JP2024096393A - Ophthalmology information processing device - Google Patents

Abstract

A novel display mode for eye information is provided.
[Solution] A data input unit of an ophthalmologic information processing device of an embodiment inputs first OCT data constructed by a first ophthalmologic imaging device applying an OCT scan to a predetermined cross section of the fundus, and second OCT data constructed by a second ophthalmologic imaging device different from the first ophthalmologic imaging device applying OCT blood flow measurement to a blood vessel passing through the cross section. A display processing unit causes a display unit to display a composite image of the B-scan image and the blood flow state image by combining a blood flow state image in which the magnitude of the blood flow velocity of the blood vessel is expressed in color based on the second OCT data with a cross-sectional area of the blood vessel in a B-scan image of the cross section based on the first OCT data.
[Selected Figure] Figure 6

Description

The embodiment relates to an ophthalmology information processing device.

Diagnostic imaging plays an important role in the field of ophthalmology. In recent years, the use of optical coherence tomography (OCT) has been increasing. OCT is now being used not only to obtain B-scan images and 3D images of the examinee's eye, but also to obtain en-face images such as C-scan images and shadowgrams.

In addition, it is also possible to obtain images that highlight specific parts of the examinee's eye, and to obtain functional information. For example, based on the time series data collected by OCT, it is possible to construct a B-scan image or a frontal image (called a vascular-highlighted image, angiogram, etc.) in which the fundus blood vessels are highlighted. This technique is called OCT angiography, etc. In addition, it is possible to obtain information about blood flow based on the phase information of the time series data collected by OCT. This technique is called OCT blood flow measurement, etc.

JP 2015-515894 A JP 2013-184018 A

The purpose of the embodiment is to provide a new way of displaying eye information.

The ophthalmic information processing device of the embodiment includes a data input unit and a display processing unit. The data input unit inputs first image data of a subject's eye constructed by a first ophthalmic imaging device and second image data of the subject's eye constructed by a second ophthalmic imaging device different from the first ophthalmic imaging device. Composite information of a first image based on the first image data and a second image based on the second image data is displayed on a display means.

According to the embodiment, it is possible to provide a new display format for eye information.

1 is a schematic diagram illustrating an example of a configuration of an ophthalmologic imaging apparatus according to an exemplary embodiment. 4 is a schematic diagram for explaining an example of processing executed by an ophthalmologic imaging apparatus according to an exemplary embodiment; FIG. 10 is a flowchart illustrating an example of an operation of an ophthalmologic imaging apparatus according to an exemplary embodiment. 4 is a schematic diagram for explaining an example of processing executed by an ophthalmologic imaging apparatus according to an exemplary embodiment; FIG. 4 is a schematic diagram for explaining an example of processing executed by an ophthalmologic imaging apparatus according to an exemplary embodiment; FIG. 4 is a schematic diagram for explaining an example of processing executed by an ophthalmologic imaging apparatus according to an exemplary embodiment; FIG. FIG. 1 is a schematic diagram illustrating an example of a configuration of an ophthalmological information processing apparatus according to an exemplary embodiment.

Exemplary embodiments of the present invention will be described with reference to the drawings. Any known technology, including the disclosures of documents cited in this specification, may be combined with the embodiments.

The ophthalmic information processing device and ophthalmic imaging device according to the embodiment have a function of displaying various information based on data acquired by applying OCT to the fundus of the subject's eye. The ophthalmic information processing device according to the embodiment receives data acquired by applying OCT to the fundus of the subject's eye by a separately provided OCT device, for example, and displays various information based on this data. On the other hand, the ophthalmic imaging device according to the embodiment acquires data by applying OCT to the fundus of the subject's eye, and displays various information based on this data.

Data acquired by applying OCT to the fundus of a test eye (fundus OCT data) may be in any form. For example, the fundus OCT data may include any one or more of the following (1) to (5):
(1) Data collected by OCT scan of the fundus (raw data)
(2) Image data obtained by processing raw data. (3) Intermediate data obtained during a series of processes for generating image data from raw data. (4) Blood flow data obtained by processing raw data. (5) Intermediate data obtained during a series of processes for generating blood flow data from raw data.

Note that the types of fundus OCT data are not limited to these. Furthermore, the embodiment can process various information associated with the fundus OCT data. Examples of such information include subject identification information, subject eye identification information, identification information indicating whether the subject eye is the left eye or the right eye, the date and time of shooting, shooting conditions, etc.

The ophthalmic information processing device and ophthalmic imaging device according to the embodiment include a processor that executes data display processing. The ophthalmic information processing device according to the embodiment may further include a processor that processes raw data and intermediate data. The ophthalmic imaging device according to the embodiment further includes an optical system, a drive system, a control system, and a data processing system for performing OCT.

The ophthalmic imaging device of the embodiment is configured to be able to perform, for example, Fourier domain OCT. Fourier domain OCT includes spectral domain OCT and swept source OCT. Spectral domain OCT is a method of acquiring the spectrum of interference light in a spatial division manner using a broadband low-coherence light source and a spectrometer, and constructing an image by Fourier transforming it. Swept source OCT is a method of acquiring the spectrum of interference light in a time division manner using a wavelength swept light source (a wavelength tunable light source) and a photodetector (such as a balanced photodiode), and constructing an image by Fourier transforming it. The OCT method is not limited to Fourier domain OCT, and may be time domain OCT or unfath OCT.

The ophthalmic information processing device and ophthalmic imaging device according to the embodiments may include a modality (e.g., a modality other than OCT) for imaging the eye and/or other parts. Typical examples include a fundus camera, a scanning laser ophthalmoscope (SLO), a slit lamp microscope, and an ophthalmic surgical microscope. In addition, the ophthalmic information processing device and ophthalmic imaging device according to the embodiments may include a configuration for measuring characteristics of the eye and/or other parts, and a configuration for performing an examination.

The data processing functions (computational functions, image processing functions, control functions, etc.) in the ophthalmic information processing device and ophthalmic imaging device according to the embodiment are realized by, for example, hardware such as a processor or storage device working in cooperation with software such as a computation program, an image processing program, or a control program. Note that part of the hardware may be provided in an external device capable of communicating with the ophthalmic information processing device or ophthalmic imaging device according to the embodiment. Also, at least part of the software may be pre-stored in the ophthalmic information processing device or ophthalmic imaging device according to the embodiment and/or pre-stored in the external device.

Ophthalmic imaging equipment
<composition>
An ophthalmic imaging apparatus according to an exemplary embodiment will now be described. An example of the configuration of the ophthalmic imaging apparatus of this embodiment is shown in Fig. 1. The ophthalmic imaging apparatus 1 collects fundus data using OCT, generates fundus morphological images and fundus blood flow data based on the collected data, and displays various information based on these.

Here, the fundus morphological image is an image that represents the morphology of the fundus. In this embodiment, the fundus morphological image is an image that represents at least the fundus blood vessels (retinal blood vessels, choroidal blood vessels, etc.) in a visually identifiable manner. Examples of fundus morphological images include B-scan images, C-scan images, projection images, shadowgrams, phase images, and vascular enhancement images. Fundus blood flow data is data that represents the blood flow state (blood flow dynamics) in the fundus blood vessels. Examples of fundus blood flow data include the direction of blood flow, blood flow velocity, time series changes in blood flow velocity, blood flow rate, blood flow rate per unit time, time series changes in blood flow rate per unit time, and total blood flow rate.

