JP2016202208A - Ultrasonic diagnostic system - Google Patents

Abstract

An improved technique for measuring information serving as an index of visceral fat in a relatively simple manner and with a relatively high accuracy is provided. A tomographic image in the abdomen of a subject is formed based on a reception signal obtained by transmitting and receiving ultrasonic waves. On the tomographic image, the distance Δa from the body surface near the umbilicus of the subject to the visceral region contour is measured as the subcutaneous fat thickness. Apart from this ultrasonic measurement, the entire abdominal longitudinal thickness (length A), which is the thickness of the entire abdomen of the subject in the front-rear direction, is measured. Then, in the process of deriving the index value of the visceral fat in the visceral region by approximating the cross section of the entire abdomen with the ellipse 52, the entire abdominal longitudinal thickness and subcutaneous fat thickness are input, and the index value of the visceral fat of the subject is Derived. [Selection] Figure 4

Description

  The present invention relates to an ultrasonic diagnostic system, and more particularly, to an ultrasonic diagnostic system that obtains information serving as an index of visceral fat.

  Ultrasound diagnostic systems using ultrasound are widely used in the medical field. The ultrasonic diagnostic system is configured by, for example, a single ultrasonic diagnostic apparatus or a combination of an ultrasonic diagnostic apparatus and another apparatus (including a computer).

  According to ultrasonic diagnosis, for example, exposure that occurs in X-ray diagnosis can be avoided, and a large-scale mechanism required for X-ray diagnosis is unnecessary. From such convenience, it is desired to use ultrasonic diagnosis for, for example, medical examination of metabolic syndrome (visceral fat type obesity).

  For example, Patent Document 1 discloses a technique for obtaining information serving as an index of visceral fat by ultrasonic diagnosis. The ultrasonic diagnostic system disclosed in Patent Document 1 is an epoch-making device that can easily and accurately measure information representing visceral fat mass, and has an extremely high practical utility value in, for example, a medical checkup of metabolic syndrome. There is expected.

Japanese Patent No. 5368615

  In view of the background art described above, the inventor of the present application has repeatedly researched and developed an ultrasonic diagnostic system for obtaining information serving as an index of visceral fat. In particular, we focused on further improvements of the groundbreaking invention disclosed in Patent Document 1.

  The present invention has been made in the course of its research and development, and its purpose is to provide an improved technique for measuring information serving as an index of visceral fat in a relatively simple and relatively high accuracy. is there.

  An ultrasonic diagnostic system suitable as a specific example of the present invention includes an image forming unit that forms an ultrasonic image in an abdomen of a subject based on a reception signal obtained by transmitting and receiving ultrasonic waves, and the ultrasonic wave On the image, a measurement unit that measures the distance from the body surface near the umbilicus of the subject to the visceral region contour as subcutaneous fat thickness, and the entire thickness of the abdomen that is the longitudinal thickness of the entire abdomen of the subject In the process of deriving the index value of the visceral fat in the visceral region by approximating the cross section of the entire abdomen with an elliptical shape and obtaining the measurement data of the abdomen, And an index value deriving unit that obtains an index value of the visceral fat of the subject as an output value of the process.

  In the above configuration, for example, the transmission / reception surface of an ultrasonic probe (ultrasonic probe) is applied to the surface of the subject's abdomen, and preferably ultrasonic waves are transmitted and received from the body surface near the subject's navel to the abdomen. Is done. An ultrasonic image in the abdomen of the subject is formed on the basis of the received signal thus obtained. As the ultrasound image, a tomographic image in the abdomen of the subject is suitable, but an image other than the tomographic image, such as a one-dimensional or three-dimensional ultrasound image, may be used as long as measurement that can be regarded as subcutaneous fat thickness is possible. It may be used. As the tomographic image, an image representing a cross section of the abdomen of the subject is suitable, but an image representing a longitudinal section of the abdomen of the subject may be used.

  In the above configuration, the measurement unit measures a distance corresponding to the subcutaneous fat thickness based on input information from a user (inspector) who visually observes the ultrasonic image or by image analysis processing related to the ultrasonic image. To do. In the former case, for example, a marker for supporting user operation is displayed on the ultrasound image, and the user determines the position of the marker, whereby the distance measurement point, that is, the position of the body surface near the umbilicus of the subject and the internal organs. The position of the region contour is determined. In the latter case, for example, at least one of the position of the body surface in the vicinity of the umbilicus of the subject and the position of the visceral region contour is an image analysis process related to an ultrasound image (a process related to known surface detection or a process related to contour detection). Is included).

  In general, the structure of the subject's abdomen can be broadly divided into the muscle layers such as the abdominal muscles and back muscles around the visceral regions containing visceral tissue and visceral fat, and the subcutaneous fat region is also surrounded by the muscle layer. is there.

  In measuring the distance from the body surface of the subject to the visceral region contour, it is desirable that the measurement points of the visceral region contour are set at the outer edge of the visceral region. For example, in a portion where the visceral region and the muscle layer are in contact with each other, it is desirable to use the boundary between the visceral region and the muscle layer as a measurement point. However, since the muscle layer has a relatively large thickness for each part, if the boundary between the visceral region and the muscle layer is used as a measurement point, the position of the measurement point varies due to the influence of the muscle layer having a different thickness for each part. The measurement value (measured distance) also varies.

  Therefore, in the above configuration, the measurement unit measures the distance from the body surface near the umbilicus of the subject to the visceral region contour. In the vicinity of the umbilicus, there is a portion where the muscle layer is thin (it can be considered that there is no muscle layer), and variations in measured values due to the thickness of the muscle layer can be reduced or avoided. In a portion where the muscle layer is thin (it can be regarded that there is no muscle layer), the distance from the body surface to the visceral region contour can be regarded as the thickness of the subcutaneous fat region, that is, the subcutaneous fat thickness.

