JP6243719B2 - Biological blood vessel state measurement device - Google Patents

Description

  The present invention relates to a biological blood vessel state measuring apparatus for measuring the state of a blood vessel based on an ultrasonic reflection signal with respect to a part of blood vessels of a living body, and more particularly to an improvement for facilitating measurement.

  A living body in which an ultrasonic sensor is brought into contact with a living body, ultrasonic waves are radiated to a blood vessel located under the epidermis, and a state of a blood vessel diameter, a lumen diameter, etc. of the blood vessel is measured based on a reflected signal of the ultrasonic wave A blood vessel state measuring device is known. The measurement of the blood vessel state by this biological blood vessel state measuring device is, for example, a time difference process between ultrasonic reflection signals reflected from their boundaries due to a difference in propagation speed between the blood vessel and another tissue, or a combination of the reflection signals. This is performed by distance measurement on an ultrasonic image.

  A technique for improving the measurement accuracy of the blood vessel state by the biological blood vessel state measuring device has been proposed. For example, the blood vessel shape measuring apparatus described in Patent Document 1 is an example. According to this technique, the cross-sectional shape of the blood vessel is calculated based on an ultrasonic reflection signal with respect to some blood vessels of the living body, and the central axis of the blood vessel is calculated based on the center point of the cross-section of the blood vessel wall in the cross-sectional shape. By calculating, it is possible to measure the shape of the blood vessel, the blood flow velocity and the blood flow in the blood vessel with high accuracy.

Japanese Patent No. 4444164

  However, the conventional technique may not always accurately identify the center point of the blood vessel. That is, the process of simply calculating the center point of the cross section of the blood vessel wall in the cross-sectional shape of the blood vessel is likely to cause an error, and development of a method for identifying the central position of the blood vessel more accurately has been demanded. If the center position of the blood vessel to be measured cannot be identified, for example, the center depth of the short-axis blood vessel images upstream and downstream of the blood vessel cannot be aligned, and as a result, a horizontal long-axis image cannot be extracted. Bad effects occur. In addition, the blood vessel repeatedly branches and becomes narrower as it goes to the peripheral side, but it becomes difficult to measure at the branch portion of the blood vessel. That is, the present situation is that a biological blood vessel state measuring apparatus that appropriately identifies the central position of the blood vessel to be measured and facilitates the measurement has not yet been developed.

  The present invention has been made against the background of the above circumstances, and an object of the present invention is to provide a blood vessel shape measuring apparatus that facilitates measurement.

In order to achieve such an object, the gist of the first invention is that an ultrasonic wave is radiated to a blood vessel located in the epidermis of a living body, and the state of the blood vessel is based on the reflected signal of the ultrasonic wave. A biological blood vessel state measuring apparatus for measuring a short-axis cross-sectional shape calculation unit for calculating a short-axis cross-sectional shape of the blood vessel based on the reflection signal, and the short axis calculated by the short-axis cross-sectional shape calculation unit boundary point extracting unit that extracts at random at least three boundary points on the cross-sectional shape boundary, the center in the short-axis cross-sectional shape based on the at least three boundary points extracted by the boundary point extracting section a center coordinate estimating unit for estimating the coordinates, and extraction of said at least three boundary points by the boundary point extracting unit, which is extracted in said at least three of said center coordinates by the center coordinate estimating unit based on the boundary point And a center position identifying unit that identifies the center position in the short-axis cross-sectional shape based on the average of the estimation results of the center coordinates of the plurality of times. Is.

According to the first invention, a short-axis cross-sectional shape calculation unit that calculates a short-axis cross-sectional shape of the blood vessel based on the reflected signal, and a boundary between the short-axis cross-sectional shapes calculated by the short-axis cross-sectional shape calculation unit estimating the center coordinates in the short-axis cross-sectional shape based on at least three boundary point extracting unit that extracts a random boundary points, said at least three boundary points extracted by the boundary point extracting unit on It repeats the center coordinate estimation unit, the extraction of the at least three boundary points by the boundary point extraction unit, and the estimation of the center coordinates by the center coordinate estimation unit based on the extracted at least three boundary points A plurality of times, and based on the average of the estimation results of the center coordinates of the plurality of times, a center position identifying unit for identifying the center position in the short-axis cross-sectional shape, By identifying the estimation result to the center position in the short-axis cross-sectional shape on the basis, it is possible to identify more precisely such a central position by suppressing the influence of the error. That is, it is possible to provide a blood vessel shape measuring device that facilitates measurement.

The gist of the second invention subordinate to the first invention is that the at least three boundary points are extracted by the boundary point extracting unit, and the central coordinates based on the extracted at least three boundary points. The estimation of the center coordinates by the estimation unit is repeatedly performed a plurality of times, and the short-axis cross-sectional shape corresponds to the branch portion of the blood vessel based on the degree of dispersion of the estimation results of the center coordinates a plurality of times. A blood vessel branch determination unit for determining whether or not. In this way, the measurement by the blood vessel shape measuring device can be made easier by avoiding the bifurcation where the measurement of the blood vessel state is difficult.

  The gist of the third invention subordinate to the second invention is that the short-axis cross-sectional shape is determined by a probe that radiates ultrasonic waves to a blood vessel located in the epidermis of a living body and the blood vessel branch determination unit. And a probe movement control unit that relatively moves the probe so as to be separated from the branch when it is determined to correspond to the branch of the blood vessel. In this way, it is possible to avoid a bifurcation that makes it difficult to measure the blood vessel state in a suitable and practical manner.

  The gist of the fourth invention subordinate to the second invention is that the short-axis cross-sectional shape is determined by a probe that radiates an ultrasonic wave to a blood vessel located in the epidermis of a living body and the blood vessel branch determination unit. When it is determined that the blood vessel corresponds to the branching portion of the blood vessel, a probe movement notification unit that performs notification for urging the relative movement of the probe is provided. In this way, it is possible to avoid a bifurcation that makes it difficult to measure the blood vessel state in a suitable and practical manner.

The gist of the fifth invention according to any one of the first to fourth inventions is that the central coordinate estimating unit includes the at least three boundary points extracted by the boundary point extracting unit. An approximate circle is created, and the center coordinate of the approximate circle is estimated as the center coordinate in the short-axis cross-sectional shape. In this way, the center coordinates in the short-axis cross-sectional shape can be estimated in a suitable and practical manner.

