Medical image processing device, medical image processing program, and medical image processing method

Abstract

To improve visibility of a contrast area.SOLUTION: A medical image processing device includes an acquisition part, a threshold processing part, a setting part, and a synthesis part. The acquisition part acquires a contrast image on a subject, and a subtraction image generated by a difference between a non-contrast image on the subject and the contrast image. The threshold processing part performs threshold processing using a threshold on the contrast for the subtraction image, and generates a threshold processing image. The setting part sets a start point and a search direction to the threshold processing image, and sets a contrast enhancement area for enhancing a brightness value of the contrast in the contrast image on the basis of the start point and the search direction. The synthesis part generates a composite image by synthesizing the threshold processing image, the contrast enhancement area, and the contrast image on the basis of the positioning between the contrast image and the threshold processing image.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The embodiments disclosed in this specification and the drawings relate to a medical image processing apparatus, a medical image processing program, and a medical image processing method.

Background Art

[0002] Conventionally, multiple-phase imaging has been clinically performed to grasp the flow of blood and the structure of tumors by administering a contrast agent. At this time, there may be cases such as a deviation in the imaging timing and poor staining of the contrast agent, and the resulting contrast image may not be the desired image. On the other hand, as a technique for generating an image having a higher luminance value only for the contrast region, there is a method of adding a subtraction image to the contrast image.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to improve the visibility of the contrast region. However, the problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above problems. The problems corresponding to the respective effects of the respective configurations shown in the embodiments described later can also be regarded as other problems.

Means for Solving the Problems

[0005] The medical image processing apparatus according to this embodiment includes an acquisition unit, a threshold processing unit, a setting unit, and a synthesis unit. The acquisition unit acquires a contrast image regarding a subject, a non-contrast image regarding the subject, and a subtraction image generated by the difference between the contrast image and the non-contrast image. The threshold processing unit performs threshold processing on the subtraction image using a threshold regarding contrast to generate a threshold processed image. The setting unit sets a starting point and a search direction for the threshold processed image, and sets a contrast enhancement region for enhancing the luminance value of the contrast in the contrast image based on the starting point and the search direction. The synthesis unit generates a synthesized image by synthesizing the threshold processed image, the contrast enhancement region, and the contrast image based on the alignment of the contrast image and the threshold processed image.

Brief Description of the Drawings

[0006]

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DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, embodiments of a medical image processing apparatus, a medical image processing program, and a medical image processing method will be described with reference to the drawings. In the following embodiments, parts denoted by the same reference numerals perform the same operations, and redundant descriptions will be omitted as appropriate.

[0008] (Embodiment) FIG. 1 is a block diagram showing an example of the configuration of a medical image processing system 1 including a medical image processing apparatus 30 according to an embodiment. As shown in FIG. 1, the medical image processing system 1 according to the embodiment includes an X-ray computed tomography (CT) apparatus 10, an image storage apparatus 20, and a medical image processing apparatus 30. As shown in FIG. 1, the X-ray CT apparatus 10, the image storage apparatus 20, and the medical image processing apparatus 30 are interconnected via a network.

[0009] The X-ray CT apparatus 10 collects projection data by irradiating a subject with X-rays. For example, the X-ray CT apparatus 10 generates an X-ray CT image (hereinafter referred to as a CT image) by collecting and reconstructing projection data from the subject. The X-ray CT apparatus 10 transmits the generated CT image to the image storage apparatus 20 or the medical image processing apparatus 30. Since a known configuration can be applied as the configuration of the X-ray CT apparatus 10, the description thereof will be omitted. The X-ray CT apparatus 10 is an example of an image capturing apparatus.

[0010] CT images include contrast images, non-contrast images, and subtraction (difference) images. The contrast images are generated by an X-ray CT scan after injection of a contrast agent into a subject. The non-contrast images are generated, for example, by an X-ray CT scan of the same imaging site as the X-ray CT scan for the contrast images. Since known methods are applicable to the X-ray CT scans for contrast and non-contrast, the description thereof is omitted. The subtraction images are generated by the difference between the non-contrast images and the contrast images. The subtraction images are generated, for example, by subtracting the non-contrast images from the contrast images after alignment of the contrast images and the non-contrast images. Since known methods are applicable to the generation of the subtraction images, the description thereof is omitted. The CT images are, for example, three-dimensional volume data, a plurality of two-dimensional image data along a specific direction such as the axial direction, etc. Hereinafter, for the sake of specific description, the CT images will be described as being volume data.

