging. Therefore, it is difficult to measure with high accuracy when it is desired to detect minute changes such as measurement of changes in the muscle cross-sectional area due to training, dieting, supplement intake, and the like.

  The present invention has been made in view of the above, and a tomographic image processing apparatus, a muscle cross-sectional area measuring system, and a muscle cross-sectional area measuring system capable of calculating a muscle cross-sectional area from a tomographic image of a subject by MRI or CT with higher accuracy. An object is to provide a tomographic image processing method.

  In order to achieve the above object, a tomographic image processing apparatus according to the present invention includes an image acquisition means for acquiring a plurality of tomographic images obtained by imaging the psoas major muscle of a subject, and a subject included in the tomographic image. Area calculation means for calculating for each tomographic image the area of the portion corresponding to the psoas major muscle (large psoas muscle region), and for each tomographic image the center of gravity position of the subject's psoas muscle region included in the tomographic image Based on the center of gravity calculated by the center of gravity calculating means, the traveling direction calculating means for calculating the traveling direction of the psoas major, and the traveling direction and area calculating means calculated by the traveling direction calculating means. And a muscle cross-sectional area calculating means for calculating an area of a portion corresponding to the muscle cross section of the psoas major perpendicular to the running direction based on the area of the psoas muscle region calculated for each tomographic image. It is characterized by that.

  According to the tomographic image processing apparatus described above, the area of the psoas muscle region and the center of gravity position of a plurality of tomographic images of the subject are calculated for each image, and the subject's psoas muscle travels based on the center of gravity position. A direction is calculated. Then, based on the running direction of the psoas muscle and the area of the psoas muscle region of the subject for each of a plurality of tomographic images, the area of the portion corresponding to the muscle cross section of the psoas muscle of the subject is calculated. . Thus, in order to determine the traveling direction of the psoas major of the subject based on the tomographic images of the subject and to calculate the muscle cross-sectional area based on the determined traveling direction, the physique of the subject And correction according to the posture at the time of measurement, and the muscle cross-sectional area can be calculated with higher accuracy. Moreover, it is preferable that the tomographic image processing by the above-described tomographic image processing apparatus is applied to the psoas major muscle that is suitable as an evaluation target of the effects of training and rehabilitation. That is, by calculating the muscle cross-sectional area of the large psoas muscle of the subject by the tomographic image processing device, it is possible to appropriately measure a minute change in the psoas major muscle of the subject. Can better grasp the state of muscles.

  Here, as a configuration that effectively exhibits the above-described operation, specifically, the plurality of tomographic images are obtained by imaging cross sections of the psoas muscle parallel to each other, and the traveling direction calculation means includes a plurality of tomographic images. In which the running direction is calculated using the center of gravity position of the psoas muscle of the subject and the imaging position of the tomographic image.

  The muscle cross-sectional area measurement system according to the present invention is a muscle cross-sectional area measurement system including an imaging device and a tomographic image processing device, and the imaging device includes a plurality of psoas major muscles of a subject. The tomographic image processing apparatus includes an image capturing unit configured to capture a tomographic image, and the tomographic image processing apparatus includes: an image acquiring unit configured to acquire a plurality of tomographic images captured by the imaging apparatus; and a subject's psoas muscle region included in the tomographic image. Calculated by area calculation means for calculating the area for each tomographic image, centroid calculation means for calculating the position of the center of gravity of the subject's psoas muscle included in the tomographic image for each tomographic image, and centroid calculation means Based on the center-of-gravity position, a travel direction calculation unit that calculates the travel direction of the psoas major muscle, a travel direction calculated by the travel direction calculation unit, and an area of the psoas muscle region for each tomographic image calculated by the area calculation unit Perpendicular to the direction of travel And Sujidan area calculation means for calculating the area of a portion corresponding to the muscle cross-section of the psoas muscle, characterized in that it comprises a.

  In addition to being described as an invention of a tomographic image processing apparatus as described above, the present invention can also be described as an invention of a tomographic image processing method as follows. This is substantially the same invention only in different categories, and has the same operations and effects.

