JP4040224B2 - Blood vessel imaging device and pulse wave signal spatial distribution measuring method and device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for imaging a blood vessel, and more particularly to an apparatus for imaging an artery clearly distinct from a vein.
[0002]
  The present invention also measures the spatial distribution of a pulse wave signal indicating an arterial wave of a living body.DressIs related to the position.
[0003]
[Prior art]
In clinical practice, there is a widespread demand for imaging by distinguishing one of an artery and vein from the other (particularly distinguishing the artery from the vein). For example, arteriosclerosis generally occurs from the peripheral part. If the arterial inner diameter image of the peripheral part can be identified and imaged as a vein image, it can be used as diagnostic information for arteriosclerosis.
[0004]
[Problems to be solved by the invention]
2. Description of the Related Art Conventionally, X-ray angiography apparatuses are widely known as apparatuses that image blood vessels. However, this X-ray angiography has a large burden on the subject, and is usually accompanied by hospitalization, and there is a problem that it is difficult to perform it easily in an outpatient setting.
[0005]
On the other hand, as shown in the ME Society of Japan magazine BME Vol.8, No.5, 1994, pp41-50, a technique for imaging a part of a living body by transillumination has also been proposed. However, with this imaging technique based on fluoroscopy, it is extremely difficult to image an artery clearly distinct from a vein.
[0006]
Conventionally, as a method for extracting only information indicating arterial waves, a living body is irradiated with measurement light of two wavelengths, and a logarithmic value of a pulse wave amplitude is obtained from a detection signal of each measuring light passing through the living body, and the logarithmic values thereof are obtained. A method of obtaining a pulse wave component based on the ratio is known. However, with the method of directly detecting the measurement light in this way, it is impossible to obtain the spatial distribution of the pulse wave signal indicating the pulse wave information.
[0007]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a device that can reduce the burden on a subject and can clearly image an artery from a vein.
[0008]
  In addition, the present invention can measure the spatial distribution of a pulse wave signal indicating an arterial wave of a living body.DressThe purpose is to provide a device.
[0009]
[Means for Solving the Problems]
The first and second blood vessel imaging apparatuses according to the present invention apply optical heterodyne detection to imaging so that high spatial resolution can be secured for a living body that is a scattering medium. The output signal is an image that distinguishes an artery from a vein without a pulse wave by utilizing the fact that the measurement light is modulated by the pulse wave unique to the artery when it irradiates the artery part. is there.
[0010]
Specifically, the first blood vessel imaging device according to the present invention is:
Light source means for emitting measurement light incident on a living body;
Scanning means for scanning the measurement light with respect to the living body;
An optical system that divides a part of the measurement light from the optical path before entering the living body, and then combines it with the measurement light emitted from the living body. An optical heterodyne detection system comprising a frequency shifter for providing a difference, and means for detecting a beat component of the combined measurement light;
It is characterized by comprising image signal generating means for generating an image signal based on the intensity ratio of the pulse wave band signal to the beat signal included in the output signal of this optical heterodyne detection system.
[0011]
In the above configuration, means for analyzing the frequency of the output signal of the optical heterodyne detection system is provided,
It is desirable that the image signal generating means is configured to obtain the intensity ratio from the beat signal and the pulse wave band signal separated from each other on the frequency axis by the frequency analyzing means.
[0012]
Further, the image signal generating means is preferably configured to generate an image signal indicating an arterial portion of the living body when the intensity ratio of the signals is larger than a predetermined threshold.
[0013]
In addition to the light source means, scanning means, and optical heterodyne detection system similar to those described above, the second blood vessel imaging device according to the present invention is capable of generating beat signals included in the output signal of this optical heterodyne detection system. The image signal generating means for generating the image signal based on the degree of modulation at the pulse wave band frequency is provided.
[0014]
In this second blood vessel imaging device,
A pulse wave detection means for detecting a pulse wave of a living body is provided,
The image signal generating means is preferably configured to sample a signal value when the beat signal is in a predetermined phase based on the output signal of the pulse wave detecting means.
[0015]
The image signal generating means is preferably configured to generate an image signal indicating an arterial portion of a living body when the degree of modulation is larger than a predetermined threshold.
[0016]
Furthermore, in any of the above two types of blood vessel imaging devices,
As the light source means, one in which a plurality of light emitting portions emitting the measurement light are arranged one-dimensionally or two-dimensionally is used,
As the optical heterodyne detection system, one capable of detecting in parallel each beat component of the measurement light from the plurality of light emitting units is used,
It is preferable that at least a part of the scanning unit is constituted by the light source unit and the optical heterodyne detection system.
[0017]
Furthermore, the third blood vessel imaging device according to the present invention applies optical heterodyne detection to imaging so that a high spatial resolution can be ensured for a living body as a scattering medium, and measures the optical heterodyne detection system from each other. Two systems with different optical wavelengths are provided, and the oxygen saturation of the measurement light irradiation unit is known from the output signal of the optical heterodyne detection system, and this oxygen saturation is higher in the artery than in the vein. Are imaged separately from veins.
[0018]
Specifically, the third blood vessel imaging device according to the present invention is:
Light source means for emitting first measurement light and second measurement light having different wavelengths from each other;
An incident optical system for causing the first measurement light and the second measurement light to enter the same part of the living body;
Scanning means for scanning the living body with the first measurement light and the second measurement light;
After branching a part of the first measurement light from the optical path before entering the living body, the optical system for synthesizing with the first measurement light emitted from the living body, the branching is performed, and the two optical paths are advanced. A first optical heterodyne detection system comprising: a frequency shifter for giving a frequency difference to the first measurement light; and means for detecting a beat component of the synthesized first measurement light;
After branching a part of the second measurement light from the optical path before entering the living body, the optical system for combining with the second measurement light emitted from the living body, the branching is performed, and the two optical paths are advanced. A second optical heterodyne detection system comprising: a frequency shifter that gives a frequency difference to the second measurement light; and a means for detecting a beat component of the synthesized second measurement light;
A characteristic value uniquely corresponding to the oxygen saturation from the beat component detection signals output from the second optical heterodyne detection system and the first optical heterodyne detection system (of course, the oxygen saturation itself may be used. ) And an image signal generating means for generating an image signal based on the characteristic value.
[0019]
Note that the image signal generation means described above has, for example, the ratio of the logarithmic value of the amplitude amount due to the pulse wave of the beat component detection signal output from each of the first optical heterodyne detection system and the second optical heterodyne detection system. An image signal can be generated as a value.
