JP6732316B2 - Analysis device, analysis program - Google Patents

Description

The present invention relates to a technique for analyzing blood flow of a subject.

As the use of big data and IoT (Internet of Things) expands, various sensing devices are used in various scenes of society, and the flow of measuring various events from various viewpoints and utilizing them in business expands. ing. A similar flow extends to human measurement. In particular, the movement of sensing changes in the brain and living bodies and utilizing them for product development is accelerating.

Hemoglobin in human blood absorbs near infrared light. Therefore, when near-infrared light is irradiated into the human body, the reflection amount of near-infrared light changes according to the change in blood flow. Utilizing this property, the brain is irradiated with near-infrared light from the outside, the reflected near-infrared light is measured, and the amount of received light is analyzed to observe non-invasive changes in brain activity. can do. Furthermore, by measuring multiple locations, it is possible to observe brain activity at multiple locations.

The amount of reflection of the near-infrared light to be sensed includes noise due to body movement and the like. In addition, cerebral blood flow includes changes due to other than brain activity. In order to remove these noises from the measurement result, a device that analyzes brain activity generally has a noise removal function.

The following Patent Document 1 describes "an optical measuring device capable of obtaining light-reception amount information from a measurement site such as cerebral blood flow in which unnecessary light-reception amount information due to a shallow part such as skin blood flow shallower than a measurement site of a subject is removed. Offer. Is provided, the first light-transmitting/receiving unit 11 having a plurality of light-transmitting probes 12 and a plurality of light-receiving probes 13 is provided, and the first light-transmitting/receiving unit 11 has the light-transmitting probes 12 and the light-receiving probes 13 alternately. It is the optical measuring device 1 formed in the grid|lattice arrange|positioned at the 1st setting space|interval, The 2nd light transmission/reception part 15 is the distance between the light transmission probe 16 and the light reception probe 17, and 2nd setting space|interval. Is formed so as to be shorter than the first set interval, and the control unit 20 acquires the first received light amount information of the light from the light sending probe 12 to the light receiving probe 13 and also from the light sending probe 16 to the light receiving probe. It is characterized in that the second received light amount information of the light to 17 is acquired, and the unnecessary received light amount information is removed from the first received light amount information by using the second received light amount information. ] Technology is disclosed (see summary).

JP, 2009-148388, A

For example, when the brain is learning, the part performing the learning is activated and a large amount of blood flows. Therefore, the activity of the brain can be estimated by measuring the blood flow rate. Since brain activity occurs instantaneously, it is important to measure the instantaneous value accurately when measuring the blood flow. If the measurement result of blood flow contains the same instantaneous blood flow change due to pulsation, it is not possible to know the change in blood flow due to any reason, and it is possible to accurately measure the instantaneous value of blood flow due to brain activity. Interfere. Therefore, in the conventional technique as disclosed in Patent Document 1, it is considered that the influence of the pulse is removed by the difference calculation.

On the other hand, it is known that the pulsation occurs when blood is washed away by the heartbeat, the pulsation interval is equivalent to the heartbeat interval, and reflects the human health condition and psychological condition. That is, if both the brain activity and the pulsation interval can be measured from the cerebral blood flow, it is possible to infer more detailed physical and physical activity once. In the related art as disclosed in Patent Document 1, it is not assumed that the pulsation interval is measured at the same time as the brain activity is measured from the cerebral blood flow, so that the influence of the pulse is eliminated. Therefore, it is difficult to measure the pulsation interval using the conventional technique as it is. Even if the difference calculation as in Patent Document 1 is not carried out, it is still difficult to measure the pulsation interval because the component representing the pulse in the measurement result of the cerebral blood flow has a small signal intensity.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a technique capable of accurately measuring a blood flow rate and also accurately measuring a pulsation interval.

The analysis apparatus according to the present invention measures the light reflected at different depths inside the subject, utilizing that the pulsation component is commonly included in the signals with different depths, and the difference in the measurement results Based on this, the blood flow rate due to the brain activity of the subject is obtained, and the change in the blood flow rate due to the pulsation is strengthened based on the addition of the measurement results, and the pulsation interval of the subject is obtained accurately.