  That is, the tomographic image processing method according to the present invention is a tomographic image processing method by a tomographic image processing apparatus, in which the tomographic image processing apparatus acquires a plurality of tomographic images obtained by imaging the subject's psoas muscle. The tomographic image includes an acquisition step, an area calculation step in which the tomographic image processing device calculates the area of the psoas major region of the subject included in the tomographic image for each tomographic image, and a tomographic image processing device. A center-of-gravity calculation step for calculating the position of the center of gravity of the psoas muscle region of the subject who is tomographic image, and the tomographic image processing device based on the position of the center of gravity calculated in the center-of-gravity calculation step Based on the travel direction calculated in the travel direction calculation step and the area of the psoas muscle region for each tomographic image calculated in the area calculation step. It characterized in that it and a Sujidan area calculation step of calculating the area of a portion corresponding to the muscle cross-section of the psoas major perpendicular to the direction of travel.

  According to the present invention, a tomographic image processing apparatus, a muscle cross-sectional area measuring system, and a tomographic image processing method capable of calculating a muscle cross-sectional area from imaging data by MRI or CT with higher accuracy are provided.

It is a figure which shows the structure of the muscle cross-sectional area measurement system which concerns on embodiment. It is a figure which shows the structure of the imaging device and tomographic image processing apparatus which concern on embodiment. It is a figure explaining the process for calculating the area of a psoas muscle area from the tomographic image imaged with an imaging device. It is an example of the histogram used when distinguishing the muscle area | region and fat area | region in a tomographic image. It is a figure explaining the outline | summary of the calculation method of the running direction of the psoas major. It is a figure explaining the detail of the calculation method of the running direction of the psoas major. It is a flowchart for demonstrating operation | movement of the muscle cross-sectional area measuring system which concerns on embodiment.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  The muscle cross-sectional area measurement system 1 according to this embodiment includes an imaging device 10 and a tomographic image processing device 20. The imaging device 10 is a device that captures a tomographic image of a subject including the psoas muscle, and the tomographic image captured by the imaging device 10 is sent to the tomographic image processing device 20. The tomographic image processing device 20 is a device that calculates a muscle cross-sectional area of the subject's psoas muscle based on a tomographic image including the subject's psoas muscle.

  The imaging device 10 is a device that images a cross section of a subject, and receives an irradiation device that irradiates the subject with electromagnetic waves such as light rays and X-rays for imaging, and electromagnetic waves from the subject. And a detection device. Specifically, an MRI apparatus, an X-ray CT apparatus, or the like is used as the imaging apparatus 10. Specifically, the MRI apparatus irradiates a subject with a high frequency (RF wave) and observes a nuclear magnetic resonance phenomenon generated in a nucleus in the subject, thereby analyzing anatomical information of a body tissue and blood volume. It is a device that acquires functional information such as. The X-ray CT apparatus is an apparatus that irradiates a subject with X-rays and transmits the subject through the body, and acquires anatomical information of the body tissue from the difference in transmittance. In the imaging apparatus 10 according to the present embodiment, a tomographic image including the psoas major muscle of the subject is taken in order to calculate the muscle cross-sectional area of the psoas major. Note that the psoas major muscle, which is a measurement target of the muscle cross-sectional area by the muscle cross-sectional area measurement system 1 of the present embodiment, is one of the intestinal lumbar muscles, which are muscles connecting the lumbar spine and the femur of the subject. It is a muscle that contributes to flexion of the hip joint and spinal column and stability of the trunk (maintaining posture). In this way, the psoas muscle is a muscle that greatly affects the walking ability and exercise ability of the subject, so the muscle cross-sectional area of the psoas muscle is measured as an index to confirm the effects of training and rehabilitation. And the method of estimating a muscular strength level of a subject from the muscle cross-sectional area of this psoas muscle is used. In addition, the muscle cross-sectional area in the present embodiment refers to a cross-sectional area when the muscle is cut in a direction perpendicular to the running direction of the thickest muscle among the muscles to be measured.

  The tomographic image processing device 20 is imaged by the imaging device 10 and is transmitted from the imaging device 10 via a wired network or the like, based on the tomographic image including the subject's large psoas muscle. Calculate the muscle cross-sectional area. The muscle cross-sectional area of the subject calculated by the tomographic image processing apparatus 20 is output to the subject or the like through a monitor, a printer, or the like. A specific method for calculating the muscle cross-sectional area of the subject in the tomographic image processing apparatus 20 will be described later.

