JP4218327B2 - Biological information measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a biological light measuring device that measures the concentration of a metabolite in a living body or changes in the concentration using light, and in particular, can measure the whole brain with a small number of channels and determine an abnormality in the brain state. The present invention relates to a biological information measuring device.
[0002]
[Prior art]
Biological measurement using light having a wavelength in the visible to near-infrared region is extremely useful in clinical medicine because it can easily measure the oxygen metabolism function of the living body without causing harm to the living body. The oxygen metabolism function of a living body corresponds to the oxygenation state (usually called oxygen saturation or oxidation degree) of a specific pigment (hemoglobin, myoglobin, cytochrome aa3) in the living body. Each of these dyes has a light absorption spectrum that changes in the wavelength range from visible to near-infrared depending on the oxygenation state. In addition, light is easy to handle with an optical fiber, and further, it does not harm the living body when used within the range of safety standards.
[0003]
Taking advantage of such optical measurement, a biological optical measurement device that measures an oxygen metabolism function with light of visible to near-infrared wavelength is disclosed in, for example, Japanese Patent Application Laid-Open No. 57-115232 or Japanese Patent Application Laid-Open No. 63-275323. It is described in.
[0004]
In addition, a technology that measures blood volume changes or hemoglobin concentration changes in the cerebral cortex due to brain activity at multiple points and displays the blood volume changes or hemoglobin concentration changes as moving images or still images is a medical physics ( Medical Physics), vol. 22, no. 12, pp 1997-2005 (1995).
[0005]
These devices include a probe including a light irradiation unit and a light receiving unit, a data processing unit, a storage unit, a display unit, and a control unit that controls the entire measurement. Since near-infrared light is also absorbed by the pigment contained in the hair, it is desirable to attach the light irradiation part and the light receiving part so as to avoid the hair. For this reason, the probe is used by being fixed to a carefully selected measurement site.
[0006]
On the other hand, a non-fixed type optical measurement probe has been proposed in Japanese Patent Laid-Open No. 2001-238968. This apparatus is not intended to measure the oxygen metabolism function, but irradiates the skin surface with a laser from a laser diode inside the probe head, and observes an image of the skin surface magnified with a magnifying lens with a CCD camera.
[0007]
Japanese Patent Application Laid-Open No. 7-227388 proposes a biological light measurement device in which a light irradiation unit, a light receiving unit, a data processing unit, a storage unit, a display unit, and a control unit that controls the entire measurement are integrated. .
[0008]
[Problems to be solved by the invention]
The biological light measuring device and the optical measuring probe described above have the following problems.
[0009]
The above-mentioned biological light measurement device is assumed to be used in hospitals and the like, and the device scale is large for use outside hospitals such as general homes, workplaces, and places where people go out. Although the biological optical measuring device described in Japanese Patent Laid-Open No. 7-227388 is intended to achieve miniaturization, the measurement area tends to become wider year by year, so avoid increasing the size of the device with an increase in the number of channels. I can't.
[0010]
Moreover, in the measurement using the above-mentioned biological optical measurement device, a method of measuring a change in blood volume or a change in hemoglobin concentration due to the presence or absence of an external or internal stimulus to the brain is generally used, and in a specific brain activity state There has been no contrivance for judging an abnormality in the brain state from the blood flow distribution image itself.
[0011]
Moreover, the probe for optical measurement proposed in the above-mentioned Japanese Patent Laid-Open No. 2001-238968 is intended for image measurement of the skin surface, and no means for acquiring information relating to the position of the measurement site is provided. For this reason, it has a problem that it is difficult to specify a measurement signal generation site and to compare with an image acquired by a fixed probe.
[0012]
The present invention has been made for the purpose of providing a biological information measuring apparatus that can avoid the increase in size of the apparatus accompanying an increase in the measurement area and can acquire position information of measurement data.
[0013]
The present invention has been made in order to provide a biological information measuring apparatus capable of determining an abnormality in a brain state from a blood flow distribution image itself in a specific brain activity state.
[0014]
[Means for Solving the Problems]
In the present invention, the above-mentioned problems are solved by the following solution means.
[0015]
The relative position of the light irradiating means and the light detecting means with respect to a specific reference position is detected, and the generation site of the measurement signal is specified. This makes it possible to measure the signal while moving the probe without fixing it, and the blood flow distribution can be calculated from the relative position and the measurement signal. Further, by measuring while moving the probe, it is possible to measure a wide area with a small number of channels, so that an increase in the size of the apparatus accompanying an increase in the measurement area can be avoided.
