JP6864450B2 - Ophthalmologic imaging equipment - Google Patents

Description

The present invention relates to an ophthalmologic imaging apparatus.

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

Further, it is also performed to acquire an image emphasizing a specific part of the eye to be inspected and to acquire functional information. For example, based on the time-series volume data collected by OCT, a B-mode image or anterior 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 or the like. In addition, blood flow information can be acquired based on the phase information of the data collected by OCT. This technique is called OCT blood flow measurement or the like.

Special Table 2015-515894 Japanese Unexamined Patent Publication No. 2013-184018

In OCT blood flow measurement, it is necessary to estimate the orientation of the target blood vessel. This is because the blood flow information is obtained by using the Doppler frequency shift that changes according to the angle between the incident direction of the measurement light with respect to the blood vessel and the direction of the blood flow (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 by referring to the frontal image of the fundus obtained by the fundus camera or SLO (Scanning Laser Ophthalmoscope), it is not possible to grasp the orientation component of the blood vessel that affects the Doppler frequency shift. It was difficult. Therefore, the examiner and the subject are burdened with time and labor, such as evaluating the orientation of the blood vessel obtained by performing the preparatory measurement and searching for a suitable blood vessel.

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

The ophthalmologic imaging apparatus according to the exemplary embodiment is classified into a data collection unit, a blood vessel emphasis 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 . It is equipped with a processing unit. The data collection unit collects a three-dimensional data set of the fundus of the eye to be inspected using optical coherence tomography (OCT). The blood vessel-enhanced image forming unit forms a blood vessel-enhanced image based on the three-dimensional data set collected by the data collecting unit by OCT angiography. Based on the blood vessel-enhanced image formed by the blood vessel-enhanced image forming unit, the blood vessel angle distribution acquisition unit obtains a blood vessel angle distribution representing the inclination angle of the blood vessel with reference to the A scan direction at one or more positions of the fundus of the eye. The measurement position setting unit sets the measurement position to be the target 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 so as to repeatedly scan the first cross section intersecting the blood vessel at the measurement position set by the measurement position setting unit. The blood flow information generation unit determines the first data collected by the data collection unit by repeated scanning of the first cross section and the inclination angle of the blood vessel based on the A scan direction at the measurement position set by the measurement position setting unit. Based on this, blood flow information representing the blood flow state in this blood vessel is generated. The classification processing unit classifies a plurality of blood vessels depicted in the blood vessel-enhanced image formed by the blood vessel-enhanced image forming unit into arteries and veins. The measurement position setting unit sets the measurement positions of the blood vessels included in the blood vessel group for at least one of the blood vessel group classified into the artery and the blood vessel group classified into the vein.

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

The schematic which shows the structure of the exemplary ophthalmologic imaging apparatus. The schematic which shows the structure of the exemplary ophthalmologic imaging apparatus. The schematic diagram for demonstrating the process performed by an exemplary ophthalmologic imaging apparatus. The schematic diagram for demonstrating the process performed by an exemplary ophthalmologic imaging apparatus. The flowchart which shows the operation of the exemplary ophthalmologic imaging apparatus. The flowchart which shows the operation of the exemplary ophthalmologic imaging apparatus. The schematic diagram for demonstrating the operation of an exemplary ophthalmologic imaging apparatus. The flowchart which shows the operation of the exemplary ophthalmologic imaging apparatus. The flowchart which shows the operation of the exemplary ophthalmologic imaging apparatus. The schematic which shows the structure of the exemplary ophthalmologic imaging apparatus. The flowchart which shows the operation of the exemplary ophthalmologic imaging apparatus. The schematic which shows the structure of the exemplary ophthalmologic imaging apparatus. The flowchart which shows the operation of the exemplary ophthalmologic imaging apparatus. The schematic which shows the structure of the exemplary ophthalmologic imaging apparatus. The flowchart which shows the operation of the exemplary ophthalmologic imaging apparatus.

An exemplary embodiment of the present invention will be described with reference to the drawings. In addition, the matters described in the document cited in this specification can be incorporated into the embodiment.

In the embodiment, OCT angiography is used to determine the tilt angle of a blood vessel at one or more positions of the fundus. By associating the position of the fundus with the inclination angle of the blood vessel, the distribution of the inclination angle of the fundus blood vessel (blood vessel angle distribution) can be obtained. The vascular angle distribution can be used, for example, for diagnostics and other modality. OCT blood flow measurement is a typical example of another modality.

The inclination angle of the blood vessel may be defined with reference to an arbitrary direction (angle = 0 degrees). For example, the direction of A (Axial) scan in OCT (direction of A line) can be used as a reference. The reference direction of the inclination angle of the blood vessel may be set in common for all the 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 vessel-enhanced image is formed based on a three-dimensional data set containing a plurality of two-dimensional data sets obtained thereby. In the three-dimensional data set, for example, a plurality of B cross sections (cross sections) are scanned a predetermined number of times (for example, four times each) to form a predetermined number of images (B mode images) in each B cross section, and these are formed. It is obtained by embedding it in the same 3D coordinate system (and by voxelizing it). Such an image forming technique is known.

The ophthalmologic imaging apparatus of 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 capable of performing, for example, a Fourier domain OCT.

Fourier domain OCT includes spectral domain OCT and swept source OCT. Spectral domain OCT is a method of imaging an eye to be inspected by acquiring a spectrum of interference light by spatial division using a wideband low coherence light source and a spectroscope, and Fourier transforming the spectrum. The swept source OCT uses a wavelength sweep light source (wavelength variable light source) and a photodetector (balanced photodiode, etc.) to acquire the spectrum of interference light in a time-divided manner, and Fourier transforms the spectrum to obtain the eye to be inspected. It is a method of imaging. The method of OCT is not limited to Fourier domain OCT, and may be time domain OCT or Enface OCT.

The ophthalmologic imaging apparatus may include a modality for imaging the eye and / or other parts (eg, a modality other than OCT). Typical examples thereof include fundus cameras, SLOs, slit lamp microscopes, and microscopes for ophthalmic surgery. In addition, the ophthalmologic imaging apparatus may include a configuration for measuring the characteristics of the eye and / or other parts, and a configuration for performing an examination.

The data processing functions (calculation function, image processing function, control function, etc.) in the ophthalmologic imaging apparatus according to the embodiment include, for example, hardware such as a processor and a storage device, and software such as an arithmetic program, an image processing program, and a control program. Is realized by the cooperation of. A part of the hardware may be provided in an external device capable of communicating with the ophthalmologic imaging device. Also, at least a portion of the software may be pre-stored in an ophthalmologic imaging device and / or may be pre-stored in an external device.

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

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

The ophthalmologic imaging device 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 imaging device 1. The control unit 10 includes a processor. The "processor" includes, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), a programmable logic device (for example, a SPLD (Simple Programmable)). , FPGA (Field Programmable Gate Array)) and the like. The control unit 10 can realize the function according to the embodiment by reading and executing a program stored in a storage circuit or a storage device (storage unit 20, an external device, etc.), for example.

Further, the control unit 10 may include a communication device for transmitting / receiving data via a communication line such as a local area network (LAN), the Internet, or 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 to control the light source, control the optical scanner, change the optical path length of the measurement light and / or the reference light, adjust the polarization, adjust the amount of light, adjust the focus, change the fixation position, and the like. Control various elements for collecting data. Some examples of processes 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, composition, etc.) related to the information displayed on the display device 2. For example, the display control unit 12 converts the evaluation result distribution (or information obtained from it), the blood vessel angle distribution (or information obtained from it), and the like into an image (front image) acquired by the front image acquisition unit 60. It can be displayed in layers. Further, the display control unit 12 generates a composite image of the evaluation result distribution (or information obtained from it) and the front image, or a composite image of the blood vessel angle distribution (or information obtained from it) and the front image. Can be done.