According to the analyzer of the present invention, the pulsation interval of the subject can be accurately measured using the measurement result for accurately measuring the blood flow rate of the subject. As a result, the blood flow rate and the pulsation interval can be accurately obtained by the same measurement component.

FIG. 3 is a configuration diagram of an analysis device 100 according to the first embodiment. It is a block diagram of the near-infrared measuring device 110. It is a schematic diagram which shows the relationship between the depth which the near-infrared measuring device 110 measures, and the physical quantity obtained as a result. 6 is a graph illustrating the measurement results obtained by the probes 1 and 2. 7 is a calculation block diagram of an addition program 123 according to the second embodiment. FIG. It is a conceptual diagram explaining the process which calculates|requires a pulsation interval. FIG. 9 is a configuration diagram of an analysis device 100 according to a third embodiment. It is a conceptual diagram explaining the content which the model data 136 has described.

<Embodiment 1>
FIG. 1 is a configuration diagram of an analysis device 100 according to the first embodiment of the present invention. The analysis device 100 is a device that analyzes the blood flow of a subject such as a brain of a living body by irradiating the subject with light. The analysis device 100 includes a near-infrared measurement device 110, each program described below, a storage device that stores data output by each program, and a CPU (Central Processing Unit) 140.

The near-infrared measuring device 110 is a device that irradiates a subject with light and measures the light reflected from the subject. The specific configuration of the near-infrared measuring device 110 will be described later. The near-infrared measuring device 110 can be configured as a part of the analyzing device 100, or can be configured separately from the analyzing device 100 and then the analyzing device 100 captures the measurement result by the near-infrared measuring device 110. You may do it.

The CPU 140 is an arithmetic device that executes each program included in the analysis device 100. For convenience of description, each program may be described below as an operating entity, but it should be added that the CPU 140 actually executes these programs. Each program can be stored in an appropriate storage device included in the analysis device 100. It may be the same as the storage device that stores each data, or may be a different storage device. It may be divided into a plurality of storage devices and stored.

The measurement result acquisition program 121 receives a signal or data representing the measurement result from the near-infrared measurement device 110, performs processing such as shaping as necessary, and then stores the blood flow data 131 in the storage device. Each data described below may be stored in the same storage device as the blood flow data 131 or in another storage device.

The difference calculation program 122 calculates the blood flow volume of the subject by performing a difference calculation to be described later on the blood flow data 131, and stores the result as difference data 132 in the storage device.

The addition program 123 calculates the pulsation interval of the subject by performing an addition operation described later on the blood flow data 131, and stores the result as addition data 133 in the storage device.

The feature amount calculation program 124, for example, with respect to the blood flow amount of the subject described by the difference data 132, (a) the rate of change of the blood flow amount per unit time, (b) the maximum value of the blood flow amount in a predetermined period, Of the feature quantities such as (c) minimum value of blood flow in a predetermined period, (d) difference between maximum and minimum values of blood flow, (e) time interval between extreme values of blood flow, etc. Calculate at least one. The feature amount calculation program 124 stores the calculation result as blood flow amount data 134 in the storage device.

The feature amount calculation program 125, for example, with respect to the pulsation interval of the subject described by the addition data 133, (a) the rate of change of the pulsation interval per unit time, (b) the maximum value of the pulsation interval in a predetermined period, Among the feature quantities such as (c) minimum value of pulsation interval in a predetermined period, (d) difference between maximum value and minimum value of pulsation interval, (e) time interval between extreme values of pulsation interval, etc. Calculate at least one. The feature amount calculation program 125 stores the calculation result as pulsation interval data 135 in the storage device.

FIG. 2 is a configuration diagram of the near-infrared measuring device 110. The near-infrared measuring device 110 includes two or more measuring units 111, a control unit 112, and a communication unit 113. In FIG. 2, for convenience, reference numerals are given to the two measuring units 111-1 and 111-2. Each measurement unit is attached to a different position on the body surface of the subject 200 and performs measurement at that position.

