JP2006239444A5 - - Google Patents

Description

Blood vessel imaging device, blood vessel identification device, and scattering fluid flow velocity measurement device

The present invention relates to an apparatus for imaging a blood vessel, and more particularly to an apparatus for distinguishing and imaging one of an artery and a vein from the other.
The present invention also relates to a device that can clearly distinguish an artery and a vein.

  Furthermore, the present invention relates to an apparatus for measuring the flow velocity of scattering fluid (fluid that scatters light) such as arterial blood and venous blood.

  In the clinic, there is a wide demand for distinguishing one of an artery and a vein from another and imaging it. 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.

  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.

On the other hand, as shown in Non-Patent Document 1, a technique for imaging a part of a living body by optical transparency has also been proposed.
Journal of the ME Society of Japan BME Vol.8, No.5,1994, pp41-50

  However, with this imaging technique based on transillumination, it is extremely difficult to clearly image one of an artery and a vein from the other.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an apparatus capable of clearly identifying one of an artery and a vein from the other and imaging it with less burden on a subject. To do.

  It is another object of the present invention to provide an apparatus that can clearly discriminate between an artery and a vein with less load on the subject.

  A further object of the present invention is to provide a scattering fluid flow rate measuring device capable of accurately measuring the flow rate of scattering fluid (fluid that scatters light) such as arterial blood and venous blood.

A blood vessel imaging device according to the present invention comprises:
A light irradiation means for irradiating a living body with measurement light;
It comprises imaging means for imaging arteries and / or veins of the living body based on the spectrum spread of the irradiated measurement light due to the interaction with the living body.

In the blood vessel imaging device according to the present invention , the imaging means detects the frequency component of the measurement light scattered by the living body, detects the half-value width of the spectrum of the frequency component detection signal, What images an artery and / or vein based on a value range is preferably used.

  Further, as this imaging means, the frequency component of the measurement light scattered in the living body is detected, the intensity of the center-shift frequency component deviating from the center frequency of the frequency component detection signal is detected, and the artery and the based on this intensity are detected. It is also possible to use one that images a vein.

  Also, as this imaging means, the frequency component of the measurement light scattered by the living body is detected, and the ratio between the intensity of the center frequency component of the frequency component detection signal and the intensity of the frequency component that deviates from the center frequency by a predetermined width is detected. However, it is possible to use an image of the artery and / or vein based on this ratio.

  Further, as this imaging means, one that detects the frequency component of the measurement light scattered by the living body based on the optical heterodyne detection signal can be suitably used.

On the other hand, the blood vessel identification device according to the present invention includes:
A light irradiation means for irradiating a living body with measurement light;
It comprises identification means for discriminating between arteries and veins of the living body based on the spectrum spread of the irradiated measurement light due to the interaction with the living body.

  In this blood vessel identification device, the identification means detects the frequency component of the measurement light scattered by the living body, detects the half-value width of the spectrum of the frequency component detection signal, and based on this half-value width, the artery What distinguishes a vein from a vein is preferably used.

  Further, as the identification means, the frequency component of the measurement light scattered in the living body is detected, the intensity of the center deviation frequency component deviating from the center frequency of the frequency component detection signal is detected, and the artery and the arteries are detected based on this intensity. What distinguishes from a vein can also be used.

  In addition, as the identification means, the frequency component of the measurement light scattered by the living body is detected, and the ratio between the intensity of the center frequency component of the frequency component detection signal and the intensity of the frequency component deviating from the center frequency by a predetermined width is detected. It is also possible to use one that distinguishes the artery and vein based on this ratio.

  Furthermore, as this identification means, what detects the frequency component of the measurement light scattered by the living body based on the optical heterodyne detection signal can be suitably used.

On the other hand, the scattering fluid flow velocity measuring device according to the present invention is:
A light irradiation means for irradiating the scattering fluid with measurement light;
It comprises analysis means for analyzing the flow velocity of the scattering fluid on the basis of the spectrum broadening due to the interaction of the irradiated measurement light with the scattering fluid.

  In this scattering fluid flow velocity measuring device, the analysis means detects the frequency component of the measurement light scattered by the fluid, detects the half-value width of the spectrum of the frequency component detection signal, and based on this half-value width What analyzes the said flow rate is used suitably.

  Also, as this analysis means, the frequency component of the measurement light scattered by the fluid is detected, the intensity of the center deviation frequency component deviating from the center frequency of the frequency component detection signal is detected, and the flow velocity is calculated based on this intensity. What is analyzed can also be used.

  Also, as this analysis means, the frequency component of the measurement light scattered by the fluid is detected, and the ratio between the intensity of the center frequency component of the frequency component detection signal and the intensity of the frequency component deviating from the center frequency by a predetermined width is detected. In addition, a device that analyzes the flow rate based on this ratio can also be used.

