JP2019037541A - Medical image processing apparatus, control method for medical image processing apparatus, and program - Google Patents

Abstract

To provide a mechanism capable of easily setting a display method for a plurality of medical images photographed at different photographing points of time, in a medical image processing apparatus.SOLUTION: A medical image processing apparatus comprises: storage means for storing a plurality of medical images obtained by photographing the same part at different dates; acquisition means for acquiring a feature amount of a lesion identified from each of the plurality of medical images; display mode setting means for setting, depending on user operation, one display mode of a plurality of display modes including a first display mode for displaying the plurality of medical images and a list in which the feature amount of the identified lesion is associated for each of the medical images and a second display mode for displaying one medical image of the plurality of medical images and a graph associated with the one medical image; and display control means for controlling display of a display unit depending on the display mode set by the display mode setting means.SELECTED DRAWING: Figure 4

Description

  The present invention particularly relates to a medical image processing apparatus that displays a plurality of images obtained by photographing the same subject, a control method for the medical image processing apparatus, and a program.

  Conventionally, various medical images such as transmission radiation images, CT images, and MRI images have been widely used for examining and diagnosing living bodies such as humans. In using such a medical image, the same subject is photographed at different photographing points, for example, every month, and a plurality of images thus obtained are compared and observed, so that the time course of the lesioned part is observed. Many changes are observed. In addition, when using a plurality of images with different shooting time points regarding the same subject, and a feature amount (for example, a volume of a lesion) of a lesion portion related to each of these images for inspection / diagnosis, these can be displayed in an easy-to-see manner. desired.

  Patent Document 1 discloses a display method in which a graph showing a time series change of a tumor of a selected medical image is superimposed and displayed on an image display region of a plurality of medical images obtained by imaging the same part at different dates and times. It is disclosed.

Japanese Patent Laying-Open No. 2015-16067

  However, although Patent Document 1 displays a time-series change of a lesioned part as a graph, sufficient examination has not been made on other display methods. That is, in a medical image processing apparatus, it has been required that the user can easily present appropriate information according to the content that the user wants to diagnose or analyze the image.

  In view of the above problems, an object of the present invention is to provide a mechanism that allows a medical image processing apparatus to easily set a display method for a plurality of medical images taken at different shooting points and related information.

  In order to achieve the above object, the medical image processing apparatus of the present invention is specified from storage means for storing a plurality of medical images obtained by imaging the same part at different dates and each of the plurality of medical images. A first display mode for displaying a plurality of medical images and a list display in which the identified lesion feature values are associated with each medical image; and Display mode setting for setting one display mode among a plurality of display modes including a second display mode for displaying one medical image of the medical images and a graph relating to the one medical image in accordance with a user operation And display control means for controlling display on the display unit in accordance with the display mode set by the display mode setting means.

  According to the present invention, it is an object of the present invention to provide a mechanism that allows a medical image processing apparatus to easily set a display method for a plurality of medical images taken at different shooting points and related information.

It is a figure which shows the medical image processing system in this embodiment. It is a figure which shows the hardware constitutions of the medical image processing apparatus in this embodiment. It is a figure which shows the function structure of the medical image processing apparatus in this embodiment. It is a flowchart which shows the analysis / display process of the medical image processing apparatus in this embodiment. It is a figure which shows an example of the screen display in a comparison mode. It is a figure which shows an example of the screen display in analysis mode. It is a figure which shows an example of the screen display in database mode. It is a figure which shows an example of the screen display in database mode. It is a figure which shows the kurtosis and the skewness displayed in each mode.

  Hereinafter, this embodiment will be described in detail with reference to the drawings.

  FIG. 1 is a diagram illustrating an example of a medical image processing system 10. As shown in FIG. 1, a medical image processing system 10 includes a medical image processing apparatus 100, a modality 200, and an image server 300, and the apparatuses are connected in a communicable state via a network.

  The medical image processing apparatus 100 reads an image from the image server 300 in accordance with a request from the image interpreter and displays it on the screen. The image server 300 stores and manages an image generated by the modality 200 in an image database. The modality 200 is a medical device that generates an image of a subject. Specifically, the modality 200 is a CT apparatus, an MRI apparatus, an ultrasonic apparatus, a PET apparatus, or the like. The said form shows an example and embodiment of this invention is not limited to this. In the following description, an image generated as an example by the MRI apparatus as the modality 200 will be described.

