JP2007175271A - Medical image processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To display an image of lumen structure such as the stomach and the intestines without any overlapping of front/rear walls in the projection display. <P>SOLUTION: This image processor is provided with a storage section 1 storing three-dimensional image data related to a portion including the lumen, an extraction section 2 extracting the lumen region including the lumen from the three-dimensional image data, and a projection image creation section 3 creating a plurality of partial projection images on a plurality of partial areas constituting the extracted lumen region from the three-dimensional image data. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a medical image processing apparatus that processes an image of a luminal structure such as a stomach or intestine.

  In gastric double contrast examination using an X-ray diagnostic apparatus, a contrast agent such as barium and a foaming agent are taken and an X-ray image is taken. This method makes it possible to observe fine irregularities in the stomach wall. However, since the contrast agent adheres to both the X-ray tube side (front side) and the detector side (rear side) of the stomach wall, whether the unevenness is present on the front side or the rear side of the stomach wall from the obtained image. It is difficult to judge.

  Patent Document 1 describes an example in which a surface of a blood vessel viewed from the inside is displayed in a developed view in which the surface is shaded. As the image data, a three-dimensional image taken by CT or the like is assumed, and an image generation method is described as one of a surface method, a volume rendering method, and a depth method.

  However, in the method of Patent Document 1, it is necessary to trace the center line of the luminal structure, and it takes time and effort to display. The surface method, volume rendering method, and depth method generate appropriate images. For this reason, it is necessary to select image generation conditions, and there is a problem that it takes time and effort to operate.

  Patent Document 2 describes that a developed view of the large intestine is displayed. Although a detailed method for generating an image is not described, it can be considered that a method similar to that in Document 1 above is assumed and has the same problem.

As a method for displaying coronary arteries, in Patent Document 3, in order to create a MIP image of a coronary artery from a contrasted CT image, a heart chamber (which is also contrasted) which is a large structure near the coronary artery is removed, A method for generating a coronary image is described.
Japanese Patent Laid-Open No. 11-318884 US Patent No. 5,891,030 JP 11-242739 A

  An object of the present invention is to display an image of a luminal structure such as the stomach or intestine without overlapping front and rear walls in projection display.

In the first aspect of the present invention, the medical image processing apparatus stores a three-dimensional image data related to a part including a lumen, and an extraction process for extracting a lumen region including the lumen from the three-dimensional image data. And a projection image generation unit that generates a plurality of partial projection images related to a plurality of partial regions constituting the extracted lumen region from the three-dimensional image data.
In the second aspect of the present invention, the medical image processing apparatus extracts a storage unit that stores three-dimensional image data relating to a part including a lumen, and extracts a wall region of the lumen from the three-dimensional image data by threshold processing. A projection processing unit that performs projection processing on the three-dimensional image data from a plurality of directions, with a projection stop condition that a projection search point first exits the wall region that has undergone expansion processing; a processing unit; an expansion processing unit that performs expansion processing on the wall region; And a projection image generation unit that generates a plurality of partial projection images.
In the third aspect of the present invention, the medical image processing apparatus stores a three-dimensional image data relating to a part including a lumen, and extracts a wall region of the lumen by threshold processing from the three-dimensional image data. Projecting the three-dimensional image data from a plurality of directions using a processing unit, an expansion processing unit for expanding the wall region, and a projection stop point that the projection search point reaches the inner edge depth of the wall region subjected to the expansion processing A projection image generation unit that performs processing to generate a plurality of partial projection images.
In the fourth aspect of the present invention, the medical image processing apparatus performs a storage unit that stores three-dimensional image data related to a part including a lumen, and a radial direction from a substantially central axis of the lumen region including the lumen. The developed image is generated from the three-dimensional image data in which the developed image is distributed from the three-dimensional image data in which the projection processing value is distributed with the angle in the circumferential direction around the approximate central axis as the vertical axis and the position on the approximate central axis as the horizontal axis. The developed image generation unit includes an extraction processing unit that extracts a wall region of the lumen from the three-dimensional image data by threshold processing, an expansion processing unit that performs expansion processing on the wall region, and the expansion The projection process is characterized in that the projection stop point is that the projection search point first exits the processed wall area.
In the fifth aspect of the present invention, the medical image processing apparatus performs a storage unit that stores three-dimensional image data regarding a part including a lumen, and a radial direction from a substantially central axis of the lumen region including the lumen. The developed image is generated from the three-dimensional image data in which the developed image is distributed from the three-dimensional image data in which the projection processing value is distributed with the angle in the circumferential direction around the approximate central axis as the vertical axis and the position on the approximate central axis as the horizontal axis. The developed image generation unit includes an extraction processing unit that extracts a wall region of the lumen from the three-dimensional image data by threshold processing, an expansion processing unit that performs expansion processing on the wall region, and the expansion The projection processing is characterized in that the projection search point is that the projection search point reaches the inner edge depth of the processed wall region.

