JP2018046959A - Ophthalmologic photographing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a burden in optical coherence tomography (OCT) blood flow measurement.SOLUTION: A data collection part of an ophthalmologic photographing apparatus collects a three-dimensional data set on the ocular fundus of an eye to be examined using OCT. A blood vessel emphasis image forming part forms a blood vessel emphasis image based on the three-dimensional data set. A blood vessel angle distribution acquisition part acquires blood vessel angle distribution indicating an inclination angle of a blood vessel at one or more positions of the ocular fundus based on the blood vessel emphasis image. A measurement position setting part sets a measurement position as an object of OCT blood flow measurement based on the blood vessel angle distribution. A collection control part controls the data collection part so as to repeatedly scan a first cross section intersecting with the blood vessel at the measurement position. A blood flow information generation part generates blood flow information indicating a blood flow state in the blood vessel based on first data collected by repeatedly scanning the first cross section and the inclination angle of the blood vessel in the measurement position.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an ophthalmologic photographing apparatus.

  Image diagnosis occupies an important position in the field of ophthalmology. In recent years, utilization of optical coherence tomography (OCT) has been advanced. OCT has been used not only for acquiring B-mode images and three-dimensional images of the eye to be examined, but also for acquiring front images (en-face images) such as C-mode images and shadowgrams.

  Furthermore, acquiring the image which emphasized the specific site | part of the eye to be examined, and acquiring functional information are also performed. For example, based on time-series volume data collected by OCT, a B-mode image or a front image (blood vessel-enhanced image, angiogram) in which retinal blood vessels and choroidal blood vessels are emphasized can be constructed. This technique is called OCT Angiography. In addition, blood flow information can be acquired based on phase information of data collected by OCT. This technique is called OCT blood flow measurement.

Special table 2015-515894 gazette JP2013-184018A

  In OCT blood flow measurement, it is necessary to estimate the direction of a target blood vessel. This is because blood flow information is obtained using a Doppler frequency shift that changes according to the angle between the incident direction of the measurement light on the blood vessel and the direction of blood flow (the direction of the blood vessel). In order to perform OCT blood flow measurement with high accuracy, it is necessary to select a blood vessel with a suitable orientation.

  However, in the conventional technique, since the blood vessel is selected with reference to the frontal image of the fundus obtained by the fundus camera or SLO (Scanning Laser Ophthalmoscope), it is not possible to grasp the direction component of the blood vessel that affects the Doppler frequency shift. It was difficult. For this reason, time and labor are imposed on the examiner and the subject, such as searching for a suitable blood vessel by evaluating the direction of the blood vessel obtained by the preliminary measurement.

  An object of the present invention is to reduce the burden in OCT blood flow measurement.

  An ophthalmologic imaging apparatus according to an exemplary embodiment includes a data collection unit, a blood vessel enhancement image formation unit, a blood vessel angle distribution acquisition unit, a measurement position setting unit, a collection control unit, and a blood flow information generation unit. . The data collection unit collects a three-dimensional data set of the fundus of the eye to be examined using optical coherence tomography (OCT). The blood vessel emphasized image forming unit forms a blood vessel emphasized image based on the three-dimensional data set collected by the data collecting unit. The blood vessel angle distribution acquisition unit obtains a blood vessel angle distribution representing the inclination angle of the blood vessel at one or more positions of the fundus based on the blood vessel emphasized image formed by the blood vessel emphasized image forming unit. The measurement position setting unit sets a measurement position to be an object of OCT blood flow measurement based on the blood vessel angle distribution obtained by the blood vessel angle distribution acquisition unit. The collection control unit controls the data collection unit to repeatedly scan the first cross section that intersects the blood vessel at the measurement position set by the measurement position setting unit. The blood flow information generator generates blood in this blood vessel based on the first data collected by the data collector by repeated scanning of the first cross section and the inclination angle of the blood vessel at the measurement position set by the measurement position setting unit. Blood flow information representing a flow state is generated.

  According to the embodiment, it is possible to reduce the burden in OCT blood flow measurement.

Schematic showing the structure of an exemplary ophthalmologic imaging apparatus. Schematic showing the structure of an exemplary ophthalmologic imaging apparatus. Schematic for demonstrating the process which an exemplary ophthalmologic imaging apparatus performs. Schematic for demonstrating the process which an exemplary ophthalmologic imaging apparatus performs. The flowchart showing operation | movement of an exemplary ophthalmologic imaging apparatus. The flowchart showing operation | movement of an exemplary ophthalmologic imaging apparatus. Schematic for demonstrating operation | movement of an exemplary ophthalmologic imaging apparatus. The flowchart showing operation | movement of an exemplary ophthalmologic imaging apparatus. The flowchart showing operation | movement of an exemplary ophthalmologic imaging apparatus. Schematic showing the structure of an exemplary ophthalmologic imaging apparatus. The flowchart showing operation | movement of an exemplary ophthalmologic imaging apparatus. Schematic showing the structure of an exemplary ophthalmologic imaging apparatus. The flowchart showing operation | movement of an exemplary ophthalmologic imaging apparatus. Schematic showing the structure of an exemplary ophthalmologic imaging apparatus. The flowchart showing operation | movement of an exemplary ophthalmologic imaging apparatus.

  An exemplary embodiment of the present invention will be described with reference to the drawings. In addition, the matter described in the literature referred by this specification can be used for embodiment.

  Embodiments determine the angle of inclination of a blood vessel at one or more locations of the fundus using OCT angiography. By associating the position of the fundus with the inclination angle of the blood vessel, a distribution of the inclination angle of the fundus blood vessel (blood vessel angle distribution) is obtained. The blood vessel angle distribution can be used for diagnosis and other modalities, for example. A typical example of another modality is OCT blood flow measurement.

  The inclination angle of the blood vessel may be defined with reference to an arbitrary direction (angle = 0 degree). For example, the direction of A (Axial) scan (direction of A line) in OCT can be used as a reference. The reference direction of the inclination angle of the blood vessel may be set in common for all positions where the inclination angle is measured, or may be set for each position. Alternatively, all positions may be divided into two or more groups, and a reference direction may be set for each of these groups.

  In OCT angiography, substantially the same area of the fundus is repeatedly scanned, and a blood vessel-enhanced image is formed based on the obtained three-dimensional data set including a plurality of two-dimensional data sets. The three-dimensional data set, for example, scans a plurality of B sections (transverse sections) a predetermined number of times (for example, four times), and forms a predetermined number of images (B mode images) in each B section. Obtained by embedding in the same 3D coordinate system (and by voxelizing it). Such an image forming technique is known.

  The ophthalmologic photographing apparatus according to the embodiment includes an optical system, a drive system, a control system, and a data processing system for executing OCT. The ophthalmologic imaging apparatus of the embodiment is configured to be able to execute, for example, Fourier domain OCT.

  The Fourier domain OCT includes a spectral domain OCT and a swept source OCT. Spectral domain OCT is a technique for imaging a subject's eye by acquiring a spectrum of interference light by spatial division using a broadband low-coherence light source and a spectroscope and performing Fourier transform on the spectrum. Swept source OCT uses a wavelength-swept light source (wavelength variable light source) and a photodetector (balanced photodiode, etc.) to acquire the spectrum of interference light in a time-sharing manner, and Fourier transforms the eye to be examined. This is a technique for imaging. The method of OCT is not limited to Fourier domain OCT, but may be time domain OCT or unfaced OCT.

  The ophthalmologic imaging apparatus may include a modality (for example, a modality other than OCT) for imaging the eye and / or other parts. Typical examples include a fundus camera, SLO, a slit lamp microscope, and an ophthalmic surgical microscope. The ophthalmologic imaging apparatus may include a configuration for measuring the characteristics of the eyes and / or other parts and a configuration for performing an examination.

  The data processing function (calculation function, image processing function, control function, etc.) in the ophthalmic imaging apparatus according to the embodiment includes, for example, hardware such as a processor and a storage device, and software such as a calculation program, an image processing program, and a control program. Is realized through collaboration. A part of the hardware may be provided in an external device that can communicate with the ophthalmologic photographing apparatus. Further, at least a part of the software may be stored in advance in the ophthalmologic photographing apparatus and / or may be stored in advance in the external apparatus.

<First Embodiment of Ophthalmic Imaging Device>
<Constitution>
An exemplary embodiment of an ophthalmic imaging device will be described. A configuration example of the ophthalmologic photographing apparatus is shown in FIG. The ophthalmologic imaging apparatus 1 collects a three-dimensional data set of the fundus using OCT, forms a blood vessel emphasized image based on the three dimensional data set, obtains a blood vessel angle distribution based on the blood vessel emphasized image, A measurement position is set based on the angular distribution, and OCT blood flow measurement is performed at this measurement position. In this OCT blood flow measurement, the ophthalmologic imaging apparatus 1 repeatedly scans the first cross section intersecting the blood vessel at the set measurement position, and the first data collected thereby and the inclination angle of the blood vessel at the measurement position. Based on the above, blood flow information representing a blood flow state in the blood vessel is generated.

  The ophthalmologic photographing apparatus 1 can display the blood vessel angle distribution, information obtained therefrom, blood flow information, information obtained therefrom, and the like on the display device 2. The display device 2 may be a part of the ophthalmologic photographing apparatus 1 or may be an external device connected to the ophthalmic photographing apparatus 1. The ophthalmologic photographing apparatus 1 can send blood vessel angle distribution, information obtained therefrom, blood flow information, information obtained therefrom, and the like to a computer, a storage device, an ophthalmologic apparatus, and the like.

  The ophthalmologic photographing apparatus 1 includes a control unit 10, a storage unit 20, a data collection unit 30, a data processing unit 40, an operation unit 50, and a front image acquisition unit 60.

<Control unit 10>
The control unit 10 controls each unit of the ophthalmologic photographing apparatus 1. The control unit 10 includes a processor. The “processor” is, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), a programmable logic device (for example, SPLD (Simple Programmable L). , A circuit such as a field programmable gate array (FPGA). For example, the control unit 10 can realize the functions according to the embodiment by reading and executing a program stored in a storage circuit or a storage device (such as the storage unit 20 or an external device).

  The control unit 10 may include a communication device for transmitting and receiving data via a communication line such as a local area network (LAN), the Internet, and a dedicated line.

<Collection control unit 11>
The control unit 10 includes a collection control unit 11. The collection control unit 11 controls the data collection unit 30. For example, the collection control unit 11 uses OCT such as light source control, optical scanner control, change in optical path length of measurement light and / or reference light, polarization adjustment, light amount adjustment, focus adjustment, fixation position change, and the like. Control various elements for collecting data. Some examples of processing that can be executed by the collection control unit 11 will be described later.

<Display control unit 12>
The control unit 10 includes a display control unit 12. The display control unit 12 executes control for displaying information on the display device 2. The display control unit 12 can execute display control based on the information stored in the storage unit 20.

  The display control unit 12 can perform processing (generation, processing, synthesis, etc.) regarding information displayed on the display device 2. For example, the display control unit 12 displays the evaluation result distribution (or information obtained therefrom), the blood vessel angle distribution (or information obtained therefrom), and the like on the image (front image) obtained by the front image obtaining unit 60. It can be displayed overlaid. Further, the display control unit 12 generates a composite image of the evaluation result distribution (or information obtained therefrom) and the front image, and a composite image of the blood vessel angle distribution (or information obtained therefrom) and the front image. Can do.