[0020]
Thus, when generating the image signal based on the ratio of the logarithmic value of the amplitude amount by the pulse wave, for example,
Filter means for extracting a modulation component of the frequency of the pulse wave band from beat component detection signals output from the first optical heterodyne detection system and the second optical heterodyne detection system,
A level measuring unit for measuring the level of the signal extracted by the filter unit;
The image signal generation means may be configured to obtain the amplitude amount due to the pulse wave based on the output signal of the level measurement means.
[0021]
Also, instead of this configuration,
Pulse wave detection means for detecting a pulse wave of a living body;
On the basis of the output signal of the pulse wave detection means, a means for sampling the value of the signal at a timing at which the beat component detection signal takes a peak value and a bottom value,
The image signal generation means may be configured to obtain an amplitude amount by a pulse wave from the sampled signal value.
[0022]
On the other hand, it is desirable that the wavelengths of the first measurement light and the second measurement light are 760 nm and 930 nm, respectively.
[0023]
In the third blood vessel imaging device according to the present invention, when the image signal generating means calculates the characteristic value corresponding to the oxygen saturation of 80 to 90%, the image signal indicating the arterial portion of the living body is generated. It is desirable to be configured to do so.
[0024]
Furthermore, in the third blood vessel imaging device according to the present invention,
As the light source means, one in which a plurality of light emitting sections emitting the measurement light are arranged one-dimensionally or two-dimensionally is used,
As the first and second optical heterodyne detection systems, those capable of detecting beat components of measurement light from the plurality of light emitting units in parallel are used,
It is desirable that these light source means and optical heterodyne detection system constitute at least a part of the scanning means.
[0025]
On the other hand, the first pulse wave signal spatial distribution measuring apparatus according to the present invention is:
Light source means for emitting measurement light incident on a living body;
An optical system that divides a part of the measurement light from the optical path before entering the living body, and then combines it with the measurement light emitted from the living body. An optical heterodyne detection system comprising a frequency shifter for providing a difference, and means for detecting a beat component of the combined measurement light;
It comprises pulse wave signal generating means for forming a pulse wave signal indicating the pulse wave of the living body from the output signal of this optical heterodyne detection system.
[0026]
  As the above pulse wave signal generation meansMore specifically,Generating the pulse wave signal based on the intensity ratio of the pulse wave band signal to the beat signal included in the output signal of the optical heterodyne detection systemIs used. Such a pulse wave signal generation means is preferably configured to generate a pulse wave signal indicating an arterial wave of a living body when the intensity ratio of the signals is larger than a predetermined threshold.
[0027]
  AlsoThe second pulse wave signal spatial distribution measuring device according to the present invention is compared with the first pulse wave signal spatial distribution measuring device.Said pulse wave signal generating meansInstead ofModulation of beat signal included in output signal of optical heterodyne detection system at pulse wave band frequencyDegreeIt is configured to generate a pulse wave signal indicating an arterial wave of a living body when it is larger than a predetermined threshold value.The pulse wave signal generating means is used.
[0028]
  In addition, according to the present invention3The pulse wave signal spatial distribution measuring device of
  Light source means for emitting first measurement light and second measurement light having different wavelengths from each other;
  An incident optical system for causing the first measurement light and the second measurement light to enter the same part of the living body;
  Scanning means for scanning the living body with the first measurement light and the second measurement light;
  After branching a part of the first measurement light from the optical path before entering the living body, the optical system for synthesizing with the first measurement light emitted from the living body, the branching is performed, and the two optical paths are advanced. A first optical heterodyne detection system comprising: a frequency shifter for giving a frequency difference to the first measurement light; and means for detecting a beat component of the synthesized first measurement light;
  After branching a part of the second measurement light from the optical path before entering the living body, the optical system for combining with the second measurement light emitted from the living body, the branching is performed, and the two optical paths are advanced. A second optical heterodyne detection system comprising: a frequency shifter that gives a frequency difference to the second measurement light; and a means for detecting a beat component of the synthesized second measurement light;
  A characteristic value uniquely corresponding to oxygen saturation is calculated from beat component detection signals output from the second optical heterodyne detection system and the first optical heterodyne detection system, respectively, and based on this characteristic value, It comprises a pulse wave signal generating means for forming a pulse wave signal indicating a pulse wave.
[0029]
  This number3In the pulse wave signal spatial distribution measuring apparatus, the image signal generation means includes an amplitude amount of a pulse component of the beat component detection signal output from each of the first optical heterodyne detection system and the second optical heterodyne detection system. Those that generate a pulse wave signal using the ratio of the logarithmic value of the characteristic value as the characteristic value can be suitably used.
[0030]
  Also this first3In the pulse wave signal spatial distribution measuring apparatus, the wavelength λ1 of the first measurement light and the wavelength λ2 of the second measurement light are preferably in the ranges of 600 nm <λ1 <805 nm and 805 nm <λ2 <1100 nm, respectively. Particularly preferably, the wavelength λ1 of the first measurement light is 760 nm, and the wavelength λ2 of the second measurement light is 930 nm.
[0032]
【The invention's effect】
First, the operation of the first and second blood vessel imaging devices according to the present invention will be described.
[0033]
The beat component detection signal (beat signal) output from the optical heterodyne detection system as described above excludes the influence of scattering of the living body, which is a scattering medium, and the light component traveling straight through the living body or a scattered light component close thereto. It shows only the strength.
[0034]
The arterial portion and the vein portion can be identified as follows. When the measurement light irradiates the arterial portion, the output signal of the optical heterodyne detection system is as shown schematically in FIG. 5. It will be superimposed. When the measurement light irradiates the vein portion, basically the pulse wave signal a is not generated.
[0035]
When the output signal changing as shown in FIG. 5 on the time axis is sampled at a certain time and subjected to frequency analysis, a spectrum as shown in FIG. 2 is obtained. In FIG. 2, A is a pulse wave signal component, and B is a beat signal component. The intensity of these pulse wave signals and beat signals fluctuates with the pulsation as shown by the solid and broken lines in the figure.Furthermore, if the measurement light is scattered, absorbed and attenuated in the living tissue, it will fluctuate.