In this embodiment, both morphological images and blood flow data are formed based on data obtained by applying OCT blood flow measurement to the fundus. Note that an OCT scan (e.g., B-scan, 3D scan) for obtaining a morphological image and an OCT scan (OCT blood flow measurement) for obtaining blood flow data may be performed separately. In addition, an OCT scan may be performed to obtain data other than the above. For example, an OCT angiogram may be performed.

A part of the data used to display the information may be acquired by another device. For example, one of the fundus morphological image and the fundus blood flow data may be acquired by another device. Alternatively, the other device may perform OCT angiography to acquire a vascular enhancement image. The data acquired by the other device is input to the ophthalmologic imaging device according to the embodiment.

The ophthalmic imaging device 1 can display various information such as fundus morphological images, blood flow information, and vascular enhancement images on the display device 2. The display device 2 may be a part of the ophthalmic imaging device 1, or may be an external device connected to the ophthalmic imaging device 1. In addition, the ophthalmic imaging device 1 can send various information to a computer, a storage device, an ophthalmic device, etc.

The ophthalmologic imaging device 1 includes a control unit 10, a memory unit 20, a data acquisition unit 30, an operation unit 50, and a front image acquisition unit 60. The control unit 10 includes a scan control unit 11 and a display control unit 12. The data acquisition unit 30 includes an OCT scanner 31, an image formation unit 32, and a blood flow data generation unit 33.

<Control Unit 10>
The control unit 10 controls each unit of the ophthalmologic imaging apparatus 1. The control unit 10 includes a processor. The "processor" refers to a circuit such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), or a programmable logic device (e.g., an SPLD (Simple Programmable Logic Device), a CPLD (Complex Programmable Logic Device), or an FPGA (Field Programmable Gate Array)). The control unit 10 can realize the functions according to the embodiment by, for example, reading and executing a program stored in a memory circuit or a storage device (the memory unit 20, an external device, etc.).

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

<Scan control unit 11>
The scan control unit 11 controls the OCT scanner 31. For example, the scan control unit 11 controls various elements included in the OCT scanner 31, such as control of a light source, control of an optical scanner, change of an optical path length of a measurement light and/or a reference light, polarization adjustment, light amount adjustment, focus adjustment, change of a fixation position, etc. Some examples of processes that can be executed by the scan control unit 11 will be described later.

<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 data stored in the storage unit 20.

The display control unit 12 can perform processing (generation, processing, synthesis, etc.) related to the information displayed on the display device 2. Such processing may be performed by cooperation between the display control unit 12 and other elements (other elements of the control unit 10, the data acquisition unit 30, etc.).

<Memory unit 20>
Various data are stored in the storage unit 20. In this example, OCT data 21 is stored in the storage unit 20. Note that at least a part of the OCT data may be stored in an external storage device and provided to the ophthalmic imaging apparatus 1 upon request. The storage unit 20 includes a storage device such as a hard disk drive or a semiconductor memory.

<OCT data 21>
The OCT data 21 includes any one or more of the above-mentioned fundus OCT data (1) to (5). Typically, the ophthalmologic imaging apparatus 1 generates morphological images and blood flow data from raw data collected by an OCT scan of the fundus, and stores the OCT data 21 including these in the storage unit 20. In other words, in a typical example, the OCT data 21 includes the above-mentioned fundus OCT data (2) and (4).

<Data Acquisition Unit 30>
The data acquisition unit 30 applies OCT to the fundus of the subject's eye to acquire data (e.g., at least a part of the OCT data 21 stored in the storage unit 20). As described above, the data acquisition unit 30 includes an OCT scanner 31, an image formation unit 32, and a blood flow data generation unit 33. The image formation unit 32 includes a processor that executes an image formation program. The blood flow data generation unit 33 includes a processor that executes a blood flow data generation program.

<OCT Scanner 31>
The OCT scanner 31 performs an OCT scan of the fundus under the control of the scan controller 11. As a result, data (raw data) of the fundus is collected. The OCT scanner 31 includes a configuration for performing optical interference measurement using, for example, spectral domain OCT or swept source OCT. The OCT scanner 31 includes an OCT optical system, a drive system, a data acquisition system (DAQ), a control system, and the like, as in the conventional case.

The OCT optical system includes, for example, an interference optical system, an optical scanner, and an optical detector. The interference optical system splits the light output from the light source into measurement light and reference light, projects the measurement light onto the fundus, and generates interference light by superimposing the return light of the measurement light from the fundus on the reference light. The optical scanner includes a galvano scanner or the like, and deflects the measurement light. This moves the projection position of the measurement light on the fundus. The optical detector detects the interference light (spectrum) generated by the interference optical system.

The drive system moves and operates the elements included in the OCT optical system. The data collection system collects the detection results sequentially obtained by the OCT optical system. The control system controls the OCT optical system, drive system, data collection system, etc. under the control of the scan control unit 11 (or other elements of the control unit 10).

In OCT blood flow measurement, the OCT scanner 31 repeatedly scans a cross section that intersects with a blood vessel at a preset measurement position to collect data. In other words, the OCT scanner 31 repeatedly scans a cross section of interest that intersects with a blood vessel of interest to collect data. The scan mode at this time is, for example, a line scan (B scan). This line scan is executed repeatedly at a predetermined frequency, for example. The data collected by such repeated scanning is sent to the image forming unit 32.

In OCT blood flow measurement, the OCT scanner 31 further performs a scan to determine 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 with the blood vessel of interest. Here, the two cross sections can be positioned near the cross section of interest.

One of the two cross sections used to calculate the inclination angle of the blood vessel of interest may be the cross section of interest itself. The other cross section is set in the vicinity of the cross section of interest. In this case, data obtained by repeatedly scanning the cross section of interest described above can be used to calculate the inclination angle.

In summary, typically, the scans performed in OCT blood flow measurement may be a combination of repeated scans of a cross section of interest and scans of two other cross sections, or a combination of repeated scans of a cross section of interest and scans of one other cross section.

The manner of scanning to determine 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 scanning). As another example, a cross section that intersects with the cross section of interest and runs along the blood vessel of interest can be scanned. OCT blood flow measurement will be described in detail in the explanation of the blood flow data generating unit 33.

When performing OCT angiography, the OCT scanner 31 scans a three-dimensional region of the fundus. The scan mode at this time is, for example, raster scan (three-dimensional scan). This raster scan is performed, for example, to scan each of a plurality of B-sections (B-scan planes) a predetermined number of times (for example, four times each). In other words, this raster scan is performed to scan a plurality of B-sections sequentially a predetermined number of times, or to scan according to a predetermined sequence. The three-dimensional data set collected by the OCT scanner 31 is sent to the image forming unit 32.

The types of scanning that the OCT scanner 31 can perform are not limited to those described above. For example, the OCT scanner 31 can perform line scanning, circle scanning, radial scanning, three-dimensional scanning, and the like as OCT scanning for obtaining morphological images.

<Image forming unit 32>
The image forming unit 32 forms an OCT image based on the data collected by the OCT scanner 31. For example, in OCT blood flow measurement, the image forming unit 32 forms a plurality of cross-sectional images (B-scan images) for each B-section based on the three-dimensional data set collected by the OCT scanner 31. The image forming process at this time includes, for example, noise removal (noise reduction), filtering, fast Fourier transform (FFT), and the like, similar to conventional OCT technology.

The image forming unit 32 can construct stack data by embedding these cross-sectional images in a single three-dimensional coordinate system. In this stack data, a number of cross-sectional images corresponding to the number of scan repetitions is assigned to each B-section. Furthermore, the image forming unit 32 can form volume data (voxel data) by performing interpolation processing, etc. on this stack data. In this volume data, a number of voxel groups corresponding to the number of scan repetitions is assigned to a position corresponding to each B-section.

