JP6453191B2 - Blood flow measuring device - Google Patents

Description

  The present invention relates to a blood flow measuring device.

  Optical coherence tomography (OCT) is used not only for measuring the form of an object but also for measuring its function. For example, an apparatus for measuring blood flow of a living body using OCT is known. Blood flow measurement using OCT is applied to fundus blood vessels and the like.

JP2013-184018A JP 2009-165710 A Special table 2010-523286

  In general, in order to acquire blood flow information using OCT, it is necessary to estimate the direction of a blood vessel to be measured. This is because the blood flow information is obtained based on the Doppler frequency shift that changes in accordance with the angle between the incident direction of the measurement light with respect to the living body and the blood flow direction (blood vessel direction). In the conventional blood flow measurement technology, blood flow information is obtained by separately performing measurement for estimating the direction of a blood vessel and Doppler OCT, or performing Doppler OCT on two cross sections. .

  However, such a conventional configuration has a demerit that it takes time for measurement. For example, blood flow information is generally collected over a period of one heartbeat or more, so Doppler OCT is performed for a sufficient period (eg, 2 seconds). Therefore, when the measurement for estimating the direction of the blood vessel and the Doppler OCT are performed separately, the time required for the former measurement and the time required for the Doppler OCT are required. In addition, when Doppler OCT is performed on two cross sections, Doppler OCT must be executed twice.

  In addition, when the object is accompanied by movement, such as when the object is a living eye, the object moves between the measurement for estimating the direction of the blood vessel and Doppler OCT, or between two Doppler OCTs, The reliability of the required blood flow information may be reduced.

  An object of the present invention is to improve the reliability of blood flow measurement.

The blood flow measurement device according to the embodiment includes a scanning unit, an image forming unit, and an image processing unit. Using the optical coherence tomography, the scanning unit repeatedly scans one cross section intersecting the target blood vessel of the living body, and sequentially and repeatedly scans a plurality of cross sections intersecting the target blood vessel. The image forming unit forms a phase image representing a temporal change in the phase difference in one cross section based on data acquired by scanning one cross section, and based on data acquired by scanning a plurality of cross sections. Thus, images of each of a plurality of cross sections are formed. The image processing unit calculates the inclination of the blood vessel of interest in one cross section based on images formed for a plurality of cross sections, and generates blood flow information related to the blood vessel of interest based on the phase image and the inclination of the blood vessel of interest. The image forming unit forms a plurality of images for each of the plurality of sections based on data acquired by scanning the plurality of sections. The image processing unit obtains a temporal change in the inclination of the target blood vessel based on the plurality of images formed for each of the plurality of cross sections, and determines the timing based on one frame of the phase image and the inclination at the corresponding timing. Blood flow information is generated.

  According to this invention, it is possible to improve the reliability of blood flow measurement.

It is a schematic diagram showing an example of composition of a blood flow measuring device concerning an embodiment. It is a schematic diagram showing an example of composition of a blood flow measuring device concerning an embodiment. It is a schematic diagram showing an example of composition of a blood flow measuring device concerning an embodiment. It is a schematic diagram showing an example of composition of a blood flow measuring device concerning an embodiment. It is a schematic diagram showing an example of operation of a blood flow measuring device concerning an embodiment. It is a schematic diagram showing an example of operation of a blood flow measuring device concerning an embodiment. It is a flowchart showing an example of operation | movement of the blood-flow measuring device which concerns on embodiment. It is a schematic diagram showing an example of operation of a blood flow measuring device concerning an embodiment.

  Exemplary embodiments of the present invention will be described in detail with reference to the drawings. In addition, the description content of the literature referred in this specification can be used for embodiment.

  The blood flow measurement device acquires information related to blood flow of a living body using OCT. Moreover, the blood flow measuring device can acquire an image of a living body using OCT. Hereinafter, a case where blood flow measurement of the fundus is performed using Fourier domain OCT (particularly, spectral domain OCT) will be described. Note that the target of blood flow measurement need not be the fundus but may be any living body such as skin or internal organs. Further, the type of OCT is not limited to the spectral domain OCT, and may be any type such as a swept source OCT or a time domain OCT. In the following embodiments, an apparatus that combines an OCT apparatus and a fundus camera will be described. For example, an embodiment in which an OCT apparatus is combined with an SLO (Scanning Laser Ophthalmoscope), a slit lamp, an ophthalmic surgical microscope, etc. It is possible to apply a configuration similar to the above. Further, the same configuration as that of the embodiment can be applied to an apparatus having only the OCT function.

[Constitution]
As shown in FIG. 1, the blood flow measurement device 1 includes a fundus camera unit 2, an OCT unit 100, and an arithmetic control unit 200. The fundus camera unit 2 has a configuration for photographing the fundus oculi Ef. The OCT unit 100 has a configuration for acquiring an OCT image of the fundus oculi Ef. The arithmetic control unit 200 has a configuration for executing various calculations and controls.

[Fundus camera unit]
The fundus camera unit 2 acquires a two-dimensional image (fundus image) representing the surface form of the fundus oculi Ef. The fundus image includes an observation image and a captured image. The observation image is a monochrome moving image acquired at a predetermined frame rate using near infrared light, for example. The captured image includes a color image obtained by flashing visible light, a monochrome image obtained using near infrared light or visible light (for example, a fluorescein fluorescent image, an indocyanine green fluorescent image, a spontaneous fluorescent image, etc. Fluorescent image).

  The fundus camera unit 2 is provided with an illumination optical system 10 and a photographing optical system 30. The illumination optical system 10 irradiates the eye E with illumination light. The imaging optical system 30 detects return light (fundus reflected light, corneal reflected light, fluorescence, etc.) of illumination light from the eye E to be examined. Further, the fundus camera unit 2 guides the measurement light from the OCT unit 100 to the eye E, and guides the return light of the measurement light from the eye E to the OCT unit 100.

  The light (observation illumination light) output from the observation light source 11 of the illumination optical system 10 is reflected by the reflection mirror 12 having a curved reflecting surface, passes through the condensing lens 13 and passes through the visible cut filter 14. Near infrared light. Further, the observation illumination light is once converged in the vicinity of the photographing light source 15, reflected by the mirror 16, passes through the relay lenses 17 and 18, the diaphragm 19 and the relay lens 20, and then the peripheral portion (hole portion) of the aperture mirror 21. ), Is reflected by the dichroic mirror 46, is refracted by the objective lens 22, and is applied to the eye E.

  The return light of the observation illumination light from the eye E is refracted by the objective lens 22, passes through the dichroic mirror 46, passes through the hole formed in the central region of the perforated mirror 21, and passes through the dichroic mirror 55. Then, the light passes through the focusing lens 31, is reflected by the mirror 32, passes through the half mirror 40, is reflected by the dichroic mirror 33, and forms an image on the light receiving surface of the area sensor 35 by the condenser lens 34. The area sensor 35 detects return light at a predetermined frame rate. Thereby, observation images of the fundus oculi Ef and the anterior eye segment are obtained.