  The gist of the present invention according to any one of the first invention to the fifth invention is that the region including the short-axis cross-sectional shape calculated by the short-axis cross-sectional shape calculating section is divided into a plurality of areas. An estimated central coordinate recording unit that records which of the plurality of sections includes the estimated central coordinate every time the central coordinate is estimated by the central coordinate estimating unit; and After the center coordinates are estimated by the center coordinate estimation unit a plurality of times, an average value of the estimation results of the center coordinates included in the section in which the maximum number of center coordinates is recorded by the estimated center coordinate recording unit, It is identified as the center position in the short-axis cross-sectional shape. In this way, the center position in the short-axis cross-sectional shape can be identified in a suitable and practical manner.

It is a perspective view which illustrates the whole structure of the biological blood vessel state measuring apparatus which is one Example of this invention. It is a figure explaining the xyz-axis orthogonal coordinate axis | shaft used in a present Example regarding the positioning of the ultrasonic probe in the biological blood vessel state measuring apparatus of FIG. It is an enlarged view which shows roughly the multilayer film structure of the blood vessel which is a measuring object of the biological blood vessel state measuring apparatus of FIG. It is a figure which illustrates the ultrasonic image of the blood vessel displayed on a monitor screen display apparatus in the measurement of the blood vessel state by the biological blood vessel state measuring apparatus of FIG. 2 is a time chart illustrating the change in the diameter of a blood vessel lumen after release of ischemia in the blood vessel FMD evaluation by the biological blood vessel state measurement apparatus of FIG. 1. It is a functional block diagram explaining the principal part of an example of the control function with which the biological blood vessel state measuring apparatus of FIG. 1 was equipped. 2 shows an example of an image including a short-axis image of a blood vessel generated by the biological blood vessel state measurement apparatus of FIG. A two-gradation image obtained by gradationizing the image shown in FIG. 7 is illustrated. It is a figure explaining the image differentiation which concerns on the image shown in FIG. It is a figure which illustrates the boundary line in the short-axis cross-sectional shape of the blood vessel contained in the image determined regarding the image shown in FIG. It is a figure explaining the extraction of the boundary point in the short-axis cross-sectional shape of the blood vessel by the biological blood-vessel state measuring apparatus of FIG. 1, creation of an approximate circle, and estimation of a center coordinate. It is a figure explaining the setting of the grid in the area | region containing the short-axis cross-sectional shape of the blood vessel by the biological vascular state measuring apparatus of FIG. It is a figure explaining the identification of the center position of the short-axis cross-sectional shape of the blood vessel by the biological blood vessel state measuring apparatus of FIG. It is a figure explaining the determination of the branch part based on the short-axis cross-sectional shape of the blood vessel by the biological blood vessel state measuring apparatus of FIG. It is a figure which illustrates the short-axis image and long-axis image corresponding to the blood vessel corresponding to the part which is not a branch part displayed on the monitor screen display apparatus in the biological blood-vessel state measuring apparatus of FIG. It is a figure which illustrates the short-axis image and long-axis image corresponding to the blood vessel corresponded to the branch part displayed on the monitor screen display apparatus in the biological blood-vessel state measuring apparatus of FIG. It is a flowchart explaining the principal part of an example of the vascular state evaluation control by the electronic controller with which the biological vascular state measuring apparatus of FIG. 1 was equipped.

  The blood vessel shape measuring apparatus of the present invention preferably measures the brachial artery, which is an artery in the upper arm epidermis of a living body. Alternatively, the present invention is similarly applied to the measurement of blood vessel parameters such as arteries and veins that can be measured from the epidermis surface such as the forearm portion of the living body and the tibia artery, and blood vessels of other lower limbs, and has an effect.

  The probe provided in the blood vessel shape measuring apparatus of the present invention is preferably composed of two parallel arrays of the first short axis ultrasonic array probe and the second short axis ultrasonic array probe. This is an H-type hybrid type ultrasonic probe having a long-axis ultrasonic array probe connecting the central portions in the longitudinal direction on one plane. Alternatively, the present invention is similarly applied to a blood vessel shape measuring apparatus provided with an inline type or other probe, and there is an effect.

  The blood vessel shape measuring apparatus of the present invention preferably includes an ultrasonic probe having three ultrasonic array probes, but two ultrasonic array probes or four or more ultrasonic arrays. The present invention is also suitably applied to a biological blood vessel state measuring apparatus provided with an ultrasonic probe having a probe.

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

  FIG. 1 shows a probe unit 12 held in a sensor holder 10, and a non-vascularization of a blood vessel 20 such as an artery located directly below the skin 18 from the top of the skin 18 (strictly the epidermis) in the upper arm 16 of the living body 14. It is a perspective view which illustrates the whole structure of the biological blood-vessel state measuring apparatus 22 (henceforth only the measuring apparatus 22) which is one Example of this invention which performs invasive ultrasonic diagnosis.

The probe unit 12 functions as a sensor for detecting biological information related to the blood vessel 20, that is, a blood vessel parameter, and includes a pair of first short-axis ultrasonic array probes 24a parallel to each other, and An H-type having a second short-axis ultrasonic array probe 24b and a long-axis ultrasonic array probe 24c connecting the central portions in the longitudinal direction on a flat probe surface 25 on one plane. The ultrasonic probe 24 is provided. The probe unit 12 includes a multi-axis drive device (positioning device) 26 that positions the ultrasonic probe 24 in the xyz direction and positions rotation angles about the x-axis and the z-axis. The first short axis ultrasonic array probe 24a, the second short axis ultrasonic array probe 24b, and the long axis ultrasonic array probe 24c are, for example, as shown in FIG. are configured respectively in the longitudinal shape by the piezoelectric ceramic number composed of numbers of ultrasonic transducers (ultrasonic oscillators) a ₁ ~a _n are linearly arranged.

  FIG. 2 is a diagram for explaining xyz-axis orthogonal coordinate axes used in the present embodiment with respect to positioning of the ultrasonic probe 24. In FIG. 2, the blood vessel 20 or the vicinity thereof is positioned in parallel with the longitudinal direction of the first short axis ultrasonic array probe 24a and directly below the first short axis ultrasonic array probe 24a. The passing direction is the x-axis. Further, the direction parallel to the longitudinal direction of the long-axis ultrasonic array probe 24c and orthogonal to the x-axis is taken as the y-axis. Further, it passes through the intersection of the longitudinal direction of the first short-axis ultrasonic array probe 24a and the longitudinal direction of the long-axis ultrasonic array probe 24c and is orthogonal to the x-axis direction and the y-axis direction. The direction is the z-axis. With respect to the xyz-axis orthogonal coordinate axes as shown in FIG. 2, the ultrasonic probe 24 is translated in the x-axis direction by the multi-axis driving device 26, for example. Further, it is rotated around the x axis and the z axis.