The image forming unit 32 can generate B-scan images (longitudinal cross-sectional images, axial cross-sectional images), C-scan images (transverse cross-sectional images, horizontal cross-sectional images), projection images, shadowgrams, etc. by rendering the stack data or volume data.

Images of any plane, such as B-scan or C-scan images, can be generated by selecting pixels (voxels) on a specified plane from a 3D data set. Alternatively, images of any plane can be generated by projecting slices of a predefined thickness in the thickness direction.

A projection image is formed by projecting stack data or volume data in a specified direction (Z direction, depth direction, A-scan direction). A shadowgram is formed by projecting a portion of stack data or volume data (e.g. partial data corresponding to a specific layer) in a specified direction. Fundus images viewed from the cornea side of the test eye, such as C-scan images, projection images, and shadowgrams, are called frontal images.

In addition to rendering, the image forming unit 32 can perform various types of image processing. For example, it can perform segmentation to determine specific tissues or tissue boundaries, and size analysis to determine tissue size (layer thickness, volume, etc.). When a specific layer (or a specific layer boundary) is determined by segmentation, it is possible to reconstruct a B-scan image or a frontal image so that the specific layer is flat. Such an image is called a flattened image.

The image forming unit 32 can form a vascular emphasis image. A vascular emphasis image is an image in which an image region corresponding to blood vessels (vascular region) is identified by analyzing OCT data, and the representation of this vascular region is changed to emphasize it. To identify the vascular region, multiple sets of OCT data obtained by repeatedly scanning substantially the same area of the subject's eye are used.

A vascular enhancement image represents, for example, the distribution of blood vessels in a three-dimensional region of the fundus scanned by OCT (i.e., the three-dimensional distribution of blood vessels). There are several types of techniques for forming a vascular enhancement image. A typical technique will be described. This process uses a three-dimensional data set that includes multiple B-scan images arranged in time series for each B-section by repeatedly scanning each of multiple B-sections of the subject's eye. Fixation and tracking are techniques for repeatedly scanning substantially the same B-section.

In the process of forming a vascular enhancement image, first, multiple B-scan images are aligned for each B-section. This alignment is performed, for example, using a known image matching technique. As a typical example, it is possible to extract characteristic regions in each B-scan image and align the multiple B-scan images by aligning the extracted characteristic regions.

Next, a process is performed to identify image regions that have changed between the aligned B-scan images. This process includes, for example, a process of determining the difference between different B-scan images. Each B-scan image is luminance image data that represents the morphology of the subject's eye, and image regions that correspond to areas other than blood vessels are considered to be substantially unchanged. On the other hand, considering that the backscattering that contributes to the interference signal changes randomly due to blood flow, image regions in which changes have occurred between the aligned B-scan images (for example, pixels where the difference is not zero, or pixels where the difference is equal to or greater than a predetermined threshold) can be estimated to be vascular regions.

The image region identified in this way is assigned information indicating that it is a vascular region. By performing the above process on multiple B-sections, a vascular region distributed three-dimensionally can be obtained. By rendering such a 3D vascular-enhanced image, a frontal image showing the vascular distribution, an image of any section, a shadowgram of any range, etc. can be generated.

The process of forming a vascular-enhanced image is not limited to this. For example, it is possible to identify vascular regions using a conventional method that utilizes Doppler OCT, or to identify vascular regions using a conventional image processing method. In addition, it is possible to identify vascular regions for each region by using different methods depending on the region. For example, the vascular region of the retina can be identified using the typical method described above or a Doppler OCT method, and the vascular region of the choroid can be identified using an image processing method.

<Blood flow data generating unit 33>
The blood flow data generating unit 33 operates in the OCT blood flow measurement. The blood flow data generating unit 33 generates blood flow data representing the blood flow state in the blood vessel of interest based on the image of the cross section of interest formed by the image forming unit 32 based on the data collected by the OCT scanner 31 in the OCT blood flow measurement and the inclination angle of the blood vessel of interest in the cross section of interest.

The data collected by the OCT scanner 31 in OCT blood flow measurement includes data (first data) collected by repeatedly scanning a cross section of interest that intersects with the blood vessel of interest, and data (second data) obtained by scanning one or more cross sections (cross sections near the cross section of interest) that intersect with the blood vessel of interest and are different from the cross section of interest. Note that instead of the second data, for example, the inclination angle of the blood vessel of interest at or near the cross section of interest, which is obtained separately from the OCT blood flow measurement, can be used. As an example, it is possible to use the inclination angle obtained from a vascular enhancement image obtained by OCT angiography.

The image forming unit 32 forms a morphological image and a phase image of the fundus based on the data collected by the OCT scanner 31 during OCT blood flow measurement. The morphological image and phase image obtained by OCT blood flow measurement correspond to the same cross section. Typically, a morphological image and a phase image corresponding to the cross section of interest (cross section B) are obtained.

As described above, in a typical OCT blood flow measurement, two types of scans (auxiliary scan and main scan) are performed on the fundus. The auxiliary scan is performed to collect second data by scanning one or more cross sections (cross sections near the cross section of interest) different from the cross section of interest. In a typical auxiliary scan, two or more cross sections that intersect the blood vessel of interest are scanned with measurement light. The data acquired by the auxiliary scan is used to determine the inclination angle of the blood vessel of interest in the cross section of interest. On the other hand, the main scan is performed to collect first data by repeatedly scanning the cross section of interest that intersects the blood vessel of interest with measurement light. The cross section on which the auxiliary scan is performed is located near the cross section of interest. The main scan is a Doppler measurement using OCT.

The target cross sections of the auxiliary scan and the main scan are oriented, for example, perpendicular to the running direction of the blood vessel of interest. The distance between the target cross section of the auxiliary scan and the cross section of interest (cross section distance) is set in advance or set for each examination. As an example of the latter, the cross section distance can be set based on predetermined factors such as the curvature of the blood vessel of interest on or near the cross section of interest, or the accuracy of the examination. The user may also set the desired cross section distance.

It is desirable for this scan to be performed for at least one cardiac cycle of the patient's heart, thereby obtaining blood flow data at all phases of the heartbeat. The duration of this scan may be a fixed, pre-set period of time, or may be a period of time set for each patient or each examination.

The image forming unit 32 forms a cross-sectional image showing the shape of a first auxiliary cross section and a cross-sectional image showing the shape of a second auxiliary cross section, for example, based on data collected by auxiliary scanning of two auxiliary cross sections set near the cross section of interest. At this time, it is possible to improve image quality by using techniques such as averaging, or to select the most suitable image from two or more cross-sectional images of each auxiliary cross section.

Furthermore, the image forming unit 32 forms a group of cross-sectional images representing time-series changes in the cross-section of interest based on data collected by the main scan (repetitive scan) of the cross-section of interest. This process is realized, for example, by forming cross-sectional images from data collected for each repetition of the scan.

The processing performed by the image forming unit 32 includes, for example, noise removal (noise reduction), filtering, fast Fourier transform (FFT), and the like, similar to conventional OCT technology. Note that the processing for forming a cross-sectional image of the cross-section of interest described here is similar to the morphological image forming processing performed by the image forming unit 32.

Furthermore, the image forming unit 32 forms a phase image that represents the time series change in phase difference in the cross section of interest based on the data collected by the main scan of the cross section of interest. The data used in this process is the same as the data used to form the cross section image (group) of the cross section of interest. Therefore, there is a natural positional correspondence between the cross section image of the cross section of interest and the phase image, and registration is self-evident.