  The light (imaging illumination light) output from the imaging light source 15 is irradiated to the eye E (fundus Ef) through the same path as the observation illumination light. The return light (fundus reflection light, fluorescence, etc.) of the imaging illumination light is guided to the dichroic mirror 33 through the same path as that of the observation illumination light, passes through the dichroic mirror 33, is reflected by the mirror 36, and is collected by the condenser lens. 37 forms an image on the light receiving surface of the area sensor 38. Thereby, a captured image such as the fundus oculi Ef is obtained.

  An LCD (Liquid Crystal Display) 39 displays a fixation target and an eyesight measurement target. A part of the light output from the LCD 39 is reflected by the half mirror 40, reflected by the mirror 32, passes through the focusing lens 31 and the dichroic mirror 55, passes through the hole of the perforated mirror 21, and is dichroic. The light passes through the mirror 46, is refracted by the objective lens 22, and is projected onto the eye E (fundus Ef). By changing the display position of the fixation target by the LCD 39, the fixation position of the eye E can be changed.

  The fundus camera unit 2 is provided with an alignment optical system 50 and a focus optical system 60. The alignment optical system 50 generates an index (alignment index) for performing alignment (alignment) of the apparatus optical system with respect to the eye E. The focus optical system 60 generates an index (split index) for focusing on the fundus oculi Ef.

  Near-infrared light (alignment light) output from the LED 51 of the alignment optical system 50 is reflected by the dichroic mirror 55 via the apertures 52 and 53 and the relay lens 54, and passes through the hole of the aperture mirror 21. The light passes through the dichroic mirror 46 and is projected onto the eye E (cornea) by the objective lens 22. The return light of the alignment light is detected by the area sensor 35 through the same path as the return light of the observation illumination light. A detection image (alignment index image) by the area sensor 35 is drawn in the observation image. The user or the arithmetic control unit 200 can perform alignment based on the position of the alignment index image, similarly to the conventional fundus camera.

  When performing the focus adjustment, the reflecting surface of the reflecting rod 67 is obliquely provided in the optical path of the illumination optical system 10. Near-infrared light (focus light) output from the LED 61 of the focus optical system 60 passes through the relay lens 62, is separated into two light beams by the split indicator plate 63, passes through the two-hole aperture 64, and reaches the mirror 65. The light is reflected, once formed on the reflecting surface of the reflecting rod 67 by the condenser lens 66, reflected, reflected by the aperture mirror 21 via the relay lens 20, transmitted through the dichroic mirror 46, and refracted by the objective lens 22. And projected onto the eye E (fundus Ef). The return light of the focus light is detected by the area sensor 35 through the same path as the return light of the alignment light. The detection image (split indicator image) by the area sensor 35 is drawn in the observation image. The user or the arithmetic control unit 200 performs focusing by moving the focusing lens 31 and the focus optical system 60 based on the position of the split index image, similarly to the conventional fundus camera. The focusing lens 31 is moved by a focusing drive unit 31A shown in FIG. 3, and the focus optical system 60 is moved by a driving mechanism (not shown).

  After the alignment (and focusing) is completed, tracking for moving the apparatus optical system in accordance with the eye movement of the eye E to be examined can be executed.

  The dichroic mirror 46 synthesizes an optical path for fundus imaging and an optical path for OCT measurement (referred to as a measurement arm or a sample arm). The dichroic mirror 46 reflects light in a wavelength band used for OCT measurement and transmits light for fundus photographing. In the OCT measurement optical path, a collimator lens unit 40, an optical path length changing unit 41, an optical scanner 42, a focusing lens 43, a mirror 44, and a relay lens 45 are provided in this order from the OCT unit 100 side. ing.

  The optical path length changing unit 41 changes the length of the measurement arm. The optical path length changing unit 41 includes, for example, a corner cube that can move in the direction of the arrow shown in FIG. The change of the optical path length of the measurement arm is used for adjusting the optical path length according to the axial length of the eye E or adjusting the interference state.

  The optical scanner 42 has a configuration capable of two-dimensionally deflecting light passing through the measurement arm (measurement light LS). For example, the optical scanner 42 is configured to be able to scan the measurement light LS independently in directions orthogonal to each other (x direction and y direction). Thereby, various scanning patterns are realized. In addition, when the configuration for the anterior segment OCT (lens system attachment or the like) is applied, the anterior segment is scanned with the measurement light LS. The optical scanner 42 includes, for example, a galvanometer mirror, a MEMS mirror, a resonant mirror, and the like.

[OCT unit]
FIG. 2 shows a configuration example of the OCT unit 100. The OCT unit 100 has a configuration corresponding to the type of OCT. FIG. 2 shows an example of a configuration when the spectral domain OCT is applied. In the spectral domain OCT, a low-coherence light source and a spectroscope are generally provided. In the swept source OCT, for example, a wavelength swept light source and a balanced photodiode are provided.

  In the spectral domain OCT, the light L0 output from the light source unit 101 is broadband low-coherence light. The light L0 includes, for example, a near-infrared wavelength band (about 800 nm to 900 nm) and has a temporal coherence length of about several tens of micrometers. For example, near infrared light having a center wavelength of about 1040 to 1060 nm may be used as the light L0. The light source unit 101 includes a light output device such as a super luminescent diode (SLD), an LED, or an SOA (Semiconductor Optical Amplifier).

  The light L0 output from the light source unit 101 is guided to the fiber coupler 103 by the optical fiber 102 and is divided into the measurement light LS and the reference light LR.

  The reference light LR is guided by the optical fiber 104 and reaches the optical attenuator (attenuator) 105. The optical attenuator 105 automatically adjusts the amount of the reference light LR guided to the optical fiber 104 under the control of the arithmetic control unit 200 using a known technique. The reference light LR whose light amount has been adjusted by the optical attenuator 105 is guided by the optical fiber 104 and reaches the polarization adjuster 106. The polarization adjuster 106 adjusts the polarization state of the reference light LR guided to the optical fiber 104 under the control of the arithmetic control unit 200 using a known technique. The reference light LR whose polarization state has been adjusted reaches the fiber coupler 109.

  On the other hand, the measurement light LS generated by the fiber coupler 103 is guided by the optical fiber 107 and converted into a parallel light beam by the collimator lens unit 105. Further, the measurement light LS is reflected by the dichroic mirror 46 via the optical path length changing unit 41, the optical scanner 42, the focusing lens 43, the mirror 44, and the relay lens 45, and is refracted by the objective lens 11 to be examined eye E. Irradiates (fundus Ef). The measurement light LS is scattered and reflected at various depth positions of the fundus oculi Ef. The return light (backscattered light, reflected light, fluorescence, etc.) of the measurement light LS travels in the same direction as the forward path in the reverse direction, is guided to the fiber coupler 103, and reaches the fiber coupler 109 via the optical fiber 108. . The focusing lens 43 is moved by a focusing drive unit (not shown).