  Further, as this analyzing means, a means for detecting the frequency component of the measurement light scattered by the fluid based on the optical heterodyne detection signal can be suitably used.

First, the effect of the blood vessel imaging apparatus of the present invention will be described by taking one form of the apparatus as an example . 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.

  When the fluid that multi-scatters the measurement light flows perpendicularly to the traveling direction of the measurement light, the peak value of the beat signal is lowered and the spectrum is expanded. FIG. 4 schematically shows how the Doppler spreads. (1), (2), (3), and (4) show the cases where the flow velocity is higher in this order, starting with the case of zero flow velocity in (1). The peak value of the beat signal I decreases as the time increases, and the Doppler spread of the spectrum increases.

  Blood is also a fluid that scatters light multiple times. Therefore, this phenomenon occurs when measurement light passes through a blood vessel. And since the flow velocity of the arterial blood flow is generally larger than the flow velocity of the venous blood flow, when the measurement light is transmitted through the arterial portion and the case where the measurement light is transmitted through the venous portion, the peak value decreases and The spread of the spectrum is more remarkable in the former.

  FIG. 5 shows the above points in an easy-to-understand manner. A curve a in the figure shows the spectrum spread of the beat signal I due to the arterial blood flow, and a curve b shows the spectrum spread of the beat signal I due to the venous blood flow. Therefore, for example, a bandpass filter (BPF) having a pass characteristic indicated by a curve c in the figure is used to detect a band component in the vicinity of a frequency (ω + Δf) that deviates from the center frequency ω of the beat signal I by a predetermined width Δf. If an image signal is generated based on the magnitude relationship between the detected center-shift beat signal and a predetermined threshold value, only the arterial portion or only the vein portion can be imaged.

  That is, for example, if a threshold value as indicated by d in FIG. 5 is set and an image signal is generated only from a center shift beat signal larger than that, an image signal indicating only the arterial portion can be obtained. On the other hand, if an image signal is generated only from a center shift beat signal smaller than the threshold value, an image signal indicating only the vein portion can be obtained.

  In more detail, the spectrum spread of the beat signal I due to arterial blood flow is not constant. That is, as shown in FIG. 6, the spectrum spread of the beat signal I due to the highest blood flow of the artery is as shown by the curve a-1, whereas the spectrum spread of the beat signal I due to the lowest blood flow of the artery is that of the curve a-2. It will be like that. If the spectrum spread of the beat signal I due to the minimum arterial blood flow indicated by the curve a-2 is limited to the band pass filter (BPF) indicated by the curve c, the beat signal due to the venous blood flow indicated by the curve b is shown. Since it is approximated to the spectrum spread of I, it may be difficult to distinguish both of them.

  Therefore, as described above, the time point when the spectrum spread due to the pulsation of the beat component detection signal has a substantially constant phase (most preferably the time point when the highest blood flow of the artery occurs) is detected by the in-phase point detection means, and the synchronization detection means By sampling the center shift beat signal at the time of detection and inputting the center shift beat signal to the image signal generation means, the arterial portion and the vein portion can be clearly identified and imaged.

  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. When performing synchronization detection as described above, sampling of the center-shift beat signal tends to take time, so it is particularly desirable to omit the mechanical scanning of the measurement light as described above.

Next, the effect of the blood vessel imaging apparatus of the present invention will be described taking another form of the apparatus as an example . 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.

When the fluid that multi-scatters the measurement light flows perpendicularly to the traveling direction of the measurement light, the peak value of the beat signal is lowered and the spectrum is expanded. FIG. 11 schematically shows how the Doppler spreads. (1), (2), (3), and (4) show the cases where the flow velocity is higher in this order, starting with the case of zero flow velocity in (1). The peak value of the beat signal I decreases as the time increases, and the Doppler spread of the spectrum increases. The above is the same as in the blood vessel imaging apparatus of the form described above .

  Therefore, considering the ratio between the signal intensity I (ω) of the component of the center frequency ω of the beat signal and the signal intensity I (ω + Δf) of the component of the center shift frequency (ω + Δf) deviating from the predetermined width Δf therefrom, this intensity is considered. The ratio I (ω + Δf) / I (ω) changes approximately as shown in FIG. 12 according to the fluid flow velocity v.

  Blood is also a fluid that scatters light multiple times. Therefore, this phenomenon also occurs when measurement light passes through a blood vessel. And since the flow velocity of arterial blood flow is generally larger than the flow velocity of venous blood flow, when the measurement light is transmitted through the arterial part and the case where the measurement light is transmitted through the venous part, the former case is more The intensity ratio I (ω + Δf) / I (ω) becomes larger.

