JP5787286B2 - Ultrasound biological tissue measuring device - Google Patents

Description

  The present invention relates to an ultrasonic biological tissue measuring apparatus, and for example, relates to an ultrasonic biological tissue measuring apparatus that can obtain information on tissue hardness from a pressing force against tissue and a change in tissue thickness.

  A conventional ultrasonic echo device used in a medical field diagnoses the state of a tissue from the shape of an image displayed. At that time, the probe is empirically pressed against the body for reference of tissue identification.

  An apparatus called elastography in which a function capable of measuring tissue elastic modulus is added to a conventional ultrasonic echo apparatus has been developed. This is a device that presses the probe against the body, reads the degree of tissue deformation from the image, and estimates the relative elastic modulus from the amount of strain. The configuration of the apparatus is the same as that of a normal ultrasonic echo apparatus. It is calculated by software built into the device from the ultrasonic signals before and after pressing. Since this device does not measure the pressing force, the elastic modulus can only be obtained relative to the surrounding tissue.

  In existing patents, there is a technique for measuring a pressing force and a moving amount of a probe and calculating a value related to hardness. For example, there are the following technologies.

  (1) A technique related to a soft tissue viscoelasticity estimation apparatus and program using ultrasonic waves described in Patent Document 1 is applied to soft tissue having a hierarchical structure with skin, fat, muscle, bone, and the like, such as body tissue. Is a technique for estimating elasticity, viscosity, and inertia in each layer. Specifically, an ultrasonic probe for transmitting and receiving an ultrasonic signal, an object deformation amount calculation unit for calculating the deformation amount of the object shape from the time change of the received data, and an ultrasonic probe to move Moving mechanism, probe control unit for controlling the same, position sensor for measuring the position of the probe, force sensor for measuring the force applied to the probe unit, position sensor, force sensor, deformation amount of the object The viscoelasticity estimation unit estimates the viscoelasticity of the object based on the values obtained from the respective calculation units, and the viscoelasticity display unit presents the estimated viscoelasticity to the user.

  (2) Patent Document 2 describes an ultrasonic diagnostic apparatus. Specifically, a position detection means for detecting three-dimensional position information represented by a magnetic sensor is attached to an ultrasonic probe, and the position detection means is based on a base point fixed to a certain point. To grasp the spatial position.

  (3) Patent Document 3 describes a technique related to an ultrasonic probe and an ultrasonic diagnostic apparatus. Specifically, a tube filled with a pressure transmission medium is provided around the transducer provided on the contact surface of the ultrasonic probe that contacts the subject, and the pressure of the pressure transmission medium in the tube is detected. A pressure sensor is provided to measure the contact pressure at which the contact surface of the ultrasonic probe is pressed against the subject by an external measuring device or the like.

  (4) Patent Document 4 describes a technique relating to elastography measurement, an imaging method, and an apparatus for performing this method. Specifically, standard transducers or axially translated transducer devices are used to compress or move the proximal end region of the target body by a known small increment. Here, at each increment, a pulse is emitted and an echo sequence (A-line) is detected from the sound travel path in the target or the area along the transducer beam. The time shift in the echo segment corresponding to the feature in the target is corrected for each zone of varying sound speed along the sound path to provide relative quantitative information about the distortion caused by the compression.

  (5) Patent Document 5 describes a technique related to an ultrasonic diagnostic apparatus. Specifically, a displacement measuring means for calculating a moving amount or displacement of each point on the tomographic image by performing an operation between two time-series tomographic images obtained by the tomographic scanning means, and a body cavity of the diagnosis part of the subject A pressure measuring means for measuring or estimating the internal pressure; an elastic modulus calculating means for calculating elastic modulus at each point on the tomographic image from the displacement and pressure obtained by each measuring means; A hue information conversion means for inputting hue image information by inputting elasticity image data from the means, a black and white tomographic image data from the tomographic scanning means, and a color change image data from the hue information conversion means. And the image data from the switching addition means is displayed on the image display means.

  (6) Patent Document 6 describes a technique related to a method for detecting the hardness of a living soft tissue and a detection apparatus used therefor. Specifically, this detection apparatus amplifies an output signal from a sensor unit including an objective contact vibrator and a vibration detection unit and an output from the sensor unit, and passes this through a band-pass filter or a peaking amplifier. The self-excited oscillation circuit unit that is forcibly fed back to the self-excited oscillation circuit and a measurement unit that measures the amount of frequency change of the self-excited oscillation circuit.

  (7) Patent Document 7 discloses a muscle hardness measuring device that calculates a compressibility of a muscle layer from a pressing force when the probe is pressed against a measurement target portion and a change in thickness of the muscle layer before and after pressing. Is described.

Japanese Patent Laying-Open No. 2005-144155 (released on June 9, 2005) JP 2004-89362 A (published on March 25, 2004) Japanese Patent Laid-Open No. 08-036233 (published February 6, 1996) JP-T-2001-519664 (published on October 23, 2001) JP 05-317313 A (released on December 3, 1993) Japanese Patent Laid-Open No. 8-29312 (published February 2, 1996) JP 2008-168063 A (released July 24, 2008)

  In the technique described in Patent Document 1, it is necessary to measure the amount of movement of the probe in some form in order to calculate the amount of deformation of the tissue in addition to the mechanism for measuring the pressing force. Therefore, there is a mechanism for measuring the amount of movement. It becomes necessary and the device mechanism becomes large, and it is difficult to use it at the actual measurement site. Further, there is a problem that handling around the probe becomes difficult during use, and it is difficult to ensure portability.