  The fiber coupler 109 causes the return light of the measurement light LS to interfere with the reference light LR that has passed through the fiber coupler 104. The interference light LC thus generated is guided by the optical fiber 110 and emitted from the emission end 111, converted into a parallel light beam by the collimator lens 112, dispersed (spectral decomposition) by the diffraction grating 113, and collected by the condenser lens 114. The light is projected onto the light receiving surface of the photodetector 115. The photodetector 115 is, for example, a line sensor, and detects each spectral component of the separated interference light LC to generate an electrical signal (detection signal). The generated detection signal is sent to the arithmetic control unit 200.

[Calculation control unit]
The arithmetic control unit 200 executes control of the fundus camera 2, the display device 3, and the OCT unit 100, various arithmetic processes, OCT image formation processing, and the like. The arithmetic control unit 200 includes a user interface such as a display device, an input device, and an operation device. The configuration of the arithmetic control unit 200 will be described in the following description of the control system of the control system.

[Control system]
A control system of the blood flow measurement device 1 will be described with reference to FIGS. 3 and 4.

(Control part)
The control system of the blood flow measurement device 1 is configured with a control unit 210 as a center. The control unit 210 is provided with a main control unit 211 and a storage unit 212.

(Main control unit)
The main control unit 211 controls the fundus camera unit 2, the OCT unit 100, and the arithmetic control unit 200. Further, the main control unit 211 performs processing for writing data into the storage unit 212 and processing for reading data from the storage unit 212.

(Memory part)
The storage unit 212 stores various data. Examples of data stored in the storage unit 212 include an OCT image, a fundus image, and eye information to be examined. The eye information is information about the eye or the subject and includes, for example, input information such as a patient ID and medical information such as an electronic medical record. The storage unit 212 stores a program and data for operating the blood flow measurement device 1.

(Image forming part)
The image forming unit 220 forms tomographic image data and phase image data of the fundus oculi Ef based on the detection signal from the photodetector 115. These image data will be described later. In this specification, “image data” and “image” output based on the “image data” may be identified. The image forming unit 220 includes a tomographic image forming unit 221 and a phase image forming unit 222.

  In this embodiment, two types of scanning (first scanning and second scanning) are performed on the fundus oculi Ef. In the first scan, the first cross section that intersects the target blood vessel of the fundus oculi Ef is repeatedly scanned with the measurement light LS. In the second scan, the second cross section intersecting with the blood vessel of interest is scanned with the measurement light LS. The second cross section is set in the vicinity of the first cross section. Here, the first cross section and the second cross section are preferably oriented so as to be orthogonal to the traveling direction of the blood vessel of interest. Moreover, it is desirable that the first cross section and the second cross section are set in parallel to each other. Specific examples of the first cross section and the second cross section are shown in FIG. A fundus image D shown in FIG. 5 shows a first cross section C0 and a second cross section C1 set in the vicinity of the optic disc Da of the fundus oculi Ef. The first cross section C0 and the second cross section C1 are set so as to intersect the predetermined target blood vessel Db. The second cross section C1 may be set on the upstream side of the target blood vessel Db with respect to the first cross section C0, or may be set on the downstream side.

  The first and second scans are preferably performed over at least one cardiac cycle of the patient's heart. Thereby, blood flow information in all time phases of the heart is obtained. The time for executing the first scan may be a predetermined time set in advance, or may be a time set for each patient or for each examination. In the former case, a time longer than a general cardiac cycle is set (for example, 2 seconds). In the latter case, examination data such as a patient's electrocardiogram is referred to. Here, factors other than the cardiac cycle can be considered. Examples of this factor include time required for examination (a burden on the patient), response time (scan interval) of the optical scanner 42, response time (scan interval) of the photodetector 115, and the like.

(Tomographic image forming part)
The tomographic image forming unit 221 forms a tomographic image (first tomographic image) representing the temporal change of the form in the first cross section based on the detection result of the interference light LC obtained by the first scanning. This process will be described in more detail. In the first scanning, the first cross section C0 is repeatedly scanned as described above. Detection signals are sequentially input from the photodetector 115 of the OCT unit 100 to the tomographic image forming unit 221 in accordance with the first scan. The tomographic image forming unit 221 forms one tomographic image of the first cross section C0 based on the detection signal corresponding to each scan of the first cross section C0. The tomographic image forming unit 221 forms a series of tomographic images along a time series by repeating the above-described processing as many times as the first scan is repeated. Here, these tomographic images may be divided into a plurality of groups, and the tomographic images of each group may be superimposed (added and averaged) to improve the image quality.

  In addition, the tomographic image forming unit 221 forms a tomographic image (second tomographic image) representing the form in the second cross section C1 based on the detection result of the interference light LC obtained by the second scanning with respect to the second cross section C1. This process is executed in the same manner as in the case of the first tomogram. The first tomographic image is a series of tomographic images along time series, but the second tomographic image may be a single tomographic image. The second tomographic image may be an image obtained by superimposing (addition averaging) a plurality of tomographic images obtained by scanning the second cross section C1 a plurality of times to improve the image quality.

  The processing for forming such a tomographic image includes processing such as noise removal (noise reduction), filter processing, FFT (Fast Fourier Transform), and the like, similarly to the conventional spectral domain type optical coherence tomography. In the case of another type of OCT apparatus, the tomographic image forming unit 221 executes a known process corresponding to the type.

(Phase image forming unit)
The phase image forming unit 222 forms a phase image representing the change over time of the phase difference in the first cross section based on the detection result of the interference light LS obtained by the first scanning. The detection result used in this process is the same as that used for the first tomographic image forming process by the tomographic image forming unit 221. Therefore, it is possible to perform alignment between the first tomographic image and the phase image. That is, it is possible to naturally associate the pixels of the first tomographic image with the pixels of the phase image.

  An example of a phase image forming method will be described. The phase image in this example is obtained by calculating the phase difference between adjacent A-line complex signals (signals corresponding to adjacent scanning points). In other words, the phase image of this example is formed based on the temporal change of the pixel value (luminance value) of each pixel of the first tomographic image. For any pixel, the phase image forming unit 222 considers a graph of the change in luminance value over time. The phase image forming unit 222 obtains a phase difference Δφ between two time points t1 and t2 (= t1 + Δt) separated by a predetermined time interval Δt in this graph. The phase difference Δφ is defined as the phase difference Δφ (t1) at the time point t1 (more generally, any time point between the two time points t1 and t2). By executing this process for each of a number of preset time points, the temporal change of the phase difference in the pixel can be obtained.

  The phase image represents the value of the phase difference at each time point of each pixel as an image. This imaging process can be realized, for example, by expressing the value of the phase difference with the display color or brightness. At this time, the display color (for example, red) when the phase increases along the time series and the display color (for example, blue) when it decreases can be changed. Also, the magnitude of the phase change amount can be expressed by the darkness of the display color. By adopting such an expression method, the direction and size of the blood flow can be clearly indicated by the display color. A phase image is formed by executing the above processing for each pixel.

