Three-dimensional model construction method for hollow organs, model, electronic device and storage medium

Abstract

The present invention discloses a method for constructing a three-dimensional model of a hollow organ, a model, an electronic device, and a storage medium. The contour of the target hollow organ in the enlarged state is determined by obtaining a two-dimensional plan view through digestive endoscopy examination, and an orthogonal projection view is obtained by three-dimensional modeling of CT images. The contour of the target hollow organ in the non-enlarged state is obtained by combining the contour of the target hollow organ in the enlarged state. The enlargement coefficient is obtained through perimeter calculation, and the hollow organ in the non-enlarged state is enlarged according to the enlargement coefficient to obtain a three-dimensional model of the enlarged target hollow organ; both the digestive endoscopy image and the CT image are the original examination habits and techniques, and the enlargement of the gastric cavity after inflation can be understood without deviating from the original examination habits and techniques, and the perception of the relationship between the gastric cavity and adjacent tissues can be restored.

Description

Technical Field

[0001] The present invention relates to the technical field of the construction of enlarged models of hollow organs, and specifically, to a method for constructing a three-dimensional model of a hollow organ, a model, an electronic device, and a storage medium. Background Art

[0002] In the related art, an endoscope can only visually observe the situation inside the digestive tract lumen, and cannot obtain the external field of view at the corresponding moment, nor can it simultaneously take CT images during use; CT images can show three-dimensional images, but when taking CT images, the patient is usually in a natural state, that is, when the gastric cavity is not inflated or filled with water. When performing an endoscopic examination, the gastric cavity needs to be continuously inflated to stretch the mucosa to obtain the best observation field of view. This results in the inflated gastric cavity having a closer relationship with the surrounding adjacent tissues due to expansion, while the previously taken CT images do not consider this factor, thus affecting the doctor's endoscopic diagnosis and treatment.

[0003] Therefore, when the inflated situation of hollow organs such as the gastric cavity and the surrounding adjacent tissues being compressed cannot be seen, correct information cannot be provided to guide the doctor's understanding of the real situation. Summary of the Invention

[0004] The purpose of the present invention is to solve the above problems, and provide a method for constructing a three-dimensional model of an enlarged hollow organ, a model, an electronic device, and a storage medium, so as to solve the problem that when the enlarged situation of hollow organs such as the gastric cavity and the surrounding adjacent tissues being compressed cannot be seen, correct information cannot be obtained, thereby guiding the doctor's understanding of the real situation.

[0005] To solve the above problems, the present invention provides the following technical solutions:

[0006] On the one hand, a method for constructing a three-dimensional model of an enlarged hollow organ includes

[0007] Determine its contour according to the two-dimensional plane diagram of the target hollow organ in the enlarged state;

[0008] Construct a three-dimensional model according to the image of the target hollow organ in the non-enlarged state, and determine the orthographic projection diagram of the target hollow organ in the non-enlarged state according to the three-dimensional model;

[0009] Determine all the contour points of the target hollow organ in the enlarged and non-enlarged states according to the two-dimensional plane diagram and the orthographic projection diagram; determine the contour diagrams of the target hollow organ in the enlarged and non-enlarged states according to the angles between the contour points and the coordinate origin;

[0010] Calculate the perimeters of the target hollow organ in the enlarged state and the target hollow organ in the non-enlarged state respectively, and calculate the enlargement coefficient according to the perimeters of the two;

[0011] The enlarged three-dimensional model of the target hollow organ is obtained according to the enlargement coefficient and the three-dimensional model in the non-enlarged state.

[0012] In a related embodiment, determining the orthogonal projection image of the target hollow organ in the unenlarged state based on the three-dimensional model includes:

[0013] When loading the three-dimensional model, the y coordinate of each point is ignored, and the x and z axis coordinate values are obtained. A plan view of the target hollow organ is drawn according to the x and z values of each point to obtain the orthogonal projection of the three-dimensional model on the XZ axis.

[0014] In a related embodiment, determining all contour points of the target hollow organ in the expanded and unexpanded states based on the two-dimensional plan view and the orthogonal projection view includes:

[0015] From the top to the bottom of the two-dimensional plane image and the orthogonal projection image, draw a straight line parallel to the x-axis at a set distance along the z-axis direction. This straight line will pass through the orthogonal projection and the two-dimensional plane image respectively, and produce two intersection points with them. These two intersection points are the points with the minimum and maximum x values. Draw lines and points in sequence to obtain all the contour points of the target hollow organ in both expanded and non-expanded states.

[0016] In a related embodiment, determining the contour images of the target hollow organ in the expanded and non-expanded states based on the angle between the contour point and the coordinate origin includes:

[0017] Calculate the angle between the line connecting the contour point and the origin of the coordinate system and the x or z axis. Similarly, calculate the angles of all contour points and sort them in ascending order to obtain the contour points in a clockwise direction.

[0018] In a related embodiment, the perimeter of the target hollow organ in the non-enlarged state is calculated as the sum of the Euclidean distances between all two adjacent contour points in the contour image of the target hollow organ in the non-enlarged state.