  The technique described in Patent Document 2 requires a mechanism for detecting the three-dimensional position information of the probe. Also, the pressing force is not measured.

  The technique described in Patent Document 3 is a technique that measures the pressing force and issues a warning by an alarm sound or the like when the contact pressure between the probe and the living body exceeds a predetermined pressure, and cannot perform accurate measurement.

  The technique described in Patent Document 4 moves the ultrasonic probe with a motor to deform the tissue, and therefore requires a separate control device around the motor, and does not measure the pressing force.

  The technique described in Patent Document 5 is an invasive method in which a pressure sensor is inserted into a living body to measure internal stress.

  The technique described in Patent Document 6 is a technique for measuring the elastic modulus by changing the frequency of ultrasonic waves, and it is difficult to perform a calibration process for eliminating the influence of the frequency from the measurement result, which is not practical.

  The technique described in Patent Document 7 calculates the compression ratio of the muscle when pressed, but cannot measure the hardness of the tissue. Further, since there is a spring between the pressure sensor and the probe, the pressing force cannot be measured accurately.

  An object of the present invention is to provide an ultrasonic biological tissue measuring apparatus that can calculate a value relating to tissue hardness from the relationship between the pressing force of an ultrasonic probe and the deformation of a tissue in a non-invasive manner in view of the problems of the conventional example. Is to provide.

In order to solve the above problems, an ultrasonic biological tissue measurement device according to the present invention emits an ultrasonic wave to a measurement target tissue and receives an ultrasonic wave reflected from the measurement target tissue;
A pressing force measuring unit that measures a force pressing the ultrasonic probe against the measurement target tissue; and an elastic index calculating unit, wherein the elastic index calculating unit receives the measurement result received from the pressing force measuring unit, and The elasticity index of the measurement target tissue is calculated from the change in the thickness of the measurement target tissue detected from the ultrasonic signal received by the ultrasonic probe, and the pressing force measurement unit includes the ultrasonic probe measured by the measurement target tissue. A strain sensor that measures the distortion of the ultrasonic probe that is generated when pressed against the body, or the ultrasonic probe is stored in a housing, and the ultrasonic probe is pressed against the tissue to be measured when the ultrasonic probe is pressed against the measurement target tissue. It is a pressure sensor that measures the pressure generated when the acoustic probe is pressed against the housing.

  According to the above configuration, the elasticity index calculation unit can calculate the elasticity index of the tissue non-invasively based on the change in the thickness of the tissue corresponding to the pressing force against the tissue and the pressing force. Further, pressing and pressing force can be easily measured by a strain sensor or a pressure sensor.

  In the ultrasonic biological tissue measurement apparatus according to the present invention, the pressing force measurement unit is a strain sensor that measures distortion of the ultrasonic probe that occurs when the ultrasonic probe is pressed against a measurement target tissue. Also good.

  Since the pressing force measuring unit directly measures the distortion of the ultrasonic probe itself, the structure of the measuring unit can be simplified.

  Further, in the ultrasonic biological tissue measuring apparatus according to the present invention, the ultrasonic probe is stored in a housing having an opening in a state where an end surface pressed from the opening to the measurement target tissue of the ultrasonic probe is projected. The pressing force measurement unit is a pressure sensor that measures a pressure generated when the ultrasonic probe is pressed against the housing when the ultrasonic probe is pressed against the measurement target tissue. The sensor may be installed between the surface of the ultrasonic probe and the housing on a line passing through the center of gravity of the end surface and perpendicular to the end surface.

  Since the pressure sensor is installed on the center of gravity of the end face, the pressure between the ultrasonic probe and the housing that is generated when the ultrasonic probe is pressed can be measured more accurately. For example, when there is no pressure sensor on the center of gravity of the end surface, it is affected by the moment according to the distance of the center of gravity from the point where the straight line passing through the pressure sensor perpendicular to the end surface intersects the end surface. The pressure can be measured while suppressing the influence of this moment.

  Further, in the ultrasonic biological tissue measurement device according to the present invention, the elasticity index calculation unit is set in advance, the elasticity index, the amount of change in the thickness of the measurement target tissue, the pressing force against the measurement target tissue, More preferably, the elasticity index is calculated based on the measured change amount and the pressing force from the relationship information indicating the relationship with the information indicating which layer the measurement target tissue has.

  In the above relationship information, the amount of change in the thickness of the measurement target tissue, the pressing force against the measurement target tissue, and information indicating which layer is the measurement target when the measurement target tissue has a layer structure and the elasticity index Since the relationship is determined in advance, the elasticity index can be calculated more accurately based on the relationship information. In addition, for example, the type of the tissue to be measured is determined in advance, and the relationship information corresponding to the type of tissue is set in advance (recorded in a recording unit such as a memory), thereby more accurately The elasticity index of the tissue to be measured can be calculated.

  In the ultrasonic biological tissue measurement device according to the present invention, the relation information includes the elasticity index, the amount of change in the thickness of the measurement target tissue, the pressing force against the measurement target tissue, and the measurement target tissue has a layer structure. It is more preferable that the information represents the relationship between the information indicating the layer at times and the information indicating the type of the tissue to be measured.

  By including information indicating the type of the measurement symmetrical tissue in the relationship information, it is possible to calculate the elasticity index for various types of tissue.