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

<Memory 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 relating to the inclination angle of the blood vessel, and is referred to by the measurement position setting unit 43 (evaluation processing unit 431) described later. Some examples of the conditions included in the condition information 21 will be described.

The first example of the condition is the angular condition information for OCT blood flow measurement. Since the Doppler OCT signal is used in the OCT blood flow measurement, a good signal cannot be obtained unless the angle between the projection direction (A scan direction) of the measurement light 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 projection position of the measurement light. 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. Conditions may include a threshold and / or range of tilt angles. Further, the angle condition information may include a condition regarding the eye to be inspected and a condition regarding the relationship between the eye to be inspected and the ophthalmologic imaging apparatus 1. Pupil diameter is an example of a condition relating to an eye to be inspected. As an example of the condition regarding the relationship between the eye to be inspected and the ophthalmologic imaging device 1, there is a relative position between the eye to be inspected and the optical system of the ophthalmologic photographing apparatus 1 (for example, the displacement between the axis of the eye to be inspected and the axis of the optical system).

An example of the angle condition information is shown in FIG. The angle condition information 21a is included in the condition information 21. The angle condition information 21a is, for example, table information including an evaluation column and an angle condition column. In the evaluation column, "H", "M", and "N" are given as evaluation ranks. In the angle condition column, as conditions related to the inclination angle of the blood vessel, the angle condition "75 to 80 degrees" corresponding to H rank and the angle condition "correctable to 75 to 80 degrees" corresponding to M rank are displayed in 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, H rank represents aptitude "high", M rank represents aptitude "medium", and N rank represents aptitude "none".

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

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

The correction process used for determining the M rank and the N rank will be described. The correction process includes, for example, a shift (change in relative position) of the path of the measurement light with respect to the axis of the eye to be inspected. The amount of this shift is limited to the pupil diameter. The pupil diameter may be a measured value of the eye to be inspected or a standard value (statistical value or the like). Further, 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 process, the evaluation processing unit 431 realizes a suitable angle condition "75 to 80 degrees" when the path of the measurement light is shifted with respect to the axis of the eye to be inspected with the pupil diameter as a constraint condition. Judge whether or not. The relationship between the shift of the path of the measurement light with respect to the axis of the eye to be inspected and the change in the projection direction (A scan direction) of the measurement light 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 the same as the change in the inclination angle of the blood vessel.

See FIG. Each of the reference numerals LS0 and LS1 indicates a path (measurement path) of the measurement light. Outside the eye E to be inspected, the measurement paths LS0 and LS1 are parallel to each other and are separated by a distance d in the direction orthogonal to them. That is, the measurement path LS1 is a path shifted by a distance d with respect to the measurement path LS0. Further, let T be the length of the measurement optical path LS0 in the eye E to be inspected.

At this time, the angle Δθ formed by the measurement path LS0 and the measurement path LS1 on 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 contains 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, if the shift direction does not follow the length direction of the blood vessel (more generally, if the vector representing the shift does not include a component in the length direction of the blood vessel, or if the component is sufficiently small), the blood vessel tilt angle is corrected. Is not done.

A second example of the condition will be described. The second example is local angular 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 vessel tilt angle corresponding to the characteristic deformation of the vessel. As a typical example, a blood vessel in the fundus may protrude in the direction of the cornea or vice versa 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 with a position at an inclination angle of 90 degrees. .. The local angle 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, the position satisfying the condition represented by the local angle distribution information is selected as the target position for the 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 the condition will be described. The third example is the time-dependent angle change information for diagnosing the eye to be inspected. The local angular distribution information of the second example represents the shape of the blood vessel (at some point in time). On the other hand, the time-dependent angle change information of the third example represents the time-dependent change in the shape of the blood vessel. As a typical example, the deformation of blood vessels (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 the gradual decrease section of the inclination angle, changes in the width of the gradual increase section, changes in the height difference in the gradual decrease section, and changes in the height difference in the gradual increase section. , Change in slope in the gradual decrease section, change in slope in the gradual increase section, etc. The time-dependent angle change information includes at least one such characteristic change.

The information on the change in angle over time 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 can be selected as the target position for OCT blood flow measurement, or the condition represented by the temporal angle change information can be 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 inspected. 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 collection system (DAQ), a control system, and the like, as in the conventional case. 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 a measurement light and a reference light, projects the measurement light onto the eye to be inspected, and superimposes the return light of the measurement light from the eye to be inspected on the reference light to interfere with the light. To generate. The optical scanner includes a galvano scanner or the like and deflects the measurement light. The photodetector detects (spectrum) the interference light generated by the interference optics.

In OCT angiography, the data collection unit 30 scans a three-dimensional region of the eye to be inspected. The scan mode at that time is, for example, raster scan (three-dimensional scan). This 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, scan the plurality of B cross sections sequentially 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 the OCT blood flow measurement, the data collection unit 30 repeatedly scans the 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, for example, repeated at a predetermined frequency. The 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 determining the inclination angle of the blood vessel of interest in the cross section of interest. This scan is performed, for example, on two cross sections that intersect the blood vessel of interest. Here, the two cross sections can be arranged in the vicinity of the cross section of interest. Alternatively, one of the two cross sections may be arranged in the vicinity of the cross section of interest, while the other may be the cross section of interest. In this case, the data obtained by the repeated scanning of the cross section of interest described above can be used. That is, the scan performed by the OCT blood flow measurement may be a combination of a repeated scan of the cross section of interest and a scan of two other cross sections, or a repeated scan of the cross section of interest and a scan of another one cross section.

The mode of scanning for determining 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, a three-dimensional region including the cross section of interest can be scanned (three-dimensional scan). As another example, a cross section that intersects the cross section of interest and 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 inspected. As a typical example, the data processing unit 40 executes 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 technique.

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 each B cross section. Stack data and volume data are examples of three-dimensional datasets.

The image forming unit 41 performs various renderings on the three-dimensional data set to obtain a B-mode image (vertical cross-sectional image, axial cross-sectional image), a C-mode image (cross-sectional image, horizontal cross-sectional image), a projection image, and a shadow. It can form grams and the like. 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 designated cross section from a three-dimensional data set. The projection image is formed by projecting a three-dimensional data set in a predetermined direction (Z direction, depth direction, A scan direction). The shadow gram 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 with the front side of the eye to be inspected as a viewpoint, such as a C-mode image, a projection image, and a shadow gram, 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 finding a specific tissue or tissue boundary, and size analysis for finding 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 the B-mode image or the 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-enhanced image (angiogram). The blood vessel-enhanced image is an image in which an image region (blood vessel region) corresponding to a blood vessel is specified by analyzing OCT data, and the expression mode of this blood vessel region is changed to emphasize it. A plurality of OCT data obtained by repeatedly scanning substantially the same area of the eye to be inspected are used to identify the blood vessel region. In embodiments, a three-dimensional dataset is used to display a vessel-enhanced image as a planar image.

