JP2018143435A - Ocular fundus information display apparatus, ocular fundus information display method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ocular fundus information display apparatus, an ocular fundus information display method, and a program that allow a temporal change in layer thickness of the ocular fundus to be visually grasped easily.SOLUTION: An ocular fundus information display apparatus 10 includes: a thickness data acquisition part 18 for acquiring first thickness data and second thickness data on the same eye to be examined measured at different measurement time points, which are thickness data indicating a two-dimensional distribution of the layer thickness of the ocular fundus; a change data calculation part 22 for calculating change data indicating a change over time in the two-dimensional distribution of the layer thickness of the ocular fundus from a difference between the first thickness data and the second thickness data; a change map creation part 24 for creating a thickness change map indicating the change data visually; and a display part 28 for displaying the created thickness change map.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fundus information display device, a fundus information display method, and a program used for diagnosing the fundus of a subject's eye.

  In the field of ophthalmology, various images are acquired to observe the state of the eye to be examined. An image acquired in the ophthalmic field in this way is called an ophthalmic image.

  The ophthalmologic image is acquired by various ophthalmologic photographing apparatuses. As an example of an ophthalmologic photographing apparatus, an optical coherence tomography (Optical Coherence Tomography, OCT) is used to obtain a tomographic image, a fundus camera for photographing a fundus, a fundus image by laser scanning using a confocal optical system. There are scanning laser ophthalmoscope (Scanning Laser Ophthalmoscope, SLO) which obtains an image, a slit lamp which obtains an image by cutting out a light section of the cornea using slit light, and the like.

  Further, based on the fundus layer thickness information obtained from the OCT signal, a thickness map representing a two-dimensional distribution of the layer thickness is generated. By displaying the generated thickness map on the display means, the state of the layer thickness of the fundus can be observed. Further, by comparing this thickness map with the layer thickness information in the statistical database of normal eyes, the presence or absence of a disease in the eye to be examined can be examined.

  Patent Document 1 describes an apparatus that displays both the analysis result of the shape of the retinal layer and a statistical database held in a database so that they can be compared.

JP2013-153484A

  However, in comparison with the information in the statistical database, there is a drawback that the temporal change in the layer thickness cannot be recognized.

  The present invention has been made in view of such circumstances, and provides a fundus information display device, a fundus information display method, and a program that make it possible to easily visually grasp temporal changes in the layer thickness of the fundus. For the purpose.

  In order to achieve the above object, one aspect of the fundus information display device is thickness data indicating a two-dimensional distribution of the fundus layer thickness, wherein the first eye is the same and the measurement time is different. Thickness data acquisition unit for acquiring thickness data and second thickness data, and change data indicating temporal changes in the two-dimensional distribution of the fundus layer thickness from the difference between the first thickness data and the second thickness data A change data calculation unit that creates a thickness change map that visually represents the change data, and a display unit that displays the created thickness change map.

  According to this aspect, the first thickness data and the second thickness data that are the same for the eye to be examined and that have different measurement timings are acquired, and the fundus oculi layer is determined from the difference between the first thickness data and the second thickness data. Change data indicating the change over time of the two-dimensional thickness distribution is calculated and a thickness change map that visually represents the change data is created and displayed, so the temporal change in the thickness of the fundus can be visualized. Can be grasped easily.

  It is preferable to provide an alignment unit that aligns the first thickness data and the second thickness data. Thereby, a difference can be appropriately calculated from the first thickness data and the second thickness data.

  A fundus image acquisition unit that acquires a first fundus image corresponding to the first thickness data and a second fundus image corresponding to the second thickness data, and a rotational movement amount between the first fundus image and the second fundus image A rotational movement amount calculation unit that calculates the rotation amount, an image rotation unit that performs alignment in the rotational direction between the first fundus image and the second fundus image based on the rotational movement amount calculated by the rotational movement amount calculation unit, A phase-only correlation process is performed on the first fundus image and the second fundus image that have been aligned by the image rotation unit, thereby calculating a parallel movement amount between the first fundus image and the second fundus image. A movement amount calculation unit, and the alignment unit includes the first thickness data and the second thickness based on the rotational movement amount calculated by the rotational movement amount calculation unit and the parallel movement amount calculated by the parallel movement amount calculation unit. Align thickness data of Preferred. Thereby, position alignment of 1st thickness data and 2nd thickness data can be performed appropriately.

  Preferably, the rotational movement amount calculation unit calculates the rotational movement amount between the first fundus image and the second fundus image by performing phase-only correlation processing on the first fundus image and the second fundus image. . Thereby, the rotational movement amount between the first fundus image and the second fundus image, that is, the rotational movement amounts of the first thickness data and the second thickness data can be appropriately calculated.

  The rotational movement amount calculation unit includes a first conversion processing unit that performs a discrete Fourier transform on the second fundus image, a polar coordinate conversion unit that performs a polar coordinate conversion on a calculation result of the first conversion processing unit for the second fundus image, A second transformation processing unit that performs a discrete Fourier transform on a calculation result of the polar coordinate transformation unit for the second fundus image, a first data obtained in advance for the first fundus image, and a second transformation process for the second fundus image A first phase-only combining unit that performs phase-only combining processing to combine the second data obtained based on the calculation result by the unit, and a first inverse that performs inverse discrete Fourier transform on the calculation result by the first phase-only combining unit And a conversion processing unit, and the rotational movement amount is preferably calculated based on a calculation result by the first inverse conversion processing unit. Thereby, the rotational movement amount between the first fundus image and the second fundus image, that is, the rotational movement amounts of the first thickness data and the second thickness data can be appropriately calculated.