Each measuring unit 111 includes two or more probes. In FIG. 2, a probe 1 that measures blood flow at a depth closer to the body surface than the skull of the subject 200, and a depth closer to the inside of the body than the skull of the subject 200 (the head of the subject 200 is measured. In the case shown, the probe 2 for measuring blood flow is shown. Each probe includes a light emitting unit (light emitting unit) and a light receiving unit (light detector). The light emitted from the light emitting unit to the subject 200 is reflected from the subject 200, and the light receiving unit detects the reflected light.

The control unit 112 controls the operation of each measuring unit 111 and acquires the measurement result by each measuring unit 111. The communication unit 113 outputs data or a signal describing the measurement result of each measuring unit 111 to an external device (analyzing device 100 in FIG. 1).

FIG. 3 is a schematic diagram showing the relationship between the depth measured by the near-infrared measuring device 110 and the resulting physical quantity. Here, it is assumed that the blood flow in the brain of the subject 200 is measured. The measurement results at both the shallow position (depth not reaching the brain) and the deep position (in the brain) are affected by the pulse of the subject 200, and thus both include a component representing the pulse. On the other hand, it is considered that the blood flow fluctuation in the brain is mainly obtained from the probe having a depth reaching the brain, and thus the probe 2 further includes a component representing the blood flow fluctuation in the brain. The noise detected by each probe is different.

Since both the measurement result by the probe 1 and the measurement result by the probe 2 include the component representing the pulse, the component representing the blood flow fluctuation can be left by taking the difference between them. Utilizing this, the difference calculation program 122 subtracts the measurement result of the probe 1 from the measurement result of the probe 2 to calculate the difference data 132 representing the blood flow fluctuation. The process of obtaining the blood flow rate from the blood flow fluctuation may be performed by the difference calculation program 122 and recorded in the difference data 132, or may be performed by the feature amount calculation program 124 and recorded in the blood flow rate data 134. In the first embodiment, the difference calculation program 122 is executed.

By adding the measurement result of the probe 1 and the measurement result of the probe 2, the component representing the pulse can be emphasized. Although the addition result includes a component representing blood flow fluctuation, it is considered that the component representing the pulse has a frequency component corresponding to the pulsation interval of the subject 200 particularly strongly, and thus the signal strength of the component representing the pulse is included. If it can be sufficiently secured, it is relatively easy to extract it. Utilizing this, the addition program 123 adds the measurement results of the probes 1 and 2 to calculate the addition data 133 representing the pulse. The process of obtaining the pulsation interval from the component representing the pulse may be executed by the addition program 123 and recorded in the addition data 133, or may be executed by the feature amount calculation program 125 and recorded in the pulsation interval data 135. In the first embodiment, the addition program 123 is executed.

FIG. 4 is a graph illustrating the measurement results of the probes 1 and 2. Both the probes 1 and 2 include a component representing a pulse, but the signal intensity of that component is smaller than the signal intensity of the entire measurement result. By adding the measurement results of the probes 1 and 2, the component representing the pulse can be emphasized as shown in the lower right of FIG. 4, and by obtaining the difference between them, as shown in the upper right of FIG. It is possible to make the component representing the blood flow fluctuation clear.

<Embodiment 1: Summary>
The analysis apparatus 100 according to the first embodiment utilizes the fact that the pulsation component is common for different depths, and by obtaining the difference between the measurement results, the blood flow volume is obtained by removing the pulsation component, and by adding The pulsation component is strengthened to obtain the pulsation interval. As a result, the pulsation interval can be accurately obtained by using the device configuration that is supposed to measure the blood flow rate.

<Second Embodiment>
In the second embodiment of the present invention, a method of improving the measurement result by the near-infrared measuring device 110 before obtaining the blood flow rate and the pulsation interval will be described. Since the analysis apparatus 100 has the same configuration as that of the first embodiment except the configuration related to the improvement, the differences will be mainly described below.

FIG. 5 is a calculation block diagram of the addition program 123 according to the second embodiment. Depending on the position of the probe on the subject 200, a clear measurement result may not always be obtained. Therefore, the addition program 123 calculates the S/N ratio of the measurement result acquired from each measurement unit 111, and adds only the measurement result having a good S/N ratio. A plurality of techniques for signal-to-noise ratio determination are known in signal processing, and as one example, each frequency component of a signal is calculated by Fourier transform or the like to determine the frequency of pulsation (about 0.5 to 3 Hz). The ratio of the intensity peaks of the components and the intensity of the other frequency components can be used as the S/N ratio, and from the variation of the S/N ratios of the measured signals, the standard deviation of 2 can be obtained assuming a normal distribution. A signal within the double range is adopted as good.