  Moreover, in the said structure, the measurement data of the abdomen whole body vertical thickness which is the thickness of the front-back direction of the whole abdomen of a subject are utilized. Information on the size of the entire abdomen is difficult to measure with only a normal ultrasonic probe provided in a general ultrasonic diagnostic apparatus. Therefore, it is desirable to obtain measurement data of the entire abdomen vertical thickness from, for example, a non-contact type measuring instrument such as a laser or an ultrasonic sensor. If it is a non-contact type, the measurement error by crushing the body surface of a subject can be avoided. As long as the measurement error can be avoided or reduced, a contact-type measuring instrument such as a caliper-like measuring instrument may be used.

  The index value deriving unit having the above configuration executes a process of deriving an index value of the visceral fat in the visceral region by approximating the cross section of the entire abdomen with an elliptical shape. The cross section (transverse section) of the entire abdomen has a certain validity in approximation by an elliptical shape from an empirical or anatomical viewpoint. The elliptical shape naturally includes the shape of an elliptical function defined mathematically, but may be an elliptical shape obtained by correcting the elliptical function to such an extent that it can be substantially regarded as an elliptical shape. . Then, the index value deriving unit obtains the index value of the visceral fat of the subject as the input value of the above process using the entire abdominal longitudinal thickness and subcutaneous fat thickness as the output value of the above process.

  When the cross section of the entire abdomen is approximated by an elliptical shape, it is desirable to adapt the elliptical shape to the shape of the entire abdomen of the subject to be measured. Therefore, the size of the elliptical vertical direction (front-rear direction of the subject) is adjusted in accordance with the overall thickness of the abdomen of the subject to be measured. For example, the size of the ellipse in the vertical direction, that is, the axial length (short axis diameter) in the vertical direction is defined as the overall thickness of the abdomen. In this case, the longitudinal radius of the ellipse (short axis radius of the ellipse) is half (1/2) of the longitudinal thickness of the entire abdomen. Of course, a value obtained by correcting half of the overall thickness of the abdomen may be used as the minor axis radius of the ellipse. In addition, when approximating the cross section of the entire abdomen with an elliptical shape, the horizontal size of the elliptical shape (the horizontal direction of the subject) is adapted to the thickness of the entire abdomen of the subject to be measured. It is desirable to make it. Therefore, for example, the total thickness of the abdomen, which is the thickness of the entire abdomen of the subject, is measured, and the horizontal size of the ellipse, that is, the axial length (major axis diameter) in the horizontal direction is measured. It is good. Note that a correlation between the abdominal overall vertical thickness and the abdominal overall horizontal thickness may be obtained in advance, and the abdominal overall horizontal thickness may be estimated from the measurement data of the abdominal overall vertical thickness based on the correlation. If the cross section of the entire abdomen of the subject (for example, the cross section) can be approximated by an elliptical shape, that is, if the elliptical shape can be adapted to the cross section of the entire abdomen of the subject, based on the elliptical shape, For example, the entire abdominal area of the subject (cross-sectional area of the entire abdomen) can be estimated. These estimates also have some validity from an empirical or anatomical point of view.

  Further, the index value deriving unit configured as described above approximates the cross section of the entire abdomen in an elliptical shape and executes the process of deriving the index value of the visceral fat in the visceral region, in addition to the vertical thickness of the entire abdomen, the subcutaneous fat thickness Is the input value of the process. Subcutaneous fat thickness has a relatively strong correlation with the area of the subcutaneous fat region (subcutaneous fat area) from an empirical or anatomical viewpoint. Therefore, the subcutaneous fat area can be estimated from the subcutaneous fat thickness based on the correlation. Furthermore, from a empirical or anatomical point of view, there is a relatively strong correlation between the difference area obtained by removing the subcutaneous fat area from the entire abdominal area and the visceral area (area within the visceral area). ing. Therefore, the index value deriving unit derives, for example, the visceral area of the subject by the above processing using the entire abdominal longitudinal thickness and subcutaneous fat thickness as input values. The derived visceral region area may be used as an index value for visceral fat, or another index value may be calculated based on the visceral region area. As another index value, a visceral fat amount in which a strong correlation with the visceral region area is recognized is preferable. For example, a numerical value indicating the visceral fat amount itself may be used as the index value, and a value indicating the magnitude of the visceral fat amount may be used as the index value.

  In calculating the visceral area, the index value deriving unit subtracts the subcutaneous fat thickness from the short axis radius of the ellipse obtained from the vertical thickness of the entire abdomen, that is, the short axis radius of the entire abdomen and the short axis radius of the entire abdomen. The short axis radius of the visceral region obtained in this way is calculated, and the visceral region area is obtained by removing the subcutaneous fat area from the entire abdominal area based on the ratio of the short axis radius of the entire abdomen and the short axis radius of the visceral region. May be.

  In a desirable specific example, the index value deriving unit is based on the subcutaneous fat thickness from the entire abdominal area obtained by adapting an elliptical shape to a cross section of the entire abdomen of the subject according to the entire abdomen vertical thickness. The visceral region area is calculated by removing the subcutaneous fat area, and at least one of the visceral fat area estimated from the visceral region area and the visceral region area is derived as the index value.

  In a desirable specific example, the data acquisition unit includes measurement data of the entire abdominal width that is the thickness of the entire abdomen of the subject in the left-right direction, or the entire abdomen of the subject. The index value deriving unit adapts the elliptical shape to the cross section of the entire abdomen of the subject according to the overall thickness of the abdomen and the overall thickness of the abdomen or the circumference of the abdomen. It is characterized by that.

  In a preferred embodiment, the image forming unit forms a tomographic image in the abdomen of the subject as the ultrasound image, and the ultrasound diagnostic system causes the tomography to originate from the subject's umbilicus. It further has a display processing unit for forming, in the tomographic image, a measurement marker having a predetermined positional relationship with respect to the position of a band-like or divergent shadow region generated in the image.

  In a preferred embodiment, the display processing unit forms a reference marker to be aligned with the shadow region in the tomographic image.

  In a preferred embodiment, the display processing unit forms a line-shaped reference marker and a line-shaped measurement marker having a predetermined interval with respect to the reference marker in the tomographic image, and is generated in the tomographic image. The subcutaneous fat thickness is measured on the measurement marker in a state where the reference marker is aligned in a shadow region.