[0019] In a related embodiment, calculating the perimeter of the target hollow organ in the expanded state includes:

[0020] The ratio of the length of a real object in a two-dimensional plane image to the distance between pixels at the same position in the two-dimensional plane image corresponding to the length of the real object is a relationship coefficient;

[0021] According to the contour of the target hollow organ in the expanded state, the sum of the Euclidean distances between all two adjacent contour points is calculated as the pixel perimeter;

[0022] The perimeter of the target hollow organ in the expanded state is the product of the pixel perimeter and the relationship coefficient.

[0023] In related embodiments, obtaining the three-dimensional model of the target hollow organ after expansion based on the expansion coefficient and the three-dimensional model in the unexpanded state includes:

[0024] Enlarge the three-dimensional model by the expansion coefficient by defining the scaling ratio through an instruction;

[0025] Translate the coordinates of each vertex of the mesh of the enlarged three-dimensional model relative to the centroid so that the centroid moves to the origin of coordinates;

[0026] Scale each vertex of the enlarged three-dimensional model;

[0027] Move the enlarged mesh back to the original centroid position;

[0028] Update the vertices of the mesh of the enlarged three-dimensional model.

[0029] In a second aspect, an enlarged three-dimensional model of a hollow organ is a model constructed based on a method for constructing an enlarged three-dimensional model of a hollow organ.

[0030] In a third aspect, an electronic device includes a memory and a processor. Computer-readable instructions are stored in the memory. When the computer-readable instructions are executed by the processor, the processor executes a method for constructing an enlarged three-dimensional model of a hollow organ.

[0031] In a fourth aspect, a computer-readable storage medium stores a computer program. When the computer program runs on a computer, the computer executes a method for constructing an enlarged three-dimensional model of a hollow organ.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention uses a digestive endoscopy examination to obtain a two-dimensional plan view to determine the contour of the target hollow organ in the expanded state, uses CT image three-dimensional modeling to obtain an orthogonal projection view, combines the contour of the target hollow organ in the expanded state to obtain the contour maps of the target hollow organ in both the expanded and unexpanded states, calculates the expansion coefficient through the perimeter ratio of the two, and expands the hollow organ in the unexpanded state by this expansion coefficient to obtain an enlarged three-dimensional model of the target hollow organ; both the digestive endoscopy image and the CT image are the original examination habits and techniques, and the expansion of the gastric cavity after inflation can be understood without departing from the original examination habits and techniques, and the perception of the relationship between the gastric cavity and adjacent tissues can be restored. Description of the Drawings

[0034] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings, where:

[0035] Figure 1 It is a plan view of the inflated gastric cavity during X-ray imaging in ERCP.

[0036] Figure 2 It is an orthographic projection view of the non-inflated gastric cavity based on the three-dimensional reconstruction model.

[0037] Figure 3 It is to extract the complete contour points of the inflated gastric cavity (large) and the non-inflated gastric cavity (small).

[0038] Figure 4 It is to measure the pixel diameter of the endoscopic lumen.

[0039] Figure 5 It is a comparison diagram of the three-dimensional reconstruction model (non-inflated gastric cavity) before and after being enlarged by a coefficient.

[0040] Figure 6 It is a flowchart of the method for constructing a three-dimensional model of an enlarged hollow organ. Specific Embodiments

[0041] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will further describe the present invention in detail in conjunction with Figures 1 to 6 A further detailed description of the present invention is made. The described embodiments should not be regarded as limitations on the present invention. All other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0042] This embodiment is used to solve the problems in upper gastrointestinal endoscopy diagnosis and treatment, such as the gastric cavity expanding due to inflation during endoscopy, which changes the anatomical relationship with adjacent tissues, thus affecting the doctor's surgical judgment and operation risk. A method for constructing a three-dimensional model of an enlarged hollow organ is proposed; as Figure 6 shown, the specific steps are as follows:

[0043] Considering that currently, endoscopic retrograde cholangiopancreatography (ERCP) also performs relevant operations through the oral cavity via the endoscope and finally reaches the duodenum through the gastric cavity. At the same time, X-ray fluoroscopy images are taken for observation. With the help of this surgery and related equipment, when passing through the gastric cavity, conventional gastroscopy is simulated to inflate the gastric cavity, and the X-ray camera is adjusted to take pictures of the complete contour of the inflated gastric cavity, which is recorded as the post-inflation picture, as Figure 1 shown;

[0044] 2) Using the CT imaging data of the same patient, the three-dimensional reconstruction of the patient's thoracic and abdominal organs is carried out with the help of the totalsegmentator software, and the part of the gastric cavity is separately extracted;

[0045] 3) Using the existing open3d library, each point in the three-dimensional model is loaded, the y coordinate of each point is ignored, and the x and z axis coordinate values are obtained. Then, using the matplotlib library, a planar graph of the stomach is drawn according to the x and z values of each point to obtain the orthogonal projection of the three-dimensional model on the XZ axis, and a two-dimensional planar graph with the same viewing angle as the gastric cavity picture taken by ERCP is obtained, which is recorded as the non-inflated picture, as Figure 2 shown; Since the reconstructed three-dimensional model may be tilted or upside down, obtaining its coordinate values in the vertical and horizontal directions (Z axis and X axis) helps to ensure that the placement position of the three-dimensional model is consistent with the vertical direction of the human body, and the extracted coordinate information is helpful for the progress of the following steps.