  According to the present invention, it is possible to display an image of a luminal structure such as the stomach or intestine without overlapping front and rear walls in projection display.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows the configuration of a medical image processing apparatus according to this embodiment. The three-dimensional image storage unit 1 stores three-dimensional image data relating to a part including a lumen such as the stomach or intestine. The three-dimensional image data is generated using an image generating apparatus such as an X-ray computed tomography apparatus (CT), a magnetic resonance imaging apparatus (MRI), or a digital X-ray tomography apparatus. FIG. 2 shows an example of a schematic configuration of a digital X-ray tomography apparatus. The digital X-ray tomography apparatus of FIG. 2 includes an X-ray tube device 50 and an X-ray detector device 60 that is disposed opposite to the X-ray tube device 50 with the subject P interposed therebetween. The X-ray tube device 50 is portable due to a stand 51 with casters 52 attached thereto. The stand 51 is mounted with a housing 54 that houses the X-ray tube 53. The X-ray tube 53 is supported by an X-ray tube rotation mechanism (not shown) so as to be rotatable about the imaging center axis SC with the X-ray center axis XC inclined with respect to the imaging center axis SC. The X-ray detector device 60 is portable by a stand 61 with a caster 62. The stand 61 is mounted with a housing 64 that houses the X-ray detector 63. As the X-ray detector 63, a flat panel detector having a plurality of solid-state detection elements arranged in a two-dimensional shape is employed. The X-ray detector 63 is supported by a detector rotation mechanism (not shown) so as to be rotatable about the imaging center axis SC. X-ray imaging is repeated while the X-ray tube 53 and the X-ray detector 63 rotate. Thereby, a tomographic image is reconstructed in multi slices from digital X-ray images taken from a plurality of directions. In this case, a set of a plurality of tomographic images constituting a multi-slice is referred to as three-dimensional image data (volume data). In addition, when a stomach part image is image | photographed with a digital X-ray tomography apparatus, a gastric double contrast method is used.

  The region extraction unit 2 is a processing unit that extracts a lumen region including a lumen, specifically a region including a lumen wall with a sufficient margin, from the three-dimensional image data. It has a filter processing unit 21, a threshold value determination processing unit 22, a threshold value processing unit 23, a form calculation processing unit 24, and a connected region selection processing unit 25. The projection image generation unit 3 is a processing unit that generates a plurality of partial projection images related to a plurality of partial regions constituting the lumen region extracted by the region extraction unit 2 from three-dimensional image data. Depending on the type of image to be performed, the front and rear wall surface divided projection image generation processing unit 31, the plane surface division projection image generation processing unit 32, the curved surface division projection image generation processing unit 33, the wall surface automatic division projection image generation processing unit 34, and the unfolded projection image generation A processing unit 35 is included.

  FIG. 3 shows an outline of an image processing procedure according to this embodiment. For convenience of explanation, it is assumed that the target is a stomach and three-dimensional image data obtained by double contrast of the stomach is handled. Three-dimensional image data acquired by the digital X-ray tomography apparatus is stored in the three-dimensional image storage unit 1 of the medical image processing apparatus according to this embodiment. Next, in the image processing step by the region extraction unit 2, image processing as preprocessing for the subsequent projection processing step is performed on the stored three-dimensional image. In this image processing, a region including the lumen wall is extracted. In the projection image generation step by the projection image generation unit 3, a projection process such as a maximum value projection method (MIP) or an average value projection method is performed using the extracted region including the lumen wall, and a plurality of partial projection images And a developed image is generated. As described later, a plurality of partial projection images and developed images are images together with division method options for partial areas, projection method options for generation of partial projection images, projection line-of-sight direction setting fields, and image processing parameter adjustment item setting fields. The display processing unit 4 configures a single screen and displays it on the image display unit 5 (see FIG. 15).

  FIG. 4 shows a detailed procedure of the image processing step of FIG. First, in the filter processing step by the filter processing unit 21, preprocessing such as high-frequency emphasis is performed on the three-dimensional image data. In cases other than double-contrast images, the detailed concavo-convex structure is emphasized by this processing, and the stomach wall can be easily extracted in subsequent steps. Hereinafter, this image is referred to as a three-dimensional lumen image.

  Next, in the previous stage of the threshold determination processing step by the threshold determination processing unit 22, the projection image is displayed as a projection image generated by projection processing such as maximum value projection (MIP) from the filtered three-dimensional image data. The operator operates an operation unit (not shown) and appropriately adjusts the display conditions (gray level GL, window width WW) so that the contrast of the displayed image is appropriate. From the adjusted gray level GL and the window width WW, a threshold value for extracting a lumen region including the lumen, for example, a region including the stomach wall is determined.

  The next step uses the hysteresis threshold to determine the four thresholds needed to extract the high and low luminance values of the image. For example, when the pixel value displayed in black on the display image is “0” and the pixel value displayed in white is “1.0” based on the values of the gray level GL and the window width WW, the four threshold values are For example, Tnu = 0.05, Tnl = 0.15, Tpl = 0.25, and Tpu = 0.35. Naturally, these values are calculated as different values depending on the settings of the gray level GL and the window width WW. That is, four threshold values are set by an operation of setting the display condition of the projection image by the gray level GL and the window width WW. Therefore, no additional operation for setting the threshold value occurs.