  Such processing may be executed by, for example, linking the display control unit 12 and other elements (other elements of the control unit 10, the data processing unit 40, etc.).

<Storage unit 20>
Various information is stored in the storage unit 20. In this example, the condition information 21 is stored in advance. The condition information 21 may be stored in an external device.

<Condition information 21>
The condition information 21 includes one or more conditions related to the inclination angle of the blood vessel, and is referred to by a measurement position setting unit 43 (evaluation processing unit 431) described later. Several examples of conditions included in the condition information 21 will be described.

  The first example of the condition is angle condition information for OCT blood flow measurement. Since OCT blood flow measurement uses a Doppler OCT signal, a good signal cannot be obtained unless the angle between the measurement light projection direction (A scan direction) and the blood flow direction is appropriate. The blood flow direction is considered to be substantially the same as the direction of the blood vessel at the measurement light projection position. Therefore, in OCT blood flow measurement, it is important to evaluate the inclination angle of the blood vessel with respect to the A scan direction.

  The angle condition information includes one or more conditions for evaluating the inclination angle of the blood vessel with respect to the A scan direction. The condition may include a tilt angle threshold and / or range. Further, the angle condition information may include conditions regarding the eye to be examined and conditions regarding the relationship between the eye to be examined and the ophthalmologic photographing apparatus 1. An example of the condition relating to the eye to be examined is the pupil diameter. As an example of the condition regarding the relationship between the eye to be examined and the ophthalmologic photographing apparatus 1, there is a relative position between the eye to be examined and the optical system of the ophthalmic photographing apparatus 1 (for example, displacement between the axis of the eye to be examined and the axis of the optical system).

  An example of the angle condition information is shown in FIG. The angle condition information 21 a is included in the condition information 21. The angle condition information 21a is table information including an evaluation field and an angle condition field, for example. In the evaluation column, “H”, “M”, and “N” are given as evaluation ranks. In the angle condition column, as conditions relating to the inclination angle of the blood vessel, an angle condition corresponding to H rank “75 to 80 degrees”, an angle condition corresponding to M rank “can be corrected to 75 to 80 degrees”, N rank The corresponding angle condition “cannot be corrected to 75-80 degrees” is given.

  The rank of evaluation represents the rank of suitability for OCT blood flow measurement. For example, the H rank represents aptitude “high”, the M rank represents aptitude “medium”, and the N rank represents aptitude “none”.

  The angle condition corresponding to the H rank represents a blood vessel inclination angle (an angle with respect to the A scan direction) that is highly suitable for OCT blood flow measurement. In this example, an angular condition “75 to 80 degrees” obtained experimentally or clinically, for example, is assigned to the H rank.

  The angle condition corresponding to the M rank represents a blood vessel inclination angle suitable for a medium level for OCT blood flow measurement. In this example, a condition that a suitable angle condition “75 to 80 degrees” can be realized by a predetermined correction process is assigned to the M rank. The correction process will be described later.

  The angle condition corresponding to the N rank represents a blood vessel inclination angle that is not suitable for OCT blood flow measurement. In this example, a condition that a suitable angle condition “75 to 80 degrees” cannot be realized even by a predetermined correction process is assigned to the N rank.

  A correction process used for determining the M rank and the N rank will be described. The correction process includes, for example, a shift of the measurement light path with respect to the axis of the eye to be examined (change in relative position). The amount of this shift is limited to the pupil diameter. The pupil diameter may be a measured value of the eye to be examined or a standard value (such as a statistical value). Alternatively, the pupil diameter after administration of the mydriatic agent or the estimated pupil diameter by administration of the mydriatic agent may be used.

  In the exemplary correction processing, when the evaluation processing unit 431 shifts the path of the measurement light with respect to the axis of the eye to be examined with the pupil diameter as a constraint, a suitable angle condition “75 to 80 degrees” is realized. It is determined whether or not. The relationship between the shift of the measurement light path with respect to the axis of the eye to be examined and the change in the measurement light projection direction (A scan direction) will be described below. As described above, since the inclination angle of the blood vessel is defined with reference to the A-scan direction, the change in the A-scan direction is equivalent to the change in the inclination angle of the blood vessel.

  Please refer to FIG. Each of the symbols LS0 and LS1 indicates a path of the measurement light (measurement path). Outside the eye E, the measurement paths LS0 and LS1 are parallel to each other and are separated by a distance d in a direction perpendicular to them. That is, the measurement path LS1 is a path shifted by the distance d with respect to the measurement path LS0. The length of the measurement optical path LS0 in the eye E is T.

  At this time, an angle Δθ formed by the measurement path LS0 and the measurement path LS1 at the fundus is calculated by the following equation: Δθ = arctan (d / T). Further, the sign of the angle Δθ, that is, the sign (+/−) of the correction amount of the blood vessel inclination angle is determined according to the shift direction of the measurement path LS1 with respect to the measurement path LS0. When the shift direction is along the length direction of the blood vessel (more generally, when the vector representing the shift includes a component in the length direction of the blood vessel or when the component is sufficiently large), the correction of the blood vessel inclination angle is performed. On the other hand, when the shift direction does not follow the length direction of the blood vessel (more generally, when the vector representing the shift does not include a component in the length direction of the blood vessel or when the component is sufficiently small), correction of the blood vessel inclination angle Is not done.

  A second example of conditions will be described. The second example is local angle distribution information for diagnosing the eye to be examined. Diseases to be diagnosed include diseases that cause (characteristic) deformation of blood vessels. The local angle distribution information includes the local distribution of the blood vessel inclination angle corresponding to the characteristic deformation of the blood vessel. As a typical example, a fundus blood vessel may protrude in the corneal direction or the opposite direction due to a tumor, fluid leakage, or the like. This protrusion is expressed as, for example, a local distribution in which a section in which the inclination angle with respect to the A-scan direction gradually decreases and a section in which the inclination angle gradually increases are adjacent to each other across a position with an inclination angle of 90 degrees. . The local angular distribution information includes at least one such characteristic local distribution.

  Local angle distribution information can be used for OCT blood flow measurement. For example, in the evaluation using the angle condition information 21a or the like, a position satisfying the condition represented by the local angle distribution information is selected as a target position for OCT blood flow measurement, or the condition represented by the local angle distribution information is satisfied. The position can be excluded from the target position for OCT blood flow measurement.

  A third example of conditions will be described. The third example is time-dependent angle change information for diagnosing the eye to be examined. The local angle distribution information of the second example represents the shape of the blood vessel (at a certain point in time). On the other hand, the time-dependent angle change information of the third example represents a change in the shape of the blood vessel over time. As a typical example, blood vessel deformation (the above-mentioned protrusion) increases with the progress of tumor and fluid leakage. Such changes in protrusion include, for example, changes in the width of a gradually decreasing section of the inclination angle, changes in the width of a gradually increasing section, changes in the height difference in a gradually decreasing section, and changes in the height difference in a gradually increasing section. And a change in slope in a gradually decreasing section, a change in slope in a gradually increasing section, and the like. The temporal angle change information includes at least one such characteristic change.

  The temporal angle change information can be used for OCT blood flow measurement. For example, in the evaluation using the angle condition information 21a or the like, a position satisfying the condition represented by the temporal angle change information is selected as a target position for OCT blood flow measurement, or the condition represented by the temporal angle change information is satisfied. The position can be excluded from the target position for OCT blood flow measurement.

<Data collection unit 30>
The data collection unit 30 collects a three-dimensional data set by performing OCT on the eye to be examined. The data collection unit 30 includes a configuration for performing measurement using, for example, a spectral domain OCT or a swept source OCT. This configuration includes an optical system, a drive system, a data acquisition system (DAQ), a control system, and the like, as in the past. This optical system includes, for example, an interference optical system, an optical scanner, and a photodetector. The interference optical system divides the light output from the light source into measurement light and reference light, projects the measurement light onto the subject's eye, and superimposes the return light of the measurement light from the subject's eye on the reference light to cause interference light. Is generated. The optical scanner includes a galvano scanner and the like, and deflects measurement light. The photodetector detects (the spectrum of) interference light generated by the interference optical system.

  In OCT angiography, the data collection unit 30 scans a three-dimensional region of the eye to be examined. The scan mode at that time is, for example, raster scan (three-dimensional scan). The raster scan is executed, for example, so as to scan each of the plurality of B cross sections a predetermined number of times, that is, sequentially scan the plurality of B cross sections a predetermined number of times. The three-dimensional data set collected by the data collection unit 30 is sent to the data processing unit 40.

  In OCT blood flow measurement, the data collection unit 30 repeatedly scans a cross section of interest that intersects the blood vessel of interest. The scan mode at that time is, for example, a line scan (B scan). This line scan is repeatedly executed at a predetermined frequency, for example. Data collected by the data collection unit 30 in each line scan is sent to the data processing unit 40.

  In the OCT blood flow measurement, the data collection unit 30 can further perform a scan for obtaining the inclination angle of the blood vessel of interest in the cross section of interest. This scan is performed on, for example, two cross sections intersecting the target blood vessel. Here, two cross sections can be arranged in the vicinity of the target cross section. Alternatively, one of the two cross sections may be disposed in the vicinity of the cross section of interest while the other is the cross section of interest. In this case, it is possible to use the data obtained by repeated scanning of the target section described above. In other words, the scan executed in the OCT blood flow measurement may be a combination of a repetitive scan of the cross section of interest and a scan of the other two cross sections, or a repetitive scan of the cross section of interest and a scan of the other cross section.

  The mode of scanning for obtaining the inclination angle of the blood vessel of interest in the cross section of interest is not limited to these. For example, three or more cross sections can be scanned. Alternatively, it is possible to scan a three-dimensional region including the target cross section (three-dimensional scan). As another example, a cross section that intersects the cross section of interest and is along the blood vessel of interest can be scanned.

<Data processing unit 40>
The data processing unit 40 performs various data processing. For example, the data processing unit 40 performs image processing and analysis processing on the image data of the eye to be examined. As a typical example, the data processing unit 40 performs rendering such as three-dimensional computer graphics (3DCG). The data processing unit 40 includes an image forming unit 41, a blood vessel angle distribution acquisition unit 42, a measurement position setting unit 43, and a blood flow information generation unit 44.

<Image forming unit 41>
The image forming unit 41 forms an OCT image based on the data set collected by the data collecting unit 30. For example, the image forming unit 41 forms a plurality of cross-sectional images (B-scan images) for each B cross-section based on the three-dimensional data set collected by the data collecting unit 30. The image forming process includes, for example, noise removal (noise reduction), filter processing, FFT (Fast Fourier Transform), and the like, as in the conventional OCT technology.

  The image forming unit 41 can form stack data by embedding these cross-sectional images in a single three-dimensional coordinate system. In this stack data, a predetermined number of cross-sectional images are assigned to each B cross-section. Further, the image forming unit 41 can form volume data (voxel data) by performing interpolation processing or the like on the stack data. Also for this volume data, a predetermined number of voxel groups are assigned to positions corresponding to the respective B cross sections. Stack data and volume data are examples of three-dimensional data sets.