An example of a method for 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 scan points). In other words, the phase image in this example is formed for each pixel of the cross-sectional image of the cross section of interest based on the time series change in the pixel value (luminance value) of that pixel. For any pixel, the image forming unit 32 considers a graph of the time series change in the luminance value. The image forming unit 32 obtains a phase difference Δφ between two time points t1 and t2 (t2 = t1 + Δt) that are separated by a predetermined time interval Δt in this graph. Then, this phase difference Δφ is defined as the phase difference Δφ (t1) at time point t1 (more generally, any time point between two time points t1 and t2). By performing this process for each of a large number of pre-set time points, the time series change in the phase difference at the pixel is obtained.

A phase image is an image representation of the phase difference value for each pixel at each time point. This imaging process can be realized, for example, by representing the phase difference value as a display color or brightness. In this case, different colors (e.g., red) can be used to represent an increase in phase over time, and different colors (e.g., blue) can be used to represent a decrease. The magnitude of the amount of phase change can also be represented by the intensity of the display color. By adopting such a representation method, it becomes possible to represent the direction and magnitude of blood flow by color and intensity. A phase image is formed by performing the above process for each pixel.

The time series change in phase difference can be obtained by making the time interval Δt sufficiently small to ensure phase correlation. At this time, oversampling is performed in which the time interval Δt is set to a value less than the time corresponding to the resolution of the cross-sectional image when scanning with the measurement light.

The blood flow data generating unit 33 can execute, for example, a vascular region identification process, a tilt angle calculation process, and a blood flow data generation process. The blood flow data generation process includes, for example, at least a blood flow velocity calculation process, and may further include a blood vessel diameter calculation process and a blood flow amount calculation process.

In the vascular region identification process, the blood flow data generation unit 33 identifies the vascular region in each cross-sectional image that corresponds to the blood vessel of interest. Furthermore, the blood flow data generation unit 33 identifies the vascular region in the phase image that corresponds to the cross-section of interest. The vascular region is identified by analyzing the pixel values of each image (e.g., threshold processing). The vascular region in the phase image may be identified based on the vascular region in the cross-sectional image that corresponds to the cross-section of interest and the result of registration between this cross-sectional image and the phase image.

In the inclination angle calculation process, the blood flow data generation unit 33 calculates the inclination angle of the blood vessel of interest in the cross section of interest based on the image(s) formed from the data acquired by the auxiliary scan.

An example of the inclination angle calculation process will be described. See FIG. 2. Reference symbol B0 denotes a cross-sectional image (cross-sectional image of interest) in a cross-section of interest for which the vascular inclination angle is calculated. A vascular region V0 is depicted in the cross-sectional image of interest B0. Reference symbols B11 and B12 denote two cross-sectional images (auxiliary cross-sectional images) in two auxiliary cross-sections located near the cross-section of interest B0. A vascular region V11 in the auxiliary cross-section B11 of the same blood vessel (blood vessel of interest) as the vascular region V0 is depicted in the auxiliary cross-section B11. Similarly, a vascular region V12 in the auxiliary cross-section B12 of the blood vessel of interest is depicted in the auxiliary cross-section B12.

The blood flow data generating unit 33 calculates the inclination of the blood vessel of interest in the cross section of interest based on the cross section of interest B0 and the auxiliary cross section images B11 and B12. Note that the number of auxiliary cross section images referenced is not limited to two, and may be any number greater than or equal to one.

The blood flow data generating unit 33 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 cross section distance. The cross section distance may be the distance between the auxiliary cross section image B11 and the auxiliary cross section image B12. Alternatively, the cross section distance may be defined by at least one of the distance between the auxiliary cross section image B11 and the cross section image of interest B0 and the distance between the auxiliary cross section image B12 and the cross section image of interest B0. The distance between the auxiliary cross section image B11 (or B12) and the cross section image of interest B0 is defined as L.

The A-scan direction (the direction indicated by the arrow pointing downward) shown in FIG. 2 indicates, for example, the orientation of the A-scan image contained in the cross-sectional image of interest B0. This A-scan image may be, for example, the A-scan image located at the center of multiple A-scan images contained in the cross-sectional image of interest B0.

In a typical example, the blood flow data generating unit 33 can calculate the gradient 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 blood vessel regions V0, V11, and V12. More specifically, the blood flow data generating unit 33 identifies characteristic points of each of the three blood vessel regions V0, V11, and V12, and connects these characteristic points. The characteristic points referred to here include the center position (axis position), center of gravity position, and top. Methods for connecting these characteristic points include connecting them with line segments and connecting them with approximation curves (spline curves, Bezier curves, etc.).

Furthermore, the blood flow data generating unit 33 calculates the slope A based on the line connecting these feature points. When line segments are used, the blood flow data generating unit 33 can calculate the slope A based on, for example, the slope of a first line segment connecting a feature point of the vascular region V0 in the target cross-sectional image B0 and a feature point of the vascular region V11 in the auxiliary cross-sectional image B11, and the slope of a second line segment connecting the feature point of the vascular region V0 and a feature point of the vascular region V12 in the auxiliary cross-sectional image B12. As an example of this calculation process, the average value of the slopes of the two line segments can be calculated. As an example of connecting with an approximate curve, the slope of the approximate curve at the intersection position of the approximate curve and the target cross section can be calculated.

In this example, the vascular regions in three cross sections are taken into consideration, but it is also possible to determine the inclination by considering the vascular regions in two cross sections. As a specific example, the inclination A of the blood vessel of interest in the cross section of interest can be determined based on the blood vessel region V11 in the auxiliary cross section image B11 and the blood vessel region V12 in the auxiliary cross section image B12. Alternatively, the inclination A of the blood vessel of interest in the cross section of interest can be determined based on the blood vessel region V11 in the auxiliary cross section image B11 and the blood vessel region V0 in the cross section of interest B0. For example, the inclination of the first or second line segment described above can be determined and used as the inclination A of the blood vessel of interest.

In addition, in the above example, only one value of the slope A is calculated, but the slope may be calculated for two or more positions (or regions) in the vascular region V0. In this case, the two or more obtained slope values can be used separately, or a single value (e.g., the average value) obtained statistically from these slope values can be used as the slope A.

In the blood flow data generation process, the blood flow data generation unit 33 generates blood flow data for the blood vessel of interest based on the phase image formed based on the main scan (Doppler OCT) and the tilt angle determined by the blood flow data generation unit 33. As described above, in a typical example, the blood flow data generation process includes a blood flow velocity calculation process, a blood vessel diameter calculation process, and a blood flow amount calculation process.

The blood flow data generating unit 33 can calculate the blood flow velocity of blood flowing through a blood vessel of interest at a cross section of interest based on the time series change in the phase difference obtained as a phase image. The value calculated by this process may be the blood flow velocity at a certain point in time, or the time series change in blood flow velocity (blood flow velocity change data). In the former case, it is possible to selectively obtain the blood flow velocity at a specific time phase of the electrocardiogram (e.g., the R wave phase). In the latter case, the time range is the entire time during which the cross section of interest is scanned, or any part of it.

When blood flow velocity change data is obtained, the blood flow data generating unit 33 can calculate statistical values of the blood flow velocity in the time range. These statistical values include the mean, standard deviation, variance, median, maximum value, minimum value, local maximum value, and local minimum value. It is also possible to create a histogram of the blood flow velocity values.

The blood flow data generating unit 33 can calculate the blood flow velocity using the Doppler OCT technique as described above. The following relational expression, for example, is used to calculate the blood flow velocity.