[0016]
Further, the position detecting means detects a relative position of a specific position on the surface of the living body and displays the specific position on a blood flow distribution. This facilitates comparison with measurement data acquired by the fixed probe.
[0017]
Further, by comparing the blood flow distribution with the blood flow distribution in the normal state stored in the data storage means, it is possible to determine an abnormality in the brain state with respect to the normal state.
[0018]
In addition to the above configuration, by providing a stimulus presenting means for applying an external stimulus, it is possible to control the brain activity state at the time of measurement and to increase the accuracy when determining an abnormality in the brain state.
[0019]
Furthermore, by accumulating the blood flow distribution in the normal state for each time zone corresponding to the measurement time, it is possible to reduce the influence of the daily fluctuation of the brain state.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a diagram showing a conventional probe arrangement. The incident points 101 and the detection points 102 are alternately arranged on the shell 103. The shell 103 is attached to the head of the subject 105 by a fixture 104. The incident point 101 and the detection point 102 are fixed so that the mounting position does not shift during measurement.
[0021]
Measurement light emitted from a lamp, a light emitting diode, a semiconductor laser, or the like is incident on the subject 105 from an incident point 101 through an incident optical fiber (not shown). The light that has propagated through the cerebral cortex in the head of the subject 105 passes through a detection optical fiber (not shown) connected to the detection point 102, and a light irradiator (not shown) such as a photodiode or a photomultiplier tube. Sent to and detected.
[0022]
Since the intensity of the detected light varies depending on the blood flow state in the cerebral cortex, the increase or decrease of the blood in the cerebral cortex through which the light has propagated can be measured. The detection signal reflects blood flow information of all the parts through which the light has propagated. For convenience, the midpoint between the incident point 1 and the detection point 2 is a sampling point, and the measured signal value is the blood flow at the sampling point. Information. A plurality of sets of incident / detection points are provided, and blood flow distribution images can be obtained from measurement signals at a plurality of sampling points.
[0023]
FIG. 2 is an example of a probe used in the biological information measuring apparatus according to the present invention. Incident light generated from the light sources 201 and 202 is irradiated to the subject's head through the through-hole 203. A laser diode or the like is used for the light sources 201 and 202. By using incident light having different wavelengths, it is possible to obtain concentration information of oxygenated hemoglobin and deoxygenated hemoglobin contained in blood. The wavelength of the incident light is, for example, 830 nm and 782 nm.
[0024]
The light propagated through the cerebral cortex in the subject's head reaches the photodetector 207 through the through hole 206 and is detected as a light detection signal. The through holes 203 and 206 are filled with a material such as a plastic having a color having a low absorption coefficient for near-infrared light, and are covered with the light shielding plates 204 and 208 so that the light does not leak out of the through holes. The front end portion including the through holes 203 and 206 and the light shielding plates 204 and 208 is fixed to the main body by the detachable portions 205 and 209, and can be disposable.
[0025]
As the position sensors 210 and 211, for example, a Hall element is used, and position information such as an incident point and a detection point is acquired. The position information and the light detection signal detected by the light detector 207 are sent to the outside through the control unit 212 and the external device connection terminal 214. The irradiation and detection are controlled by the control unit 212, and the position information and the light detection signal are associated with each other. Power necessary for driving the device is supplied by a battery 213. In this embodiment, an example of a device in which a light source, a detector, and a control unit are integrated in a probe is described. However, incidence and detection may be performed through an optical fiber from an external control device.
[0026]
FIG. 3 shows a case where position information is acquired according to the present invention. The position sensor 302 is built in the probe 301 and is disposed in the vicinity of the incident point and the detection point from which position information is to be acquired. When there are a plurality of incident points and detection points, position sensors corresponding to the respective incident points and detection points are arranged.
[0027]
In this embodiment, a case where a Hall element is used as the position sensor will be described. In this case, magnets 303 and 304 are attached to a part with little movement such as a subject's neck and waist, and set as a reference position for position measurement. The reference position may be one. The light detection signal detected by the light detector 207 and the position information measured by the position sensor are sent to the controller 305. The blood flow image based on the light detection signal and the position information may be calculated by the controller 305. Alternatively, the light detection signal and the position information may be sent to a remote server via communication means, and the blood flow distribution image may be calculated in the server.
[0028]
FIG. 4 is a diagram for explaining a position information calculation method according to the present invention. Also in this embodiment, a case where position information is acquired using a Hall element will be described. For simplicity, an example of calculating two-dimensional position information will be described.