FIG. 3 is an enlarged view schematically showing the multilayer film configuration of the blood vessel 20 that is the measurement target of the measurement device 22. The blood vessel 20 shown in FIG. 3 is preferably a brachial artery, and has a three-layer structure of an intima L ₁ , a media L ₂ , and an adventitia L ₃ . Since reflection of ultrasonic waves generally occurs at different parts of acoustic impedance, in the measurement of the state of the blood vessel 20 using ultrasonic waves, the boundary surface between the blood in the blood vessel lumen and the intima L ₁ and the medium are actually used. The boundary surface between the membrane L ₂ and the outer membrane L ₃ is displayed in white, and the tissue is displayed in black and white.

  As shown in FIG. 1, the measuring device 22 includes an electronic control device 28 composed of a so-called microcomputer having a CPU that processes an input signal in accordance with a program stored in the ROM in advance using the temporary storage function of the RAM. A monitor screen display device (image display device) 30, an ultrasonic drive control circuit 32, and a triaxial drive motor control circuit 34. In the measurement of the blood vessel state by the measurement device 22, when a drive signal is supplied from the ultrasonic drive control circuit 32 by the electronic control device 28, the first short axis of the ultrasonic probe 24 in the probe unit 12. Ultrasonic array probe 24a, second short axis ultrasonic array probe 24b, and long axis ultrasonic array probe 24c generate beam-like ultrasonic waves by well-known beam forming drive. Sequentially emitted. Then, an ultrasonic reflected signal is detected by the first short axis ultrasonic array probe 24a, the second short axis ultrasonic array probe 24b, and the long axis ultrasonic array probe 24c. Then, processing of the detected ultrasonic reflection signal is performed in the electronic control device 28, so that an ultrasonic image under the skin 18 is generated and displayed on the monitor screen display device 30.

  As shown in FIG. 1, the measurement apparatus 22 includes an ultrasonic drive control unit 80, a detection processing unit 82, an ultrasonic signal processing unit 84, a triaxial drive motor control unit 86, a cuff pressure control unit 88, and a blood vessel state evaluation unit. 90, and a display control unit 92. These control functions are preferably functionally provided in the electronic control device 28, but a part or all of these control functions are separate from the electronic control device 28. And may perform control described in detail below by mutually communicating information.

  FIG. 4 shows the positional relationship between the ultrasound probe 24 and the blood vessel 20 positioned at a predetermined measurement position when an ultrasound image of the blood vessel 20 is generated in the measurement of the blood vessel state by the measurement device 22. It is a figure which shows and illustrates the ultrasonic image of the blood vessel displayed on the said monitor screen display apparatus 30 in such a positional relationship. For example, as shown in FIG. 4A, the monitor screen display device 30 is configured to display an ultrasonic image (first image) corresponding to an ultrasonic reflection signal detected by the first short-axis ultrasonic array probe 24a. An ultrasonic image (second short-axis image) corresponding to an ultrasonic reflection signal detected by the first short-axis image display region G1 displaying the short-axis image) and the second short-axis ultrasonic array probe 24b. ) And an ultrasonic image (long axis image, blood vessel longitudinal section image) corresponding to the ultrasonic reflection signal detected by the long axis ultrasonic array probe 24c. A long-axis image display area G3 to be displayed. Preferably, the first short-axis image display area G1, the second short-axis image display area G2, and the long-axis image display area G3 have a common vertical axis indicating a depth dimension from the skin 18. Is. In addition, “ImA, ImB” in FIG. 4A indicates a transverse section of the blood vessel 20, respectively.

  The measuring device 22 preferably has a diameter, inner film thickness, plaque, blood flow velocity, etc. of the blood vessel 20 based on an ultrasonic reflection signal output from the ultrasonic probe 24 to the blood vessel 20. FMD (Flow-Mediated Dilation) that measures blood flow is evaluated. When evaluating the FMD, the monitor screen display device 30 displays, for example, the rate of change of the intima diameter in the blood vessel 20, that is, the lumen diameter expansion rate R in time series. When the FMD is evaluated and an ultrasonic image of the blood vessel 20 is generated, the ultrasonic probe 24 is placed in the electronic control unit 28 so that the ultrasonic probe 24 is at a predetermined measurement position P with respect to the blood vessel 20 to be measured. Positioning is performed by driving the multi-axis driving device 26 supplied with a driving signal from the three-axis driving motor control circuit 34 by the provided three-axis driving motor control unit 86. The predetermined measurement position P is preferably such that the first short axis ultrasonic array probe 24a and the second short axis ultrasonic array probe 24b are orthogonal to the blood vessel 20, The long axis ultrasonic array probe 24 c is parallel to the blood vessel 20. Referring to FIG. 4, the predetermined measurement position P is a position where “a = b, c = d, e = f” in FIG. That is, the distance from the first short-axis ultrasonic array probe 24a to the center of the blood vessel 20 and the distance from the second short-axis ultrasonic array probe 24b to the center of the blood vessel 20 are mutually different. It is the measurement position where the image of the blood vessel 20 is located at the center in the width direction in both the first short-axis image display region G1 and the second short-axis image display region G2.

  In the measurement of the blood vessel state by the measurement device 22, the sensor holder 10 is in a state in which the blood vessel 20 positioned immediately below the skin 18 of the upper arm 16 in the living body 14 is lightly contacted so as not to deform. The probe unit 12 is held in a desired posture. Preferably, the probe unit 12 is held in a desired posture so that the position of the ultrasonic probe 24 in the three-dimensional space is the predetermined measurement position P with respect to the blood vessel 20. Preferably, between the end face of the ultrasonic probe 24 and the skin 18 in the probe unit 12, the attenuation of the ultrasonic wave, the reflection and scattering at the boundary surface are suppressed, and the ultrasonic image is made clear. Well-known coupling agents such as jelly, olive oil and glycerin, water bags in which water is confined in a resin bag, and the like are interposed.

  As shown in FIG. 1, the sensor holder 10 includes, for example, a magnet base 36 that is fixed to a desk, a pedestal, or the like by magnetic attraction, a unit fixture 38 to which the probe unit 12 is fixed, and the magnet. Connecting members 44 and 45 each having one end fixed to the base 36 and the unit fixture 38 and having a tip 42 formed in a spherical shape, and the magnet base 36 and the unit fixture 38 via the connecting members 44 and 45. And a universal arm 40 that is connected and supported so as to be relatively movable. The universal arm 40 includes two links 46 and 47 that are pivotably connected to each other, and a fitting that is rotatably fitted to the distal end portion 42 at one end of the links 46 and 47. The curved joint portions 50 and 51 each having a hole 48 and the other ends of the links 46 and 47 are connected to the other ends of the links 46 and 47 so as to be capable of relative rotation with each other and screwed into screw holes extending through the connecting portions. And a rotary joint portion 54 that is made relatively non-rotatable by a fastening force obtained by tightening the fixed knob 52 with the male thread.