  When the threshold is determined, a threshold processing step by the threshold processing unit 23 is executed. In this step, the three-dimensional image data is binarized by threshold processing. As a result of this processing, in the case of a digital tomosynthesis image of double stomach contrast, a region (contrast region) to which a contrast agent is attached is extracted. For the threshold processing, normal simple threshold processing with the threshold Tpl is applied, or hysteresis threshold processing using the thresholds Tpu and Tpl is applied. The hysteresis threshold is a process of extracting a region including one or more pixels having a pixel value larger than Tpu from a connected region of pixels having a pixel value larger than the threshold value Tpl (see FIGS. 5A and 5B). .

  By expanding this hysteresis threshold, among the connected region of pixels having a pixel value larger than the threshold value Tpl, a region including one or more pixels having a pixel value larger than Tpu and a connected region of pixels having a pixel value smaller than the threshold value Tnl Among them, it is possible to apply a process of extracting both regions including one or more pixels having pixel values smaller than Tnu. This method has an effect that not only the region to which the contrast agent is adhered but also a part of the gap can be extracted, and the stomach wall can be extracted more reliably.

  It is also possible to detect the stomach wall surface by utilizing the fact that the pixel value inside the stomach is lower than the outside. The contrast region is a point on the stomach wall, and it is a premise that the stomach wall can be extracted in the subsequent processing by being densely arranged to some extent. However, this premise may not be fully satisfied depending on how the contrast agent is attached. Here, using the fact that the pixel value inside the stomach is low compared to the outside, the point on the stomach wall surface is added, and by adding this processing, even if the points on the stomach wall are not sufficiently dense, The stomach wall can be extracted correctly.

(1) Threshold processing is performed on a three-dimensional image S (r) that has not been subjected to high-frequency emphasis using several types of threshold values Ti. The binarized image bi (r) is a region (S (r) <Ti region) composed of pixels having pixel values less than the threshold value Ti.

(2) Select a threshold value. A threshold value Ti at which the overlapping region of the contrast region obtained by the above processing and the region (1) overlaps most widely is selected. At this time, the boundary of S (r) <Ti roughly represents the stomach wall surface.

(3) Smooth the boundary. The region of S (r) <Ti is smoothed using a morphological operation (dilation after erosion). You may add the process which removes except a connection area | region with the largest volume.

(4) Add a stomach wall point to the region. Of the points on the boundary of the region obtained in (3), select points that are at a certain distance d1 or more away from the contrast region and that are larger than a certain distance d2 and then select those points above Add to the area. The distance d1 may be 0, and is preferably not more than twice the number of pixels to be dilated for the later-described morphological operation processing.

  Next, a morphological calculation processing step by the morphological calculation processing unit 24 is performed. As a result of the previous processing, a contrast agent adhesion region (S) scattered on the stomach wall was extracted. Dilation processing (expansion processing) is performed on the region S (see FIG. 5C). A fixed value such as the number of pixels corresponding to 15 mm is sufficient as the number of pixels to dilate, but it may be configured so that the operator can change the value based on the quality of the result. By the dilation processing, a region that sufficiently includes the stomach wall region and has no connectivity with respect to the direction intersecting the line-of-sight direction of the projection processing is generated. This area without a gap can realize that the projection processing described later is satisfactorily stopped at the trailing edge of the area.

  As another method, a method for performing distance conversion can also be selected. The distance conversion is a process of calculating the distance to the region S for pixels other than the region S (distance converted image). In the area S, the value of the distance conversion image is 0. If a distance conversion image is obtained, an extended distance (for example, 15 mm) can be given to obtain a 15 mm extended area of the area S in a very short processing time. Therefore, redrawing after changing the extended distance can be performed at high speed, and the operator can easily perform an operation of looking at the displayed separated projection image and correcting it to an appropriate extended distance.

  Note that morphological operation is a general term for dilation, erosion, and logical operations using them, and there are processing that uses a binary image and processing that uses a gradation image.

  It is advantageous in terms of processing efficiency that the number of pixels to be subjected to dilation processing is as small as possible. The purpose of dilation is to connect pixels lined up in the vicinity of the stomach wall so that the stomach wall surface is formed of a lump area without a hole. The number of pixels to be dilated may be a minimum value in which the topology is the same as that of the stomach wall. By using this method, it is possible to avoid a hole remaining in the stomach wall even after dilation. Since the topology of the three-dimensional figure can be expressed by “number of holes” and “number of cavities”, calculate the “number of holes” and “number of cavities” in the connected area after dilation, and this will be the same as the stomach wall Dilation is required for the number of pixels.

  Since the stomach wall surface is open at the boundary of the three-dimensional image, in that case, it is topologically donut-shaped, with the number of holes = 1 and the number of cavities = 0. If one of the openings is closed, the number of holes = 0, the number of cavities = 0, and if both openings are closed, the number of holes = 0 and the number of cavities = 1, The number of pixels may be a minimum value such that the number of holes ≦ 1 and the number of cavities ≦ 1.

  The method of calculating the “number of holes” and “number of cavities” in the connected region is known, and by classifying the arrangement pattern of one pixel for every adjacent 2 × 2 × 2 = 8 pixels, and counting them up It is known to be required.

  Next, a connection area selection process, the expanded area obtained in the dilation process includes structures other than the stomach wall. However, since the area including the stomach wall and the other areas are always separated, only the connected area (area e) including the stomach wall can be selected by the connected component labeling process or the connected area extraction process. . For each connected region separated by the connected component labeling process, the number of pixels is calculated, and one region having the most suitable range of pixels as the stomach wall region is selected. As an alternative to this treatment, a seeded region growing method can be used.