The addition program 123 calculates the spectrum of the frequency component representing the pulse (the spectrum of the frequency range corresponding to the pulse) among the measurement results acquired from each measurement unit 111. The addition program 123 selects only the measurement result of which the calculated spectrum is equal to or more than the predetermined threshold, and discards the other measurement results. The subsequent steps are the same as in the first embodiment. In the example shown in FIG. 5, since the S/N ratios of the measurement points 1 and 4 are good, the addition program 123 leaves only these measurement results and discards the others. The component representing the pulse is determined by the biological species of the subject 200, but if it is a human, it will be about 20 Hz to 200 Hz.

When the subject 200 is a brain of a living thing, the brain functions differently depending on the site, and therefore, in order to measure the activity of each different site, the measurement units 111 are arranged at a plurality of positions on the head to measure the activity of each site. There is a case. The method described with reference to FIG. 5 can improve the S/N ratio by utilizing the fact that a plurality of measurement results can be obtained when obtaining the measurement results at such a plurality of locations.

FIG. 6 is a conceptual diagram illustrating a process of obtaining the pulsation interval. In general, when obtaining the blood flow in the brain, it is important to obtain the instantaneous value accurately, and it may not be required that the measurement frequency is high. On the other hand, since the pulsation interval constantly changes, it is necessary to increase the measurement frequency in order to measure the pulsation interval accurately. In the present invention, since the configuration for measuring the blood flow is used, the pulsation interval is obtained using the data having the low sampling frequency. Then, as shown in the upper right of FIG. 6, the pulsation interval (RR interval in FIG. 6) may be erroneously obtained.

Therefore, the addition program 123 interpolates the sampling interval for the addition data 133. For example, the measurement result can be interpolated by obtaining an approximate curve using a known method such as curve fitting. As a result, the correct pulsation interval can be obtained as shown in the lower right part of FIG.

In FIG. 6, the interval between the maximum values of the signal intensity may be treated as a pulsation interval, or the interval between the minimum values may be treated as a pulsation interval. However, it is preferable to use the minimum value of the signal intensity when the measurement is performed by utilizing the fact that the received light intensity decreases when blood flow is large because blood absorbs light. When the heart contracts, the movement of the heart is steeper than when it is relaxed, so the signal waveform near the minimum value of the signal intensity is also steep (the systolic blood flow increases, so more light is absorbed and the signal intensity increases. This is because it is easy to identify the minimum value.

When the subject 200 is a living brain, the sampling frequency of the measurement unit 111 required for measuring the cerebral blood flow is approximately 32 Hz or less. The method described with reference to FIG. 6 can accurately measure the pulsation interval even when such a sampling frequency is small.

<Third Embodiment>
In the third embodiment of the present invention, a method of analyzing the physiological state of the subject 200 using the blood flow rate data 134 and the pulsation interval data 135 will be described. Since other configurations are similar to those of the first and second embodiments, the differences will be mainly described below.

FIG. 7 is a configuration diagram of the analysis device 100 according to the third embodiment. In the third embodiment, the analysis device 100 includes model data 136 and an output program 126 in addition to the configurations described in the first and second embodiments.

FIG. 8 is a conceptual diagram for explaining the contents described in the model data 136. An emotion model that expresses human emotions two-dimensionally by a relative relationship between pleasant/unpleasant axes and active/inactive axes is known as Russel's two-dimensional emotion model. The model data 136 is data that describes the correspondence relationship between the emotion model and the measurement result by the analysis device 100.