  Next, the configuration of each of the imaging apparatus 10 and the tomographic image processing apparatus 20 will be described with reference to FIGS. 1 and 2. Among these, first, the imaging device 10 will be described. As shown in FIG. 2, the imaging device 10 physically includes a CPU (Central Processing Unit) 10a, a ROM (Read Only Memory) 10b, a RAM (Random Access Memory) 10c, a communication device 10d, a storage device 10e, and the like. These CPU 10a to storage device 10e are connected to a bus 10f. The CPU 10a centrally controls the imaging device 10 by loading a predetermined computer program stored in a built-in memory such as the ROM 10b into the RAM 10c and executing it. The communication device 10d has an interface for communicating with an external device (the tomographic image processing device 20 in the present embodiment). The storage device 10e is a readable / writable memory, and stores various computer programs (particularly, a program for executing processing performed by the imaging device 10 among the processing shown in the flowchart of FIG. 7). The storage device 10e has a database for storing various data necessary for the execution of the computer program, various data obtained by the execution of the computer program (particularly, data relating to imaging of tomographic images of the subject (imaging data)), and the like. Included (not shown in FIG. 2).

  Further, as illustrated in FIG. 1, the imaging device 10 functionally includes an imaging unit 11 (imaging unit) and an imaging data generation unit 12. The imaging unit 11 and the imaging data generation unit 12 execute the above-described computer program stored in the built-in memory of the imaging device 10 such as the ROM 10b by the CPU 10a and operate each component of the imaging device 10 illustrated in FIG. The processing shown in the flowchart of FIG. 7 is executed using the imaging unit 11 and the imaging data generation unit 12.

  The imaging unit 11 has a function of capturing a tomographic image of the subject. When the imaging apparatus 10 is, for example, an MRI apparatus, the imaging unit 11 irradiates a subject placed in a magnetic field by driving the irradiation apparatus and the detection apparatus, and irradiates the subject with high frequency (RF waves). Detects nuclear magnetic resonance phenomena occurring in internal nuclei. Here, in the imaging unit 11, the measurement position of the subject by the imaging unit 11 is specified by applying a gradient magnetic field to the subject, the measurement position specified by the application of the gradient magnetic field, and the measurement position By combining with the nuclear magnetic resonance phenomenon of nuclei at, a cross-sectional image (tomographic image) as if the subject was cut in a specific direction was obtained. To capture a tomographic image of a cross section perpendicular to which direction of the subject (for example, a cross section perpendicular to the body axis direction of the subject) and the number of tomographic images to be captured The parameters are specified in advance by the operator of the imaging apparatus 10 or the like. However, when imaging is performed for the purpose of imaging the abdomen including the psoas major muscle of the subject, generally the body axis direction of the subject is (I.e., to the bed on which the subject lies) a tomographic image (abdominal cross-sectional image) perpendicular to the cross-section and a tomographic image (abdominal forehead image) perpendicular to the longitudinal direction of the subject. Multiple images are taken. The plurality of abdominal cross-sectional images and the plurality of abdominal forehead images are tomographic images parallel to each other for the subject. The tomographic image captured by the imaging unit 11 is sent to the imaging data generation unit 12.

  The number of tomographic images used for calculation of the muscle cross-sectional area in the present embodiment is preferably 5 to 8 in consideration of the burden on the subject related to the tomographic image capturing and the accuracy of the muscle cross-sectional area calculation. . When the number is less than 5, the accuracy of the muscle cross-sectional area calculated by the tomographic image processing apparatus 20 may be lowered. In addition, the accuracy may be improved by using more than eight tomographic images, but the burden on the subject may increase due to an increase in the number of images to be captured. Further, the psoas major muscle, which is a measurement object of the muscle cross-sectional area in the muscle cross-sectional area measurement system 1, has a relatively small angle with the body axis direction of the subject, and therefore, the abdominal cross-sectional image rather than the abdominal frontal frame image. Is preferably used for calculation of the muscle cross-sectional area described later.

  The imaging data generation unit 12 generates imaging data to be transmitted to the tomographic image processing device 20 based on the tomographic image captured by the imaging unit 11. The imaging data here is information in which information specifying the imaging position is associated with the tomographic image captured by the imaging unit 11. The information specifying the imaging position here is, for example, information representing the center position of the tomographic image using three-dimensional coordinates based on the xyz axis. Further, when a plurality of tomographic images are not parallel to each other, information for specifying the imaging direction of the tomographic image can be associated with each tomographic image. In this manner, imaging data in which information specifying the imaging position is associated with the tomographic image is sent from the imaging data generation unit 12 to the tomographic image processing apparatus 20.