Δf: Doppler shift of scattered light of measurement light n: refractive index of medium (blood) v: flow velocity of medium (blood flow velocity)
θ: Angle between the incident direction of the measurement light and the direction of the medium flow (inclination angle)
λ: central wavelength of measurement light

In a typical example, the refractive power n of the medium and the central wavelength λ of the measurement light are known, the Doppler shift Δf is obtained from the time series change in the phase difference, and the tilt angle θ is obtained from the tilt angle calculation process or the blood vessel angle distribution. The blood flow data generation unit 33 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 data generation unit 33 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 that uses a frontal image of the fundus, and a second calculation method that uses a cross-sectional image.

When the first calculation method is applied, an image of the fundus including the position of the cross section of interest is captured in advance. This fundus image is captured, for example, by the front image capture unit 60. Alternatively, a front image of the fundus previously captured and stored may be read out. A blood vessel emphasis image may also be used.

The blood flow data generating unit 33 sets the scale in the front image of the fundus based on various factors that determine the relationship between the scale on the image and the scale in real space, such as the shooting angle of view (shooting magnification), working distance, and information on the ocular optical system. This scale represents the length in real space. As a specific example, this scale corresponds to the spacing between adjacent pixels and the scale in real space (for example, pixel spacing = 10 μm). It is also possible to calculate the relationship between various values of the above factors and the scale in real space in advance, and store information that expresses this relationship in table or graph format. In this case, the scale corresponding to the above factors is selectively applied.

Based on this scale and the pixels contained in the vascular region, the blood flow data generating unit 33 calculates the diameter of the blood vessel of interest in the cross section of interest, i.e., the diameter of the vascular region. As a specific example, the blood flow data generating unit 33 can calculate the maximum or average diameter of the vascular region in various directions. Alternatively, the blood flow data generating unit 33 can approximate the contour of the vascular region to a circle or an ellipse and calculate the diameter of the circle or ellipse. Note that since the area of the vascular region can be (effectively) determined once the vascular diameter is determined, the area may be calculated instead of the vascular diameter.

The second calculation method will be described. In the second calculation method, a cross-sectional image of the fundus in the cross section of interest is used. This cross-sectional image may be a cross-sectional image based on the main scan, or may be one acquired separately. The scale in this cross-sectional 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 the working distance and information on the ocular optical system. The blood flow data generation unit 33 can, for example, determine the distance between adjacent pixels based on the length of the cross section of interest, and calculate the diameter of the blood vessel of interest in the cross section of interest in the same manner as the first calculation method.

In the blood flow calculation process, the blood flow data generation unit 33 calculates the flow rate of blood flowing through the blood vessel of interest based on the calculation results of the blood flow velocity and the blood vessel diameter. An example of this process is described below.

Let us assume that the blood flow in the blood vessel is a Hagen-Poiseuille flow. Let the diameter of the blood vessel be w, and the maximum blood flow velocity be Vm. In this case, the blood flow rate Q is expressed by the following relational equation.

The blood flow data generating unit 33 can calculate the blood flow rate Q by substituting 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 equation.

<Operation unit 50>
The operation unit 50 is used by a user to input instructions to the ophthalmic imaging apparatus 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, etc.

The operation unit 50 may include a touch panel. In this case, the display control unit 12 can display a GUI for inputting instructions and information on the touch panel.

<Front image acquisition unit 60>
The front image acquisition unit 60 acquires a front image of the fundus. Any process may be used to acquire the front image. In a 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, or the like.

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

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

<motion>
An example of the operation of the ophthalmic imaging apparatus 1 according to this embodiment will be described. An example of the operation of the ophthalmic imaging apparatus 1 is shown in Fig. 3. It is assumed that preparatory processes such as input of a patient ID, alignment of the optical system with the subject's eye, focus adjustment of the optical system, adjustment of the OCT optical path length, adjustment of the fixation position, and setting of the OCT scan range have already been performed.

(S1: Execute OCT blood flow measurement of fundus)
The ophthalmologic imaging apparatus 1 performs OCT blood flow measurement on a cross section of interest of a blood vessel of interest in the fundus of the subject's eye. The OCT blood flow measurement is performed on one or more cross sections of interest in each of the one or more blood vessels of interest. In addition, when there are multiple blood vessels passing through the cross section of interest, at least some of these blood vessels can be set as the blood vessel of interest. Conversely, the cross section of interest can also be set to cross multiple blood vessels of interest.

In OCT blood flow measurement, the scan control unit 11 controls the light source and optical scanner included in the OCT scanner 31. Under the control of the scan control unit 11, the OCT scanner 31 repeatedly scans a first cross section that intersects with the blood vessel of interest at a preset measurement position (i.e., the cross section of interest) to collect first data, and further scans one or more auxiliary cross sections that intersect with the blood vessel of interest in the vicinity of the cross section of interest to collect second data. Note that the order of collecting the first data and the second data is arbitrary.

(S2: Forming a morphological image)
The image forming unit 32 forms one or more anatomical images (B-scan images) corresponding to the cross section of interest based on the first data collected by repeatedly scanning the cross section of interest in step S1. Typically, the image forming unit 32 can form the same number of anatomical images as the number of times the scan is repeated. This allows time-series B-scan images corresponding to the cross section of interest to be obtained. Note that the image forming unit 32 may form a number of anatomical images that is less than the number of times the scan is repeated.

Furthermore, the image forming unit 32 forms a morphological image (B-scan image) corresponding to each auxiliary cross section based on the second data collected by scanning one or more auxiliary cross sections in step S2.

Each morphological image formed in step S2 is stored in the memory unit 20 as OCT data 21.

(S3: Obtain the inclination angle of the blood vessel of interest)
The blood flow data generating unit 33 obtains the inclination angle of the blood vessel of interest in the cross section of interest based on two or more anatomical images among the multiple anatomical images formed in step S2. For example, a combination of two anatomical images corresponding to two auxiliary cross sections, or a combination of a anatomical image corresponding to one auxiliary cross section and a anatomical image corresponding to the cross section of interest is used in this process.

(S4: Form a phase image)
The image forming unit 32 forms a phase image corresponding to the cross section of interest based on the first data collected by repeatedly scanning the cross section of interest in step S1.

The phase image formed in step S4 is stored in the memory unit 20 as OCT data 21.

(S5: Obtain blood flow data)
The blood flow data generating unit 33 generates blood flow data for the blood vessel of interest passing through the cross section of interest based on the inclination angle of the blood vessel of interest calculated in step S3 and the phase image formed in step S4. The blood flow data includes, for example, data representing a time series change in blood flow in the blood vessel of interest. Examples of such data include a time series change in blood flow velocity during a measurement period (typically a period of one cardiac cycle or longer) of the OCT blood flow measurement performed in step S1, and a time series change in blood flow rate per unit time during the measurement period.

The blood flow data generated in step S5 is stored in the memory unit 20 as OCT data 21. When multiple blood vessels of interest are considered, blood flow data is obtained for each of the multiple blood vessels of interest. Furthermore, for each of the multiple blood vessels of interest, its identification information (e.g., position information of the blood vessel of interest) and the corresponding blood flow data are associated with each other and stored in the memory unit 20.

(S6: Display morphological image)
The display control unit 12 causes the display device 2 to display an anatomical image of the cross section of interest. The displayed anatomical image includes, for example, a B-scan image of the cross section of interest formed in step S2. When OCT angiography is performed, the displayed anatomical image may be a vascular emphasis image. The displayed anatomical image may also be a phase image formed in step S4.