[0036]
However, even if the intensity of the pulse wave signal and the beat signal fluctuates in this way, the intensity ratio thereof is basically unchanged. For example, the intensity ratio of the pulse wave band signal to the beat signal intensity is more than a certain level. If so, it can be considered that a pulse wave signal is generated in that case, that is, the measurement light irradiates the arterial portion. As described above, if the output signal of the optical heterodyne detection system is spatially decomposed along with the scanning of the measurement light to generate an image signal indicating the arterial part or the other part at each scanning point, based on this image signal Thus, the arterial portion can be imaged.
[0037]
As an example, the image signal generating means generates an image signal carrying a relatively high density (low luminance) when the intensity ratio of the pulse wave band signal to the beat signal is larger than a predetermined threshold, and the intensity ratio is If it is configured to generate an image signal carrying a relatively low density (high luminance) when it is equal to or lower than a predetermined threshold value, an artery on the background of the relatively low density is generated based on those image signals. It is possible to obtain an image in which only a portion is shown at a relatively high density.
[0038]
Not limited to this, even if an image signal carrying a higher density is generated as the intensity ratio of the pulse wave band signal to the beat signal is larger, the arterial part is displayed at a higher density that can be clearly distinguished from other parts. Images can be obtained.
[0039]
On the other hand, when the beat signal b is extracted by passing the signal having the waveform shown in FIG. 5 through a band pass filter, the change on the time axis is as shown in FIG. When the measurement light irradiates the arterial portion, the beat signal b is modulated by the pulse wave signal and periodically changes in intensity as illustrated.
[0040]
{IF (H) −IF (L)} / {IF (H) + IF (L) where IF (H) is the signal intensity at the peak and IF (L) is the signal intensity at the bottom in this periodic change. )}, The modulation degree of the beat signal is basically unchanged regardless of fluctuations in the intensity of the pulse wave signal and the beat signal due to the above-described attenuation due to scattering and absorption of the measurement light. . Therefore, if the degree of modulation at the pulse wave band frequency is more than a certain level, it can be considered that the measurement light irradiates the artery portion in that case.
[0041]
As described above, if the output signal of the optical heterodyne detection system is spatially decomposed along with the scanning of the measurement light to generate an image signal indicating the arterial part or the other part at each scanning point, based on this image signal Thus, the arterial portion can be imaged.
[0042]
As an example, the image signal generating means generates an image signal carrying a relatively high density (low luminance) when the modulation degree is larger than a predetermined threshold value, and the modulation degree is equal to or lower than the predetermined threshold value. In some cases, if configured to generate image signals carrying a relatively low density (high brightness), only the arterial portion is relatively high on a relatively low density background based on those image signals. An image indicated by density can be obtained.
[0043]
Not limited to that, even if an image signal carrying a higher density is generated as the degree of modulation increases, an image showing a high density at which the arterial part can be clearly distinguished from other parts can be obtained. .
[0044]
As described above, the pulse wave detection means for detecting the pulse wave of the living body is provided, and the image signal generation means is a signal when the beat signal is in a predetermined phase based on the output signal of the pulse wave detection means. If configured to sample the value, it is always possible to accurately sample the signal intensity IF (H) at the peak and the signal intensity IF (L) at the bottom to obtain the correct degree of modulation. .
[0045]
On the other hand, as the light source means, one in which a plurality of light emitting units emitting measurement light are arranged one-dimensionally or two-dimensionally is used, and each of the measurement light from the plurality of light emitting units is used as an optical heterodyne detection system. If the at least part of the scanning means is constituted by the light source means and the optical heterodyne detection system using a component capable of detecting the beat components in parallel, the mechanical scanning of the measuring light is performed in the one-dimensional direction or 2 The dimensional direction is not required, and the scanning speed, that is, the imaging speed is improved.
[0046]
As described above, when the modulation degree is obtained from the signal value when the beat signal is in the predetermined phase based on the output signal of the pulse wave detection means, the beat signal sampling tends to take time. Thus, it is particularly desirable to omit the mechanical scanning of the measurement light.
[0047]
Next, the operation of the third blood vessel imaging apparatus according to the present invention will be described.
[0048]
In this third blood vessel imaging apparatus, beat component detection signals (beat signals) output from the first and second optical heterodyne detection systems are transmitted through the living body, excluding the influence of scattering of the living body as a scattering medium. Thus, the intensity of only the straight light component or the scattered light component close thereto is shown. These beat signals are modulated at a frequency of about 1 Hz by the pulse wave when the measurement light irradiates the arterial portion.
[0049]
In the first and second optical heterodyne detection systems, when measurement light having different wavelengths is used as described above, the pair of amplitude amounts of modulation components due to pulse waves of beat signals output from both optical heterodyne detection systems. The oxygen saturation can be obtained by calculating a numerical ratio. Since this oxygen saturation is 80 to 90% in arterial blood, if an image signal indicating the arterial part is generated when this degree of oxygen saturation is detected, the arterial part is converted into a vein or other tissue. And can be imaged separately.
[0050]
The intensity of the beat signal is attenuated accordingly if the measurement light is scattered and absorbed by the living tissue, and the degree of attenuation varies depending on the change in the tissue thickness. Even if the intensity of the beat signal fluctuates in this way, the ratio of the above logarithm values compensates for this fluctuation of signal intensity and uniquely corresponds to oxygen saturation, so that the arterial portion can be accurately imaged. it can.
[0051]
As an example, the image signal generating means generates an image signal carrying a relatively high density (low luminance) when the oxygen saturation indicated by the above characteristic value is 80 to 90%, and the oxygen saturation is higher than that. If it is configured to generate an image signal carrying a relatively low density (high brightness) when it is low, only the arterial portion is relatively on the background of the relatively low density based on those image signals. An image shown at a high density can be obtained.
[0052]
On the other hand, as the light source means, one in which a plurality of light emitting units emitting measurement light are arranged one-dimensionally or two-dimensionally is used, and each of the measurement light from the plurality of light emitting units is used as an optical heterodyne detection system. If the at least part of the scanning means is constituted by the light source means and the optical heterodyne detection system using a component capable of detecting the beat components in parallel, the mechanical scanning of the measuring light is performed in the one-dimensional direction or 2 The dimensional direction is not required, and the scanning speed, that is, the imaging speed is improved.
[0053]
As described above, when obtaining the characteristic value from the signal value when the beat signal is in a predetermined phase based on the output signal of the pulse wave detection means, it tends to take time to sample the beat signal. It is particularly desirable to omit mechanical scanning of the measurement light as described above.