  The thickness data is preferably data generated from a signal acquired by optical coherence tomography. Thereby, an appropriate thickness change map can be created.

  Preferably, the change map creation unit creates a thickness change map to which a color corresponding to the value of the change data is added. Thereby, the thickness change map can be easily grasped visually.

  It is preferable that a front image acquisition unit that acquires a front image of the same eye to be examined is provided, and the display unit displays the front image and the thickness change map in a superimposed manner. Thereby, the position where the layer thickness has changed can be easily grasped.

  It is preferable that the change data calculation unit calculates a difference between the first thickness data and the second thickness data as change data. Thereby, the difference of the fundus layer thickness can be easily grasped visually.

  Further, the change data calculation unit is a unit time obtained by dividing a difference between the first thickness data and the second thickness data by an elapsed time which is a difference between the measurement time of the first thickness data and the measurement time of the second thickness data. The winning change rate may be calculated as change data. Thereby, the rate of change per unit time of the layer thickness of the fundus can be easily grasped visually.

  Further, the change data calculation unit may calculate, as the change data, a change rate per unit layer thickness obtained by dividing a difference between the first thickness data and the second thickness data by the first thickness data. Thereby, the rate of change per unit layer thickness of the fundus layer thickness can be easily grasped visually.

  In order to achieve the above object, one aspect of the fundus information display method is thickness data indicating a two-dimensional distribution of the fundus layer thickness, wherein the first eye is the same and the measurement time is different from each other. A thickness data acquisition step for acquiring the thickness data and the second thickness data, and change data indicating a temporal change in the two-dimensional distribution of the fundus layer thickness from the difference between the first thickness data and the second thickness data are calculated. A change data calculating step, a change map creating step for creating a thickness change map that visually represents the change data, and a display step for displaying the created thickness change map on a display unit.

  According to this aspect, the first thickness data and the second thickness data that are the same for the eye to be examined and that have different measurement timings are acquired, and the fundus oculi layer is determined from the difference between the first thickness data and the second thickness data. Change data indicating the change over time of the two-dimensional thickness distribution is calculated and a thickness change map that visually represents the change data is created and displayed, so the temporal change in the thickness of the fundus can be visualized. Can be grasped easily.

  In order to achieve the above object, one aspect of the program is the first aspect in which the computer stores thickness data indicating a two-dimensional distribution of the layer thickness of the fundus oculi and the eye to be examined is the same and the measurement time is different from each other. A thickness data acquisition step for acquiring the thickness data and the second thickness data, and change data indicating a temporal change in the two-dimensional distribution of the fundus layer thickness from the difference between the first thickness data and the second thickness data are calculated. A change data calculating step, a change map creating step for creating a thickness change map visually representing the change data, and a display step for displaying the created thickness change map on the display unit.

  According to this aspect, the first thickness data and the second thickness data that are the same for the eye to be examined and that have different measurement timings are acquired, and the fundus oculi layer is determined from the difference between the first thickness data and the second thickness data. Change data indicating the change over time of the two-dimensional thickness distribution is calculated and a thickness change map that visually represents the change data is created and displayed, so the temporal change in the thickness of the fundus can be visualized. Can be grasped easily.

  A computer-readable non-transitory recording medium recording the program is also included in this aspect.

  According to the present invention, a temporal change in the thickness of the fundus can be easily grasped visually.

Block diagram showing the configuration of the fundus information display device The figure which shows an example of the display part by which the several thickness map was displayed The flowchart which shows the display process of the thickness change map which a fundus information display apparatus performs The figure which shows an example of the display part by which the several thickness change map was displayed Block diagram showing the configuration of the fundus information display device The flowchart which shows the display process of the thickness change map which a fundus information display apparatus performs The figure which shows an example of a front image The figure which shows an example of the display part by which the several thickness change map was superimposed and displayed on the front image Block diagram showing the configuration of the fundus information display device Block diagram showing an example of the alignment unit The flowchart which shows the display process of the thickness change map which a fundus information display apparatus performs

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

<First Embodiment>
[Configuration of fundus information display device]
FIG. 1 is a block diagram illustrating a configuration of a fundus information display apparatus 10 according to the first embodiment. As shown in FIG. 1, the fundus information display device 10 includes a control unit 12, a communication unit 14, an image memory 16, a thickness data acquisition unit 18, an alignment unit 20, a change data calculation unit 22, a thickness change map creation unit 24, It comprises an operation unit 26, a display unit 28, and the like.

  The control unit 12 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory) (not shown). Various programs and control data are stored in the ROM. The RAM temporarily stores programs and data executed by the CPU.

  The control unit 12 executes a program read from the ROM in the CPU, thereby functioning as a control unit that performs overall control of each unit of the fundus information display device 10 and also functions as a calculation unit that performs various calculation processes.

  The communication unit 14 includes a communication interface (not shown), and transmits / receives data to / from an external server 100 connected to the communication interface. The server 100 constitutes a database for various ophthalmic images and diagnostic data.

  The image memory 16 is a temporary storage unit for various data including image data, and data is read and written through the control unit 12. Various data fetched from the server 100 via the communication unit 14 is stored in the image memory 16.