  The selection of the connected area is an option, and if this is not used, the extended image in the area S may be used as the area e as it is.

  If a region other than the stomach is erroneously extracted, the erroneous extraction can be removed by performing the connected region, so that the region including the stomach wall can be more reliably extracted by performing the connection region selection process. effective.

As another method of image processing step (gastric wall extraction), as gray level dilation processing,
1. Filtering
2. Gray level dilation processing
Can also be used. In this case, in the abort process (stop process) when generating the projection image illustrated in FIG. 5D, the abort process using the threshold values Tpu and Tpl is performed.

  The projection image generation process in FIG. 3 will be described. As a processing procedure based on the basic concept, from a three-dimensional image, a projection image (partial projection image) on the near wall surface and a projection image (partial projection image) on the back wall surface as viewed from the line-of-sight direction of the projection processing are separated. Is generated.

  First, a case where a front-side wall projection image using the maximum value projection method as projection processing is generated will be described. In order to generate a front-side wall projection image, ray tracing is performed along the viewing direction. The line-of-sight direction referred to here is, for example, the line-of-sight direction in the entire area projection image shown in FIG. This line-of-sight direction is indicated by an arrow on the front side in FIG. In the projection processing for generating one pixel of the projection image, the pixel value of the three-dimensional image (volume image) is traced along one of the arrows (projection line), and the pixel on the projection line is the most pixel A process for specifying a pixel value of a pixel having a high value is executed. In the normal MIP method, when the region of the three-dimensional lumen image is exited, the projection processing along one projection line is terminated (FIG. 7A). In this embodiment, however, the termination is determined. While searching for the maximum value of the three-dimensional image along one projection line, referring to the binary image of region e (showing the region including the stomach wall), once inside the region e, When it goes out of the region e, the projection is terminated (FIG. 7B).

  When the projection processing of this embodiment is stopped, even when average value projection is performed as the projection processing, only the structure of the front surface of the wall is projected, and the positions of the white portion and the black portion can be grasped from the projection image. However, when the average value projection is performed as in the conventional case of FIG. 8, the structure of the stomach wall cannot be grasped from the projection image because both the front and rear wall structures are projected.

  On the other hand, in the present embodiment, the region including the wall structure is extracted by the threshold processing and the shape calculation processing, and the projection processing is terminated at the trailing edge of the extracted region, and therefore, as shown in FIGS. 9A and 9B. As described above, since the projection images in which only the structure of only one stomach wall in the front or back is separated can be individually generated, the structures of the front and rear stomach walls can be grasped from the projection image.

  Based on the above method, it is also possible to adopt a method in which the projection start point is set as the first entry into the extracted region e during the projection process along the projection line. When this method is used, the pixel value of the structure in front of the stomach wall is not involved in the projection image, so that it is possible to create a projection image that more accurately reflects the pixel value of the stomach wall portion. In addition, since the area where the projection process is performed is greatly reduced, the projection process can be performed at high speed.

  Gray scale dilation may be used as another projection processing procedure. In order to explain the basic concept of this method, the method of generating a similar image was explained by referring to the binary image along the projection straight line and terminating the projection at the trailing edge of the region. There may be other procedures besides this Act.

  First, when gray scale dilation is used in the image processing step, the pixel value of the image after gray scale dilation is compared with the threshold values Tpu and Tpl instead of the determination of the area trailing edge based on the binary area image. Thus, a similar image can be generated.

  Further, as another projection processing procedure, the projection stop processing may be performed using the depth map illustrated in FIG. 10 (an image having a projection depth as a pixel value). Even in the case of using a binary image, instead of determining the projection processing stop condition (censoring condition) for each projection straight line, a depth map of the trailing edge of the region e is temporarily created, and this depth map is referred to. There is also a way to abort (or start) the projection. Even when this depth map is used, discontinuity occurs in the stomach wall on the front side as shown in FIG. 10, and the pixel search range reaches the stomach wall on the back side. Image) cannot be separated. That is, the stomach wall image on the near side and the stomach wall image on the far side overlap with a single projection image. Therefore, from the stomach wall region extracted by the threshold processing shown in FIG. 11 (a), the back (back side) stomach wall region is removed as shown in FIG. 11 (b), and the form as shown in FIG. 11 (c) is obtained. By performing dilation processing (referred to as expansion or expansion processing) as processing, and stopping the projection processing when the projection search point deviates from the expansion region, it is possible to separate the projection images on the front side and the back side. The actual projection stop process is stopped when the depth of the projection search point reaches the trailing edge line of the expansion region shown in FIG. In the method using the depth map, the transformation processing (region division, morphological computation, addition, etc.) of the two-dimensional depth map is performed instead of the three-dimensional morphological computation, so that the processing time for image generation can be significantly reduced. This is one of the highly preferred embodiments of the present invention.

  As projection processing of the present embodiment, in addition to maximum value projection (MIP), minimum intensity projection (see FIG. 13A), average projection (average projection) (see FIG. 13 b)), an addition image (max + min) of the maximum value projection image and the minimum value projection image (see FIG. 13C) can be selected. As the added image, an image having a larger contrast than that of each of the maximum value projection image and the minimum value projection image can be generated.