[0029]
A magnet 401 corresponds to the magnet 303 or 304 in FIG. 3 and indicates a reference position for acquiring position information. The Hall elements 402 and 403 are arranged in the directions orthogonal to each other in the vicinity of the incident point or detection point from which the position information is to be acquired. When the magnetic flux generated from the magnet 401 passes through the Hall elements 402 and 403, a magnetic flux component orthogonal to the Hall element is converted into an electric signal and detected. Therefore, the electrical signal changes due to changes in the distance and inclination between the magnet and the Hall element.
[0030]
Since the positions of the Hall elements 402 and 403 change in accordance with the position of the probe, the distance and inclination between the magnet 401 and the Hall elements 402 and 403 change with the change in position. Using the magnetic flux component 404 detected by the Hall element 402 and the magnetic flux component 405 detected by the Hall element 403, a magnetic flux component 406 that gives position information is calculated by the Pythagorean theorem. When acquiring three-dimensional position information, three Hall elements arranged in directions orthogonal to each other may be used.
[0031]
In this embodiment, a plurality of Hall elements are used in order to acquire position information of one incident point or detection point. For this reason, since the position of each Hall element is not the same, the calculated position information is not accurate. However, the size of the Hall element is about 2 mm on a side, and the spatial resolution of optical measurement is about several centimeters due to the influence of scattering.
[0032]
When comparing the blood flow distribution image measured by the probe described in this embodiment with the blood flow distribution image measured by the fixed probe used in the prior art, the positions are correlated between the two images. Need to be.
[0033]
FIG. 5 is a diagram for explaining an embodiment in which a specific position is displayed on the blood flow distribution image in order to associate the positions. The specific positions 501 to 503 are specified in advance, for example, on both ears or between the eyebrows. A position sensor 505 for detecting a specific position built in the probe 504 is brought into contact with the specific positions 501 to 503 to measure position information of the specific position. When the blood flow distribution image calculated from the light detection signal is displayed, the specific position is displayed on the blood flow distribution image. When a blood flow distribution image is calculated from a light detection signal measured using a fixed probe, it is easy to associate the mounting position of the fixed probe with the specific position.
[0034]
Thus, by acquiring the position information of the specific position and associating the position with the blood flow distribution image, it is possible to compare with the blood flow distribution image acquired by the fixed probe.
[0035]
FIG. 6 is a diagram for explaining an embodiment for calculating an image for determining an abnormality in a brain state. The blood flow distribution image 601 is accumulated in the data storage unit for each time zone of the measurement time. Based on the accumulated blood flow distribution image 601, an average blood flow distribution image 602 calculated for each time zone is stored in the previous term data storage means. Further, a difference image 603 between the blood flow distribution image 601 immediately after the measurement and the average blood flow distribution image 602 is calculated for each time period and stored in the data storage unit.
[0036]
In the above, when the sum of the pixel values of the difference image exceeds a preset threshold value, it is determined that an abnormality has occurred in the brain state. Alternatively, when the addition average image 604 of the difference image immediately after the calculation and the accumulated difference image is calculated, and the sum of the pixel values of the addition average image 604 exceeds a preset threshold, the brain state is abnormal. Is determined to have occurred.
[0037]
In the present embodiment, an example in which an average blood flow distribution image and a difference image are calculated for each measurement time zone has been described, but such classification may not be performed. Moreover, you may categorize according to the event just before a measurement instead of according to measurement time zone. The event is, for example, a meal, defecation, or sleep.
[0038]
In the above embodiments, the case where the Hall element is used as the position sensor for detecting the position information has been described. However, the present invention is not limited to this, and for example, a rotary encoder and a gyro sensor may be combined. In addition, an oxygenated hemoglobin concentration distribution image and a deoxygenated hemoglobin concentration distribution image may be used instead of the blood flow distribution image.
[0039]
In the biological information measuring device, it is desirable to keep the measurement conditions as constant as possible in order to detect an abnormality in the brain state from a change in the blood flow distribution image. In particular, it is important to reproduce the brain activity state at the time of measurement. For this reason, the biological information measuring apparatus according to the present invention includes a stimulus presenting unit that gives external stimuli such as visual stimuli, auditory stimuli, and sensory stimuli to the living body.