The displayed morphological image may include a blood flow state image synthesized with the vascular cross-sectional region in this B-scan image. The blood flow state image will be described later. The vascular cross-sectional region in the B-scan image is a region corresponding to the cross section of a blood vessel (vessel of interest), and is identified, for example, by analyzing at least one of the B-scan image and the phase image. Typically, the display control unit 12 and/or the data acquisition unit 30 executes the following series of processes: a process of analyzing the phase image to identify the vascular cross-sectional region; a process of identifying an image region in the B-scan image corresponding to the vascular cross-sectional region in the phase image by utilizing the trivial registration between the B-scan image and the phase image of the cross section of interest. Alternatively, the vascular cross-sectional region in the B-scan image may be identified based on the luminance distribution or pattern of the B-scan image.

An example of a morphological image displayed in step S6 is shown in FIG. 4A. Reference numeral 120 denotes an example of a morphological image displayed in step S6. The example shown in FIG. 4A represents a case in which four blood vessels are detected in the cross section of interest. The display control unit 12 displays blood flow status images 131, 132, 133, and 134 at positions in the morphological image 120 corresponding to these four blood vessels. Note that, as mentioned above, it is not essential to display the blood flow status images.

The blood flow status image 131 is, for example, an image in which the magnitude of blood flow velocity is expressed by color. The display control unit 12 determines the color (density) corresponding to the magnitude of blood flow velocity at a specified time phase by referring to a predefined lookup table (color map, density map, etc.) in which the relationship between the magnitude of blood flow velocity and color is recorded, and displays the blood flow status image 131 based on the determined color. Similar display control can also be performed for the blood flow status images 132 to 134. Also, similar display control can be performed when blood flow rate per unit time is applied.

The blood flow status image 131 may also be an image in which the direction of blood flow is represented by color. The display control unit 12 obtains a color corresponding to the direction of blood flow at a specified time phase by referring to a predefined lookup table (such as a color map) in which the relationship between the direction of blood flow and color is recorded, and displays the blood flow status image 131 based on the obtained color. Similar display control can also be performed for the blood flow status images 132 to 134. Similar display control can also be performed when the blood flow rate per unit time is applied.

In a typical example, the blood flow status image 131 may be an image in which the direction of blood flow is represented by color, and the magnitude of blood flow velocity is represented by color intensity. For example, the lookup table is set so that blood flow from the optic disc to the capillaries (i.e., blood flow in the arteries) is represented by red, and blood flow from the capillaries to the optic disc (i.e., blood flow in the veins) is represented by blue, and the color intensity increases as the blood flow velocity increases. Similar display control can be performed for the blood flow status images 132 to 134. Similar display control can also be performed when blood flow rate per unit time is applied.

(S7: Specify blood vessels)
The user designates one of the blood vessels depicted in the anatomical image displayed in step S6 using the operation unit 50. This operation is performed, for example, by clicking a desired blood vessel among those depicted in the anatomical image with a pointing device. The display control unit 12 can change the display mode of the blood vessel designated in step S7.

(S8: Display blood flow graph)
The display control unit 12 specifies the identification information (e.g., the above-mentioned position information) of the blood vessel specified in step S7, and reads out the blood flow data corresponding to the specified position information from the storage unit 20. Furthermore, the display control unit 12 (and/or the data acquisition unit 30) causes the display device 2 to display a blood flow graph based on the read out blood flow data.

An example of the information displayed in step S8 is shown in FIG. 4B. Assume that a blood vessel corresponding to the blood flow state image 132 is specified in step S7. The display control unit 12 changes the display mode of the blood flow state image 132. That is, the blood flow state image 132 is displayed in a mode different from the blood flow state images 131, 133, and 134. Furthermore, the display device 2 displays a blood flow graph 140 corresponding to the blood vessel cross-sectional area 132 together with the morphological image 120 displayed in step S6.

The blood flow graph 140 represents the time series change in blood flow in the blood vessel corresponding to the blood vessel cross-sectional area 132. In this example, the blood flow graph 140 is represented by a two-dimensional orthogonal coordinate system in which the horizontal axis (first coordinate axis) represents time t and the vertical axis (second coordinate axis) represents blood flow velocity (v).

Such a blood flow graph 140 is created based on (time series) phase images spanning the measurement period of OCT blood flow measurement. In this case, the blood flow velocity (v) on the vertical axis may be, for example, a statistical value of the values of multiple pixels included in the blood flow state image 132 at the corresponding time phase (i.e., values corresponding to the magnitude of the blood flow velocity, etc.). This statistical value may be, for example, an average value, a maximum value, a minimum value, etc. Alternatively, the blood flow velocity (v) on the vertical axis may be the value of a specified pixel (for example, a pixel located at the center, a pixel located at the center of gravity, etc.) in the blood flow state image 132.

Similarly, when blood flow rate per unit time is applied, a blood flow graph can be displayed in which the horizontal axis indicates time and the vertical axis indicates blood flow rate per unit time.

(S9: End of observation?)
The user can specify another desired blood vessel (S7). The display control unit 12 causes the display device 2 to display a blood flow graph corresponding to the newly specified blood vessel. Two or more blood vessels can be specified. In this case, two or more blood flow graphs corresponding to the two or more specified blood vessels can be displayed in parallel. Such operations and processing are repeated until observation of data and images of the subject's eye is completed (S9: No). When observation is completed (S9: Yes), the processing of this example is completed (END).

Another example of information that can be displayed in this embodiment is shown in FIG. 5. Reference numeral 100 denotes a slider for displaying and setting the time phase of blood flow. The slider 100 includes a handle 110 that can be moved along a time axis (bar) that indicates the measurement period of OCT blood flow measurement.

Reference numeral 120 denotes the anatomical image of the cross section of interest displayed in step S6. When multiple anatomical images corresponding to the cross section of interest are formed in step S2, the display control unit 12 can select and display the anatomical image corresponding to the phase currently presented by the slider 100. In other words, the position (phase) of the handle 110 of the slider 100 and the phase indicated by the anatomical image correspond to each other.

In step S4, a phase image corresponding to the morphological image 120 is formed, and in step S5, blood flow data is generated from this phase image. This blood flow data may be, for example, a time series change in blood flow velocity or a time series change in blood flow rate per unit time. In the example shown in FIG. 5, a time series change in blood flow velocity (v) is used.

The display control unit 12 displays a blood flow state image showing the state of blood flow (blood flow velocity, blood flow rate per unit time, etc.) at the time phase indicated by the slider 100 at a position in the morphological image 120 corresponding to (at least) the blood vessel of interest.

In the example shown in FIG. 5, blood flow status images 131, 132, 133, and 134 are displayed at positions in the morphological image 120 corresponding to the four blood vessels. The display control unit 12 determines the color (density) corresponding to the magnitude of the blood flow velocity in the time phase indicated by the slider 100 by referring to a predefined lookup table (color map, density map, etc.) in which the relationship between the magnitude of the blood flow velocity and color is recorded, and displays the blood flow status image 131 based on the determined color. Similar display control can also be performed for the blood flow status images 132 to 134. Similar display control can also be performed when the blood flow rate per unit time is applied.

The display control unit 12 also refers to a predefined lookup table (such as a color map) in which the relationship between the direction of blood flow and color is recorded, to determine the color corresponding to the direction of blood flow in the time phase indicated by the slider 100, and displays the blood flow status image 131 based on the determined color. Similar display control can also be performed for the blood flow status images 132 to 134. Similar display control can also be performed when the blood flow rate per unit time is applied.

In this way, the position (phase) of the handle 110 of the slider 100 and the phases indicated by the blood flow status images 131 to 134 correspond to each other.

