JP5908241B2 - Medical image display device - Google Patents

Description

  Embodiments described herein relate generally to a medical image display apparatus.

  The medical image display device is a device that displays a medical image of a subject imaged by a medical image photographing device such as an X-ray CT device (X-ray computer tomography device) or an MRI device (magnetic resonance imaging device). A medical image displayed by the medical image display device is observed by a doctor, a clinical laboratory technician, or the like, and diagnosis and treatment are performed. In particular, medical images such as blood vessels are displayed three-dimensionally to facilitate diagnosis and treatment.

  Here, as a representative method for displaying a medical image three-dimensionally, there are a VR method (volume rendering method), a MIP method (maximum value projection method), and the like. With these methods, three-dimensional volume data (for example, voxel data) is processed, and a medical image is generated. Volume data is three-dimensionally constructed by superimposing slice images (cross-sectional images) taken by an X-ray CT apparatus, an MRI apparatus, or the like.

  In the above-described VR method, a virtual light source is set, a single ray (ray) is applied to the object from the line-of-sight direction, light is absorbed and reflected discretely for each voxel, and an image is displayed on the two-dimensional projection plane. Can be displayed and various images can be displayed by setting opacity (opacity) and the like. In particular, in the SVR method (volume rendering method with shadow), a medical image (SVR image) is generated in which a target is shaded and the target is stereoscopically displayed.

  The MIP method is a method for performing projection processing on volume data in an arbitrary viewpoint direction and displaying the maximum value in the projection path on the projection plane. Usually, for all original images to be processed, The maximum value is extracted for each pixel on each projection path, that is, the projection line, and a medical image (MIP image) is generated.

JP 2003-91735 A

  However, the display method based on the MIP method described above is effective for diagnosis because the pixel value such as the CT value is retained and shown as it is. However, since the MIP image has no sense of depth, the anteroposterior relationship between blood vessels is effective. Is difficult to grasp, and it is necessary to perform diagnosis using a plurality of MIP images with different angles. On the other hand, in the display method based on the SVR method, although the anteroposterior relationship of blood vessels and the like is easy to understand, the information on the pixel values disappears, so it is necessary to perform diagnosis using another image corresponding to the information.

  The problem to be solved by the present invention is to provide a medical image display device capable of displaying the front-rear relationship between blood vessels in an easy-to-understand manner while ensuring information on pixel values.

The medical image display apparatus according to the embodiment includes an image generation unit that generates at least one of a maximum value projection image, a minimum value projection image, and an addition average projection image from volume data, and a blood vessel surface in the volume data. An image in which a plurality of pixel values of the projection image generated by the image generation unit are changed so that the blood vessels of the projection image generated by the image generation unit are shaded using information on the difference between the normal line and the reference direction. A processing unit and an image display unit that displays the projection image changed by the image processing unit.

It is a block diagram which shows schematic structure of the medical image display apparatus which concerns on embodiment. It is a flowchart which shows the flow of the image display process which the medical image display apparatus shown in FIG. 1 performs. It is a figure which shows an example of a MIP image. It is a figure which shows an example of the SVR image corresponding to the MIP image shown in FIG. It is a figure which shows the processed MIP image which processed the MIP image shown in FIG. It is a figure which shows the processed MIP image shown in FIG. 5 after coloring.

  An embodiment will be described with reference to the drawings.

  As shown in FIG. 1, a medical image display apparatus 1 according to the present embodiment includes a volume data storage unit 2 that stores volume data, a MIP image generation unit 3 that generates an MIP image (maximum value projection image), and an SVR. An SVR image generation unit 4 that generates an image (volume rendering image with shadow), an input unit 5 that is input by an operator, an MIP image storage unit 6 that stores an MIP image, and an SVR image storage that stores an SVR image Unit 7, an image processing unit 8 that processes the MIP image, and an image display unit 9 that displays various images such as the MIP image, the SVR image, and the processed MIP image.

  The volume data storage unit 2 stores volume data transmitted from an external device such as a medical image photographing device. The volume data is configured by superimposing slice images (cross-sectional images) captured by a medical image capturing apparatus such as an X-ray CT apparatus or an MRI apparatus.

  The MIP image generation unit 3 reads volume data from the volume data storage unit 2, performs projection processing using the MIP method (maximum value projection method) on the read volume data, and generates an MIP image. The MIP image generation unit 3 functions as a first image generation unit that generates an MIP image from volume data.

  The SVR image generation unit 4 reads the volume data from the volume data storage unit 2, performs a projection process using the SVR method (shadowed volume rendering method) on the read volume data, and corresponds to the aforementioned MIP image. An SVR image is generated. The SVR image corresponding to the MIP image is an SVR image having the same angle, magnification, and movement amount as the MIP image generated above. The SVR image generation unit 4 functions as a second image generation unit that generates an SVR image corresponding to the aforementioned MIP image from the volume data.