[0054]
On the other hand, since the pulse wave signal spatial distribution measuring device according to the present invention obtains a pulse wave signal using an optical heterodyne detection method, basically, a pulse wave signal of only the measurement light irradiation portion can be obtained. it can. Therefore, the spatial distribution of the pulse wave signal related to the living body can be measured by obtaining the pulse wave signal related to two or more parts of the living body using these devices.
[0055]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0056]
<First Embodiment>
FIG. 1 is a schematic configuration diagram showing a blood vessel imaging device according to a first embodiment of the present invention. The apparatus of this embodiment includes a laser 11 that emits measurement light L having a wavelength λ, an optical heterodyne optical system 12, a photodetector 13 that receives the measurement light L emitted from the optical heterodyne optical system 12, and the optical detection. And a frequency analyzer 14 connected to the analyzer 13.
[0057]
The imaging apparatus includes a personal computer 20 that receives the output of the frequency analyzer 14 and constitutes an image signal generating means together with the frequency analyzer 14, and a CRT display device connected to the personal computer 20, for example. And an image monitor 21.
[0058]
Further, an XY stage 23 is provided on which a subject (for example, a human finger) 22 that is a blood vessel imaging target can be placed and moved in a two-dimensional direction. The XY stage 23 is driven by a stage driver 24, and the operation of the stage driver 24 is controlled by the personal computer 20.
[0059]
The optical system 12 that constitutes the optical heterodyne detection system together with the photodetector 13 reflects the measurement light L emitted from the laser 11 into two systems, and the reflected and branched measurement light L. The mirror 31 that is incident on the subject 22, the mirror 32 that reflects the measurement light L that has passed through the half mirror 30, and the measurement light that has passed through the subject 22 with the measurement light L reflected by the mirror 32. It comprises a half mirror 33 that combines with L, and a mirror 35 that reflects the combined measurement light L and guides it to the photodetector 13.
[0060]
In the optical path of the measurement light L that has passed through the half mirror 30, a frequency shifter 34 that is made of, for example, AOM and applies a predetermined frequency shift of the center frequency ω to the measurement light L is inserted.
[0061]
Hereinafter, the operation of the apparatus of the present embodiment having the above configuration will be described. When obtaining a blood vessel image of the subject 22, the subject 22 is irradiated with the measurement light L emitted from the laser 11. At the same time, the measurement light L scans the subject 22 two-dimensionally by driving the XY stage 23.
[0062]
When the measurement light L transmitted through the subject 22 and the measurement light L to which the frequency shift is given by the frequency shifter 34 are combined by the half mirror 33, the combined measurement light L has a beat having the same center frequency ω as the shift frequency. Ingredients are included. The output signal I of the photodetector 13 that has received the combined measurement light L includes a beat signal based on the beat component, and the output signal I is input to the frequency analyzer 14.
[0063]
This beat signal indicates the intensity of only the straight component of the measurement light L that has passed through the subject 22 as a scattering medium and the scattering component close thereto. Therefore, if an image related to the subject 22 is obtained based on the beat signal, high spatial resolution is ensured despite the measurement light L being scattered in the subject 22.
[0064]
The frequency analyzer 14 obtains the spectrum of the output signal I. This spectrum is as shown in FIG. B in the figure is a beat signal component. Further, as described above, when the measurement light L irradiates the artery portion, a pulse wave signal component indicated by A in FIG.
[0065]
The personal computer 20 receives the output of the frequency analyzer 14, obtains the peak value Ib of the beat signal component B of the center frequency ω, and obtains the peak value Ip of the signal in the pulse wave band near the frequency of 1 Hz. The intensity ratio (Ip / Ib) is determined. When the signal intensity ratio (Ip / Ib) is larger than a predetermined threshold, the personal computer 20 generates an image signal Sp carrying a relatively high density (low luminance), and the intensity ratio (Ip / When Ib) is equal to or less than the threshold value, an image signal Sp carrying a relatively low density (high luminance) is generated, and the image signal Sp is input to the image monitor 21.
[0066]
The light detector 13 outputs the signal I for each scanning position of the subject 22 along with the scanning of the measurement light L performed as described above. Accordingly, the binary image signal Sp as described above is also generated for each two-dimensional scanning position of the subject 22.
[0067]
On the image monitor 21, a binary two-dimensional image is reproduced and displayed based on the image signal Sp generated as described above. This image is an arterial image showing only the arterial portion of the subject 22. The reason is as described in detail above.
[0068]
Note that the threshold processing for the signal intensity ratio (Ip / Ib) described above is not performed, and even when an image signal carrying a higher density is generated as the signal intensity ratio (Ip / Ib) is larger, the arterial portion is not. It is possible to obtain an image shown at a high density that can be clearly distinguished from other parts.
[0069]
Second Embodiment
Next, a second embodiment of the present invention will be described. FIG. 3 shows a schematic configuration of a blood vessel imaging apparatus according to the second embodiment of the present invention. In FIG. 3, the same elements as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted unless particularly required.
[0070]
Compared with the apparatus shown in FIG. 1, the apparatus of the second embodiment is provided with a band pass filter 16 and a level measuring instrument 17 instead of the frequency analyzer 14, and in addition thereto, the pulse of the subject 22. A pulse wave signal detector 50 comprising, for example, an electrocardiograph for detecting a wave, and a synchronization detector for sampling the level measurement signal SL output from the level measuring device 17 based on the pulse wave signal Sc from the pulse wave signal detector 50 51 is basically different in that it is provided.
[0071]
The band pass filter 16 receives the output signal I of the photodetector 13, extracts the beat signal Sb in the vicinity of the frequency ω from the output signal I, and inputs the signal Sb to the level measuring device 17. The level measuring device 17 measures the intensity of the beat signal Sb and inputs a level signal SL indicating the signal intensity to the synchronization detecting unit 51. Here, the signal intensity of the beat signal Sb is as shown in FIG. When the measurement light L irradiates the arterial portion, the beat signal Sb is modulated at a frequency of about 1 Hz by the pulse wave as shown in FIG. When the measurement light L irradiates a portion other than the artery, such modulation is not performed.
[0072]
The synchronization detection unit 51 samples the level signal SL based on the pulse wave signal Sc from the pulse wave signal detection unit 50 at a timing such that the peak portion and the bottom portion indicated by black dots in FIG. 4 are detected, A sampling signal is input to the personal computer 20.
