JP4193201B2 - Organ excision area extraction and display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an organ excision region extraction / display apparatus, and more particularly to a technique for displaying an excision region for favorably excising a lesion such as a tumor in an organ.
[0002]
[Prior art]
In recent years, an image obtained by a medical image diagnostic apparatus such as an X-ray imaging apparatus, an X-ray CT apparatus, or an MRI apparatus has been actively used not only for diagnosis but also for treatment.
[0003]
Treatment includes catheterization for treating a diseased part by inserting a catheter into a subject, and surgical operation for excision of the diseased part by conventional incision. In a surgical operation, it is common to obtain an image of an affected area with a medical image diagnostic apparatus and determine a part to be excised before the operation. As a display image for determining a part to be cut, a two-dimensional image or a three-dimensional image formed by stacking two-dimensional images is used. This is because the resected portion is determined intuitively because it is closer to the shape of the human body.
[0004]
On the other hand, a conventional method for extracting an organ on a two-dimensional image and determining an excision part is manually performed based on anatomical knowledge.
[0005]
In recent years, research on automatic extraction of specific organs has become active. However, doctors determine and recognize area classification and identification within specific organs based on anatomical knowledge.
[0006]
Although there is a method for extracting a specific region in a single organ, in an actual clinical site, the organ is not cut off on a display image with a geometric plane or curved surface. Simulation results are not very useful in clinical settings.
[0007]
Therefore, a method for extracting a specific region of an organ partially controlled by a blood vessel based on blood vessel running information in a single organ as disclosed in Japanese Patent Application Laid-Open No. 2001-283191 has been proposed. Since it is based on anatomical information, a result very similar to a specific region judged by a doctor is obtained, and the simulation accuracy as a pre-organectomy plan is dramatically improved. For example, in an operation for removing liver cancer, an operation method consistent with the above simulation method can often be employed.
[0008]
[Problems to be solved by the invention]
However, in actual clinical practice, a tumor such as cancer does not exist only in a region surrounded by the above-described method that matches the anatomical knowledge, but may exist at the boundary portion. When excision and excision are attempted with the above-described method for a tumor that is present across the border of an area, the excision area is enlarged, and the burden on the patient is increased as an operation. As a result, the same method as the simulation may not be adopted.
[0009]
In addition, even if a tumor exists in the region surrounded by the above technique, there is a case where an appropriate surgical margin cannot be secured and cannot be applied to an actual operation.
[0010]
Furthermore, the liver function of the patient is originally lowered due to cirrhosis and the like, and the method similar to the simulation that is usually applicable makes it difficult to secure the liver function after the operation, and it is difficult to perform the actual operation. There are cases where it is not applicable.
[0011]
In this case, a partial resection in which the doctor performs a resection while sequentially judging the region that is partially controlled by the blood vessel during the operation, or a combination of the method similar to the simulation and the partial resection is adopted. There are many.
[0012]
In partial resection, doctors identify the ablation area non-systematically while examining the position, size, blood vessel position, etc. of the tumor using an echo during the operation. For example, in the case of partial resection of the liver, the diameter of the tumor, the start position of resection (separation), and the position of a blood vessel that serves as a guide are marked as markers that serve as a guide for surgery. Based on this information, resection is performed while using echo together during the operation.
[0013]
Therefore, with the current simulation method, it is not possible to perform excision simulation with high accuracy for a tumor present at the above position or a patient with low liver function.
[0014]
The present invention has been made in view of such circumstances, and it is possible to extract an excision region of an organ suitable for simulation at the time of excision using the characteristics of an organ with complex blood vessels such as the liver. Another object of the present invention is to provide an organ excision area extraction / display device that can display the excision area in an identifiable manner.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, the organ excision area extraction / display apparatus according to claim 1 extracts a lesion area in an organ using an image of a subject and sets a lesion area including at least the lesion area. And means for detecting running information of a plurality of vessels outside the lesion area using the image of the subject, and including the lesion area based on the lesion information and the running information of the plurality of vessels, and means for determining the ablation region to the surface of the organ does not include the plurality of vessels, areas spherically from the center or centroid of the lesion area to contact with one of the outwardly plurality of vessels And a means for determining an area in contact with the expanded spherical area as an ablation area and a display means for displaying at least the ablation area of the organ in an identifiable manner.
[0016]
In the present invention, a lesion such as a tumor in an organ is extracted using an image of a subject, and a lesion area including at least the lesion is set. The extraction of the lesioned part can be performed based on the size of the pixel value in the image showing the organ, and the lesioned area including the lesioned part can be set in consideration of the surgical margin or the like. it can.