  In a preferred embodiment, the ultrasonic diagnostic system measures the entire thickness of the abdomen in a non-contact manner with respect to the body surface of the subject at a measurement position based on the position of the umbilicus of the subject. It further has a vessel.

  In a preferred embodiment, the ultrasonic diagnostic system includes a plurality of individual parameters related to the subject, and the index value of the subject using a plurality of parameters that satisfy a condition indicating that the correlation is weak. It further has a correction part which corrects.

  In a preferred embodiment, the plurality of parameters satisfying the condition include gender, age, and height of the subject.

  Further, an information processing apparatus suitable as a specific example of the present invention is a visceral region from the body surface in the vicinity of the subject's umbilicus on an ultrasound image in the abdomen of the subject obtained by transmitting and receiving ultrasound. A measurement unit that measures the distance to the contour as subcutaneous fat thickness, a data acquisition unit that obtains measurement data of the entire thickness of the abdomen, which is the thickness of the entire abdomen of the subject, and an elliptical cross section of the entire abdomen In the process of deriving an index value of the visceral fat in the visceral region by approximating the shape, the abdomen overall vertical thickness and the subcutaneous fat thickness are used as input values for the process, and the viscera of the subject as output values of the process An index value deriving unit for obtaining an index value of fat.

  The information processing apparatus can be realized by a computer (including a tablet terminal), for example. Specifically, the distance from the body surface near the umbilicus of the subject to the visceral region contour is measured as the subcutaneous fat thickness on the ultrasound image in the abdomen of the subject obtained by sending and receiving ultrasound. A function to obtain measurement data of the entire thickness of the abdomen, which is the thickness of the entire abdomen of the subject, and an index of the visceral fat in the visceral region by approximating the cross section of the entire abdomen in an elliptical shape In the process of deriving a value, the computer realizes a function of obtaining the index value of the visceral fat of the subject as an output value of the process using the abdominal overall vertical thickness and the subcutaneous fat thickness as input values of the process A program can cause a computer to function as the information processing apparatus. The program may be stored in a computer-readable storage medium such as a disk or a memory and provided to the computer via the storage medium, or may be provided via a telecommunication line such as the Internet. May be provided.

  The present invention provides an improved technique for measuring information serving as an index of visceral fat relatively easily and with relatively high accuracy.

It is a figure which shows the positional relationship of an abdominal part and a probe. It is a figure which shows the relationship between an abdominal section and a tomographic image. It is a figure which shows the modification of the contact state of a probe. It is a figure for demonstrating the calculation principle which derives | leads-out the index value of a visceral fat. 1 is an overall configuration diagram of an ultrasonic diagnostic system suitable for implementing the present invention. It is a figure for demonstrating the calculation of an index value. It is a figure for demonstrating the position of ultrasonic measurement. It is a figure which shows the specific example 1 of the marker displayed as a guide of ultrasonic measurement. It is a figure which shows the specific example 2 of the marker displayed as a guide of ultrasonic measurement.

  FIG. 1 is a diagram showing a positional relationship between an abdomen and a probe, and FIG. 1 schematically shows a cross section of the abdomen in a living body. In FIG. 1, the situation at the time of measuring the index value representing the visceral fat mass is shown. Incidentally, the X direction is the backbone direction, the Z direction is the front-rear direction of the living body, and the Y direction is the left-right direction of the living body. FIG. 1 shows a cross section when viewed from the foot side to the head side.

  In FIG. 1, the living body 10 is the abdomen, the lower side is the back, and the upper side is the abdominal surface 12. For example, the living body 10 is placed on its back on a bed. A subcutaneous fat layer (subcutaneous fat region) 14 exists inside the living body 10. The subcutaneous fat layer 14 is a layer including skin. The muscle layer 16 exists inside thereof, and the visceral fat-containing region (visceral region) 20 exists further inside thereof. The visceral fat-containing region 20 is originally a three-dimensional region, but is shown as a two-dimensional region extending on the YZ plane in FIG. 1 and includes a plurality of organs. In the visceral fat-containing region 20, visceral fat is present in gaps other than organs and bones.

  In FIG. 1, the code | symbol 18 represents the lumbar vertebrae, and the code | symbol 24 represents the organ. In the abdomen 10, there is an abdominal aorta (lower aorta) 22 particularly in the visceral fat-containing region 20, which is a thick artery, and its pulsation can be easily visually recognized on an ultrasound image. The abdominal aorta 22 is located substantially at the center on the cross section of the abdomen 10. The outer edge of the visceral fat-containing region 20 is the inner surface of the muscle layer 16, which is indicated by reference numeral 16A.

  When measuring the index value, the probe 36 is brought into contact with the body surface (abdominal surface) 12 of the abdomen. Specifically, in the vicinity of the umbilicus position 38, for example, the probe 36 is brought into contact with a position 40 shifted from the umbilicus position 38 to the subject's left hand side by a predetermined distance (for example, a distance shorter than 2 to 3 cm). The Specifically, as will be described in detail later, the probe 36 is brought into contact with a position 40 away from the navel having an air layer and as close to the navel as possible in a vertical posture.

  An ultrasonic beam is scanned by the probe 36 to form a two-dimensional scanning surface 42. In the example of FIG. 1, the scanning plane 42 forms a YZ plane, that is, corresponds to a cross section. As will be described later, it is also possible to bring the probe 36 into contact so that the scanning surface has a longitudinal section. If the probe 36 is pushed too far, the distance measurement value will fluctuate. Therefore, as long as the wave transmitting / receiving surface of the probe 36 is in close contact with the body surface, the probe 36 is in contact with the body surface with an appropriate contact pressure. The

  FIG. 2 shows the positional relationship between the abdomen 10 and the tomographic image 44. A tissue on the scanning plane appears in the tomographic image 44. Tissue that exists outside the scan plane is not imaged. In ultrasonic measurement, particularly ultrasonic measurement by one probe contact, it is almost difficult to image the entire abdomen 10. The same is true even if the probe contact is performed a plurality of times. In the present embodiment, the size of the entire abdomen is separately measured, and a measurement value (measurement data) relating to the size of the entire abdomen is also used for calculating the index value. That is, information indicating the size or spread of the entire abdomen (information difficult to obtain by ultrasonic diagnosis) is actively used.