  The multi-axis drive device 26 is, for example, an x-axis rotation (yaw) fixed to the unit fixture 38 in order to position the rotation position of the ultrasonic probe 24 around the x-axis by an x-axis rotation actuator. A mechanism, an x-axis translation mechanism for positioning the translation position of the ultrasonic probe 24 in the x-axis direction by the x-axis rotation actuator, and a rotation position of the ultrasonic probe 24 around the z-axis by the z-axis actuator. And a z-axis rotation mechanism for positioning. With such a configuration, the multi-axis drive device 26 controls the positioning state of the ultrasonic probe 24 in accordance with a command from the electronic control device 28.

The ultrasonic drive control circuit 32 controls the emission of ultrasonic waves from the ultrasonic probe 24 to the blood vessel 20 according to a command from an ultrasonic drive control unit 80 provided in the electronic control device 28. For example, the plurality of which are arranged in a row in the first ultrasonic detector array 24a for the minor axis of the ultrasonic transducer a ₁ to a _n, a certain number from the ultrasonic transducer a ₁ of the end A group of ultrasonic transducers, for example, a beam forming drive that simultaneously drives at a frequency of about 10 MHz while giving a predetermined phase difference to each of ₁₅ a _{1 to} a ₁₅ , thereby achieving super-convergence in the arrangement direction of the ultrasonic transducers. A sound beam is sequentially emitted toward the blood vessel 20. Then, a reflected wave for each radiation when the ultrasonic beam is scanned while scanning the ultrasonic transducers one by one is received and input to the electronic control unit 28. The reflected wave signal input to the electronic control unit 28 is detected by the detection processing unit 82 and processed by the ultrasonic signal processing unit 84 as information that can be combined as described in detail below. The ultrasonic signal processing unit 84 performs, for example, time difference processing between ultrasonic reflection signals reflected from their boundaries due to a difference in propagation velocity between the blood vessel 20 and other tissues, and an ultrasonic image based on the reflection signals. Perform synthesis processing.

The electronic control unit 28 synthesizes an image based on the reflected wave of the ultrasonic wave received by the ultrasonic probe 24, and forms a short-axis image, that is, a cross-sectional image, and a long-axis image of the blood vessel 20 under the skin 18. An image, that is, a longitudinal section image is generated and displayed on the monitor screen display device (image display device) 30. In addition, from the short-axis image and the long-axis image of the blood vessel 20 generated as described above, the diameter of the blood vessel 20 or the endothelium diameter (lumen diameter) d ₁ that is the diameter of the endothelium 70 is calculated. Further, in order to evaluate the endothelial function of the blood vessel 20, the expansion rate (change rate) R (%) of the blood vessel lumen diameter representing FMD (blood flow-dependent vasodilatation reaction) after ischemic reactive hyperemia. 100 × (d ₁ −d _a ) / d _a ] is calculated. “D _a ” in this equation indicates the diameter of the blood vessel lumen (base diameter, rest diameter) at rest.

  In the measurement of the blood vessel state by the measurement device 22, the measurement site in the living body 14, for example, the upper arm 16 is pressed by a pressurizing device such as a cuff 62 to block the blood flow, and a part of the living body 14 (peripheral rather than the ischemic part). The blood flow is rapidly released and the blood flow of the blood vessel 20 at the measurement site is rapidly increased, so that the blood flow from the endothelium accompanying the increase in shear stress to the blood vessel wall is increased. The production of nitric oxide (NO) occurs, and the endothelial function is determined by examining the relaxed state of smooth muscle depending on the nitric oxide.

FIG. 5 is a time chart illustrating the change in the vascular lumen diameter d ₁ after release of ischemia (blood transfer) in the FMD evaluation of the blood vessel 20 by the measuring device 22. In FIG. 5, the time point t1 represents the time when the ischemia is released, the blood vessel lumen diameter d ₁ starts to expand from the time point t2, and the blood vessel lumen diameter d ₁ reaches its maximum value d _MAX at the time point t3. It has been shown. Therefore, the expansion rate R of the blood vessel lumen diameter calculated by the electronic control device 28 becomes maximum at time t3.

The ischemia for FMD evaluation of the blood vessel 20 by the measuring device 22 is performed by an air pump 58, a pressure control valve 60, and the like by a cuff pressure control unit 88 provided in the electronic control device 28 as shown in FIG. It is executed by being controlled. For example, according to a command from the electronic control unit 28, the original pressure from the air pump 58 is controlled by the pressure control valve 60 and supplied to the cuff 62 wound around the upper arm 16. Specifically, the ischemia for FMD evaluation is performed by increasing the pressure (cuff pressure) of the cuff 62 to a predetermined ischemic cuff pressure that exceeds the maximum blood pressure of the living body 14. At this time, the cuff pressure control unit 88 detects the cuff pressure according to a signal from the pressure sensor 64 that detects the pressure (cuff pressure) of the cuff 62. In FIG. 5, for example, the cuff pressure control unit 88 maintains the cuff pressure at the ischemic cuff pressure for a predetermined time before the release of the ischemia, that is, a predetermined time before the time t1, and when the ischemia is released (time t1). The cuff pressure is immediately reduced to atmospheric pressure. As a result, the blood vessel 20 at the measurement site P is rapidly congested, and the measurement device 22 measures the blood vessel diameter d _max after the confusion of the target blood vessel 20 from the ischemic state.

  FIG. 6 is a functional block diagram for explaining a main part of an example of a control function provided in the blood vessel state evaluation unit 90. The blood vessel state evaluation unit 90 is configured to output ultrasonic waves emitted from the ultrasonic probe 24 to the blood vessel 20 located in the epidermis of the living body 14 by the ultrasonic drive control circuit 32 (ultrasonic drive control unit 80). On the other hand, the state of the blood vessel 20 is determined based on the reflected signal of the ultrasonic wave received by the ultrasonic probe 24 and subjected to detection by the detection processing unit 82 and signal processing by the ultrasonic signal processing unit 84. To evaluate. In order to perform such control, the blood vessel state evaluation unit 90 includes a short-axis cross-sectional shape calculation unit 100, a long-axis cross-sectional shape calculation unit 102, a boundary point extraction unit 104, a central coordinate estimation unit 106, and an estimated central coordinate recording unit 108. A central position identification unit 110, a blood vessel branch determination unit 112, a probe movement control unit 114, and a probe movement notification unit 116. Hereinafter, the processing of each control unit will be described in detail.