  According to the present invention, an ultrasonic probe that emits ultrasonic waves to a measurement target tissue and receives ultrasonic waves reflected from the measurement target tissue, and a force for pressing the ultrasonic probe against the measurement target tissue are measured. A pressing force measurement unit; and an elasticity index calculation unit, wherein the elasticity index calculation unit is a thickness of a measurement target tissue detected from a measurement result received from the pressing force measurement unit and an ultrasonic signal received by the ultrasonic probe. The elasticity index of the tissue to be measured is calculated from the change in thickness, and the pressing force measurement unit is a strain that measures the distortion of the ultrasound probe that occurs when the ultrasound probe is pressed against the tissue to be measured. The sensor or the ultrasonic probe is housed in the housing, and the ultrasonic probe is moved to the housing when the ultrasonic probe is pressed against the measurement target tissue. Since it is a pressure sensor that measures the pressure generated by being attached, there is an effect that a value related to tissue hardness can be calculated non-invasively from the relationship between the pressing force of the ultrasonic probe and the deformation of the tissue. .

1 is a diagram schematically showing a configuration of an ultrasonic biological tissue measuring apparatus 1 according to an embodiment of the present invention. It is a figure which shows typically the structure of the measurement part 2 with which the ultrasonic biological tissue measuring device 1 which concerns on one Embodiment of this invention is provided. It is a figure which shows the kind of measuring method of the structure | tissue by an ultrasonic wave. It is explanatory drawing for demonstrating the method of calculating | requiring a tissue position. It is a figure for demonstrating the process of the ultrasonic biological tissue measuring apparatus 1 which concerns on one Embodiment of this invention. It is a figure which shows the position of the layer of an echo image and a structure | tissue. It is a figure which shows the mode of a structure | tissue when changing pressing force, and the change of thickness. FIG. 8 is a diagram showing a graph of the change rate characteristic table from the initial pressing force in FIG. It is a figure which shows typically the expansion-contraction aspect of each structure | tissue layer when pressing force is applied to a structure | tissue. FIG. 6 is a characteristic diagram of an elasticity index with respect to the pressing force of the BC layer and the CD layer of the tissue in FIG. 5. It is a flowchart which shows an example of operation | movement of the ultrasonic biological tissue measuring apparatus 1 which concerns on one Embodiment of this invention. It is a figure which shows an example of the state-thickness correlation information in this invention. It is a figure which shows the relationship between the rectus femoral muscle thickness and subcutaneous fat thickness for every test subject.

  Hereinafter, an embodiment of an ultrasonic biological tissue measuring apparatus according to the present invention will be described in detail.

<Configuration of ultrasonic biological tissue measuring apparatus 1>
First, the configuration of the ultrasonic biological tissue measuring apparatus 1 according to the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a diagram schematically showing a configuration of an ultrasonic biological tissue measuring apparatus 1. FIG. 2 is a diagram schematically illustrating the configuration of the measurement unit 2. As shown in FIG. 1, the ultrasonic biological tissue measurement apparatus 1 includes a measurement unit 2 and an analysis unit 3. In the present embodiment, the hardness of the tissue (measurement target tissue) 11 is measured.

[Configuration of Measuring Unit 2]
The measuring unit 2 includes an ultrasonic probe 4 and a pressing force measuring sensor (pressing force measuring unit) 5.

  As shown in FIG. 2A, the measurement unit 2 has four pressing force measurement sensors 5 attached around the ultrasonic probe 4. The pressing force measurement sensor 5 is a strain sensor that measures the distortion of the ultrasonic probe 4 that occurs when the ultrasonic probe 4 is pressed against the tissue 11. In the present embodiment, the measurement unit 2 is pressed against the tissue 11 in the direction of the arrow A.

  The material of the ultrasonic probe 4 may be any material that can detect ultrasonic waves (echoes) that emit and reflect ultrasonic waves, and can be distorted by being pressed against the tissue. , Polymer materials, ABS resin, PBT, acrylic, polycarbonate, and composites thereof. Further, the ultrasonic probe 4 converts the ultrasonic wave reflected from the tissue 11 into an ultrasonic signal for transmitting to the ultrasonic transmitting / receiving unit 6 described later.

  The pressing force measuring sensor 5 (strain sensor) may be any sensor that can measure the strain of the ultrasonic probe 4. For example, a conventionally known strain sensor can be used. The position where the pressing force measurement sensor 5 is provided may be a position where the distortion of the ultrasonic probe 4 can be measured, but the two pressing force measurement sensors 5 are on the surface of the ultrasonic probe 4 and are ultrasonic waves. It is preferable to arrange them symmetrically on a line passing through the center of the end face pressed against the tissue 11 of the probe 4. Thereby, the force which presses the ultrasonic probe 4 can be measured more correctly. Further, it is more preferable to provide two sets of two pressing force measuring sensors 5 arranged symmetrically as shown in FIG. 2A, and from the viewpoint of more accurate measurement, three or more sets are required. There may be.

  Reference numeral 12 denotes a cable. The cable 12 transmits a signal for generating an ultrasonic wave from the analysis unit 3 to the ultrasonic probe 4, transmits an ultrasonic signal detected by the ultrasonic probe 4 to the analysis unit 3, and the pressing force measurement sensor 5 performs measurement. This is a cable for transmitting a signal indicating the distortion to the analysis unit 3. Note that, in a modification of the measuring unit 2 described later, the cable 12 is not strained but transmits the pressure measured by the load cell to the analyzing unit 3. In addition, instead of the cable 12, distortion, pressure, or the like may be transmitted from the measurement unit 2 to the analysis unit 3 using electromagnetic waves, infrared rays, or the like.