[0073]
When the signal intensity at the peak portion is IF (H) and the signal intensity at the bottom portion is IF (L), the personal computer 20 {IF (H) −IF (L)} / {IF (H) + IF ( L)} is obtained. The personal computer 20 generates an image signal Sp carrying a relatively high density (low luminance) when the modulation degree is larger than a predetermined threshold value, and compares the image signal Sp when the modulation degree is equal to or less than the threshold value. An image signal Sp carrying a low density (high luminance) is generated, and the image signal Sp is input to the image monitor 21.
[0074]
The light detector 13 outputs the signal I for each scanning position of the subject 22 along with the scanning of the measurement light L performed as described above. Accordingly, the binary image signal Sp as described above is also generated for each two-dimensional scanning position of the subject 22.
[0075]
On the image monitor 21, a binary two-dimensional image is reproduced and displayed based on the image signal Sp generated as described above. This image is an arterial image showing only the arterial portion of the subject 22. The reason is as described in detail above.
[0076]
It should be noted that the threshold value processing is not performed for the modulation degree {IF (H) −IF (L)} / {IF (H) + IF (L)} described above, and an image signal carrying a higher density as the modulation degree increases. Even if the image is generated, an image showing the arterial portion at a high density that can be clearly distinguished from other portions can be obtained.
[0077]
<Third Embodiment>
FIG. 6 is a schematic configuration diagram showing a blood vessel imaging device according to the third embodiment of the present invention. The apparatus of this embodiment includes a laser 111 that emits a first measurement light L1 having a wavelength λ1 = 760 nm, and a laser 112 that emits a second measurement light L2 having a wavelength λ2 = 930 nm different from the first measurement light L1. The first optical system 113 for the first measurement light L1, the second optical system 114 for the second measurement light L2, and the first photodetector for receiving the measurement light L1 emitted from the first optical system 113 115, a second photodetector 116 that receives the measurement light L2 emitted from the second optical system 114, and a pulse wave of a beat component that is connected to the first photodetector 115 and is included in the measurement light L1 as described later. A first signal detection unit 117 that detects an amplitude amount; a second signal detection unit 118 that is connected to the second photodetector 116 and detects a pulse wave amplitude amount of a beat component included in the measurement light L2 as described later; have.
[0078]
The imaging apparatus also includes a personal computer 120 as an image signal generating unit that receives the outputs of the first signal detection unit 117 and the second signal detection unit 118, and a CRT display device connected to the personal computer 120, for example. And an image monitor 121.
[0079]
In addition, an XY stage 123 is provided on which a subject 122 (for example, a human finger) that is a blood vessel imaging target can be placed and moved in a two-dimensional direction. The XY stage 123 is driven by a stage driver 124, and the operation of the stage driver 124 is controlled by the personal computer 120.
[0080]
Here, FIG. 7 shows absorption spectra of oxidized hemoglobin (OxyHb) and reduced hemoglobin (DeoxyHb), which are light-absorbing substances in blood, together with the absorption spectrum of water (Water) that determines the optical characteristics of the tissue. . As shown here, the absorption spectrum of oxidized hemoglobin and reduced hemoglobin has lower absorption at the shorter wavelength side than the isosbestic point (wavelength 805 nm), while the latter is lower at the longer wavelength side. Absorption characteristics.
[0081]
The wavelength λ1 = 760 nm of the first measurement light L1 is a wavelength that deviates from the isosbestic point wavelength of 805 nm, and the absorption of reduced hemoglobin is particularly large with respect to the absorption of oxidized hemoglobin. On the other hand, the wavelength λ2 = 930 nm of the second measurement light L2 is a wavelength that deviates from the above-mentioned isosbestic point wavelength of 805 nm, and the absorption of oxidized hemoglobin is particularly greater than the absorption of reduced hemoglobin.
[0082]
The first optical system 113 that constitutes the first optical heterodyne detection system together with the first photodetector 115 and the first signal detector 117 includes a half mirror 130 that branches the measurement light L1 emitted from the laser 111 into two systems, The mirror 131 for reflecting the measurement light L1 reflected and branched here to enter the subject 122, the mirror 132 for reflecting the measurement light L1 transmitted through the half mirror 130, and the measurement light L1 reflected by the mirror 132 are reflected. The measuring beam L1 transmitted through the subject 122 and the half mirror 133 to be combined are configured.
[0083]
In the optical path of the measurement light L1 that has passed through the half mirror 130, a frequency shifter 134 that is made of, for example, AOM and applies a predetermined frequency shift of about several tens of MHz to the measurement light L1 is inserted.
[0084]
On the other hand, the second optical system 114 that constitutes the second optical heterodyne detection system together with the second photodetector 116 and the second signal detector 118 is a half mirror 135 that branches the measurement light L2 emitted from the laser 112 into two systems. Then, the mirror 136 that reflects the measurement light L2 that has passed therethrough, and the dichroic mirror 137 that reflects the measurement light L2 that is reflected here and transmits the measurement light L1 so that they both enter the subject 122 through the same optical path. The mirrors 138 and 139 that sequentially reflect the measurement light L2 reflected and branched by the half mirror 135 and the measurement light L2 that has passed through the subject 122 are reflected and the measurement light L1 is transmitted and branched. The dichroic mirror 140 to be reflected, the mirror 141 for reflecting the measurement light L2 reflected there, and the measurement light L2 reflected there are combined with the measurement light L2 reflected by the mirror 139. And a Fumira 142.
[0085]
In the optical path of the measurement light L2 between the mirror 138 and the mirror 139, a frequency shifter 143 configured by, for example, AOM and giving a predetermined frequency shift of about several tens of MHz to the measurement light L2 is inserted. .
[0086]
The half mirror 130 and the mirror 131 of the first optical system 113 and the half mirror 135, the mirror 136 and the dichroic mirror 137 of the second optical system 114 are incident optical devices that allow the measurement lights L1 and L2 to enter the same part of the subject 122. The system is configured.
[0087]
The first signal detector 117 includes a bandpass filter 150 connected to the first photodetector 115, a level measuring device 151 connected to the bandpass filter 150, and a bandpass filter connected to the level measuring device 151. 152 and a level measuring device 153 which is connected to the band pass filter 152 and sends an output to the personal computer 120.