The display control unit 12 displays a widget 150 that can be moved along the time axis (horizontal axis) of the blood flow graph 140 corresponding to the blood flow state image 132. In this example, the widget 150 is displayed on the blood flow graph 140, but the display mode of the widget 150 is not limited to this and may be any display mode that clearly indicates the position on the time axis indicated by the widget 150.

When the handle 110 of the slider 100 is moved, the display control unit 12 changes the position of the widget 150 with respect to the time axis in response to the movement of the handle 110. Conversely, when the position of the widget 150 with respect to the time axis is moved, the display control unit 12 changes the handle 110 of the slider 100 in response to the movement of the widget 150. In this way, the position (time phase) of the handle 110 of the slider 100 and the position of the widget 150 (i.e., the time phase on the time axis indicated by the widget 150) correspond to each other.

As described above, the time phase indicated by the handle 110 of the slider 100, the time phase indicated by the blood flow state images 131 to 134, and the time phase indicated by the widget 150 correspond to one another. Furthermore, when multiple morphological images with different time phases are selectively displayed, the time phase indicated by the handle 110 of the slider 100, the time phase indicated by the morphological images, the time phase indicated by the blood flow state images 131 to 134, and the time phase indicated by the widget 150 correspond to one another.

In addition, in this example, the display control unit 12 displays two widgets (slider 100 and widget 150), and executes display control of these two widgets synchronously according to the blood flow phase. However, only one widget may be displayed. Alternatively, it is also possible to display three or more widgets. In this case, display control of at least two of the three or more widgets can be executed synchronously according to the blood flow phase.

The slider 100 is operated, for example, by dragging the handle 110 using a pointing device (such as a mouse) included in the operation unit 50. The widget 150 may be operated in a similar manner.

The display control unit 12 can display the blood flow state images 131 to 134 as a moving image. In this case, the display control unit 12 can sequentially update the morphological image 120 in accordance with the time phases of the blood flow state images 131 to 134. In other words, the display control unit 12 can display the entire blood flow state images 131 to 134 and the morphological image 120 as a moving image.

Furthermore, the display control unit 12 can change the time phase indicated by the slider 100 (i.e., the position of the handle 110) and the time phase indicated by the widget 150 (i.e., the position of the widget on the time axis) in synchronization with the blood flow status images 131 to 134 (and the morphological image 120) as videos.

When OCT angiography is performed in addition to OCT blood flow measurement, the display control unit 12 can display a vascular enhancement image acquired by OCT angiography on the display device 2. The vascular enhancement image is displayed together with the morphological image, for example, in step S6 of FIG. 3. Alternatively, the vascular enhancement image is displayed as the morphological image in step S6 of FIG. 3.

When a vascular enhancement image is displayed as the morphological image in step S6 in FIG. 3, for example, the image forming unit 32 forms a B-scan image (B-scan vascular enhancement image) of the cross section of interest based on data acquired by OCT angiography. Furthermore, the display processing unit 12 causes the display device 2 to display this B-scan vascular enhancement image as a morphological image (for example, morphological image 120 in FIG. 5).

When a vascular enhancement image is displayed together with the morphological image in step S6 of FIG. 3, for example, the image forming unit 32 forms a vascular enhancement image in a predetermined cross section or a vascular enhancement image as a front image (front vascular enhancement image) based on data acquired by OCT angiography. An example of a vascular enhancement image in a predetermined cross section is a B-scan vascular enhancement image in the same cross section as the morphological image (i.e., the cross section of interest). An example of a front vascular enhancement image is a front image corresponding to any depth region of the fundus (e.g., the shallow retina, the deep retina, the choriocapillaris, the sclera, etc.) or a front image corresponding to a specific tissue of the fundus (e.g., the internal limiting membrane, the nerve fiber layer, the ganglion cell layer, the inner plexiform layer, the inner nuclear layer, the outer plexiform layer, the outer nuclear layer, the external limiting membrane, the retinal pigment epithelium, the Bruch's membrane, the choroid, the choroid-scleral boundary, the sclera, a part of any of these, a combination of at least two or more of these, etc.). Furthermore, the display processing unit 12 displays the formed vascular enhancement image on the display device 2 in parallel with a morphological image (e.g., morphological image 120 in FIG. 5).

<Ophthalmology information processing device>
An ophthalmological information processing device according to an exemplary embodiment will be described. An example of the configuration of the ophthalmological information processing device of this embodiment is shown in FIG. 6. The ophthalmological information processing device 200 stores fundus data acquired using OCT blood flow measurement, generates fundus morphological images and fundus blood flow data based on the stored data, and displays various information based on these. Furthermore, the ophthalmological information processing device 200 may be configured to store data acquired using OCT angiography and display information based on this data.

The ophthalmological information processing device 200 can display various information such as fundus morphological images, blood flow information, and vascular enhancement images on the display device 2. The display device 2 may be a part of the ophthalmological information processing device 200, or may be an external device connected to the ophthalmological information processing device 200. In addition, the ophthalmological information processing device 200 can send various information to a computer, a storage device, an ophthalmological device, etc.

The ophthalmologic information processing device 200 includes a control unit 210, a storage unit 220, a data processing unit 230, a data input unit 240, and an operation unit 250. The control unit 210 includes a display control unit 212. The storage unit 220 stores OCT data 221.

Each element of the ophthalmic information processing device 200 has, for example, the same configuration and function as the corresponding element included in the ophthalmic imaging device 1 described above. That is, the control unit 210 has the same configuration and function as the control unit 10, the display control unit 212 has the same configuration and function as the display control unit 12, the memory unit 220 has the same configuration and function as the memory unit 20, and the operation unit 250 has the same configuration and function as the operation unit 50.

The OCT data 221 may be data in the same form as the OCT data 21. For example, the OCT data 221 may include any one or more of the following (1) to (5).
(1) Data collected by OCT scan of the fundus (raw data)
(2) Image data obtained by processing raw data. (3) Intermediate data obtained during a series of processes for generating image data from raw data. (4) Blood flow data obtained by processing raw data. (5) Intermediate data obtained during a series of processes for generating blood flow data from raw data.

The data processing unit 230 performs various data processing. The data processing unit 230 may have the same configuration and functions as the image forming unit 32. For example, when the OCT data 221 includes at least one of the above OCT data (1) and (3), the data processing unit 230 can form an OCT image (morphological image, phase image, etc.) by performing processing similar to that of the image forming unit 32.

The data processing unit 230 may have the same configuration and functions as the blood flow data generating unit 33. For example, when the OCT data 221 includes at least one of the above OCT data (1), (4), and (5), the data processing unit 230 can generate blood flow data (blood flow velocity, blood flow amount, etc.) by performing processing similar to that of the blood flow data generating unit 33.

The data input unit 240 inputs the OCT data 221 and/or the data on which it is based from the outside into the ophthalmologic information processing device 200. The data input unit 240 may include, for example, a communication interface for data communication with an external device, a device for reading data from a recording medium, etc.

The display control unit 212 can execute control to display information similar to at least one of FIG. 4A, FIG. 4B, and FIG. 5 on the display device 2.

<Action and Effects>
The operation and effects of the ophthalmologic imaging apparatus and the ophthalmologic information processing apparatus according to the exemplary embodiment described above will be described.

The ophthalmic imaging device (1) according to the embodiment includes a data acquisition unit (30), a display processing unit (such as the display control unit 12), and an operation unit (50). The data acquisition unit acquires data by applying at least OCT blood flow measurement to the fundus of the subject's eye. The display processing unit displays information on a display means (display device 2).