(Another form 1 of the measuring unit 2)
Here, another form of the measurement unit 2 will be described.

  As shown in FIG. 2B, the measurement unit 202, which is another form of the measurement unit 2, includes an ultrasonic probe 204, a pressing force measurement sensor 205, and a housing 212.

  The ultrasonic probe 204 has substantially the same configuration as the ultrasonic probe 4, but differs in that a parallel movement ensuring projection 213 is formed to abut against a parallel movement securing groove provided inside the housing 212. . By forming the parallel movement securing groove and the parallel movement securing projection 213 for abutting the groove, the ultrasonic probe 204 is moved more accurately in the direction of arrow A, and the pressing force measuring sensor 205 is used to accurately The pressure generated between the ultrasonic probe 204 and the housing 212 can be measured. However, in this embodiment, as will be described later, the pressing force measurement sensor 205 is on a line passing through the center of gravity of the end surface 204a and perpendicular to the end surface 204a (on a line parallel to the pressing direction). Even without the securing groove and the parallel movement securing projection 213, the pressure between the ultrasonic probe 204 and the housing 212 can be accurately measured.

  Further, the end surface 204a of the ultrasonic probe 204 is pressed against the tissue 11, emits ultrasonic waves from the end surface 204a, and receives ultrasonic waves reflected from the tissue 11 at the end surface 204a.

  The housing 212 stores the ultrasonic probe 204. The housing 212 has an opening 212a. The ultrasonic probe 204 is stored in a state in which the end surface 204a protrudes from the housing 212 through the opening 212a.

  The pressing force measurement sensor 205 is a pressure sensor that measures the pressure generated when the ultrasonic probe 204 is pressed against the housing 212 when the ultrasonic probe 204 is pressed against the tissue 11. As a specific example of the pressing force measurement sensor 205, for example, a conventionally known load cell can be cited.

  The pressing force measurement sensor 205 (pressure sensor) passes through the center of gravity of the end surface 204a and is on a line perpendicular to the end surface 204a (in the present embodiment, coincides with a line parallel to the pressing direction), and the surface of the ultrasonic probe 204 And the housing 212. Thereby, the pressure between the ultrasonic probe 204 and the housing 212 can be accurately measured. That is, the pressure can be accurately measured by eliminating the moment B in FIG. Further, unlike Patent Document 7, since an elastic body such as a spring is not provided between the ultrasonic probe and the pressure sensor, the pressure can be accurately measured without being influenced by the elastic body.

(Another form 2 of the measuring unit 2)
A measuring unit 202 ′, which is another form of the measuring unit 2, will be described with reference to FIG. For convenience of explanation, members having the same functions as those described in the first embodiment of the measurement unit 2 are denoted by the same reference numerals, and the description thereof is omitted.

  The measurement unit 202 ′ differs from the measurement unit 202 in the number and position of the pressing force measurement sensors 205. That is, two pressing force measuring sensors 205 are provided. The two pressing force measuring sensors 205 are installed on the object centering on a straight line that is on the center of gravity of the end surface 204a and parallel to the pressing direction. With such an arrangement, the pressure can be accurately measured without the moment B shown in FIG.

(Another form 3 of the measuring unit 2)
A measuring unit 202 ″ which is another form of the measuring unit 2 will be described with reference to FIG. 2D and FIG. For convenience of explanation, members having the same functions as those described in the first embodiment of the measurement unit 2 are denoted by the same reference numerals, and the description thereof is omitted.

  The measurement unit 202 ″ differs from the measurement unit 202 in the position of the pressing force measurement sensor 205. That is, as shown in FIG. 2D, the pressing force measuring sensor 205 passes through the center of gravity of the end surface 204 a and is not on a line perpendicular to the end surface 204 a (on a line parallel to the pressing direction), like the measuring unit 202. Is provided. Therefore, since it is necessary to move the ultrasonic probe 204 in the direction of the arrow A more accurately, it is preferable to provide the parallel movement ensuring groove and the parallel movement securing protrusion 213.

  Further, even if the parallel movement ensuring groove and the parallel movement securing protrusion 213 are provided, when the measurement unit 202 ′ is pressed against the tissue 11, a moment is generated in the direction of arrow B shown in FIG. May not be able to measure the pressing force. Therefore, it is preferable to perform calculation for correcting this moment.

[Configuration of Analysis Unit 3]
The analysis unit 3 includes an ultrasonic transmission / reception unit 6, a pressing force reception unit 7, a tissue deformation amount detection unit 8, an elasticity index calculation unit 9, and a display unit 10.

  The ultrasonic transmission / reception unit 6 transmits a transmission signal for causing the ultrasonic probe 4 to emit an ultrasonic wave, receives an ultrasonic signal reflected from the tissue 11 and converted by the ultrasonic probe 4, This is output to the tissue deformation amount detection unit 8 and the display unit 10. For example, the ultrasonic transmission / reception unit 6 controls the emission of ultrasonic waves by the ultrasonic probe 4 by voltage.

  The pressing force receiving unit 7 transmits the measurement result received from the pressing force measuring sensor 5 to the elasticity index calculating unit 9.

  The tissue deformation amount detection unit 8 detects a change in the thickness of the tissue 11 from the ultrasonic signal received from the ultrasonic transmission / reception unit 6 and outputs the detection result to the elasticity index calculation unit 9. Here, the thickness refers to the thickness of the tissue 11 in the pressing direction of the force, and the change in thickness is a change in the position of the position coordinate x in the pressing direction from the surface of the tissue 11 due to the pressing of the force. It can be expressed by a certain Δx.