[0011] The image storage device 20 stores CT images generated by the X-ray CT device 10 and the like. For example, the image storage device 20 is realized by a computer device such as a server device. Specifically, the image storage device 20 is realized by a PACS (Picture Archiving and Communication System) server or the like. The image storage device 20 may be referred to as a medical image management system. In the present embodiment, the image storage device 20 acquires CT images from the X-ray CT device 10 via a network, and stores the acquired CT images in a memory and / or a storage provided inside or outside the device.

[0012] The medical image processing apparatus 30 acquires CT images from the X-ray CT apparatus 10 or the image storage apparatus 20 via a network, and executes various image processes based on the acquired CT images. The medical image processing apparatus 30 may be referred to as a medical image analysis apparatus or the like. For example, the medical image processing apparatus 30 is realized by a computer device such as a workstation. Note that various functions realized by the medical image processing apparatus 30 may be executed by various applications or the like in a server apparatus or the like in the image storage apparatus 20. At this time, the medical image processing apparatus 30 corresponds to the server apparatus in the image storage apparatus 20. Further, the medical image processing apparatus 30 causes the display 32 to display the result of the process processed based on the CT image.

[0013] As shown in FIG. 1, the medical image processing apparatus 30 includes an input interface 31, a display 32, a memory 33, and a processing circuit 34.

[0014] The input interface 31 is realized by a trackball, a switch, a button, a mouse, a keyboard, a touch pad that performs an input operation by touching an operation surface, a touch screen in which a display screen and a touch pad are integrated, a non-contact input circuit using an optical sensor, or the like for performing various instructions and various settings. The input interface 31 converts the input operation received from the operator into an electrical signal and outputs the electrical signal to the processing circuit 34. Note that the input interface 31 is not limited to those including physical operation components such as a mouse and a keyboard. For example, an electrical signal processing circuit that receives an electrical signal corresponding to an input operation from an external input device provided separately from the medical image processing apparatus 30 and outputs this electrical signal to the processing circuit 34 is also included in the example of the input interface 31. The input interface 31 is an example of an input unit.

[0015] The display 32 displays various types of information under the control of the display control function 34e. For example, the display 32 displays a GUI (Graphical User Interface) for receiving an operator's instructions and a two-dimensional CT image generated based on volume data. For example, the display 32 is a liquid crystal display or a CRT (Cathode Ray Tube) display. The display 32 is an example of a display unit.

[0016] The memory 33 is realized by, for example, a semiconductor memory element such as a RAM (Random Access Memory) or a flash memory, a hard disk, an optical disk, etc. For example, the memory 33 stores a CT image obtained from the X-ray CT apparatus 10 or the image storage apparatus 20. Also, for example, the memory 33 stores a program for each circuit included in the medical image processing apparatus 30 to realize its function. The memory 33 is an example of a storage unit.

[0017] The processing circuit 34 controls the operation of the entire medical image processing apparatus 30 by executing an acquisition function 34a, a threshold processing function 34b, a setting function 34c, a synthesis function 34d, and a display control function 34e.

[0018] The processing circuit 34 reads out and executes a program corresponding to the acquisition function 34a from the memory 33 to acquire a CT image from the X-ray CT apparatus 10 or the image storage apparatus 20. Specifically, the acquisition function 34a acquires a contrast image regarding the subject and a subtraction image generated by the difference between the non-contrast image regarding the subject and the contrast image. Note that the acquisition function 34a may further acquire a non-contrast image in addition to the contrast image and the subtraction image. The processing circuit 34 that realizes the acquisition function 34a is an example of an acquisition unit.

[0019] The processing circuitry 34 reads out from the memory 33 a program and a threshold value corresponding to the threshold processing function 34b and executes them. The threshold value is a threshold value related to contrast, and is set in advance and stored in the memory 33. Specifically, the threshold value is a value used to distinguish a contrast-enhanced region in a subtraction image, and is a value indicating a predetermined brightness value that assumes the brightness value of the contrast-enhanced region. Based on these, the threshold processing function 34b performs threshold processing using the threshold value on the subtraction image to generate a threshold-processed image. The threshold processing function 34b stores the generated threshold-processed image in the memory 33. The processing circuitry 34 that realizes the threshold processing function 34b is an example of a threshold processing unit.