[0017]
Subsequently, traveling information of a plurality of vessels outside the lesion area is detected using the image of the subject. The plurality of detected vessels are vessels that are close to the lesion area among the vessels outside the lesion area and have a diameter that is not less than a predetermined diameter. Is the direction vector of the vessel at.
[0018]
Next, an ablation region that includes the lesion region and does not include the plurality of vessels is determined based on the lesion region and the travel information of the plurality of vessels. As a method for determining the ablation area, for example, the lesion area is formed in a spherical shape, a substantially cone including the direction vector of the vessel in contact with the sphere is obtained, and the abbreviated cone is defined as an ablation area (conical resection area) . Note that a region surrounded by the apex of the substantially cone and the lesion region is not included in the ablation region.
[0019]
As another method of determining the resection area, for example, the lesion area is formed into a spherical shape, and the organ position appropriately designated in consideration of the surface position of the organ that is the shortest distance from the lesion area or the ease of surgery. A substantially cone centered on a line segment connecting the surface position and the center of the lesion area, and including the lesion area and having a predetermined apex angle (for example, 60 degrees), is defined as an ablation area. The predetermined apex angle can be set as appropriate, but the apex angle is limited so that the vessel is not included in at least a substantially conical resection region.
[0020]
When the organ resection area is determined as described above, at least the resection area is displayed on the display means so as to be identifiable. As the display method, the boundary between the ablation region and the non-ablation region is displayed so that the ablation region and the non-ablation region can be distinguished from each other, or only the ablation region is displayed.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
A preferred embodiment of an organ resection area extraction / display apparatus according to the present invention will be described below in detail with reference to the accompanying drawings.
[0022]
As shown in FIG. 1A, a plurality of tomographic images 11 obtained by an image diagnostic apparatus capable of three-dimensional measurement such as an X-ray CT apparatus and an MRI apparatus are stacked, and a stacked tertiary as shown in FIG. The original image 12 is used, and the processing target is three-dimensional. The stacked three-dimensional image 12 includes a liver tissue, portal vein, vein, tumor, and the like, and is displayed on a monitor as a pseudo three-dimensional image that is projected and shaded on a two-dimensional projection surface (not shown). Is done.
[0023]
FIG. 2 is a flowchart showing the procedure of organ excision region extraction display according to the present invention.
[0024]
The region specifying process 20 of the present invention includes a region of interest extracting process 21, a distance value converting process 22, a thinning process 23 or a surface pixel detecting process 24, a parameter automatic calculation setting process 25 or a parameter manual calculation setting process 26, and an ablation area specifying process. 27 and an excision region excision process 28.
[0025]
A region-of-interest extraction process 21 is performed on the accumulated three-dimensional image data read from the image diagnostic apparatus, and a region of interest (target organ: for example, liver parenchyma, tumor, portal vein) is extracted. A distance value conversion process 22 is performed on the extracted portal vein, the diameter of the portal vein and the like are measured, and a thinning process 23 or a surface pixel detection process 24 for obtaining a core line of the portal vein is performed.
[0026]
Next, the concept of the parameter automatic calculation setting process 25 is shown in FIG.
[0027]
The center or center of gravity 32 of the extracted tumor 31 and the radius or maximum diameter 33 of the tumor 31 are obtained. A spherical region expansion (surgical margin region) 34 is performed toward the outside of the tumor 31, and the expansion is stopped when contacting a vessel such as the portal vein 35, for example. Information on the diameter of the blood vessel obtained from the distance value conversion process 22 is used to determine whether or not the blood vessel is for stopping expansion. If it comes into contact with a vessel that is thinner than a specified diameter (for example, 1 mm or less), the region expansion is continued.
[0028]
A value obtained by subtracting the diameter 33 of the tumor from the diameter 36 of the spherical area 34 expanded from the center of the tumor 31 is defined as a safe area width (surgical margin) 37 in the operation.
[0029]
Next, FIG. 4 shows a concept of an ablation area specifying process 27 for specifying an ablation area from a vessel existing in the vicinity of a tumor.
[0030]
As shown in FIG. 4 (a), the core line constituting pixels 41 and 42 in the blood vessel 35 subjected to the thinning process 23 closest to the tumor 31 are detected, and the core line constituting pixels before and after the extraction are extracted. The direction vectors 43 and 44 are calculated as shown in FIG. A conical region having an angle formed by these direction vectors 43 and 44 and in contact with the surgical margin region 34 is defined. It is assumed that a region 46 surrounded by the apex 45 of the cone and the surgical margin region 34 is not included in the ablation region.