  The change in the phase difference with time can be obtained by sufficiently reducing the time interval Δt to ensure phase correlation. At this time, oversampling in which the time interval Δt is set to a value less than the time corresponding to the resolution of the tomographic image in the scanning of the measurement light LS is executed.

(Image processing unit)
The image processing unit 230 performs various types of image processing and analysis processing on the image formed by the image forming unit 220. For example, the image processing unit 230 executes various correction processes such as image brightness correction and dispersion correction. The image processing unit 230 performs various types of image processing and analysis processing on the image (fundus image, anterior eye image, etc.) obtained by the fundus camera unit 2.

  The image processing unit 230 includes a blood vessel region specifying unit 231, an inclination calculating unit 232, and a blood flow information generating unit 233. The blood flow information generation unit 233 includes a blood flow velocity calculation unit 234, a blood vessel diameter calculation unit 235, and a blood flow rate calculation unit 236. Further, the image processing unit 230 has a cross-section setting unit 237. Hereinafter, each of these units 231 to 237 will be described.

(Vessel region specific part)
The blood vessel region specifying unit 231 specifies a blood vessel region corresponding to the target blood vessel Db for each of the first tomographic image, the second tomographic image, and the phase image. This processing can be performed by analyzing the pixel value of each image (for example, threshold processing).

  It should be noted that the first tomogram and the second tomogram have sufficient resolution to perform analysis processing, but the phase image may not have enough resolution to identify the boundary of the blood vessel region. However, as long as blood flow information is generated based on the phase image, it is necessary to specify the blood vessel region with high accuracy and high accuracy. Therefore, for example, by performing the following processing, the blood vessel region of the phase image can be specified more accurately.

  As described above, the first tomographic image and the phase image are formed based on the same detection signal, and natural association between the pixels is possible. Using this, first, the first tomogram is analyzed to obtain a blood vessel region, and an image region in a phase image composed of pixels corresponding to the pixels included in this blood vessel region is set as the blood vessel region. Thereby, the blood vessel region of the phase image can be specified with high accuracy and high accuracy.

(Inclination calculator)
The inclination calculation unit 232 calculates the inclination of the target blood vessel Db in the first cross section based on the distance between the first cross section and the second cross section (inter-section distance) and the result of specifying the blood vessel region. The distance between the cross sections is determined in advance. One example will be described later in the description of the cross-section setting unit 237.

  The reason for calculating the inclination of the target blood vessel Db will be described. Blood flow information is obtained by the Doppler OCT technique. The blood flow velocity component contributing to the Doppler shift is a component in the irradiation direction of the measurement light LS. Therefore, even if the blood flow velocity is the same, the Doppler shift received by the measurement light LS changes according to the angle formed by the blood flow direction (that is, the direction of the blood vessel Db of interest) and the measurement light LS, and thus blood obtained Flow information will also change. In order to avoid such inconvenience, it is necessary to obtain the inclination of the target blood vessel Db and reflect this in the blood flow velocity calculation process.

  A method of calculating the inclination of the target blood vessel Db will be described with reference to FIG. Reference sign G0 indicates a first tomogram in the first section C0, and reference sign G1 indicates a second tomogram in the second section C1. Reference sign V0 indicates a blood vessel region in the first tomographic image G0, and reference sign V1 indicates a blood vessel region in the second tomographic image G1. In FIG. 6, the z coordinate axis is directed downward in the drawing, and this substantially coincides with the irradiation direction of the measurement light LS. The distance between the cross sections is indicated by d.

  The inclination calculation unit 232 calculates the inclination A of the target blood vessel Db in the first cross section C0 based on the positional relationship between the two blood vessel regions V0 and V1. This positional relationship is obtained, for example, by connecting two blood vessel regions V0 and V1. More specifically, the inclination calculating unit 232 specifies the feature positions of the two blood vessel regions V0 and V1, and connects the two specified feature positions with line segments. Examples of the characteristic position include a center position, a center of gravity position, an uppermost portion (a position having the smallest z coordinate value), and a lowermost portion (a position having the largest z coordinate value).

  Further, the inclination calculation unit 232 calculates the inclination A based on the line segment connecting the two feature positions. More specifically, the inclination calculation unit 232 calculates the inclination of the line segment connecting the feature position of the first cross section C0 and the feature position of the second cross section C1, and sets the calculated value as the inclination A. Note that the cross-sectional distance d is used when the two tomographic images G0 and G1 are embedded in the xyz coordinate system in the process of obtaining the line segment.

  In this example, one inclination value is obtained, but the inclination may be obtained for each of two or more positions (or regions) in the blood vessel region V0. In this case, two or more obtained slope values can be used separately, or one value (for example, an average value) statistically obtained from these slope values can be used as the slope A.

(Blood flow information generator)
The blood flow information generation unit 233 generates blood flow information related to the target blood vessel Db based on the phase image and the inclination A of the target blood vessel Db. Hereinafter, an example of a configuration for executing this process will be described. As described above, the blood flow information generation unit 233 includes the blood flow velocity calculation unit 234, the blood vessel diameter calculation unit 235, and the blood flow rate calculation unit 236.

(Blood velocity calculation part)
The blood flow velocity calculation unit 234 calculates the blood flow velocity in the first cross section C0 of the blood flowing in the target blood vessel Db based on the phase image (change in the phase difference with time) and the inclination A of the target blood vessel Db. This calculation target may be a blood flow velocity at a certain point in time, or a change in blood flow velocity over time (blood flow velocity change information). In the former case, for example, it is possible to selectively acquire the blood flow velocity in a predetermined time phase (for example, R wave time phase) of the electrocardiogram. The time range in the latter is the entire time or a part of the time when the first cross section C0 is scanned.

  When the blood flow velocity change information is obtained, the blood flow velocity calculator 234 can calculate a statistical value of the blood flow velocity in the time range. The statistical values include an average value, standard deviation, variance, median value, maximum value, minimum value, maximum value, minimum value, and the like. It is also possible to create a histogram for blood flow velocity values.

  The blood flow velocity calculation unit 234 calculates the blood flow velocity using the Doppler OCT method as described above. At this time, the inclination A of the target blood vessel Db in the first cross section C0 calculated by the inclination calculation unit 232 is taken into consideration. Specifically, the blood flow velocity calculation unit 234 uses the following equation to obtain the blood flow velocity.

here:
Δf represents the Doppler shift received by the scattered light of the measurement light LS;
n represents the refractive index of the medium;
v represents the flow velocity (blood flow velocity) of the medium;
θ represents the angle formed by the irradiation direction of the measurement light LS and the flow vector of the medium;
λ represents the center wavelength of the measurement light LS.

  In this embodiment, n and λ are known, Δf is obtained from the phase change over time, and θ is obtained from the slope A (or θ is obtained as the slope A). By substituting these values into the above formula, the blood flow velocity v is calculated.