  FIG. 2 is a diagram illustrating an example of a hardware configuration of the medical image processing apparatus 100. Note that the hardware configuration of the medical image processing apparatus 100 shown in FIG. 2 is not limited to this.

  The medical image processing apparatus 100 is a general-purpose computer such as a personal computer. The medical image processing apparatus 100 generates volume data (three-dimensional data) by stacking two-dimensional medical images (hereinafter referred to as two-dimensional medical images) obtained by tomography with a CT apparatus, MRI, or the like. . The two-dimensional medical image is a DICOM (Digital Imaging and Communication in Medicine) image. Then, it is possible to display a three-dimensional medical image (hereinafter referred to as a three-dimensional medical image) generated by performing volume rendering on the volume data. The medical image processing apparatus 100 may be a so-called personal computer or a server, but is preferably a computer specialized for processing medical images such as a workstation. Further, the medical image processing apparatus 100 may be a tablet terminal or a portable terminal that includes a touch panel.

  The CPU 101 comprehensively controls each device and controller connected to the system bus 104.

  Further, the ROM 102 or the external memory 111 stores a basic input / output system (BIOS) that is a control program of the CPU 101 and an operating system program. The external memory 111 stores various programs necessary for realizing each function. The RAM 103 functions as a main memory, work area, and the like for the CPU 101.

  The CPU 101 implements various operations by loading a program or the like necessary for execution of processing into the RAM 103 and executing the program.

  The input controller 105 controls input from an input device 109 such as a keyboard or a pointing device such as a mouse.

  The video controller 106 controls display on a display device such as the display device 110. The display device may be a CRT or a liquid crystal display device.

  The memory controller 107 controls access to the external memory 111 such as a hard disk, a flexible disk, or a card type memory connected to the PCMCIA card slot via an adapter. The external memory 111 (storage means) stores a boot program, browser software, various applications, font data, user files, editing files, various data, and the like.

  The communication I / F controller 108 is connected to and communicates with an external device via a network, and executes communication control processing on the network. For example, Internet communication using TCP / IP is possible.

  The input device 109 has a function of inputting a user operation. For example, the input device 109 is a user interface such as a mouse, a keyboard, or a touch panel.

  Note that the CPU 101 can perform display on the display device 110 by executing outline font rasterization processing on a display information area in the RAM 103, for example. Further, the CPU 101 enables a user instruction with a mouse cursor (not shown) on the display device 110.

  Various programs and the like used by the medical image processing apparatus 100 in the present embodiment to execute various processes to be described later are recorded in the external memory 111 and are executed by the CPU 101 by being loaded into the RAM 103 as necessary. Is. Furthermore, definition files and various information tables used by the program in the present embodiment are stored in the external memory 111.

  FIG. 3 is a diagram illustrating an example of a functional configuration of the medical image processing apparatus 100. Each function shown in FIG. 3 is a component realized by each hardware, various programs, etc. shown in FIG. The functional configuration of the medical image processing apparatus 100 is not limited to this.

  The medical image processing apparatus 100 includes an image data acquisition unit 301, an input reception unit 302, a storage unit 303, a lesion position acquisition unit 304, a display mode setting unit 305, and a display control unit 306.

  The image data acquisition unit 301 is a functional unit that acquires medical images (three-dimensional volume data) captured by the MRI apparatus. In the present embodiment, the image data acquisition unit 301 acquires a plurality of medical images obtained by photographing the same part at different dates and times with the modality 200. Each medical image includes a diffusion weighted image and an ADC image taken by the MRI apparatus. Here, the ADC image will be described. The ADC image is a state in which the phase of the spin immediately after application of the excitation pulse is adjusted by changing the intensity and application time of MPG (Motion Probing Gradient) in the pulse sequence of the SE method in capturing the diffusion weighted image. From the plurality of images obtained by adding the effect of the state in which the phase is diffused over time, an apparent diffusion coefficient (ADC value) is obtained and imaged. . Here, the image acquired by the image data acquisition unit 301 is stored in the storage unit 303.

  The input receiving unit 302 is a functional unit that receives user operations. For example, the input receiving unit 302 receives an input from the input device 109. The input content received by the input receiving unit 302 is stored in the storage unit 303.