  On the tomographic image 44 displayed on the screen, the distance Δa from the body surface of the abdomen near the navel of the subject (living body 10) to the visceral region contour is measured. In the measurement, a first marker corresponding to the body surface of the abdomen and a second marker corresponding to the contour of the visceral fat-containing region (visceral region contour) are displayed, and the first marker and the second marker are displayed on the tomographic image 44. When the user (inspector) designates the position of the distance, the distance measurement points (two points) are determined. In FIG. 2, the code | symbol 48 has shown the measurement point of the abdominal surface, and the code | symbol 50 has shown the measurement point of the outline (visceral area outline) of a visceral fat containing area | region.

  In the example of FIG. 2, the measurement path connecting two measurement points corresponds to the scanning plane center line, but the measurement path may be inclined with respect to the scanning plane center line. Various measurement techniques can be applied as long as the distance between the two measurement points can be accurately measured.

  In addition, as shown in FIG. 3, the probe 36 may be positioned so that the scanning surface 42 has a vertical cross section to form an image. Also in this case, it is possible to specify the measurement point 48A corresponding to the body surface of the abdomen and the measurement point 50A corresponding to the visceral region contour in the image, and the distance Δa between the two measurement points is measured on the image. it can. In either of the transverse section (FIG. 2) and the longitudinal section (FIG. 3), the probe 36 may be brought into contact with a position 40 that avoids the navel having an air layer and is as close to the navel as possible. desirable.

  FIG. 4 is a diagram for explaining a calculation principle for deriving an index value of visceral fat. FIG. 4 shows an elliptical approximation model that approximates the cross section of the entire abdomen in an elliptical shape. An ellipse 52 has a shape approximating the outer shape of the abdominal section. From an anatomical point of view and as a rule of thumb, such approximations have a certain validity. Reference numeral 46B denotes the center of the ellipse 52, the minor axis diameter A and minor axis radius a (length a = A / 2) of the ellipse 52, and the major axis diameter B and major axis radius b (length b = length) of the ellipse 52. B / 2) is illustrated.

  The size and shape of the ellipse 52 are set according to the shape of the entire abdomen of the subject to be measured. In the ellipse approximation model shown in FIG. 4, the minor axis direction of the ellipse 52 is the front-rear direction (vertical direction) of the subject, and the major axis direction of the ellipse 52 is the left-right direction (lateral direction) of the subject. Therefore, the minor axis diameter A of the ellipse 52 is set to be the entire abdominal longitudinal thickness which is the thickness of the entire abdomen of the subject, and the major axis diameter B of the ellipse 52 is set to the abdomen of the subject. It is set to be the entire abdominal width that is the thickness in the entire horizontal direction.

  In the present embodiment, the abdomen overall vertical thickness and abdominal overall horizontal thickness of the subject are measured by a measuring instrument described later, and the short axis diameter A and the length of the ellipse 52 are measured according to these measurement values (measurement data). The length of the shaft diameter B is set. Instead of the overall thickness of the abdomen of the subject, the abdomen circumference of the subject may be measured, and the ellipse 52 may be determined so that the circumference c of the ellipse 52 becomes the abdomen circumference. Compared to the circumference of the abdomen, the overall thickness of the abdomen is less likely to be affected by the breathing of the subject.

  Even when the ellipse 52 does not completely match the actual abdominal outline of the subject, measurement is performed with the error in the ellipse approximation suppressed by applying correction conditions described later or by applying a calculation formula that takes various parameter values into consideration. The accuracy can be improved.

  Incidentally, when the shape and size of the ellipse 52 are adapted to the shape of the entire abdomen of the subject, the center 46B of the ellipse 52 is approximately the position of the abdominal aorta 22 (FIG. 1). That is, the distance from the abdominal surface to the abdominal aorta 22 (for example, the center thereof) substantially matches the short axis radius a, and can be approximated as half (1/2) of the entire abdominal longitudinal thickness (short axis diameter A). . This approximation also has a certain validity from an anatomical point of view and as a rule of thumb.

The area S0 of the ellipse having the minor axis radius a (a = A / 2) and the minor axis radius b (b = B / 2) is expressed as follows, and the ellipse circumference c is approximately expressed as follows. (Other approximations can be used).
S0 = πab (1)
c = π × (2 (a ² + b ² )) ^1/2 − (ab) ² /2.2 (2)

Since the abdomen is an ellipse close to a circle, in Equation (2), the second term is negligibly smaller than the first term on the right side, and the major axis radius b can be expressed approximately as follows.
b = (c ² / 2π ² −a ² ) ^1/2 (3)

From the formulas (1) and (3), the total area S0 is expressed as follows.
S0 = πa (c ² / 2π ² -a ² ) ^1/2 (4)

  In other words, the entire abdominal area S0 can be calculated from the measured value of the short axis radius a and the abdominal circumference c obtained by setting the measured value of the total thickness of the abdomen as the short axis diameter A by the equation (4). . Of course, instead of the abdominal circumference c, the total area S0 may be calculated from the equation (1) using the major axis radius b obtained by setting the measured value of the entire abdominal thickness as the major axis diameter B. .

  Next, when it is assumed that the outer shape of the abdominal cavity, that is, the visceral fat-containing region (visceral region) is an ellipse 56 as a similar shape of the ellipse 52 (such an assumption also from an anatomical viewpoint, Moreover, a certain validity is recognized from an empirical rule), the short axis radius of the ellipse 56 can be defined as a1, and the length is a1 = a−Δa. Δa corresponds to the distance from the measurement point 48 on the surface of the abdominal surface to the measurement point 50 of the contour of the visceral fat-containing region (visceral region contour), and is measured on the tomographic image 44 (FIG. 2).