[0020] The processing circuitry 34 reads from the memory 33 and executes a program corresponding to the setting function 34c. The setting function 34c then sets a contrast-enhanced region in which the luminance value of contrast in the contrast-enhanced image is enhanced based on the start point and search direction set in the threshold-processed image. The start point corresponds to the point at which a search for the contrast-enhanced region begins in the threshold-processed image. The contrast-enhanced region is a region in the contrast-enhanced image in which the luminance value of contrast is enhanced. The search direction corresponds to the reference direction in the threshold-processed image for searching for the contrast-enhanced region. The target of the contrast-enhanced region is, for example, a vascular region (which may also be referred to as a peripheral vascular region) representing a subject's peripheral blood vessels or other blood vessels, or an organ region (which may also be referred to as a tissue region) representing a subject's organ (tissue / tumor, etc.). Hereinafter, the case where a peripheral vascular region is selected as the target of the contrast-enhanced region is referred to as a vascular enhancement mode. Furthermore, the case where a tissue region is selected as the target of the contrast-enhanced region is referred to as a tissue enhancement mode.

[0021] Specifically, first, the vascular region is input (selected) as the contrast-enhanced region according to the user's instruction via the input interface 31. That is, the vascular enhancement mode is selected as the target of the contrast-enhanced region. Next, according to the user's instruction via the input interface 31, the starting point and the search direction of the contrast-enhanced region are input in the threshold-processed image. The search direction is set, for example, as the direction from the starting point to the point input after the user sets the starting point. Thereby, the setting function 34c sets the starting point and the search direction in the threshold-processed image. Subsequently, the setting function 34c searches for a plurality of voxels over a predetermined time so that the vector indicating between the two voxels, i.e., the voxel serving as the search origin of the contrast-enhanced region and the voxel at the end of the search direction, converges from the starting point along the search direction in the threshold-processed image. The predetermined time corresponds to, for example, the time of pressing the mouse button on the input interface 31 (hereinafter referred to as the pressing time) after the input of the search target.

[0022] That is, the setting function 34c searches for the voxels having luminance values in the threshold-processed image from the starting point along the search direction. Specifically, the setting function 34c, based on the vector (hereinafter referred to as the immediately preceding vector) from the voxel after the immediately preceding search (hereinafter referred to as the immediately preceding voxel) to the current voxel (hereinafter referred to as the current voxel) at the current search time, identifies the search target vector among the vectors from the current voxel to the voxel at the end of the search direction (hereinafter referred to as the search target vector) that converges to the immediately preceding vector. For example, the setting function 34c identifies the search target vector with the maximum inner product with the immediately preceding vector. The operation used for identifying the search target vector is not limited to the inner product, and other known vector operations such as an operation for obtaining the amount of deviation in the directions of the two vectors (the immediately preceding vector and the search target vector) may be used.

[0023] The setting function 34c incorporates the specified search target vector and the voxels related to the vector into the contrast enhancement region. At the start of the search, the previous vector corresponds to the vector defined by the starting point and the search direction. By specifying the search target vectors over a predetermined time, the setting function 34c sets the contrast enhancement region corresponding to the blood vessel region.

[0024] Also, after setting the starting point and the search direction for the threshold-processed image, the organ region is input (selected) as the contrast enhancement region according to the user's instruction via the input interface 31. At this time, in the threshold-processed image, the setting function 34c searches for a plurality of voxels over a predetermined time so that the vector indicating between the two voxels, i.e., the voxel serving as the search origin and the voxel at the front of the search direction, diverges as it follows the search direction from the starting point. For example, when targeting blood vessels in the blood vessel enhancement mode, since actual blood vessels often run along a certain direction, these two voxels are often adjacent. Also, when searching for a tumor existing concentrated in a certain location in the organ enhancement mode, since actual tumors can take various forms such as spherical or jagged spherical, the diverging voxels (the above two voxels) may not be adjacent.

[0025] Specifically, the setting function 34c specifies, based on the previous vector, among the search target vectors, the search target vectors that diverge from the previous vector. For example, the setting function 34c specifies the search target vectors whose inner product with the previous vector is equal to or less than a predetermined value (e.g., from the minimum value to a predetermined value). The predetermined value is stored in the preset memory 33. Note that the predetermined value corresponds to the threshold for discriminating between the blood vessel region and the organ region based on the direction of the contrast agent inflow and is stored in the preset memory 33.

[0026] The operations used for specifying the search target vector are not limited to the inner product, and other known vector operations such as an operation for obtaining the amount of deviation in the directions of two vectors (the immediately preceding vector and the search target vector) may be used. By specifying the search target vector over a predetermined time period and incorporating it into the contrast enhancement region, the setting function 34c sets the contrast enhancement region corresponding to the organ region. Thereby, the setting function 34c sets the contrast enhancement region corresponding to the organ region. The setting function 34c stores the set contrast enhancement region in the memory 33. The processing circuit 34 that realizes the setting function 34c is an example of a setting unit.