  The lesion position acquisition unit 304 is a functional unit that acquires a feature amount of a lesion from an image stored in the storage unit 303. Hereinafter, processing for acquiring a feature amount of a lesion by the lesion position acquisition unit 304 will be described. Here, it is assumed that the coordinates of the diffusion weighted image and the ADC image have a correspondence relationship with each other. The high signal region (value greater than the first threshold value) in the diffusion weighted image includes a lesion and a region exhibiting a high signal due to a cause other than the diffusion phenomenon. On the other hand, a low signal region (a value smaller than the second threshold value) in the ADC image includes a lesion and a tissue having a low ADC value for other reasons. Based on these pieces of information, the lesion position acquisition unit 304 identifies, as a lesion, a region that has a high signal in the diffusion weighted image and a low signal in the ADC image. Note that the threshold is determined based on the purpose of diagnosis, the imaging region, and the like, and stored in the storage unit 303. The lesion position acquisition unit 304 acquires a feature amount of a lesion based on the identified lesion area. Here, the feature amount of the lesion includes at least one of the volume, kurtosis, and skewness of the lesion.

  Here, kurtosis and skewness will be described with reference to FIG. FIG. 9A shows the kurtosis, and FIG. 9B shows the skewness. FIG. 9C shows an example of values before and after treatment.

  The kurtosis and the skewness are indices for evaluating the malignancy of a tumor, which is calculated by three-dimensionally extracting a lesion portion in the ADC image. Further, as described above, poorly differentiated tumor cells having a high malignancy have a low ADC value, and the ADC value tends to increase as the malignancy decreases. That is, the kurtosis and the skewness are indices intended to reflect the nature of the lesion in the numerical value. As a result, it can be used to determine the effect of treatment such as chemotherapy.

  As shown in FIG. 9A, the kurtosis is a diagram showing the overall kurtosis compared with the normal distribution when the ADC value is displayed as a histogram. As shown in FIG. 9B, the skewness is a diagram showing a deviation with respect to the horizontal axis compared with the normal distribution when the ADC value is displayed as a histogram. And as shown in FIG.9 (c), by comparing the value before and behind a treatment, it is possible to use for a treatment effect determination.

  The display mode setting unit 305 is a functional unit that sets a display mode for medical images and various information related to the medical images in accordance with a user operation. Specifically, the display mode setting unit 305 sets one display mode among a plurality of display modes based on the content input by the input receiving unit 302. Note that the display mode set by the display mode setting unit 305 is stored in the storage unit 303.

  Here, the plurality of display modes include a first display mode, a second display mode, and a third display mode. In the first display mode, a plurality of medical images and a list display in which the feature quantities of the identified lesions are associated with each medical image are displayed on at least the same screen. In the present embodiment, the first display mode is referred to as a comparison mode. The comparison mode is a display mode for the purpose of easily comparing a plurality of medical images obtained by photographing the same part at different dates and times with a modality 200 (for example, an MRI apparatus).

  The second display mode is a display mode for displaying one medical image of a plurality of medical images and a graph related to the one medical image. In the present embodiment, the second display mode is referred to as an analysis mode. The analysis mode is a display intended to analyze one medical image in more detail by displaying one medical image and a graph among a plurality of medical images obtained by photographing the same part at different dates and times. Mode.

  The third display mode is a display mode in which a plurality of medical images, the above-described graph, and a comment input field for one medical image among the plurality of medical images are displayed on the same screen. In the present embodiment, the third display mode is referred to as a database mode. The database mode is a display mode in which changes in a plurality of medical images in time series can be confirmed, and comparison of a plurality of images and detailed information (including input comments) of the plurality of images can also be confirmed. The display screen displayed in each display mode will be described later with reference to FIGS.

  The display control unit 306 is a functional unit that controls the screen displayed on the display device 110 (display unit) based on the display mode set by the display mode setting unit 305. In the present embodiment, the display control unit 306 includes a plurality of medical images, a list display in which the feature amounts of the lesions identified by the lesion position acquisition unit 304 are associated with each medical image, and an operation screen for the plurality of medical images. Are displayed on the display device 110. Here, the list display is a display for each lesion identified by the lesion position acquisition unit 304. The specific screen display controlled by the display control unit 306 will be described later with reference to FIGS.