  In the projection processing, an appropriate preprocessing is effective for improving the visibility of the object (here, the stomach wall). Since the average value projection image adds the areas before and after the object to be viewed, there is a problem that the contrast of the object to be viewed becomes relatively small. In addition, the maximum value projection and the minimum value projection have a problem that if the luminance difference between the object and its background is small, the object is erased by the noise before and after it, and the object cannot be seen at all. This problem can be solved by performing the following process on the three-dimensional image before creating the projection image.

(1) First, an expansion operation or an erosion operation (erosion) is performed on the extracted stomach wall region (e).
(2) Next, a distance image (depth image) outward from the stomach wall region (e) is calculated using distance conversion processing.
(3) A weight k (r) is calculated for each pixel of the three-dimensional image. For example, using the parameter a for the weight,
k = d / (d + a)
Or
k = exp (− (d / a) ² )
Can be used. These weights are “1” on the extracted stomach wall and decrease to a value close to “0” as the distance from the stomach wall increases.
(4) Multiply the three-dimensional image by the weight k of (3) for each pixel.

  After these processes, an average value projection and a maximum value projection process are performed. FIG. 14A and FIG. 14B are examples in which an image is improved by this luminance conversion processing. FIG. 14A shows a projection image that is not subjected to the pre-process for luminance conversion, and a small change in luminance due to the contrast agent adhering to the stomach wall cannot be observed, but in the projection image that has been subjected to the pre-process for luminance conversion in FIG. These luminance changes are stored.

  The partial projection image relating to the stomach wall on the near side of the projection processing generated as described above and the partial projection image relating to the stomach wall on the back side are configured and displayed on the screen illustrated in FIG. 15 by the image display processing unit 4. These partial projection images are displayed together with options for the division method by the operator and options for the projection method related to generation of the partial projection image. Options for the division method include front side (near side, ventral side) / back side (back side) division in FIG. 9, multiple plane division in FIG. 17 described later, curved surface division in FIG. 18 described later, and FIG. Automatic multi-plane division is prepared. Here, the presence / absence of display of a front projection image as a whole area projection without a conventional partial projection (projection stop process) is also included. Further, for each of the front projection and each partial projection (in FIG. 15, the dorsal projection and the ventral projection), the maximum projection method (maximum), the minimum projection method (minimum), the average projection (average), An added image (max + min) can be selected.

  Furthermore, the screen includes a line-of-sight movement operation button, a display target range movement operation button, a display target range expansion / reduction operation button, a gray level GL high / low operation button, a window width WW wide / narrow operation button, and binarization. An operation button for selecting the number of threshold values from 1 to 4 at the time of operation, an interlocking button for selecting whether or not to automatically determine the threshold value, and an operation button for increasing and decreasing the distance of dilation processing are displayed.

  In the projection processing unit 3 according to the present embodiment, in the front and rear wall surface divided projection image generation processing portion 31 of FIG. 1, a stop condition for the projection processing is determined using the expansion region, and thereby a plurality of partial projection images related to a plurality of portions, for example A method of generating a partial projection image related to the stomach wall portion on the side and a partial projection image related to the stomach wall portion on the back side, and a projection target region of the three-dimensional image by the plane division projection image generation processing unit 32 to be divided into a plurality of partial regions in a plane Then, each partial area is individually projected (plane division projection processing method), and the projection target area of the 3D image by the curved divided projection image generation processing unit 33 is divided into a plurality of partial areas by curved surfaces. The method of projecting partial areas individually (curved surface division projection processing method) and the overlapping of stomach wall surfaces by the automatic wall surface division projection image generation processing part 34 are automatically determined to prevent partial projection. Method of generating an image (automatic segmentation method) and is selective by the operator. These plane division projection processing method, curved surface division projection processing method, and automatic division method will be described in order.

  In the plane division projection processing method, there are a case where division is performed using a single division plane and a case where division is performed using a plurality of division planes. When dividing by a single dividing plane, first, as shown in FIG. 16A, three points are pointed by a normal projection image. Usually 3 points, but more or less. For each of the three points, the depth of the trailing edge of the inflated region with respect to the stomach wall on the near side in FIG. 12 in the morphological operation processing unit 24 in FIG. 1 is determined (FIG. 16B). The division plane of the projection area is determined from the specified three points. In the case of three points, the plane passing through the three points is uniquely determined. In the case of one or two points, the plane is determined by the minimum norm method. When there are four or more points, the plane is determined by the least square method. Instead of a plane equation, a curved surface instead of a plane can be determined by determining the parameters of the curved surface equation. A partial projection image (FIG. 16D) in which the partial area before the division plane is the target of the projection process and a partial projection image in which the partial area behind the division plane is the target of the projection processing (FIG. 16C). )) And individually.