  The elasticity index calculation unit 9 calculates the elasticity index of the tissue 11 from the measurement result received from the pressing force reception unit 7 and the change in the thickness of the tissue 11 received from the tissue deformation amount detection unit 8. A specific calculation method will be described later. Further, the calculation result is transmitted to the display unit 10.

  The display unit 10 displays various information such as the elasticity index calculated by the elasticity index calculation unit 9.

(Measurement of tissue deformation)
Next, a tissue deformation amount measuring method performed by the tissue deformation amount detection unit 8 will be described with reference to FIGS.

  Measurements using ultrasonic waves include a method of converting the amplitude of an ultrasonic signal called B mode into luminance and displaying it as a two-dimensional image, and a method of drawing the amplitude of ultrasonic wave called A mode as a curve. FIG. 3 shows examples of the A mode and the B mode. FIG. 3 is a diagram showing types of tissue measurement methods using ultrasonic waves.

  FIG. 3A is a two-dimensional image in B mode (luminance mode), where the direction of the broken line is the depth direction from the surface of the tissue, the white portion in the image has a high luminance, and the black portion has a low luminance. Represent.

  FIG. 3B is a characteristic diagram of the A mode (luminance amplitude mode), which represents the luminance change characteristic of the broken line portion (one-dimensional image) in the two-dimensional image of the B mode, and the vertical axis represents the tissue depth direction The horizontal axis represents the luminance value. A graph in which the luminance at the broken line in the B-mode image is extracted and displayed as a change in the ultrasonic signal corresponds to the A mode.

  The amount of deformation of each tissue is obtained from this A-mode ultrasonic signal change.

  A method for obtaining a reference position (tissue position) for calculating a change in position will be described with reference to FIG. FIG. 4 is an explanatory diagram for explaining a method for obtaining a tissue position. In FIG. 4, the vertical axis represents the luminance value, and the horizontal axis represents the distance in the depth direction. The ultrasonic signal (echo signal) is output from the ultrasonic transmission / reception unit 6 in advance as an ultrasonic signal reflected from the tissue 11 and converted into a voltage by the ultrasonic probe 4.

  Therefore, if x shown in FIG. 4 is a position in the depth direction from the surface of the tissue, the tissue deformation amount detection unit 8 uses the ultrasonic signal (echo signal) change b (x) obtained via the ultrasonic transmission / reception unit 6. ) Is set with a certain width, and the maximum value of the ultrasonic signal is found within the window width W. The maximum value curve p (x) is obtained by sequentially shifting the windows in the x-axis direction at intervals smaller than the window width (preferably sufficiently small intervals, for example, 1/10 of the window width). When expressed by a mathematical expression, the following mathematical expression 1 is obtained. max is a function for obtaining the maximum value.

The center position of the portion where the maximum value previously set value do not change (the allowable variation value A _t) or more portions are continuous over the window width W and the position of the tissue (tissue location). By setting the window width to a value that minimizes the tissue thickness, the tissue position can be appropriately identified. The change (Δx) in the thickness of the tissue that changes due to the pressing force can be calculated by comparing the thicknesses of the tissues due to the two types of pressing forces. In the living tissue, the subcutaneous fat portion of the upper arm or thigh becomes the minimum thickness of the tissue, so that the window width is suitably 10 mm.

[Calculation of elasticity index]
Next, an example of a method for calculating an elasticity index by the elasticity index calculation unit 9 will be described.

  In the present embodiment, the elasticity index calculation unit 9 sets the elasticity index, the amount of change in the thickness of the tissue 11, the pressing force against the tissue 11, and where the tissue 11 has a layer structure. Elasticity index based on measured change amount and pressing force from relationship information indicating relationship between information indicating layer (hereinafter referred to as “layer information” for convenience of explanation) and information indicating type of tissue 11 Calculate

  A specific aspect of the relationship information is, for example, a table. That is, the relationship between the elasticity index, the amount of change in the thickness of the tissue 11, the pressing force against the tissue 11, the layer information, and the information indicating the type of the tissue 11 is set as a table, and the measured change amount and pressing The elasticity index is calculated based on the force and, for example, the type of tissue to be measured and the layer information input by the user or the like. This is expressed by the following formula (2).

kt = TABLE (m, Δx, n, f) (2)
In Expression (2), kt is an elasticity index, m is information indicating the type of the tissue 11, Δx is the amount of change in the thickness of the tissue 11, n is layer information, and f is for the tissue 11. It is a pressing force.

  The table may be stored in advance in a storage unit (not shown) so that the elasticity index calculation unit 9 can read the table as necessary.

  The layer information is, for example, information indicating whether the tissue for which the elasticity index is calculated is first, second,... From the top of the muscle layer, and the position of the tissue 11 from the epidermis. A number may be determined in advance and represented by the position number.

  The information indicating the type of tissue is information indicating whether the tissue to be measured is muscle or subcutaneous fat. When the tissue to be measured is fixed in advance, a table excluding information indicating the type of tissue may be used. That is, for example, when it is determined in advance that the tissue to be measured is muscle, a muscle table may be created and stored in the storage unit.

  Here, the table will be exemplified. First, a table required when the measurement target tissue m is one type will be described.