  The value of the beat signal itself varies under the influence of attenuation due to absorption and scattering when the measurement light passes through the living body. However, the intensity ratio I described above, that is, the intensity I (ω + Δf) is used as the intensity I of the center frequency component. The value normalized by (ω) compensates for the influence of measurement light attenuation and basically changes as described above according to only the blood flow velocity.

  Therefore, based on the value of the signal intensity ratio I (ω + Δf) / I (ω) obtained at the scanning light scanning position in the image signal generation means, for example, an image that takes a larger value as the value becomes larger. If the signal is generated, the arterial portion and the vein portion can be clearly identified from each other by density and luminance and imaged.

Next, the effect of the blood vessel imaging apparatus of the present invention will be described by taking still another embodiment of the apparatus as an example . Since the signal intensity ratio I (ω + Δf) / I (ω) described above corresponds to the spectrum waveform of the beat signal, an image signal is generated based on the spectrum waveform of the beat signal instead of the signal intensity ratio. Also, the arterial portion and the vein portion can be distinguished from each other and imaged. The blood vessel imaging apparatus of this embodiment performs imaging in this way.

That is, the blood vessel imaging apparatus of this embodiment generates an image signal based on the spectrum width (for example, the half-value width of the spectrum) between two frequency components having a predetermined intensity with respect to the center frequency component of the spectrum of the beat signal. ing. As apparent from (1) to (4) of FIG. 11, such a spectral width becomes larger as the fluid flow velocity becomes faster. For example, an image signal that takes a larger value as the spectral width becomes larger. Can be generated by clearly distinguishing the arterial portion and the vein portion from each other by density and brightness.

  The spectral width such as the half-value width is compensated for the above-described attenuation due to absorption or scattering of the measurement light, and basically changes as described above according to only the blood flow velocity. In addition, the arterial portion and the venous portion can be distinguished.

Imaging apparatus vascular that by the present invention, but are not necessarily utilizes optical heterodyne detection system, when the living body measurement light is irradiated, the spectrum spread is caused by the interaction with the living body the regimen photometry Focusing on this, the arteries and / or veins of the living body are imaged based on this spectral spread, so the arteries and / or veins are imaged in the same manner as when using the optical heterodyne detection system described above. Is possible.

  In the blood vessel imaging apparatus according to the present invention described above, the arteries and / or veins are imaged based on the spectral spread of the measurement light due to the interaction with the living body. A spectral spread corresponding to the blood flow rate of venous blood will be detected. Therefore, based on this spectrum broadening, it is possible to distinguish between an artery and a vein, and it is also possible to measure the blood flow rate of arterial blood or venous blood.

  The blood vessel identification device according to the present invention can identify an artery and a vein by the above mechanism. The scattering fluid flow velocity measuring apparatus according to the present invention is adapted to measure the flow velocity by applying the above-described mechanism for measuring blood flow velocity of arterial blood or venous blood to the flow velocity measurement of the entire scattering fluid.

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

<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. A band-pass filter 14 that is connected to the device 13 and passes only a signal in a band described later, and a level measuring device 15 that is connected to the band-pass filter 14.

  The imaging apparatus comprises a personal computer 20 that receives the output of the level measuring device 15 and constitutes an image signal generating means together with the level measuring device 15, and a CRT display device connected to the personal computer 20, for example. And an image monitor 21.

  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.

  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.

  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.

  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.

  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 of the photodetector 13 that receives the combined measurement light L includes the beat signal I based on the beat component, and the output is input to the bandpass filter 14.

  The beat signal I indicates the intensity of only the linear component of the measurement light L transmitted 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 I, high spatial resolution is ensured despite the measurement light L being scattered in the subject 22.

  The band pass filter 14 passes a signal in a band in the vicinity of a frequency (ω + Δf) that deviates from the center frequency ω of the beat signal I by a predetermined width Δf, as indicated by a curve c in FIG. The signal that has passed through the band-pass filter 14, that is, the center shift beat signal Io, is input to the level measuring device 15. The level measuring device 15 measures a predetermined level, such as a peak level, of the center-shift beat signal Io, and inputs a signal SL indicating the level to the personal computer 20.

  The personal computer 20 compares the level indicated by the signal SL with a predetermined threshold value as indicated by d in FIG. 5, and when the level exceeds the threshold value, the image signal Sp carrying a relatively high density (low luminance). When the level is equal to or lower than the threshold value, an image signal Sp carrying a background having a relatively low density (high luminance) is generated, and the image signal Sp is input to the image monitor 21.

  The level measuring device 15 outputs a center shift beat signal Io for each scanning position of the subject 22 along with the scanning of the measuring 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.

  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 excluding the vein portion of the subject 22. The reason is as described in detail with reference to FIG.