  In the following embodiments, the left-right direction of the subject is the x-axis, the front-rear direction of the subject is the y-axis, and the direction in which the body axis of the subject extends is the z-axis. In the calculation of the muscle cross-sectional area in the muscle cross-sectional area measurement system 1, the above-described abdominal cross-sectional image is used as the tomographic image, and the imaging position of the tomographic image and the measurement position (pixel position in the tomographic image) included in the tomographic image are determined. The position information shown is expressed using xyz coordinates. Further, as a plurality of tomographic images, eight tomographic images L1 to L8 obtained by cutting the subject at a plurality of different positions along the z-axis direction (that is, the imaging ranges in the xy-axis direction are the same as each other, A description will be given using a tomographic image of a subject that differs only in the imaging position in the z-axis direction.

  Next, the configuration of each apparatus of the tomographic image processing apparatus 20 will be described with reference to FIGS. 1 and 2. As shown in FIG. 2, the tomographic image processing apparatus 20 physically includes a CPU 20a, a ROM 20b, a RAM 20c, a communication device 20d, a storage device 20e, and the like. These CPU 20a to storage device 20e are connected to a bus 20f. Has been. The CPU 20a centrally controls the tomographic image processing apparatus 20 by loading a predetermined computer program stored in a built-in memory such as the ROM 20b into the RAM 20c and executing it. The communication device 20d has an interface for communicating with an external device (the imaging device 10 in this embodiment). The storage device 20e is a readable / writable memory and stores various computer programs (particularly, a program for executing processing performed by the tomographic image processing device 20 in the processing shown in the flowchart of FIG. 7). . The storage device 20e has a database for storing various data necessary for execution of the computer program and various data obtained by execution of the computer program (imaging data and data generated as a result of processing in the tomographic image processing device 20). Included (not shown in FIG. 2).

  Further, as shown in FIG. 1, the tomographic image processing apparatus 20 functionally has an imaging data acquisition unit 21 (image acquisition unit), an area calculation unit 22 (area calculation unit), and a centroid calculation unit 23 (centroid calculation unit). ), A traveling direction calculation unit 24 (traveling direction calculation unit), a muscle cross-sectional area calculation unit 25 (muscle cross-sectional area calculation unit), and an output unit 26. In the imaging data acquisition unit 21 to the output unit 26, the CPU 20a executes the computer program stored in the internal memory of the tomographic image processing apparatus 20 such as the ROM 20b, and operates each component of the tomographic image processing apparatus 20 shown in FIG. By doing so (using the imaging data acquisition unit 21 to the output unit 26), the processing shown in the flowchart of FIG. 7 is executed.

  The imaging data acquisition unit 21 receives the imaging data of the subject transmitted from the imaging device 10. The information received by the imaging data acquisition unit 21 is stored in the storage device 20e of the tomographic image processing device 20 and sent to the area calculation unit 22. Here, the information specifying the imaging position associated with each tomographic image is also stored in the storage device 20e in association with the tomographic image together with the tomographic image and is also sent to the area calculating unit 22.

  The area calculation unit 22 calculates the area of the large psoas muscle region of the subject in a plurality of tomographic images included in the imaging data stored in the storage device 20e for each tomographic image. The calculation of the area of the large psoas muscle region of the subject in the area calculation unit 22 will be specifically described with reference to FIGS. 3 and 4. In general, in a system aiming at taking a tomographic image of a subject and using the taken image like the muscle cross-sectional area measuring system 1, the data of the cross section is measured based on the DICOM (Digital Imaging and Communication in Medicine) standard. Transmission / reception is performed. The tomographic image used in the area calculation unit 22 (that is, the tomographic image included in the imaging data transmitted from the imaging device 10 and acquired by the imaging data acquisition unit 21) is an image as shown in FIG. It is. In the area calculation unit 22, after the file format is converted from the data format based on the DICOM standard to, for example, the BMP (Bitmap) format, a histogram is generated using luminance information for each pixel included in the tomographic image in the BMP format. Created. An example of this histogram is shown in FIG. In the histogram shown in FIG. 4, there is a low luminance side peak P1 indicating a muscle region and a high luminance side peak P2 indicating a fat region. In the curve obtained by averaging the number of pixels corresponding to each luminance in the histogram for each specific range, the area calculating unit 22 corresponds to a pixel having a luminance higher than a certain threshold (corresponding to an arrow F in FIG. 4). The pixel having the luminance of the region to be determined) is determined as a fat region. The threshold value can be set by, for example, a method in which the luminance on the higher luminance side than the peak P1 corresponding to 50% of the number of pixels of the peak P1 is used as a threshold, or 30 (luminance is 256) for the luminance at which the peak P1 appears. For example, there is a method of using a luminance with added gradation as a threshold value. FIG. 3B is an image in which the fat region F is painted white. Then, in the image shown in FIG. 3B, among the regions that are not painted white as the fat region F, the region provided at the position where it is estimated that the psoas muscle is present is the psoas region M1 (left side in the figure). , M2 (shown on the right side) is shown in FIG. 3C. Then, the area of the psoas muscle region in the tomographic image is calculated by counting the number of pixels in the regions M1 and M2 filled with the image shown in FIG. The area calculation unit 22 calculates the area of the psoas muscle region for each tomographic image by performing the above processing for each of the plurality of tomographic images. The area of the psoas major region calculated here is stored in the storage device 20e in association with each tomographic image. Further, the area value of the psoas muscle region and the position information of the pixels included in the psoas muscle region M1 included in the tomographic image are sent to the centroid calculation unit 23 and the muscle cross-sectional area calculation unit 25.