[0027] The processing circuit 34 reads out and executes a program corresponding to the synthesis function 34d from the memory 33. For example, the synthesis function 34d reads out the threshold-processed image from the memory 33. Also, the synthesis function 34d reads out the contrast image, the subtraction image, and the contrast enhancement region from the memory 33. The synthesis function 34d performs alignment between the contrast image and the threshold-processed image. Note that the synthesis function 34d may perform alignment between the contrast image and the subtraction image. Since known registration-related processing is applicable to the alignment processing, the description thereof is omitted. The synthesis function 34d synthesizes the threshold-processed image with the contrast image based on the alignment between the contrast image and the threshold-processed image. For example, the synthesis function 34d aligns the threshold-processed image and the contrast image, and generates a synthesized image in which the enhancement magnification of the threshold-processed image is zero and the threshold-processed image is synthesized with the contrast image. That is, the synthesis function 34d synthesizes the contrast enhancement region in the threshold-processed image and the contrast image to generate a synthesized image.

[0028] Specifically, after generating the synthesized image, the enhancement amount of the contrast enhancement region is input according to a user's instruction via the input interface 31. The input of the enhancement amount is, for example, the number of rotations of the wheel operation on the mouse. Thereby, the synthesis function 34d enhances the luminance value of the contrast enhancement region in the threshold-processed image according to the enhancement amount according to the number of rotations in the synthesized image. As an example, the synthesis of the luminance values of two voxels at the same position (hereinafter referred to as the same position) in the contrast enhancement region in the subtraction image and the contrast image will be described.

[0029] For the sake of specificity, the following description will be given assuming that the luminance value of a voxel at a certain coordinate position in a contrast-enhanced region in a subtraction image is S (S is a natural number), and the luminance value of a voxel at the same position in a contrast-enhanced image is C (C is a natural number). The enhancement amount corresponding to the number of rotations of the wheel is n (n is a natural number). In this case, the processing circuitry 34 uses the synthesis function 34d to multiply the luminance value S of the contrast-enhanced region by the enhancement amount n (S×n) and add the luminance value C of the contrast-enhanced image to the multiplication result (S×n) (S×n+C). This allows the synthesis function 34d to enhance the luminance value of the contrast-enhanced region in the composite image according to the enhancement amount. If there were no tissue at a certain coordinate position, the luminance value of the voxel at the same position would be approximately the same in the subtraction image and the contrast-enhanced image. Therefore, the luminance value of the composite image would be (1+n) times the luminance value of the contrast-enhanced region in the contrast-enhanced image. That is, since the voxel values on the contrast image are "brightness values due to the tissue into which the contrast agent has been injected," and the voxel values on the non-contrast image are "brightness values due to the tissue," the brightness value on the subtraction image is "(brightness value due to the tissue into which the contrast agent has been injected) - (brightness value due to the tissue)." Therefore, it is ideal for the brightness values of voxels at the same position to be approximately the same in the subtraction image and the contrast image; in reality, the brightness value is the difference between the brightness values. The composition function 34d stores the generated composite image in the memory 33. The processing circuitry 34 that realizes the composition function 34d is an example of a composition unit.

[0030] The processing circuitry 34 reads out from the memory 33 and executes a program corresponding to the display control function 34e. For example, the display control function 34e causes the display 32 to display various graphical user interfaces related to input, contrast images, non-contrast images, subtraction images, threshold processed images, composite images, and the like. For example, when the composite image is volume data, the display control function 34e performs various rendering processes and / or cross-sectional transformation processes on the composite image, and causes the display 32 to display a two-dimensional image generated by an image processing function (not shown). The processing circuitry 34 that realizes the display control function 34e is an example of a display control unit.

[0031] The overall configuration of the medical image processing system 1 according to the embodiment has been described above. The process of enhancing a contrast region (hereinafter referred to as contrast enhancement process) will now be described. Fig. 2 is a flowchart showing an example of the procedure of contrast enhancement process.

[0032] (contrast enhancement treatment) (Step S201) The processing circuitry 34 uses the acquisition function 34a to acquire the contrast image and the subtraction image from the X-ray CT device 10 or the image storage device 20. The acquisition function 34a may also acquire a non-contrast image. The acquisition function 34a stores the contrast image and the subtraction image in the memory 33.

[0033] (Step S202) The input interface 31 receives a user instruction to select a blood vessel region or an organ region as a contrast-enhanced region. That is, the input interface 31 inputs a blood vessel region or an organ region as a search target prior to setting the contrast-enhanced region. For example, the input interface 31 receives a user instruction to select either a blood vessel enhancement mode in which a blood vessel region is used as a contrast-enhanced region or an organ enhancement mode in which an organ region is used as a contrast-enhanced region.