  On the other hand, in the personal computer 20, the level indicated by the signal SL is compared with a predetermined threshold value as indicated by d in FIG. 5, and when the level falls below the threshold value, a relatively high density (low luminance) is carried. If the image signal Sp is generated, and if the level is equal to or higher than the threshold value, the image signal Sp carrying a relatively low density (high luminance) background is generated, and the image is reproduced based on the image signal Sp, the image is A vein image of the subject 22 is obtained.

Second Embodiment
Next, a second embodiment of the present invention will be described. FIG. 2 shows a schematic configuration of a blood vessel imaging apparatus according to the second embodiment of the present invention. In FIG. 2, the same elements as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted unless necessary (the same applies hereinafter).

  Compared with the apparatus shown in FIG. 1, the apparatus of the second embodiment uses a pulse wave signal detector 50 that detects a pulse wave of the subject 22 and a level measurement signal SL output from the level measuring device 15 as a pulse. This is basically different in that a synchronization detection unit 51 that performs sampling based on the pulse wave signal Sc from the wave signal detection unit 50 is provided.

  Based on the pulse wave signal Sc, the synchronization detection unit 51 samples the level measurement signal SL when the spectrum spread due to the pulsation of the beat signal I is in a substantially constant phase (in this example, when the highest blood flow of the artery occurs). Then, it is input to the personal computer 20. If such synchronous detection is performed, the center-shifted beat signal Io of the beat signal I is at the time of the curve a-1 where the spectrum spread of the beat signal I is far from the curve b (spectrum spread due to venous blood flow) in FIG. The level is detected. As a result, the arterial portion can be clearly distinguished from the vein portion and imaged.

<Third Embodiment>
Next, a third embodiment of the present invention will be described. FIG. 3 shows a schematic configuration of a blood vessel imaging apparatus according to the third embodiment of the present invention. Compared with the apparatus shown in FIG. 2, the apparatus of the third embodiment replaces the pulse wave signal detection unit 50 with a photodetector 63 that receives the measurement light L synthesized by the half mirror 33, This is basically different in that a band-pass filter 64 connected to the photodetector 63 and passing only a signal in a band described later is provided, and a level measuring device 65 connected to the band-pass filter 64 is provided. is there.

  The bandpass filter 64 passes a signal in a band near the center frequency ω of the beat signal I included in the output of the photodetector 63. The signal Iω that has passed through the band pass filter 64 is input to the level measuring device 65. The level measuring device 65 outputs a timing signal St when the peak level of the signal Iω falls below a certain set value, and this timing signal St is input to the synchronization detecting unit 51. The synchronization detection unit 51 samples the level measurement signal SL output from the level measuring device 15 at the time when the timing signal St is input, and causes the personal computer 20 to input it.

  By performing such synchronous detection, also in this example, the level measurement signal SL is obtained when the spectrum spread due to the pulsation of the beat signal I has a substantially constant phase (in this example, when the maximum blood flow of the artery occurs). Sampling is possible. Therefore, the level of the center-shift beat signal Io is detected at the time when the beat signal I is in the state of the curve a-1 where the spectrum spread of the beat signal I is far from the curve b (spectrum spread due to venous blood flow) in FIG. Can be clearly identified from the vein portion and imaged.

<Fourth embodiment>
FIG. 7 is a schematic configuration diagram showing a blood vessel imaging device according to a fourth embodiment of the present invention. The apparatus of this embodiment includes a laser 111 that emits measurement light L having a wavelength λ, an optical heterodyne optical system 112, and photodetectors 113, 114, and 115 that receive the measurement light L emitted from the optical heterodyne optical system 112; The band-pass filters 116, 117, and 118, which are connected to the photodetectors 113, 114, and 115, respectively, and pass only signals in the bands described later, and the band-pass filters 116, 117, and 118, respectively. It has connected level measuring instruments 119, 120 and 121.

  The imaging apparatus includes a personal computer 122 serving as an image signal generating unit that receives the outputs of the level measuring devices 119, 120, and 121, and an image monitor 123 that is connected to the personal computer 122 and includes, for example, a CRT display device. have.

  Furthermore, an XY stage 125 is provided that can place a subject (for example, a human finger) 124 that is a blood vessel imaging target and can move in a two-dimensional direction. The XY stage 125 is driven by a stage driver 126, and the operation of the stage driver 126 is controlled by the personal computer 122.

  The optical system 112 that constitutes the optical heterodyne detection system together with the photodetectors 113, 114, and 115 includes a half mirror 130 that branches the measurement light L emitted from the laser 111 into two systems, and the measurement light that is reflected and branched here. A mirror 131 that reflects L and enters the subject 124, a mirror 132 that reflects the measurement light L transmitted through the half mirror 130, and the measurement light L reflected by the mirror 132 pass through the subject 124. A half mirror 133 that combines with the incoming measurement light L and enters the photodetector 113, a half mirror 135 that partially reflects the combined measurement light L and enters the photodetector 114, and this half mirror 135 The mirror 136 is configured to reflect the transmitted measurement light L and to enter the photodetector 115.