  The center-of-gravity calculation unit 23 calculates the position of the center of gravity of the subject's psoas muscle region included in the tomographic image for each tomographic image. Specifically, the psoas major regions M1, M2 using the position information (xy coordinates) of each pixel included in the region determined by the center of gravity calculating unit 23 as the psoas major regions M1, M2 by the area calculating unit 22. The position of the center of gravity is calculated. The barycentric positions of the psoas major regions M1 and M2 calculated for each image by the barycentric calculating unit 23 are stored in the storage device 20e in association with each tomographic image and sent to the traveling direction calculating unit 24.

  The traveling direction calculation unit 24 calculates the traveling direction of the psoas muscle based on the position of the center of gravity of the psoas muscle region of the subject calculated by the gravity center calculation unit 23. As shown in FIG. 5, the traveling direction of the large psoas muscle of the subject is the arrangement of the tomographic images of the subject included in the eight tomographic images L1 to L8 along the z-axis according to the imaging position. In the tomographic images L1 to L8, the center of gravity of the psoas muscle obtained by connecting the centers of gravity of the psoas muscle region M1 extends, and the travel direction calculation unit 24 calculates the center of gravity of the psoas muscle. The traveling direction is calculated by obtaining an angle formed by the direction in which the body extends and the body axis direction of the subject.

Specifically, as shown in FIG. 6, the traveling direction calculation unit 24 extracts only the psoas muscle region M1 included in the tomographic images L1 to L8, and corresponds to the three-dimensional coordinate axis of each psoas muscle region M1. (L1a to L8a shown in FIG. 6 indicate the psoas muscle region M1 in each of the tomographic images L1 to L8). Then, the traveling direction calculation unit 24 calculates an approximate straight line that approximates the center of gravity position of L1a to L8a by using the least square method or the like, and the segment K that is divided by the points that touch the L1a and L8a, respectively. Add to the 3D coordinate axes. At this time, the side a in FIG. 6 is a side obtained by projecting the line segment K onto the xy plane, the side b is a side corresponding to the body axis direction of the subject, and the side c is the large waist of the tomographic images L1 to L8. This is a line segment K based on the barycentric positions of the muscle regions L1a to L8a. In addition, the xy coordinates (X ₁ , Y ₁ ) of the point B are the same as the xy coordinates of the end of the line segment K on the L1a side, and the xy coordinates (X ₂ , Y ₂ ) of the point C are the line segment K It is an xy coordinate of the edge part by the side of L8a. Then, using these pieces of information, an angle α formed by the side b and the side c at the vertex A is obtained, and this is set as the running direction of the psoas muscle. Then, the running direction of the contralateral psoas muscle is also calculated by performing the same process as described above for the psoas muscle region M2 of the tomographic images L1 to L8. Thus, the travel direction of the psoas major calculated by the travel direction calculation unit 24 is stored in the storage device 20e in association with a series of tomographic images of the subject and sent to the muscle cross-sectional area calculation unit 25.