  The short-axis cross-sectional shape calculation unit 100 calculates the short-axis cross-sectional shape of the blood vessel 20 based on the reflected signal received by the ultrasonic probe 24. That is, the ultrasonic signal is received by the first short axis ultrasonic array probe 24a corresponding to the ultrasonic wave radiated from the first short axis ultrasonic array probe 24a, and is received by the ultrasonic signal processing unit 86. Based on the signal-processed reflection signal, the first short-axis cross-sectional shape of the blood vessel 20 corresponding to the reflection signal is calculated. The display control unit 92 displays a first short-axis image corresponding to the first short-axis cross-sectional shape calculated by the short-axis cross-sectional shape calculation unit 100 in the first short-axis image display area in the monitor screen display device 30. Display on G1. Further, the ultrasonic signal is received by the second short axis ultrasonic array probe 24b corresponding to the ultrasonic wave radiated from the second short axis ultrasonic array probe 24b, and is received by the ultrasonic signal processing unit 86. Based on the reflected signal subjected to signal processing, the second short-axis cross-sectional shape of the blood vessel 20 corresponding to the reflected signal is calculated. The display control unit 92 displays the second short-axis image corresponding to the second short-axis cross-sectional shape calculated by the short-axis cross-sectional shape calculation unit 100 in the second short-axis image display area in the monitor screen display device 30. Display on G2.

  The long-axis cross-sectional shape calculation unit 102 calculates the long-axis cross-sectional shape of the blood vessel 20 based on the reflected signal received by the ultrasonic probe 24. That is, in response to the ultrasonic wave emitted from the long-axis ultrasonic array probe 24 c, the ultrasonic signal is received by the long-axis ultrasonic array probe 24 c and processed by the ultrasonic signal processing unit 86. Based on the reflection signal, the long-axis cross-sectional shape of the blood vessel 20 corresponding to the reflection signal is calculated. The display control unit 92 displays a long-axis image corresponding to the long-axis cross-sectional shape calculated by the long-axis cross-sectional shape calculation unit 102 in the long-axis image display region G3 in the monitor screen display device 30.

  The boundary point extraction unit 104 determines (extracts) a boundary in the short-axis cross-sectional shape of the blood vessel 20 calculated by the short-axis cross-sectional shape calculation unit 100. The boundary in the short-axis cross-sectional shape of the blood vessel 20 is preferably a boundary between a blood vessel lumen and a wall in the blood vessel 20, but does not necessarily correspond to such a portion, and at least the blood vessel This corresponds to a boundary line (boundary edge) that can distinguish 20 short-axis cross-sectional shapes from other portions. The short-axis cross-sectional shape calculation unit 100 preferably determines the boundary of the short-axis cross-sectional shape of the blood vessel 20 using well-known image processing such as image enhancement and image differentiation. Do. For example, image enhancement processing that removes noise in the image, such as a two-gradation of the short-axis cross-sectional shape of the blood vessel 20 (processing that converts pixels brighter than the threshold into white and pixels darker than the threshold into black according to lightness) I do. Then, a differential value of luminance in the direction of 360 ° is calculated from the center position of the portion estimated to correspond to the short-axis cross-sectional shape of the blood vessel 20, and a position where the change is large (a position where the differential value is equal to or greater than a specified value). Is detected. The boundary point extraction unit 104 determines a portion corresponding to the short-axis cross-sectional shape of the blood vessel 20 as described above.

  An example of boundary determination in the short-axis cross-sectional shape of the blood vessel 20 by the boundary point extraction unit 104 will be described with reference to FIGS. FIG. 7 shows the ultrasonic signal processing unit received by the first short-axis ultrasonic array probe 24a corresponding to the ultrasonic waves emitted from the first short-axis ultrasonic array probe 24a. 8 shows an example of an image 120 generated based on the reflection signal that has been signal-processed by H.86. When the image 120 shown in FIG. 7 has two gradations, a two-gradation image 122 with a clear contrast is obtained as shown in FIG. In the two-gradation image 122 shown in FIG. 8, it is estimated that a substantially circular portion having a predetermined area corresponds to the short-axis cross-sectional shape of the blood vessel 20. With respect to such a portion, as shown in FIG. 9, a differential value of luminance in the direction of 360 ° from the center position is calculated, and a position with a large change (a position where the differential value is equal to or greater than a specified value) is detected. The position where the change is large is the position where the luminance appears large, and corresponds to the position of the vascular tissue (wall). As described above, for example, as indicated by a white broken line in FIG. 10, a part of the image 120 generated based on the reflected signal is determined as the boundary line 124 of the short-axis cross-sectional shape of the blood vessel 20.

  The boundary point extraction unit 104 preferably randomly extracts a plurality of boundary points on the boundary of the short-axis cross-sectional shape of the blood vessel 20 calculated by the short-axis cross-sectional shape calculation unit 100. For example, as shown in FIG. 11, boundary points 126a, 126b, 126c which are a plurality of (for example, three) points on the boundary line 124 of the short-axis cross-sectional shape of the blood vessel 20 (hereinafter, unless otherwise distinguished) The boundary points 126 are simply extracted at random.

  The center coordinate estimation unit 106 estimates center coordinates in the short-axis cross-sectional shape based on the short-axis cross-sectional shape boundary of the blood vessel 20 extracted by the boundary point extraction unit 104. Preferably, center coordinates in the short-axis cross-sectional shape are estimated based on a plurality of boundary points 126 extracted by the boundary point extraction unit 104. Preferably, as shown in FIG. 11, an approximate circle 128 (indicated by a one-dot chain line in FIG. 11) that includes the plurality of boundary points 126 extracted by the boundary point extraction unit 104 is created and approximated. The center coordinate of the circle 128 is estimated as the center coordinate 130 in the short-axis cross-sectional shape. Here, the approximate circle 128 including the plurality of boundary points 126 corresponds to a figure in which the plurality of boundary points 126 are points on the approximate circle 128, and is preferably a perfect circle. It may be non-circular. The center coordinate of the approximate circle 128 is the center when the approximate circle 128 is a perfect circle, but corresponds to the center of gravity when the approximate circle 128 is non-circular.

  The estimated center coordinate recording unit 108 records the center coordinate 130 in the short-axis cross-sectional shape estimated by the center coordinate estimating unit 106. Preferably, the region including the short-axis cross-sectional shape calculated by the short-axis cross-sectional shape calculation unit 100 is divided into a plurality of regions, and is estimated every time the central coordinate 130 is estimated by the central coordinate estimation unit 106. It is recorded which of the plurality of sections the center coordinate 130 is included in. FIG. 12 is a diagram illustrating an example of a grid (grid; grid, grid, grid) 132 that divides the region including the short-axis cross-sectional shape calculated by the short-axis cross-sectional shape calculation unit 100 into a plurality of regions. As shown in FIG. 12, the estimated center coordinate recording unit 108 is calculated by the short-axis cross-sectional shape calculation unit 100 in an image based on the reflection signal signal-processed by the ultrasonic signal processing unit 86, for example. Each time the center coordinate 130 is estimated by the center coordinate estimation unit 106, a grid 132 that divides the region including the short-axis cross-sectional shape into a plurality of regions is set (formed). The grid 132 is recorded on the set area. At least the estimated center coordinate 130 is stored in which of the sections (squares) in the grid 132.