  When dividing by a plurality of dividing planes, one dividing plane is determined as in the example of FIG. When the division plane addition button is pressed, a new division plane is generated in parallel with the already displayed division plane. The depth of the newly generated division plane is arbitrarily changed. Further, when the surface addition button is pressed, the above is repeated to set a plurality of surfaces (FIGS. 17A and 17B). The depth relations of the surfaces are aligned (sorted), and divided projection images of the respective regions divided into the region in front of the foremost surface, the space between adjacent surfaces, and the region in the back of the back are generated and displayed (FIG. 16). (C)). Since two images are generated in the projection stop process and the division process on a single division plane, in the case of a divided image of the front projection image of the stomach wall (in this case, usually, there are two overlapping surfaces of the stomach wall). It is valid. However, in the case of a side projection image, since more than two surfaces overlap, it is not possible to display all the surfaces by the projection stop process or the division process on a single division plane. According to the three or more partial projection images divided by the plurality of planes, since the display is divided into more than two regions, all the wall surfaces that overlap in the side projection image can be displayed, and diagnosis omission can be reduced. .

  Generation of a curved surface divided projection image by the curved surface divided projection image generation processing unit 33 is effective for dividing and displaying a side projection image. First, a captured image from the side is acquired and a front projection image is displayed (FIGS. 18A and 18B). A curve is designated on the front projection image in the same manner as in the method of creating the curved section transformation (curved MPR) (FIG. 18B). If this curve is extended in the depth direction of the front projection image, a curved surface is designated. One surface of this curved surface is defined as the front surface and the other surface is defined as the back surface. As an example, the convex direction is the front.

  At each point on the curved surface, the projection direction is a direction orthogonal to the curved surface, and the projection processing is started on the front surface side and the back surface side starting from the curved surface, so that two projected images (FIG. 18 ( c)). The method of creating the censored projection image is as shown in FIG. Then, the projection image is displayed. An example of the display screen can be the one shown in FIG.

  As a curve tracing method, manual tracing may be used, and an automatic tracing method used for blood vessel centerline tracing may be applied.

  In the above explanation, a two-dimensional curve is specified on the projection map, but in this case, if the viewing direction is changed, the specified curve can no longer be used, so if the curve is not specified again, The divided projection image cannot be updated. However, by using a three-dimensional curve, it is possible to create a divided projection image with a changed line of sight without re-specifying the curve. It can be greatly reduced.

For example, in the case of a front projection image, the automatic wall surface division by the wall surface automatic division projection image generation processing unit 34 is performed every time the line-of-sight direction of the conceptual division projection image of the wall surface division that solves the overlap of the stomach wall with respect to the projection direction is changed. Switching between the front and rear wall surface division method by the processing unit 31 and the multiple plane division projection method by the processing unit 32 in the case of a side projection image is troublesome in operation. In the case of the curved surface projection method by the processing unit 33, it is possible to create divided projection images in various line-of-sight directions, but an operation of specifying a curve is necessary, and it cannot be said that the operation is simple.

The wall surface automatic division projection method solves these problems, automatically determines the number of overlaps that differ depending on the line-of-sight direction, and creates divided projection images of that number.
Here, a case of a side projection image of the stomach wall will be described as an example. As shown in FIG. 19 (b), it is necessary to divide the stomach wall into four (A, B, C, D) portions so as not to overlap. Although described in detail below, for simplicity, based on the extraction result of the stomach wall region, the extracted connected region e is divided into, for example, four. Projection processing is performed for each of the divided areas, and four projected images A, B, C, and D are generated and displayed. Since the projected image displayed in this way is a projected image in which the problem of overlapping has been solved, there is an effect of improving the ease of diagnosis and diagnostic accuracy, and in this method, an operation in which an operator designates a curve is performed. Since it is not necessary, the operation for creating the divided projection image can be extremely facilitated, and there is an effect that a practical device can be provided for diagnosis. Hereinafter, the procedure of automatic wall surface division will be described in detail.

  The connected region e is extracted by the region extracting unit 2 (FIG. 20A) and resampled. Match the line-of-sight direction with the z-axis of the resampled image data. It is better to reduce the number of pixels. For each point on the projection plane, a pixel value is searched for in a direction parallel to the line-of-sight direction (along the projection straight line). The number of times of entering the area e is counted and recorded in association with each point of the area e (or resampled data) (FIG. 20B). Originally, we want to divide only the folded part (the part where the projected straight line is on the tangent plane of the stomach wall) into different areas. However, in this state, a count value different from 2, 3, and 4 may be assigned even though there is no aliasing as in the leftmost surface.

  As a labeling of the connected area by the count value, in this state, the same count value is present regardless of being connected. In the subsequent processing, since it is necessary to distinguish each connected area, the connected areas are labeled (numbered). For example, as a result, labeling is performed on six regions a, b, c, d, e, and f. Next, based on the labeling, the false boundary of the intersection count due to the folding or end of the previous surface is recognized. If the front surface is folded, there is a boundary with different count values even if the rear surface is not folded. However, it can be recognized as a boundary where the count value differs by 1 on the previous surface (see FIG. 21). Therefore, if there is a boundary whose count value is different by 1, there should be a boundary on all the faces after it, and those false boundaries will be recorded in the table as a correction schedule that the count value should be corrected . For example, the region e and the region f in FIG. 20B are false boundaries.

  Even when the front surface is a single part, there is a boundary of count values on the rear surface. The end portion can be recognized by the fact that the projection straight line itself continues with the background portion, but the adjacent pixel once becomes a count value of 1 or more and the adjacent pixel returns to the background again. At such an end, there should be a boundary on all the faces after that, and those false boundaries are recorded in the table as a correction schedule that the count value should be corrected (see FIG. 22). . For example, regions e and d are false boundaries.