The area S1 of the ellipse 56 can be calculated from the overall area S0 using the ratio of the minor axis radius a to the minor axis radius a1 as follows.
S1 = (a1 / a) ² S0 (5)

  However, since the spine exists on the back side of the abdominal aorta in the ellipse 56 and it is necessary to exclude that portion, the range of 120 degrees on the back side in the ellipse 56 (line 58 and line 60). Excluding the fan-shaped range sandwiched between the left and right sides, the remaining 240-degree range 61, that is, 2/3 of the entire range, becomes an effective region. In addition, since organs other than visceral fat exist in the visceral fat-containing region approximated by an ellipse, it is necessary to exclude them. Therefore, a predetermined numerical value α (for example, 10 and may be a numerical value obtained by multiplying S1 by a predetermined coefficient instead) as an exclusion amount. Considering these two correction conditions, the visceral fat area S2 is calculated as follows.

S2 = (a1 / a) ² S0 × 2 / 3−α (6)

  This calculation is an estimate of the effective area where visceral fat is present in the abdomen, and the area S2 can be used as an index value, and a correction based on the personal parameter value is applied to the area S2. Then, the result value can be used as an index value. As will be described later, while using only three actually measured values of the subcutaneous fat thickness (Δa), the entire abdominal length (A), and the entire abdominal width (B) (instead of the abdominal total width (B), the abdominal circumference (C) may be used), by fitting these measured values to the elliptical approximate model of the abdominal and visceral fat-containing regions, and further applying the necessary corrections to obtain a high practical value, that is, a reliable index value. It is possible to obtain. In addition to the above three actual measurement values, other actual measurement values can be used.

  FIG. 5 is an overall configuration diagram of an ultrasonic diagnostic system suitable for implementing the present invention. The ultrasonic diagnostic system of FIG. 5 is configured by an ultrasonic diagnostic apparatus. However, the image processing and the index value calculation can be executed by a computer (including a tablet terminal).

  The ultrasonic diagnostic system shown in FIG. 5 is roughly composed of a main body 66 and a probe 36. The main body 66 is a main body portion of the ultrasonic diagnostic apparatus, and the probe 36 is connected to the main body 66 via a cable. The probe 36 is used in contact with the body surface of the subject. The probe 36 includes an array transducer including a plurality of vibration elements. The array transducer is a 1D array transducer. An electron beam B is formed by the array transducer, and the scanning surface 69 is configured by scanning the electron beam B in the electronic scanning direction θ. In addition, r has shown the depth direction. As the electronic scanning method, an electronic linear scanning method, an electronic convex scanning method, an electronic sector scanning method, and the like are suitable. A so-called 3D probe may be used as the probe 36.

  Next, the main body 66 will be described. The transmission / reception unit 68 functions as a transmission beamformer and a reception beamformer. At the time of transmission, the transmission / reception unit 68 supplies a plurality of transmission signals to the probe 36 in parallel. As a result, a transmission beam is formed at the probe 36. At the time of reception, the reflected wave from the subject (inside the living body) is received by the array transducer, and a plurality of received signals are output to the transmission / reception unit 68 therefrom. In the transmission / reception unit 68, a phasing addition process is executed on a plurality of reception signals, thereby electronically forming a reception beam. The reception signal after the phasing addition, that is, the beam data obtained as a result is output to the signal processing unit 70.

  The signal processing unit 70 has a known circuit such as a detection circuit or a logarithmic conversion circuit, and executes predetermined signal processing on the beam data. The beam data after the signal processing is output to the image forming unit 72. The image forming unit 72 includes a digital scan converter (DSC), that is, forms a B-mode tomographic image based on a plurality of beam data. The image data is sent to the display unit 76 via the display processing unit 74, and the tomographic image is displayed on the screen in the display unit 76.

  The measuring unit 78 measures the distance from the body surface near the umbilicus of the subject to the visceral region contour on the tomographic image as the subcutaneous fat thickness. The measurement unit 78 is a module that executes distance measurement based on coordinates designated by the user on the tomographic image. In this embodiment, the distance Δa from the body surface of the abdomen near the navel of the subject to the visceral region contour is measured. The measurement is executed after the user (inspector) appropriately adjusts the contact position and contact posture of the probe 36 while viewing the tomographic screen. The measurement result obtained by the measurement unit 78 is sent to the display processing unit 74 as necessary.

  The index value calculation unit 80 includes the subcutaneous fat thickness (distance Δa) measured by the measurement unit 78, the abdominal total longitudinal thickness (length A) and the abdominal total lateral thickness (length B) obtained via the control unit 84. Alternatively, this is a module for deriving an index value of the visceral fat of the subject based on the measurement data of the abdominal circumference c and based on a plurality of personal parameter values described later. In that case, the coefficient group stored in the coefficient table 82 is referred to, that is, the index value is calculated using a plurality of coefficient values. An index value as a calculation result, that is, a value representing the visceral fat mass is sent to the display processing unit 74, and the index value is displayed as a numerical value or the like on the display unit 76. In this case, various parameter values used in the process of calculating the index value may be simultaneously displayed on the screen. The calculation of the index value and the coefficient group will be described later.

  The control unit 84 performs operation control of each component shown in FIG. An input unit 86 is connected to the control unit 84. The input unit 86 is composed of a keyboard, a trackball, and the like. The input unit 86 may be a port that receives information from the network, and the input unit 86 may be a card reader or the like. In this embodiment, the coordinates of the marker used for measurement are specified by the user using the input unit 86. In addition, using the input unit 86, the measurement values of the entire abdomen vertical thickness and the entire abdomen horizontal thickness (or abdominal circumference) are input. Note that measurement values (measurement data) of the entire abdominal length and thickness (or abdominal circumference) may be input from a measuring instrument (not shown). Further, a plurality of personal parameter values are input as subject information using the input unit 86. Such information may be input via a backbone network in a medical institution.