Specifically, the model data 136 associates the heartbeat interval and the equivalent pulsation interval with pleasantness/discomfort based on known cases, and correlates the frontal lobe blood flow with active/inactive, It is assumed that the shorter the interval or pulsation interval, the greater the comfort, and the more frontal blood flow, the more active the brain. The model data 136 describes the correspondence relationship between the two-dimensional space represented by the heartbeat interval or the pulsation interval and the frontal lobe blood flow and each emotion in the Russell two-dimensional emotion model in an appropriate data format. The feature amount calculation program 124 or 125 inquires the model data 136 using the blood flow rate and the pulsation interval described by the blood flow rate data 134 and the pulsation interval data 135, respectively, and thereby, from the relative relationship of the two axes, The position in the two-dimensional emotion model of FIG. 8 is known, and the emotion of the subject 200 can be estimated.

It is known that the pulsation interval is constantly changing with time, and that the change is caused by the activity of the parasympathetic nerve and that of both the sympathetic and parasympathetic nerves. Specifically, in the frequency spectrum of the temporal waveform of the pulsation interval, components above a certain frequency are mainly derived from the activity of the parasympathetic nerve, and components below that frequency are derived from the activity of both the sympathetic and parasympathetic nerves. Can be assumed to be. The feature amount calculation program 125 can estimate the physiological state of the subject 200 by utilizing this.

For example, the feature amount calculation program 125 includes, in the frequency spectrum of the pulsation interval, the total HF of power spectra above the threshold frequency (the area of the power spectrum waveform above the threshold frequency) and the total LF of power spectra below the threshold frequency (the threshold frequency. The ratio (LF/HF) of the power spectrum waveform area of less than is obtained. It can be said that the parasympathetic nerve is dominant when the LF/HF is small, and the sympathetic nerve is dominant when the LF/HF is large. Thereby, for example, the stress state of the subject 200 can be estimated.

As an example, there is an examination in which the state in which the subject 200 is sitting on a chair and the operation of standing up from the chair are alternately repeated to measure the frequency spectrum of the pulsation interval. Generally, when the person is sitting, the parasympathetic nerve is dominant, so that HF is increased, and when the person is standing, the sympathetic nerve is dominant, so that LF is increased. It is presumed that the subject 200 whose HF does not increase much (sitting LF/HF does not decrease) even when sitting is stressful.

The output program 126 outputs the calculation result of each program in an appropriate format. For example, (a) a feature amount calculation program 124 for outputting the blood flow rate described by the blood flow rate data 134 and the pulsation interval described by the pulsation interval data 135 in a graph format along the time axis. The feature amount calculated by 125 is written together with the graph, (c) the emotion estimation result based on the model data 136 or a two-dimensional graph is output, (d) the value of LF/HF and the physiological value of the subject 200 based on this value. It is possible to output the estimation result of the state.

The output format of the output program 126 is, for example, an image or a character in an appropriate format for screen output, and data shaped into an appropriate data format for output as data.

<Regarding Modifications of the Present Invention>
The present invention is not limited to the above-mentioned embodiments, but includes various modifications. For example, the above-described embodiments have been described in detail for the purpose of explaining the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of a certain embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of a certain embodiment. Further, with respect to a part of the configuration of each embodiment, other configurations can be added/deleted/replaced.

In the above embodiment, two or more of the programs may be integrated. For example, the difference calculation program 122 and the feature amount calculation program 124 may be configured as one program (first analysis unit), and the addition program 123 and the feature amount calculation program 125 may be configured as one program (second analysis unit). .. Further, these may be configured as modules and configured to be called by another program (analyzing unit).

In the above embodiments, instead of each program, hardware such as a circuit device that implements these functions can be used to realize equivalent functions, or the software can be implemented as described in the embodiments. You can also

In the above embodiments, the brain activity of the living thing is measured as the subject 200, but similarly for other living body subjects, the blood flow rate and the pulsation interval are determined using the measurement results of different depths. Can be measured. For example, when measuring the blood flow in a muscle and measuring the pulsation interval, the depth near the center of the muscle and the depth near the epidermis may be measured. When the subject 200 is a human brain, the probe 1 measures a depth of about 1 cm from the body surface, and the probe 2 measures a depth of about 3 cm from the body surface.