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

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

Subsequently, a process for identifying an image region that is changing among the plurality of aligned B-mode images is performed. This process includes, for example, a process of finding the difference between different B-mode images. Each B-mode image is luminance image data representing the morphology of the eye to be inspected, and it is considered that the image region corresponding to a portion other than the blood vessel is substantially unchanged. On the other hand, considering that the backscatter that contributes to the interference signal changes randomly due to the blood flow, the image region in which the change occurs between the plurality of aligned B-mode images (for example, pixels having a non-zero difference, or A pixel whose difference is equal to or greater than a predetermined threshold value) can be estimated to be a blood vessel region.

The image region thus identified is assigned information indicating that it is a blood vessel region. By performing the above processing on a plurality of B cross sections, a three-dimensionally distributed blood vessel region can be obtained. By rendering such a three-dimensional blood vessel-enhanced image, a front image showing the blood vessel distribution, an image of an arbitrary cross section, a shadow gram of an arbitrary range, and the like are generated.

The process of forming a blood vessel-enhanced image is not limited to this. For example, it is possible to specify the blood vessel region by a conventional method using Doppler OCT, or to specify the blood vessel region by using a conventional image processing method. In addition, it is possible to specify the blood vessel region for each site by using a different method depending on the site. For example, for the retina, the vascular region can be specified by using the above-mentioned typical method or the Doppler OCT method, and for the choroid, the vascular region can be specified by using the image processing method.

<Vessel angle distribution acquisition unit 42>
The blood vessel angle distribution acquisition unit 42 obtains the blood vessel angle distribution based on the three-dimensional blood vessel emphasized image formed by the image forming unit 41. This blood vessel angle distribution represents the tilt angle of the blood vessel at one or more positions of the fundus, and typically represents the tilt angle of the blood vessel at two or more positions. An example of how to obtain the inclination angle of a blood vessel will be described below. The position where the tilt angle is obtained may be, for example, the A scan position in the three-dimensional data set, or the 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 attention position by calculating the inclination at an arbitrary position (attention 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 slope by a differential operation. On the other hand, when the blood vessel axis model cannot be differentiated at the position of interest, for example, attention is paid based on the position of the blood vessel axis at the position of interest and the position of the blood vessel axis at a position close to the position (one or more nearby positions). The slope (approximate value) at the position can be calculated.

A second example will be described. See FIG. Reference numeral B0 indicates a tomographic image (attention tomographic image) representing a cross section (attention cross section) including the attention position where the blood vessel inclination angle is calculated. The 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 (nearby cross sections) located in the vicinity of the cross section of interest B0. In the nearby tomographic image B11, the blood vessel region V11 in another cross section of the same blood vessel (blood vessel of interest) as the blood vessel region V0 is depicted. Similarly, the nearby tomographic image B12 depicts the blood vessel region V12 in another cross section of the blood vessel of interest.

Here, for example, by applying a known process such as labeling or region glowing to a three-dimensional blood vessel-enhanced image, the position (distribution) of the blood vessel of interest can be grasped and a nearby cross section can be set. It is also possible to provide a display and a graphical user interface (GUI) for the user to set at least one of a cross section of interest and a cross section in the vicinity.

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 of interest and the tomographic images B11 and B12 of interest. The number of nearby tomographic images referred to is not limited to two, and may be any number of one or more.

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 the cross sections. The cross-section distance may include the distance between the nearby tomographic image B11 and the nearby tomographic image B12. Further, the intersection distance may include at least one of the distance between the nearby tomographic image B11 and the tomographic image B0 of interest and the distance between the tomographic image B12 of interest and the tomographic image B0 of interest. Let L be the distance between the tomographic image B11 (B12) in the vicinity and the tomographic image B0 of interest.

The A scan direction shown in FIG. 4 (the direction indicated by the arrow pointing downward) is located at the center of, for example, an A scan image included in the tomographic image B0 of interest (for example, a plurality of A scan images included in the tomographic image B0 of interest). The direction of the A scan image) is shown. 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 orientation A of the blood vessel of interest in the cross section of interest based on the positional relationship of the three blood vessel regions V0, V11, and V12. This positional relationship is obtained, for example, by connecting the three vascular regions V0, V11 and V12. Specifically, the blood vessel angle distribution acquisition unit 42 identifies the feature points of the three blood vessel regions V0, V11, and V12, and connects these feature points. The feature points include the center position (axis position), the center of gravity position, and the uppermost part. Further, as a method of connecting these feature points, there are a method of connecting with a line segment, a method of connecting with an approximate curve (spline curve, Bezier curve, etc.) and the like.

Further, the blood vessel angle distribution acquisition unit 42 calculates the orientation A based on the line connecting these feature points. When a line segment is used, the blood vessel angle distribution acquisition unit 42 is, for example, a first line segment connecting a feature point of the blood vessel region V0 in the tomographic image B0 of interest and a feature point of the blood vessel region V11 in the nearby tomographic image B11. The orientation A can be calculated based on the inclination and the inclination of the second line segment connecting the characteristic point of the vascular region V0 and the characteristic point of the vascular region V12 in the nearby tomographic image B12. As an example of this calculation process, the average value of the slopes of the 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 cross section of interest can be obtained.

In this example, the blood vessel regions in the three cross sections are taken into consideration, but it is also possible to obtain the inclination in consideration of the blood vessel regions in the two cross sections. As a specific example, the direction A of the blood vessel of interest in the cross section of interest can be obtained based on the blood vessel region V11 in the tomographic image B11 and the blood vessel region V12 in the tomographic image B12. Further, the direction A of the blood vessel of interest in the cross section of interest can be obtained based on the blood vessel region V11 in the nearby tomographic image B11 and the blood vessel region V0 in the tomographic image of interest B0. For example, the inclination of the first line segment or the second line segment can be obtained and adopted as the orientation A of the blood vessel of interest.

Further, in the above example, only one direction of the blood vessel is obtained and it is adopted as the direction A, but the inclination may be obtained for each of two or more positions (or regions) in the blood vessel region V0. In this case, the obtained two or more 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 orientation A.

<Measurement position setting unit 43>
The measurement position setting unit 43 sets the measurement position to be the target of 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 tilt angle of the blood vessel at one or more positions of the fundus, and typically represents the tilt angle of the blood vessel at two or more positions. The tilt angle is defined, for example, with reference to the A scan direction (incident direction of the OCT measurement light) at that position.

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

<Evaluation processing unit 431>
The evaluation processing unit 431 evaluates the 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 that satisfy 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 by the blood vessel angle distribution with the angle condition information, and this inclination angle (the position of the fundus corresponding to this) is OCT blood. It can be evaluated whether it is suitable for flow measurement. According to such a process, the evaluation rank can be assigned to at least a part of the 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 (corresponding position of the fundus) represented by the blood vessel angle distribution. Be done. Typically, the H rank position, the M rank position, and the N rank position can be specified respectively. Further, only the H rank position having a high degree of suitability for OCT blood flow measurement can be assigned. In addition, only M rank positions with moderate suitability 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 undergoes 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 the site of the blood vessel (the site where the blood vessel has a characteristic shape). As mentioned above, the characteristic deformation is, for example, a protrusion due to a tumor or fluid leakage. It is also possible to detect meandering of blood vessels and local changes in blood vessel diameter as characteristic deformations. In addition, the result of such processing can be used for evaluation of aptitude for OCT blood flow measurement.

When the time-dependent angle change information is used for evaluation, the evaluation processing unit 431 determines, for example, the time-dependent change in blood vessel shape based on the blood vessel angle distribution acquired by the blood vessel angle distribution acquisition unit 42 and the time-dependent angle change information. It is possible to identify a characteristic site. As described above, the characteristic time-dependent changes in blood vessel shape are caused by the progression of, for example, tumors and fluid leakage. It is also possible to detect changes over time in the meandering state of blood vessels, changes over time in blood vessel diameter, and the like as characteristic changes over time. In addition, the result of such processing can be used for evaluation of aptitude for OCT blood flow measurement.