[0040]
For example, the stimulus presenting means displays a specific image on a display, and the subject measures the blood flow distribution image while gazing at the image. Alternatively, the stimulus presenting means generates a specific sound from a speaker, and the subject measures the blood flow distribution image while listening to the sound. In this way, when the subject concentrates on the external stimulus, the reproducibility of the brain activity state at the time of measurement can be improved.
[0041]
【The invention's effect】
According to the present invention, it is possible to measure biological information by light over a wide range even if the number of channels is reduced, and it is possible to measure the whole brain at ordinary homes, workplaces, and wherever you go. In addition, it becomes easy to monitor the health condition of the brain.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a conventional probe arrangement.
FIG. 2 is a schematic view of a probe of a biological information measuring apparatus according to an embodiment of the present invention.
FIG. 3 is an explanatory diagram of a means for acquiring position information in an embodiment of the present invention.
FIG. 4 is an explanatory diagram of a method for calculating position information according to an embodiment of the present invention.
FIG. 5 is an explanatory diagram of an embodiment in which a specific position is displayed on the blood flow distribution image and the positions are associated with each other.
FIG. 6 is an explanatory diagram of a method for calculating an image for determining an abnormality in a brain state in an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 101 ... Incident point, 102 ... Detection point, 103 ... Shell, 104 ... Fixture, 105 ... Test subject, 201, 202 ... Light source, 203, 206 ... Through-hole, 204, 208 ... Light-shielding plate, 205, 209 ... Desorption part, 207 ... Photo detector, 210, 211 ... Position sensor, 212 ... Control unit, 213 ... Battery, 214 ... External device connection terminal, 301 ... Comb probe, 302 ... Position sensor, 303,304 ... Magnet, 305 ... Controller, 401: Magnet, 402, 403 ... Hall element, 404, 405 ... Magnetic flux component detected by Hall element, 406 ... Magnetic flux component giving position information, 501 to 503 ... Specific position, 504 ... Probe, 505 ... Position sensor, 601 ... blood flow distribution image for each time zone, 602 ... average blood flow distribution image for each time zone, 603 ... blood flow distribution and average blood flow distribution for each time zone The difference image, 604 ... arithmetic mean of the image of the difference image.

Claims (10)

In the biological information measuring device having at least a probe capable of measuring the activity state of the brain of the subject and a reference position defining means for defining a specific reference position ,
The probe includes a plurality of light irradiating means capable of irradiating light to a partial region of the subject's head, a light detecting means for detecting light passing through the head , and the plurality of lights with respect to the reference position. At least chromatic and respective illumination means, detects a relative position between the light detection means with respect to the reference position, and a plurality of position detecting means arranged close in correspondence to each of said light detecting means and the light irradiating means And
Based on the information on the relative position of each of the plurality of light irradiation means and the relative position of the detection means detected by the position detection means , the corresponding measurement positions are calculated, and the respective measurement positions are calculated. information and the light from the detection means measuring signal is detected, the biological information measuring apparatus characterized by comprising a calculating means for respectively calculating the blood flow distribution. It said position detecting means, the biological information measuring apparatus according to claim 1, wherein the benzalkonium detecting the distance and inclination of each and the light detecting means of the multiple light irradiating means with respect to the reference position. The biological information measuring apparatus according to claim 1, further comprising display means for displaying the measurement position on the blood flow distribution.   The biological information measuring apparatus according to claim 1, further comprising a signal level presenting unit that presents a level of the optical signal detected by the light detecting unit.   The biological information measuring apparatus according to claim 1, further comprising a stimulus presenting unit that applies an external stimulus to the living body.   A data storage means for storing the blood flow distribution; a first computing means for calculating an average blood flow distribution from the blood flow distribution stored in the data storage means; the average blood flow distribution and the blood flow distribution; The biological information measuring device according to claim 1, further comprising: a second calculation unit that performs the comparison calculation.   The data storage means is data storage means for accumulating the blood flow distribution for each time zone corresponding to a measurement time, and the first calculation means is configured to store the average blood flow distribution for each time zone corresponding to the measurement time. The second calculation means is a calculation means for performing a comparison calculation between the average blood flow distribution and the blood flow distribution for each time zone corresponding to a measurement time. The biological information measuring device according to claim 6. The biological information measuring apparatus according to claim 1, wherein a distance between the light irradiation unit and the light detection unit is unchanged. The biological information measuring apparatus according to claim 1, wherein the measurement position is a substantially middle point between the light irradiation unit and the light detection unit. The biological information measuring device according to claim 8 or 9, wherein the light irradiation means and the light detection means are alternately arranged.

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