  The center position identification unit 110 extracts the plurality of boundary points 126 by the boundary point extraction unit 104, and estimates the center coordinates 130 by the center coordinate estimation unit 106 based on the extracted boundary points 126. Is repeated a plurality of times, and the center position in the short-axis cross-sectional shape is identified based on the average of the estimation results of the center coordinates 130 of the plurality of times. The center position in the short-axis cross-sectional shape corresponds to the center in the short-axis cross section of the blood vessel 20 corresponding to the short-axis cross-sectional shape. In other words, it corresponds to the axial center of the blood vessel 20.

  Preferably, the central position identification unit 110 records the maximum number of central coordinates 130 by the estimated central coordinate recording unit 104 after the central coordinate estimation unit 104 has performed estimation of the central coordinate 130 a plurality of times. The average value of the estimation results of the center coordinates 130 included in the determined section is identified as the center position in the short-axis cross-sectional shape. For example, as shown in FIG. 13, after the center coordinate estimation unit 104 has estimated N times (for example, 100 times) of the center coordinates 130 (represented by white circles in FIG. 13), the estimated center An average value of a plurality of center coordinates 130 included in the grid 132 (the grid in the grid 132) where the largest number of center coordinates 130 are recorded by the coordinate recording unit 104 is used as a center position 134 (FIG. 13) in the short-axis cross-sectional shape. Is identified by a black circle). The average value of the plurality of center coordinates 130 is a coordinate corresponding to the average of the distribution of the plurality of center coordinates 130.

  The center position identification unit 110 preferably has a first short-axis cross-sectional shape corresponding to the reflected signal detected by the first short-axis ultrasonic array probe 24a and the second short-axis super-axis. For each second short-axis cross-sectional shape corresponding to the reflected signal detected by the acoustic wave array probe 24b, the center position 134 in each short-axis cross-sectional shape is identified by the above processing. The display control unit 92 preferably uses the first short-axis image based on the central position 134 in each of the first short-axis cross-sectional shape and the second short-axis cross-sectional shape identified by the central position identifying unit 110. Display control is performed so that the heights of the first short-axis cross-sectional image and the second short-axis cross-sectional image in the display area G1 and the second short-axis image display area G2 are substantially the same. Preferably, in each of the first short-axis image display region G1 and the second short-axis image display region G2, the center position 134 of each of the first short-axis cross-sectional image and the second short-axis cross-sectional image is the center of each display region. Display control is performed so that For example, as shown in FIG. 4 described above, the distance from the first short axis ultrasonic array probe 24a to the center of the blood vessel 20 and the second short axis ultrasonic array probe 24b to the blood vessel. And the distance to the center of the image 20 is equal to each other, and the image of the blood vessel 20 is positioned at the center in the width direction in both the first short-axis image display region G1 and the second short-axis image display region G2. It is done. That is, by aligning the center depths of the short axis images on the upstream side and the downstream side of the blood vessel 20, a horizontal long axis image is displayed in the long axis image display region G3. By such control, the long axis image corresponding to the reflected signal detected by the long axis ultrasonic array probe 24c is in the vertical direction in the long axis image display region G3 (the vertical axis direction shown in FIG. 4). Is displayed in a straight line at the center, and it is easy to evaluate or observe the state of the long-axis image.

  The blood vessel branch determination unit 112 extracts the plurality of boundary points 126 by the boundary point extraction unit 104, and estimates the center coordinates 130 by the center coordinate estimation unit 106 based on the extracted boundary points 126. This is repeated a plurality of times, and it is determined whether or not the short-axis cross-sectional shape corresponds to the bifurcation of the blood vessel 20 based on the dispersion degree of the estimation result of the center coordinates 130 a plurality of times. For example, after the center coordinate estimation unit 104 estimates the center coordinate 130 N times (for example, 100 times), the dispersion degree of the estimation result of the N center coordinates 130 is equal to or greater than a predetermined threshold value. If it is, it is determined that the short-axis cross-sectional shape corresponds to the branch portion of the blood vessel 20. The degree of dispersion of the estimation results of the plurality of center coordinates 130 corresponds to the degree of variation in the estimation results of the plurality of center coordinates 130 and is preferably a variance, but may be a standard deviation or an average deviation. There may be. FIG. 14 illustrates a case where the degree of dispersion of the estimation result of the plurality of center coordinates 130 (represented by black circles in FIG. 14) is relatively large. The boundary line 124 ′ shown in FIG. 14 corresponds to the short-axis cross-sectional shape corresponding to the branch portion of the blood vessel 20, and the above-described central position identification processing is performed with respect to the short-axis cross-sectional shape corresponding to the branch portion. In this case, the central coordinate 130 estimated by the central coordinate estimation unit 106 is not determined in one place, but is distributed at the central position in each branched blood vessel. Is relatively large.

  15 and 16 are diagrams illustrating a short-axis image and a long-axis image displayed on the monitor screen display device 30 by the display control unit 92 in the ultrasonic measurement of the blood vessel 20 by the measurement device 22. FIG. 15 shows an ultrasonic reflection image corresponding to the blood vessel 20 corresponding to the portion that is not the branching portion, and FIG. 16 shows an ultrasonic reflection image corresponding to the blood vessel 20 corresponding to the branching portion. In FIGS. 15 and 16, the first short-axis images 136 and 136 ′ in the first short-axis image display area G1 and the second short-axis images 138 and 138 ′ in the second short-axis image display area G2 are respectively broken lines. Is shown. As shown in the long-axis display region G3 in FIG. 15, in the ultrasonic reflection image corresponding to the blood vessel 20 corresponding to the portion that is not a branching portion, the long-axis image is rendered relatively clearly in the long-axis display region G3. The On the other hand, as shown in the long-axis display region G3 in FIG. 16, in the ultrasonic reflection image corresponding to the blood vessel 20 corresponding to the branch portion, the long-axis image cannot be clearly drawn in the long-axis display region G3. Evaluation (observation) of the state becomes difficult.