  When the measurement target tissue m has one layer, for example, a table shown in Table 1 may be created. The following table is a table for obtaining kt from Δx (mm) and f (“F (gf)” in the table). In addition, the structure of the table | surface shown below, such as a numerical value, is only an illustration, The aspect of the table (related information) used in this invention is not limited to this.

  When the organization has two layers, for example, two types of tables shown in Table 2 below may be created. If the layer information is information indicating the first layer, kt is calculated using the “first layer table”, and if the layer information is information indicating the second layer, kt is calculated using the “second layer table”. Is calculated.

  When the organization has three layers, for example, three types of tables shown in Table 3 below may be created. If the layer information is information indicating the first layer, kt is calculated using the “first layer table”, and if the layer information is information indicating the second layer, kt is calculated using the “second layer table”. If the layer information is information indicating the third layer, kt is calculated using the “third layer table”.

Next, a table required when there are two types of measurement target tissues m (m ₁ , m ₂ ) is shown. Note that m ₁ and m ₂ are information indicating the type of tissue, such as subcutaneous tissue and muscle, respectively.

First, in the case of an organization where m ₁ is above m ₂ , a table of m _{1 and} a table of m ₂ are created as shown in Table 4 below.

Obtain whether the information indicating the type of tissue is m ₁ or m ₂ , obtain information indicating the hierarchical relationship of the organization indicating which of m ₁ and m ₂ is above, and A table corresponding to the information is used. In other words, when m ₁ is below m ₂ , information indicating the vertical relationship indicating that is obtained, and the table of m _{1 and} the table of m ₂ shown in Table 5 below are created. The reason for dividing the table used according to the hierarchical relationship in this way is that the elasticity index varies depending on whether the same type of tissue is above or below another tissue.

When the organization has three layers, a table is created in the same manner as described above. For example, if (i) m ₁ , m ₂₁ , m ₂₂ (m ₂₁ and m ₂₂ are the same type of tissue but have a two-layer structure), (ii) m ₁₁ , m ₁₂ , m ₂ (M ₁₁ and m ₁₂ have the same structure but have a two-layer structure), (iii) m ₁₁ , m ₂ and m ₁₂ (m ₁₁ and m ₁₂ represent m ₂ For example, a table corresponding to the type of each organization and the vertical relationship may be created. In the case of the same type of organization, the information indicating the type of organization may be managed by further associating the first and second identification information with the information indicating the type of organization being the same, and the layer information You may make it distinguishable. Thus, if a table is added according to the increase in the types of layers and tissues, elasticity indices corresponding to various tissues can be calculated. FIG. 5 shows an example of one layer of subcutaneous fat (m ₁ ) and two layers of muscle layers (m ₂₁ , m ₂₂ ).

  These tables may be created separately for each age, sex, person type, height, weight, etc.

In the present embodiment, the case where the above-described table is used will be described. However, the tissue 11 may be simplified by a one-dimensional spring and the Hooke's law may be applied. That is, the elasticity index may be calculated using the following mathematical formula.
F = −kΔx
Here, F is the pressing force, k is the elasticity index, and Δx is the amount of movement of the tissue.

In order to press the tissue 11 and obtain the elasticity index k,
k = −F / Δx
Should be calculated.

  Here, an example of evaluation of hardness (elasticity index) using the ultrasonic biological tissue measuring apparatus according to the present invention will be described with reference to FIGS.

  FIG. 5 is a diagram for explaining the processing of the analysis unit 3 of the ultrasonic biological tissue measurement apparatus 1. The characteristic diagram of the pressing force in the upper part of FIG. 5 shows how the pressing force is increased or decreased.

The middle image in FIG. 5 is an echo image (B mode), and the adjacent characteristic diagram (line diagram: A mode) represents the characteristic of the center dotted line in the echo image. Image 1 is an image acquired at a load of 150 gf at the 20 / 100th frame, and image 2 is an image acquired at a load of 4500 gf at the 90 / 100th frame. Symbols A, B, C, and D in the image image indicate vertex positions in the adjacent diagram. Symbols A, B, C, and D indicate A-mode characteristic positions where the luminance on the image changes. Specifically, A to B indicate subcutaneous fat, B to C indicate the first layer of muscle, and C to D indicate the second layer of muscle. The lower characteristic table shows the distance from the end points to positions A to D in image 1 and image 2, the difference between the value of image 1 and the value of image 2 (measurement value difference), and the rate of change (per unit area). The dimension is (N / m) or (m ³ / kg)). By applying the pressing force, the thickness from A to B, the thickness from B to C, and the thickness from C to D changed.

  FIG. 6 is a diagram showing the echo image and the position of the tissue layer. When an echo image of the human upper arm is acquired, the result is as shown in FIG. 6A, and when an echo image of the front thigh is acquired, the result is as shown in FIG. 6B.

  FIG. 7 is a diagram showing a change in thickness and thickness of the tissue when the pressing force is changed. When the pressing force was continuously changed as shown in FIG. 7 (a), the tissue site changed as shown in FIG. 7 (b). FIG. 7B is an echo image. Further, the interval table of each layer according to the change of the tissue site is as shown in FIG. 7C, and the change rate from the initial pressing force is as shown in the characteristic table of FIG. 7D.

  FIG. 8 is a graph showing a change rate characteristic table from the initial pressing force in FIG. 7D.

  FIG. 9 is a diagram schematically showing the expansion / contraction mode of each layer of the tissue when a pressing force is applied to the tissue. The layered structure can be modeled as a structure in which a plurality of springs are connected as shown in FIG. When a force F is applied thereto, the result is as shown in FIG. Each layer of tissue expands and contracts as a whole.