  Next, a flow showing analysis / display processing of the medical image processing apparatus 100 according to the present embodiment will be described with reference to FIG. The following controls are executed by the functional units of the medical image processing apparatus 100.

  In step S401, the image data acquisition unit 301 acquires a current image. Specifically, the image data acquisition unit 301 acquires a diffusion weighted image and an ADC image that are captured at a predetermined date and time.

  In S402, the image data acquisition unit 301 acquires a past image. Specifically, the image data acquisition unit 301 acquires a diffusion weighted image and an ADC image that are captured at a date and time before the image acquired in S401.

  In S403, the lesion position acquisition unit 304 acquires the current lesion position using the diffusion weighted image and the ADC image acquired in S401 and S402. That is, the feature amount of the lesion is acquired by being specified from each of a plurality of medical images (a diffusion-weighted image and an ADC image, which are current images, and a diffusion-weighted image and an ADC image of past images).

  In S404, the input receiving unit 302 receives the display mode selected by the user's operation.

  In step S <b> 405, the display mode setting unit 305 sets one display mode among a plurality of display modes based on the content input by the input receiving unit 302. If the display mode is the comparison mode, the process proceeds to S406. If the display mode is the analysis mode, the process proceeds to S407. If the display mode is the database mode, the process proceeds to S409. .

  In S406, S407, and S409, the display control unit 306 generates a list to be displayed on the display unit based on the lesion position and feature amount acquired by the lesion position acquisition unit 304.

  In S <b> 408 and S <b> 410, the display control unit 306 generates a graph to be displayed on the display unit based on the lesion position and feature amount acquired by the lesion position acquisition unit 304.

  In step S411, the display control unit 306 generates a medical image in which the position of the lesion acquired by the lesion position acquisition unit 304 is superimposed on a plurality of medical images.

  In step S412, the display control unit 306 controls to display the generated screen on the display unit.

  Next, the display screen in each display mode will be described in detail with reference to FIGS. FIG. 5 is a diagram illustrating an example of a screen display in the comparison mode. FIG. 6 is a diagram illustrating an example of a screen display in the analysis mode. 7 and 8 are diagrams showing examples of screen display in the database mode.

  The comparison mode display screen 500 will be described with reference to FIG. The comparison mode display screen 500 includes display items (501 to 503) for selecting and displaying the display mode. The display item related to the currently selected display mode is displayed in a manner distinguishable from other display items. In the present embodiment, the display item 501 indicates that the display item 501 is selected by changing the display color. Thus, by providing a display item for selecting a display mode on the same screen, the user can quickly and easily change the display mode according to the diagnosis content.

  The list display 510 is a data table showing a list of feature amounts of lesions in past images. ID511 is identification information for identifying a lesion. The volume 512 is a value indicating the volume of each lesion. The kurtosis 513 is a value indicating the kurtosis of each lesion. The skewness 514 is a value indicating the skewness of each lesion. The list display 510 displays the volume, kurtosis, and skewness corresponding to the total value of each lesion. That is, the list display 510 is an example of a data table in which identification information (ID511) for identifying lesions and feature amounts (512 to 514) are associated with each other.

  The list display 530 is a data table showing a list of feature amounts of lesions in the current image. Note that the contents of each item in the list display 530 are the same as those in the list display 510, and thus description thereof is omitted.

  The past image 520 is a medical image in which the position of the lesion acquired by the lesion position acquisition unit 304 is superimposed on the past medical image. Here, the lesions 521 to 523 superimposed on the past image 520 correspond to the lesions displayed on the list display 510.

  The current medical image 540 is a medical image in which the position of the lesion acquired by the lesion position acquisition unit 304 is superimposed on the medical image acquired by the image data acquisition unit 301. The past image 520 and the current medical image 540 displayed here are, for example, MIP (Maximum Intensity Projection) images of three-dimensional volume data. Alternatively, the past image 520 and the current medical image 540 may be MPR (Multi Planar Reconstruction) images.

  Further, the lesions 521 to 523 are displayed in a manner that can identify whether the lesions 521 to 523 correspond to the lesions 541 to 542 of the current medical image 540. In FIG. 5, as an example, the lesion 521 and the lesion 541 are displayed in a different color from the other lesions. For this reason, the user can easily identify the correspondence between these lesions. In addition, the display control unit 306 can display only the associated lesions in a graph when displaying a graph indicating changes in the time series of lesions in other display modes described later. These associations can be realized by selecting lesions to be associated with the list display 510 and the list display 530. Further, this can be realized by selecting lesions to be associated with the past image 520 and the current medical image 540.

