JP4688361B2 - Organ specific area extraction display device and display method thereof - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a method and apparatus for extracting and displaying a specific area of an organ in a living body, and more particularly, to a simulation method and apparatus for assisting a doctor when a doctor diagnoses and treats an organ such as a liver in clinical practice. Is.
[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. Treatment includes catheterization in which a catheter is inserted into a subject and the affected part is excised, and surgical operation in which the affected part is excised by incision as usual. Among these, in a surgical operation, it is usually performed to obtain an image of an affected area by the medical image diagnostic apparatus and determine a part to be excised before the operation.
[0003]
A three-dimensional image is used as a display image for determining the part to be cut. This is because the resected portion can be determined intuitively because it is closer to the shape of the human body. On the other hand, with respect to extraction of organs on conventional images, methods for separating a target organ from other organs have been studied. As a method for extracting a specific region within a single organ, for example, There has been a method in which a doctor or the like sets a specific area by specifying a geometric plane or curved surface for specifying an area in a three-dimensional image based on anatomical knowledge.
[0004]
[Problems to be solved by the invention]
Although there is a method for extracting a specific region in a single organ as described above, in an actual clinical setting, an organ is not cut off with a geometric plane or curved surface as in simulation, Such a simulation was not very useful in an actual clinical setting.
[0005]
In addition, the excision area of an organ such as the liver must be set in consideration of the movement of various blood vessels such as veins and the position of the tumor, as well as the arteries that flow approximately in line with the portal vein. It was not considered.
[0006]
Further, in the operation, there has been a demand for preserving the function of the organ by excising only a blood vessel that nourishes the tumor of the organ such as the liver.
[0007]
An object of the present invention is to provide a method and an apparatus that can be displayed in an identifiable manner from a non-excised non-extracted region of an organ in which a plurality of types of blood vessels and the like have entered complicatedly.
[0008]
[Means for Solving the Problems]
The object is to extract a specific region of an organ using an image of a subject obtained by a medical diagnostic imaging apparatus and display the specific region on a display device, from information on a plurality of tissues constituting the target organ in the image, respectively. A step of setting a condition corresponding to the tissue, a step of extracting a region connected to the tissue information satisfying the condition as a resection candidate region, and the extracted resection candidate region can be distinguished from a non-extraction region of the target organ And a step of displaying. This is achieved by a method for extracting and displaying a specific region of an organ.
For example, when the target organ is the liver, the plurality of tissues here can selectively set a portal vein, a vein, a tumor, and the like.
[0009]
The display step is achieved by displaying the blood vessel or the center line of the blood vessel in a different form such as a color different from the surrounding blood vessel or the center line of the surrounding blood vessel or a blinking display.
[0010]
In the display step, the images obtained from the medical image diagnostic apparatus are three-dimensionally stacked to create a stacked three-dimensional image, and an arbitrary opacity is given to the threshold value and each pixel value to generate a three-dimensional image. This is achieved by displaying the extracted region of the organ in an identifiable manner with respect to the image created by the image reconstruction method that performs visualization.
[0011]
Further, in an apparatus for extracting a specific region of an organ using an image of a subject obtained by a medical image diagnostic apparatus and displaying the specific region, information on a plurality of tissues constituting a target organ in the image is displayed. Means for setting a condition corresponding to the tissue, means for extracting an area connected to the tissue information satisfying the condition as an excision candidate area, and displaying the extracted excision candidate area distinguishable from the non-extraction area of the target organ And means for extracting and displaying a specific region of an organ.
[0012]
In addition, the display of the extraction area and the non-extraction area is set to a display mode in which the non-extraction area is not displayed or a mode in which the extraction area is identified and displayed as a non-extraction area, and the display mode is switched according to the setting. As a result, when displaying as a non-extracted area, the positional relationship with the whole can be displayed, and when only the extracted area is displayed, only the extracted area can be displayed prominently, so that the diagnostic ability can be improved. .
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of a method and apparatus for extracting and displaying a specific region of an organ according to the present invention will be described below with reference to the accompanying drawings.
[0014]
As an embodiment, an X-ray CT image obtained by contrast imaging of the liver is used as a processing target image, and a procedure for specifying a liver region using portal travel information and a liver excision portion are displayed using the procedure. The method will be described below.
[0015]
As shown in FIG. 1A, a plurality of tomographic images 11 acquired by an image diagnostic apparatus capable of three-dimensional measurement, such as an X-ray CT apparatus and an MRI apparatus, are stacked to form 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 and a portal vein, and is displayed on a monitor, for example, as a pseudo three-dimensional image shaded and projected on a two-dimensional projection surface (not shown).