Here, when the shift of the measurement path (see FIG. 3) is applied, the accuracy of comparison with the local angle distribution information and the time-dependent angle change information may decrease 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 over time in blood vessels, it is not appropriate to compare the tilt angle obtained by shifting the measurement path with the tilt angle obtained without shifting.

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

By using a known configuration for aligning the optical system of the device with the eye to be inspected, it is possible to detect the presence or absence of a shift in the measurement path and the amount of shift. For example, the alignment state (presence or absence of shift, shift amount) can be determined from the position of the feature point (pupil center, etc.) in the anterior segment image obtained by photographing the anterior segment of the eye to be inspected (by the front image acquisition unit 60). Can be detected. Alternatively, it is also possible to detect the reflected light of the luminous flux projected from the oblique direction with respect to the cornea to obtain the position of the apex of the cornea, and to detect the alignment state from this.

The evaluation result acquired by the evaluation processing unit 431 is used for setting the position (measurement position) where the 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 the 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 to be H rank are set as measurement positions. At this time, the position (1 or 2 or more) can be selected by ranking the position of 1 or more determined to be H rank. This ranking can be performed based on, for example, the value of the tilt angle at each position, or can be performed based on other information. Examples of other information include evaluation results based on local angle distribution information, evaluation results based on temporal angle change information, blood vessel thickness, blood vessel depth position, positional relationship with nearby blood vessels, and blood vessel type ( Arteries, veins, etc.), blood vessel bifurcation state, positional relationship with lesion, diagnosis name (confirmed diagnosis name, suspected diagnosis name, etc.), past measurement position, etc. It is also possible to refer to this information in other processing.

When there is no position determined to be H rank, for example, a measurement site can be set from the positions determined to be M rank. Alternatively, if there is no position determined to be H rank, or if there is neither a position determined to be H rank nor a site determined to be M rank, OCT angiography and acquisition of the blood vessel angle distribution may be performed again, or these It is possible to encourage them to do this again.

<Blood flow information generator 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 the 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 collecting unit 30 includes at least the data (first data) collected by repeatedly scanning the cross section of interest that intersects the blood vessel of interest, intersects the blood vessel of interest, and is different from the cross section of interest 1. The data (second data) obtained by scanning the above cross section (cross section in the vicinity of the cross section of interest) 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 in the vicinity thereof, which is acquired separately from the OCT blood flow measurement, can be used. As an example, it is possible to use the inclination angle (blood vessel angle distribution) obtained by the blood vessel angle distribution acquisition unit 42.

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

In OCT blood flow measurement, two types of scans (auxiliary scan and main scan) are performed on the fundus. Auxiliary scanning is performed to scan one or more cross sections (cross sections in the vicinity of the cross section of interest) different from the cross section of interest to collect second data. In a typical auxiliary scan, two or more cross sections intersecting the blood vessel of interest are scanned with the measurement light. The data obtained by the auxiliary scan is used to determine the tilt angle of the blood vessel of interest in the cross section of interest. On the other hand, this scan is performed to collect the first data by repeatedly scanning the cross section of interest intersecting the blood vessel of interest with the measurement light. The cross section on which the auxiliary scan is performed is placed in the vicinity of the cross section of interest. This scan is a Doppler measurement using OCT.

The target cross sections of the auxiliary scan and the main scan are oriented so as to be orthogonal to the traveling direction of the blood vessel of interest, for example. Further, the distance between the target cross section of the auxiliary scanning and the cross section of interest (distance between cross sections) is set in advance or is set for each inspection. 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 in or near the cross section of interest and the inspection accuracy. In addition, the user may set a desired distance between cross sections.

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 can be obtained. The execution time of this scan may be a preset constant time, or may be a preset time for each patient or each examination.

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

Further, the blood flow information generation unit 44 forms a tomographic image group representing a time-series change in the morphology of the cross section of interest based on the data collected by the main scan (repetitive scan) of the cross section of interest. This process is achieved, for example, by forming a tomographic image from the data collected for each scan iteration. 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 (additional average, moving average, etc.) of these tomographic images.

The process 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 technique. 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 showing the time-series change of the phase difference in the cross section of interest based on the data collected by the main scanning of the cross section of interest. The data used for this process 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 method of forming a phase image will be described. In a typical example, a phase image is obtained by calculating the phase difference between adjacent A-line complex signals (signals corresponding to adjacent scanning points). In other words, the phase image of this example is formed for each pixel of the tomographic image of the cross section of interest based on the time-series change of the pixel value (luminance value) of the pixel. For any pixel, the blood flow information generation unit 44 considers a graph of time-series changes in its luminance value. The blood flow information generation unit 44 obtains the phase difference Δφ between two time points t1 and t2 (t2 = t1 + Δt) separated by a predetermined time interval Δt in this graph. Then, this 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 at each of a large number of preset time points, a time-series change in the phase difference in the pixel can be obtained.

The phase image represents the value of the phase difference at each time point of each pixel as an image. This imaging process can be realized, for example, by expressing the value of the phase difference in display color or brightness. At this time, the color indicating that the phase has increased along the time series (for example, red) and the color indicating that the phase has decreased (for example, blue) can be different. In addition, the magnitude of the amount of change in phase can be expressed by the density of the display color. By adopting such an expression method, it is possible to present the direction and size of blood flow 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 can be obtained by sufficiently reducing the time interval Δt and ensuring the phase correlation. At this time, in scanning the measurement light, oversampling is executed in which the time interval Δt is set to a value less than the time corresponding to the resolution of the tomographic image.

The blood flow information generation unit 44 can execute, for example, a blood vessel region identification 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 identification process, the blood flow information generation unit 44 identifies the blood vessel region in the tomographic image corresponding to the blood vessel of interest. Further, the blood flow information generation unit 44 identifies the 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 blood vessel of interest in the cross section of interest 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 the cross sections and the specific result of 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. When the tilt angle acquired by the blood vessel angle distribution acquisition unit 42 is used for OCT blood flow measurement, it is not necessary to execute the tilt 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 scan (Doppler OCT) and the blood vessel inclination angle (or blood vessel angle distribution) calculated by the inclination angle calculation process. Blood flow information regarding the blood vessel of interest is generated based on the tilt angle obtained by the acquisition unit 42). As described above, the blood flow information generation process of a typical example includes a blood flow velocity calculation process, a blood vessel diameter calculation process, and a blood flow volume calculation process.

The blood flow information generation unit 44 can calculate the blood flow velocity in the cross section of interest of the blood flowing in the blood vessel of interest based on the time-series change of the phase difference obtained as the phase image. The value calculated by this process may be the blood flow velocity at a certain point in time, or may be a time-series change in the 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). Also, the time range in the latter is the entire or arbitrary part of the time taken to scan the cross section of interest.

When the blood flow velocity change information is obtained, the blood flow information generation unit 44 can calculate the statistical value of the blood flow velocity in the time range. The statistical values include mean value, standard deviation, variance, median value, maximum value, minimum value, maximum value, and minimum value. It is also possible to create a histogram of blood flow velocity values.

The blood flow information generation unit 44 can calculate the blood flow velocity by using the Doppler OCT method as described above. For example, the following relational expression is used to calculate 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: The angle (inclination angle) formed by the incident direction of the measurement light and the flow direction 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 tilt angle θ is the tilt angle calculation process or the 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 above relational expression.