  When the blood vessel branch determining unit 112 determines that the short-axis cross-sectional shape corresponds to the branch portion of the blood vessel 20, the probe movement control unit 114 is separated from the branch portion. The ultrasonic probe 24 is relatively moved. That is, by controlling the three-axis drive motor control circuit 34 via the three-axis drive motor control unit 86, the ultrasonic probe 24 is automatically moved away from the branch portion. Preferably, the blood vessel branch determining unit 112 determines that one of the first short-axis cross-sectional shape and the second short-axis cross-sectional shape corresponds to the branch portion of the blood vessel 20, but the other is a branch. If the ultrasonic probe 24 is not determined to correspond to a part of the blood vessel 20, the ultrasonic probe 24 has not been determined to correspond to the branch part of the blood vessel 20. Relative movement in the direction approaching the short-axis cross-sectional shape.

  When the blood vessel branch determining unit 112 determines that the short-axis cross-sectional shape corresponds to the branch portion of the blood vessel 20, the probe movement notifying unit 116 performs relative movement of the ultrasonic probe 24. A notification that prompts Preferably, a warning or a message prompting the relative movement of the ultrasonic probe 24 to be separated from the branching unit is displayed on the monitor screen display device 30 via the display control unit 92. Preferably, the blood vessel branch determining unit 112 determines that one of the first short-axis cross-sectional shape and the second short-axis cross-sectional shape corresponds to the branch portion of the blood vessel 20, but the other is a branch. If the ultrasonic probe 24 is not determined to correspond to a part of the blood vessel 20, the ultrasonic probe 24 has not been determined to correspond to the branch part of the blood vessel 20. A warning or a message for prompting the relative movement in the direction approaching the short-axis cross-sectional shape is displayed on the monitor screen display device 30. Alternatively, such notification may be performed by voice or alarm sound.

  FIG. 17 is a flowchart for explaining a main part of an example of blood vessel state evaluation control by the electronic control unit 28, and is repeatedly executed at a predetermined cycle.

  First, in step (hereinafter, step is omitted) S1, a short-axis cross-sectional shape of the blood vessel 20 is calculated based on the reflected signal received by the ultrasonic probe 24. Next, in S2, a grid 132 is formed that divides the region including the short-axis cross-sectional shape calculated in S1 into a plurality of regions. Next, in S3, image processing such as image enhancement and image differentiation is performed on the image including the short-axis cross-sectional shape calculated in S1, and a boundary line 124 in the short-axis cross-sectional shape is detected. Next, in S4, three boundary points 126 on the boundary line 124 detected in S3 are extracted at random.

  Next, in S5, an approximate circle 128 including the three boundary points 126 extracted in S4 is created. Next, in S6, the central coordinates of the approximate circle 128 created in S5 are calculated, and the coordinates are estimated as the central coordinates 130 of the short-axis cross-sectional shape calculated in S1 and recorded on the grid 132. Is done. Next, in S7, it is determined whether or not the center coordinates 130, which are the estimation results for N times, have been recorded on the grid 132, that is, whether or not the processes of S4 to S6 have been repeated N times. If the determination in S7 is negative, the processing from S4 onward is executed again. If the determination in S7 is positive, the processing from S8 onward is executed.

  In S8, it is determined whether or not the dispersion degree of the estimation result of the central coordinates 130 for N times related to the processes in S4 to S6 is larger than a predetermined threshold value. If the determination in S8 is affirmative, the processing from S11 onward is executed. If the determination in S8 is negative, in S9, among the squares in the grid 132 formed in S2. The grid in which the largest number of the central coordinates 130 is recorded is selected. Next, in S10, after the average value of the estimation result of the central coordinate 130 included in the grid selected in S9 is identified as the central position 134 in the short-axis cross-sectional shape calculated in S1. This routine is terminated. In S11, it is determined that the short-axis cross-sectional shape calculated in S1 corresponds to the branch portion of the blood vessel 20. Next, in S12, after the movement control for relatively moving the ultrasonic probe 24 so as to be separated from the branch portion or the notification control for prompting such movement is executed, this routine is terminated.

  In the above control, S1 is the operation of the short-axis cross-sectional shape calculation unit 100, S3 and S4 are the operation of the boundary point extraction unit 104, S5 and S6 are the operation of the central coordinate estimation unit 106, and S2 and S6. Is the operation of the estimated central coordinate recording unit 108, S9 and S10 are the operation of the central position identification unit 110, S8 and S11 are the operation of the blood vessel branch determination unit 112, S12 is the probe movement control unit 114 and the This corresponds to the operation of the probe movement notification unit 116, respectively.

  Thus, according to the present embodiment, the short-axis cross-sectional shape calculation unit 100 (S1) that calculates the short-axis cross-sectional shape of the blood vessel 20 based on the reflection signal and the short-axis cross-sectional shape calculation unit 100 calculate the short-axis cross-sectional shape. The boundary point extraction unit 104 (S3 and S4) that randomly extracts a plurality of boundary points 126 on the boundary of the short-axis cross-sectional shape that has been formed, and the plurality of boundary points 126 extracted by the boundary point extraction unit 104 A central coordinate estimation unit 106 (S5 and S6) for estimating the central coordinate 130 in the short-axis cross-sectional shape based on the above, extraction of the plurality of boundary points 126 by the boundary point extraction unit 104, and extraction of the plurality of extracted The estimation of the central coordinate 130 by the central coordinate estimation unit 106 based on the boundary point 126 is repeatedly performed a plurality of times, and based on the average of the estimation results of the central coordinate 130 of the plurality of times. The central position identifying unit 110 (S9 and S10) for identifying the central position 134 in the short-axis cross-sectional shape is provided, so that the central position in the short-axis cross-sectional shape based on the estimation results of a plurality of times. By identifying 134, it is possible to identify the central position 134 more accurately while suppressing the influence of errors. That is, it is possible to provide the measuring apparatus 10 that facilitates measurement.

  The extraction of the plurality of boundary points 126 by the boundary point extraction unit 104 and the estimation of the central coordinates 130 by the central coordinate estimation unit 106 based on the extracted plurality of boundary points 126 are repeatedly performed a plurality of times. A blood vessel branch determination unit 112 (S8 and S11) that determines whether or not the short-axis cross-sectional shape corresponds to a branch portion of the blood vessel 20 based on the scattering degree of the estimation result of the center coordinates 130 a plurality of times. ), The measurement by the measurement device 22 can be made easier by avoiding a branching portion that makes it difficult to measure the blood vessel state.

  The ultrasonic probe 24 that radiates ultrasonic waves to the blood vessel 20 located under the skin of the living body 14 and the blood vessel branch determination unit 112 make the short-axis cross-sectional shape correspond to the branch portion of the blood vessel 20. If it is determined that there is a probe movement control unit 114 (S12) that relatively moves the ultrasonic probe 24 so as to be separated from the branching unit, the measurement of the blood vessel state is performed. Difficult branches can be avoided in a suitable and practical manner.