[0016]
FIG. 2 is a flowchart showing a method for extracting and displaying a specific region of an organ according to the present invention. The region specifying process 80 of the present invention includes a region of interest extracting process 81, a distance value converting process 82, a thinning process 83 or a surface pixel detecting process 84, a dominant area specifying process 85, a designated extracting process 86, and a cutting process 87.
[0017]
A region of interest extraction process 81 is performed on the read stacked three-dimensional image data, and a region of interest (target organ: liver parenchyma 31, portal vein 32) is extracted as shown in FIG. Here, for simplicity of explanation, only the portal vein 32 is extracted, but tumors and veins can be extracted similarly. As shown in FIG. 4, a distance value conversion process 82 is performed on the extracted portal vein 32, and a thinning process 83 or a surface pixel detection process 84 is further performed. The distance value conversion process 82 and the thinning process 83 or the surface pixel detection process 84 are performed by performing the thinning process first as indicated by the arrow, followed by the distance value conversion process, and the surface pixel detection process first. This may be followed by a distance value conversion process. Using the processing result, a dominant region specifying process 85 that is controlled by the portal vein 32 in the liver parenchyma 31 is performed. Also in this dominant area specifying process 85, areas of tumors and veins can be similarly specified. In other words, when the dominant region specifying process 85 is performed, not only the portal vein but also veins and tumors are obtained. If the portal vein corresponding to the dominant region of the tumor is obtained, the portal vein that nourishes the tumor is selected and resected. Therefore, the simulation takes into account the position of the tumor, and only the blood vessels that feed the tumor can be excised to a minimum to preserve the function of the organ.
[0018]
Next, a region-of-interest specifying process 86 for specifying and extracting a portal vein branch that specifies an ablation region in the portal vein 32 is performed, and an ablation process 87 for specifying an ablation region defined by the specified extraction process 86 is performed. .
[0019]
FIG. 5 is a flowchart showing an example of a detailed procedure in line with the implementation of the organ specific region extracting and displaying method of the present invention. First, the accumulated three-dimensional image data is read (step 21), and the region of interest (portal vein 32, liver substance 31) is extracted from the read three-dimensional image data as shown in FIG. 3 (step 22). In this extraction process, segmentation or region expansion using binarization using a known threshold value is used for the accumulated three-dimensional image data in the field of image processing.
[0020]
A distance value conversion process is performed on the extracted portal vein 32 (step 23). For the distance value conversion, a method of obtaining the shortest distance from the background pixel for each extracted pixel constituting the portal vein is used. As this known technique, “digital image processing for image understanding (II): Junichiro Toriwaki (Shokodo): 3.5 distance conversion and skeleton” can be cited. Three-dimensional distance value conversion is performed by extending this known technique in the three-dimensional direction. By combining the distance value conversion process of step 23 and the core line extraction result of step 24 and using the distance value at the position of the pixel constituting the core line, the blood vessel diameter of the extracted data (portal vein) can be defined.
[0021]
Further, a thinning process is performed on the extracted portal vein (step 24). For the core line extraction, the thinning process is performed on the extracted data, and the thinning result is used as the core line. The thinning method is a generally used two-dimensional thinning method, such as a method that extends the Hilditch algorithm to three dimensions, or a thinning method that extends three-dimensional thinning processing. Also good. Also here, as a known technique, “digital image processing for image understanding (II): by Junichiro Toriwaki (Shokodo): Algorithm 3.5” can be mentioned.
[0022]
Further, by using the distance value conversion result of step 23, the distance to the background pixel is 1 when the neighborhood is 8, 1 and √2 when the neighborhood is 18, and 1 and √2 and √3 when the neighborhood is 26, That is, by selecting a pixel adjacent to (in contact with) the background pixel, the surface extraction process can be performed in step 24.
[0023]
After performing such processing on the extracted portal vein, the control region specifying process controlled by the portal vein 32 of the liver parenchyma 31 is performed using the processing results of steps 23 and 24 (step 25). As a method of specifying the dominant region, a method of using the surface pixels of the portal vein 32, a method of using the core wire position of the portal vein 32, and using the core wire position and distance information (blood vessel diameter) of the portal vein 32 are used. A method etc. can be considered. In the method of using the blood vessel diameter, a method of simply using the blood vessel diameter, a method of using the blood vessel diameter to use the blood vessel cross-sectional area at the pixel point constituting the core line, and the number of pixels constituting the portal vein 32 (blood vessel volume) ) Can be considered. Here, a method in which the position of the core wire of the portal vein 32 and the blood vessel diameter are used together will be described. Further, not only the portal vein but also the tumor and vein can be similarly subjected to the dominant region specifying process.