[0088]
On the other hand, the second signal detector 118 includes a bandpass filter 154 connected to the second photodetector 116, a level measuring device 155 connected to the bandpass filter 154, and a bandpass filter connected to the level measuring device 155. 156 and a level measuring device 157 which is connected to the band pass filter 156 and sends an output to the personal computer 120.
[0089]
Hereinafter, the operation of the apparatus of the present embodiment having the above configuration will be described. When obtaining a blood vessel image of the subject 122, the first measurement light L1 emitted from the laser 111 and having the wavelength λ1 = 760 nm and the second measurement light L2 emitted from the laser 112 and having the wavelength λ2 = 930 nm are described above. In this way, the light is synthesized by the dichroic mirror 137 and irradiated on the same point of the subject 122. At the same time, the XY stage 123 is driven, whereby the measurement light L1 and the measurement light L2 scan the subject 122 two-dimensionally.
[0090]
When the measurement light L1 transmitted through the subject 122 and the measurement light L1 to which the frequency shift is given by the frequency shifter 134 are combined by the half mirror 133, the combined measurement light L1 has a beat having the same frequency as the shifted frequency. Ingredients are included. As shown in FIG. 8, the output of the first photodetector 115 that receives the combined measurement light L1 includes the beat signal a1 based on the beat component, but the measurement light L1 irradiates the arterial portion. In this case, the beat signal a1 is modulated at a frequency of about 1 Hz by a pulse wave as indicated by b in the figure.
[0091]
The bandpass filter 150 connected to the first photodetector 115 passes the band signal of the beat signal a1, and the level measuring device 151 measures the level of the beat signal a1 that has passed therethrough. The output of the level measuring device 151 is input to a bandpass filter 152, where the pulse wave modulation component b1 (see FIG. 8) having a frequency of about 1 Hz is extracted. The level measuring device 153 has an amplitude amount ΔI of the pulse wave modulation component b1.₁ And the amplitude amount ΔI₁ Is input to the personal computer 120.
[0092]
Further, when the measurement light L2 transmitted through the subject 122 and the measurement light L2 to which the frequency shift is given by the frequency shifter 143 are synthesized by the half mirror 142, the synthesized measurement light L2 has the same frequency as the shifted frequency. The beat component is included. The output of the second photodetector 116 that receives the combined measurement light L2 is the same as the output of the first photodetector 115 shown in FIG. Hereinafter, with respect to the output of the second photodetector 116, the beat signal a1, the pulse wave modulation component b1 and the amplitude amount ΔI for the output of the first photodetector 115 will be described.₁ Corresponding to the beat signal a2, the pulse wave modulation component b2, and the amplitude amount ΔI.₂ It shall be called.
[0093]
The band-pass filter 154 connected to the second photodetector 116 passes the band signal of the beat signal a2, and the level measuring device 155 measures the level of the beat signal a2 that has passed therethrough. The output of the level measuring device 155 is input to a band pass filter 156, where a pulse wave modulation component b2 having a frequency of about 1 Hz is extracted. The level measuring device 157 has an amplitude amount ΔI of the pulse wave modulation component b2.₂ And the amplitude amount ΔI₂ Is input to the personal computer 120.
[0094]
The beat signal a1 output from the first photodetector 115 indicates the intensity of only the straight component of the measurement light L1 transmitted through the subject 122, which is a scattering medium, and the scattered component close thereto. Therefore, if an image related to the subject 122 is obtained based on the beat signal a1, high spatial resolution is ensured despite the measurement light L1 being scattered in the subject 122. The same applies to the measurement light L2.
[0095]
From the first signal detection unit 117 and the second signal detection unit 118, the pulse wave amplitude amount for each scanning position of the subject 122 in accordance with the scanning of the measurement light L1 and the measurement light L2 performed as described above. ΔI₁ , ΔI₂ Is output.
[0096]
The personal computer 120 uses these pulse wave amplitude amounts ΔI.₁ , ΔI₂ Of each logarithmic value, ie logΔI₁ / LogΔI₂ Ask for. This log ΔI₁ / LogΔI₂ This value corresponds to the oxygen saturation of blood as described above. The personal computer 120 calculates log ΔI obtained for each two-dimensional scanning position of the subject 122.₁ / LogΔI₂ When the value of is a value corresponding to an oxygen saturation of 80 to 90%, an image signal Sp carrying a relatively high density (low luminance) is generated, and values corresponding to other oxygen saturations are set. If it is taken, an image signal Sp carrying a relatively low density (high luminance) is generated.
[0097]
On the image monitor 121, a two-dimensional image is reproduced and displayed based on the image signal Sp generated as described above. This image is an arterial image showing only the arterial portion.
[0098]
Here, the logarithmic value ratio logΔI₁ / LogΔI₂ The reason why is uniquely associated with oxygen saturation will be described. Pulse wave amplitude amount ΔI shown in FIG.₁ This change is caused by a volume change accompanying arterial blood pulsation. The hemoglobin concentration is C, and the absorption coefficient for the hemoglobin wavelength λ1 = 760 nm is E.₁ , And ΔΔ is the change in the optical path length of the arterial blood portion, log ΔI₁ = E₁ C / ΔD. Similarly, pulse wave amplitude amount ΔI₂ , The absorption coefficient for the wavelength λ2 = 930 nm of hemoglobin is E₂ Then logΔI₂ = E₂ ・ C ・ ΔD Therefore logΔI₁ / LogΔI₂= E₁ / E₂ And the absorption coefficient E₁ And E₂ Corresponds to oxygen saturation, so eventually logΔI₁ / LogΔI₂The value of corresponds to oxygen saturation.
[0099]
<Fourth embodiment>
Next, a fourth embodiment of the present invention will be described. FIG. 9 shows a blood vessel imaging device according to a fourth embodiment of the present invention. In FIG. 9, the same elements as those in FIG. 6 are denoted by the same reference numerals, and description thereof will be omitted unless particularly necessary.
[0100]
The apparatus of the fourth embodiment basically differs from the apparatus of FIG. 6 in that a configuration for detecting the levels of the beat signals a1 and a2 in synchronization with the pulse wave of the subject 122 is added. It is. That is, in the present embodiment, a synchronization measuring unit 181 is provided instead of the bandpass filter 152 and the level measuring device 153 in FIG. 6, and a synchronization measuring unit 182 is provided instead of the bandpass filter 156 and the level measuring device 157. A pulse wave signal detector 180 for detecting the pulse wave of the subject 122 is provided.