  Here, in the shadow rendering of volume rendering, the pixel value of the image is changed based on the inclination information (for example, the normal direction of the surface of the object) of the surface of the object (for example, a blood vessel or an organ) in the volume data. . For example, the pixel value is changed based on the difference between the normal direction of the object surface and the reference direction (light source direction). As an example of this change, the pixel value is changed so that a portion where the reference direction and the normal direction are the same is bright and a portion where the difference is large is dark. In this way, the object is shaded.

  In the present embodiment, reflection information (for example, the reflection coefficient of each pixel (voxel)) of the object surface is used as an example of information regarding the difference between the normal direction of the object surface and the reference direction. At this time, the SVR image generation unit 4 also functions as a reflection information generation unit that generates reflection information.

  The input unit 5 is an operation unit that is input by an operator, and includes an input device such as a keyboard and a mouse. The input unit 5 is used by an operator to perform various input operations such as an image generation instruction, an image display instruction, and an image switching instruction.

  The MIP image storage unit 6 stores the MIP image generated by the MIP image generation unit 3. For example, a magnetic disk device or a semiconductor disk device (flash memory) can be used as the MIP image storage unit 6.

  The SVR image storage unit 7 stores the SVR image generated by the SVR image generation unit 4 together with the reflection information described above. As the SVR image storage unit 7, for example, a magnetic disk device, a semiconductor disk device (flash memory), or the like can be used in the same manner as the MIP image storage unit 6 described above.

  The image processing unit 8 includes a reflection information acquisition unit 8a that acquires reflection information from the SVR image storage unit 7, a reflection information storage unit 8b that stores the acquired reflection information, and shades the MIP image using the reflection information. Processing information calculation unit 8c for calculating processing information for processing, processing information storage unit 8d for storing the calculated processing information, MIP image processing unit 8e for processing a MIP image using the processing information, and processed MIP And a processed MIP image storage unit 8f for storing images.

  The reflection information acquisition unit 8a reads the reflection coefficient (reflectance) of each pixel (voxel) when generating the SVR image from the SVR image storage unit 7, and obtains reflection information indicating the reflection coefficient for each pixel of the SVR image.

  The reflection information storage unit 8b stores the reflection information calculated by the reflection information calculation unit 8a. For example, a magnetic disk device or a semiconductor disk device (flash memory) can be used as the reflection information storage unit 8b.

  The processing information calculation unit 8c reads the reflection information from the reflection information storage unit 8b, calculates the processing amount of the pixel value for each pixel from the reflection coefficient of each pixel using the read reflection information, and the processing amount for each pixel Processing information indicating (for example, the amount by which the CT value is lowered) is obtained.

  The machining information storage unit 8d stores the machining information calculated by the machining information calculation unit 8c. As the processing information storage unit 8d, for example, a magnetic disk device, a semiconductor disk device (flash memory), or the like can be used in the same manner as the reflection information storage unit 8b.

  The MIP image processing unit 8e reads the processing information from the processing information storage unit 8d, reflects the processing amount for each pixel on the MIP image using the processing information thus read, and shades the MIP image.

  The processed MIP image storage unit 8f stores the MIP image processed by the MIP image processing unit 8e. As the processed MIP image storage unit 8f, for example, a magnetic disk device, a semiconductor disk device (flash memory), or the like can be used similarly to the reflection information storage unit 8b and the processed information storage unit 8d described above.

  Here, such an image processing unit 8 may be configured by hardware such as an electric circuit, or may be configured by software such as a program for executing these functions. It may be configured by a combination of both. Further, as described above, various storage units are provided. However, the present invention is not limited to this, and for example, a common storage unit having a capacity necessary for data storage may be provided.

  The image display unit 9 displays various images such as the MIP image stored in the MIP image storage unit 6, the SVR image stored in the SVR image storage unit 7, and the processed MIP image stored in the processed MIP image storage unit 8f. indicate. For example, a liquid crystal display or a CRT (Cathode Ray Tube) display can be used as the image display unit 9.

  Next, image display processing performed by the medical image display apparatus 1 described above will be described in detail. When an operator such as a doctor or a clinical laboratory technician performs an input operation on the input unit 5 to instruct generation of an MIP image and an SVR image, the following processing is executed.

  As shown in FIG. 2, first, an MIP image G1 is generated by the aforementioned MIP image generation unit 3 (step S1). Next, an SVR image G2 corresponding to the generated MIP image G1 is formed by the SVR image generation unit 4 (step S2).

  In the generation of the MIP image G1 in step S1, the volume data stored in the volume data storage unit 2 is used to generate the MIP image G1. For example, the maximum value is extracted for all pixels on the projection path, that is, the projection line, for all original images to be processed, and the MIP image G1 is generated.