In the blood vessel diameter calculation process, the blood flow information generation unit 44 calculates the diameter of the blood vessel of interest in the cross section of interest. Examples of this calculation method include a first calculation method using a frontal image of the fundus and a second calculation method using a tomographic image.

When the first calculation method is applied, the portion of the fundus including the position of the cross section of interest is photographed in advance. This fundus photography is performed by, for example, the front image acquisition unit 60. Alternatively, the frontal image of the fundus that has been acquired and saved in the past may be read out.

The blood flow information generation unit 44 determines the relationship between the scale on the image and the scale in the real space, such as the shooting angle of view (shooting magnification), the working distance, and the information of the eyeball optical system, based on various factors of the fundus. Set the scale in the front image. This scale represents the length in real space. As a specific example, this scale associates the spacing between adjacent pixels with the scale in real space (for example, the spacing between pixels = 10 μm). It is also possible to calculate in advance the relationship between various values of the above factors and the scale in the real space, and store information expressing this relationship in a table format or a graph format. In this case, the scale corresponding to the above 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 this scale and the pixels included in the blood vessel region. As a specific example, the blood flow information generation unit 44 can obtain the maximum value and the average value of the diameters of the blood vessel regions in various directions. Alternatively, the blood flow information generation unit 44 can approximate the contour of the blood vessel region to a circle or an ellipse, and obtain the diameter of the circle or the ellipse. Since the area of the blood vessel region can be determined (substantially) once the blood vessel diameter is determined, the area may be calculated instead of obtaining the blood vessel diameter.

The second calculation method will be described. In the second calculation method, a tomographic image of the fundus in the cross section of interest is used. This tomographic image may be a tomographic image based on this scan, or may be acquired 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 real space, such as working distance and information on the eyeball optics. The blood flow information generation unit 44 can obtain, for example, the distance 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 in 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 blood vessel of interest based on the calculation result of the blood flow velocity and the calculation result of the blood vessel diameter. An example of this process will be described below.

It is assumed that the blood flow in the blood vessel is Hagen-Poiseuille flow. Further, the blood vessel diameter is w, and the maximum value of blood flow velocity is 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 process and the maximum value Vm of the blood flow velocity obtained by the blood flow velocity calculation process into the above relational expression to obtain a blood flow rate. Q can be calculated.

<Operation unit 50>
The operation unit 50 is used for the user to input an instruction to the ophthalmologic imaging device 1. The operation unit 50 may include a known operation device used in an ophthalmic 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. Further, the operation unit 50 may include a touch panel. In this case, the control unit 10 can display the GUI for operating the ophthalmologic imaging device 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 optional. 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 an optical system of a fundus camera, an optical system of an SLO, 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 eye to be inspected from an external device. For example, the front image acquisition unit 60 may include a communication device for transmitting / 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, for example, the front image of the fundus of the eye to be inspected stored in the electronic medical record system or the image archiving system, using the patient ID, 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. The OCT front image includes a C mode image, a projection image, a shadow gram, and the like.

When a frontal image is formed by rendering the 3D dataset used to form the vessel-enhanced image, the vessel-enhanced image and the frontal image via a common 3D dataset (ie, a common 3D coordinate system). It is possible to register with. In general, registration between a blood vessel-enhanced image and a frontal image includes, for example, a process of detecting a feature site (optic disc, macula, blood vessel, lesion, laser scar, etc.) from both images and a feature site of both. It can be performed through the process of aligning both images with reference to.

<motion>
Some examples of actions that an exemplary ophthalmologic imaging device can perform will be described.

<First operation example>
In the first operation example, OCT blood flow measurement is performed at a measurement position set based on the blood vessel angle distribution obtained by using OCT angiography. The flow of processing executed in this example is shown in FIG. Preparatory processing such as input of patient ID, alignment of optical system with respect to the eye to be inspected, focus adjustment of optical system, adjustment of OCT optical path length, adjustment of fixation position, setting of OCT scan range, 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 eye to be examined 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: Form a blood vessel-enhanced image of the fundus)
The image forming unit 41 forms a three-dimensional blood vessel-enhanced image based on the three-dimensional data set collected in step S1.

(S3: Obtain the 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 emphasized image formed in step S2. The obtained blood vessel angle distribution is stored in, for example, the storage unit 20.

(S4: Set the measurement position)
The measurement position setting unit 43 sets the 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 one or more positions of the fundus as a 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 by using the result of this evaluation.

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

At this time, the collection control unit 11 controls the light source and the 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 at least repeatedly scanning the first cross section intersecting the blood vessel at the measurement position set in step S4. In addition to this, the data collection unit 30 can collect the second data by scanning one or more auxiliary cross sections intersecting the blood vessel.

The blood flow information generation unit 44 generates blood flow information regarding 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, the tilt angle represented by the blood vessel angle distribution (tilt angle at the measurement position, tilt angle in the vicinity of the measurement position, etc.) is used.

The control unit 10 can display the generated blood flow information on the display device 2, store it in the storage unit 20, and transmit it to an external device. In addition, the information obtained by OCT blood flow measurement (tomographic image, phase image, etc.) and / or the image obtained by OCT angiography (3D data set, blood vessel emphasized image, etc.) are also displayed in the same manner. It is possible to save, send, etc.

<Second operation example>
In the second operation example, the measurement position is recognized by the user by superimposing the image showing the measurement position (measurement position image) on the front image of the fundus. The flow of processing executed in this example is shown in FIG.

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

(S15: Acquire a frontal 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 photographs the fundus after step S14. This fundus photography is, for example, photography using infrared light. Typically, the latest frame of the infrared observation image (moving image) whose acquisition is started 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 of the eye by accessing an electronic medical record system or the like, or by rendering the three-dimensional data set collected in step S11. The timing of acquiring the front image may be arbitrary.

(S16: Specify the position in the front image corresponding to the measurement position)
The data processing unit 40 (and / or the display control unit 12 and 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, for example, as follows.

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 frontal image showing the morphology of the fundus.

Next, the data processing unit 40 performs registration between the projection image and the front image acquired in step S15. As a result, the position in the projection image and the position in the front image are associated with each other.

Here, the measurement position set in step S14 is set using the three-dimensional data set, and the 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.

The process for specifying the position in the front image corresponding to the measured image is not limited to this example. For example, the same processing result can be obtained by performing registration between the blood vessel-enhanced image formed in step S12 and the frontal image acquired in step S15.

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

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, for example, an image showing the position of the first cross section. Further, the measurement position image may include an image showing the position of the second cross section. Further, the measurement position image may include an image representing a region including a first cross section (and a second cross section). Further, the measurement position image may include an image showing a blood vessel (blood vessel of interest) that is symmetrical to the 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 executes 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). The 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, the front image G acquired by the fundus camera is overlaid with the measurement position image showing the position of the first cross section and the measurement position image showing the position of the second cross section.

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

These three linear images D1, D2, and D3 allow the user to grasp which blood vessel (attention blood vessel C) in the fundus the OCT blood flow measurement is performed on, and which of the attention blood vessels C. It is possible to grasp whether OCT blood flow measurement is performed at the position.

Further, 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 showing the position of the first cross section is displayed in the first color (for example, red), and the linear images D2 and D3 showing the positions of the 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 distinguishable manner.

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

(S21: Specify the blood vessel of interest)
In this example, the blood vessel of interest is first specified. The designation of the blood vessel of interest is performed manually or automatically.