[0031]
Accordingly, the ablation region is a region obtained by combining the surgical margin region 34 and the remaining region 47 of the cone. The actual ablation region is determined so that the surface 51 of the liver parenchyma becomes the bottom of the cone as shown in FIG.
[0032]
When the edge (that is, the separation start position) 61 of the bottom surface of the conical region existing on the liver surface is displayed on the liver surface, it is as shown in FIG. The separation start position 61 is displayed as a line (solid line, dotted line, etc.) or a colored surface. Further, by displaying the tumor together with the projected tumor image 62 projected on the liver surface 51, the same effect as the marking performed in the actual operation can be obtained.
[0033]
An example of a judgment formula for the surgical margin region 34 is shown based on FIGS. 3 and 4.
[0034]
Information on the diameter of the vessel is obtained in advance by the distance value conversion process 22. Assuming N is the minimum diameter of the vessel to be treated and not preserved. The constituent pixel of the vessel 35 is V, the core line constituent pixel of the vessel is C, and the diameter of the blood vessel at the core line portion is C (n) (n: the number given to the core wire).
[0035]
The center or the center of gravity 32 of the tumor 31 is set as T, and the liver parenchyma pixel or vascular pixel L (i) (i: generation number when searching radially from the tumor center) is sequentially searched in a spherical shape. Assuming that the three-dimensional distance at that time is TL (i), the diameter R (diameter 36 in FIG. 3) of the resection region (sphere) including the tumor 31 and the determination condition are as follows:
[Expression 1]
R = TL (i-1) (L (i) = V & C (n) ≧ N)
It becomes. Actually, there is no surgical margin area set at the very edge of the vessel as in parameter i-1, and it is manually set by an operator with anatomical knowledge, or the position and diameter of the tumor, and the tumor center or tumor. The parameter i-1 is automatically changed using a calculation formula or the like based on statistics based on the distance from the edge to the vessel. Furthermore, since the surgical margin 37 (see FIG. 3) is set to about 10 mm in general surgery, the spherical region expansion 34 may be stopped when an appropriate surgical margin 37 is obtained. .
[0037]
In the excision region excision process 28, for example, the excision region surrounded by the surgical margin region 34, the conical region 47, and the liver substantial surface 51 is extracted starting from the tumor center 32, and the pixel value of the excision region is determined as the pixel of the non-ablation region. By replacing with a value different from the value, it is possible to identify and display. Moreover, the same effect as ablation can be obtained by displaying a three-dimensional image in which the pixels in the ablation region are not displayed.
[0038]
Next, FIG. 7 shows a method for setting an ablation region when parameters are given manually.
[0039]
A cone centering on a line segment connecting the center of gravity 32 of the tumor 31 and the tumor center 71 projected onto the liver surface 51, and the apex angle θ of the apex 45 of this cone becomes a predetermined angle (for example, 60 degrees), A conical region 47 in contact with the surgical margin region 34 and having a bottom surface defined by the surface of the liver is defined as an ablation region. It is assumed that the region surrounded by the apex 45 of the cone and the surgical margin region 34 is not included in the ablation region.
[0040]
The predetermined apex angle θ can be set as appropriate, but the apex angle is limited so that the vessel 35 is not included in at least the conical resection region. Further, the position of the tumor center 71 when projected onto the liver surface 51 can be set as appropriate in consideration of the position closest to the liver surface 51 from the tumor 31, the traveling direction of the blood vessels, the position where surgery is easy, and the like. is there.
[0041]
From the ablation area determined as described above, the tumor center 71 and the tumor projection image 62 can be displayed, and the separation start distance 72 can be given. When displayed as a three-dimensional image, an image similar to FIG. 6 can be created.
[0042]
FIG. 8 is a schematic diagram showing a hardware configuration of an organ resection area extraction / display apparatus according to the present invention.
[0043]
This organ excision area extraction and display device is composed of a central processing unit (CPU) 82, a main memory 80, a magnetic disk 81, a display memory 83, a display 84, a controller 85, a mouse 86, a keyboard 87, and a common bus 88. Yes.