  As shown in FIG. 3, the MIP image G1 is an image that has insufficient depth and it is difficult to grasp the front-rear relationship between blood vessels. However, the MIP image G1 is an effective image for diagnosis because the pixel value such as the CT value is retained and shown as it is. In particular, the MIP image G1 is effective for diagnosis of thin blood vessels and calcification in the blood vessels.

  In the generation of the SVR image G2 in step S2, the volume data stored in the volume data storage unit 2 is used similarly to the generation of the MIP image G1, and the same angle, enlargement ratio, and movement as the MIP image generated in the above-described step S1. An SVR image G2 having a quantity is generated. For example, a virtual light source is set, a single ray (ray) is applied to the target from the line-of-sight direction, light is absorbed and reflected for each voxel, and an image is generated on the two-dimensional projection plane. Is done. Further, at this time, an SVR image G2 is generated in which the object is shaded and the object is stereoscopically displayed. It should be noted that when the SVR image G2 is generated, reflection information used for the generation is obtained by calculation of the SVR image generation unit 4.

  As shown in FIG. 4, the SVR image G2 has a sense of depth compared to the MIP image G1 (see FIG. 3), and is an image that makes it easy to grasp the anteroposterior relationship between blood vessels. However, the SVR image G2 is a disadvantageous image for diagnosis because it does not hold pixel values such as CT values and information on the pixel values disappears.

  Such MIP image G1 and SVR image G2 are images having the same angle, enlargement ratio, and movement amount, and are stored in association with each other. The MIP image G1 is stored by the MIP image storage unit 6, and the SVR image G2 is stored by the SVR image storage unit 7 together with the reflection information.

  Returning to FIG. 2, after completion of step S2, the reflection information at the time of generating the SVR image G2 is obtained by the reflection information acquisition unit 8a (step S3), and the processing information is obtained from the reflection information by the processing information calculation unit 8c. (Step S4).

  In the calculation of the reflection information in step S3, the reflection coefficient (reflectance) of each pixel (voxel) at the time of generating the SVR image is read from the SVR image storage unit 7, and reflection information indicating the reflection coefficient for each pixel of the SVR image is obtained. It is done. This reflection information is stored by the reflection information storage unit 8b.

  In the calculation of the processing information in step S4, the reflection information is read from the reflection information storage unit 8b, and the read reflection information is used to calculate the pixel value processing amount for each pixel from the reflection coefficient of each pixel. Is done. Thereby, the processing information which shows the processing amount for every pixel (for example, the amount which makes CT value low) is calculated | required. This processing information is stored by the processing information storage unit 8d.

  After completion of step S4, the above-described processing information is used to process the MIP image G1 by the MIP image processing unit 8e (step S5), and the processed processed MIP image G3 is displayed by the image display unit 9 ( Step S6).

  In the processing of the MIP image G1 in step S5, the processing information is read out from the processing information storage unit 8d, the processing information thus read is used, the processing amount for each pixel is reflected in the MIP image G1, and the MIP image G1 is shaded. Thereby, the processed MIP image G3 is generated, and this processed MIP image G3 is displayed by the image display unit 9 in the next step S6.

  As shown in FIG. 5, the processed MIP image G3 has a sense of depth compared to the MIP image G1 (see FIG. 3), and as with the SVR image G2, it is easy to grasp the anteroposterior relationship between blood vessels. It is. This is because a portion with a low reflection coefficient becomes darker than a portion with a high reflection coefficient by shading, and a line is displayed at the intersection of blood vessels. Further, the processed MIP image G3 is an image that is effective for diagnosis because the pixel value such as the CT value is held as it is, as is the case with the original MIP image G1.

  Therefore, the processed MIP image G3 is a MIP image having a sense of depth, and is displayed with shadows on the edge portions such as blood vessels, so that the front-rear relationship between intersecting blood vessels can be easily grasped. It becomes possible. In addition, compared with the MIP image G1 (see FIG. 3), the processed MIP image G3 can grasp the position of the blood vessel that has become invisible due to the bone.

  As described above, in the image display process, the pixel value of the MIP image G1 is slightly changed by using the reflection coefficient obtained for shadowing when the SVR image G2 is generated, while ensuring the pixel value information. The context of blood vessels can be displayed in an easy-to-understand manner.

  As a simple flow of calculation, an SVR image G2 having the same angle as the angle to be displayed is generated by the MIP method. The reflection coefficient calculated simultaneously when the SVR image G2 is generated is held for each pixel on the screen. Subsequently, the pixel value of each pixel of the MIP image G1 is processed based on the calculated reflection coefficient of each pixel (the pixel value is subtracted based on the reflection coefficient). As a result, the portion with a low reflection coefficient becomes blacker than the portion with a high reflection coefficient, and a line is displayed at the intersection of blood vessels. For this reason, it becomes possible to easily determine the front-rear relationship between blood vessels.