  Incidentally, it is desirable that the measuring instrument for measuring the entire thickness of the abdomen and the entire thickness of the abdomen (or the abdomen circumference) is a non-contact type measuring instrument using a laser or an ultrasonic sensor, for example. If it is a non-contact type, the measurement error by crushing the body surface of a subject can be avoided. Moreover, it is desirable that the measurement by the measuring instrument is performed at a measurement position based on the position of the subject's navel. For example, at the position corresponding to the cross section of the abdomen including the subject's umbilicus (or the vicinity thereof), the entire abdomen vertical thickness and the entire abdomen horizontal thickness (or abdominal circumference) are measured.

  In FIG. 6, the operation of the index value calculation unit 80 is shown as a conceptual diagram. A calculation formula (function) for calculating the index value exists in the index value calculation unit 80, and the numerical values given to the items of the calculation formula are shown in FIG. First, for the index value calculation unit 80, as a measurement value that is a measurement result, subcutaneous fat thickness (distance Δa), abdominal overall vertical thickness (length A), abdominal overall lateral thickness (length B), or abdominal circumference length c is input. Further, various numerical values such as height, weight, BMI, and age, which are individual parameter values, are input to the index value calculation unit 80. In calculating the index value, the abdominal circumference c may be used as a correction parameter value in addition to the calculation of the entire area. The index value calculation unit 80 is provided with a plurality of coefficient values [k1, k2,..., Kn] 92 from the coefficient table described above. Based on the numerical value set given as described above, the index value calculation unit 80 assigns them to a predetermined calculation formula, and calculates an index value 98 representing the visceral fat mass as the calculation result.

  The index value calculation unit 80 may prepare a calculation formula for each age or nationality. In that case, for example, an appropriate calculation formula is selected as indicated by reference numeral 94 according to the country (region), sex, etc. as indicated by reference numeral 96, and the index value calculation unit 80 selects the selected calculation. It is desirable that the index value is calculated using an expression.

  Next, the calculation of the index value considering the personal parameter value will be described. In order to further improve the estimation accuracy of the visceral fat amount, that is, the index value, when calculating the index value, in addition to the above-described measurement values (subcutaneous fat thickness Δa, abdominal overall vertical thickness A, abdominal overall lateral thickness B or abdominal circumference length c), It is desirable to consider personal parameter values. The personal parameter value referred to in this case has a correlation with the visceral fat mass, and is preferably a general personal parameter value measured in a normal health examination or the like. In the present embodiment, height, weight, BMI, and age are considered in addition to the above three actual measurement values. Specifically, the corrected visceral fat amount (area) S3 is calculated as follows. In the following, height, weight, BMI, and age are numerical values.

S3 = k1 * height + k2 * weight + k3 * BMI
+ K4 * abdominal circumference c + k5 * age + k6 * S2 (7)

  In the above, S2 is calculated | required from said (6) Formula. In the equation (7), the abdominal circumference (abdominal circumference) c is reused as the correction parameter value. In the above, k1 to k6 are coefficients (weighting coefficients), and k1 = 1.04625, k2 = −0.66080, k3 = 6.42130, k4 = 0.09900, k5 = 1.17187, k6 = 0.47235 is obtained. Note that the value of k4 is small, and it can be pointed out that re-consideration of the abdominal circumference c is not necessarily required. In any case, the above calculation formulas and coefficients are merely examples.

  For example, BMI is obtained from height and weight, and as a result, height and weight are used twice as correction parameter values. In addition, the higher the height, the heavier the weight tends to be, and a certain degree of correlation is recognized between the height and the weight.

  When using multiple regression analysis (multivariate analysis) to obtain an estimated value, for example, an estimated value of visceral fat mass, use multiple correction parameters that are weakly correlated with each other in order to improve the accuracy of the estimated value. Is desirable. For example, in equation (7), BMI, height, and weight are used as correction parameters. However, since BMI, height, and weight have a relatively strong correlation with each other, for example, any one of BMI, height, and weight is selected. It is desirable to use only one as a correction parameter. The strength of the correlation can be evaluated by, for example, a correlation value (correlation coefficient). For example, it is determined that the correlation between two correction parameters whose correlation value (correlation coefficient) is equal to or greater than a threshold is strong. In this case, only one of these two correction parameters is used. Specific examples of the plurality of correction parameters having a weak correlation with each other include height, age, and sex.

  FIG. 7 is a diagram for explaining the position of ultrasonic measurement. In the present embodiment, the distance from the body surface 12 of the abdomen of the subject (living body 10) to the contour of the visceral fat-containing region 20 (visceral region contour) by measurement on a tomographic image obtained using a probe ( Δa) shown in FIGS. 2 to 3 is measured.

  In the cross section (transverse section) of the subject, the visceral fat-containing region (visceral region) 20 is entirely surrounded by the muscle layer 16. In the portion in contact with the muscle layer 16, the visceral region outline, that is, the outer edge of the visceral fat-containing region 20 is the inner surface (reference numeral 16 </ b> A) of the muscle layer 16. The muscle layer 16 has a relatively large difference in thickness for each part (depending on the position). Therefore, when the distance from the body surface 12 of the abdomen is measured using the inner surface of the muscle layer 16 as a measurement point, the measurement results vary depending on the measurement position. For example, as in the specific example shown in FIG. 7, the measurement point P <b> 1 and the measurement point P <b> 2 are different in distance from the body surface 12 because the thickness of the muscle layer 16 is different.

  Therefore, in order to suppress variations in measurement results depending on the position, a measurement point P0 is set on the visceral region contour in the vicinity of the umbilicus N, that is, the outer edge of the visceral fat-containing region 20, and from the abdominal body surface 12 to the measurement point P0. The distance is measured. As in the specific example shown in FIG. 7, generally, in the vicinity of the umbilicum N, there is a portion where the muscle layer (stratus abdominis muscle) 16 does not exist or is extremely thin due to the structure of the living body. In that portion, the outer edge of the visceral fat-containing region 20, that is, the visceral region contour can be specified without being affected by the thickness of the muscle layer 16 or in a state where the influence is extremely small. Further, in a portion where the muscle layer 16 does not exist or is extremely thin, the distance from the abdominal body surface 12 to the outer edge (visceral region outline) of the visceral fat-containing region 20 can be regarded as the thickness of the subcutaneous fat layer 14.