  The image forming unit 41 performs various types of rendering on the three-dimensional data set, so that a B-mode image (longitudinal cross-sectional image, axial cross-sectional image), C-mode image (transverse cross-sectional image, horizontal cross-sectional image), projection image, shadow Gram etc. can be formed. An image of an arbitrary cross section such as a B mode image or a C mode image is formed by selecting pixels (pixels, voxels) on a specified cross section from a three-dimensional data set. The projection image is formed by projecting the three-dimensional data set in a predetermined direction (Z direction, depth direction, A scan direction). The shadowgram is formed by projecting a part of a three-dimensional data set (for example, partial data corresponding to a specific layer) in a predetermined direction. An image such as a C-mode image, a projection image, or a shadowgram with the viewpoint of the front side of the eye to be examined is called a front image.

  The image forming unit 41 can execute various image processes in addition to rendering. For example, there are segmentation for obtaining a specific tissue and tissue boundary, and size analysis for obtaining the size (layer thickness, volume, etc.) of the tissue. When a specific layer (or a specific layer boundary) is obtained by segmentation, it is possible to reconstruct a B-mode image or a front image so that the specific layer becomes flat. Such an image is called a flattened image.

  The image forming unit 41 can form a blood vessel emphasized image (angiogram). A blood vessel enhancement image is an image in which an image region (blood vessel region) corresponding to a blood vessel is identified by analyzing OCT data, and the expression mode of the blood vessel region is changed to enhance it. A plurality of OCT data obtained by repeatedly scanning substantially the same range of the eye to be examined is used for specifying the blood vessel region. In the embodiment, a three-dimensional data set is used to display a blood vessel emphasized image as a planar image.

  The blood vessel emphasized image represents, for example, a blood vessel distribution (that is, a three-dimensional distribution of blood vessels) in a three-dimensional region of the fundus subjected to OCT scanning. There are several types of techniques for forming a blood vessel enhanced image. A typical technique for this will be described. In this process, a three-dimensional data set including a plurality of B-mode images arranged in time series for each B section by repeatedly scanning each of the plurality of B sections of the eye to be examined is used. Note that there are fixation and tracking as a method for repeatedly scanning substantially the same B section.

  In the process of forming a blood vessel emphasized image, first, alignment of a plurality of B mode images is executed for each B cross section. This alignment is performed using, for example, a known image matching technique. As a typical example, it is possible to execute extraction of feature regions in each B-mode image and alignment of a plurality of B-mode images by alignment of the extracted plurality of feature regions.

  Subsequently, a process of specifying an image region changing between the plurality of aligned B-mode images is performed. This process includes, for example, a process for obtaining a difference between different B-mode images. Each B-mode image is luminance image data representing the form of the eye to be examined, and an image region corresponding to a part other than a blood vessel is considered to be substantially unchanged. On the other hand, considering that the backscattering contributing to the interference signal changes randomly due to blood flow, an image region in which a change occurs between a plurality of aligned B-mode images (for example, a pixel whose difference is not zero, or It is possible to estimate that a pixel whose difference is equal to or greater than a predetermined threshold is a blood vessel region.

  Information indicating that it is a blood vessel region is assigned to the image region thus identified. By executing the above process on a plurality of B cross sections, a three-dimensionally distributed blood vessel region is obtained. By rendering such a three-dimensional blood vessel enhancement image, a front image representing a blood vessel distribution, an image of an arbitrary cross section, a shadowgram of an arbitrary range, and the like are generated.

  The process for forming the blood vessel emphasized image is not limited to this. For example, the blood vessel region can be specified by a conventional method using Doppler OCT, or the blood vessel region can be specified by using a conventional image processing method. Moreover, it is possible to identify a blood vessel region for each part by using different methods depending on the part. For example, the blood vessel region can be specified using the above-described typical method or Doppler OCT method for the retina, and the blood vessel region can be specified using the image processing method for the choroid.

<Blood angle distribution acquisition unit 42>
The blood vessel angle distribution acquisition unit 42 obtains a blood vessel angle distribution based on the three-dimensional blood vessel enhancement image formed by the image forming unit 41. This blood vessel angle distribution represents the inclination angle of the blood vessel at one or more positions of the fundus, and typically represents the inclination angle of the blood vessel at two or more positions. An example of how to determine the inclination angle of the blood vessel will be described below. The position at which the tilt angle is obtained may be, for example, an A scan position in a three-dimensional data set, or may be a position between two adjacent A scan positions.

  In the first example, the blood vessel angle distribution acquisition unit 42 creates a blood vessel axis model by thinning the blood vessel region in the three-dimensional blood vessel emphasized image. This process can be performed using a known thinning algorithm.

  The blood vessel angle distribution acquisition unit 42 can obtain the blood vessel inclination angle at the target position by calculating the inclination at an arbitrary position (target position) of the blood vessel axis model. When the blood vessel axis model is differentiable at the position of interest, the blood vessel angle distribution acquisition unit 42 can calculate the inclination by differentiation. On the other hand, when the vascular axis model cannot be differentiated at the position of interest, for example, based on the position of the vascular axis line at the position of interest and the position of the blood vessel axis at the vicinity position (one or more neighboring positions). The inclination (approximate value) at the position can be calculated.

  A second example will be described. Please refer to FIG. Symbol B0 indicates a tomographic image (target tomographic image) representing a cross section (target cross section) including the target position where the blood vessel tilt angle is calculated. A blood vessel region V0 is depicted in the tomographic image B0 of interest. Reference numerals B11 and B12 indicate two tomographic images (neighboring tomographic images) representing two cross sections (neighboring cross sections) located in the vicinity of the target cross section B0. In the nearby tomographic image B11, a blood vessel region V11 in another cross section of the same blood vessel (target blood vessel) as the blood vessel region V0 is depicted. Similarly, in the nearby tomographic image B12, a blood vessel region V12 in another cross section of the target blood vessel is depicted.

  Here, for example, by applying a known process such as labeling or region growing to the three-dimensional blood vessel enhancement image, it is possible to grasp the position (distribution) of the target blood vessel and set a neighboring cross section. It is also possible to provide a display and a graphical user interface (GUI) for the user to set at least one of the attention cross section and the neighboring cross section.

  The blood vessel angle distribution acquisition unit 42 calculates the inclination of the blood vessel of interest in the cross section of interest based on the tomographic image B0 and the neighboring tomographic images B11 and B12. Note that the number of neighboring tomographic images to be referred to is not limited to two and may be one or more arbitrary numbers.

  The blood vessel angle distribution acquisition unit 42 calculates the inclination of the blood vessel of interest in the cross section of interest based on the blood vessel regions V0, V11, and V12 and the distance between cross sections. The distance between cross sections may include a distance between the nearby tomographic image B11 and the nearby tomographic image B12. The cross-sectional distance may include at least one of the distance between the nearby tomographic image B11 and the target tomographic image B0 and the distance between the nearby tomographic image B12 and the target tomographic image B0. Let L be the interval between the nearby tomographic image B11 (B12) and the target tomographic image B0.

  The A scan direction shown in FIG. 4 (the direction indicated by the arrow pointing downward) is, for example, located at the center of the A scan image included in the target tomographic image B0 (for example, the plurality of A scan images included in the target tomographic image B0). (A scan image) direction. In this example, the angle formed by the A scan direction in the cross section of interest and the direction A of the blood vessel of interest can be defined as the inclination angle of the blood vessel of interest in the cross section of interest.

  In one example, the blood vessel angle distribution acquisition unit 42 can calculate the direction A of the target blood vessel in the target cross section based on the positional relationship between the three blood vessel regions V0, V11, and V12. This positional relationship is obtained, for example, by connecting three blood vessel regions V0, V11, and V12. Specifically, the blood vessel angle distribution acquisition unit 42 specifies the feature points of the three blood vessel regions V0, V11, and V12 and connects these feature points. As the feature points, there are a center position (axis position), a gravity center position, an uppermost portion, and the like. In addition, as a method of connecting these feature points, there are a method of connecting with line segments, a method of connecting with approximate curves (spline curve, Bezier curve, etc.), and the like.

  Further, the blood vessel angle distribution acquisition unit 42 calculates the direction A based on a line connecting these feature points. When a line segment is used, the blood vessel angle distribution acquisition unit 42, for example, a first line segment that connects a feature point of the blood vessel region V0 in the target tomographic image B0 and a feature point of the blood vessel region V11 in the neighboring tomographic image B11. The direction A can be calculated based on the inclination and the inclination of the second line segment connecting the feature point of the blood vessel region V0 and the feature point of the blood vessel region V12 in the nearby tomographic image B12. As an example of this calculation process, the average value of the slopes of two line segments can be obtained. Further, as an example of connecting with an approximate curve, the slope of the approximate curve at the intersection position of the approximate curve and the target cross section can be obtained.

  In this example, the blood vessel regions in three cross sections are considered, but the inclination can be obtained in consideration of the blood vessel regions in the two cross sections. As a specific example, the direction A of the target blood vessel in the target cross section can be obtained based on the blood vessel region V11 in the nearby tomographic image B11 and the blood vessel region V12 in the nearby tomographic image B12. Further, the direction A of the target blood vessel in the target cross section can be obtained based on the blood vessel region V11 in the nearby tomographic image B11 and the blood vessel region V0 in the target tomographic image B0. For example, the inclination of the first line segment or the second line segment can be obtained and used as the orientation A of the target blood vessel.

  In the above example, only one blood vessel direction is obtained and used as the direction A. However, 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 direction A.

<Measurement position setting unit 43>
The measurement position setting unit 43 sets a measurement position to be subjected to OCT blood flow measurement based on the blood vessel angle distribution acquired by the blood vessel angle distribution acquisition unit 42. The blood vessel angle distribution represents the inclination angle of the blood vessel at one or more positions of the fundus, and typically represents the inclination angle of the blood vessel at two or more positions. The tilt angle is defined with reference to the A scan direction (incidence direction of OCT measurement light) at the position, for example.

  The measurement position setting unit 43 has, for example, a function for evaluating whether or not the inclination angle is suitable for OCT blood flow measurement for at least part of the inclination angle represented in the blood vessel angle distribution, and / or A function of evaluating how suitable the inclination angle is in OCT blood flow measurement may be provided. As an example of a configuration for performing such evaluation, an evaluation processing unit 431 can be provided.

<Evaluation processing unit 431>
The evaluation processing unit 431 evaluates suitability as a target position for OCT blood flow measurement based on the inclination angle included in the blood vessel angle distribution. More generally, the evaluation processing unit 431 can determine whether the inclination angle acquired by the blood vessel angle distribution acquisition unit 42 satisfies a predetermined condition. In addition, the evaluation processing unit 431 can specify one or more positions of the fundus satisfying a predetermined condition among a plurality of positions in the blood vessel angle distribution. The predetermined condition is included in the condition information 21.

  When the angle condition information is applied, the evaluation processing unit 431 compares the inclination angle represented in the blood vessel angle distribution with the angle condition information, so that the inclination angle (the fundus position corresponding thereto) is determined as OCT blood. It can be evaluated whether it is suitable for flow measurement. According to such processing, an evaluation rank can be assigned to at least a part of a plurality of positions included in the blood vessel angle distribution.