  FIG. 10 is a characteristic diagram of the elasticity index with respect to the pressing force of the BC layer and the CD layer of the tissue.

Generally, as shown in FIG. 8, the change in the thickness of the tissue with respect to the pressing force is not linear. This is a phenomenon called strain hardening in which the hardness of the tissue increases with the pressing force. Therefore, in order to obtain a constant index (independent of the pressing force) necessary for the evaluation of the structure, it is necessary to convert the pressing force with a certain function and perform linear approximation. When a function to be used is a natural logarithm (ln), F is a pressing force, k ′ is an elastic index, and Δx is a movement amount of tissue,
k ′ = − ln (F) / Δx
It is expressed. FIG. 10 is a graph obtained by calculating the elasticity index k ′ with respect to the pressing force F.

  As described above, in the present embodiment, the case where the ultrasonic transmission / reception unit 6, the pressing force reception unit 7, the tissue deformation amount detection unit 8 and the like are provided has been described. However, the ultrasonic biological tissue measurement apparatus according to the present invention is provided. However, it is not limited to such a configuration. The ultrasonic biological tissue measurement device according to the present invention is based on the measurement result received from the pressing force measurement unit and the elasticity of the measurement target tissue based on the change in the thickness of the measurement target tissue detected from the ultrasonic signal received by the ultrasonic probe. An elastic index calculation unit that calculates an index is provided, and the pressing force measurement unit may be a strain sensor or a pressure sensor.

[Example 1 of operation of ultrasonic biological tissue measuring apparatus 1]
Next, an example of the operation of the ultrasonic biological tissue measuring apparatus 1 will be described with reference to FIG. FIG. 11 is a flowchart showing an example of the operation of the ultrasonic biological tissue measuring apparatus 1.

  First, in the memory (recording unit), the elasticity index kt, the information indicating the type of the tissue 11, the change amount Δx of the tissue 11 due to the pressing force, the table indicating the relationship between the layer information n and the pressing force f, the window width w, the window Is stored (step S0), and then the process is started.

  Next, the ultrasonic transmission / reception unit 6 controls the ultrasonic probe 4 to emit ultrasonic waves according to the depth of the tissue 11 to the tissue 11. Then, an echo from the tissue 11 is received via the ultrasonic probe 4 to obtain a depth-luminance characteristic (1D and 2D) of the echo, and a signal indicating the depth-luminance characteristic (1D and 2D). Is output to the tissue deformation amount detection unit 8 and the display unit 10 (step S1).

  Next, the tissue deformation amount detection unit 8 generates a window having a window width w read from the memory from the memory with respect to the signal indicating the depth-luminance characteristics (one-dimensional and two-dimensional) received from the ultrasonic transmission / reception unit 6. The maximum value is calculated while shifting in the depth direction by the read movement interval, the curve of the maximum value is obtained, and the center position of the portion where the maximum value does not change even if the window is moved by the window width value is obtained. The tissue position is set (step S2).

  On the other hand, the pressing force receiving unit 7 receives the measured value F of the pressing force from the pressing force measuring sensor 5, and transmits it to the elasticity index calculating unit 9 (step S3).

  The elasticity index calculation unit 9 uses the change amount of the tissue position in a plurality of pressing forces as the change amount Δx of the tissue thickness, and stores the Δx and the pressing force F obtained from the pressing force receiving unit 7 in a memory. The elasticity index kt is calculated by applying it to the table read out from. At this time, the information indicating the type of the tissue 11 for which the elasticity index is calculated and the layer information are acquired by causing the input unit (not shown) to input the information, for example, by requesting the user to input. The acquisition of the information indicating the type of the tissue 11 and the layer information may be performed in advance before the processing by the elasticity index calculation unit 9, such as at the time of step S <b> 0, or in the process of being processed by the elasticity index calculation unit 9. The user may be requested and input. Next, the elasticity index calculation unit 9 transmits the calculated kt, Δx used for the calculation, and the pressing force F to the display unit 10 (step S4).

  Finally, the display unit 10 displays information indicating the depth-luminance characteristics (one-dimensional and two-dimensional) of the echo received from the ultrasonic transmission / reception unit 6, Δx received from the elastic index calculation unit 9, the pressing force F, and the elastic index kt. Display (step S5), and the process ends.

  As described above, according to the present invention, it is possible to easily obtain an index related to tissue hardness. In addition, according to the present invention, by improving the accuracy of ultrasonic measurement, even for soft tissues having a hierarchical structure with skin, fat, muscle, bone, etc. like body tissues, an elasticity index is provided for each hierarchy. It can be calculated.

[Example 2 of operation of ultrasonic biological tissue measuring apparatus 1]
Another example of the operation of the ultrasonic biological tissue measuring apparatus 1 will be described. In this example, the state of the tissue is determined by classifying by deformation by pressing, which differs depending on the type of subcutaneous tissue. For example, FIG. 12 shows correlation information between the thickness of subcutaneous fat and muscle and whether the subject falls into lymphedema. FIG. 12 is a diagram showing an example of state-thickness correlation information in the present invention. The thickness of the tissue to be measured before pressing the ultrasonic probe is plotted on the horizontal axis, and the initial subcutaneous fat thickness is obtained. Further, as an index including a change in the thickness of the tissue to be measured by pressing the ultrasonic probe, the vertical axis represents the change in subcutaneous fat thickness relative to the change in the rectus femoris muscle thickness. This is the thickness from A to B / the thickness from B to C in FIG. 5 (shown as “AB / BC” in FIG. 12). The state of the tissue 11 to be measured is an area to which the plot area of the graph of FIG. Region I and region II are groups without lymphedema cases, and region III and region IV are groups with lymphedema cases. In FIG. 12, the numbers enclosed in a square frame indicate the numbers of subjects. The error bar is calculated based on FIG. FIG. 13 is a diagram showing the relationship between the rectus femoral muscle thickness and the subcutaneous fat thickness for each subject. As shown in FIG. 13, the rectus femoris muscle thickness and subcutaneous fat thickness for each subject are plotted on a graph, and then linear regression is performed. The standard error calculated at that time is the error bar.