  In the optical path of the measurement light L that has passed through the half mirror 130, a frequency shifter 134 that is composed of, for example, AOM and applies a predetermined frequency shift of the center frequency ω to the measurement light L is inserted.

  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 124, the subject 124 is irradiated with the measurement light L emitted from the laser 111. At the same time, the XY stage 125 is driven so that the measurement light L scans the subject 124 two-dimensionally.

  When the measurement light L transmitted through the subject 124 and the measurement light L to which the frequency shift is given by the frequency shifter 134 are combined by the half mirror 133, the combined measurement light L has a beat having the same center frequency ω as the shift frequency. Ingredients are included. The outputs of the photodetectors 113, 114, and 115 that receive the combined measurement light L include the beat signal I based on the beat component, and the outputs are input to the bandpass filters 116, 117, and 118, respectively. Is done.

  The spectrum of the beat signal I is roughly as shown by the curve a or b in FIG. The curves a and b respectively show the spectra when the measurement light L passes through the arterial part and the vein part. As described above with reference to FIG. 11, the peak value of the beat signal I and the Doppler broadening of the spectrum are more noticeable when the blood passes through an artery portion having a higher blood flow velocity.

  The beat signal I indicates the intensity of only the linear component of the measurement light L that has passed through the subject 124, which is a scattering medium, and the scattering component close thereto. Therefore, if an image related to the subject 124 is obtained based on the beat signal I, high spatial resolution is ensured despite the measurement light L being scattered in the subject 124.

  The band-pass filter 116 passes a signal in a band near the center frequency ω of the beat signal I as indicated by a curve c in FIG. On the other hand, the band pass filter 117 passes a signal in a band in the vicinity of the center deviation frequency (ω + Δf2) deviated by a predetermined width Δf2 from the center frequency ω of the beat signal I to the high frequency side as indicated by the curve d in FIG. It is something to be made. Further, the band pass filter 118 has a band in the vicinity of the center deviation frequency (ω−Δf3) deviated by a predetermined width Δf3 from the center frequency ω of the beat signal I to the low frequency side as indicated by the curve e in FIG. A signal is allowed to pass through. Δf2 and Δf3 are set so as to satisfy the relationship of Δf2> Δf3.

  The outputs of the bandpass filters 116, 117 and 118 are input to level measuring devices 119, 120 and 121, respectively. These level measuring devices 119, 120 and 121 measure the intensity (for example, the maximum value) of a predetermined level of the input signal, respectively, and measure the measured signal strengths I (ω), I (ω + 2Δf) and I (ω− 3Δf) is input to the personal computer 122.

  The personal computer 122 obtains an intensity ratio I (ω + 2Δf) / I (ω) based on each input signal when an arterial image display is instructed, and the higher the intensity ratio, the higher the density (low luminance). An image signal Sp to be carried is generated, and the image signal Sp is input to the image monitor 123. When an image is displayed on the image monitor 123 based on such an image signal Sp generated for each scanning position of the measurement light L, an image in which the arterial portion is shown at a high density (low luminance) is obtained. The reason is as described in detail with reference to FIG.

  The personal computer 122 obtains the intensity ratio I (ω-3Δf) / I (ω) when the vein image display is instructed, and the image signal Sp carrying a higher density (lower luminance) as the intensity ratio is smaller. The image signal Sp is generated and input to the image monitor 123. If an image is displayed on the image monitor 123 based on such an image signal Sp generated for each scanning position of the measurement light L, an image in which the vein portion is shown at a high density (low luminance) is obtained.

  It is also possible to show only the arterial part or only the venous part as a binary image by thresholding the values of the intensity ratios I (ω + 2Δf) / I (ω) and (ω-3Δf) / I (ω). is there. However, according to the above embodiment, the flow velocity distribution of the blood flow is also displayed as a difference in image density, so that the clinical utility value is higher.

  It is also possible to switch and display an arterial image and a vein image using only one of the intensity ratios I (ω + 2Δf) / I (ω) and (ω-3Δf) / I (ω). In other words, for example, when an arterial image display is instructed, a vein image display is instructed so that the higher the intensity ratio I (ω + 2Δf) / I (ω) is, the higher the density (low luminance) is carried. The method of generating the image signal Sp may be switched so that the higher the intensity ratio I (ω + 2Δf) / I (ω) is, the higher the density (low luminance) is carried.

  However, according to the above embodiment, the image signal Sp carrying the vein image is generated from the value of the intensity ratio I (ω + 2Δf) / I (ω) that is extremely small (close to zero), or on the contrary, it is extremely large ( The image signal Sp carrying the arterial image is not generated from the value of the intensity ratio I (ω-3Δf) / I (ω) close to 1), and the handling of the signal is facilitated.