[0044]
Each tomographic image of the subject acquired from the X-ray CT apparatus is stored on the magnetic disk 81, and the CPU 82 performs predetermined processing according to the projection display software (FIG. 2) of the main memory 80. In this processing, input / output processing and processing operations using the mouse 86 and keyboard 87 attached to the controller 85 are performed. The stacked three-dimensional image and the processing result are displayed on the display 84 via the display memory 83, and the processing shown in FIG. 2 is performed using the operation of the operator, and an image that meets various conditions is displayed. The processing result and display contents are stored in the magnetic disk 81 and used for redisplay.
[0045]
Note that the stacked three-dimensional image is not limited to that obtained from the X-ray CT apparatus, but may be obtained by another image diagnostic apparatus such as a magnetic resonance imaging apparatus or an ultrasonic diagnostic apparatus. In addition to the liver described in this embodiment, the target organ can be applied to many parts of the human body.
[0046]
【The invention's effect】
As described above, according to the present invention, it is possible to extract an ablation region of an organ so as not to cut a vessel having a predetermined diameter or more using the characteristics of an organ having a complicated blood vessel such as a liver. The ablation area can be displayed in an identifiable manner. For example, when performing liver resection simulation, etc., it is possible to handle more cases, enabling surgical planning, resection simulation, calculation of resection rate, and three-dimensional visualization in a more clinical form. . It is also possible to confirm on the two-dimensional image whether or not the three-dimensionally specified resection area is appropriate.
[Brief description of the drawings]
FIG. 1 is a diagram showing the relationship between tomographic images and data. FIG. 2 is a flowchart used to explain the outline of the procedure for extracting and displaying an organ excision area according to the present invention. Figure used to explain the definition of relationship, tumor, and surgical margin. [Figure 4] Figure used to explain the procedure for determining the resection area for resecting the tumor. FIG. 6 is a diagram used for explaining a display example of an ablation region by simulation. FIG. 7 is a diagram for explaining a region determination method when a parameter for determining the ablation region is manually given. FIG. 8 is a diagram showing a hardware configuration example of an organ resection area extraction / display apparatus according to the present invention.
DESCRIPTION OF SYMBOLS 11 ... Tomographic image, 12 ... Stacked three-dimensional image, 31 ... Tumor, 32 ... Tumor center or center of gravity, 33 ... Tumor radius, 34 ... Surgical margin area, 35 ... Vascular (portal vein, vein, artery, etc.), 36 ... Resection radius around the tumor including the surgical margin, 37 ... Surgical margin, 41,42 ... Pixel constituting pixels of the vessel, 43,44 ... Vector indicating the direction of the branch of the vessel, 45 ... Vertex of the cone, 46 ... Non-excision area, 47 ... excision area, 51 ... liver surface, 61 ... separation start position, 62 ... tumor projection image, 71 ... tumor center (or tumor center of gravity) projected on the liver surface, 72 ... separation start distance, 80 ... Main memory, 82 ... Central processing unit (CPU), 81 ... Magnetic disk, 83 ... Display memory, 84 ... Display, 85 ... Controller, 86 ... Mouse, 87 ... Keyboard, 88 ... Common bus

Claims (4)

A setting means for extracting a lesion in an organ using an image of a subject and setting a lesion area including at least the lesion;
Means for detecting travel information of a plurality of vessels outside the lesion area using the image of the subject;
Means for determining an ablation region up to the surface of the organ that includes the lesion region and does not include the plurality of vessels based on the lesion region and the running information of the plurality of vessels , the center of the lesion region Or means for expanding the area in a spherical shape until coming into contact with any of the plurality of vessels from the center of gravity toward the outside, and determining the area in contact with the expanded spherical area as an ablation area ;
Display means for displaying at least the resection area of the organ in an identifiable manner;
An organ excision region extraction / display apparatus comprising: 2. The organ excision region extraction / display apparatus according to claim 1, wherein the vessel is a vessel having a predetermined diameter or more. The means for determining the ablation region defines an approximately conical region having an angle formed by the direction vector of the vessel and is in contact with the spherical region, and from the defined approximately conical region to the apex of the approximately conical region and the spherical shape 3. The organ excision area extraction / display apparatus according to claim 1, wherein an area excluding an area surrounded by the area is determined as an excision area. The means for determining the ablation region is a substantially cone that is centered on a line segment connecting the lesion region and the center when the lesion region is projected onto the organ wall surface, has a predetermined angle as an apex angle, and is in contact with the spherical region The region is defined, and a region obtained by excluding the region surrounded by the apex of the substantially conical region and the spherical region from the defined substantially conical region is determined as an ablation region. The organ excision area extraction / display apparatus according to any one of the above.

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