When manually designating the blood vessel of interest, for example, the display control unit 12 displays a frontal image of the fundus of the eye to be inspected on the display device 2. Typically, the display control unit 12 transmits the front image acquired by the front image acquisition unit 60 by photographing the fundus, or the front image acquired by accessing the electronic medical record system or the like to the display device 2. indicate. The user specifies 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. The control unit 10 stores, for example, this front image and a position (position information of a blood vessel of interest) designated by the user in the storage unit 20.

When automatically designating a blood vessel of interest, for example, the control unit 10 accesses an electronic medical record system or the like to acquire information indicating a predetermined blood vessel in the fundus of the eye to be inspected. As an example, the control unit 10 acquires information indicating a blood vessel for which OCT blood flow measurement has been performed in the past. When the blood vessel to be measured for OCT blood flow is determined according to a predetermined factor (diagnosis name, etc.), the control unit 10 accesses the electronic medical record system or the like to obtain the diagnosis name, etc. of the eye to be inspected. Then, select the blood vessel of interest corresponding to this diagnosis name and the like. The control unit 10 stores information indicating an automatically designated blood vessel of interest in the storage unit 20.

As another example of the case of automatically designating the blood vessel of interest, the data processing unit 40 can specify the blood vessel of interest by analyzing an image (front image, OCT image, etc.) of the fundus of the eye to be inspected. This analysis process includes, for example, a process of comparing the morphology of blood vessels (meandering, thickness, etc.) with standard values. The control unit 10 stores information (and the above image) indicating the blood vessel of interest designated by the data processing unit 40 in the storage unit 20.

(S22: Collect a three-dimensional data set of the region containing the blood vessel of interest by fundus OCT)
The front image acquisition unit 60 acquires a front image by photographing the fundus of the eye to be inspected. The data processing unit 40 and the like register the front image with the image (front image, OCT image, etc.) stored in the storage unit 20 in step S21 to form an area in the front image corresponding to the blood vessel of interest. Can be identified. When the image is not stored in the storage unit 20 in step S21, for example, the data processing unit 40 or the like moves to the anatomical morphology (orientation, tissue arrangement, etc.) of the fundus or the position specified in step S21. Based on this, the region in the frontal image corresponding to the blood vessel of interest can be identified.

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

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

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

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

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

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

(S31: Collect 3D data set by fundus OCT)
Step S31 is executed in the same manner as step S1 of the first operation example.

(S32: Specify the blood vessel of interest)
The blood vessel of interest is designated manually or automatically.

When manually designating the blood vessel of interest, 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 specifies a desired blood vessel in the projection image displayed on the display device 2 by using the operation unit 50. The blood vessel of interest may be designated for the front image acquired by the front image acquisition unit 60 or the blood vessel-enhanced image based on the three-dimensional data set collected in step S31. Such processing can be executed in the same manner as in S21 of the third operation example. The case of automatically designating the blood vessel of interest can also be executed in the same manner as in S21 of the third operation example.

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

<Second Embodiment of Ophthalmologic Imaging Equipment>
Other exemplary embodiments of the ophthalmologic imaging apparatus will be described. In this embodiment, a measurement mode different from the above-mentioned blood vessel mode of interest will be described. The measurement mode of this embodiment is used to estimate the total blood flow in the fundus (whole blood flow mode).

To estimate total blood flow, it is necessary to distinguish between arteries and veins. This is because if this discrimination is not performed, the blood flow flowing into the fundus and the blood flow flowing out from the fundus will be counted in duplicate. FIG. 10 shows a configuration example of the ophthalmologic imaging apparatus according to the present embodiment.

The ophthalmologic imaging apparatus 1A is different from the ophthalmologic imaging apparatus 1 of the first embodiment in that the data processing unit 40 is provided with the classification processing unit 45. The same reference numerals are given to the same elements as those in the first embodiment. Unless otherwise specified, the elements of the ophthalmologic imaging apparatus 1A have the same configuration as that of the first embodiment and perform the same operation.

The classification processing unit 45 classifies a plurality of blood vessels depicted in the blood vessel-enhanced image formed by the image forming unit 41 into arteries and veins. Here, "classification" is not only a process of classifying a plurality of objects into two or more types (categories) according to a predetermined standard, but also a process of extracting one or more types from a plurality of objects according to a predetermined standard. Or, it shall include the process of identifying the target corresponding to one or more types among a plurality of targets according to a predetermined standard.

Therefore, the classification processing unit 45, for example, performs a process of classifying a plurality of blood vessels depicted in a blood vessel-enhanced image into an artery category and a vein category, and extracts a blood vessel corresponding to an artery (vein) from the plurality of blood vessels. The treatment, at least one of the treatments for identifying a blood vessel corresponding to an artery (vein) among a plurality of blood vessels may be feasible. It is not necessary to classify all blood vessels. For example, only blood vessels having a diameter equal to or larger than a predetermined threshold value can be classified.

An example of the processing executed by the classification processing unit 45 will be described. The classification processing unit 45 determines, for example, whether the blood vessels are arteries or veins for at least a part of each of the plurality of blood vessels depicted in the frontal image of the fundus acquired by the frontal image acquisition unit 60. .. This determination can be performed based on, for example, the pixel value of the front image, the crossed state of blood vessels, the blood column reflex, and the like (see JP-A-2007-319403, etc.). The classification processing unit 45 reflects the classification result using the front image on the blood vessel-enhanced image by, for example, registering the front image and the blood vessel-enhanced image. Thereby, a plurality of blood vessels depicted in the blood vessel-enhanced image can be classified into an arterial group and a vein group.

In another example, the classification processing unit 45 can also discriminate between arteries / veins based on the blood vessel distribution and the phase image obtained from the blood vessel emphasized image. Specifically, the classification processing unit 45 can first obtain the route of the blood vessel from the optic nerve head to a predetermined position based on the blood vessel-enhanced image. Next, the classification processing unit 45 can determine the blood flow direction of the blood vessel at the position based on this 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-enhanced image and the blood flow direction obtained from the phase image. As a result, a group of blood vessels classified into arteries (arterial group) and / or a group of blood vessels classified into veins (vein group) can be obtained. Since the blood vessel-enhanced image and the phase image are images created from the same three-dimensional data set, registration between them is unnecessary.

An example of an operation that can be executed by the ophthalmologic imaging 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 executed in the same manner as steps S1, S2 and S3 of the first operation example, respectively.

(S44: Classify multiple fundus blood vessels into arteries / veins)
The classification processing unit 45 classifies the plurality of fundus blood vessels depicted in the blood vessel-enhanced image formed in step S42 into arteries and veins. In this example, it is assumed that the 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: Set the measurement position of each artery (each artery))
The measurement position setting unit 43 sets the measurement positions of the blood vessels included in the arterial group extracted in step S44. This process is performed by applying the same process as in step S4 of the first operation example to each of the blood vessels included in this arterial group.

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

An example of the process of this step S46 will be described. First, the control unit 10 (or the data processing unit 40, etc.) assigns an order to the plurality of measurement positions set in step S45. For example, the order may be assigned clockwise or counterclockwise based on a predetermined direction (upper, lower, nasal side, ear side, etc.), or the order may be assigned in order from the measurement position closest to the predetermined part (optic disc, etc.). , It is possible to assign the order according to the morphology (thickness, etc.) of the blood vessel.