[0034] (Step S203) The processing circuit 34 executes threshold processing on the subtraction image using a threshold value by means of the threshold processing function 34b. As a result, the threshold processing function 34b generates a threshold processed image from the subtraction image. The threshold processing function 34b stores the threshold processed image in the memory 33. FIG. 3 is a diagram showing an example of the subtraction image SUB before threshold processing. Note that the threshold processing function 34b may generate a subtraction image by differentiating a non-contrast image from a contrast image, and then generate a threshold processed image from the subtraction image.

[0035] (Step S204) The processing circuit 34 performs alignment between the contrast image and the threshold processed image by means of the synthesis function 34d. Based on the alignment, the synthesis function 34d sets the enhancement magnification of the threshold processed image to zero and synthesizes the threshold processed image with the contrast image. Thereby, the synthesis function 34d generates a synthesized image. The synthesized image generated in this step has the enhancement magnification of the threshold processed image set to zero. For this reason, in the synthesized image, the threshold processed image is in a transparent state. The synthesis function 34d stores the generated synthesized image in the memory 33.

[0036] (Step S205) The processing circuit 34 causes the display 32 to display the synthesized image by means of the display control function 34e. As a result, the display 32 displays the synthesized image. At this time, since the enhancement magnification of the threshold processed image in the synthesized image is zero, in effect, the contrast image is displayed on the display 32.

[0037] (Step S206) The input interface 31 inputs a starting point for the composite image according to the user's instruction. For example, the input interface 31 inputs the position of the cursor in the composite image as the starting point (which may also be referred to as the first point) in response to the first click operation. FIG. 4 is a diagram showing an example of the starting point CL1 input (specified) for the threshold processing image TP1 in the composite image after the blood vessel enhancement mode is selected. FIG. 5 is a diagram showing an example of the starting point CL1 input (specified) for the threshold processing image TP1 in the composite image after the organ enhancement mode is selected. In FIGS. 4 and 5, the threshold processing image TP1 is shown, but in actual input, the starting point is input in the composite image with the enhancement magnification of the threshold processing image set to zero. When the starting point is input, the processing circuit 34 sets the starting point in the threshold processing image based on the alignment of the contrast image and the threshold processing image by the setting function 34c.

[0038] (Step S207) The input interface 31 inputs a search direction for the composite image according to the user's instruction. The input of the search direction is performed, for example, by clicking on a point (which may also be referred to as the second point) different from the starting point (the first point) CL1 in the composite image, clicking on a point in the composite image at a position different from the composite image at the time of input of the starting point (for example, a different slice position, etc.), or dragging at a point different from the starting point. For example, after the input of the starting point, the input interface 31 inputs the direction from the starting point to the position of the cursor in the composite image as the search direction in response to the second click operation.

[0039] FIG. 6 is a diagram showing an example of a point (second point) CL2 corresponding to a second click operation on the threshold processing image TP2 in the composite image after selecting the blood vessel enhancement mode. FIG. 7 is a diagram showing an example of a point CL2 corresponding to a second click operation on the threshold processing image TP2 in the composite image after selecting the organ enhancement mode. In FIGS. 6 and 7, threshold processing images TP2 at different slice positions with respect to the threshold processing image TP1 in the composite image for FIGS. 4 and 5 are shown. The search direction is input as the direction from the starting point (first point) CL1 specified in FIGS. 4 and 5 to the point (second point) CL2 specified in FIGS. 6 and 7. In FIGS. 6 and 7, the threshold processing image TP1 is shown, but in actual input, the second point is input in the composite image with the enhancement magnification of the threshold processing image set to zero. When the second point is input, the processing circuit 34 sets the second point on the threshold processing image based on the alignment between the contrast image and the threshold processing image by the setting function 34c. Thereby, the setting function 34c sets the direction from the first point to the second point as the search direction in the threshold processing image.

[0040] (Step S208) Based on the starting point and the search direction set on the threshold processing image by the setting function 34c, the processing circuit 34 sets a contrast enhancement region in which the luminance value of the contrast in the contrast image is enhanced in the composite image. Specifically, the setting function 34c sets the contrast enhancement region in the composite image by searching for the contrast region in response to the input for a predetermined time. Specifically, the input interface 31 starts this step with the pressing time of the mouse button triggered by the input of the second point as the predetermined time. Thereby, the compositing function 34d generates a composite image by compositing the threshold processing image, the contrast enhancement region, and the contrast image based on the alignment between the contrast image and the threshold processing image. At this time, since the amount of luminance enhancement in the contrast enhancement region is not input, the contrast enhancement region is not displayed in the composite image displayed on the display 32.