<Fifth Embodiment>
Next, a fifth embodiment of the present invention will be described. FIG. 9 shows a schematic configuration of a blood vessel imaging apparatus according to the fifth embodiment of the present invention.

  In the apparatus of the fifth embodiment, the measurement light L that has been frequency-shifted by the frequency shifter 134 and the measurement light L that has passed through the subject 124 are combined by the half mirror 133, and one light passes through the mirror 136. Guided to detector 115. The beat signal I output from the photodetector 115 is input to the frequency analyzer 150, and the output of the frequency analyzer 150 is input to the personal computer 122.

  The frequency analyzer 150 obtains the spectrum of the beat signal I and obtains the half width (full width at half maximum) W of the spectrum. As shown in FIG. 10, the half-value width W is a spectrum width between two points at which the intensity becomes ½ with respect to the component of the center frequency ω that takes the peak value of the beat signal I. The frequency analyzer 150 inputs a signal SW indicating the half width W to the personal computer 122.

  Based on this signal SW, the personal computer 122 generates an image signal Sp that carries a higher density (lower luminance) as the half-value width W is larger, and causes the image monitor 123 to input the image signal Sp. When an image is displayed on the image monitor 123 based on such an image signal Sp generated for each scanning position of the measurement light L, the arterial portion is shown at a relatively high density and the vein portion is shown at a relatively low density. An image is obtained. The reason is as described in detail above.

  In this case as well, by performing threshold processing on the signal SW, it is possible to obtain a binary image showing only the arterial part and a binary image showing only the vein part.

<Sixth Embodiment>
Next, a sixth embodiment of the present invention will be described. FIG. 13 shows a schematic configuration of the scattering fluid flow velocity measuring apparatus according to the sixth embodiment of the present invention.

  This flow velocity measuring device includes a laser 201 as a light irradiating means for irradiating the scattered fluid 200 flowing at a flow velocity v, a frequency analyzing means 202, and a signal constituting the flow velocity analyzing means together with the frequency analyzing means 202. And analysis means 203. The frequency analysis means 202 includes a condenser lens 210 that collects the measurement light L scattered by the scattering fluid 200, a collimator lens 211 that collimates the measurement light L collected by the condenser lens 210, A condensing lens 212 that condenses the measurement light L that has been collimated by the collimator lens 211, a photodetector 213 that detects the condensing measurement light L, the collimator lens 211, and the condensing lens 212 And a pair of half mirrors 220 and 221 constituting a Fabry-Perot interferometer.

  The half mirror 220 is fixed, but the other half mirror 221 is movable in the direction of arrow H in the figure by a driving means (not shown). The signal analysis means 203 is composed of a computer system, to which the light detection signal SQ output from the light detector 213 is input.

  Hereinafter, the operation of the apparatus of the present embodiment having the above configuration will be described. When measuring the flow velocity of the scattering fluid 200, the scattering fluid 200 is irradiated with the measurement light L. The measurement light L scattered by the scattering fluid 200 is guided to the photodetector 213 through the condenser lens 210, the collimator lens 211, and the condenser lens 212, and the light quantity is detected by the photodetector 213. At that time, light of a wavelength (that is, optical frequency) that generates a standing wave between the half mirror 221 and another half mirror 220 is intensified by interference, and the measurement light L of the optical frequency is detected by the photodetector 213. The Moreover, since the distance between the half mirror 221 and another half mirror 220 is continuously changed by moving the half mirror 221 in one direction, the frequency of light detected by the photodetector 213 is continuously changed. To do.

Therefore, the light detection signal SQ output from the light detector 213 indicates the detected light intensity E for each optical frequency in synchronization with the driving of the half mirror 221. The relationship between the optical frequency and the detected light intensity E is basically as shown in (1), (2), (3) and (4) of FIG. Here, (1) in the figure shows the case where the flow velocity v of the scattering fluid 200 is zero, and (2), (3) and (4) show the flow velocity v = v ₁ , v ₂ and v ₃ (v ₁ <v ₂ <v ₃ ).

  That is, also in this case, as in the case of the beat signal shown in FIG. 4, the spectrum spread of the measurement light L due to the interaction between the scattering fluid 200 and the measurement light L is recognized, and the flow velocity v is large as shown in FIG. The more the peak value of the detected light intensity E is lowered, the more the spectrum spread becomes larger. That is, there is a relationship as shown in FIG. 15 between the full width at half maximum FWHM across the center frequency ν of this spectrum and the flow velocity v. Upon receiving the light detection signal SQ, the signal analysis means 203 first obtains the spectral half-value width FWHM, and from this, obtains the flow velocity v based on the relationship between the half-value width FWHM and the flow velocity v obtained in advance from experience or experiment. The obtained flow velocity v is displayed on a display means (not shown) composed of, for example, a phototube or a liquid crystal panel.