  Next, the count value needs to be corrected. In the process of recognizing the false boundary of the count value, the count value is not actually corrected and only the false boundary is recorded in the table. Which area is to be corrected to which count value is determined after all false boundaries have been recognized. In the above example, as illustrated in FIG. 23, the regions e and f and the regions e and d are determined to be false boundaries. First, of the areas e and f, the area e having a smaller count value is corrected on the table to a value having a larger count value (count value 4). The region e and the region d are similarly analyzed, and the count value of the region d is corrected to 4 (on the table). The count value corrected on the table may be corrected on the actual data, or may be simply referred to the table when displayed.

  For the four areas of count values 1, 2, 3, and 4, partial projection images of only those partial areas are created and displayed. For example, as shown in FIG. 28, the partial projection images on the four side surfaces are the whole area projection image from the front, the whole area projection image from the side, the partial projection image from the front regarding the stomach wall part on the near side, the stomach wall part on the back side And is displayed on the same screen as the partial projection image from the front.

  The projection image generation unit 3 generates a development projection image in the development projection image generation processing unit 35. The development projection image generation processing unit 35 enables generation of a development drawing based on the three-dimensional approximate center line of the lumen. In the developed projection image, the entire stomach wall is displayed as a single image, and in addition to the effect of facilitating the search for abnormal sites, the censored processing on the stomach wall surface of the projection is performed when generating the developed projection image. The projection image is not deteriorated due to the structure after the stomach wall, and a developed projection image suitable for diagnosis is generated more than the stomach wall.

  A procedure of the developed projection image generation process will be described. It should be noted that either a case where the three-dimensional approximate center line of the lumen is traced manually or an automatic trace may be used.

  As shown in FIG. 24A, the front projection image is displayed as a projection image for the trace operation. For example, a substantially center line of the stomach is manually traced as a lumen on the front projection image. Actually, by specifying several control points on the front projection image, a curve connecting them is automatically drawn. Subsequently, as shown in FIG. 24B, a side projection image is displayed, and on this side projection image, the depth of the control point is adjusted, and a three-dimensional curve is determined as the approximate center line of the stomach. .

  As shown in FIG. 24 (c), a projection process is performed radially along the radial direction around the determined approximate center line of the stomach to generate a developed projection image. In the projection process, the projection process is stopped (canceled) at the rear edge of the connection region e of the stomach wall as shown in FIG. As shown in FIG. 25, a developed view is generated with the vertical axis being the circumferential angle around the central axis and the horizontal axis being the position in the longitudinal direction of the central line.

  In the development view display, the display of the stomach wall orientation and the superimposed display of the area requiring attention are effective. In the developed projection image generation processing unit 35, first, the detailed uneven structure of the stomach wall surface is analyzed, and a region where there is a possibility of abnormality (a region requiring attention) is specified. It is determined to which image of the above-described partial projection image the specified region is to be superimposed. An image in which a partial projection image and a graphic indicating a region requiring attention are superimposed is displayed. As shown in FIG. 26, an image in which a normal projection image (a front projection image and a side projection image of the whole projection) and a graphic indicating a caution area are superimposed is displayed. As shown in FIG. 26, the cursor is displayed on the front projection image and the side projection image of the whole projection. As shown in FIG. 26, the partial projection image and the developed projection image are displayed at the same time, and the cursor is linked by aligning the position of the partial projection image and the developed projection image. When an operation of moving the cursor on one image is performed, the position of the cursor on the projection display, the divided projection image, and the unfolded projection is updated according to the operation.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the components without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

The figure which shows the structure of the medical image processing apparatus by embodiment of this invention. The figure which shows an example of the three-dimensional image generator of the three-dimensional image machine billion of FIG. The figure which shows the outline | summary of the image processing procedure by this embodiment. The figure which shows the process sequence of the image process step of FIG. FIG. 5 is a supplementary explanatory diagram of the processing procedure of FIG. 4. FIG. 4 is a schematic explanatory diagram of a projection processing step in FIG. 3. The figure which shows the projection stop conditions of the projection process step of FIG. The figure which shows the average value projection of the projection process step of FIG. The figure which shows the two partial projection images produced | generated by the projection process step of FIG. Explanatory drawing of the depth map used for other projection stop conditions in the projection process step of FIG. The figure which shows the production | generation procedure of the depth map of FIG. The figure which shows the projection stop line by the depth map of FIG. The figure which shows the various projection image examples by this embodiment. The figure which shows the pre-processing effect of the projection process step of FIG. The figure which shows an example of the display screen by this embodiment. FIG. 3 is a supplementary explanatory diagram of division projection processing using one plane in the plane division projection image generation processing unit of FIG. 1. FIG. 3 is a supplementary explanatory diagram of division projection processing using a plurality of planes in the plane division projection image generation processing unit of FIG. 1. FIG. 3 is a supplementary explanatory diagram of division projection processing in the aspect division projection image generation processing unit of FIG. 1. FIG. 2 is a supplementary explanatory diagram of wall surface automatic division processing in the wall surface automatic division projection image generation processing unit of FIG. Detailed explanatory drawing of the wall surface automatic division | segmentation process of FIG. Explanatory drawing of the wall surface automatic division | segmentation rule of FIG. Explanatory drawing of the wall surface automatic division | segmentation rule of FIG. Explanatory drawing regarding correction of the wall surface automatic division | segmentation process of FIG. FIG. 3 is a supplementary explanatory diagram of a development projection process in the development projection image generation processing unit of FIG. The figure which shows an example of the expansion | deployment projection image by the expansion | deployment projection image generation process part of FIG. The figure which shows the example of an orientation display with respect to the projection image by the image display process part of FIG. The figure which shows the example of an orientation display with respect to the expanded view by the image display process part of FIG. The figure which shows the example of a simultaneous display screen of the projection image of the front and side by the image display process part of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Three-dimensional image storage part, 2 ... Area extraction part, 3 ... Projection image generation part, 4 ... Image display process part, 5 ... Image display part, 21 ... Filter process part, 22 ... Threshold determination process part, 23 ... Threshold value Processing unit 24 ... Morphological calculation processing unit 25 ... Connection region selection processing unit 31 ... Front and rear wall surface division projection image generation processing unit 32 ... Planar division projection image generation processing unit 33 ... Curved surface division projection image generation processing unit 34 ... wall surface automatic division projection image generation processing part, 35 ... developed projection image generation processing part.