  In consideration of changes in parameters over time, the Doppler shift Δf = Δf (t) and the angle θ = θ (t) are expressed. Here, t is a variable representing time. The blood flow velocity calculation unit 234 can obtain a blood flow velocity v (t) at an arbitrary time t or obtain a change in blood flow velocity v (t) over time by using the following equation.

(Vessel diameter calculator)
The blood vessel diameter calculation unit 235 calculates the diameter of the target blood vessel Db in the first cross section C0. Examples of this calculation method include a first calculation method using a fundus image and a second calculation method using a tomographic image.

  When the first calculation method is applied, imaging of a part of the fundus oculi Ef including the position of the first cross section C0 is performed in advance. The fundus image obtained thereby may be an observation image (frame) or a captured image. When the captured image is a color image, an image constituting the captured image (for example, a red free image) may be used.

  The blood vessel diameter calculation unit 235 determines the relationship between the scale on the image and the scale in the real space, such as the shooting angle of view (shooting magnification), working distance, and information on the eyeball optical system. Set the scale. This scale represents the length in real space. As a specific example, this scale is obtained by associating an interval between adjacent pixels with a scale in real space (for example, an interval between pixels = 10 μm). It is also possible to calculate in advance the relationship between various values of the above factor and the scale in the real space, and store information expressing this relationship in a table format or a graph format. In this case, the blood vessel diameter calculation unit 235 selectively applies a scale corresponding to the factor.

  Furthermore, the blood vessel diameter calculation unit 235 calculates the diameter of the target blood vessel Db in the first cross section C0, that is, the diameter of the blood vessel region V0, based on this scale and the pixels included in the blood vessel region V0. As a specific example, the blood vessel diameter calculation unit 235 obtains the maximum value and the average value of the diameters of the blood vessel region V0 in various directions. In addition, the blood vessel region 235 can approximate the outline of the blood vessel region V0 in a circle or an ellipse, and obtain the diameter of the circle or the ellipse. If the blood vessel diameter is determined, the area of the blood vessel region V0 can be (substantially) determined (that is, the two can be substantially associated one-to-one). You may make it calculate.

  A second calculation method will be described. In the second calculation method, a tomographic image of the fundus oculi Ef in the first cross section C0 is used. The tomographic image may be a first tomographic image, a phase image, or may be obtained separately from these.

  The scale in this tomographic image is determined according to the scanning mode of the measurement light LS. In this embodiment, the first cross section C0 is scanned as shown in FIG. The length of the first cross section is determined based on various factors that determine the relationship between the scale on the image and the scale in the real space, such as working distance and information on the eyeball optical system. For example, the blood vessel diameter calculation unit 235 obtains the interval between adjacent pixels based on this length, and calculates the diameter of the blood vessel Db of interest in the first cross section C0 in the same manner as in the first calculation method. The change over time of the blood vessel diameter can also be obtained.

(Blood flow calculation unit)
The blood flow rate calculation unit 236 calculates the flow rate of the blood flowing in the target blood vessel Db based on the blood flow velocity calculation result and the blood vessel diameter calculation result. An example of this process will be described below.

  It is assumed that the blood flow in the blood vessel is a Hagen-Poiseille flow. Further, when the blood vessel diameter is w and the maximum value of the blood flow velocity is Vm, the blood flow rate Q is expressed by the following equation.

  The blood flow rate calculation unit 236 substitutes the calculation result w of the blood vessel diameter by the blood vessel diameter calculation unit 235 and the maximum value Vm based on the calculation result of the blood flow velocity by the blood flow velocity calculation unit 234 into this equation. A target blood flow rate Q is calculated. As another method, the blood flow rate can be calculated by integrating the product (or integrated value) of the change in blood flow rate with time and the blood vessel diameter (change with time) over time. The unit of blood flow is, for example, μL / min.

(Cross section setting part)
The main control unit 211 causes the display unit 241 to display a fundus image. This fundus image may be an observation image or a captured image. Further, the fundus image may be an image constituting a captured image. The user operates the operation unit 242 to designate the first cross section C0 for the displayed fundus image. The cross section setting unit 237 sets the second cross section C1 based on the designated first cross section C0 and the fundus image. As described above, the first cross section CO is designated so as to cross the desired blood vessel Db.

  The operation of designating the first cross section C0 as a fundus image is performed using, for example, a pointing device. When the display unit 241 is a touch panel, the user can specify the first cross section C0 by touching a desired position of the displayed fundus image. In this case, the parameters (direction, length, etc.) of the first cross section C0 are set manually or automatically.

  As an example of manual operation, a predetermined interface for setting parameters can be used. This interface may be hardware such as a switch or software such as a graphical user interface (GUI).

  As an example of an automatic case, the cross-section setting unit 237 sets parameters based on the position designated by the user for the fundus image. For the automatic length setting, a predetermined value may be applied, or the designated position and the position of a blood vessel in the vicinity thereof may be considered. The former value is designated based on, for example, a general distance between a predetermined blood vessel of interest and a blood vessel in the vicinity thereof. This distance information can be generated based on clinical data. The same applies to the latter case. In any case, the length of the first cross section C0 is set so as to cross the target blood vessel Db and not cross the other blood vessels (particularly thick blood vessels).

  For automatic setting of the orientation of the first cross section C0, a predetermined orientation may be applied, or the orientation of the target blood vessel Db may be taken into account. In the former case, information indicating the inclination of each position of a predetermined blood vessel of interest is generated in advance and is referred to. This information can be generated based on clinical data. In the latter case, the traveling direction of the target blood vessel Db at the designated position is obtained and set based on the traveling direction. The process for obtaining the traveling direction is performed using, for example, a thinning process for the blood vessel Db of interest. In any case, it is desirable that the direction of the first cross section C0 is set to be orthogonal to the traveling direction.

  Next, a process for setting the second cross section C1 will be described. The cross-section setting unit 237 sets the second cross-section C1 at a position away from the first cross-section C0 by a predetermined distance. This distance is set to 100 μm, for example. This distance is specified as described above, for example. The length and / or direction of the second cross section C1 is set in the same manner as in the case of the first cross section C0.

  In this embodiment, the cross sections C0 and C1 (that is, the scanning position of the measurement light LS) are set based on the fundus image. For this purpose, it is necessary to associate the fundus image with the scanning position. As for this association, as in this embodiment, it is desirable that the fundus imaging optical system and the OCT measurement optical system share a part of each other's optical path. With this coaxial configuration, the position in the fundus image and the scanning position can be associated with each other based on the optical axis. In this association, fundus image display magnification (including at least one of so-called optical zoom and digital zoom) may be taken into consideration.