100: Analysis device 110: Near infrared measuring device 111: Measuring unit 121: Measurement result acquisition program 122: Difference calculation program 123: Addition program 124: Feature amount calculation program 125: Feature amount calculation program 126: Output program 131: Blood flow Data 132: Difference data 133: Addition data 134: Blood flow rate data 135: Pulsation interval data 136: Model data 140: CPU
200: subject

Claims (10)

An analyzer for analyzing blood flow of a subject, comprising:
A light irradiation unit that irradiates the subject with light,
A photodetector for detecting the light reflected from the subject,
An analysis unit that analyzes the signal intensity acquired by the photodetector detecting the light,
Equipped with
The analysis unit is
The photodetector detects a first signal intensity obtained by the photodetector detecting the light reflected at the first depth of the subject, and the light reflected at the second depth of the subject. A first analysis unit that calculates a difference between the acquired second signal intensity and the calculated blood flow volume using the difference.
A second analysis unit for adding the first signal strength and the second signal strength and calculating the pulsation interval of the blood flow using the signal strength obtained by the addition;
An analysis device having: The second analysis unit,
By interpolating the signal intensity obtained by the addition along the time axis, a plurality of maximum values or minimum values of the signal intensity detected by the photodetector are obtained, and the interval between the obtained maximum values or minimum values is set. The analysis apparatus according to claim 1, wherein the pulsation interval is calculated using the pulsation interval. The analysis device comprises a plurality of the photodetectors,
The second analysis unit is a ratio of signal intensity obtained by detecting the light by each photodetector, to a frequency range corresponding to the pulsation of the blood flow and a frequency range other than that. Is calculated as the S/N ratio,
The said 2nd analysis part uses only the said 1st and 2nd signal strength in which the said calculated S/N ratio is within the range of the preset threshold value as the object of the said addition. Analyzer. The analysis unit calculates a frequency spectrum of the pulsation interval,
The analysis unit outputs, as the result of the analysis, a ratio of a power spectrum in a region above a predetermined frequency to a power spectrum in a region below the predetermined frequency in the frequency spectrum. Analyzer. The light irradiation section irradiates the light to the head of an organism as the subject,
The analysis device further includes a storage unit that stores emotion model data describing a correspondence relationship between the blood flow rate of the organism, the pulsation interval of the organism, and the emotions of the organism,
The analysis unit estimates the emotion possessed by the living thing by referring to the emotion model data by using the calculated blood flow rate and the calculated pulsation interval. Item 1. The analysis device according to item 1. The first analysis unit is configured to calculate a change rate of the blood flow rate per unit time, a maximum value of the blood flow rate in a predetermined period, a minimum value of the blood flow rate in a predetermined period, and a difference between the maximum value and the minimum value. The analysis apparatus according to claim 1, wherein at least one of a time interval between extreme values of the blood flow is calculated. The second analysis unit is a change rate of the pulsation interval per unit time, a maximum value of the pulsation interval in a predetermined period, a minimum value of the pulsation interval in a predetermined period, a difference between the maximum value and the minimum value. The analysis device according to claim 1, wherein at least one of a time interval between extreme values of the pulsation interval is calculated. The analysis device according to claim 1, further comprising an output unit that outputs a processing result of the analysis unit to the outside of the analysis device. The subject is the brain of a living being,
The light irradiating unit irradiates light with a focus at a depth closer to the body surface than the skull of the creature, and a first irradiating unit with light at a depth closer to the body than the skull of the organism. Has two irradiation parts,
The first analysis unit calculates the blood flow in the brain by the difference,
The analysis apparatus according to claim 1, wherein the second analysis unit calculates the pulsation interval of the living thing by the addition. An analysis program for causing a computer to execute a process of analyzing blood flow of a subject, wherein the computer
A step of obtaining the signal intensity obtained by detecting the light reflected from the subject by irradiating the subject with light,
An analysis step of analyzing the signal strength,
Run
In the analysis step, the computer,
The photodetector detects a first signal intensity obtained by the photodetector detecting the light reflected at the first depth of the subject, and the light reflected at the second depth of the subject. A difference between the second signal intensity acquired by calculating the difference, and calculating the blood flow rate of the blood flow using the difference, a first analysis step,
A second analysis step of adding the first signal strength and the second signal strength and calculating the pulsation interval of the blood flow using the signal strength obtained by the addition;
An analysis program which is characterized by executing.

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