  The muscle cross-sectional area calculator 25 is based on the travel direction of the psoas major calculated by the travel direction calculator 24 and the area of the psoas muscle region of the subject for each tomographic image calculated by the area calculator 22. Thus, the area of the muscle cross-sectional area of the psoas major perpendicular to the running direction is calculated. Specifically, since the tomographic images L1 to L8 of the subject imaged by the imaging device 10 were imaged along the body axis direction of the subject (that is, the z axis in FIG. 6), the tomographic images L1 to L8 The psoas muscle regions L1a to L8a are cross sections parallel to the xy plane and are not cross sections perpendicular to the running direction of the psoas muscle. Therefore, the areas of the psoas muscle regions L1a to L8a in the tomographic images L1 to L8 calculated by the area calculation unit 22 are respectively corrected using the angle α indicating the running direction (specifically, the psoas muscle region L1a). By multiplying the area of .about.L8a by cos.alpha.), The area in the cross section perpendicular to the traveling direction is calculated for each tomographic image. The muscle cross-sectional area calculation unit 25 selects the largest area of the corrected psoas muscle region in each of the tomographic images L1 to L8, and this is the muscle cross-sectional area (corrected area, Actually, it is the area of the part corresponding to the muscle cross section of the psoas major). Thus, the area of the portion corresponding to the muscle cross section of the psoas major calculated by the muscle cross-sectional area calculation unit 25 is stored in the storage device 20e in association with a series of tomographic images of the subject and output. Sent to the unit 26.

  The output unit 26 has a function of notifying the examinee, the operator of the tomographic image processing apparatus 20 and the like of the muscle cross-sectional area (corrected area) of the psoas major calculated by the muscle cross-sectional area calculation unit 25. Specifically, for example, the output unit 26 uses the method of displaying on the monitor or the like of the tomographic image processing apparatus 20 or the method of outputting to a printer or the like, and the psoas muscle calculated by the muscle cross-sectional area calculation unit 25. The cross-sectional area (area after correction) is output. At this time, the output unit 26 outputs other information (tomographic image, travel direction of the psoas muscle, etc.) stored in the storage device 20e in association with the calculation result of the area corresponding to the muscle cross section. You can also. Which information is output in what format by the output unit 26 may be set in advance by the operator, or may be changed every measurement.

  Next, the operation of the muscle cross-sectional area measurement system 1 will be described with reference to FIG. First, a tomographic image of a subject is taken by the imaging unit 11 of the imaging device 10 of the muscle cross-sectional area measurement system 1 (S01). The tomographic image of the subject imaged by the imaging unit 11 is transmitted as imaging data to the tomographic image processing device 20 by the imaging data generation unit 12 and received by the imaging data acquisition unit 21 of the tomographic image processing device 20 (image). Acquisition step).

  Next, the area calculation unit 22 calculates the area of the psoas major region of the subject for each image using the tomographic image of the imaging data acquired by the imaging data acquisition unit 21 (S02: area calculation). Step). Next, the barycentric position of the psoas major region is calculated for each tomographic image by the barycentric calculating unit 23 (S03: barycentric calculating step). Next, the travel direction calculation unit 24 calculates the travel direction of the psoas muscle using the information on the center of gravity of the psoas muscle region (S04: travel direction calculation step). Then, based on the area of the psoas muscle region for each tomographic image calculated by the area calculator 22 by the muscle cross-sectional area calculator 25 and the running direction of the psoas muscle calculated by the running direction calculator 24. Then, the area of the part corresponding to the muscle cross section of the psoas major is calculated (S05: muscle cross-sectional area calculating step). Then, the area of the portion corresponding to the muscle cross section calculated by the muscle cross-sectional area calculating unit 25 is output by the output unit 26, so that the examinee or the operator of the tomographic image processing apparatus 20 can obtain the result (the psoas major muscle). It is possible to know the calculation result of the muscle cross-sectional area (S06: output step). By performing the above processing by the muscle cross-sectional area measurement system 1, the muscle cross-sectional area of the large psoas muscle of the subject is calculated.

  Here, the accuracy of the cross-sectional area of the psoas major calculated by the muscle cross-sectional area measurement system 1 will be described with reference to the examples. Table 1 shows the area of the psoas muscle region in the eight abdominal cross-sectional images (tomographic images) obtained by imaging the subject's psoas muscle in a cross section perpendicular to the body axis direction of the subject, Using the image, the travel direction of the psoas muscle is obtained by the method described in this embodiment, and the area of the psoas muscle region of each tomographic image is corrected using this travel direction (the area of the portion corresponding to the muscle cross section). : Area after correction) and the measured value of the cross-sectional area of the psoas major of the subject. Note that the measured value of the cross-sectional area of the patient's psoas muscle is the number of abdominal forehead images and a plurality of abdominal cross-sectional images in the vicinity of the subject's psoas muscle that are taken from these tomographic images. After accurately determining the traveling direction of the examiner's muscle, a tomographic image of a plane perpendicular to the traveling direction of the psoas major is taken at each position where the transverse images 1 to 8 are taken, and from the transverse image The area of the part corresponding to the psoas major is calculated. And the result of having compared the area of the psoas muscle area in a tomographic image, the area after correction | amendment, and an actual measurement value is shown by an area and a percentage. In Table 1, only one of the left and right psoas muscles is shown. Among these eight cross-sectional images, the distance in the xy plane between both ends of the psoas muscle (the length of the side a shown in FIG. 6) is 3.996 cm, and the psoas muscle determined from the eight tomographic images. The traveling direction (the angle α shown in FIG. 6) was 17.84 degrees.