  The thickness data acquisition unit 18 transmits a thickness map, which is an example of thickness data indicating a two-dimensional distribution of the layer thickness of the fundus of the specified eye to be examined, via the communication unit 14 in accordance with the command from the control unit 12. Get from.

  The alignment unit 20 aligns the plurality of thickness maps acquired by the thickness data acquisition unit 18.

  The change data calculation unit 22 calculates change data indicating a change in the two-dimensional distribution of the layer thickness of the fundus of the eye to be examined from the difference between the two thickness maps aligned by the alignment unit 20.

  The thickness change map creation unit 24 creates a thickness change map that visually represents the change data by adding a color or pattern according to the value of the change data from the change data calculated by the change data calculation unit 22.

  The operation unit 26 includes operation members such as operation buttons and a keyboard, and outputs operation information input from the operation members to the control unit 12. The control unit 12 executes various processes according to the operation information input from the operation unit 26.

  The display unit 28 displays various ophthalmic images, the thickness map acquired by the thickness data acquisition unit 18, the thickness change map generated by the thickness change map generation unit 24, diagnostic information about the patient, and the like. As the display unit 28, for example, a liquid crystal display, an organic EL display, or the like can be applied. A touch panel in which the operation unit 26 and the display unit 28 are integrated may be used.

[Display method of thickness change map]
FIG. 2 is a diagram illustrating an example of the display unit 28 on which a plurality of thickness maps are displayed. In FIG. 2, four thickness maps MT ₁ , MT ₂ , MT ₃ , and MT ₄ are displayed. In addition to the thickness map, a thickness change map display icon _ID is displayed to be selectable.

  The thickness map is a visual representation of data (thickness data) indicating a two-dimensional distribution of the fundus layer thickness generated from a signal measured by optical coherence tomography.

The thickness maps MT ₁ , MT ₂ , MT ₃ , and MT ₄ are generated from retinal thickness data relating to the same eye of the same patient. Thickness maps MT ₁ , MT ₂ , MT ₃ , and MT ₄ have different measurement timings for thickness data, and here, thickness data is measured in the order of thickness maps MT ₁ , MT ₂ , MT ₃ , and MT _4. To do. The thickness maps MT ₁ , MT ₂ , MT ₃ , and MT ₄ are recorded in the server 100, acquired from the server 100 by the thickness data acquisition unit 18, and displayed on the display unit 28.

In the state in which the thickness map is displayed on the display unit 28 in this manner, the fundus information display device 10 displays the display unit 28 when the observer changes the thickness change map display icon _ID by operating the operation unit 26. A thickness change map is displayed. The thickness change map is a visual representation of change data indicating changes with time of two thickness data.

  FIG. 3 is a flowchart illustrating a thickness change map display process (an example of a fundus information display method) executed by the fundus information display apparatus 10.

When the thickness change map display icon _ID is selected by the operation unit 26, the control unit 12 initializes the variable n to 0 (step S1).

  Next, the control unit 12 increments the variable n (step S2).

Subsequently, the thickness data acquisition unit 18 receives thickness data DT _n (an example of first thickness data) and thickness map MT _{n + 1} that are thickness data for each pixel of the thickness map MT _n from the server 100 via the communication unit 14. Thickness data DT _{n + 1} (an example of second thickness data) that is thickness data for each pixel is acquired (step S3, an example of a thickness data acquisition step).

In the case n = 1, the acquiring the thickness data DT ₁ and thickness data DT ₂ in the thickness map MT ₂ of the thickness map MT _1.

Next, the alignment unit 20 performs alignment of the thickness data DT _n and the thickness data DT _{n + 1} . Further, the change data calculation unit 22 calculates the difference between the layer thickness values at the positions corresponding to the thickness data DT _n and the thickness data DT _{n + 1} after alignment, and the layer thickness difference data DD _n is changed over time. (Step S4, an example of a change data calculation step).

Then, the thickness change map creation unit 24 creates a thickness change map MD _n based on the change data (step S5, an example of a change map generation step). Here, it is assumed that the thickness change map MD _n visually represents a change in the two-dimensional distribution of the layer thickness of the fundus of the eye to be examined by adding a color corresponding to the value of the difference data DD _n .

Next, the control part 12 determines whether all the thickness change maps were created (step S6). If all thickness change maps have not been created, the process returns to step S2 and the same processing is repeated. That is, until the creation of all the thickness change map completed, increments n (step S2), the acquired thickness data DT _n and thickness data _{DT n + 1} (step S3), and calculates the difference data DD _n (step S4 ), to create a thickness change map MD _n (step S5).

Here, from the _four thickness maps MT _{1 to} MT 4 displayed on the display unit 28, the thickness change map MD ₁ between the thickness map MT ₁ and the thickness map MT ₂ and the thickness between the thickness map MT ₂ and the thickness map MT ₃ are displayed. The same processing is repeated until three thickness change maps of the change map MD ₂ and the thickness change map MD ₃ of the thickness map MT ₃ and the thickness map MT ₄ are created.

When the creation of all the thickness change maps is completed, the display unit 28 displays the created thickness change maps MD _{1 to} MD _n (step S7, an example of a display process), and the process of this flowchart is finished.

FIG. 4 is a diagram illustrating an example of the display unit 28 on which a plurality of thickness change maps are displayed. In FIG. 4, three thickness change maps MD ₁ , MD ₂ , and MD ₃ are displayed. These thickness change maps may be recorded in the server 100.