[0041] For example, when the blood vessel enhancement mode is selected and the mouse button is pressed, the setting function 34c searches for a plurality of voxels over the pressing time in a region having a luminance value in the threshold-processed image, following the search direction from the starting point, so that the vector indicating between two voxels, i.e., the voxel serving as the search origin and the voxel at the tip of the search direction, converges. Thereby, the setting function 34c sets, in the composite image, the contrast enhancement region corresponding to the blood vessel region by integrating the searched region.

[0042] Also, when the organ enhancement mode is selected and the mouse button is pressed, the setting function 34c searches for a plurality of voxels over the pressing time in a region having a luminance value in the threshold-processed image, following the search direction from the starting point, so that the vector indicating between two voxels, i.e., the voxel serving as the search origin of the contrast enhancement region and the voxel at the tip of the search direction, diverges. Thereby, the setting function 34c sets, in the composite image, the contrast enhancement region corresponding to the organ region by integrating the searched region.

[0043] FIG. 8 is a diagram showing an example of the extension of the contrast enhancement region CCAR in the blood vessel enhancement mode. As shown in FIG. 8, in the rendering image CR1, over the pressing time, the contrast enhancement region CCAR is extended via the point CL2 corresponding to the second click operation from the starting point CL1. Further, FIG. 9 is a diagram showing an example of the extension of the contrast enhancement region OCAR in the organ enhancement mode. As shown in FIG. 9, in the rendering image CR1, over the pressing time, the contrast enhancement region OCAR is extended via the point CL2 corresponding to the second click operation from the starting point CL1.

[0044] Note that in FIGS. 4 to 7, the starting point (first point) CL1 and the second click point (second point) CL2 are specified in one slice image, but it is not limited thereto. For example, on the display of a 3D image such as the rendering image shown in FIGS. 8 and 9, the starting point and the second click point may be specified.

[0045] (Step S209) The input interface 31 inputs the enhancement amount according to the user's instruction. The input of the enhancement amount is, for example, the number of rotations of the wheel operation on the mouse. Thereby, the input interface 31 inputs the enhancement amount of the luminance in the contrast enhancement region according to the number of rotations of the wheel operation on the mouse.

[0046] (Step S210) The processing circuit 34 enhances the luminance value in the contrast enhancement region of the synthesized image according to the input enhancement amount by the synthesis function 34d. That is, the synthesis function 34d changes the enhancement magnification according to the input of the enhancement amount in the synthesized image. For example, when the enhancement amount corresponding to the number of rotations of the wheel operation is 2, the synthesis function 34d enhances the luminance value of the contrast enhancement region of the contrast image three times. Specifically, the synthesis function 34d generates a synthesized image by adding the luminance values of voxels at the same position according to a predetermined enhancement amount (for example, n = i (i = the number of rotations of the wheel)).

[0047] (Step S211) The processing circuit 34 causes the display 32 to display the synthesized image with the enhancement magnification in the contrast enhancement region changed by the display control function 34e. Thereby, the display 32 displays the synthesized image. For example, in FIGS. 8 and 9, the tip of the extension of the contrast enhancement region is described as an arrow, but the arrow may not be displayed when displayed on the display 32. At this time, the display 32 may further display a non-contrast image for comparison with the synthesized image. Thus, the user can arbitrarily adjust the luminance value of the contrast enhancement region while visually recognizing the synthesized image.

[0048] (Step S212) If the pressing of the button is released in the input interface 31 (Yes in step S212), the contrast enhancement process ends. If the pressing of the button is not released in the input interface 31, that is, if the pressing of the button is maintained (No in step S212), the processes after step S208 are repeated. At this time, the extension (expansion) of the contrast enhancement region is performed.

[0049] During the processing of steps S206 to S212, the display 32 displays the composite image, which allows the user to arbitrarily adjust the luminance value of the contrast-enhanced region while visually viewing the composite image.

[0050] The medical image processing apparatus 30 according to the embodiment described above acquires a contrast image and a subtraction image, performs threshold processing on the subtraction image using a threshold related to contrast to generate a threshold-processed image, sets a start point and a search direction in the threshold-processed image, sets a contrast-enhanced region that enhances the brightness value of contrast in the contrast image based on the set start point and search direction, and generates a composite image by combining the threshold-processed image, the contrast-enhanced region, and the contrast image based on the alignment of the contrast image and the subtraction image. Furthermore, in the medical image processing apparatus 30 according to the embodiment, the contrast-enhanced region is a vascular region that indicates blood vessels or an organ region that indicates an organ in the subject.