[0101]
A pulse wave signal detection unit 180 including an electrocardiograph or the like inputs the pulse wave signal Sc to the synchronization detection units 181 and 182. The synchronous measuring unit 181 samples the output signal of the level measuring device 151 in synchronization with the peak portion and the bottom portion of the pulse wave of the subject 122 indicated by the pulse wave signal Sc, and the difference between the sampled two signals, that is, the pulse wave amplitude amount ΔI₁ Ask for. Similarly, the synchronous measuring unit 182 samples the output signal of the level measuring device 153 in synchronization with the peak portion and the bottom portion of the pulse wave of the subject 122 indicated by the pulse wave signal Sc, and the difference between the sampled two signals, that is, the pulse wave Amplitude amount ΔI₂ Ask for.
[0102]
The personal computer 120 uses these pulse wave amplitude amounts ΔI.₁ And ΔI₂ In the same manner as in the third embodiment, the pulse wave amplitude ΔI is received.₁ And ΔI₂ The image signal Sp is generated based on the above.
[0103]
If the apparatus of 1st-4th embodiment demonstrated above is used, it is also possible to measure the spatial distribution of a pulse wave signal. That is, for example, in the apparatus according to the first embodiment, the peak value Ip of the signal in the pulse wave band near the frequency of 1 Hz required by the personal computer 20 and the signal intensity ratio (Ip / Ib) are portions of two or more points of the subject 22. , The spatial distribution of the pulse wave signal due to the arterial wave can be measured.
[0104]
In the apparatus of the second embodiment, the degree of modulation of the beat signal required by the personal computer 20 {IF (H) −IF (L)} / {IF (H) + IF (L)} is two or more points of the subject 22. If it calculates | requires about this part, it will become possible to measure the spatial distribution of the pulse wave signal by an arterial wave.
[0105]
In the apparatus of the third embodiment or the fourth embodiment, the pulse wave amplitude ΔI obtained by the personal computer 120 is used.₁ , ΔI₂ Of each logarithmic value, ie logΔI₁ / LogΔI₂ Is obtained for two or more portions of the subject 122, the spatial distribution of the pulse wave signal due to the arterial wave can be measured.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a blood vessel imaging device according to a first embodiment of the present invention.
FIG. 2 is a graph showing the spectrum of the photodetector output in the imaging apparatus of the first embodiment.
FIG. 3 is a schematic configuration diagram showing a blood vessel imaging device according to a second embodiment of the present invention.
FIG. 4 is a graph showing a beat signal intensity change required in the imaging apparatus of the second embodiment;
FIG. 5 is a schematic diagram for explaining modulation of a beat signal according to the present invention by a pulse wave.
FIG. 6 is a schematic configuration diagram showing a blood vessel imaging device according to a third embodiment of the present invention.
FIG. 7 is a graph showing absorption spectra of oxidized hemoglobin, reduced hemoglobin and water.
8 is a schematic diagram showing a waveform of a beat signal detected by the apparatus of FIG.
FIG. 9 is a schematic configuration diagram showing a blood vessel imaging device according to a fourth embodiment of the present invention.
[Explanation of symbols]
11 Laser
12 Optical heterodyne optical system
13 photodetector
14 Frequency analyzer
16 Bandpass filter
17 level measuring instrument
20 Personal computer
21 Image monitor
22 Subject
23 XY stage
24 stage driver
30, 33, half mirror
31, 32, 35 mirrors
34 Frequency shifter
50 Pulse wave signal detector
51 Sync detector
111, 112 laser
113 First optical system
114 Second optical system
115 First photodetector
116 Second photodetector
117 First signal detector
118 Second signal detector
120 personal computer
121 Monitor
122 Subject
123 XY stage
124 stage driver
130, 133, 135, 142 Half mirror
131, 132, 136, 138, 139, 141 Mirror
134, 143 Frequency shifter
137, 140 Dichroic mirror
150, 152, 154, 156 Bandpass filter
151, 153, 155, 157 level measuring instrument
180 Pulse wave signal detector
181 and 182 Synchronous measurement unit

Claims (21)

Light source means for emitting measurement light incident on a living body;
Scanning means for scanning the measurement light with respect to the living body;
An optical system that divides a part of the measurement light from the optical path before entering the living body, and then combines it with the measurement light emitted from the living body. An optical heterodyne detection system comprising a frequency shifter for providing a difference, and means for detecting a beat component of the combined measurement light;
A blood vessel imaging device comprising image signal generating means for generating an image signal based on an intensity ratio of a pulse wave band signal to a beat signal included in an output signal of the optical heterodyne detection system. Means is provided for frequency analysis of the output signal of the optical heterodyne detection system,
2. The image signal generating means is configured to obtain the intensity ratio from the beat signal and pulse wave band signal separated from each other on the frequency axis by the frequency analyzing means. Blood vessel imaging device.   The image signal generating means is configured to generate an image signal indicating an arterial portion of a living body when the intensity ratio of the signals is larger than a predetermined threshold value. 3. The blood vessel imaging apparatus according to 2. Light source means for emitting measurement light incident on a living body;
Scanning means for scanning the measurement light with respect to the living body;
An optical system that divides a part of the measurement light from the optical path before entering the living body, and then combines it with the measurement light emitted from the living body. An optical heterodyne detection system comprising a frequency shifter for providing a difference, and means for detecting a beat component of the combined measurement light;
A blood vessel imaging apparatus comprising image signal generation means for generating an image signal based on a modulation degree of a beat signal included in an output signal of the optical heterodyne detection system at a pulse wave band frequency. While providing a pulse wave detection means for detecting the pulse wave of the living body,
5. The image signal generating unit is configured to sample a signal value when the beat signal is in a predetermined phase based on an output signal of the pulse wave detecting unit. Blood vessel imaging device.   The said image signal generation means is comprised so that the image signal which shows the arterial part of a biological body may be produced | generated when the said modulation degree is larger than a predetermined threshold value. Blood vessel imaging device. As the light source means, one in which a plurality of light emitting units emitting the measurement light are arranged one-dimensionally or two-dimensionally is used,
As the optical heterodyne detection system, one capable of detecting beat components of measurement light from the plurality of light emitting units in parallel is used, and these light source means and optical heterodyne detection system are at least part of the scanning means. The blood vessel imaging apparatus according to any one of claims 1 to 6, wherein the blood vessel imaging apparatus is configured. Light source means for emitting first measurement light and second measurement light having different wavelengths from each other;
An incident optical system for causing the first measurement light and the second measurement light to enter the same part of the living body;
Scanning means for scanning the living body with the first measurement light and the second measurement light;
After branching a part of the first measurement light from the optical path before entering the living body, the optical system for synthesizing with the first measurement light emitted from the living body, the branching is performed, and the two optical paths are advanced. A first optical heterodyne detection system comprising: a frequency shifter for giving a frequency difference to the first measurement light; and means for detecting a beat component of the synthesized first measurement light;