[0024]
When the extracted liver substantial data set is defined as L = [Lijk], the extracted core data set of the portal vein 32 is defined as P = [Pijk], and the distance value conversion value (diameter) at Pijk is defined as Rijk, the liver substantial constituent pixels The core pixel Pijk that dominates Lijk can be defined as satisfying Equation 1.
Pijk = min (p, q, r) [(Lijk−Ppqr) ² / (α × Rpqr)] (1)
Here, α is a coefficient.
[0025]
That is, the core pixel Ppqr having the smallest relative value obtained by dividing the value based on the three-dimensional distance between the liver substantial constituent pixel Lijk and the core pixel Ppqr by the value proportional to the portal vein diameter Rpqr is the liver substantial constituent pixel Lijk. It is defined as a core line pixel Pijk that governs. In this case, the boundaries 54, 55, 56 of the dominant region of the liver parenchyma set for each core line of the portal branches 51, 52, 53 are the boundaries 55, 55, of the portal branch 52 having a larger blood vessel diameter, as shown in FIG. 56 is set at a distant position. In the above expression, the distance value conversion value (denominator in the above expression) can be calculated as an approximation from the diameter, and the edge length (circumference) or cross-sectional area of the blood vessel cross section can be given to obtain a conditional expression. .
[0026]
On the other hand, when a similar control region is set by using only the surface information of the portal vein branch or the position information of the core wire, assuming that the surface data set of the portal vein is S = [Sijk], the liver substantial constituent pixel Lijk is controlled. The portal surface pixel Sijk to be defined is defined as satisfying the following Expression 2.
Sijk = min (p, q, r) [(Lijk-Ppqr) ² ] (2)
[0027]
That is, in this case, the boundaries 64, 65, 66 of the dominant region of the liver parenchyma set for each of the portal branches 61, 62, 63 are the boundaries 64, 65, 66, regardless of the diameter of the portal branches as shown in FIG. 66 is set at an intermediate position between each portal branch. Pixel information Pijk (or Sijk) governing the liver substance determined in this way is provided for each liver substance pixel Lijk.
[0028]
Next, the control region of the tumor obtained by the control region specifying process among the set portal vein branches is displayed (step 26).
[0029]
Next, identification processing is performed on an extraction portal branch that identifies the ablation region, for example, a portion called a Gleason sheath (step 27). Set the portal branch used to determine the ablation area. The specification of Monmyakueda utilizing the aforementioned region growing method, a method of setting the portal vein branches from a specified position to the peripheral portion, three-dimensionally and take advantage of the processing of clipping such Monmyakueda Use a method to cut out
[0030]
Further, this processing is performed on all the portal vein branches, the entire extracted portal vein branches are grouped, and the total number of pixels constituting each portal vein branch group is obtained. By using this number of pixels as the denominator in Equation 1, it is possible to perform a dominant region setting process based on the volume of each portal branch. In this case, the process of step 26 needs to be performed before step 24.
[0031]
The ablation area data is specified (step 28). By searching for the core line pixel in the portal vein branch that is finally cut out, searching for and deleting the liver substantial pixel defined as being governed by this core line pixel, it is possible to set a desired excision region. That is, when the extracted core pixel data set is C = [Cijk], data including information on the set C in the set L is searched and deleted (not displayed as a calculation result) or replaced with distinguishable pixels and displayed. I do. The ablation area 71 as shown in FIG. 8 can be set by the above processing.
[0032]
FIG. 8 shows a case where the blood vessels 72 and 73 that dominate the excision region (region of interest) 71 are obtained from the preprocessing result. The blood vessels 72 and 73 are obtained only for the region of interest 71, and the region 74 inevitably has a minimum size for surrounding the region of interest 73 at a minimum. That is, the method shown in FIG. 8 is a direction in which the region of interest 71 approaches the blood vessels 72 and 73. In FIG. 8, there are two blood vessels involved in the region of interest 71. Actually, however, there are many three-dimensional blood vessels in the vicinity of the region of interest 71, so it is often difficult to specify the blood vessels. The two-dimensional approach shown can be easily identified.
[0033]
The data thus obtained is synthesized as display data, and display data processing is performed (step 29). For the image synthesis in step 28, a surface rendering method using a parallel projection method or a volume rendering method, which is a general image reconstruction method, is used.
[0034]
The processing result is displayed (step 30). At this time, it is preferable that the extracted specific region, that is, the ablation region and the other non-extraction region are displayed with different density values and hues so that the image observer can distinguish the specific region from the other non-extraction region. . Or it is good to display so that a specific area | region and other non-extraction area | region can be distinguished by blinking the ablation area | region. This completes the series of processing.