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

Under the control of the collection control unit 11, the data collection unit 30 controls so as to sequentially and repeatedly scan the plurality of first cross sections set for the arterial group in the above order. Here, the method of repetitive scanning for a 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 collecting unit 30 is sent to the blood flow information generating unit 44. If a second cross section is also set, that scan is also performed.

The blood flow information generation unit 44 sets the first data collected by repeated scanning of the first cross section for each of the plurality of first cross sections corresponding to the plurality of blood vessels included in the arterial group, and the inclination at the corresponding measurement position. The blood flow in this blood vessel is calculated based on the angle. This process is executed in the same manner as in the first embodiment. As a result, the blood flow rate of each of the plurality of blood vessels contained in the arterial group can be obtained.

The blood flow information generation unit 44 calculates the total blood flow rate based on a plurality of blood flow rates calculated for a plurality of blood vessels included in the arterial group (that is, a plurality of measurement positions set by the measurement position setting unit 43). .. 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 a plurality of blood flow rates based on a predetermined factor, or a process of correcting the value of the total blood flow rate based on a predetermined factor. .. For example, the value of blood flow can be corrected according to the morphology (thickness, meandering state, etc.) and position of the blood vessel. Further, when a blood vessel having a diameter smaller than the predetermined threshold value is excluded from the calculation, a correction may be made to add the excluded blood flow rate.

In another example, the blood flow information generation unit 44 can obtain the total blood flow rate for arteries and the total blood flow rate for veins, and can calculate statistical values 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 flows, and calculate statistical values based on these.

<Third Embodiment of Ophthalmologic Imaging Equipment>
Other exemplary embodiments of the ophthalmologic imaging apparatus will be described. In the present embodiment, by detecting the size of the pupil of the eye to be inspected and correcting the angle condition information, it is possible to evaluate the inclination angle and set the measurement position according to each eye to be inspected. A configuration example of such an ophthalmologic imaging apparatus is shown in FIG.

The ophthalmologic imaging apparatus 1B is different from the ophthalmologic imaging apparatus 1 of the first embodiment in that the data processing unit 40 is provided with the pupil size information acquisition unit 46. The same reference numerals are given to the same elements as those in the first embodiment. Unless otherwise specified, the elements of the ophthalmologic imaging apparatus 1B have the same configuration as that of 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 inspected. The pupil size is expressed, for example, as 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 pupil size information, for example, by analyzing the anterior segment image of the eye to be inspected. As an example in this case, the front image acquisition unit 60 acquires a front image (anterior eye portion image) of the anterior segment of the eye to be inspected. 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 the three-dimensional data set collected by the anterior segment OCT as the anterior segment image. The pupil size information acquisition unit 46 can specify, for example, a pupil region based on the pixel value of the anterior segment image, approximate the outline of the pupil region to a circle or an ellipse, and obtain the diameter of the circle or the ellipse. Since the area of the pupil region can be determined (substantially) once the pupil diameter is determined, 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 inspected from an external device (electronic medical record system or the like) via a communication line.

The evaluation processing unit 431 changes at least one of 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, the angle condition of M rank capable of correcting the inclination angle to the preferable range “75 to 80 degrees” by shifting the measurement light as shown in FIG. 3 and the like, and the angle condition of M rank. The N rank angle condition that cannot be corrected is changed.

In the process of changing the angle condition, the above-mentioned relational expression Δθ = arctan (d / T) is referred to. Here, as shown in FIG. 3, Δθ is the angle formed by the measurement path LS0 and the measurement path LS1 at the fundus, d is the shift distance of the measurement path LS1 with respect to the measurement path LS0, and T is the eye to be inspected. It is the length of the measured optical path LS0 in. The pupil size is a constraint condition for the shift distance d of the measurement path, and the larger the pupil, the larger the shift distance d. Typically, half the pupil diameter (ie, the radius of the pupil) can be set to the maximum 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 when the correction of the angle condition information is added to the first operation example of the first embodiment, but the same applies to the case where the correction of the angle condition information is added to another operation example or another embodiment. Is.

(S51: Acquire pupil size information)
First, the pupil size information acquisition unit 46 and the like acquire the pupil size information of the eye to be inspected.

(S52: Change the 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, it may not be necessary to change the angle condition information. For example, when the angle condition information is created for the pupil size in the predetermined range and the value indicated by the pupil size information obtained in step S51 is included in the predetermined range, it is not necessary to change the angle condition information.

(S53 to 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: Set the measurement position 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 executes 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 Ophthalmologic Imaging Equipment>
Other exemplary embodiments of the ophthalmologic imaging apparatus will be described. In the present embodiment, the pupil diameter at the time of applying the mydriatic agent is estimated from the size of the pupil of the eye to be inspected in the state where the mydriatic agent is not applied, and the angle condition information is corrected. This makes it possible to simulate evaluation assuming the application of a mydriatic agent. FIG. 14 shows a configuration example of such an ophthalmologic imaging apparatus.

The ophthalmologic imaging apparatus 1C is different from the ophthalmologic imaging apparatus 1B of the third embodiment in that the data processing unit 40 is provided with the pupil size estimation unit 47. The same reference numerals are given to the same elements as those in the third embodiment. Unless otherwise specified, the elements of the ophthalmologic imaging apparatus 1C have the same configuration as that of 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 inspected. In the present embodiment, the pupil size in the state where the mydriatic agent is not applied (that is, the state where the mydriasis is not applied) is acquired. For example, by analyzing the anterior segment image obtained by photographing the anterior segment of the eye to be inspected to which the mydriatic agent is not applied, the pupil size information in the state where the mydriatic agent is not applied can be obtained. Can be obtained. Further, such pupil size information may be acquired from an external device (electronic medical record system or the like) via a communication line.

The pupil size estimation unit 47 estimates the size of the pupil of the eye to be inspected 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 made, for example, with reference to one of the following: standard values for changes in pupil size due to mydriasis (clinically obtained statistics, etc.); mydriasis in the past for the eye being examined. The amount of change in pupil size when the agent is applied.

Such reference information can be prepared for each of the two or more types of mydriatic agents. In addition, reference information can be prepared step by step according to the value of the pupil size at the time of non-mydriasis. In addition, a plurality of reference information can be prepared according to arbitrary factors such as a diagnosis name (confirmed diagnosis name, suspected diagnosis name, etc.), administered drug, medical history, drug history, age, gender, and the like. Information on such factors is obtained from, for example, an electronic medical record system or the like.

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 carried out 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 pupil size estimation is added to the operation example of the third embodiment, but the same applies to the case where the pupil size estimation is added to the other operation examples or other embodiments.

(S61: Acquire pupil size information)
First, the pupil size information acquisition unit 46 and the like acquire the pupil size information of the eye to be inspected.

(S62: Estimate pupil size at 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 above-mentioned reference information) acquired in step S61.

(S63: Change the 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. It is not necessary to change the angle condition information depending on the value indicated by the estimated pupil size.

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

(S67: Set the measurement position 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 executes 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 / effect>
The operation and effect of an exemplary ophthalmologic imaging device will be described.

An exemplary ophthalmologic imaging device (1, 1A, 1B, 1C) includes a data collection unit (30), a blood vessel-enhanced image forming unit (image forming unit 41), a blood vessel angle distribution acquisition unit (42), and a measurement position. It includes a setting unit (43), a collection control unit (11), and a blood flow information generation unit (44).