As shown in FIG. 4, when a thickness change map is displayed on the display unit 28, a thickness map display icon _IT is displayed so as to be selectable. In this state, the fundus information display device 10, when the thickness map display icon I _T is selected by the viewer operating the operation unit 26 to display the thickness map on the display unit 28.

  As described above, according to the present embodiment, the thickness data indicates a two-dimensional distribution of the fundus layer thickness, and the difference represents a difference between a plurality of thickness data with the same eye to be examined and different measurement timings. By calculating the data and displaying a thickness change map that visually represents the difference data, the observer can easily visually grasp the temporal change in the two-dimensional distribution of the fundus layer thickness. .

In the present embodiment, the change data calculation unit 22 calculates the difference between the layer thickness values at the corresponding positions of the thickness data DT _n and the thickness data DT _{n + 1} after alignment, and the difference data DD _n of the layer thickness is calculated. However, the change rate per unit layer thickness obtained by dividing the difference data DD _n for each pixel by the thickness data DT _n for each pixel may be calculated as the change data.

It is also possible to calculate the rate of change per unit obtained by dividing the time by the elapsed time is a difference between the measurement time of the measurement time and thickness data DT n _{+ 1} of the differential data DD _n of thickness data DT _n for each pixel as the change data.

  Here, the thickness map and thickness change map of the retina have been described, but the present invention can also be applied to the thickness map and thickness change map of a desired layer such as a nerve fiber layer or a ganglion cell layer.

<Second Embodiment>
[Configuration of fundus information display device]
FIG. 5 is a block diagram illustrating a configuration of a fundus information display device 40 according to the second embodiment. In addition, the same code | symbol is attached | subjected to the part which is common in the block diagram shown in FIG. 1, and the detailed description is abbreviate | omitted.

  As shown in FIG. 5, the fundus information display device 40 includes a front image acquisition unit 30. The front image acquisition unit 30 acquires a front image of the eye to be examined for creating a thickness change map.

[Display method of thickness change map]
FIG. 6 is a flowchart showing the thickness change map display process executed by the fundus information display apparatus 40. In addition, the same code | symbol is attached | subjected to the part which is common in the flowchart shown in FIG. 3, and the detailed description is abbreviate | omitted.

  In this embodiment, when displaying the thickness map and the thickness change map, the front image is superimposed and displayed.

The processing from step S1 to step S6 is the same as that in the first embodiment. Thickness change map _MD 1 to MD ₃ created in this embodiment is assumed to be the same as the thickness change map _MD 1 to MD ₃ shown in FIG.

  If it is determined in step S6 that all thickness change maps have been created, the front image acquisition unit 30 acquires a front image P of the eye to be examined that is the same as the eye to be examined of the created thickness change map (step S6). S8).

  FIG. 7 is a diagram illustrating an example of the front image P. As illustrated in FIG. Here, the fundus image captured by the fundus camera is acquired as the front image P from the server 100 via the communication unit 14. In addition, you may acquire the front image P produced | generated from the signal measured by optical coherence tomography.

Finally, the display unit 28 displays the created thickness change maps MD _{1 to} MD _n superimposed on the front image (step S9), and ends the process of this flowchart. If necessary, the alignment unit 20 aligns the thickness change maps MD _{1 to} MD _n and the front image P in advance.

FIG. 8 is a diagram illustrating an example of the display unit 28 in which a plurality of thickness change maps are superimposed on the front image P. In FIG. 8, the transparency of the front image P is increased and superimposed on the _three thickness change maps MD ₁ , MD ₂ , and MD ₃ .

  As described above, by superimposing and displaying the front image on the created thickness change map, it is possible for the observer to easily grasp the temporal change and position of the two-dimensional distribution of the fundus layer thickness. it can.

<Third Embodiment>
[Configuration of fundus information display device]
FIG. 9 is a block diagram illustrating a configuration of a fundus information display apparatus 50 according to the third embodiment. In addition, the same code | symbol is attached | subjected to the part which is common in the block diagram shown in FIG. 5, and the detailed description is abbreviate | omitted.

  As shown in FIG. 9, the alignment unit 20 according to this embodiment includes a rotation movement amount calculation unit 52, an image rotation unit 54, and a parallel movement amount calculation unit 56.

  When aligning the plurality of thickness maps, the alignment unit 20 first aligns the fundus images, and relatively aligns the respective optical coherence tomography imaging positions with respect to the fundus image.

  The fundus images are aligned with each other between the base image and the target image acquired by the front image acquisition unit 30 (an example of the fundus image acquisition unit) when the two fundus images to be aligned are a base image and a target image. The rotational movement amount is calculated at the sub-pixel level, and based on this rotational movement amount, alignment in the rotational direction is performed between the base image and the target image. Thereafter, the alignment unit 20 calculates a parallel movement amount between the base image and the target image that have been aligned at the sub-pixel level, and parallels between the base image and the target image based on the parallel movement amount. Align the direction.

  The alignment unit 20 calculates a rotational movement amount and a parallel movement amount between the base image and the target image by performing a phase-only correlation process described later. Here, the alignment unit 20 calculates in advance POC (Phase Only Correlation) data (first data) for the base image used for the phase-only correlation process. Hereinafter, the POC data for the base image may be referred to as base POC data, and the POC data for the target image may be referred to as target POC data. When the target image POC data (second data) is calculated, the alignment unit 20 continues the phase-only correlation process using the target POC data and the base POC data obtained in advance. As a result, the processing load is reduced and the processing time is shortened, and a minute positional deviation amount is calculated.