  For the above reasons, the measuring unit 78 (FIG. 5) determines the distance from the body surface 12 near the umbilical N of the subject to the visceral region contour (the outer edge of the visceral fat-containing region 20) on the tomographic image. Measure as

  Further, according to the knowledge based on actual measurement by the inventors, there is a relatively strong correlation between the area of the subcutaneous fat layer (subcutaneous fat region) 14 and the subcutaneous fat thickness. Therefore, for example, it is possible to estimate the area of the subcutaneous fat layer (subcutaneous fat region) 14 from the measured value of the subcutaneous fat thickness, and certain validity is recognized for the estimation. Furthermore, in the knowledge based on actual measurement by the inventors, a relatively strong correlation is recognized between the difference area obtained by subtracting the subcutaneous fat area from the entire abdominal area and the area of the visceral fat-containing region (visceral region). Therefore, the index value calculation unit 80 (FIG. 5) approximates the shape of the entire abdomen of the subject using an ellipse model (the ellipse 52 in FIG. 4), and the entire abdomen area according to the above-described equation (1) or (4). S0 may be calculated to obtain a differential area obtained by subtracting the subcutaneous fat area estimated from the subcutaneous fat thickness from the entire abdominal area S0, and the visceral region area may be estimated from the differential area. This estimation is sufficiently valid in terms of empirical rules or anatomical viewpoints and in the actual measurement by the inventors.

  FIG. 8 is a diagram showing a specific example 1 of a marker displayed as a guide for ultrasonic measurement. FIG. 8 shows a specific example of a tomographic image 44C obtained by convex scanning. The tomographic image 44C is an image in the abdomen of the subject obtained by transmitting and receiving ultrasound from the body surface near the navel of the subject. On the tomographic image 44C, the measurement point 12P corresponding to the body surface of the abdomen and the measurement point P0 corresponding to the visceral region contour are set, and the distance (Δa) between the measurement point 12P and the measurement point P0 is measured as the subcutaneous fat thickness. .

  When an ultrasound image is formed by bringing the probe into contact with the body surface near the umbilicus, the intimate contact between the umbilical portion recessed from the body surface and the wave transmitting / receiving surface of the probe is incomplete, and the incomplete portion is superficially inside the abdomen. Since a sound wave reception signal cannot be obtained, a dark shadow occurs in the ultrasonic image. In the convex scan, for example, as in the specific example shown in FIG. 8, a shadow region S having a divergent shape appears in the tomographic image 44C due to the umbilicus of the subject.

  Therefore, the display processing unit 74 (FIG. 5) forms a line-shaped measurement marker ML having a predetermined positional relationship with the position of the shadow region S with reference to the position of the shadow region S in the tomographic image 44C. . For example, as in the specific example shown in FIG. 8, a line-shaped reference marker BL serving as a position reference is formed in the tomographic image 44C, and the measurement marker ML is formed at an angle θ from the reference marker BL. The

  The user (inspector) observes the tomographic image 44C displayed on the display unit 76 (FIG. 5) so that the reference marker BL is in the shadow area S, for example, the reference marker BL is positioned at the center of the shadow area S. Adjust the position and orientation of the probe to pass. With the adjustment, the measurement marker 12P corresponding to the body surface of the abdomen and the measurement point P0 corresponding to the visceral region contour are set on the measurement marker ML while the reference marker BL is aligned in the shadow region S. The distance (Δa) between the point 12P and the measurement point P0 is measured as the subcutaneous fat thickness.

  Thereby, for example, the subcutaneous fat thickness can be measured on the measurement marker ML displayed on the image in the abdomen as close to the navel as possible with reference to the position of the shadow region S caused by the navel. . The angle θ may be a fixed value set in advance in the apparatus, or the user (inspector) may be able to adjust the angle θ.

  FIG. 9 is a diagram illustrating a specific example 2 of a marker displayed as a guide for ultrasonic measurement. FIG. 9 shows a specific example of the tomographic image 44L obtained by linear scanning. The tomographic image 44L is also an image in the abdomen of the subject obtained by transmitting and receiving ultrasonic waves from the body surface near the navel of the subject.

  In the linear scanning, for example, as in the specific example shown in FIG. 9, a band-like shadow region S appears in the tomographic image 44L due to the umbilicus of the subject. The display processing unit 74 (FIG. 5) forms a measurement marker ML having a predetermined positional relationship with the position of the shadow region S with reference to the position of the shadow region S in the tomographic image 44L. For example, as in the specific example shown in FIG. 9, a reference marker BL serving as a position reference is formed in the tomographic image 44L, and a measurement marker ML is formed at a distance D from the reference marker BL.

  The user (inspector) looks at the tomographic image 44L displayed on the display unit 76 (FIG. 5) so that the reference marker BL is in the shadow area S, for example, the reference marker BL is positioned at the center of the shadow area S. Adjust the position and orientation of the probe to pass. With the adjustment, the measurement marker 12P corresponding to the body surface of the abdomen and the measurement point P0 corresponding to the visceral region contour are set on the measurement marker ML while the reference marker BL is aligned in the shadow region S. The distance (Δa) between the point 12P and the measurement point P0 is measured as the subcutaneous fat thickness.

  Thereby, for example, the subcutaneous fat thickness can be measured on the measurement marker ML displayed on the image in the abdomen as close to the navel as possible with reference to the position of the shadow region S caused by the navel. . The distance D may be a fixed value set in advance in the apparatus, or the user (inspector) may be able to adjust the distance D.

  8 and 9, the reference marker BL is preferably set to pass through the center of the shadow area S, for example, but may be set to the outer edge of the shadow area S or the edge of the tomographic image, for example. Good. Further, for example, the reference marker BL may be set at a reference position in the tissue image, such as a boundary between the rectus abdominis muscle and the internal oblique muscle or a bone.