  The past data selection unit 550 is an operation unit that selects data to be read from a plurality of past images.

  The image operation unit 560 is an operation unit for performing operations such as image enlargement / reduction, measurement, and finding entry.

  Here, the layout of each component in the comparison mode display screen 500 will be described. The display control unit 306 displays a plurality of medical images and an operation screen on the display unit in the first direction. Further, the display control unit 306 arranges a plurality of medical images (520, 540) and a list display (530, 550) corresponding to each of the plurality of medical images in a second direction orthogonal to the first direction. indicate. Further, the display control unit 306 displays a plurality of list displays (530, 550) side by side in the first direction. Here, the first direction is the horizontal direction on the comparison mode display screen 500, and the second direction is the vertical direction on the comparison mode display screen 500. In particular, since a plurality of medical images and a list display, which are the same type of information, are arranged in the horizontal direction, the comparison becomes easy. That is, when a user diagnoses a medical image, the frequency of moving the line of sight between a plurality of medical images or list displays is relatively high. On the other hand, since the medical image and the list display are information (medical image) used mainly in diagnosis and the detailed information (list display), the frequency of moving the line of sight is relatively low. This is the reason why the layout of the comparison mode display screen 500 is suitable. The display control unit 306 displays a plurality of medical images and the list display side by side so as not to overlap each other. By “not superimposing”, it is possible to display on one screen while improving visibility.

  Next, an example of screen display in the analysis mode will be described with reference to FIG. Note that the description of the analysis mode display screen 600 in FIG. 6 with the same number as in FIG. 5 is omitted. 6 correspond to 530, 540, and 560 in FIG. 5, respectively.

  The analysis mode display screen 600 includes a list display 610 and current medical images 630 and 640 displayed at a plurality of angles. A histogram 620 is a graph showing a histogram of a lesion selected from the list display 610. The current medical image 630 is a cross-sectional view showing a specific cross section of the current medical image 640. In the present embodiment, a histogram is used as an example of a graph. However, the present invention is not limited to this. For example, a bar graph or a line graph may be used. Thus, in the analysis mode, one medical image can be analyzed in more detail by displaying one medical image on one screen without superimposing the medical image, the list display, and the graph.

  The extraction condition setting unit 650 is an operation unit that sets conditions for specifying the position of a lesion by the lesion position acquisition unit 304. The extraction condition setting unit 650 includes a position acquisition operation execution button 651, a DWI threshold value setting input field 652 for setting a threshold value of a diffusion weighted image, and an ADC threshold value setting input field 653 for setting a threshold value of an ADC image. In response to selection of the position acquisition operation execution button 651, the lesion position acquisition unit 304 acquires the feature amount of the lesion using the input threshold value. In particular, the extraction condition setting unit 650 is preferably used when the user manually acquires a lesion position again after an automatic lesion position.

  Next, the database mode display screen 700 will be described with reference to FIG. Note that the description of the database mode display screen 700 of FIG. A database mode display screen 700 in FIG. 7 includes a graph 710 showing changes in a time series of lesions displayed in a list display, unlike FIG. Here, the screen layout in the database mode display screen 700 will be described. The display control unit 306 displays the graph 710 side by side in the second direction so as not to overlap with the plurality of medical images (520, 540) and the list display (510, 530). The graph 710 and the list display are preferably arranged so as to be adjacent to each other. This is because the user often moves his / her line of sight between the list display (510, 530) and the graph 710. As described above, the display control unit 306 may display a time-series change of only the lesion associated as the graph 710. Further, the display control unit 306 may display only the total value, not the change of each lesion. As described above, it is possible to display the medical image and the feature amount of the lesion at each time point while displaying the time-series change between the plurality of medical images as a graph.