(Phase only correlation processing)
In the phase only correlation process in the present embodiment, a known phase only correlation function is used.

First, a base image whose image size is N ₁ × N ₂ (N ₁ and N ₂ are positive integers) is f (n ₁ , n ₂ ), and a target image is g (n ₁ , n ₂ ). Here, n ₁ = −M ₁ ,..., M ₁ on the discrete space, N ₁ = 2M ₁ +1 (M ₁ is a positive integer), and f (n ₁ , n ₂ ) two-dimensional discrete Assuming that the calculation result of the Fourier transform (hereinafter referred to as DFT) is F (k ₁ , k ₂ ), F (k ₁ , k ₂ ) is expressed as equation (1).

In equation (1), AF (k ₁ , k ₂ ) is the amplitude component of f (n ₁ , n ₂ ), and e ^{jθF (k1, k2)} is the phase component of f (n ₁ , n ₂ ). .

Similarly, in a discrete space, n ₂ = −M ₂ ,..., M ₂ , N ₂ = 2M ₂ +1 (M ₂ is a positive integer), and a two-dimensional DFT of g (n ₁ , n ₂ ) If G (k ₁ , k ₂ ) is G (k ₁ , k ₂ ), then G (k ₁ , k ₂ ) is expressed as in equation (2).

In Expression (2), A _G (k ₁ , k ₂ ) is an amplitude component of g (n ₁ , n ₂ ), and e ^{jθG (k1, k2)} is a phase component of g (n ₁ , n ₂ ). is there.

  The phase only synthesis function used in the phase only synthesis process is defined as in equation (3) using equations (1) and (2).

  The phase-only correlation function in the present embodiment is obtained by applying a two-dimensional inverse discrete Fourier transformation (hereinafter referred to as IDFT) to the phase-only synthesis function of Equation (3) as shown in Equation (4). expressed.

The 2-dimensional images _s c of the continuous space is defined _(x 1, _{x 2),} by a minute amount of movement [delta] ₁ in _{x 1} direction and the image obtained by shifting the _{x 2} direction by a minute amount of movement [delta] ₂ is , S _c (x ₁ −δ ₁ , x ₂ −δ ₂ ). A two-dimensional image f (n ₁ , n ₂ ) on the discrete space sampled at the sampling interval T ₁ is defined as in Expression (5).

Similarly, a two-dimensional image g (n ₁ , n ₂ ) on the discrete space sampled at the sampling interval T ₂ is defined as in Expression (6).

In the formula (5) and _{(6), n 1 = -M} 1, ···, a _{M 1, n 2 = -M 2} , ···, a _{M 2.} Thereby, the phase-only correlation function regarding the two-dimensional images f (n ₁ , n ₂ ) and g (n ₁ , n ₂ ) on the discrete space is expressed in a general form as in Expression (7). In equation (7), α = 1.

  The alignment unit 20 that performs the phase-only correlation process will be described. FIG. 10 is a block diagram illustrating an example of the alignment unit 20.

(Rotational movement amount calculation unit)
The rotational movement amount calculation unit 52 calculates the rotational movement amount between the base image and the target image. Specifically, the rotational movement amount calculation unit 52 calculates the rotational movement amount between the base image and the target image by performing phase-only correlation processing on the base image and the target image. As shown in FIG. 10, such a rotational movement amount calculation unit 52 includes a first conversion processing unit 60, a logarithmic conversion unit 62, a polar coordinate conversion unit 64, a second conversion processing unit 66, A first phase only synthesis unit 68 and a first inverse transform processing unit 70 are provided.

  The first conversion processing unit 60 performs a two-dimensional DFT process on the base image. The first conversion processing unit 60 performs a two-dimensional DFT process on the target image. The two-dimensional DFT process performed by the first conversion processing unit 60 includes a two-dimensional DFT and a known shift process for shifting a quadrant with respect to the calculation result of the two-dimensional DFT. Hereinafter, this shift process may be referred to as “shift”. Note that the two-dimensional DFT performed by the first transformation processing unit 60 may be a two-dimensional FFT (Fast Fourier Transformation).

  The logarithmic conversion unit 62 performs logarithmic conversion on the calculation result of the first conversion processing unit 60 for the base image. In addition, the logarithmic conversion unit 62 performs logarithmic conversion on the calculation result of the first conversion processing unit 60 for the target image. The logarithmic transformation by the logarithmic transformation unit 62 has an effect of compressing an amplitude spectrum that tends to concentrate in a low frequency region of a spatial frequency in a natural image.

The polar coordinate conversion unit 64 performs polar coordinate conversion on the calculation result of the logarithmic conversion unit 62 for the base image. Further, the polar coordinate conversion unit 64 performs polar coordinate conversion on the calculation result of the logarithmic conversion unit 62 for the target image. When logarithmic conversion by the logarithmic conversion unit 62 is not performed, the polar coordinate conversion unit 64 performs polar coordinate conversion on the calculation result by the first conversion processing unit 60 for the base image, and the first conversion processing unit 60 for the target image. Polar coordinate transformation is applied to the result of the calculation. Polar conversion by polar coordinate transformation unit 64 is a process of converting the movement amount of the rotational direction to the amount of movement of the parallel direction (n ₁ direction and n ₂ direction) in the formula (1) to (7).