  In the case of such a coaxial configuration, the fundus image and the scanning position can be associated based on the fundus image and the projection image obtained by OCT measurement. Note that the projection image is an image representing the form of the surface of the fundus oculi Ef obtained by integrating three-dimensional images obtained by three-dimensional scanning (raster scanning) in the depth direction (z direction). By using such a projection image, the position between the fundus image and the projection image can be associated using, for example, image correlation, and the fundus image and the scanning position can be associated using this association. However, in consideration of the influence of eye movement (fixed eye movement, etc.) of the eye E, it is considered that a coaxial configuration capable of performing both imaging substantially without time lag is desirable.

  The image processing unit 230 that functions as described above includes, for example, the aforementioned microprocessor, RAM, ROM, hard disk drive, circuit board, and the like. In a storage device such as a hard disk drive, a computer program for causing the microprocessor to execute the above functions is stored in advance.

(User interface)
The user interface 240 includes a display unit 241 and an operation unit 242. The display unit 241 includes the display device of the arithmetic control unit 200 and the display device 3 described above. The operation unit 242 includes the operation device of the arithmetic control unit 200 described above. The operation unit 242 may include various buttons and keys provided on the housing of the blood flow measurement device 1 or outside. For example, when the fundus camera unit 2 has a housing similar to that of a conventional fundus camera, the operation unit 242 may include a joystick, an operation panel, or the like provided on the housing. Further, the display unit 241 may include various display devices such as a touch panel provided in the housing of the fundus camera unit 2.

  The display unit 241 and the operation unit 242 do not need to be configured as individual devices. For example, a device in which a display function and an operation function are integrated, such as a touch panel, can be used. In that case, the operation unit 242 includes the touch panel and a computer program. The operation content for the operation unit 242 is input to the control unit 210 as an electrical signal. Further, operations and information input may be performed using the GUI displayed on the display unit 241 and the operation unit 242.

[Operation]
The operation of the blood flow measuring device 1 will be described. FIG. 7 shows an example of the operation of the blood flow measurement device 1.

(S1: Preparation for measurement)
As preparation for OCT measurement, input of a patient ID, selection designation of an operation mode (blood flow measurement mode) of this embodiment, and the like are performed. Subsequently, alignment and focusing are performed. In addition, tracking may be started. The display unit 241 displays a fundus image (an observation image, a captured image, or an image constituting the captured image).

(S2: Designation of measurement position)
Next, the user designates a position where blood flow is measured with respect to the displayed fundus image. The first section is designated here. The method for specifying the first cross section has been described above. Note that it is also possible to automatically specify the first cross section with reference to the characteristic part (optic nerve head or the like) of the fundus oculi Ef. This process includes, for example, a process for specifying a feature part, a process for specifying a target blood vessel, and a process for setting the first cross section so as to be separated from the feature part by a predetermined distance and intersect the target blood vessel. This series of processing is executed by the cross-section setting unit 237.

(S3: Setting of cross section near measurement position)
When the first cross section is designated, the cross section setting unit 237 sets the second cross section based on the first cross section.

(S4: Optimization of OCT measurement)
The main control unit 211 performs preliminary OCT measurement by controlling the light source unit 101, the optical scanner 42, and the like. This preliminary OCT measurement is performed on the first cross section, the second cross section, or other cross sections. It is determined whether the image obtained by this preliminary OCT is suitable. This determination may be performed visually by the user, or may be automatically performed by the blood flow measurement device 1.

  When performing the visual check, the main control unit 211 causes the display unit 241 to display the OCT image. The user evaluates the display position and image quality of a predetermined tissue (blood vessel, retina surface, etc.) in the OCT image. When a suitable image is not obtained, the user adjusts the measurement conditions. For example, when the image display position is not appropriate, the optical path length changing unit 41 is operated to change the optical path length of the measuring light LS. If the image quality is not appropriate, the optical attenuator 105 and the polarization adjuster 106 are adjusted.

  When performing automatically, the display position, image quality, and the like of a predetermined tissue are evaluated with reference to a predetermined evaluation standard, and measurement conditions are adjusted based on the evaluation result in the same manner as in the manual case.

(S5: Execution of OCT measurement)
The main control unit 211 starts OCT measurement (blood flow measurement) in response to a predetermined trigger. FIG. 8 shows an outline of processing executed in this operation example. Note that it is desirable that the tracking started in step S1 is continued while the OCT measurement of this step is being performed. Thereby, even if the eye E moves during OCT measurement, substantially the same position (first cross section and second cross section) can be scanned.

In this operation example, the first scan J1 for OCT measurement of the first cross section where blood flow is measured and the second scan J2 for OCT measurement of the second cross section in the vicinity of the first cross section are executed alternately. In the example shown in FIG. 8, a single first scan (one B scan of the first cross section) and a single second scan (one B scan of the second cross section) are executed alternately. . Thereby, the pair [J1, J2] ₁ of the data acquired in the first scan of the first time and the data acquired in the first scan of the second time, the data acquired in the first scan of the second time. And the data obtained in the second scan of the second time [J1, J2] ₂ ,..., Obtained in the first scan of the nth time and the second scan of the nth time. [J1, J2] _n with the data obtained. Data pairs [J1, J2] _i (i = 1 to n) correspond to times t _i (i = 1 to n), respectively. As each time t _i (i = 1 to n), for example, an arbitrary time within the period in which the OCT measurement for acquiring the data pair [J1, J2] _i (i = 1 to n) is performed is assigned. It is done. Note that one or more first scans and one or more second scans may be executed alternately.

(S6: Image formation)
The image forming unit 220 forms an image based on the data acquired in step S5. In this operation example, the tomographic image forming unit 221 uses the first tomographic image T1 _i (i = 1 to n) representing the first cross section based on each data pair [J1, J2] _i (i = 1 to n). And a second tomographic image T2 _i (i = 1 to n) representing the second cross section is formed. The first tomographic image T1 _i and the second tomographic image T2 _i (i = 1 to n) correspond to the time t _i (i = 1 to n).

Further, the phase image forming unit 222 performs data [J1] _i (i = 1 to n−1) related to the first cross section in each data pair [J1, J2] _i (i = 1 to n−1), and the next. Phase image P representing the first cross section based on the data [J1] _{i + 1} (i = 1 to n−1) related to the first cross section in the data pair [J1, J2] _{i + 1} (i = 1 to n−1). _i (i = 1 to n−1) is formed. The phase image P _i (i = 1 to n−1) corresponds to the time t _i (i = 1 to n−1). It is also possible to form a phase image of the second cross section by executing similar processing based on the data [J2] _i (i = 1 to n) regarding the second cross section.

In this operation example, the phase image P _n corresponding to the time t _n is not created. However, for example, the phase image P _n can be created by executing the (n + 1) th OCT measurement on the first cross section. Alternatively, the phase image P _n-1 may be copied to form the phase image P _n . It is also possible to apply an operation example in which the first tomographic image T1 _n and the second tomographic image T2 _n corresponding to the time t _n are not formed. In addition, a representative pair (or two or more pairs) based on any one (or two or more) representative data pairs among n data pairs [J1, J2] _i (i = 1 to n). The first tomographic image and the second tomographic image may be formed.