  The state-thickness correlation information shown in the graph of FIG. 12 may be stored in the memory or the like of the elasticity index calculation unit 9 or may be stored in an external recording medium.

  A change in the thickness of the tissue 11 is measured by the ultrasonic probe 4, and the measurement result is sent to the elasticity index calculation unit 9. The elasticity index calculation unit 9 determines the measured tissue 11 based on the state-thickness correlation information. The state of the tissue 11 corresponding to the change in thickness is determined. That is, the elasticity index calculation unit 9 determines which region of the regions I to IV the tissue 11 belongs to. The result of which region the tissue 11 belongs to is one of the elasticity indices. That is, the region to which the tissue 11 belongs can be referred to as an elasticity index of the tissue 11. This is because there is a correlation between whether or not there is a case and elasticity. The initial thickness of subcutaneous fat may be stored in advance in the memory of the elasticity index calculation unit 9 or an external recording medium.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  INDUSTRIAL APPLICABILITY The present invention can be used in fields that require non-invasive measurement of tissue hardness and softness, such as health care, agriculture (evaluation of meat quality), and fishery (evaluation of meat quality). . Further, since a large-scale device such as a moving mechanism is not necessary for the ultrasonic probe portion, it can be used as a portable device for carrying it not only indoors but also outdoors.

DESCRIPTION OF SYMBOLS 1 Ultrasonic biological tissue measuring apparatus 2,202,202 ', 202''Measuring part 3 Analyzing part 4,204, Ultrasonic probe 5 Pressing force measuring sensor (Pressing force measuring part, distortion sensor)
6 Ultrasonic Transmitting / Receiving Unit 7 Pushing Force Receiving Unit 8 Tissue Deformation Detection Unit 9 Elastic Index Calculation Unit 10 Display Unit 11 Tissue (Measurement Target Tissue)
204a End face 205 Pressing force measuring sensor (pressing force measuring unit, pressure sensor)
212 Housing 212a Opening

Claims (5)

An ultrasonic probe that emits ultrasonic waves to the measurement target tissue and receives ultrasonic waves reflected from the measurement target tissue; and
A pressing force measuring unit that measures the force pressing the ultrasonic probe against the tissue to be measured;
An elasticity index calculation unit,
The elasticity index calculation unit calculates the elasticity index of the measurement target tissue from the measurement result received from the pressing force measurement unit and the change in the thickness of the measurement target tissue detected from the ultrasonic signal received by the ultrasonic probe. Is,
The elasticity index calculation unit includes a preset elasticity index, a change in thickness of the measurement target tissue, a pressing force against the measurement target tissue, and a layer where the measurement target tissue has a layer structure. The elasticity index is calculated based on the measured change amount and the pressing force from the relationship information indicating the relationship with the information indicating
The pressing force measurement unit includes a strain sensor that measures distortion of the ultrasonic probe that occurs when the ultrasonic probe is pressed against a measurement target tissue, or the ultrasonic probe is stored in a housing, An ultrasonic biological tissue measurement device, which is a pressure sensor that measures a pressure generated when the ultrasonic probe is pressed against the housing when the ultrasonic probe is pressed against the measurement target tissue.   The ultrasonic biological tissue measurement apparatus according to claim 1, wherein the pressing force measurement unit is a strain sensor that measures distortion of the ultrasonic probe that occurs when the ultrasonic probe is pressed against a measurement target tissue. The ultrasonic probe is stored in a housing having an opening in a state where an end surface that presses against the measurement target tissue of the ultrasonic probe is exposed from the opening.
The pressing force measurement unit is a pressure sensor that measures a pressure generated when the ultrasonic probe is pressed against the housing when the ultrasonic probe is pressed against a measurement target tissue.
2. The ultrasonic biological body according to claim 1, wherein the pressure sensor is disposed between a surface of the ultrasonic probe and the casing on a line passing through the center of gravity of the end surface and perpendicular to the end surface. Tissue measuring device. The relationship information includes the elasticity index, the amount of change in the thickness of the measurement target tissue, the pressing force against the measurement target tissue, the information indicating which layer when the measurement target tissue has a layer structure, and the measurement The ultrasonic biological tissue measuring device according to any one of claims 1 to 3 , which is information indicating a relationship with information indicating a type of a target tissue.   The elasticity index calculation unit calculates the relationship between the thickness of the measurement target tissue before pressing the ultrasonic probe, the index including the change in the thickness of the measurement target tissue by pressing the ultrasonic probe, and the state of the measurement target tissue. Measurement target tissue state determination for determining the state of the measurement target tissue, which is the elastic index, based on the change in thickness of the measurement target tissue measured by pressing the ultrasonic probe from the state-thickness correlation information to be shown The ultrasonic biological tissue measuring apparatus according to claim 1, further comprising means.