  In the above example, the flow velocity v is obtained based on the detected spectral half-value width FWHM of the measurement light L. However, in order to obtain the flow velocity v using the spectral broadening of the measurement light L, other methods are used. You can also. For example, the light detection signal SQ output from the photodetector 213 is converted into a pass characteristic as indicated by a curve c 1 in FIG. 16, that is, a band pass filter having a pass characteristic in which the center frequency deviates from the center frequency ν of the measurement light L by + Δν. It is also possible to detect the intensity of the frequency component (center-shift frequency component) that has passed therethrough, and obtain the flow velocity v based on this intensity. That is, the intensity of the center-shift frequency component increases as the spectrum spread of the measurement light L increases, in other words, as the flow velocity v increases, and the flow velocity v can be obtained based on this relationship.

  As shown in FIG. 17, in the spectrum of the measurement light L indicated by the light detection signal SQ, the light intensity E (ν) of the component of the central frequency ν of the measurement light L and the light intensity E () of the component of the frequency (ν + Δν). ν + Δν) and the flow velocity v can be obtained based on the intensity ratio E (ν + Δν) / E (ν). That is, the intensity ratio E (ν + Δν) / E (ν) increases as the spectrum spread of the measurement light L increases, in other words, as the flow velocity v increases, as shown in FIG. Based on this, the flow velocity v can be determined.

  Although one embodiment of the scattering fluid flow velocity measuring apparatus has been described above, the flow velocity measuring apparatus of the present invention can be configured to measure the flow velocity from the beat component detection signal output from the above-described optical heterodyne detection system. It is. For example, the beat signal I output from the photodetector 115 in the blood vessel imaging device shown in FIG. 9 is transmitted through a scattering fluid having a higher flow velocity v as described above with reference to FIG. However, the decrease in the peak value and the Doppler broadening of the spectrum are more prominent. Therefore, the spectral half-value width W (see FIG. 10) of the beat signal I obtained by the frequency analyzer 150 increases as the flow velocity v of the scattered fluid increases. Can be requested.

  Further, in the spectrum of the beat signal I output by the photodetector 115, as shown in FIG. 11, the signal intensity I (ω) of the component of the center frequency ω and the signal intensity I (ω + Δf) of the component of the frequency (ω + Δf) are shown. And the flow velocity v can be obtained based on the intensity ratio I (ω + Δf) / I (ω). That is, the intensity ratio I (ω + Δf) / I (ω) increases as the Doppler spread of the spectrum of the beat signal I increases, in other words, as the flow velocity v increases. From this, the flow velocity v can be obtained.

  Further, for example, in the blood vessel imaging apparatus shown in FIG. 3, the level measurement signal SL sampled and output by the synchronization detection unit 51 passes through the scattered fluid having a higher flow velocity v as described with reference to FIG. If you do, you are at a higher level. Therefore, the flow velocity v can be obtained from the level measurement signal SL based on this relationship.

1 is a schematic configuration diagram showing a blood vessel imaging device according to a first embodiment of the present invention. Schematic configuration diagram showing a blood vessel imaging device according to a second embodiment of the present invention. Schematic configuration diagram showing a blood vessel imaging device according to a third embodiment of the present invention. Schematic showing changes in Doppler spread of beat signal due to fluid flow velocity Graph showing the spread of the spectrum of the beat signal due to blood flow and the pass characteristics of the filter that detects the misaligned beat signal Graph showing the spread of the spectrum of the beat signal due to blood flow and the pass characteristics of the filter that detects the misaligned beat signal Schematic configuration diagram showing a blood vessel imaging device according to a fourth embodiment of the present invention. Graph showing spread of spectrum of beat signal due to blood flow and pass characteristic of filter for detecting center-shifted beat signal in apparatus of fourth embodiment above. Schematic configuration diagram showing a blood vessel imaging device according to a fifth embodiment of the present invention. Schematic explaining the half width of the beat signal required in the apparatus of the fifth embodiment Schematic showing changes in Doppler spread of beat signal due to fluid flow velocity Graph showing the relationship between the fluid flow velocity and the intensity ratio of the center offset frequency component to the center frequency component of the beat signal The schematic block diagram which shows the flow velocity measuring apparatus of the scattering fluid by 6th Embodiment of this invention. Schematic diagram showing the change in the spectrum of the measurement light that has passed through the scattering fluid, depending on the fluid flow velocity, along with the spectrum half-width Graph showing the relationship between the half-width of the spectrum of the measurement light that has passed through the scattering fluid and the fluid flow velocity Graph showing the spectrum of the measurement light that has passed through the scattering fluid and the pass characteristics of the filter that detects the center-shift frequency component Schematic showing the change in the spectrum of the measurement light that has passed through the scattering fluid, depending on the fluid flow velocity, along with the off-center frequency. A graph showing the relationship between the fluid flow velocity and the intensity ratio of each component of the center frequency of the measurement light passing through the scattering fluid and the frequency deviating from the center frequency