  The second conversion processing unit 66 performs a two-dimensional DFT process (two-dimensional DFT + shift) on the calculation result of the polar coordinate conversion unit 64 for the base image, as shown in Expression (1). The processing result of the second conversion processing unit 66 for the base image is obtained as base POC data (first data) normalized by the amplitude component prior to the arithmetic processing by the first phase-only combining unit 68, for example, the control unit 12 Are stored in advance in a ROM (not shown). Further, as shown in Expression (2), the second conversion processing unit 66 performs two-dimensional DFT processing (two-dimensional DFT + shift) on the calculation result of the polar coordinate conversion unit 64 for the target image. Note that the two-dimensional DFT performed by the second conversion processing unit 66 may also be a two-dimensional FFT.

  As shown in Expression (3), the first phase only synthesis unit 68 is based on the base POC data (first data) obtained in advance for the base image and the calculation result by the second conversion processing unit 66 for the target image. Then, phase-only combining processing is performed for combining the target POC data (second data) normalized by the amplitude component.

  The first inverse transform processing unit 70 performs a two-dimensional IDFT process on the calculation result by the first phase only synthesis unit 68. The two-dimensional IDFT process performed by the first inverse transform processing unit 70 includes a two-dimensional IDFT and a known shift process for shifting the quadrant with respect to the calculation result of the two-dimensional IDFT. The two-dimensional IDFT may be calculated by a two-dimensional inverse fast Fourier transformation (hereinafter referred to as IFFT).

  The rotational movement amount calculation unit 52 calculates the rotational movement amount based on the calculation result by the first inverse conversion processing unit 70. Specifically, the rotational movement amount calculation unit 52 specifies the peak position based on the calculation result by the first inverse conversion processing unit 70, thereby moving the rotational direction movement amount (rotational movement amount, displacement amount) at the pixel level. ) Is calculated. Thereafter, the rotational movement amount calculation unit 52 specifies the pixel position when the correlation value of the phase-only correlation function shown in Expression (7) is maximum in the vicinity of the peak position specified at the pixel level. The amount of movement in the rotation direction (rotation movement amount, displacement amount) is calculated at the pixel level.

  The rotational movement amount calculation unit 52 has been described as calculating the movement amount of the target image in the rotation direction with reference to the base image, but is not limited thereto. The rotational movement amount calculation unit 52 may calculate the movement amount in the rotation direction of the base image based on the target image.

  Further, the rotational movement amount calculation unit 52 does not have to calculate the rotational movement amount by the phase-only correlation process. The rotational movement amount is calculated by a known method, and the calculated rotational movement amount is used as the image rotation unit 54. May be output.

(Image rotation part)
The image rotation unit 54 aligns the rotation direction between the base image and the target image based on the rotation movement amount calculated by the rotation movement amount calculation unit 52. Specifically, the image rotation unit 54 is based on the rotation movement amount calculated by the rotation movement amount calculation unit 52, with respect to the target image so that the rotation movement amount becomes zero with reference to the base image. Perform alignment.

(Translation amount calculation unit)
The parallel movement amount calculation unit 56 calculates the parallel movement amount between the base image and the target image that have been aligned by the image rotation unit 54. Specifically, the parallel movement amount calculation unit 56 performs a phase-only correlation process on the base image and the target image that have been aligned by the image rotation unit 54, so that the parallel between the base image and the target image is performed. The amount of movement is calculated. As shown in FIG. 10, the parallel movement amount calculation unit 56 includes a third conversion processing unit 72, a second phase only combining unit 74, and a second inverse conversion processing unit 76.

  The third conversion processing unit 72 performs a two-dimensional DFT process (two-dimensional DFT + shift) on the base image as shown in Expression (1). The processing result of the third conversion processing unit 72 for the base image is obtained as base POC data (third data) normalized by the amplitude component prior to the arithmetic processing by the second phase only combining unit 74, for example, the storage unit 212. Saved in advance. In addition, the third conversion processing unit 72 performs a two-dimensional DFT process (two-dimensional DFT + shift) on the target image as shown in Expression (2). Note that the two-dimensional DFT performed by the third conversion processing unit 72 may be a two-dimensional FFT.

  As shown in Expression (3), the second phase only combining unit 74 is based on the base POC data (third data) obtained in advance for the base image and the calculation result by the third conversion processing unit 72 for the target image. Then, a phase only synthesis process for synthesizing the target POC data (fourth data) normalized by the amplitude component is performed.

  The second inverse transform processing unit 76 performs a two-dimensional IDFT process (two-dimensional IDFT + shift) on the calculation result by the second phase only synthesis unit 74. Note that the two-dimensional IDFT performed by the second inverse transform processing unit 76 may be a two-dimensional IFFT.

  The parallel movement amount calculation unit 56 calculates the parallel movement amount based on the calculation result by the second inverse transformation processing unit 76. Specifically, the parallel movement amount calculation unit 56 specifies the peak position based on the calculation result by the second inverse conversion processing unit 76, thereby moving the movement amount in the parallel direction (parallel movement amount, positional deviation amount) at the pixel level. ) Is calculated. After that, the parallel movement amount calculation unit 56 specifies the pixel position when the correlation value of the phase-only correlation function shown in Expression (7) is maximum in the vicinity of the peak position specified at the pixel level. The amount of movement in the parallel direction (parallel movement amount, displacement amount) is calculated at the pixel level.