  The ultrasonic probe 24 that radiates ultrasonic waves to the blood vessel 20 located under the skin of the living body 14 and the blood vessel branch determination unit 112 make the short-axis cross-sectional shape correspond to the branch portion of the blood vessel 20. If it is determined that there is a branch, the probe movement notifying unit 116 (S12) that performs notification for urging the relative movement of the ultrasonic probe 24 is provided, so that it is difficult to measure the blood vessel state. Parts can be avoided in a suitable and practical manner.

  The center coordinate estimation unit 106 creates an approximate circle 128 that includes the plurality of boundary points 126 extracted by the boundary point extraction unit 104, and uses the center coordinates of the approximate circle 128 as the center coordinates in the short-axis cross-sectional shape. Therefore, the central coordinate 130 in the short-axis cross-sectional shape can be estimated in a suitable and practical manner.

  A region including the short-axis cross-sectional shape calculated by the short-axis cross-sectional shape calculation unit 100 is divided into a plurality of regions, and the central coordinate 130 estimated each time the central coordinate estimation unit 106 estimates the central coordinate 130. Including the estimated central coordinate recording unit 108 (S6) that records which of the plurality of sections is included, and the central position identifying unit 110 performs the estimation of the central coordinate 130 a plurality of times by the central coordinate estimating unit 106. After being performed, the average value of the estimation results of the center coordinates 130 included in the section in which the most center coordinates 130 are recorded by the estimated center coordinates recording unit 108 is identified as the center position 134 in the short-axis cross-sectional shape. Therefore, the central position 134 in the short-axis cross-sectional shape can be identified in a suitable and practical manner.

  The preferred embodiments of the present invention have been described in detail with reference to the drawings. However, the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the present invention. Is.

10: sensor holder, 12: probe unit, 14: living body, 16: upper arm, 18: skin, 20: blood vessel, 22: biological blood vessel state measuring device, 24: ultrasonic probe, 24a: ultrasonic wave for first short axis Array probe, 24b: 2nd short axis ultrasonic array probe, 24c: Long axis ultrasonic array probe, 25: Probe surface, 26: Multi-axis drive device, 28: Electronic control device, 30: Monitor screen display device, 32: Ultrasonic drive control circuit, 34: Triaxial drive motor control circuit, 36: Magnet base, 38: Unit fixing tool, 40: Swivel arm, 42: Tip part, 44, 45: Connection Member, 46, 47: link, 48: fitting hole, 50, 51: curved joint, 52: fixed knob, 54: rotating joint, 58: air pump, 60: pressure control valve, 62: cuff, 64: Pressure sensor, 70: Endothelium, 80: Ultrasound Motion control unit, 82: detection processing unit, 84: ultrasonic signal processing unit, 86: triaxial drive motor control unit, 88: cuff pressure control unit, 90: blood vessel state evaluation unit, 92: display control unit, 100: short Axis section shape calculation unit, 102: Long axis section shape calculation unit, 104: Boundary point extraction unit, 106: Center coordinate estimation unit, 108: Estimated center coordinate recording unit, 110: Center position identification unit, 112: Blood vessel branch determination unit 114: Probe movement control unit, 116: Probe movement notification unit, 120: Image, 122: Two-graded image, 124, 124 ′: Boundary line, 126: Boundary point, 128: Approximate circle, 130: Center coordinates, 132: Grid, 134: Center position, 136, 136 ′: First short axis image, 138, 138 ′: Second short axis image, G1: First short axis image display area, G2: Second short axis image display area , G3: Long axis image display area L _1: the intima, L _2: the tunica, L _3: the outer membrane

Claims (6)

A biological blood vessel state measuring device that radiates ultrasonic waves to a blood vessel located in the epidermis of a living body and measures the state of the blood vessel based on a reflected signal of the ultrasonic wave,
A short-axis cross-sectional shape calculating unit for calculating a short-axis cross-sectional shape of the blood vessel based on the reflected signal;
A boundary point extraction unit that randomly extracts at least three boundary points on the boundary of the short axis cross-sectional shape calculated by the short-axis cross-sectional shape calculation unit;
A center coordinate estimation unit that estimates center coordinates in the short-axis cross-sectional shape based on the at least three boundary points extracted by the boundary point extraction unit;
The extraction of the at least three boundary points by the boundary point extraction unit and the estimation of the central coordinates by the central coordinate estimation unit based on the extracted at least three boundary points are repeatedly performed a plurality of times, A biological blood vessel state measuring device comprising: a central position identifying unit that identifies a central position in the short-axis cross-sectional shape based on an average of a plurality of estimation results of the central coordinates. The extraction of the at least three boundary points by the boundary point extraction unit and the estimation of the central coordinates by the central coordinate estimation unit based on the extracted at least three boundary points are repeatedly performed a plurality of times. A blood vessel branch determination unit that determines whether or not the short-axis cross-sectional shape corresponds to the branch portion of the blood vessel based on the degree of dispersion of the estimation result of the center coordinates of times. The biological blood vessel state measuring device according to 1. A probe that emits ultrasonic waves to a blood vessel located in the epidermis of a living body,
When the blood vessel branch determination unit determines that the short-axis cross-sectional shape corresponds to the branch portion of the blood vessel, the probe movement control moves the probe relatively away from the branch portion. The biological blood vessel state measuring device according to claim 2, comprising: a unit. A probe that emits ultrasonic waves to a blood vessel located in the epidermis of a living body,
When it is determined by the blood vessel branch determination unit that the short-axis cross-sectional shape corresponds to the branch portion of the blood vessel, a probe movement notification unit that performs notification that prompts the relative movement of the probe, and The biological blood vessel state measuring device according to claim 2. The center coordinate estimation unit creates an approximate circle that includes the at least three boundary points extracted by the boundary point extraction unit, and estimates the center coordinates of the approximate circle as the center coordinates in the short-axis cross-sectional shape. The biological blood vessel state measuring device according to any one of claims 1 to 4. A region including the short-axis cross-sectional shape calculated by the short-axis cross-sectional shape calculation unit is divided into a plurality of regions, and the center coordinates estimated each time the central coordinate is estimated by the central coordinate estimation unit are the plurality of An estimated center coordinate recording unit that records which of the categories are included,
The central position identifying unit includes the central coordinates included in a section in which the estimated number of central coordinates is recorded by the estimated central coordinate recording unit after the central coordinates are estimated by the central coordinate estimating unit a plurality of times. The biological blood vessel state measuring device according to any one of claims 1 to 5, wherein an average value of the estimation results is identified as a center position in the short-axis cross-sectional shape.