11 Laser
12 Optical heterodyne optical system
13 photodetector
14 Bandpass filter
15 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
63 photodetector
64 band pass filter
65 level measuring instrument
111 laser
112 Optical heterodyne optical system
113, 114, 115 Photodetector
116, 117, 118 Band pass filter
119, 120, 121 level measuring instruments
122 Personal computer
123 Image monitor
124 subjects
125 XY stage
126 Stage driver
130, 133, 135 Half mirror
131, 132, 136 mirrors
134 Frequency shifter
150 frequency analyzer
200 Scattered fluid
201 laser
202 Frequency analysis means
203 Signal analysis means
210, 212 condenser lens
211 collimator lens
213 photodetector
220, 221 half mirror

Claims (15)

A light irradiation means for irradiating a living body with measurement light;
A blood vessel imaging apparatus comprising imaging means for imaging arteries and / or veins of a living body based on a spectrum spread of the irradiated measurement light due to interaction with the living body. The imaging means detects a frequency component of the measurement light scattered by the living body, detects a half width of a spectrum of the frequency component detection signal, and images the artery and / or vein based on the half width. The blood vessel imaging apparatus according to claim 1, wherein: The imaging means detects a frequency component of the measurement light scattered by the living body, detects an intensity of a center-shift frequency component that deviates from a center frequency of the frequency component detection signal, and based on the intensity, 2. The blood vessel imaging device according to claim 1 , wherein the blood vessel imaging device is for imaging an artery and / or a vein. The imaging means detects a frequency component of the measurement light scattered by the living body, and calculates a ratio between the intensity of the center frequency component of the frequency component detection signal and the intensity of the frequency component deviating from the center frequency by a predetermined width. 2. The blood vessel imaging device according to claim 1 , wherein the blood vessel imaging device detects and images the artery and / or vein based on the ratio. The blood vessel imaging according to any one of claims 1 to 4 , wherein the imaging means detects a frequency component of the measurement light scattered by the living body based on an optical heterodyne detection signal. apparatus. A light irradiation means for irradiating a living body with measurement light;
A blood vessel identification device comprising identification means for identifying an artery and a vein of a living body based on a spectrum spread of the irradiated measurement light due to interaction with the living body. The identifying means detects a frequency component of the measurement light scattered by the living body, detects a half width of a spectrum of the frequency component detection signal, and identifies the artery and vein based on the half width. The blood vessel identification device according to claim 6 , wherein the blood vessel identification device is provided. The identification unit detects a frequency component of the measurement light scattered by the living body, detects an intensity of a center-shift frequency component that deviates from a center frequency of the frequency component detection signal by a predetermined width, and based on the intensity, the artery 7. The blood vessel identification device according to claim 6 , wherein the blood vessel identification device identifies a vein and a vein. The identification means detects the frequency component of the measurement light scattered by the living body, and detects the ratio between the intensity of the center frequency component of the frequency component detection signal and the intensity of the frequency component deviating from the center frequency by a predetermined width. 7. The blood vessel identification device according to claim 6, wherein the artery and vein are identified based on the ratio. The blood vessel identification device according to claim 6 , wherein the identification unit detects a frequency component of the measurement light scattered by the living body based on an optical heterodyne detection signal. A light irradiation means for irradiating the scattering fluid with measurement light;
An apparatus for measuring a flow velocity of a scattered fluid, comprising: analysis means for analyzing the flow velocity of the scattered fluid based on a spectrum spread of the irradiated measurement light by interaction with the scattered fluid. The analysis means detects a frequency component of the measurement light scattered by the fluid, detects a half width of a spectrum of the frequency component detection signal, and analyzes the flow velocity based on the half width. 12. The scattering fluid flow velocity measuring device according to claim 11, wherein The analysis means detects the frequency component of the measurement light scattered by the fluid, detects the intensity of a center-shifted frequency component that deviates from a center frequency of the frequency component detection signal, and based on the intensity, the flow velocity 12. The apparatus for measuring a flow velocity of a scattering fluid according to claim 11, wherein: The analysis means detects the frequency component of the measurement light scattered by the fluid, and detects the ratio between the intensity of the center frequency component of the frequency component detection signal and the intensity of the frequency component deviating from the center frequency by a predetermined width. 12. The apparatus for measuring a flow velocity of a scattering fluid according to claim 11, wherein the flow velocity is analyzed based on the ratio. 15. The flow velocity measurement of a scattered fluid according to claim 11 , wherein the analyzing means detects a frequency component of the measurement light scattered by the fluid based on an optical heterodyne detection signal. apparatus.