The data collection unit can collect a three-dimensional data set of the fundus of the eye to be inspected by using OCT. The blood vessel-enhanced image forming unit can form a blood vessel-enhanced image based on this three-dimensional data set. Based on this blood vessel-enhanced image, the blood vessel angle distribution acquisition unit can obtain a blood vessel angle distribution representing the inclination angle of blood vessels at one or more positions of the fundus. The measurement position setting unit can set the measurement position to be the target of OCT blood flow measurement based on this blood vessel angle distribution. The collection control unit can control the data collection unit so as to repeatedly scan the first cross section intersecting the blood vessel at this measurement position. The blood flow information generation unit generates blood flow information representing the blood flow state in this 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 this measurement position. Can be done.

In the embodiment, the collection control unit can control the data collection unit so as to scan one or more second cross sections intersecting 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 this blood vessel at this measurement position based on the second data collected by scanning the second cross section. Further, the blood flow information generation unit can generate blood flow information based on the calculated inclination angle and the first data.

An exemplary ophthalmologic imaging device (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 (observation image, photographed image, etc.) of the fundus. The display control unit can 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 on the display means (display device 2).

In embodiments, 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 blood vessel mode of interest in which the measurement position of a specific blood vessel is searched and blood flow is measured. In an exemplary ophthalmologic imaging device (1) for realizing the blood vessel mode of interest, when a blood vessel in the fundus is specified in advance, the blood vessel angle distribution acquisition unit receives a blood vessel angle distribution representing an inclination angle at a plurality of positions of the blood vessel. Can be sought. Further, the measurement position setting unit can set the measurement position of the blood vessel based on the blood vessel angle distribution.

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

Another example of the measurement mode is the total blood flow mode for estimating the total blood flow in the fundus. An exemplary ophthalmologic imaging apparatus (1A) for achieving a 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-enhanced image into arteries and veins. The measurement position setting unit sets the measurement positions of the blood vessels included in this blood vessel group for at least one of the blood vessel group classified as an artery (arterial group) and the blood vessel group classified as a vein (vein group). Can be done.

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

In the embodiment, the measurement position setting unit may include an evaluation processing unit (431). The evaluation processing unit can evaluate the suitability as a target position for OCT blood flow measurement based on the inclination angle at each of the 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 by the blood vessel angle distribution with the angle condition information (21a) representing the one or more angle conditions, thereby performing OCT blood flow. It is possible to evaluate the suitability as a measurement target position.

An 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 inspected. 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 the suitability as a target position for OCT blood flow measurement by using the angle condition information in which one or more angle conditions are changed.

An 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 inspected in a state where the mydriatic agent is not applied. The pupil size estimation unit can estimate the size of the pupil of the eye to be inspected 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 the suitability as a target position for OCT blood flow measurement by using the 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, the blood vessel angle distribution is automatically obtained based on the (three-dimensional) blood vessel emphasized image obtained by OCT angiography, and the measurement position for OCT blood flow measurement based on this blood vessel angle distribution. Can be automatically set and OCT blood flow measurement can be performed at this measurement position. Therefore, it is possible to search for a position where the direction of the blood vessel is suitable and automatically perform OCT blood flow measurement. Therefore, it is possible to reduce the burden on the examiner and the subject in the OCT blood flow measurement.

The actions and effects of the embodiments are not limited to these, and the actions and effects provided by each of the items described as the embodiments and the actions and effects provided by the combination of a plurality of items should also be considered. In addition, any of the above-mentioned 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 only an example for preferably carrying out the present invention. Therefore, any modification (omission, substitution, addition, etc.) within the scope of the gist of the present invention can be appropriately applied.

1, 1A, 1B, 1C Ophthalmic imaging device 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 formation 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 Puppy size information acquisition unit 47 Puppy size information acquisition unit 50 Operation unit 60 Front image acquisition unit

Claims (4)

A data collection unit that collects a three-dimensional data set of the fundus of the eye to be inspected using optical coherence tomography (OCT),
A blood vessel-enhanced image forming unit that forms a blood vessel-enhanced image based on the three-dimensional data set by OCT angiography,
Based on the blood vessel-enhanced image, a blood vessel angle distribution acquisition unit for obtaining a blood vessel angle distribution representing a blood vessel inclination angle with respect to the A scan direction at one or more positions of the fundus, and a blood vessel angle distribution acquisition unit.
A measurement position setting unit that sets a measurement position to be measured for OCT blood flow based on the blood vessel angle distribution, and a measurement position setting unit.
A collection control unit that controls the data collection unit so as to repeatedly scan the first cross section intersecting the blood vessel at the measurement position.
Based on the first data collected by the repeated scanning of the first cross section and the inclination angle of the blood vessel with respect to the A scan direction at the measurement position, blood flow information representing the blood flow state in the blood vessel is obtained. and the blood flow information generation unit for generating,
A classification processing unit that classifies a plurality of blood vessels depicted in the blood vessel-enhanced image into arteries and veins.
With
The measurement position setting unit sets the measurement positions of the blood vessels included in the blood vessel group for at least one of the blood vessel group classified into arteries and the blood vessel group classified into veins.
An ophthalmologic imaging device characterized by this. The collection control unit controls the data collection unit so as 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, the blood flow rate in the blood vessel is based on the first data collected by the repeated scanning of the first cross section and the inclination angle with respect to the A scan direction at the measurement position. Is calculated and
The ophthalmologic imaging apparatus according to claim 1 , wherein the total blood flow rate is calculated based on the plurality of blood flow rates calculated for the plurality of measurement positions. A data collection unit that collects a three-dimensional data set of the fundus of the eye to be inspected using optical coherence tomography (OCT),
A blood vessel-enhanced image forming unit that forms a blood vessel-enhanced image based on the three-dimensional data set by OCT angiography,
Based on the blood vessel-enhanced image, a blood vessel angle distribution acquisition unit for obtaining a blood vessel angle distribution representing a blood vessel inclination angle with respect to the A scan direction at one or more positions of the fundus, and a blood vessel angle distribution acquisition unit.
A measurement position setting unit that sets a measurement position to be measured for OCT blood flow based on the blood vessel angle distribution, and a measurement position setting unit.
A collection control unit that controls the data collection unit so as to repeatedly scan the first cross section intersecting the blood vessel at the measurement position.
Based on the first data collected by the repeated scanning of the first cross section and the inclination angle of the blood vessel with respect to the A scan direction at the measurement position, blood flow information representing the blood flow state in the blood vessel is obtained. and a blood flow information generating unit that generates,
The measurement position setting unit
It includes an evaluation processing unit that evaluates suitability as a target position for OCT blood flow measurement based on an inclination angle based on the A scan direction at each of the one or more positions.
The measurement position is set based on the evaluation result obtained by the evaluation processing unit, and the measurement position is set.
The evaluation processing unit evaluates the aptitude by comparing the inclination angle with respect to the A scan direction at each of the one or more positions and the angle condition information representing the one or more angle conditions.
A pupil size information acquisition unit for acquiring pupil size information indicating the size of the pupil of the eye to be inspected is further provided.
The evaluation processing unit changes at least one of the one or more angle conditions based on the pupil size information.
An ophthalmologic imaging device characterized by this. The pupil size information acquisition unit acquires pupil size information representing the size of the pupil of the eye to be inspected in a state where the mydriatic agent is not applied.
A pupil size estimation unit for estimating the size of the pupil of the eye to be inspected in a state where the mydriatic agent is applied based on the pupil size information is provided.
The ophthalmologic imaging apparatus according to claim 3 , wherein the evaluation processing unit changes at least one of the above-mentioned one or more angle conditions based on the pupil size estimated by the pupil size estimation unit.

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