[0051] When the contrast-enhanced region is a blood vessel region, the medical image processing apparatus 30 according to the embodiment sets the contrast-enhanced region by tracing a search direction from a starting point in the threshold-processed image and searching for a plurality of voxels over a predetermined time period so that vectors indicating the relationship between two voxels, the voxel that is the search source for the contrast-enhanced region and a voxel at the end of the search direction, converge. When the contrast-enhanced region is an organ region, the medical image processing apparatus 30 according to the embodiment sets the contrast-enhanced region by tracing a search direction from a starting point in the threshold-processed image and searching for a plurality of voxels over a predetermined time period so that vectors indicating the relationship between two voxels, the voxel that is the search source for the contrast-enhanced region and a voxel at the end of the search direction, diverge.

[0052] Accordingly, according to the medical image processing apparatus 30 according to the embodiment, the luminance values included in the contrast enhancement region in the blood vessel region or the organ region can be enhanced without enhancing the luminance values of the regions excluding the contrast enhancement region caused by the misalignment error between the contrast image and the subtraction image. That is, according to the medical image processing apparatus 30 according to the embodiment, only the luminance values in the contrast enhancement region can be enhanced without enhancing the noise caused by the misalignment error between the contrast image and the subtraction image.

[0053] In addition, the medical image processing apparatus 30 according to the embodiment inputs the position of the cursor in the threshold processing image as a starting point in response to the first click operation. After the input of the starting point, the direction from the starting point to the position of the cursor in the threshold processing image is input as a search direction in response to the second click operation. Prior to the setting of the contrast enhancement region, the blood vessel region or the organ region is input as a search target. Further, the medical image processing apparatus 30 according to the embodiment inputs the pressing time of the button as a predetermined time after the input of the search target. In addition, the medical image processing apparatus 30 according to the embodiment inputs the enhancement amount of the luminance in the contrast enhancement region according to the number of rotations of the wheel operation of the mouse, and enhances the luminance values in the contrast enhancement region of the composite image according to the enhancement amount.

[0054] Accordingly, according to the medical image processing apparatus 30 according to the embodiment, the setting of the contrast enhancement region and the adjustment of the enhancement amount can be performed by an intuitive and simple operation. Therefore, according to the medical image processing apparatus 30 according to the embodiment, the burden on the user regarding the setting of the contrast enhancement region and the adjustment of the enhancement amount can be reduced, and the throughput regarding the execution of the contrast enhancement process can be improved.

[0055] From the above, according to the medical image processing apparatus 30 according to the embodiment, by enhancing the luminance values in the contrast enhancement region desired by the user, the visibility of the contrast agent in the contrast enhancement region can be improved, and the throughput of the examination of the subject and the accuracy of reading the radiograph can be improved.

[0056] When realizing the technical idea in this embodiment with a medical image processing program, the medical image processing program causes a computer to acquire a contrast image regarding a subject, a non-contrast image regarding the subject, and a subtraction image generated from the difference between the contrast image and the non-contrast image, perform threshold processing using a threshold value regarding contrast on the subtraction image to generate a threshold-processed image, set a contrast enhancement region for enhancing the luminance value of the contrast in the contrast image based on a starting point and a search direction set in the threshold-processed image, perform alignment between the contrast image and the subtraction image, and generate a composite image by compositing the contrast enhancement region in the subtraction image and the contrast image.

[0057] For example, the contrast enhancement process can also be realized by installing a medical image processing program on a computer such as the console of the X-ray computed tomography apparatus 10 shown in FIG. 1 and / or a server (PACS server) in the image storage device 20 and deploying them in the memory. At this time, the program that can cause the computer to execute the process can also be stored in a storage medium such as a magnetic disk (such as a hard disk), an optical disk (such as a CD-ROM, DVD), or a semiconductor memory and distributed. Further, the distribution of the medical image processing program is not limited to the above media, and for example, it may be distributed using a telecommunication function such as downloading via the Internet. The processing procedure in the medical image processing program conforms to the contrast enhancement process. Also, the effects of the medical image processing program are the same as those in the embodiment. For these reasons, the description of the processing procedure and effects of the contrast enhancement process in the medical image processing program is omitted.