  As described above, according to the present embodiment, the reflection information for shadowing when the SVR image G2 is generated is used, and the MIP image G1 generated by the MIP image generation unit 3 is subjected to shadowing processing. Is called. As a result, the shaded processing is performed on the MIP image G1, the processed MIP image G3 has a sense of depth, and, like the SVR image G2, it is an image that can easily grasp the anteroposterior relationship between blood vessels. Further, the processed MIP image G3 is an image that is effective for diagnosis because the pixel value such as the CT value is held as it is, as is the case with the original MIP image G1. Thereby, it is possible to display the front-rear relationship between the blood vessels in an easy-to-understand manner while securing information on the pixel values.

  Further, when a plurality of shaded blood vessels and the like are mixed and mixed, by selecting a target object (for example, one blood vessel) which is a region to be focused on from the SVR image G2 (or MIP image G1). Alternatively, only the target object may be shaded and displayed. Thereby, observation becomes easier.

  In this case, the operator performs an input operation on the input unit 5 such as a mouse, moves the pointer on the target object on the SVR image G2 (or MIP image G1) displayed by the image display unit 9, and clicks. , Specify the object of interest. In response to this input operation, the image processing unit 8 obtains a connected region of the target object, extracts a target object that is a part of interest in the SVR image G2 (or MIP image G1), and extracts only the extracted target object. The shadowing process is performed. Note that the image processing unit 8 can also process the obtained connection region by an existing processing method as necessary.

  Further, in order to enable easier observation, coloring indicating the front-rear relationship between the object of interest and another object may be performed. In this case, when the target object is extracted as described above, it is possible to more easily grasp the context of the blood vessel or the like by coloring the target object in consideration of the distance in the Z direction. become.

  Here, as shown in FIG. 6, if the object of interest is a single blood vessel, blue B (dot portion in FIG. 6) is displayed when the other object is behind the blood vessel, and the object is in front. Is colored red (the stripe portion in FIG. 6).

  In this coloring process, first, when generating the MIP image G1, the Z coordinate of each pixel is also calculated. Thereafter, the Z coordinate of the MIP image G1 is compared with the Z coordinate of the target object for the pixel on the target object. When the Z coordinate of the MIP image is within a predetermined threshold with the Z coordinate of the object of interest, the display color is not changed. If the Z coordinate of the MIP image is behind the Z coordinate of the object of interest and a predetermined threshold, that portion is expressed in blue B. On the other hand, when the Z coordinate of the MIP image is present in front of the Z coordinate of the object of interest and exceeds a predetermined threshold value, that portion is expressed in red R.

  In the above-described embodiment, the MIP image generation unit 3 that generates an MIP image is described as the first image generation unit. However, the present invention is not limited to this. For example, the minimum value projection method ( An image generation unit that generates a minimum value projection image by MinIP) may be used, or an image generation unit that generates an addition average projection image by an addition average projection method may be used. Even in this case, the same effect as described above can be obtained.

  As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 Medical image display apparatus 3 MIP image generation part 4 SVR image generation part 8 Image processing part 8a Reflection information calculation part 8c Processing information calculation part 8e MIP image processing part 9 Image display part G1 MIP image (maximum value projection image)
G2 SVR image (shaded volume rendering image)
G3 processed MIP image

Claims (4)

An image generation unit that generates at least one of a maximum value projection image, a minimum value projection image, and an addition average projection image from volume data;
The information generated by the image generation unit is used to shade the blood vessel of the projection image generated by the image generation unit using information on a difference between the normal of the blood vessel surface in the volume data and a reference direction . An image processing unit for changing a plurality of pixel values of the projection image;
An image display unit for displaying the projection image changed by the image processing unit;
A medical image display device comprising: Before Symbol image processing unit,
As information on the difference between the normal of the blood vessel surface and the reference direction, a reflection information acquisition unit that acquires reflection information indicating a reflection coefficient for each pixel;
A processing information calculation unit that calculates processing information indicating a processing amount of the pixel value for each pixel using the reflection information acquired by the reflection information acquisition unit;
An image processing unit that changes the pixel value for each pixel using the processing information calculated by the processing information calculation unit;
The medical image display apparatus according to claim 1 , further comprising: The medical image display apparatus according to claim 1, wherein the image processing unit extracts an object to be noticed from the projection image, and changes the pixel value only for the extracted object . 4. The image processing unit according to claim 1, wherein the image processing unit extracts an object of interest from the projection image, and performs coloring that indicates a spatial relationship between the extracted object and another object. 5. A medical image display device according to claim 1.