  Although the parallel movement amount calculation unit 56 has been described as calculating the movement amount of the target image in the parallel direction based on the base image, the present invention is not limited to this. The parallel movement amount calculation unit 56 may calculate the movement amount of the base image in the parallel direction based on the target image.

As described above, the alignment unit 20 can calculate the rotational movement amount and the parallel movement amount between the base image and the target image. Based on the calculated rotational movement amount and parallel movement amount, the positions of the acquired thickness data DT _n and thickness data DT _{n + 1} can be adjusted.

[Video creation method]
FIG. 11 is a flowchart showing a moving image display process executed by the fundus information display apparatus 50 according to the present embodiment. In addition, the same code | symbol is attached | subjected to the part which is common in the flowchart shown in FIG. 6, and the detailed description is abbreviate | omitted.

As before, when the thickness change map display icon _ID is selected by the operation unit 26, the control unit 12 initializes the variable n to 0 (step S1).

Next, the control unit 12 increments the variable n (step S2). Then, the front image acquisition unit 30, fundus images _{P n + 1} which corresponds via the communication unit 14 from the server 100 (an example of a first fundus image) fundus image _{P n} corresponding to a thickness map MT _n and thickness map _{MT n + 1} (Example of second fundus image) is acquired (step S10).

Here, the fundus image P _n corresponding to a thickness map MT _n, taken fundus image P _n captured during the measurement of the thickness map MT _n, that is, when obtaining the tomographic image by optical coherence tomography by the fundus camera the eye fundus _Point to image _Pn .

Next, the rotational movement amount calculation unit 52 of the alignment unit 20 calculates the rotational movement amount between the fundus image P _n and the fundus image P _{n + 1} (step S11). In addition, the image rotation unit 54 performs alignment in the rotation direction between the fundus image P _n and the fundus image P _{n + 1} based on the rotation movement amount calculated by the rotation movement amount calculation unit 52 (step S12).

Next, the parallel movement amount calculation unit 56 calculates the parallel movement amount between the fundus image P _n and the fundus image P _{n + 1} that have been aligned by the image rotation unit 54 (step S13).

Subsequently, the thickness data acquisition unit 18 acquires the thickness data DT _n and the thickness data DT _{n + 1} from the server 100 via the communication unit 14 (step S3).

The alignment unit 20 aligns the thickness data DT _n and the thickness data DT _{n + 1} based on the relative positions of the fundus image P _n and the fundus image P _{n + 1} that have been aligned in advance. Further, the change data calculation unit 22 calculates the difference between the layer thickness values at the positions corresponding to the thickness data DT _n and the thickness data DT _{n + 1} after alignment, and the layer thickness difference data DD _n is changed over time. Is calculated as change data (step S4).

  The following processing is the same as in the second embodiment.

As described above, according to the present embodiment, since the thickness data DT _n and the thickness data DT _{n + 1} can be properly aligned, the thickness change map can be appropriately created, The temporal change of the two-dimensional distribution of the layer thickness can be easily grasped visually.

<Others>
In the embodiment described so far, for example, the control unit 12, the thickness data acquisition unit 18, the alignment unit 20, the change data calculation unit 22, the thickness change map creation unit 24, the front image acquisition unit 30, and the rotational movement amount calculation unit 52. , Image rotation unit 54, parallel movement amount calculation unit 56, first conversion processing unit 60, logarithmic conversion unit 62, polar coordinate conversion unit 64, second conversion processing unit 66, first phase only synthesis unit 68, first inverse conversion process The hardware structure of the processing unit (processing unit) that executes various processes such as the unit 70, the third conversion processing unit 72, the second phase only synthesis unit 74, and the second inverse conversion processing unit 76 is as follows. There are various processors as shown. For various processors, the circuit configuration can be changed after manufacturing a CPU (Central Processing Unit), FPGA (Field Programmable Gate Array), which is a general-purpose processor that functions as various processing units by executing software (programs). Includes a dedicated electrical circuit that is a processor having a circuit configuration specifically designed to execute a specific process such as a programmable logic device (PLD) or ASIC (Application Specific Integrated Circuit) It is.

  One processing unit may be configured by one of these various processors, or may be configured by two or more processors of the same type or different types (for example, a plurality of FPGAs or a combination of CPUs and FPGAs). May be. Further, the plurality of processing units may be configured by one processor. As an example of configuring a plurality of processing units with one processor, first, as represented by a computer such as a server and a client, one processor is configured with a combination of one or more CPUs and software. There is a form in which the processor functions as a plurality of processing units. Second, as represented by a system-on-chip (SoC) or the like, there is a form of using a processor that realizes the functions of the entire system including a plurality of processing units with a single integrated circuit (IC) chip. is there. As described above, various processing units are configured using one or more various processors as a hardware structure.

  Further, the hardware structure of these various processors is more specifically an electric circuit (circuitry) in which circuit elements such as semiconductor elements are combined.

  The fundus information display method according to the present embodiment is configured as a program for causing a computer to execute each of the above steps, and is non-temporary such as a CD-ROM (Compact Disk-Read Only Memory) that stores the configured program. It is also possible to configure a recording medium.