  For example, when the angle condition information 21a shown in FIG. 2 is applied, at least one of H rank, M rank, and N rank is assigned to the inclination angle (fundus position corresponding thereto) represented in the blood vessel angle distribution. It is done. Typically, the H rank position, the M rank position, and the N rank position can be specified. Moreover, only the position of the H rank that is highly suitable for OCT blood flow measurement can be assigned. In addition, only M rank positions that are moderately suitable for OCT blood flow measurement can be assigned. In addition, only N rank positions that are not suitable for OCT blood flow measurement can be assigned.

  When the local angle distribution information is used for evaluation, the evaluation processing unit 431 causes a characteristic deformation based on, for example, the blood vessel angle distribution acquired by the blood vessel angle distribution acquisition unit 42 and the local angle distribution information. It is possible to identify a portion of a blood vessel that is present (a portion where the blood vessel has a characteristic shape). As described above, the characteristic deformation is a protrusion due to, for example, a tumor or fluid leakage. It is also possible to detect blood meandering, local changes in blood vessel diameter, and the like as characteristic deformations. Further, the result of such processing can be used for evaluation of suitability for OCT blood flow measurement.

  When the temporal angle change information is used for the evaluation, the evaluation processing unit 431 determines whether the blood vessel shape changes over time based on the blood vessel angle distribution acquired by the blood vessel angle distribution acquisition unit 42 and the temporal angle change information, for example. A site that is characteristic can be identified. As described above, the characteristic temporal change of the blood vessel shape is caused by progression of, for example, a tumor or fluid leakage. It is also possible to detect changes over time in the meandering state of blood vessels and changes over time in the diameter of blood vessels as characteristic changes over time. Further, the result of such processing can be used for evaluation of suitability for OCT blood flow measurement.

  Here, when the measurement path shift (see FIG. 3) is applied, the accuracy of the comparison with the local angle distribution information and the temporal angle change information may be reduced due to the change in the incident angle of the measurement light with respect to the fundus. is there. For example, even when the same position of the fundus is targeted, the apparent inclination angle of the blood vessel changes depending on whether the measurement path is shifted or not, and the comparison result with the local angle distribution information also changes. Similarly, when detecting changes in blood vessels over time, it is not appropriate to compare the inclination angle obtained by shifting the measurement path with the inclination angle obtained without shifting.

  In view of such circumstances, for example, OCT angiography is performed again according to the shift of the measurement path, OCT measurement is performed while reproducing the same shift state as in the past, and the blood vessel angle distribution is determined according to the shift amount. It is possible to correct. The correction of the blood vessel angle distribution (measurement value of the tilt angle) according to the shift amount can be executed so as to cancel the angle Δθ shown in FIG. 3, for example.

  In addition, the presence or absence of the measurement path and the shift amount can be detected by using a known configuration for performing alignment (alignment) between the apparatus optical system and the eye to be examined. For example, the alignment state (presence / absence of shift, shift amount) is determined from the position of the feature point (pupil center, etc.) in the anterior segment image obtained by photographing the anterior segment of the subject's eye (by the front image acquisition unit 60). Can be detected. Alternatively, it is also possible to detect the reflected light of the light beam projected from the oblique direction with respect to the cornea to obtain the corneal apex position and to detect the alignment state therefrom.

  The evaluation result acquired by the evaluation processing unit 431 is used for setting a position (measurement position) where OCT blood flow measurement is performed. For example, the measurement position setting unit 43 can set one or more positions determined as to whether the inclination angle satisfies a predetermined condition as the measurement position.

  When the angle condition information 21a shown in FIG. 2 is applied, for example, one or more positions determined as H rank are set as measurement positions. At this time, it is possible to select a position (one or two or more) by ranking one or more positions determined to be H ranks. This ranking can be performed based on, for example, the value of the inclination angle at each position, or can be performed based on other information. Examples of other information include an evaluation result based on local angle distribution information, an evaluation result based on temporal angle change information, a blood vessel thickness, a blood vessel depth position, a positional relationship with a nearby blood vessel, a blood vessel type ( Artery, vein, etc.), branching state of blood vessel, positional relationship with a lesion, diagnosis name (definite diagnosis name, suspect diagnosis name, etc.), past measurement position, and the like. These pieces of information can be referred to in other processes.

  When there is no position determined as H rank, for example, a measurement site can be set from among positions determined as M rank. Alternatively, when there is no position determined as H rank, or when there is no position determined as H rank or part determined as M rank, OCT angiography and acquisition of blood vessel angle distribution may be performed again, Can be urged to be performed again.

<Blood flow information generation unit 44>
The blood flow information generation unit 44 operates for OCT blood flow measurement. The blood flow information generation unit 44 generates blood flow information representing a blood flow state in the blood vessel based on the data collected by the data collection unit 30 for OCT blood flow measurement and the inclination angle of the blood vessel.

  The data collected by the data collection unit 30 includes at least data (first data) collected by repeatedly scanning a cross section of interest that intersects the blood vessel of interest, crosses the blood vessel of interest, and is different from the cross section of interest 1 Data (second data) obtained by scanning the above cross section (cross section in the vicinity of the target cross section) may be further included. When the second data is not included, for example, the inclination angle of the blood vessel of interest at the position of the cross section of interest or a position near the cross section obtained separately from the OCT blood flow measurement can be used. As an example, the inclination angle (blood vessel angle distribution) obtained by the blood vessel angle distribution acquisition unit 42 can be used.

  An example of processing executed by the blood flow information generation unit 44 will be described. In a typical example, the blood flow information generating unit 44 forms a fundus tomographic image and a phase image based on the data collected by the data collecting unit 30.

  In OCT blood flow measurement, two types of scanning (auxiliary scanning and main scanning) are performed on the fundus. The auxiliary scan is executed to scan one or more cross sections (cross sections in the vicinity of the target cross section) different from the target cross section and collect the second data. In a typical auxiliary scan, two or more cross sections intersecting the blood vessel of interest are scanned with measurement light. Data acquired by the auxiliary scanning is used to obtain the inclination angle of the target blood vessel in the target cross section. On the other hand, the main scan is executed to collect first data by repeatedly scanning a cross section of interest intersecting the blood vessel of interest with measurement light. The section on which the auxiliary scanning is performed is arranged in the vicinity of the target section. The main scanning is Doppler measurement using OCT.

  For example, the target cross section of the auxiliary scan and the main scan is oriented so as to be orthogonal to the traveling direction of the blood vessel of interest. In addition, the distance between the target cross section of the auxiliary scan and the target cross section (inter-section distance) is set in advance or set for each examination. As an example of the latter, it is possible to set the distance between cross sections based on a predetermined factor such as the curvature of the blood vessel of interest at or near the cross section of interest and the inspection accuracy. Further, the user may set a desired cross-sectional distance.

  This scan is 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 execution time of the main scan may be a predetermined time set in advance, or may be a time set for each patient or for each examination.

  The blood flow information generation unit 44, for example, based on data collected by auxiliary scanning on two auxiliary cross sections set in the vicinity of the target cross section, a tomographic image representing the form of the first auxiliary cross section, 2 A tomographic image representing the shape of the auxiliary cross section is formed. At this time, it is possible to improve the image quality by using a technique such as addition averaging, or to select an optimal one from two or more tomographic images of each auxiliary section.

  Furthermore, the blood flow information generation unit 44 forms a tomographic image group representing a time-series change in the form of the cross section of interest based on the data collected by the main scan (repetitive scan) with respect to the cross section of interest. This process is realized, for example, by forming a tomographic image from data collected for each repetition of scanning. Alternatively, the image quality may be improved by forming two or more tomographic images from two or more data collected for each predetermined number of repetitions and obtaining an average of these (addition average, moving average, etc.).

  The processing executed by the blood flow information generation unit 44 includes, for example, noise removal (noise reduction), filter processing, FFT (Fast Fourier Transform), and the like, as in the conventional OCT technology. Note that the tomographic image forming process described here is the same as the process executed by the image forming unit 41. Therefore, the tomographic image forming process can be performed by the image forming unit 41.

  The blood flow information generation unit 44 forms a phase image representing a time-series change of the phase difference in the cross section of interest based on the data collected by the main scan for the cross section of interest. The data used for this processing is the same as the data used to form the tomographic image (group) of the cross section of interest. Therefore, there is a natural positional correspondence between the tomographic image of the cross section of interest and the phase image, and registration is easy.

  An example of a phase image forming method will be described. In a typical example, a phase image is obtained by calculating a phase difference between adjacent A-line complex signals (signals corresponding to adjacent scanning points). In other words, the phase image in this example is formed based on the time-series change of the pixel value (luminance value) of each pixel of the tomographic image of the cross section of interest. For an arbitrary pixel, the blood flow information generation unit 44 considers a graph of a time-series change in luminance value. The blood flow information generation unit 44 obtains a phase difference Δφ between two time points t1 and t2 (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, a time-series change in 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, a color indicating that the phase has increased along the time series (for example, red) can be different from a color indicating that the phase has decreased (for example, blue). 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 presented in color and density. A phase image is formed by executing the above processing for each pixel.

  The time-series change of the phase difference is obtained by ensuring the phase correlation by sufficiently reducing the time interval Δt. 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 is executed.

  The blood flow information generation unit 44 can execute, for example, a blood vessel region specifying process, an inclination angle calculation process, and a blood flow information generation process. The blood flow information generation process may include, for example, a blood flow velocity calculation process, a blood vessel diameter calculation process, and a blood flow volume calculation process.

  In the blood vessel region specifying process, the blood flow information generating unit 44 specifies a blood vessel region in the tomographic image corresponding to the blood vessel of interest. Furthermore, the blood flow information generation unit 44 specifies a blood vessel region in the phase image corresponding to the blood vessel of interest. The blood vessel region is specified by analyzing the pixel value of each image (for example, threshold processing). The blood vessel region in the phase image may be specified based on the blood vessel region in the tomographic image and the registration result of the tomographic image and the phase image.

  In the tilt angle calculation process, the blood flow information generation unit 44 calculates the tilt angle of the target blood vessel in the target cross section based on the data acquired by the auxiliary scanning. For example, the blood flow information generation unit 44 can calculate the inclination angle of the blood vessel of interest in the cross section of interest based on the distance between cross sections and the result of specifying the blood vessel region. This process is the same as the process (see FIG. 4) executed by the blood vessel angle distribution acquisition unit 42. In addition, when using the inclination angle acquired by the blood vessel angle distribution acquisition part 42 for OCT blood flow measurement, it is not necessary to perform an inclination angle calculation process.

  In the blood flow information generation process, the blood flow information generation unit 44 uses the data (phase image) acquired by the main scanning (Doppler OCT) and the blood vessel inclination angle (or blood vessel angle distribution) calculated by the inclination angle calculation process. Blood flow information related to the target blood vessel is generated on the basis of the inclination angle obtained by the acquisition unit 42). As described above, a typical example of blood flow information generation processing includes blood flow velocity calculation processing, blood vessel diameter calculation processing, and blood flow volume calculation processing.