[0035]
FIG. 9 shows a configuration diagram of an example of hardware capable of realizing the system of the present invention. This system includes a CPU 92, a main memory 90, a magnetic disk 91, a display memory 93, a CRT 94, a controller 95, a mouse 96, and a common bus 97. Each tomographic image is stored in the magnetic disk 91, and the CPU 92 performs predetermined processing according to the projection display software (FIG. 5) in the main memory 90. In this processing, input / output processing and processing operations are performed using a keyboard attached to the mouse 96 and the controller 95. The stacked three-dimensional image is displayed on the CRT 94 via the display memory 93, and the processing shown in FIG. 5 is performed using the operation of the operator to obtain an image that meets the threshold condition. The display content is stored in the magnetic disk 91 and used for redisplay.
[0036]
Although the embodiment of the present invention has been described above, the method of the present invention is applicable not only to X-ray CT apparatuses but also to three-dimensional images acquired by other image diagnostic apparatuses such as a magnetic resonance imaging apparatus and an ultrasonic diagnostic apparatus. Can also be used. In addition to the liver described in the above embodiment, the target organ can be applied to many parts of the human body.
[0037]
According to the embodiment of the present invention, when an excision region and a non-excision region are displayed so as to be distinguishable, for example, when performing a liver excision simulation or the like, a surgical plan, an excision simulation, and an excision in a more clinical form. Rate calculation and three-dimensional visualization are possible.
[0038]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the method and apparatus which can be displayed distinguishably from the excision non-extraction area | region of the organ into which multiple types of blood vessel etc. entered complicatedly can be provided.
[Brief description of the drawings]
FIG. 1 is a diagram showing a relationship between a tomogram and data.
FIG. 2 is a flowchart illustrating an outline of a processing method according to the present invention.
FIG. 3 is a diagram showing extraction of a region of interest from tomographic image data.
FIG. 4 is a diagram showing various processes for extracted data.
FIG. 5 is a diagram for explaining an example of a basic processing flow of the present algorithm.
FIG. 6 is a diagram showing a positional relationship between region boundaries when region setting is performed using a combination of the extracted blood vessel distance value conversion processing and the thinning result according to the present invention.
FIG. 7 is a diagram showing the positional relationship between region boundaries when region setting is performed using only the thinning result of extracted blood vessels or surface information in the present invention.
FIG. 8 is a diagram showing a result of setting a resection area according to the present invention.
FIG. 9 is a diagram showing an example of a hardware configuration capable of implementing the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Tomographic image, 12 ... Stacked three-dimensional image, 31, 32 ... Extraction data, 51, 52, 53 ... Extraction blood vessel, 54, 55, 56 ... Control region boundary, 61, 62, 63 ... Extraction blood vessel, 64, 65 , 66 ... dominant region boundary, 71 ... ablation

Claims (3)

Means for reading an image obtained by imaging a target organ of a subject obtained by a medical image diagnostic apparatus ;
Setting of a condition for extracting a region where the blood vessel of the subject included in the image is imaged, and a condition for extracting a region where the tumor of the subject included in the image is captured Means for accepting ,
The first region in the image is extracted according to the condition for extracting the region in which the blood vessel of the subject included in the image is captured, and the tumor of the subject included in the image is captured Means for extracting a second region in the image according to a condition for extracting the region ;
A dominating region specifying means for specifying a region connected to the extracted first region as a dominating region;
Display means for displaying the first area and the second area;
A designation means for accepting designation of an arbitrary position on the displayed first area;
Means for displaying the dominant region from the arbitrary position to the peripheral part so as to be distinguishable from other regions of the target organ;
An apparatus for extracting and displaying a specific area of an organ . The dominant region specifying means specifies the dominant region based on a distance from a blood vessel corresponding to the extracted first region or a blood vessel diameter of a blood vessel corresponding to the extracted first region.
The organ specific region extracting and displaying device according to claim 1.   A display method in an organ specific area extraction / display apparatus that extracts and displays a specific area of an organ using an image obtained by imaging a target organ of a subject obtained by a medical image diagnostic apparatus,
The specific area extraction display device reads an image of the subject;
The specific region extraction / display apparatus extracts a condition for extracting a region where the blood vessel of the subject included in the image is captured, and a region where the tumor of the subject included in the image is captured. A step for accepting the setting for the condition for
The specific area extraction and display device extracts a first area from the image according to a condition for extracting an area where the blood vessel of the subject is imaged, and a tumor of the subject included in the image Extracting a second region from the image according to a condition for extracting a photographed region;
The specific area extraction and display device specifies an area connected to the first area as a dominant area;
The specific area extraction display device displaying the first area and the second area;
The specific area extraction display device accepts designation of an arbitrary position on the displayed first area;
The specific region extraction and display device displays the dominant region from the arbitrary position to the peripheral part so as to be distinguishable from other regions of the target organ;
A display method for an organ specific region extraction / display apparatus characterized by comprising:

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