  As mentioned above, although preferred embodiment of this invention was described, according to embodiment mentioned above, the effect demonstrated below is acquired, for example.

  In general, when performing ultrasonic diagnosis or ultrasonic measurement of a deep part in a subject, the ultrasonic probe tends to be pressed relatively strongly against the body surface of the subject, and measurement is performed according to the amount of the pressing force. Variations can occur.

  On the other hand, in this embodiment, since the ultrasonic measurement is in the vicinity of the body surface of the subject (see FIGS. 2 and 3), the probe is applied to the body surface with a relatively weak force compared to the case of the deep part. Measurement by the contact state can be realized, and variation in measurement due to pressing can be reduced.

  In addition, when ultrasonic diagnosis or ultrasonic measurement is performed on a deep part in a subject, it is easily affected by the contact angle of the probe with the body surface, but in this embodiment, ultrasonic measurement is performed near the body surface of the subject. Therefore, it is less susceptible to the influence of the contact angle of the probe with the body surface than in the case of the deep part.

  In addition, although measurement in the deep part may be difficult for a relatively thick subject, for example, in the present embodiment, since the measurement target is near the body surface, it is also meaningful when the subject is relatively fat. Measurement results can be obtained.

  Furthermore, the measurement near the body surface as in this embodiment is less susceptible to the influence of the subject's breathing than the measurement in the deep part.

  As described above, this embodiment has a number of advantages. As a result, the measurement error due to the difference between users (examiners) and the measurement error due to the difference between facilities (for example, hospitals) can be reduced or eliminated. Be expected.

  10 Abdomen, 14 Subcutaneous fat layer, 16 Muscle layer, 20 Visceral fat containing region, 36 probe, 52 Ellipse approximating the abdominal contour, 56 Ellipse approximating the external shape of the visceral fat, 72 Image forming unit, 74 Display processing unit 78 Measurement unit, 80 Index value calculation unit.

Claims (10)

An image forming unit that forms an ultrasound image in the abdomen of the subject based on a reception signal obtained by transmitting and receiving ultrasound; and
On the ultrasonic image, a measurement unit that measures the distance from the body surface near the umbilicus of the subject to the visceral region contour as subcutaneous fat thickness,
A data acquisition unit for obtaining measurement data of the entire abdominal longitudinal thickness which is the thickness in the front-rear direction of the entire abdomen of the subject;
In the process of deriving an index value of the visceral fat in the visceral region by approximating the cross section of the entire abdomen with an elliptical shape, the overall abdominal longitudinal thickness and the subcutaneous fat thickness are set as the input values of the process, and the output values of the process An index value deriving unit for obtaining an index value of visceral fat of the subject;
Having
An ultrasonic diagnostic system characterized by that. The ultrasonic diagnostic system according to claim 1,
The index value deriving unit removes the subcutaneous fat area based on the subcutaneous fat thickness from the entire abdominal area obtained by adapting an elliptical shape to a cross section of the entire abdomen of the subject according to the vertical thickness of the entire abdomen. Calculating the visceral area by deriving at least one of the visceral fat area estimated from the visceral area and the visceral area as the index value,
An ultrasonic diagnostic system characterized by that. The ultrasonic diagnostic system according to claim 2,
In addition to the entire abdominal longitudinal thickness, the data acquisition unit measures the measurement data of the entire abdominal width that is the thickness of the entire abdomen of the subject or the circumference of the entire abdomen of the subject. Get the data,
The index value deriving unit adapts an elliptical shape to a cross section of the entire abdomen of the subject according to the entire abdomen vertical thickness and the entire abdomen horizontal thickness or the peripheral length.
An ultrasonic diagnostic system characterized by that. In the ultrasonic diagnostic system according to any one of claims 1 to 3,
The image forming unit forms a tomographic image in the abdomen of the subject as the ultrasonic image,
A measurement marker having a predetermined positional relationship with respect to the position is formed in the tomographic image with reference to the position of a band-like or divergent shadow region generated in the tomographic image due to the umbilicus of the subject. A display processing unit;
An ultrasonic diagnostic system characterized by that. The ultrasonic diagnostic system according to claim 4,
The display processing unit forms a reference marker to be aligned with the shadow region in the tomographic image.
An ultrasonic diagnostic system characterized by that. The ultrasonic diagnostic system according to claim 5,
The display processing unit forms a line-shaped reference marker and a line-shaped measurement marker at a predetermined interval with respect to the reference marker in the tomographic image,
The subcutaneous fat thickness is measured on the measurement marker in a state where the reference marker is aligned in a shadow region generated in the tomographic image,
An ultrasonic diagnostic system characterized by that. In the ultrasonic diagnostic system according to any one of claims 1 to 6,
In the measurement position based on the position of the subject's umbilicus, further has a measuring instrument that measures the entire thickness of the abdomen without contact with the body surface of the subject.
An ultrasonic diagnostic system characterized by that. In the ultrasonic diagnostic system according to any one of claims 1 to 7,
A correction unit that corrects the index value of the subject by using a plurality of parameters that satisfy a condition that indicates that the correlation between the plurality of parameters is weak with each other.
An ultrasonic diagnostic system characterized by that. The ultrasonic diagnostic system according to claim 8,
The plurality of parameters satisfying the condition include the subject's sex, age and height,
An ultrasonic diagnostic system characterized by that. A measurement unit that measures the distance from the body surface near the umbilicus of the subject to the visceral region contour on the ultrasonic image in the abdomen of the subject obtained by sending and receiving ultrasound as subcutaneous fat thickness;
A data acquisition unit for obtaining measurement data of the entire abdominal longitudinal thickness which is the thickness in the front-rear direction of the entire abdomen of the subject;
In the process of deriving an index value of the visceral fat in the visceral region by approximating the cross section of the entire abdomen with an elliptical shape, the overall abdominal longitudinal thickness and the subcutaneous fat thickness are set as the input values of the process, and the output values of the process An index value deriving unit for obtaining an index value of visceral fat of the subject;
Having
An information processing apparatus characterized by that.

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