  The technical scope of the present invention is not limited to the scope described in the above embodiment. The configurations and the like in the embodiments can be appropriately combined between the embodiments without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10 Fundus information display apparatus 12 Control part 14 Communication part 16 Image memory 18 Thickness data acquisition part 20 Positioning part 22 Change data calculation part 24 Thickness change map creation part 26 Operation part 28 Display part 30 Front image acquisition part 40 Fundus information display apparatus 50 fundus information display device 52 rotational movement amount calculation unit 54 image rotation unit 56 parallel movement amount calculation unit 60 first conversion processing unit 62 logarithmic conversion unit 64 polar coordinate conversion unit 66 second conversion processing unit 68 first phase only synthesis unit 70 first 1 Inverse transformation processing unit 72 Third transformation processing unit 74 Second phase limited synthesis unit 76 Second inverse transformation processing unit 100 Server _IT thickness map display icon MD ₁ thickness change map MD ₂ thickness change map MD ₃ thickness change map MD ₄ Thickness change map MT ₁ thickness map MT ₂ thickness map MT ₃ thickness map MT ₄ thickness map P front image S1 to S9 thickness change map Display process

Claims (13)

Thickness data acquisition unit that obtains first thickness data and second thickness data that are two-dimensional distributions of the fundus layer thickness and have the same eye and different measurement times;
A change data calculation unit that calculates change data indicating a change over time of a two-dimensional distribution of the layer thickness of the fundus oculi from the difference between the first thickness data and the second thickness data;
A change map creation unit that creates a thickness change map that visually represents the change data;
A display unit for displaying the created thickness change map;
Fundus information display device.   The fundus information display device according to claim 1, further comprising an alignment unit configured to align the first thickness data and the second thickness data. A fundus image acquisition unit that acquires a first fundus image corresponding to the first thickness data and a second fundus image corresponding to the second thickness data;
A rotational movement amount calculation unit for calculating a rotational movement amount between the first fundus image and the second fundus image;
An image rotation unit that performs alignment in the rotation direction between the first fundus image and the second fundus image based on the rotation movement amount calculated by the rotation movement amount calculation unit;
Parallel movement between the first fundus image and the second fundus image is performed by performing phase-only correlation processing on the first fundus image and the second fundus image that have been aligned by the image rotation unit. A parallel movement amount calculation unit for calculating the amount;
With
The alignment unit is configured to determine the first thickness data and the second thickness based on the rotational movement amount calculated by the rotational movement amount calculation unit and the parallel movement amount calculated by the parallel movement amount calculation unit. The fundus information display apparatus according to claim 2, wherein the data alignment is performed.   The rotational movement amount calculation unit performs a phase-only correlation process on the first fundus image and the second fundus image, thereby calculating a rotational movement amount between the first fundus image and the second fundus image. The fundus oculi information display device according to claim 3 to calculate. The rotational movement amount calculation unit
A first transformation processing unit for performing a discrete Fourier transform on the second fundus image;
A polar coordinate conversion unit that performs polar coordinate conversion on a calculation result of the first conversion processing unit for the second fundus image;
A second transformation processing unit that performs a discrete Fourier transform on a calculation result by the polar coordinate transformation unit for the second fundus image;
A phase-only combining process is performed for combining the first data obtained in advance for the first fundus image and the second data obtained based on the calculation result of the second conversion processing unit for the second fundus image. A one-phase limited synthesis unit;
A first inverse transform processing unit that performs an inverse discrete Fourier transform on the calculation result by the first phase only synthesis unit,
The fundus information display device according to claim 4, wherein the rotational movement amount is calculated based on a calculation result by the first inverse conversion processing unit.   The fundus information display device according to any one of claims 1 to 5, wherein the thickness data is data generated from a signal acquired by optical coherence tomography.   The fundus information display device according to any one of claims 1 to 6, wherein the change map creating unit creates the thickness change map to which a color corresponding to a value of the change data is added. A front image acquisition unit that acquires a front image of the same eye to be examined;
The fundus information display device according to any one of claims 1 to 7, wherein the display unit superimposes and displays the front image and the thickness change map.   The fundus information display device according to any one of claims 1 to 8, wherein the change data calculation unit calculates a difference between the first thickness data and the second thickness data as change data.   The change data calculation unit divides a difference between the first thickness data and the second thickness data by an elapsed time which is a difference between the measurement time of the first thickness data and the measurement time of the second thickness data. The fundus information display device according to any one of claims 1 to 8, wherein the change rate per unit time is calculated as change data.   The change data calculation unit calculates, as change data, a change rate per unit layer thickness obtained by dividing a difference between the first thickness data and the second thickness data by the first thickness data. The fundus information display device according to any one of the above. Thickness data acquisition process for acquiring first thickness data and second thickness data, which are two-dimensional distributions of the fundus layer thickness and have the same eye and different measurement times;
A change data calculation step of calculating change data indicating a change over time of a two-dimensional distribution of the layer thickness of the fundus oculi from the difference between the first thickness data and the second thickness data;
A change map creating step for creating a thickness change map that visually represents the change data;
A display step of displaying the created thickness change map on a display unit;
A method for displaying fundus information. On the computer,
Thickness data acquisition process for acquiring first thickness data and second thickness data, which are two-dimensional distributions of the fundus layer thickness and have the same eye and different measurement times;
A change data calculation step of calculating change data indicating a change over time of a two-dimensional distribution of the layer thickness of the fundus oculi from the difference between the first thickness data and the second thickness data;
A change map creating step for creating a thickness change map that visually represents the change data;
A display step of displaying the created thickness change map on a display unit;
A program for running

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