  The blood flow information generation unit 44 can calculate the blood flow velocity in the target cross section of the blood flowing in the target blood vessel based on the time-series change of the phase difference obtained as the phase image. The value calculated by this processing may be a blood flow velocity at a certain point in time, or a time-series change in blood flow velocity (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 of the electrocardiogram (for example, the time phase of the R wave). In addition, the time range in the latter is the entire time or arbitrary part of the time when the cross section of interest is scanned.

  When the blood flow velocity change information is obtained, the blood flow information generation unit 44 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 information generation unit 44 can calculate the blood flow velocity using the Doppler OCT method as described above. For example, the following relational expression is used for calculating the blood flow velocity.

Δf: Doppler shift received by scattered light of measurement light n: Refractive index of medium (blood) v: Flow velocity of medium (blood flow velocity)
θ: Angle (inclination angle) formed by the incident direction of the measurement light and the direction of flow of the medium
λ: Center wavelength of measurement light

  In a typical example, the refractive power n of the medium and the center wavelength λ of the measurement light are known, the Doppler shift Δf is obtained from the time-series change of the phase difference, and the inclination angle θ is the inclination angle calculation process or blood vessel angle distribution. Obtained from. The blood flow information generation unit 44 can calculate the blood flow velocity v by substituting these values into the relational expression.

  In the blood vessel diameter calculation process, the blood flow information generation unit 44 calculates the diameter of the target blood vessel in the target cross section. As an example of this calculation method, there are a first calculation method using a front image of the fundus and a second calculation method using a tomographic image.

  When the first calculation method is applied, the fundus region including the position of the cross section of interest is imaged in advance. This fundus photographing is performed by the front image acquisition unit 60, for example. Alternatively, a front image of the fundus acquired and saved in the past may be read.

  The blood flow information generation unit 44 is based on various factors that determine 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 in the front image. This scale represents the length in real space. As a specific example, this scale associates 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, a scale corresponding to the factor is selectively applied.

  The blood flow information generation unit 44 calculates the diameter of the blood vessel of interest in the cross section of interest, that is, the diameter of the blood vessel region, based on the scale and the pixels included in the blood vessel region. As a specific example, the blood flow information generation unit 44 can obtain a maximum value or an average value of diameters in various directions of the blood vessel region. Alternatively, the blood flow information generation unit 44 can approximate the outline of the blood vessel region in a circle or an ellipse and obtain the diameter of the circle or ellipse. Since the area of the blood vessel region can be (substantially) determined once the blood vessel diameter is determined, the area may be calculated instead of obtaining the blood vessel diameter.

  A second calculation method will be described. In the second calculation method, a tomographic image of the fundus at the cross section of interest is used. This tomographic image may be a tomographic image based on the main scanning, or may be obtained separately. The scale in this tomographic image is determined according to the scanning mode of the measurement light. The length of the cross section of interest 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 flow information generation unit 44 can obtain an interval between adjacent pixels based on the length of the cross section of interest, and can calculate the diameter of the blood vessel of interest in the cross section of interest in the same manner as the first calculation method.

  In the blood flow calculation process, the blood flow information generation unit 44 calculates the flow rate of blood flowing in the target blood vessel 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, the blood vessel diameter is set as w, and the maximum blood flow velocity is set as Vm. In this case, the blood flow rate Q is expressed by the following relational expression.

  The blood flow information generation unit 44 substitutes the blood vessel diameter w obtained by the blood vessel diameter calculation processing and the maximum value Vm in the blood flow velocity obtained by the blood flow velocity calculation processing into the above relational expression. Q can be calculated.

<Operation unit 50>
The operation unit 50 is used for a user to input an instruction to the ophthalmologic photographing apparatus 1. The operation unit 50 may include a known operation device used for an ophthalmologic apparatus or a computer. For example, the operation unit 50 may include a mouse, a touch pad, a trackball, a keyboard, a pen tablet, an operation panel, a joystick, a button, a switch, and the like. The operation unit 50 may include a touch panel. In this case, the control unit 10 can display a GUI for operating the ophthalmologic photographing apparatus 1 on the touch panel.

<Front image acquisition unit 60>
The front image acquisition unit 60 acquires a front image of the fundus. The process for acquiring the front image is arbitrary. In the first example, the front image acquisition unit 60 may include a configuration for photographing the fundus. For example, the front image acquisition unit 60 may include a fundus camera optical system, an SLO optical system, and the like.

  In the second example, the front image acquisition unit 60 may include a configuration for acquiring a front image of the fundus of the subject eye from an external device. For example, the front image acquisition unit 60 may include a communication device for transmitting and receiving data via a communication line such as a LAN, the Internet, or a dedicated line. In this case, the front image acquisition unit 60 can acquire a front image of the fundus of the eye to be examined stored in, for example, an electronic medical record system or an image archiving system, using a patient ID, a DICOM tag, or the like as a search query.

  In the third example, the front image acquisition unit 60 may include a processor that forms a front image by OCT. Examples of the OCT front image include a C-mode image, a projection image, and a shadowgram.

  When the front image is formed by rendering the three-dimensional data set used to form the blood vessel emphasized image, the blood vessel emphasized image and the front image are transmitted via a common three-dimensional data set (that is, a common three-dimensional coordinate system) Can be registered. In general, registration between a blood vessel-enhanced image and a front image includes, for example, processing for detecting a characteristic part (optic nerve head, macular part, blood vessel, lesion, laser scar, etc.) from both images, and both characteristic parts. Can be performed through the process of aligning both images with reference to.

<Operation>
Several examples of operations that can be performed by the exemplary ophthalmic imaging apparatus will be described.

<First operation example>
In the first operation example, OCT blood flow measurement is performed at a measurement position set based on a blood vessel angle distribution obtained using OCT angiography. FIG. 5 shows a flow of processing executed in this example. Preliminary processing such as input of patient ID, alignment of the optical system with respect to the subject's eye, focus adjustment of the optical system, OCT optical path length adjustment, fixation position adjustment, OCT scan range setting, etc. has already been performed. (The same applies to other operation examples and other embodiments).

(S1: Collect 3D data set by fundus OCT)
For OCT angiography, the data collection unit 30 collects a three-dimensional data set of the fundus of the subject's eye using OCT under the control of the collection control unit 11. The collected three-dimensional data set is sent to the data processing unit 40.

(S2: forming a blood vessel emphasized image of the fundus)
The image forming unit 41 forms a three-dimensional blood vessel emphasized image based on the three-dimensional data set collected in step S1.

(S3: Obtain blood vessel angle distribution)
The blood vessel angle distribution acquisition unit 42 obtains the blood vessel angle distribution based on the three-dimensional blood vessel enhancement image formed in step S2. The obtained blood vessel angle distribution is stored in the storage unit 20, for example.

(S4: Set the measurement position)
The measurement position setting unit 43 sets a measurement position based on the blood vessel angle distribution obtained in step S3. At this time, for example, the evaluation processing unit 431 evaluates the suitability of the one or more positions of the fundus as the target site for OCT blood flow measurement based on the blood vessel angle distribution obtained in step S3. The measurement position setting unit 43 can set the measurement position using the result of the evaluation.

(S5: Perform OCT blood flow measurement)
The ophthalmologic imaging apparatus 1 performs OCT blood flow measurement at the measurement position set in step S4.

  At this time, the collection control unit 11 controls a light source and an optical scanner included in the data collection unit 30. Under the control of the collection control unit 11, the data collection unit 30 collects the first data by executing at least the first cross-sectional scan intersecting the blood vessel at the measurement position set in step S4. In addition, the data collection unit 30 can collect the second data by scanning one or more auxiliary cross sections that intersect the blood vessel.

  The blood flow information generation unit 44 generates blood flow information related to the blood vessel based on the first data collected by the data collection unit 30 and the inclination angle of the blood vessel in the first cross section. When the second data is collected, the blood flow information generation unit 44 obtains the inclination angle of the blood vessel in the first cross section based on the second data. When the second data is not collected, for example, an inclination angle (an inclination angle at the measurement position, an inclination angle near the measurement position, etc.) represented in the blood vessel angle distribution is used.

  The control unit 10 can display the generated blood flow information on the display device 2, save it in the storage unit 20, and transmit it to an external device. Similarly, information obtained in OCT blood flow measurement (tomographic image, phase image, etc.) and / or image obtained in OCT angiography (three-dimensional data set, blood vessel enhancement image, etc.) are also displayed, Storage, transmission, etc. can be performed.

<Second operation example>
In the second operation example, an image representing the measurement position (measurement position image) is displayed on the fundus front image so as to be recognized by the user. The flow of processing executed in this example is shown in FIG.

(S11-S14)
Steps S11, S12, S13, and S14 are respectively performed in the same manner as steps S1, S2, S3, and S4 of the first operation example.

(S15: Acquire a front image of the fundus)
The front image acquisition unit 60 acquires a front image of the fundus. For example, the front image acquisition unit 60 captures the fundus after step S14. This fundus imaging is, for example, imaging using infrared light. Typically, the latest frame of an infrared observation image (moving image) that has been acquired at an arbitrary timing is used as the front image. The front image acquisition unit 60 can also acquire a front image of the fundus by accessing an electronic medical record system or the like, or by rendering the three-dimensional data set collected in step S11. The timing for performing the front image acquisition process may be arbitrary.

(S16: The position in the front image corresponding to the measurement position is specified)
The data processing unit 40 (and / or the display control unit 12 or the like) specifies a position corresponding to the measurement position set in step S14 in the front image acquired in step S15. This process can be executed as follows, for example.

  First, the data processing unit 40 creates a projection image of the three-dimensional data set acquired in step S11. This process includes an operation of integrating the pixels of the three-dimensional data set in the A scan direction (depth direction, depth direction). The projection image is a front image representing the form of the fundus.

  Next, the data processing unit 40 performs registration between the projection image and the front image acquired in step S15. Thereby, the position in the projection image is associated with the position in the front image.

  Here, the measurement position set in step S14 is set using a three-dimensional data set, and a projection image is also created from the three-dimensional data set. Therefore, the position in the front image corresponding to this measurement position can be specified through the three-dimensional coordinate system defined in the three-dimensional data set and the registration result.

  In addition, the process for specifying the position in the front image corresponding to the measurement image is not limited to this example. For example, a similar processing result can be obtained by performing registration between the blood vessel emphasized image formed in step S12 and the front image acquired in step S15.

(S17: The measurement position image is displayed superimposed on the front image)
The display control unit 12 displays the front image acquired in step S15 on the display device 2, and displays an image representing the position specified in step S16 (measurement position image) as an overlay display on the front image.

  The form of the measurement position image is arbitrary. For example, the measurement position image is an image having a predetermined shape, a predetermined size, and a predetermined color. The measurement position image may include an image indicating the position of the first cross section, for example. Further, the measurement position image may include an image indicating the position of the second cross section. Further, the measurement position image may include an image representing a region including the first cross section (and the second cross section). Further, the measurement position image may include an image showing a blood vessel (attention blood vessel) that is symmetrical with OCT blood flow measurement. The measurement position image is not limited to these. An example of the display mode of the front image and the measurement position image will be described later.

(S18: OCT blood flow measurement is performed)
The ophthalmologic imaging apparatus 1 performs OCT blood flow measurement at the measurement position set in step S14 (that is, the position indicated by the measurement position image displayed on the front image in step S17). OCT blood flow measurement is performed in the same manner as in step S5 of the first operation example.