Claims (12)

A storage unit for storing three-dimensional image data relating to a part including a lumen;
An extraction processing unit for extracting a lumen region including the lumen from the three-dimensional image data;
A medical image processing apparatus, comprising: a projection image generation unit configured to generate a plurality of partial projection images related to a plurality of partial regions constituting the extracted lumen region from the three-dimensional image data.   The medical image processing apparatus according to claim 1, wherein the projection image generation unit generates a plurality of partial projection images related to a plurality of partial regions in which the extracted lumen regions do not overlap in the line-of-sight direction of the projection processing.   The projection image generation unit generates a partial projection image related to a partial region including a near-side wall region and a partial projection image related to a partial region including a back-side wall region with respect to the line-of-sight direction of the projection processing. The medical image processing apparatus according to claim 1.   The medical image processing apparatus according to claim 1, wherein the projection image generation unit generates a plurality of partial projection images related to a plurality of partial regions obtained by dividing the extracted lumen region by a plane.   The said projection image generation part produces | generates the some partial projection image regarding the some partial area | region obtained by dividing | segmenting the extracted said lumen | bore area | region into a curved surface along a substantially central axis. Medical image processing apparatus.   The extraction processing unit includes a threshold processing unit that extracts a region from the three-dimensional image data by threshold processing, and an expansion calculation processing unit that generates the lumen region by performing expansion processing on the extracted region. The medical image processing apparatus according to claim 1.   The medical image processing apparatus according to claim 1, wherein the projection image generation unit generates an addition image of a maximum value projection image and a minimum value projection image related to a corresponding partial region as the partial projection image.   The medical device according to claim 1, further comprising a display unit configured to display the plurality of generated partial projection images together with options of a division method related to the partial area and projection method options related to generation of the partial projection image. Image processing device. A storage unit for storing three-dimensional image data relating to a part including a lumen;
An extraction processing unit for extracting the wall region of the lumen from the three-dimensional image data by threshold processing;
An expansion processing section for expanding the wall region;
A projection image generation unit that generates a plurality of partial projection images by projecting the three-dimensional image data from a plurality of directions, assuming that a projection search point first exits the wall region subjected to the expansion processing; A medical image processing apparatus comprising the medical image processing apparatus. A storage unit for storing three-dimensional image data relating to a part including a lumen;
An extraction processing unit for extracting the wall region of the lumen from the three-dimensional image data by threshold processing;
An expansion processing section for expanding the wall region;
A projection image generation unit that generates a plurality of partial projection images by performing projection processing on the three-dimensional image data from a plurality of directions on the condition that a projection search point reaches the inner edge depth of the wall region subjected to the expansion processing A medical image processing apparatus. A storage unit for storing three-dimensional image data relating to a part including a lumen;
The value of the projection processing performed along the radial direction from the substantially central axis of the lumen region including the lumen is the position on the substantially central axis with the circumferential angle around the approximate central axis as the vertical axis. A developed image generating unit that generates a developed image distributed as the horizontal axis from the three-dimensional image data;
The developed image generation unit includes an extraction processing unit that extracts a wall region of the lumen from the three-dimensional image data by threshold processing, an expansion processing unit that performs expansion processing on the wall region, and the wall region that has undergone expansion processing. A medical image processing apparatus, wherein the projection processing is performed under a projection stop condition that a projection search point first exits. A storage unit for storing three-dimensional image data relating to a part including a lumen;
The value of the projection processing performed along the radial direction from the substantially central axis of the lumen region including the lumen is the position on the substantially central axis with the circumferential angle around the approximate central axis as the vertical axis. A developed image generating unit that generates a developed image distributed as the horizontal axis from the three-dimensional image data;
The developed image generating unit includes an extraction processing unit that extracts a wall region of the lumen from the three-dimensional image data by threshold processing, an expansion processing unit that performs expansion processing on the wall region, and an expansion processing unit that performs expansion processing on the wall region subjected to expansion processing. A medical image processing apparatus that performs the projection processing with a projection stop condition that a projection search point reaches an inner edge depth.

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