(S7: Identification of blood vessel region)
The blood vessel region specifying unit 231 specifies a blood vessel region corresponding to the target blood vessel for each of the first tomographic image T1 _i , the second tomographic image T2 _i, and the phase image P _i .

(S8: Calculation of inclination of target blood vessel)
The inclination calculation unit 232 calculates the inclination of the target blood vessel in the first cross section based on the blood vessel region specified in step S7 and the distance between the first cross section and the second cross section (inter-section distance). As a specific example of this processing, the inclination calculation unit 232 is identified from the first tomographic image T1 _i and the second tomographic image T2 _i (i = 1 to n) at each time t _i (i = 1 to n). Based on the two blood vessel regions and the cross-sectional distance, the inclination A _i (i = 1 to n) of the target blood vessel at the time t _i (i = 1 to n) can be calculated. Note that the blood vessel region specified from the phase image P _i can be used instead of the first tomographic image T1 _i . Further, instead of obtaining the inclination A _i (i = 1 to n) corresponding to each time t _i (i = 1 to n), one or more representative inclinations may be obtained. For example, the period of time t _{1 to} t _n is divided into one or more partial periods, and a statistical value (average value, median value, etc.) is calculated from a plurality of slopes A _i included in each partial period. It can be used as the inclination of the target blood vessel in the partial period.

(S9: Calculation of blood flow velocity)
The blood flow velocity calculation unit 234 changes the phase difference obtained as the phase image P _i (i = 1 to n−1) over time and the inclination A _i (i = 1 to n) of the target blood vessel calculated in step S8. ), The blood flow velocity v _i (i = 1 to n) in the first cross section of the blood flowing in the target blood vessel is calculated. The blood flow velocity v _i (i = 1 to n) corresponds to the time t _i (i = 1 to n), respectively. Incidentally, the blood flow velocity v _n in the case where the phase image P _n is not formed may not be calculated.

(S10: Calculation of blood vessel diameter)
Based on the first tomographic image T1 _i (i = 1 to n) (or P _i (i = 1 to n−1)), the blood vessel diameter calculation unit 235 calculates the diameter w _i (i of the target blood vessel in the first cross section). = 1 to n). Note that one or more representative blood vessel diameters may be obtained instead of obtaining the blood vessel diameter w _i (i = 1 to n) corresponding to each time t _i (i = 1 to n). Alternatively, the blood vessel diameter may be obtained by analyzing the fundus image instead of the first tomographic image. In addition to the blood vessel diameter of the first cross section, the blood vessel diameter of the second cross section can be obtained. In this case, generally, the blood vessel diameter of the first cross section is different from the blood vessel diameter of the second cross section.

(S11: Calculation of blood flow)
The blood flow rate calculation unit 236 calculates the flow rate Q (μL / min) of blood flowing in the target blood vessel based on the blood flow velocity calculated in step S9 and the blood vessel diameter calculated in step S10.

(S12: Display and storage of measurement results)
The main control unit 211 displays blood flow information including the blood flow velocity v _i calculated in step S9, the blood vessel diameter w _i calculated in step S10, the blood flow rate Q calculated in step S11, and the like on the display unit 241. Let Further, the main control unit 211 stores blood flow information in the storage unit 212 in association with the patient ID input in step S1. This is the end of the process related to this operation example.

[effect]
The effect of the blood flow measurement device according to the embodiment will be described.

  The blood flow measurement device according to the embodiment includes a scanning unit, an image forming unit, a blood vessel region specifying unit, an inclination calculating unit, and a blood flow information generating unit.

  The scanning unit alternately performs a first scan that scans a first cross section that intersects the target blood vessel of the living body and a second scan that scans a second cross section that intersects the target blood vessel using OCT. In the present embodiment, the scanning unit includes at least an optical system for performing OCT (for example, see the optical path of the measurement light LS shown in FIG. 1 and the optical system shown in FIG. 2).

  The image forming unit forms one or more first cross-sectional images including at least a phase image representing a temporal change in the phase difference in the first cross-section based on the data acquired by the first scan. The image of the first cross section other than the phase image may be an arbitrary image formed from data acquired by OCT. As an example, there is a first tomographic image representing the form of the first cross section (change over time). Further, the image forming unit forms an image of the second cross section based on the data acquired by the second scanning. As an example of the image of the second cross section, there is a second tomographic image representing the form of the second cross section (change over time). In the present embodiment, the image forming unit 220 functions as an image forming unit.

  The blood vessel region specifying unit specifies a first blood vessel region corresponding to the target blood vessel in the first cross-sectional image formed by the image forming unit. Furthermore, the blood vessel region specifying unit specifies a second blood vessel region corresponding to the target blood vessel in the second cross-sectional image. In the present embodiment, the blood vessel region specifying unit 231 functions as a blood vessel region specifying unit.

  The inclination calculation unit calculates the inclination of the target blood vessel in the first cross section based on the first blood vessel region and the second blood vessel region specified by the blood vessel region specifying unit. In the present embodiment, the inclination calculation unit 232 functions as an inclination calculation unit.

  The blood flow information generation unit generates blood flow information related to the target blood vessel based on the phase image formed by the image forming unit and the inclination of the target blood vessel calculated by the inclination calculation unit. In the present embodiment, the blood flow information generation unit 233 functions as a blood flow information generation unit.

  According to such a blood flow measurement device, it is possible to measure two cross sections alternately and obtain blood flow information by obtaining the inclination of the blood vessel based on the data obtained thereby. On the other hand, in the conventional technique, blood flow information is obtained by separately performing measurement for estimating the inclination of the blood vessel and Doppler OCT, or by performing Doppler OCT on two cross sections. Yes. Therefore, according to the present embodiment, blood flow measurement can be performed in a shorter time than conventional. Further, in the present embodiment, since a configuration in which the first scan and the second scan are alternately executed (that is, a configuration in which these are executed in parallel) is adopted, it is (almost) affected by the motion of the target. It is possible to acquire blood flow information with high reliability.

In the embodiment, the inclination calculation unit can obtain a change with time in the inclination of the blood vessel of interest (A _i (i = 1 to n)). Moreover, blood flow information generating unit, based on the inclination (A _i) at the timing (time t _i) corresponding thereto and one frame of the phase image (P _i), blood flow in the timing (time t _i) Information can be generated. This blood flow information may include, for example, at least one of a blood flow velocity v _i , a blood vessel diameter w _i, and a blood flow rate Q.

More specifically, the inclination calculation unit is executed immediately before or immediately after the data ([J1] _i ) acquired by the first scan executed at one timing (time t _i ). the second on the basis of the data obtained by scanning (e.g. _{[J2] i-1} or _{[J2] i),} and calculates the inclination of the target vessel _{(a i)} in the one of the timing (time _{t i)} that was Can do. Furthermore, the blood flow information generation unit is configured to generate the one based on the frame (P _i ) of the phase image corresponding to the one timing (time t _i ) and the inclination (A _i ) of the target blood vessel at the one timing. Blood flow information at the timing (time t _i ) can be generated.