[0058] When realizing the technical idea in the embodiment by a medical image processing method, the medical image processing method acquires a contrast image regarding a subject, a non-contrast image regarding the subject, and a subtraction image generated by the difference between the contrast image and the non-contrast image, performs threshold processing using a threshold related to the contrast on the subtraction image to generate a threshold processed image, sets a contrast enhancement region for enhancing the luminance value of the contrast in the contrast image based on a starting point and a search direction set in the threshold processed image, performs alignment between the contrast image and the subtraction image, and synthesizes the contrast enhancement region in the subtraction image and the contrast image to generate a synthesized image. Since the processing procedure and effect of the contrast enhancement processing by the medical image processing method comply with the embodiment, the description is omitted.

[0059] According to at least the embodiments described above, the visibility of the contrast region can be improved.

[0060] Although several embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, changes, and combinations of the embodiments can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and its equivalent scope.

Explanation of Reference Numerals

[0061] 1 Medical image processing system 10 X-ray computed tomography device 20 Image storage device 30 Medical image processing device 31 Input interface 32 Display 33 Memory 34 Processing circuit 34a Acquisition function 34b Threshold processing function 34c Setting function 34d Synthesis function 34e represents a control function

Claims

1. An acquisition unit that acquires a contrast image regarding a subject, a non-contrast image regarding the subject, and a subtraction image generated from the difference between the contrast image and the non-contrast image; A threshold processing unit that executes threshold processing using a threshold value regarding contrast on the subtraction image to generate a threshold processed image; A setting unit that sets a start point and a search direction on the threshold processed image, and sets a contrast enhancement region for enhancing the luminance value of the contrast in the contrast image based on the start point and the search direction; A composition unit that composes the threshold processed image, the contrast enhancement region, and the contrast image based on the alignment of the contrast image and the threshold processed image to generate a composite image; A medical image processing apparatus comprising the above.

2. The contrast enhancement region is a blood vessel region indicating blood vessels in the subject or an organ region indicating an organ, The medical image processing apparatus according to claim 1.

3. When the contrast enhancement region is the blood vessel region, the setting unit searches a plurality of voxels over a predetermined time in the threshold processed image so that a vector indicating between two voxels, namely, a voxel serving as a search source of the contrast enhancement region and a voxel at the end of the search direction, converges along the search direction from the start point, thereby setting the contrast enhancement region. The medical image processing apparatus according to claim 2.

4. When the contrast enhancement region is the organ region, the setting unit searches a plurality of voxels over a predetermined time in the threshold processed image so that a vector indicating between two voxels, namely, a voxel serving as a search source of the contrast enhancement region and a voxel at the end of the search direction, diverges along the search direction from the start point, thereby setting the contrast enhancement region. The medical image processing apparatus according to claim 2.

5. The position of the cursor in the threshold processed image is input as the start point in response to a first click operation, After the input of the start point, the direction from the start point to the position of the cursor in the threshold processed image is input as the search direction in response to a second click operation, The medical image processing apparatus according to claim 3 or 4, further comprising an input unit that inputs the blood vessel region or the organ region as a search target prior to the setting of the contrast enhancement region. The medical image processing apparatus according to claim 3 or 4.

6. After the input of the search target, the input unit inputs the time of pressing a button as the predetermined time. The medical image processing apparatus according to claim 5.

7. The input unit inputs the amount of enhancement of the luminance in the contrast enhancement region according to the number of rotations of the wheel operation on the mouse. The synthesizing unit enhances the luminance value in the contrast enhancement region of the synthesized image according to the amount of enhancement. The medical image processing apparatus according to claim 5.

8. Causes a computer to acquire a contrast image regarding a subject, a non-contrast image regarding the subject, and a subtraction image generated from the difference between the contrast image and the non-contrast image regarding the subject; perform threshold processing using a threshold regarding contrast on the subtraction image to generate a threshold-processed image; set a starting point and a search direction on the threshold-processed image, and set a contrast enhancement region for enhancing the luminance value of the contrast in the contrast image based on the starting point and the search direction; generate a synthesized image by synthesizing the threshold-processed image, the contrast enhancement region, and the contrast image based on the alignment between the contrast image and the threshold-processed image. A medical image processing program for realizing the above.

9. acquire a contrast image regarding a subject, a non-contrast image regarding the subject, and a subtraction image generated from the difference between the contrast image and the non-contrast image regarding the subject; perform threshold processing using a threshold regarding contrast on the subtraction image to generate a threshold-processed image; set a starting point and a search direction on the threshold-processed image, and set a contrast enhancement region for enhancing the luminance value of the contrast in the contrast image based on the starting point and the search direction; generate a synthesized image by synthesizing the threshold-processed image, the contrast enhancement region, and the contrast image based on the alignment between the contrast image and the threshold-processed image. A medical image processing method comprising the above.

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