Specifically, the display processing unit displays a morphological image (120) of the fundus based on the data (OCT data 21) acquired by the data acquisition unit. Furthermore, when any blood vessel depicted in the displayed morphological image is specified using the operation unit, the display processing unit displays a blood flow graph showing the time series change in blood flow in the specified blood vessel based on the data (OCT data 21) acquired by the data acquisition unit.

The ophthalmologic information processing device (200) according to the embodiment includes a memory unit (220), a display processing unit (such as the display control unit 212), and an operation unit (250). The memory unit stores data (OCT data 221) acquired by applying OCT blood flow measurement to the fundus of the subject eye. The display processing unit displays information on a display means (display device 2).

Specifically, the display processing unit displays a morphological image (120) of the fundus based on the data (OCT data 221) stored in the memory unit. Furthermore, when any blood vessel depicted in the displayed morphological image is specified using the operation unit, the display processing unit displays a blood flow graph showing the time series change in blood flow in the specified blood vessel based on the data (OCT data 221) acquired by the data acquisition unit.

According to this embodiment, the user can specify a desired blood vessel depicted in the morphological image while observing the morphology of the fundus through the morphological image. Furthermore, the ophthalmologic imaging device (1) or the ophthalmologic information processing device (200) can display a blood flow graph corresponding to the blood vessel specified by the user. This novel information display mode allows the user to easily observe the blood flow graph corresponding to the desired blood vessel.

In an embodiment, the blood flow graph may be configured to be represented by a two-dimensional Cartesian coordinate system in which the first coordinate axis indicates time and the second coordinate axis indicates blood flow velocity or blood flow rate per unit time.

With this configuration, the time series changes in blood flow velocity and blood flow volume per unit time can be presented as graphs. This allows the user to easily understand the time series changes in blood flow velocity and blood flow volume per unit time.

In an embodiment, the display processing unit may be configured to display at least one of the B-scan image and the phase image as a morphological image.

With this configuration, the user can easily grasp the blood flow state at cross section B while observing the morphology and/or phase state of cross section B of the fundus.

In an embodiment, the display processing unit may be configured to display a B-scan image and a blood flow state image synthesized with a vascular cross-sectional area in the B-scan image as a morphological image.

This configuration allows the user to easily understand blood flow dynamics from morphological images.

The blood flow status image may include an image in which the magnitude of the blood flow velocity or the magnitude of the blood flow volume per unit time is expressed by color. With this configuration, the magnitude of the blood flow velocity or the magnitude of the blood flow volume per unit time can be presented using color, so that the user can easily grasp the magnitude of the blood flow velocity or the magnitude of the blood flow volume per unit time.

The blood flow status image may also include an image that expresses the direction of blood flow with color. With this configuration, the direction of blood flow can be presented using color, allowing the user to easily understand the direction of blood flow.

At least one of the ophthalmic imaging device and the ophthalmic information processing device according to the embodiment can handle data acquired by applying OCT angiography to the fundus. That is, the data acquisition unit of the ophthalmic imaging device according to the embodiment may be configured to acquire data by applying OCT angiography to the fundus. Meanwhile, the storage unit of the ophthalmic information processing device according to the embodiment may be configured to store data acquired by applying OCT angiography to the fundus. Furthermore, the display processing unit of the ophthalmic imaging device and/or the ophthalmic information processing device may be configured to display a vascular enhancement image based on the data acquired by OCT angiography.

This configuration allows the user to understand the fundus morphology and blood flow dynamics as well as the distribution of fundus blood vessels.

The display processing unit can, for example, display a vascular enhancement image formed as a B-scan image as a morphological image, can display a vascular enhancement image formed as a B-scan image and a morphological image based on OCT blood flow measurement in parallel, or can display a vascular enhancement image formed as a frontal image and a morphological image in parallel.

In the ophthalmic imaging device according to the embodiment, the data acquisition unit (30) may be configured to execute the following series of processes in OCT blood flow measurement: repeatedly scanning a first cross section that intersects the blood vessel at a preset measurement position to collect first data; scanning one or more second cross sections that intersect the blood vessel near the measurement position to collect second data; calculating the inclination angle of the blood vessel at the measurement position based on the second data; and acquiring blood flow data representing the time series change of blood flow in the blood vessel passing through the first cross section based on the calculated inclination angle and the first data.

With this configuration, OCT blood flow measurements can be performed effectively to generate blood flow data, and blood flow graphs and blood flow status images can be displayed based on this blood flow data.

In the ophthalmic imaging device according to the embodiment, the data acquisition unit (30) can acquire one or more B-scan images corresponding to the first cross section based on the first data collected by repeatedly scanning the first cross section.

With this configuration, not only blood flow data but also B-scan images can be obtained from the data obtained by OCT blood flow measurement. Therefore, there is no need to perform an OCT scan to form a B-scan image separately from the OCT blood flow measurement. In addition, it is possible to obtain multiple B-scan images (time-series B-scan images) that correspond to the time-series changes in blood flow conditions.

The actions and effects of the embodiments are not limited to these, and the actions and effects provided by each item described as an embodiment, as well as the actions and effects provided by a combination of multiple items, should also be taken into consideration. In addition, any of the above-mentioned embodiments, other embodiments, publicly known technologies, etc. can be arbitrarily combined to obtain desired actions and/or effects, or for other purposes.

The configuration described above is merely one example for implementing this invention. Therefore, any modifications (omissions, substitutions, additions, etc.) may be made as appropriate within the scope of the gist of this invention.

1 Ophthalmic imaging device 2 Display device 10 Control unit 11 Scan control unit 12 Display control unit 20 Memory unit 21 OCT data 30 Data acquisition unit 31 OCT scanner 32 Image forming unit 33 Blood flow data generation unit 50 Operation unit 120 Morphological images 131, 132, 133, 134 Blood flow status image 140 Blood flow graph 200 Ophthalmic information processing device 210 Control unit 212 Display control unit 220 Memory unit 221 OCT data 230 Data processing unit 240 Data input unit 250 Operation unit

Claims (3)

a data input unit for inputting first image data of the subject's eye constructed by a first ophthalmic photographing apparatus and second image data of the subject's eye constructed by a second ophthalmic photographing apparatus different from the first ophthalmic photographing apparatus;
a display processing unit that displays on a display unit composite information of a first image based on the first image data and a second image based on the second image data,
the data input unit inputs, as the first image data, first OCT data constructed by the first ophthalmic imaging device applying an optical coherence tomography (OCT) scan to a predetermined cross section of the fundus of the subject's eye, and inputs, as the second image data, second OCT data constructed by the second ophthalmic imaging device applying an OCT blood flow measurement to a blood vessel passing through the predetermined cross section;
the display processing unit synthesizes a blood flow status image, in which the magnitude of the blood flow velocity of the blood vessel is expressed by color based on the second OCT data, onto a cross-sectional area of the blood vessel in the B-scan image of the predetermined cross section based on the first OCT data, thereby causing the display unit to display a synthesized image of the B-scan image and the blood flow status image as the synthesized information.
Ophthalmology information processing device. The display processing unit forms a phase image based on the second OCT data, and analyzes at least one of the B-scan image and the phase image to identify a position of the cross-sectional region of the blood vessel in the B-scan image.
The ophthalmologic information processing apparatus according to claim 1 . the display processing unit obtains a color corresponding to the magnitude of the blood flow velocity in a predetermined time phase by referring to a predefined lookup table in which a relationship between the magnitude of the blood flow velocity and a color is recorded, and displays the composite image by synthesizing the blood flow state image expressed in the obtained color with the cross-sectional area of the blood vessel.
The ophthalmologic information processing device according to claim 1 or 2.

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