  An example of the display mode in step S17 is shown in FIG. In this example, for example, a measurement position image indicating the position of the first cross section and a measurement position image indicating the position of the second cross section are displayed in an overlay on the front image G acquired by the fundus camera.

  The measurement position image indicating the position of the first cross section includes a linear image D1 that intersects the target blood vessel C. Further, the measurement position image indicating the position of the second cross section includes two linear images D2 and D3 that intersect the target blood vessel C in the vicinity of the linear image D1. The linear image D2 is located upstream (or downstream) of the blood vessel C of interest with respect to the linear image D1, and the linear image D3 is downstream (or upstream) of the blood vessel of interest with respect to the linear image D1. ).

  With these three linear images D1, D2 and D3, the user can grasp which blood vessel (attention blood vessel C) in the fundus is subjected to OCT blood flow measurement, and which of the attention blood vessels C Whether OCT blood flow measurement is performed at the position can be grasped.

  The three linear images D1, D2, and D3 may all be displayed in the same color, or may be displayed in two or more colors. For example, the linear image D1 indicating the position of the first cross section is displayed in a first color (for example, red), and the linear images D2 and D3 indicating the positions of two second cross sections are displayed in the second color (for example, blue). By doing so, it is possible to present the first cross section and the second cross section in an identifiable manner.

<Third operation example>
In the third operation example, an example of a measurement mode will be described. The measurement mode of this example is used when OCT blood flow measurement is performed on a blood vessel (attention blood vessel) designated by the user or the ophthalmologic imaging apparatus 1 (attention blood vessel mode). Other examples of the measurement mode will be described later. The flow of processing executed in this example is shown in FIG.

(S21: Designate the target blood vessel)
In this example, first, a target blood vessel is designated. The designation of the target blood vessel is executed manually or automatically.

  When manually specifying the target blood vessel, for example, the display control unit 12 displays a front image of the fundus of the eye to be examined on the display device 2. Typically, the display control unit 12 displays the front image acquired by the front image acquisition unit 60 by capturing the fundus or the front image acquired by accessing an electronic medical record system or the like on the display device 2. indicate. The user designates a desired blood vessel in the front image displayed on the display device 2 by using the operation unit 50. This designation operation is, for example, a click operation with a mouse or a touch operation with a finger. For example, the control unit 10 stores the front image and the position designated by the user (position information of the target blood vessel) in the storage unit 20.

  When the target blood vessel is automatically designated, for example, the control unit 10 accesses an electronic medical chart system or the like, and acquires information indicating a predetermined blood vessel in the fundus of the eye to be examined. As an example, the control unit 10 acquires information indicating a blood vessel in which OCT blood flow measurement has been performed in the past. In addition, when a blood vessel to be subjected to OCT blood flow measurement is determined according to a predetermined factor (diagnostic name, etc.), the control unit 10 accesses an electronic medical record system and obtains a diagnostic name, etc. of the eye to be examined. Then, the target blood vessel corresponding to the diagnosis name or the like is selected. The control unit 10 stores information indicating the automatically designated blood vessel in the storage unit 20.

  As another example of automatically specifying the target blood vessel, the data processing unit 40 can specify the target blood vessel by analyzing the fundus image (front image, OCT image, etc.) of the eye to be examined. This analysis process includes, for example, a process of comparing a blood vessel form (meandering, thickness, etc.) with a standard value. The control unit 10 stores information (and the image) indicating the target blood vessel designated by the data processing unit 40 in the storage unit 20.

(S22: A three-dimensional data set of a region including the blood vessel of interest is collected by fundus OCT)
The front image acquisition unit 60 acquires a front image by photographing the fundus of the eye to be examined. The data processing unit 40 or the like performs registration between the front image and the image (front image, OCT image, etc.) stored in the storage unit 20 in step S21, so that a region in the front image corresponding to the target blood vessel is obtained. Can be specified. If no image is stored in the storage unit 20 in step S21, for example, the data processing unit 40 or the like is placed in the anatomical form (direction, tissue arrangement, etc.) of the fundus or the position specified in step S21. Based on this, it is possible to specify a region in the front image corresponding to the blood vessel of interest.

  In order to perform OCT angiography of the region including the region in the front image corresponding to the target blood vessel, the data collection unit 30 uses the OCT to control a three-dimensional data set of the fundus of the eye to be examined under the control of the collection control unit 11. To collect. The collected three-dimensional data set is sent to the data processing unit 40.

(S23-S26)
Steps S23, S24, S25 and S26 are respectively performed in the same manner as steps S2, S3, S4 and S5 of the first operation example.

  That is, the image forming unit 41 forms a blood vessel emphasized image of the area scanned in step S22. The blood vessel angle distribution acquisition unit 42 obtains an inclination angle (blood vessel angle distribution) at one or more positions of the target blood vessel based on the blood vessel emphasized image. The measurement position setting unit 43 sets a measurement position in the target blood vessel based on this blood vessel angle distribution.

  At this time, the measurement position setting unit 43 can set one of a plurality of positions represented in the blood vessel angle distribution as the measurement position. Typically, based on the evaluation result obtained by the evaluation processing unit 431, one of a plurality of positions can be selected. The measurement position setting method is not limited to this. For example, the measurement position setting unit 43 sets a position near one of a plurality of positions represented in the blood vessel angle distribution as a measurement position, or two positions. It is also possible to set a position in between as a measurement position.

  Then, the OCT blood flow measurement of the blood vessel of interest is performed by the collection control unit 11, the data collection unit 30, the blood flow information generation unit 44, and the like.

<Fourth operation example>
In the fourth operation example, an attention vessel mode different from the third operation example will be described. In the third operation example, OCT angiography is performed on a region including the set target blood vessel, whereas in the fourth operation example, the target blood vessel is extracted from information obtained by OCT angiography over a relatively wide area. specify. The flow of processing executed in this example is shown in FIG.

(S31: Collect a three-dimensional data set by fundus OCT)
Step S31 is executed in the same manner as step S1 of the first operation example.

(S32: Designate the target blood vessel)
The target blood vessel is designated manually or automatically.

  When manually specifying the target blood vessel, for example, the display control unit 12 displays the projection image of the three-dimensional data set collected in step S31 on the display device 2. The user designates a desired blood vessel in the projection image displayed on the display device 2 by using the operation unit 50. Note that the target blood vessel may be specified for the front image acquired by the front image acquisition unit 60 or the blood vessel emphasized image based on the three-dimensional data set collected in step S31. Such a process can be executed in the same manner as S21 in the third operation example. The case of automatically specifying the target blood vessel can also be executed in the same manner as S21 in the third operation example.

(S33-S36)
Steps S33, S34, S35 and S36 are respectively performed in the same manner as steps S23, S24, S25 and S26 of the third operation example.

<Second Embodiment of Ophthalmic Imaging Device>
Another exemplary embodiment of the ophthalmic imaging apparatus will be described. In the present embodiment, a measurement mode that is different from the noted blood vessel mode described above will be described. The measurement mode of the present embodiment is used to estimate the total blood flow in the fundus (total blood flow mode).

  In order to estimate the total blood flow, it is necessary to distinguish between an artery and a vein. This is because if this determination is not performed, the blood flow flowing into the fundus and the blood flow flowing out from the fundus are counted redundantly. A configuration example of the ophthalmologic photographing apparatus according to the present embodiment is shown in FIG.

  The ophthalmologic photographing apparatus 1A is different from the ophthalmic photographing apparatus 1 of the first embodiment in that a classification processing unit 45 is provided in the data processing unit 40. Elements similar to those in the first embodiment are denoted by the same reference numerals. Unless otherwise stated, the elements of the ophthalmologic photographing apparatus 1A have the same configuration as the first embodiment and perform the same operation.

  The classification processing unit 45 classifies the plurality of blood vessels depicted in the blood vessel emphasized image formed by the image forming unit 41 into an artery and a vein. Here, “classification” is not only a process of dividing a plurality of objects into two or more types (categories) according to a predetermined standard, but a process of extracting one or more types from a plurality of objects according to a predetermined standard In addition, processing including specifying a target corresponding to one or more types among a plurality of targets according to a predetermined standard is also included.

  Therefore, for example, the classification processing unit 45 extracts a blood vessel corresponding to an artery (vein) from the plurality of blood vessels, a process of classifying a plurality of blood vessels depicted in the blood vessel emphasized image into an arterial category and a vein category. It may be possible to execute at least one of processing and processing for specifying a blood vessel corresponding to an artery (vein) among a plurality of blood vessels. Note that not all blood vessels need to be classified. For example, only blood vessels having a diameter greater than or equal to a predetermined threshold can be targeted for classification processing.

  An example of processing executed by the classification processing unit 45 will be described. For example, the classification processing unit 45 determines, for each of at least some of the plurality of blood vessels depicted in the front image of the fundus acquired by the front image acquisition unit 60, whether the blood vessel is an artery or a vein. . This determination can be made based on, for example, the pixel value of the front image, the crossing state of the blood vessels, the blood column reflection, and the like (see JP 2007-319403 A). The classification processing unit 45 reflects the classification result using the front image on the blood vessel emphasized image by performing registration between the front image and the blood vessel emphasized image, for example. Thereby, it is possible to classify the plurality of blood vessels depicted in the blood vessel emphasized image into an artery group and a vein group.

  In another example, the classification processing unit 45 can also determine the artery / vein based on the blood vessel distribution and the phase image obtained from the blood vessel enhancement image. Specifically, the classification processing unit 45 can first obtain the blood vessel path from the optic disc to a predetermined position based on the blood vessel enhancement image. Next, the classification processing unit 45 can obtain the blood flow direction of the blood vessel at the position based on the phase image. Then, the classification processing unit 45 can determine whether the blood vessel is an artery or a vein based on the route obtained from the blood vessel enhancement image and the blood flow direction obtained from the phase image. Thereby, a blood vessel group (arterial group) classified into an artery and / or a blood vessel group (vein group) classified into a vein are obtained. Since the blood vessel emphasized image and the phase image are images created from the same three-dimensional data set, registration between them is not necessary.

  An example of operations that can be executed by the ophthalmologic photographing apparatus 1A according to the present embodiment will be described. The flow of processing executed in this example is shown in FIG.

(S41-S43)
Steps S41, S42, and S43 are respectively performed in the same manner as steps S1, S2, and S3 of the first operation example.

(S44: classify a plurality of fundus blood vessels into arteries / veins)
The classification processing unit 45 classifies the plurality of fundus blood vessels depicted in the blood vessel emphasized image formed in step S42 into an artery and a vein. In this example, it is assumed that an arterial group is extracted. As described above, in this step S44, for example, the front image of the fundus acquired by the front image acquisition unit 60 at an arbitrary timing can be referred to.

(S45: The measurement position of each artery (each artery) is set)
The measurement position setting unit 43 sets the measurement positions of the blood vessels included in the artery group extracted in step S44. This process is executed by applying the same process as step S4 of the first operation example to each of the blood vessels included in this artery group.