After branching a part of the second measurement light from the optical path before entering the living body, the optical system for combining with the second measurement light emitted from the living body, the branching is performed, and the two optical paths are advanced. A second optical heterodyne detection system comprising: a frequency shifter that gives a frequency difference to the second measurement light; and a means for detecting a beat component of the synthesized second measurement light;
A characteristic value uniquely corresponding to the oxygen saturation is calculated from the beat component detection signals output by the second optical heterodyne detection system and the first optical heterodyne detection system, respectively, and an image signal is calculated based on the characteristic value. A blood vessel imaging device comprising image signal generating means for generating.   The image signal generation means uses the ratio of the logarithmic value of the amplitude of the pulse wave of the beat component detection signal output from each of the first optical heterodyne detection system and the second optical heterodyne detection system as the characteristic value. 9. The blood vessel imaging device according to claim 8, wherein Filter means for extracting a modulation component of the frequency of the pulse wave band from beat component detection signals output from the first optical heterodyne detection system and the second optical heterodyne detection system;
Level measuring means for measuring the level of the signal extracted by the filter means is provided,
10. The blood vessel imaging apparatus according to claim 9, wherein the image signal generating means is configured to obtain an amplitude amount by the pulse wave based on an output signal of the level measuring means. Pulse wave detection means for detecting the pulse wave of the living body;
Based on the output signal of the pulse wave detection means, means for sampling the value of the signal at the timing when the beat component detection signal takes the peak value and the bottom value is provided,
10. The blood vessel imaging apparatus according to claim 9, wherein the image signal generating means is configured to obtain an amplitude amount by the pulse wave from the sampled signal value.   The blood vessel imaging apparatus according to any one of claims 8 to 11, wherein wavelengths of the first measurement light and the second measurement light are 760 nm and 930 nm, respectively.   The image signal generating means is configured to generate an image signal indicating an arterial portion of a living body when the characteristic value corresponding to an oxygen saturation of 80 to 90% is calculated. The blood vessel imaging apparatus according to any one of 8 to 12. As the light source means, one in which a plurality of light emitting sections emitting the measurement light are arranged one-dimensionally or two-dimensionally is used,
As the first and second optical heterodyne detection systems, those capable of detecting beat components of measurement light from the plurality of light emitting units in parallel are used,
14. The blood vessel imaging apparatus according to claim 8, wherein the light source means and the optical heterodyne detection system constitute at least a part of the scanning means. Light source means for emitting measurement light incident on a living body;
An optical system that divides a part of the measurement light from the optical path before entering the living body, and then combines it with the measurement light emitted from the living body. An optical heterodyne detection system comprising a frequency shifter for providing a difference, and means for detecting a beat component of the combined measurement light;
A pulse wave signal comprising pulse wave signal generating means for forming a pulse wave signal indicating the pulse wave of the living body based on the intensity ratio of the pulse wave band signal to the beat signal included in the output signal of the optical heterodyne detection system. Spatial distribution measuring device. The pulse wave signal generating means, when the intensity ratio of the signal is greater than a predetermined threshold value, according to claim 15, wherein a and generates a pulse wave signal indicating the artery pulse wave of a living body A device for measuring the spatial distribution of pulse wave signals. Light source means for emitting measurement light incident on a living body;
An optical system that divides a part of the measurement light from the optical path before entering the living body, and then combines it with the measurement light emitted from the living body. An optical heterodyne detection system comprising a frequency shifter for providing a difference, and means for detecting a beat component of the combined measurement light;
If the beat signal included in the output signal of the optical heterodyne detection system, the degree of modulation in the pulse wave band frequency is greater than a predetermined threshold value, the pulse wave signal to generate a pulse wave signal indicating the artery pulse wave of a living body An apparatus for measuring a spatial distribution of a pulse wave signal comprising a generating means . Light source means for emitting first measurement light and second measurement light having different wavelengths from each other;
An incident optical system for causing the first measurement light and the second measurement light to enter the same part of the living body;
Scanning means for scanning the living body with the first measurement light and the second measurement light;
After branching a part of the first measurement light from the optical path before entering the living body, the optical system for synthesizing with the first measurement light emitted from the living body, the branching is performed, and the two optical paths are advanced. A first optical heterodyne detection system comprising: a frequency shifter for giving a frequency difference to the first measurement light; and means for detecting a beat component of the synthesized first measurement light;
After branching a part of the second measurement light from the optical path before entering the living body, the optical system for combining with the second measurement light emitted from the living body, the branching is performed, and the two optical paths are advanced. A second optical heterodyne detection system comprising: a frequency shifter that gives a frequency difference to the second measurement light; and a means for detecting a beat component of the synthesized second measurement light;
A characteristic value uniquely corresponding to oxygen saturation is calculated from beat component detection signals output from the second optical heterodyne detection system and the first optical heterodyne detection system, respectively, and based on this characteristic value, A pulse wave signal spatial distribution measuring device comprising pulse wave signal generating means for forming a pulse wave signal indicating a pulse wave. The image signal generation means uses a pulse wave as a characteristic value of a logarithmic value ratio of the amplitude of the pulse component of the beat component detection signal output from each of the first optical heterodyne detection system and the second optical heterodyne detection system. 19. The apparatus for measuring a spatial distribution of a pulse wave signal according to claim 18, wherein the apparatus generates a signal. The first measurement light wavelengths .lambda.1 and second wavelength .lambda.2 is 600nm each measurement light <λ1 <805nm, 805nm <λ2 < pulse wave signal according to claim 18 or 19, wherein in the range of 1100nm Spatial distribution measuring device. 21. The apparatus for measuring a spatial distribution of pulse wave signals according to claim 20, wherein the wavelength λ1 of the first measurement light and the wavelength λ2 of the second measurement light are 760 nm and 930 nm, respectively.

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