  As shown in Table 1, the running direction of the psoas muscle is obtained by the method described in the present embodiment using the tomographic image of the cross section perpendicular to the body axis direction, and the psoas muscle of each tomographic image is obtained using this running direction. The difference between the corrected area of the area (the area after correction) and the measured value of the cross-sectional area of the psoas major is about ± 1%. It is measured before and after correction (the area of the psoas major in the tomographic image). Compared with the difference of 4-7%, the error is greatly reduced, the area of the psoas muscle can be corrected with high accuracy, and the muscle cross-sectional area can be calculated with high accuracy. It was.

  Then, as described in the present embodiment, the cross-sectional area of the muscle is obtained by determining the running direction of the psoas muscle from the plurality of tomographic images and correcting the area of the psoas muscle region of each tomographic image using this running direction. In the method for calculating the tomographic image, it is not necessary to take a tomographic image of the subject from a plurality of directions as in the case of obtaining an actual measurement value of the muscle cross-sectional area. It was confirmed that a series of processes up to the calculation of the muscle cross-sectional area was performed.

  As described above, according to the muscle cross-sectional area measurement system 1 shown in the present embodiment, the tomographic image processing device 20 captures the area and the center of gravity position of the subject's psoas muscle region by the imaging device 10. The tomographic image is calculated for each of the tomographic images, and the running direction of the subject's psoas muscle is calculated based on the position of the center of gravity of the psoas muscle region. Then, the muscle cross-sectional area calculation unit 25 of the tomographic image processing device 20 determines the large size of the subject based on the traveling direction of the psoas major and the area of the psoas major region of the subject in each of the plurality of tomographic images. The area of the portion corresponding to the muscle cross section of the lower back is calculated. As described above, in the muscle cross-sectional area measurement system 1, the traveling direction of the psoas major of the subject is obtained based on the plurality of tomographic images of the subject, and the subject's traveling direction is determined based on the obtained traveling direction. Since the muscle cross-sectional area of the psoas major is calculated, it is possible to perform correction according to the physique of the subject and the posture at the time of measurement. Therefore, the muscle cross-sectional area can be calculated with high accuracy regardless of the physique of the subject and the posture at the time of measurement. Then, by applying the method for calculating the muscle cross-sectional area by the tomographic image processing by the muscle cross-sectional area measuring system 1 described above to the psoas muscle that is preferably used as an evaluation target of the effect by training and rehabilitation, the subject The minute change of the psoas major muscle can be measured appropriately, and the state of the subject's muscle can be grasped more appropriately.

  Compared with the method of obtaining the measured value of the muscle cross-sectional area by three-dimensionally calculating the running direction of the muscle by capturing tomographic images of the psoas muscle from various directions, the burden on the subject is reduced. Can be reduced. Specifically, it is possible to reduce the influence on the subject due to fatigue of the subject due to long-time imaging, magnetic field (in the case of MRI), or exposure to radiation (in the case of X-ray CT). Further, in the muscle cross-sectional area measurement system 1 of the present embodiment, a tomographic image necessary for calculating the muscle cross-sectional area of the psoas major muscle can be obtained in a short time, so that more subjects are measured. be able to.

  As mentioned above, although embodiment of this invention was described, the muscle cross-sectional area measurement system 1 which concerns on this embodiment can perform a various change. For example, in the above-described embodiment, the case where the imaging device 10 and the tomographic image processing device 20 are separate has been described. However, an apparatus in which these are integrated may be used. In the above-described embodiment, the tomographic image processing apparatus 20 acquires the imaging data when the imaging data including the tomographic image captured by the imaging apparatus 10 is transmitted from the imaging apparatus 10 and received by the tomographic image processing apparatus 20. The configuration has been described. For example, when the operator reads an external file in which information related to a tomographic image of a subject imaged in the past is written into the tomographic image processing apparatus 20, the imaging data acquisition unit 21 captures the imaging data. It can also be set as the aspect acquired. That is, in the present invention, the imaging device 10 is not an essential configuration.