(S46: OCT blood flow measurement of the arterial group (vein group) is performed to determine the total blood flow)
The ophthalmologic imaging apparatus 1 performs OCT blood flow measurement at each of the measurement positions set in step S45. OCT blood flow measurement at each measurement position is performed in the same manner as in step S5 of the first operation example.

  An example of the process in step S46 will be described. First, the control unit 10 (or the data processing unit 40 or the like) assigns an order to the plurality of measurement positions set in step S45. For example, the order is assigned clockwise or counterclockwise with reference to a predetermined direction (upward, downward, nose side, ear side, etc.), or the order is assigned in order from a measurement position close to a predetermined part (optic nerve head, etc.) It is possible to assign the order according to the shape (thickness etc.) of the blood vessel.

  Next, the control unit 10 (or the data processing unit 40 or the like) sets the first cross section (and the second cross section) based on each of the plurality of measurement positions set in step S45. Thereby, one first cross section is set for each of the blood vessels included in the artery group.

  Under the control of the collection control unit 11, the data collection unit 30 controls the plurality of first cross sections set for the arterial group to sequentially and repeatedly scan in accordance with the above order. Here, the repeated scanning method for the plurality of first cross sections may be a method in which all the first cross sections are finally scanned a predetermined number of times. The data collected by the data collection unit 30 is sent to the blood flow information generation unit 44. If the second cross section is also set, the scanning is also executed.

  The blood flow information generation unit 44, for each of a plurality of first cross sections corresponding to a plurality of blood vessels included in the artery group, the first data collected by repeated scanning of the first cross section, and the inclination at the corresponding measurement position Based on the angle, the blood flow in this blood vessel is calculated. This process is executed in the same manner as in the first embodiment. Thereby, each blood flow volume of the some blood vessel contained in an artery group is obtained.

  The blood flow information generation unit 44 calculates a total blood flow based on a plurality of blood flows calculated for a plurality of blood vessels (that is, a plurality of measurement positions set by the measurement position setting unit 43) included in the artery group. . This calculation process may include, for example, a process of calculating the sum of a plurality of blood flows corresponding to a plurality of blood vessels.

  The blood flow information generation unit 44 may execute a process of correcting any value of the plurality of blood flows based on a predetermined factor or a process of correcting the value of the total blood flow based on a predetermined factor. . For example, the value of the blood flow rate can be corrected according to the shape (thickness, meandering state, etc.) and position of the blood vessel. Further, when a blood vessel having a diameter less than the predetermined threshold is excluded from the calculation, a correction for adding the excluded blood flow may be performed.

  In another example, the blood flow information generation unit 44 obtains the total blood flow related to the artery and the total blood flow related to the vein, and can calculate a statistical value based on these. Alternatively, the blood flow information generation unit 44 can perform OCT blood flow measurement a plurality of times to obtain a plurality of total blood flow amounts and calculate a statistical value based on these.

<Third embodiment of an ophthalmologic photographing apparatus>
Another exemplary embodiment of the ophthalmic imaging apparatus will be described. In the present embodiment, the evaluation of the inclination angle and the setting of the measurement position according to each eye to be examined are realized by detecting the size of the pupil of the eye to be examined and correcting the angle condition information. A configuration example of such an ophthalmologic photographing apparatus is shown in FIG.

  The ophthalmologic photographing apparatus 1B is different from the ophthalmic photographing apparatus 1 of the first embodiment in that a pupil size information acquiring unit 46 is provided in the data processing unit 40. Elements similar to those in the first embodiment are denoted by the same reference numerals. Unless otherwise stated, the elements of the ophthalmologic photographing apparatus 1B have the same configuration as the first embodiment and perform the same operation.

  The pupil size information acquisition unit 46 acquires pupil size information indicating the size of the pupil of the eye to be examined. The pupil size is expressed as, for example, the diameter or area of the pupil or the diameter or area of the approximate circle (or approximate ellipse) of the pupil.

  The pupil size information acquisition unit 46 can acquire the pupil size information by analyzing, for example, an anterior segment image of the eye to be examined. As an example in this case, the front image acquisition unit 60 acquires a front image (anterior eye image) of the anterior eye part of the eye to be examined. The anterior segment image is acquired by, for example, a fundus camera, a slit lamp microscope, or the like. It is also possible to use a projection image or shadowgram based on a three-dimensional data set collected by the anterior segment OCT as the anterior segment image. For example, the pupil size information acquisition unit 46 can specify a pupil region based on the pixel value of the anterior segment image, approximate the contour of the pupil region to a circle or an ellipse, and obtain the diameter of the circle or ellipse. If the pupil diameter is determined, the area of the pupil region can be (substantially) determined, so that the pupil area can be used instead of the pupil diameter.

  In another example, the pupil size information acquisition unit 46 may include a communication device for acquiring pupil size information of the eye to be examined from an external device (such as an electronic medical record system) via a communication line.

  The evaluation processing unit 431 changes at least one of the one or more angle conditions included in the angle condition information based on the pupil size information acquired by the pupil size information acquisition unit 46. In the angle condition information 21a shown in FIG. 2, an M-rank angle condition that can correct the tilt angle to a suitable range “75 to 80 degrees” by shifting the measurement light as shown in FIG. The N-rank angle condition that cannot be corrected is changed.

  In the process of changing the angle condition, the relational expression Δθ = arctan (d / T) described above is referred to. Here, as shown in FIG. 3, Δθ is an angle formed by the measurement path LS0 and the measurement path LS1 at the fundus, d is a shift distance of the measurement path LS1 with respect to the measurement path LS0, and T is the eye to be examined. This is the length of the measurement optical path LS0. The pupil size is a limiting condition for the shift distance d of the measurement path. The larger the pupil, the larger the shift distance d. Typically, a half value of the pupil diameter (that is, the pupil radius) can be set to the maximum value of the shift distance d.

  An operation example of this embodiment will be described. The flow of processing executed in this example is shown in FIG. This is an example in which correction of angle condition information is added to the first operation example of the first embodiment, but the same applies to correction of angle condition information in other operation examples or other embodiments. It is.

(S51: Acquire pupil size information)
First, pupil size information of the eye to be examined is acquired by the pupil size information acquisition unit 46 and the like.

(S52: Change angle condition information)
The evaluation processing unit 431 changes at least one of the one or more angle conditions included in the angle condition information (21a) based on the pupil size information acquired in step S51.

  Depending on the value indicated by the pupil size information, the angle condition information may not be changed. For example, when the angle condition information is created for a predetermined range of pupil sizes, it is not necessary to change the angle condition information when the value indicated by the pupil size information obtained in step S51 is included in the predetermined range.

(S53-S55)
Steps S53, S54, and S55 are executed in the same manner as steps S1, S2, and S3 of the first operation example, respectively.

(S56: The measurement position is set with reference to the changed angle condition information)
The evaluation processing unit 431 evaluates the inclination angle of the blood vessel based on the angle condition information changed in step S52 and the blood vessel angle distribution obtained in step S55. The measurement position setting unit 43 sets the measurement position based on the evaluation result obtained by the evaluation processing unit 431. This process is executed in the same manner as in the first embodiment.

(S57: OCT blood flow measurement is performed)
The ophthalmologic imaging apparatus 1B performs OCT blood flow measurement at the measurement position set in step S56 in the same manner as in step S5 of the first operation example.

<Fourth Embodiment of Ophthalmic Imaging Device>
Another exemplary embodiment of the ophthalmic imaging apparatus will be described. In the present embodiment, the angle condition information is corrected by estimating the pupil diameter when the mydriatic agent is applied from the size of the pupil of the eye to be examined in a state where the mydriatic agent is not applied. As a result, it is possible to simulate evaluation assuming application of a mydriatic agent. An example of the configuration of such an ophthalmologic photographing apparatus is shown in FIG.

  The ophthalmologic photographing apparatus 1C is different from the ophthalmic photographing apparatus 1B of the third embodiment in that a pupil size estimating unit 47 is provided in the data processing unit 40. Elements similar to those in the third embodiment are denoted by the same reference numerals. Unless otherwise stated, the elements of the ophthalmologic photographing apparatus 1C have the same configuration as the first embodiment or the third embodiment and perform the same operation.

  As described above, the pupil size information acquisition unit 46 acquires pupil size information indicating the size of the pupil of the eye to be examined. In the present embodiment, the pupil size in a state where a mydriatic agent is not applied (that is, a state without a mydriasis) is acquired. For example, by analyzing the anterior segment image obtained by photographing the anterior segment of the subject's eye in a state where no mydriatic agent is applied, the pupil size information in the state where the mydriatic agent is not applied is analyzed. Can be acquired. Further, such pupil size information may be acquired from an external device (such as an electronic medical record system) via a communication line.

  The pupil size estimation unit 47 estimates the size of the pupil of the eye to be examined in a state where the mydriatic agent is applied based on the pupil size information acquired by the pupil size information acquisition unit 46. This estimation is performed, for example, with reference to any of the following: a standard value of the amount of change in pupil size caused by a mydriatic (such as clinically obtained statistical values); The amount of change in pupil size when the agent is applied.

  Such reference information can be prepared for each of two or more types of mydriatics. Also, reference information can be prepared in stages according to the value of the pupil size at the time of non-mydriatic. Also, a plurality of reference information can be prepared according to arbitrary factors such as a diagnosis name (a definite diagnosis name, a suspected diagnosis name, etc.), a drug to be administered, a medical history, a drug history, an age, and a sex. Information regarding such factors is obtained from, for example, an electronic medical record system.

  The evaluation processing unit 431 changes at least one of the one or more angle conditions included in the angle condition information based on the pupil size estimated by the pupil size estimation unit 47. The change of the angle condition is executed in the same manner as in the third embodiment.

  An operation example of this embodiment will be described. The flow of processing executed in this example is shown in FIG. This is an example in which the estimation of the pupil size is added to the operation example of the third embodiment, but the same applies to the case where the estimation of the pupil size is added to the other operation examples or other embodiments.

(S61: Acquire pupil size information)
First, pupil size information of the eye to be examined is acquired by the pupil size information acquisition unit 46 and the like.

(S62: Estimate pupil size at the time of mydriasis)
The pupil size estimation unit 47 estimates the pupil size of the eye to be inspected at the time of mydriasis based on the pupil size information (and the aforementioned reference information) acquired in step S61.

(S63: Change angle condition information)
The evaluation processing unit 431 changes at least one of the one or more angle conditions included in the angle condition information (21a) based on the pupil size estimated in step S62. The angle condition information may not be changed depending on the value indicated by the estimated pupil size.

(S64-S66)
Steps S64, S65, and S66 are respectively performed in the same manner as steps S1, S2, and S3 of the first operation example.

(S67: The measurement position is set with reference to the changed angle condition information)
The evaluation processing unit 431 evaluates the inclination angle of the blood vessel based on the angle condition information changed in step S63 and the blood vessel angle distribution obtained in step S66. The measurement position setting unit 43 sets the measurement position based on the evaluation result obtained by the evaluation processing unit 431. This process is executed in the same manner as in the first embodiment.

(S68: OCT blood flow measurement is performed)
The ophthalmologic imaging apparatus 1B performs OCT blood flow measurement at the measurement position set in step S67 in the same manner as in step S5 of the first operation example.