  According to such a configuration, blood flow information at the timing can be acquired from the calculation result of the inclination at each timing even when the inclination of the blood vessel of interest changes due to the movement of the living body or the like. Thereby, it is possible to further improve the reliability of the acquired blood flow information. Such actions and effects are achieved by alternately executing the first scan and the second scan.

In the embodiment, the blood flow information generation unit changes with time (v _i (i = 1 to n) the blood flow velocity in the first cross section of the blood flowing in the target blood vessel based on the phase image and the inclination of the target blood vessel. )) To obtain a blood flow velocity calculation unit (234). According to this configuration, at least the blood flow velocity can be acquired as the blood flow information.

Furthermore, in the embodiment, the blood flow information generation unit may include a blood vessel diameter calculation unit (235) and a blood flow rate calculation unit (236). The blood vessel diameter calculating unit calculates the diameter (w _i ) of the blood vessel of interest in the first cross section based on the first blood vessel region specified by the blood vessel region specifying unit. The blood flow rate calculation unit calculates the flow rate (Q) of the blood flowing in the target blood vessel based on the change over time in the blood flow velocity (v _i (i = 1 to n)) and the diameter (w _i ) of the target blood vessel. calculate. According to this configuration, it is possible to acquire a blood flow rate as blood flow information.

In addition, the blood vessel diameter calculation unit can obtain a change with time in the diameter of the blood vessel of interest (w _i (i = 1 to n)). In this case, the blood flow rate calculation unit, a time course of blood flow velocity and _{(v i (i = 1~n)} ), and changes over time in the diameter of the target vessel _{(w i (i = 1~n)} ) Based on this, it is possible to calculate the flow rate (Q) of blood flowing in the blood vessel of interest. According to this configuration, it is possible to improve the reliability of the calculated blood flow rate.

  Note that the number of blood vessels of interest is not limited to one, and may be two or more. In addition, two or more blood vessels of interest may be included in the pair of first and second cross sections. When two or more attention blood vessels are considered, the processing of this embodiment is executed for each attention blood vessel. Thereby, blood flow information (e.g., the inclination of the blood vessel, the blood vessel diameter, the blood flow velocity, the blood flow amount) regarding each blood vessel of interest is acquired.

[Modification]
The configuration described above is merely an example for favorably implementing the present invention. Therefore, arbitrary modifications (omitted, replacement, addition, etc.) within the scope of the present invention can be made as appropriate.

  A modified example of the blood flow calculation method will be described. In this modification, the blood flow velocity calculation unit 234 generates information (blood flow velocity change information) that represents a change in blood flow velocity over time for each pixel included in the blood vessel region of the phase image. In this process, for example, a process of associating a plurality of phase image pixels along the time series for each pixel position, and generating blood flow velocity change information based on the plurality of pixels along the time series corresponding to each pixel position. And processing to be performed. By this processing, the blood flow velocity in the blood vessel region of the first cross section can be obtained for each position.

  The blood flow rate calculation unit 236 calculates the blood flow rate for each pixel by integrating the blood flow rate change information of each pixel included in the blood vessel region along a time series. By this process, the blood flow rate in the blood vessel region of the first cross section can be obtained for each position.

  Furthermore, the blood flow rate calculation unit 236 can calculate the flow rate of blood flowing through the target blood vessel by adding the blood flow rates for these pixels. By this process, the blood flow volume at each position obtained in the previous process is added, and the total amount of blood flowing through the blood vessel region of the first cross section is obtained.

  In the above embodiment, the optical path length difference between the optical path of the measurement light LS and the optical path of the reference light LR is changed by changing the position of the optical path length changing unit 41, but this optical path length difference is changed. The method is not limited to this. For example, it is possible to change the optical path length difference by disposing a reflection mirror (reference mirror) in the optical path of the reference light and moving the reference mirror in the traveling direction of the reference light to change the optical path length of the reference light. Is possible. Further, the optical path length difference may be changed by moving the fundus camera unit 2 or the OCT unit 100 with respect to the eye E to change the optical path length of the measurement light LS. In particular, when the measured object is not a living body part, the optical path length difference can be changed by moving the measured object in the depth direction (z direction).

DESCRIPTION OF SYMBOLS 1 Blood flow measuring apparatus 2 Fundus camera unit 41 Optical path length change part 42 Optical scanner 100 OCT unit 200 Operation control unit 210 Control part 211 Main control part 212 Storage part 220 Image formation part 221 Tomographic image formation part 222 Phase image formation part 230 Image Processing unit 231 Blood vessel region specifying unit 232 Inclination calculating unit 233 Blood flow information generating unit 234 Blood flow velocity calculating unit 235 Blood vessel diameter calculating unit 236 Blood flow rate calculating unit 237 Cross section setting unit 241 Display unit 242 Operation unit E Eye to be examined Ef Fundus

Claims (4)

Using optical coherence tomography, a scanning unit that repeatedly scans one cross section intersecting the target blood vessel of a living body, and sequentially and repeatedly scans a plurality of cross sections intersecting the target blood vessel,
Forming a phase image representing a change over time of the phase difference in the one cross section based on the data obtained by scanning the one cross section, and based on the data obtained by scanning the plurality of cross sections. An image forming unit that forms an image of each of a plurality of cross sections;
The inclination of the blood vessel of interest in the one cross section is calculated based on the images formed for the plurality of cross sections, and blood flow information relating to the blood vessel of interest is generated based on the phase image and the inclination of the blood vessel of interest. and an image processing unit,
The image forming unit forms a plurality of images for each of the plurality of cross sections based on data acquired by scanning the plurality of cross sections;
The image processing unit obtains a change in inclination of the blood vessel of interest over time based on the plurality of images formed for each of the plurality of cross sections, and the inclination at one frame of the phase image and the corresponding timing To generate blood flow information at the timing based on
A blood flow measuring device characterized by that . Wherein the image processing unit, based on the inclination of the target vessel and the phase image, claim 1, wherein the determination of the time course of blood flow velocity in the one section of the blood flowing through the interest in a blood vessel blood flow measuring apparatus according to. The image processing unit calculates a diameter of the blood vessel of interest in the one cross section based on data acquired by scanning the cross section of the one, and calculates a change in blood flow velocity over time and a diameter of the blood vessel of interest. The blood flow measuring device according to claim 2 , wherein a flow rate of blood flowing in the blood vessel of interest is calculated based on the blood flow. The image processing unit obtains a change over time in the diameter of the blood vessel of interest in the one cross section based on data acquired by scanning the cross section of the one, and changes the blood flow velocity over time and the blood vessel of the attention blood vessel. The blood flow measurement device according to claim 3 , wherein the flow rate is calculated based on a change in diameter with time.