  Further, in the above-described embodiment, the cross-sectional tomographic image perpendicular to the body axis direction of the subject has been described as a plurality of tomographic images obtained by imaging the subject's psoas muscle. The tomographic image of the psoas major can also be imaged using the tomographic image of the above. Even in that case, the angle between the muscle running direction calculated from the barycentric position of the psoas muscle region of the tomographic image and the imaging direction of the tomographic image is calculated, and based on this result, the psoas muscle in the tomographic image is calculated. By correcting the area of the region, the muscle cross-sectional area of the psoas major can be calculated. It is also possible to capture a muscle cross-sectional area using a plurality of tomographic images having different imaging directions of the cross section of the subject. Since it is necessary to correct each tomographic image using information that identifies whether a cross-sectional image is taken, the amount of processing increases even when the muscle cross-sectional area is calculated using mutually parallel tomographic images there's a possibility that.

DESCRIPTION OF SYMBOLS 1 ... Muscle cross-sectional area measurement system, 10 ... Imaging device, 11 ... Imaging part, 12 ... Imaging data generation part, 20 ... Tomographic image processing apparatus, 21 ... Imaging data acquisition part, 22 ... Area calculation part, 23 ... Gravity center calculation part , 24 ... Traveling direction calculation unit, 25 ... Muscle cross-sectional area calculation unit, 26 ... Output unit, L1-L8 ... Tomographic image, L1a-L8a, M1, M2 ... Large psoas muscle region

Claims (4)

Image acquisition means for acquiring a plurality of tomographic images obtained by imaging the psoas major muscle of the subject;
An area calculating means for calculating the area of the psoas major region of the subject included in the tomographic image for each tomographic image;
Centroid calculating means for calculating, for each tomographic image, the centroid position of the psoas major region of the subject contained in the tomographic image;
A traveling direction calculating means for calculating a traveling direction of the psoas major, based on the position of the center of gravity calculated by the gravity center calculating means;
Based on the travel direction calculated by the travel direction calculation means and the area of the psoas muscle region for each tomographic image calculated by the area calculation means, the psoas major perpendicular to the travel direction Muscle cross-sectional area calculating means for calculating the area of the portion corresponding to the muscle cross-section,
A tomographic image processing apparatus comprising: The plurality of tomographic images are obtained by imaging cross sections of the psoas major parallel to each other,
The travel direction calculation means calculates the travel direction using a center of gravity position of the psoas major region of the subject in the plurality of tomographic images and an imaging position of the tomographic image. The tomographic image processing apparatus described. A muscle cross-sectional area measuring system including an imaging device and a tomographic image processing device,
The imaging device
Comprising imaging means for imaging a plurality of tomographic images of the psoas major of the subject;
The tomographic image processing apparatus comprises:
Image acquisition means for acquiring the plurality of tomographic images captured by the imaging device;
An area calculating means for calculating the area of the psoas major region of the subject included in the tomographic image for each tomographic image;
Centroid calculating means for calculating, for each tomographic image, the centroid position of the psoas major region of the subject contained in the tomographic image;
A traveling direction calculating means for calculating a traveling direction of the psoas major, based on the position of the center of gravity calculated by the gravity center calculating means;
Based on the travel direction calculated by the travel direction calculation means and the area of the psoas muscle region for each tomographic image calculated by the area calculation means, the psoas major perpendicular to the travel direction Muscle cross-sectional area calculating means for calculating the area of the portion corresponding to the muscle cross-section,
A muscle cross-sectional area measurement system comprising: A tomographic image processing method using a tomographic image processing apparatus,
The tomographic image processing apparatus obtains a plurality of tomographic images in which the subject's psoas major is imaged; and
An area calculating step in which the tomographic image processing apparatus calculates an area of the psoas major region of the subject included in the tomographic image for each tomographic image;
A center-of-gravity calculation step in which the tomographic image processing apparatus calculates a center-of-gravity position of the psoas major region of the subject included in the tomographic image for each tomographic image;
The tomographic image processing apparatus calculates a traveling direction of the psoas muscle based on the center of gravity position calculated in the center of gravity calculating step;
The tomographic image processing apparatus is configured for the traveling direction based on the traveling direction calculated in the traveling direction calculating step and the area of the psoas muscle region for each tomographic image calculated in the area calculating step. A muscle cross-sectional area calculating step for calculating an area of a portion corresponding to a muscle cross-section of the psoas major perpendicular to
A tomographic image processing method comprising: