JP2008512161A - User interface for CT scan analysis - Google Patents

Abstract

  The original scan image and the enhanced scan image derived from the original scan image are displayed side by side or alternately so as to simplify the comparison between the original image and the enhanced scan image. The user changes the enhancement parameters of the enhanced image while viewing the original image and the enhanced scan image, observes the effect on the enhanced image, and compares it with the analysis of his / her original image. You can adjust the parameters to the settings. The adjusted parameters can be applied to other parts of the original image to provide a more accurate analysis.

Description

  The present invention relates to a user interface for CT scan analysis, and more particularly to a user interface that displays a computed tomography (CT) scan image that highlights potential lesions or other anomalies.

  In conventional analysis of CT images, the radiologist visually inspects each slice of the CT scan with the expertise to identify anomalies and distinguish them from normal structures. The task can be performed more easily by storing the scanned image on a computer and providing a user interface that allows the user to quickly move between slices and visualize the structure in various ways. However, the process is time consuming and great care must be taken not to overlook the anomalies.

To replace some or all of the radiologist's work, computer-aided detection (CAD) software is designed to analyze the scanned image and detect potential lesions. Detection can be done automatically by interaction with the radiologist or automatically without interaction beyond selection of the image to be analyzed. For example, Applicants' MedicalHeart (R), MedicLung (R), and Medicron (R) diagnostic software each semi-automatically diagnose heart, lung, and colon CT scans.
International Publication No. 03/072033 Pamphlet US Pat. No. 6,058,322

  In practice, CAD must be checked by a radiologist as a safety measure. When the software is used as a “first reader”, the radiologist only checks the results generated by the software and does not analyze the original CT scan. Because the radiologist can make important decisions medically based on the results, in order to be effective as a “first leader”, the software has high sensitivity (ie, a low percentage of lesions that are overlooked). Must have both high specificity (ie, low rate of false prevalence). While the “first reader” has the greatest potential to save the radiologist's time, achieving both high sensitivity and specificity is a major challenge.

  Alternatively, the software can also be used as a “second reader”, in which case the radiologist makes a preliminary diagnosis entirely based on the original image and then uses the software to check for missed lesions. Make it work. When used as a “second reader”, the software does not actually save time, but helps the radiologist to make a better diagnosis. The software need not be particularly sensitive or specific as long as it leads to a more accurate decision than an unsupported radiologist. When used in this way, the software is similar to a word processor spelling or grammar checker, and it only draws the user's attention to the oversight, rather than replacing the user's actions.

  It would be desirable to create a user interface for an analytical CT scan that does not need to be as accurate as the “first reader” software and saves time over the “second reader” software.

  Patent Document 1 discloses a user interface that can display corresponding areas from different scans side by side.

  Another problem is that many CAD algorithms rely on a predetermined set of parameter ranges for detection. For example, the Agaston method first described in “Quantification of coronary artery calcification using ultrafast computed tomography”, Agaston AS, Janowitz WR, Hildner FJ et al., J Am Coll Cardol 1990 15: 827-832 A field value (HU) threshold is applied to the CT image and all pixels that exceed the threshold are identified as containing calcium. A scoring system is then used to evaluate the severity of the calcification based on a number that exceeds the threshold multiplied by a weighted value based on the highest intensity in the calcification. When the maximum intensity is 130 to 200 HU, the weight value is 1. When 200 to 300 HU, the weight value is 2, and when it exceeds 300 HU, the weight value is 3. The thresholds and weights are based on field studies of the patient's coronary scan and subsequent results. However, there is ongoing debate as to whether this parameter range will yield the most accurate results. Different ranges may be appropriate for different scanned images.

  Patent Document 2 discloses an interactive user correction function that allows software to display detected microcalcifications and then allow a user to add or delete microcalcifications. Therefore, the software corrects the probabilities of malignancy.

  According to one aspect of the invention, a CT scan image display method is proposed that includes displaying an original scan image and displaying an enhanced scan image derived from the original scan image. Preferably, the original image and the emphasized scan image are displayed with similar image characteristics such as size and scale in order to simplify comparison between the two. The enhanced image can be enhanced to identify a user's lesion or anomaly in the original image.

  In one embodiment, the original image and the enhanced scan image are displayed simultaneously. In another embodiment, the original image and the enhanced scan image are displayed alternately with similar dimensions, scales, and positions. The original image and the emphasized scan image are preferably displayed on the same display device.

  The advantage of such an arrangement is that the enhanced image can be visually checked against the enhanced image without obscuring the features of the original image. Instead of using the enhanced image as the first or second reader, the enhanced image serves as a co-leader for users who examine the original image while using the enhanced image as an auxiliary function.

  In one embodiment, the user can change the enhancement parameters of the enhanced image while viewing the original image and the enhanced scan image. In this way, the user can observe the effect on the enhanced image and adjust the parameters to the most appropriate settings for the image while comparing with the analysis of his original image. The adjusted parameters can be applied to other parts of the original image to provide a more accurate analysis.

  Specific embodiments of the present invention will be described below with reference to the accompanying drawings.

Scanned Image A CT image includes one or more slices obtained from a human or animal patient using a CT scanner. Each slice is a two-dimensional digital tone image of X-ray absorption of the scanned area. The slice characteristics depend on the CT scanner used. For example, a high resolution multi-slice CT scanner can produce an image of 0.5 to 0.6 mm / pixel in the X and Y directions (ie, on the slice plane). Each pixel can have a 32-bit gradation resolution. The intensity value of each pixel is usually represented by a Hounsfield value (HU). Successive slices can be separated along the Z direction (ie, scan separation axis) at regular intervals, eg, 0.75 to 2.5 mm. Thus, the scanned image may be a two-dimensional (2D) or three-dimensional (3D) grayscale image having an overall size depending on the area and number of scanned slices.
The present invention is not limited to a specific scanning technique, but can be applied to electron beam computed tomography (EBCT), multi-detector or spiral scanning, or a technique for generating an output 2D or 3D image representing X-ray absorption. .

Computer System As shown in FIG. 1, a scan image is created by a computer 4 that receives scan data from the scanner 2 and constructs the scan image. The scanned image is stored as an electronic file or file series stored in a storage medium 6 such as a fixed or removable disk. Scanned images can be saved in a standard format such as DIRCOM 3.0. The scanned image can be processed by the computer 4, or the scanned image can be transferred to another computer 8 that executes software to process and display the image as described below. The software can be stored on a carrier such as a removable disk or downloaded over the network.

User Interface Flowchart FIG. 2 shows a flowchart of a user interface operation method executed by software in the embodiment of the present invention. The original scan image is provided as input (S1) and processed to provide an enhanced scan image (S2). The original scan image and the emphasized scan image are displayed side by side or alternately with the display of the parameter values used for enhancement (S3). If a user input is accepted for adjustment of the parameter value (S4), the parameter value is adjusted (S5), and an enhanced scan image is generated again using the adjusted parameter (S2).

  The original image and the emphasized scan image can be displayed side by side at the same position, size, and scale, or can be displayed alternately. For example, image enhancement can be switched alternately. Switching between the original image and the emphasized scan image can be performed every time the user presses a specific key or clicks a button on the screen.

Lung Scan Embodiment FIG. 3 shows a two-dimensional slice of a scan of a lung model (ie, a model that includes a subject that approximates the lung and has known properties used for examination and correction). FIG. 2 shows a screenshot of a user interface of one embodiment.

  The user interface is shown in a window that includes the original image panel 10 and the enhanced image panel 12. The original image panel 10 displays a slice of the scanned image. The first toolbar 18 is disposed on the bottom surface of the original image panel 10 and includes buttons that allow the user to operate the original image by zooming, panning, rotation, and the like, for example. The original image panel 10 also includes a first scroll bar 22 that allows the user to move back and forth between slices.

  The enhanced image panel 12 displays a version of the original image that has been processed by one or more filters to enhance features of the original image. In this example, a sphericity enhancement filter is applied, and a target that satisfies the sphericity filter is surrounded by a circle. The second toolbar 20 in the enhanced image panel 12 includes buttons that allow the user to operate the enhanced image by, for example, zooming, panning, rotation, and the like. The enhanced image panel 12 also includes a second scroll bar 24 that allows the user to move back and forth between slices.

  The first and second toolbars 18, 20 can be linked so that the image manipulation performed by either toolbar corresponds to or has an equivalent effect on both the original image and the enhanced scan image. For example, when the original scan image is enlarged using the first toolbar 18, the enhanced scan image is enlarged by the same amount in the enhanced image panel 12. In another example, when the enhanced scan image is enlarged using the second toolbar 20, the original scan image is enlarged by the same amount in the original image panel 10. In this way, a parallel comparison between the same images of the original image and the emphasized scan image becomes possible.

  The first and second scroll bars 22, 24 can be linked so that the movement of either scroll bar corresponds to both the original image and the enhanced scan image, or has an equivalent effect. Thereby, the user can move back and forth in the Z direction while comparing the original image and the emphasized scan image.

  The user interface window includes a right hand toolbar 14 that displays various options that the user can select. The “Display” option allows the user to control how many panels, such as 1, 2, 4, etc., are displayed, or which panels are displayed as separate windows. In this example, only two panels are used to display a scanned image, and a data display function and a 3D nodule display function are assigned to the third and fourth panels, respectively.

  Filter types and parameters are controlled by the user using a filter window 16 shown in greater detail in FIG. In this example, the user can select one of a sphericity enhancement filter, an edge filter, a standard noise removal filter, and an enhancement noise removal filter by selecting the corresponding tab. Thereafter, the user sets the parameter value of the filter and clicks a button for applying the filter to update the emphasized image.

Sphericality enhancement filter In this example, the sphericity enhancement filter tab includes a sphericity slider 26 that allows the user to set the minimum sphericity level of the object that passes the filter, and the minimum and maximum peak intensities within the object that pass the filter. Includes a minimum intensity slider 28a and a maximum intensity slider 28b, and a nodule dimension selector 30 that allows the user to select one from a plurality of dimension ranges to be passed through the filter. The user can select a first option 32 for detecting a plurality of micro-nodules and a second option 34 for removing a cylindrical shape. The latter provides the user with the ability to avoid the enhancement of spherical shapes in cylindrical structures such as blood vessels.

  The sphericity enhancement filter analyzes each body element (voxel) in the scanned image and derives a three-dimensional curvature of equal intensity compared to surrounding voxels of similar intensity. A surface having a sphericity exceeding the level selected by the user is identified as belonging to spherical symmetry. Next, the voxels contained in those planes are grouped together as part of the same object. Once all of the above objects are identified, the filter highlights objects having a maximum intensity between the minimum and maximum values selected by the user and dimensions within a range selected by the user.

  If a spherical object passing through the filter occupies a plurality of consecutive slices, the object can be emphasized only on slices that occupy the maximum area of the object.

Edge Enhancement Filter FIG. 5 shows an embodiment where an edge enhancement filter is selected and applied and applied to another scanned image. Edge enhancement is applied only to the lung parenchyma region and is advantageous for identifying signs of interstitial disease such as reticulated shadows.

  When the edge enhancement filter is selected, a contrast setting window 36 is displayed so that the user can change the contrast parameter of the edge enhancement filter.

Standard Noise Removal Filter FIG. 6 shows the filter window 16 when the standard noise removal filter is selected. The filter window displays a blur slider 38 that allows the user to change the noise smoothing level. This filter is useful for interpreting low-dose multi-slice helical CT (MSCT) studies, where radiation dose reduction is realized at the expense of increased background noise. The standard noise removal filter smoothes the background noise to the extent set by the user.

Advanced Noise Removal Filter FIG. 7 shows the filter window 16 when the advanced noise removal filter is selected. The filter window 16 displays a window size selector 40 that sets the size of the window used by the advanced noise reduction method. Using this approach, blurring is clearly reduced over the standard approach, but takes longer.

Colon Scan Embodiment FIG. 8 shows a screen display of the user interface of the second embodiment for use in a scan image of the large intestine. This embodiment differs from the lung scan embodiment in the type of filter available. Single polyp enhancement filters are available in addition to the filter options used in lung scan embodiments. However, any filter available in the lung scan embodiment can be used in the second embodiment. Similar parts are denoted by the same reference numerals, and redundant description will not be given.

  The filter window 16 displays settings for a polyp enhancement filter that emphasizes raised objects with spherical elements, but does not emphasize objects that are likely to become elongated wrinkles. The filter window includes minimum and maximum flatness sliders 38a, 38b that allow the user to select the flatness of the object to be emphasized.

  In this example, the third and fourth panels include the second original image panel 40 and the second emphasized image panel 42, and display an image in the axial direction facing the back of the scanned image, while the original image panel 10 and The emphasized image panel 12 displays an image of the prone axial direction. The operations of displaying the second original image panel 40 and the second emphasized image panel 42 are linked so that changes made in one panel are reflected in another panel.

Single Video Embodiment As an alternative to the parallel video described above, the user can select a display mode in which only one scanned image video is displayed in the user interface window. The emphasis selected by the filter window can be turned on and off, for example, by switching a button on the filter window. When switching between the original image and the enhanced image so that the user can easily compare the enhanced image with the original image, the image display parameters remain unchanged.

Other Embodiments The embodiments described above are intended to illustrate rather than limit the invention. Embodiments that are obvious after reading the above description are included in the scope of the present invention.

FIG. 2 is a schematic diagram illustrating a CT scanner and a remote computer that processes image data from the scanner and operates a user interface. 6 is a flowchart showing the main method steps of operation of the user interface of an embodiment of the present invention. It is a screen shot figure of a user interface to which a sphericity emphasis filter is applied. It is a figure which shows the filter window of a user interface by which the sphericity emphasis filter was selected. It is a screen shot figure of a user interface to which an edge emphasis filter was applied. It is a figure which shows the filter window from which the standard noise removal filter was selected. It is a figure which shows the filter window from which the advanced noise removal filter was selected. It is a screen shot figure of the user interface of a 2nd embodiment for using with a colon scan image.

Claims (15)

a) The original scan image is processed in order to generate an enhanced image that emphasizes one or more features indicating anomalies in the original scan image and darkens at least one other feature of the original scan image (S2) In a computer-implemented method for displaying a computed tomography (CT) scan image, comprising:
b) displaying the original scan image and the emphasized scan image so that the two can be visually compared (S3).   The method of claim 1, wherein the original scan image (10) and the enhanced scan image (12) are displayed simultaneously.   2. The method of claim 1, wherein the original scan image and the enhanced scan image are displayed alternately.   4. The method of claim 3, wherein the display is alternated between the original scan image and the enhanced scan image in response to user input.   5. The method according to claim 3, wherein the original scan image and the emphasized scan image are alternately displayed at substantially the same position.   The display image (10) of the original scan image and the display image (12) of the emphasized scan image are modified (S5) according to a user input (S4). One way. The display image (10) of the original scan image is a slice image of the original scan image,
The display image (12) of the emphasized scan image is a slice image of the corresponding emphasized scan image,
7. The method of claim 6, wherein the display slice image of the original scan image and the corresponding slice image of the enhanced scan image are modified in response to user input. Performing the processing step (S2) according to one or more user-defined parameters;
Accepting user input to modify the one or more parameters;
8. The method of any one of the preceding claims, comprising performing a processing step and a displaying step using the modified one or more parameters. The processing step is performed by selecting one of a plurality of filters.
Accepting user input to select one of the filters;
9. A method as claimed in any one of the preceding claims, comprising performing a processing step and a display step using the selected filter.   10. The method according to claim 1, wherein the original scan image is a lung scan image, and the original scan image is processed (S2) to enhance spherical objects in the enhanced scan image.   11. The method according to claim 1, wherein the original scan image is a lung scan image, and the original scan image is processed (S2) to enhance edges in the enhanced scan image.   The original scan image is a scan image of the large intestine, and the original scan image is processed (S2) to enhance a spherical object raised from the colon wall of the emphasized scan image (S2). One way.   A computer program configured to execute the method of any one of claims 1-12.   A computer program product recorded on a carrier and comprising the computer program of claim 13. a) Emphasizing one or more features that indicate anomalies in the original scan image and configured to process the original scan image to generate an enhanced image that darkens at least one other feature of the original scan image Means,
b) An apparatus (8) for displaying a computed tomography (CT) scan image comprising means configured to display an original scan image and an enhanced scan image so that a visual comparison of the two is possible.

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