  Next, the database mode display screen 800 will be described with reference to FIG. The database mode display screen 800 is a screen that displays an input field for a comment associated with the current medical image 540 on the database mode display screen 700. In the comment input field 720, as an example, information on medicines administered before and after the date and time when the current medical image 540 is taken is input. Here, the screen layout in the database mode display screen 800 will be described. The display control unit 306 displays one medical image 540 of the plurality of medical images (520, 540) and the comment input field 720 in the first direction so as not to overlap and not overlapping. The comment input field 720 also has a function as a comment display field for displaying the input comment. In this way, by displaying medical images, comments, list display, and graphs on a single screen without overlapping, it is possible to confirm the change in the feature amount between the medical images, and also to have the therapeutic effect of the medicine administered between them. It becomes possible to consider at the same time.

  As described above, according to the present embodiment described above, the display control unit 306 performs control so that a plurality of medical images and an operation screen are displayed side by side in the first direction, and the plurality of medical images and the plurality of medical images are displayed. Control is performed so that the list display corresponding to each of the images is displayed side by side in a second direction orthogonal to the first direction. For this reason, it becomes possible to improve the visibility when displaying lesions corresponding to a plurality of medical images photographed at different photographing points.

  Further, according to the present embodiment described above, the display mode setting unit 305 displays the first display mode that displays a plurality of medical images and a list display in which the identified feature amounts of the lesions are associated with each medical image. And one display mode among a plurality of display modes including a second display mode for displaying one medical image of the plurality of medical images and a graph relating to the one medical image is set according to a user operation. be able to. Therefore, it is possible to provide a mechanism capable of easily setting a display method for a plurality of medical images and related information taken at different photographing points.

  Each embodiment can also be realized by a computer or a control computer executing a program (computer program). Further, means for supplying a program to a computer, for example, a computer-readable recording medium such as a CD-ROM recording such a program, or a transmission medium such as the Internet for transmitting such a program can also be applied as an embodiment. . The above program can also be applied as an embodiment. The above program, recording medium, transmission medium, and program product are included in the scope of the present invention.

  As mentioned above, although it explained in full detail based on embodiment, it is not restricted to these specific embodiment, Various forms of the range which does not deviate from the summary of invention are also included in the category of this invention. Furthermore, the above-described embodiment is merely an embodiment, and an invention that can be easily imagined from the above-described embodiment is also included in the scope of the present invention.

DESCRIPTION OF SYMBOLS 100 Medical image processing apparatus 301 Image data acquisition part 302 Input reception part 303 Storage part 304 Lesion position acquisition part 305 Display mode setting part 306 Display control part

Claims (8)

Storage means for storing a plurality of medical images obtained by photographing the same part at different dates and times;
Obtaining means for obtaining a feature amount of a lesion identified from each of the plurality of medical images;
A first display mode for displaying the plurality of medical images and a list display in which feature quantities of the identified lesions are associated with each medical image; one medical image of the plurality of medical images; Display mode setting means for setting one display mode among a plurality of display modes including a second display mode for displaying a graph relating to a medical image of the user according to a user operation;
A medical image processing apparatus comprising: display control means for controlling display of the display unit in accordance with the display mode set by the display mode setting means.   The display mode setting means includes a plurality of display modes including a third display mode for displaying the plurality of medical images, the graph, and a comment input field for one medical image of the plurality of medical images. The medical image processing apparatus according to claim 1, wherein one of the display modes is set according to a user operation.   The medical image processing apparatus according to claim 1, wherein the list display is further displayed in the second display mode.   The medical image processing apparatus according to any one of claims 1 to 3, wherein the medical image is an image captured by an MRI apparatus. The feature amount includes at least one of the volume, kurtosis, and skewness of the lesion,
The medical image processing apparatus according to claim 1, wherein the list display associates identification information for identifying the lesion with a feature amount. The list display includes a plurality of feature quantities of the lesions,
The medical image processing apparatus according to claim 1, wherein the display control unit displays a total value of feature amounts of the plurality of lesions. A control method for a medical image processing apparatus having a storage means for storing a plurality of medical images obtained by imaging the same part at different dates and times,
An acquisition step of acquiring a feature amount of a lesion identified from each of the plurality of medical images;
A first display mode for displaying a list display in which the plurality of medical images and feature quantities of the identified lesion are associated with each medical image; and the plurality of medical images and feature quantities of the identified lesion A display mode setting step of setting one display mode among a plurality of display modes including a second display mode for displaying a graph showing changes in time series of
And a display control step of controlling display of the display unit in accordance with the display mode set in the display mode setting step.   A computer program for causing a medical image processing apparatus to function as each means of claims 1 to 6.

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