<Action and effect>
The operation and effect of an exemplary ophthalmologic photographing apparatus will be described.

  An exemplary ophthalmic imaging apparatus (1, 1A, 1B, 1C) includes a data collection unit (30), a blood vessel enhancement image formation unit (image formation unit 41), a blood vessel angle distribution acquisition unit (42), and a measurement position. A setting unit (43), a collection control unit (11), and a blood flow information generation unit (44) are provided.

  The data collection unit can collect a three-dimensional data set of the fundus of the eye to be examined using OCT. The blood vessel enhanced image forming unit can form a blood vessel enhanced image based on the three-dimensional data set. The blood vessel angle distribution acquisition unit can obtain a blood vessel angle distribution representing the inclination angle of the blood vessel at one or more positions of the fundus based on the blood vessel emphasized image. The measurement position setting unit can set a measurement position to be subjected to OCT blood flow measurement based on the blood vessel angle distribution. The acquisition control unit can control the data acquisition unit to repeatedly scan the first cross section intersecting the blood vessel at the measurement position. The blood flow information generation unit generates blood flow information representing a blood flow state in the blood vessel based on the first data collected by repeated scanning of the first cross section and the inclination angle of the blood vessel at the measurement position. Can do.

  In the embodiment, the collection control unit can control the data collection unit to scan one or more second cross sections that intersect the blood vessel in the vicinity of the measurement position set by the measurement position setting unit. The blood flow information generation unit can calculate the inclination angle of the blood vessel at the measurement position based on the second data collected by scanning the second cross section. Furthermore, the blood flow information generation unit can generate blood flow information based on the calculated inclination angle and the first data.

  The exemplary ophthalmologic photographing apparatus (1, 1A, 1B, 1C) may include a front image acquisition unit (60) and a display control unit (12). The front image acquisition unit can acquire a front image (an observation image, a captured image, etc.) of the fundus. The display control unit can cause the display means (display device 2) to display the measurement position image representing the measurement position set by the measurement position setting unit on the front image acquired by the front image acquisition unit.

  In an embodiment, the ophthalmologic imaging apparatus may be configured to operate according to one or more measurement modes. As an example of the measurement mode, there is a target blood vessel mode in which blood flow measurement is performed by searching for a measurement position of a specific blood vessel. In the exemplary ophthalmologic imaging apparatus (1) for realizing the focused blood vessel mode, when a blood vessel in the fundus is designated in advance, the blood vessel angle distribution acquisition unit displays the blood vessel angle distribution representing the inclination angles at a plurality of positions of the blood vessel. Can be requested. Furthermore, the measurement position setting unit can set the measurement position of the blood vessel based on the blood vessel angle distribution.

  In the focused blood vessel mode, the measurement position setting unit selects one of a plurality of positions represented in the blood vessel angle distribution as the measurement position of the blood vessel based on the blood vessel angle distribution acquired for the designated blood vessel. be able to.

  As another example of the measurement mode, there is a total blood flow mode for estimating the total blood flow in the fundus. The exemplary ophthalmologic imaging apparatus (1A) for realizing the whole blood flow mode may include a classification processing unit (45). The classification processing unit can classify a plurality of blood vessels depicted in the blood vessel enhancement image into an artery and a vein. The measurement position setting unit sets, for at least one of a blood vessel group classified as an artery (arterial group) and a blood vessel group classified as a vein (vein group), a measurement position of each blood vessel included in the blood vessel group. Can do.

  In the whole blood flow mode, the collection control unit can control the data collection unit to sequentially and repeatedly scan a plurality of first cross sections based on a plurality of measurement positions set for the blood vessel group. The blood flow information generation unit, for each of the plurality of first cross sections, based on the first data collected by repeated scanning of the first cross section and the inclination angle at the corresponding measurement position, the blood flow volume in the corresponding blood vessel Can be calculated. Furthermore, the blood flow information generation unit can calculate a total blood flow (estimated value) based on a plurality of blood flows calculated for a plurality of measurement positions set for the blood vessel group.

  In the embodiment, the measurement position setting unit may include an evaluation processing unit (431). The evaluation processing unit can evaluate suitability as a target position for OCT blood flow measurement based on the inclination angle at each of one or more positions represented in the blood vessel angle distribution. The measurement position setting unit can set the measurement position based on the evaluation result obtained by the evaluation processing unit.

  In the embodiment, the evaluation processing unit compares the inclination angle at each of the one or more positions represented in the blood vessel angle distribution with the angle condition information (21a) representing the one or more angle conditions, thereby obtaining the OCT blood flow. It is possible to evaluate suitability as a measurement target position.

  The exemplary ophthalmologic imaging apparatus (1B, 1C) may include a pupil size information acquisition unit (46). The pupil size information acquisition unit can acquire pupil size information indicating the size of the pupil of the eye to be examined. The evaluation processing unit can change at least one of the one or more angle conditions represented in the angle condition information based on the acquired pupil size information. The evaluation processing unit can evaluate suitability as a target position for OCT blood flow measurement using angle condition information in which one or more angle conditions are changed.

  The exemplary ophthalmologic imaging apparatus (1C) may include a pupil size estimation unit (47). In this case, the pupil size information acquisition unit can acquire pupil size information indicating the size of the pupil of the eye to be examined in a state where no mydriatic agent is applied. The pupil size estimation unit can estimate the size of the pupil of the eye to be examined in a state where the mydriatic agent is applied based on the acquired pupil size information. The evaluation processing unit can change at least one of the one or more angle conditions represented in the angle condition information based on the pupil size estimated by the pupil size estimation unit. The evaluation processing unit can evaluate suitability as a target position for OCT blood flow measurement using angle condition information in which one or more angle conditions are changed.

  In the embodiment, the blood vessel angle distribution can determine the inclination angle of the blood vessel with respect to the A scan direction in OCT.

  According to such an embodiment, a blood vessel angle distribution is automatically obtained based on a (three-dimensional) blood vessel enhancement image obtained by OCT angiography, and a measurement position for OCT blood flow measurement is based on the blood vessel angle distribution. Is automatically set, and OCT blood flow measurement at this measurement position can be performed. Therefore, it is possible to automatically perform OCT blood flow measurement by searching for a position where the direction of the blood vessel is suitable. Therefore, the burden placed on the examiner or the subject in OCT blood flow measurement can be reduced.

  The operations and effects of the embodiments are not limited to these, and the operations and effects provided by the respective items described as the embodiments and the operations and effects provided by a combination of a plurality of items should be considered. In addition, any of the above-described embodiments, other embodiments, known techniques, and the like can be arbitrarily combined in order to obtain a desired action and / or effect, or for other purposes.

  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.

1, 1A, 1B, 1C Ophthalmologic imaging apparatus 2 Display device 10 Control unit 11 Collection control unit 12 Display control unit 20 Storage unit 21 Condition information 21a Angle condition information 30 Data collection unit 40 Data processing unit 41 Image forming unit 42 Blood vessel angle distribution Acquisition unit 43 Measurement position setting unit 431 Evaluation processing unit 44 Blood flow information generation unit 45 Classification processing unit 46 Pupil size information acquisition unit 47 Pupil size estimation unit 50 Operation unit 60 Front image acquisition unit

Claims (12)

A data collection unit that collects a three-dimensional data set of the fundus of the eye to be examined using optical coherence tomography (OCT);
A blood vessel emphasized image forming unit that forms a blood vessel emphasized image based on the three-dimensional data set;
A blood vessel angle distribution acquisition unit for obtaining a blood vessel angle distribution representing a blood vessel inclination angle at one or more positions of the fundus based on the blood vessel enhancement image;
Based on the blood vessel angle distribution, a measurement position setting unit that sets a measurement position to be subjected to OCT blood flow measurement;
A collection control unit that controls the data collection unit to repeatedly scan a first cross section that intersects a blood vessel at the measurement position;
A blood flow information generation unit configured to generate blood flow information representing a blood flow state in the blood vessel based on the first data collected by repeated scanning of the first cross section and the inclination angle of the blood vessel at the measurement position; An ophthalmologic photographing apparatus comprising: The collection control unit controls the data collection unit to scan one or more second cross sections intersecting the blood vessel in the vicinity of the measurement position;
The blood flow information generation unit calculates an inclination angle of the blood vessel at the measurement position based on second data collected by scanning the second cross section, and calculates the calculated inclination angle and the first data. The ophthalmic imaging apparatus according to claim 1, wherein the blood flow information is generated based on the information. A front image acquisition unit for acquiring a front image of the fundus;
The ophthalmologic photographing apparatus according to claim 1, further comprising: a display control unit configured to display a measurement position image representing the measurement position on a display unit so as to overlap the front image. The blood vessel angle distribution acquisition unit obtains a blood vessel angle distribution representing inclination angles at a plurality of positions of a blood vessel designated in advance,
The ophthalmic imaging apparatus according to claim 1, wherein the measurement position setting unit sets a measurement position of the blood vessel based on the blood vessel angle distribution. The ophthalmic imaging apparatus according to claim 4, wherein the measurement position setting unit selects one of the plurality of positions as a measurement position of the blood vessel based on the blood vessel angle distribution. A classification processing unit that classifies a plurality of blood vessels depicted in the blood vessel emphasized image into arteries and veins,
The said measurement position setting part sets each measurement position of the blood vessel contained in the said blood vessel group about at least one of the blood vessel group classified into the artery and the blood vessel group classified into the vein. The ophthalmologic photographing apparatus according to any one of? The collection control unit controls the data collection unit to sequentially and repeatedly scan a plurality of first cross sections based on a plurality of measurement positions set for the blood vessel group;
The blood flow information generation unit
For each of the plurality of first cross sections, based on the first data collected by repeated scanning of the first cross section and the inclination angle at the measurement position, the blood flow in the blood vessel is calculated,
The ophthalmologic imaging apparatus according to claim 6, wherein a total blood flow is calculated based on a plurality of blood flows calculated for the plurality of measurement positions. The measurement position setting unit
An evaluation processing unit that evaluates suitability as a target position of OCT blood flow measurement based on an inclination angle at each of the one or more positions;
The ophthalmologic photographing apparatus according to claim 1, wherein the measurement position is set based on an evaluation result obtained by the evaluation processing unit. The evaluation processing unit evaluates the suitability by comparing an inclination angle at each of the one or more positions with angle condition information representing one or more angle conditions. The ophthalmic imaging apparatus described. A pupil size information acquisition unit for acquiring pupil size information representing the size of the pupil of the eye to be examined;
The ophthalmologic photographing apparatus according to claim 9, wherein the evaluation processing unit changes at least one of the one or more angle conditions based on the pupil size information. The pupil size information acquisition unit acquires pupil size information indicating the size of the pupil of the eye to be examined in a state where a mydriatic agent is not applied,
Based on the pupil size information, comprising a pupil size estimation unit that estimates the size of the pupil of the eye in a state in which a mydriatic is applied,
The ophthalmologic imaging apparatus according to claim 10, wherein the evaluation processing unit changes at least one of the one or more angle conditions based on a pupil size estimated by the pupil size estimation unit. The ophthalmologic imaging apparatus according to any one of claims 1 to 11, wherein the blood vessel angle distribution obtains an inclination angle of a blood vessel with respect to an A scan direction in OCT.