[0046] 4) Use the PAIR software to outline the entire contour of the gastric cavity in the X-ray image taken during ERCP and save it as a TAR compressed file containing coordinate information; decompress the compressed package to obtain a pose.json file, which contains the pixel coordinates of each contour point.

[0047] 5) Obtain all the contour points of the gastric cavity in the two pictures: It can be imagined that the projection is a plane composed of many points. Therefore, from the top to the bottom of the two images, a straight line parallel to the x-axis is drawn every 1 mm along the z-axis direction. This straight line will pass through the planar graph of the projection and generate two intersection points with it. These two intersection points are the points with the minimum and maximum x values. Draw lines and take points in sequence until the bottom of the image to obtain all the contour points of the entire gastric cavity; if the contour points of a single picture are directly extracted, all the extracted points have no coordinate information and are a mess of scattered points. Moreover, there are many points on a single picture, and it is not certain whether all the extracted points are contour points. Drawing lines and taking points in sequence can ensure that the extracted points are all contour points and have coordinate information such as (1, y), (2, y).

[0048] 6) Sort the extracted contour points in a clockwise direction: Since the contour points are not extracted step by step in a clockwise or counterclockwise direction when extracting them, the perimeter cannot be calculated. Therefore, the contour points must be sorted in a clockwise or counterclockwise direction first. The specific method is as follows: Use the to calculate the angle between each point and the origin of coordinates through the x and z axis coordinates of two points. By analogy, calculate the angle sizes of all contour points and sort them in ascending order to obtain the ordered contour points in the clockwise direction, as shown in Figure 3 ; After drawing lines and taking points, a bunch of points with coordinate information (1, y), (2, y), (2, y1), (3, y2) will be obtained. The computer needs a rule to process these points. This rule is to calculate the angle sizes and arrange them in sequence, which is the contour of the image.

[0049] 7) Calculate the perimeter of the gastric cavity contour:

[0050] ① Calculate the perimeter of the gastric cavity in the non-inflated picture: Calculate the Euclidean distance between every two points among all contour points, and add up the distances between all points to obtain the approximate perimeter of the entire contour. The specific calculation method is as follows:

[0051] The coordinates of the ordered point 1 are: ;

[0052] The coordinates of the ordered point 2 are: ;

[0053] The Euclidean distance between the two is:

[0054] ② Calculate the perimeter of the gastric cavity in the inflated picture: It should be noted that for the gastric model reconstructed in three dimensions based on CT images, the orthogonal projection extracted, that is, the contour point coordinates of the non-inflated picture, are actual coordinates, while the gastric cavity plan view outlined by the PAIR software, that is, the picture after inflation, is an X-ray image. The output is the pixel coordinates of the contour rather than the actual coordinates of the inflated gastric cavity. Therefore, the sum of the Euclidean distances calculated through the pixel coordinates is not the actual perimeter of the inflated gastric cavity, and the two need to be converted. The specific method is as follows:

[0055] a: First, calculate the relationship between the pixel distance and the actual distance of the gastric cavity contour extracted from the inflated picture: It is known that the true diameter of the endoscope used during the ERCP operation is 13.5 mm, and the resolution of the X-ray image after inflation is 2840 * 2874. Load this picture into the computer paint software and use the drawing tool to draw a line segment perpendicular to the endoscope tube body (i.e., measure the diameter, as shown in Figure 4),(pixel coordinates at both ends of the endoscopic lumen diameter can be obtained. Subsequently, the pixel distance between two pixels is calculated. By the ratio of the true diameter of the endoscopic lumen to the pixel diameter on the image: actual physical distance / pixel distance = relationship coefficient R.)

[0056] b: Calculate the perimeter of the inflated gastric contour: Calculate the Euclidean distance between each pair of points among all the contour points, and sum up the distances between all points to obtain the approximate perimeter of the entire contour. The specific calculation method is the same as that for the non-inflated contour diagram, but note that the perimeter obtained at this time is the pixel distance.)

[0057] c: Multiply the relationship coefficient R on this pixel distance to obtain the actual perimeter of the inflated gastric lumen: For example, if the actual distance of one pixel is 0.147 mm and the calculated perimeter is 5238.252 pixels, its actual perimeter is: 5238.252 * 0.147 = 770.023 mm.)

[0058] 8) Calculate the gastric lumen expansion coefficients of the two pictures before and after inflation according to the perimeter: For example, if the perimeter of the non-inflated gastric lumen is 582.687 mm and the perimeter of the inflated gastric lumen is 770.023 mm, the calculated expansion coefficient is 770.023 mm / 582.687 mm = 1.321)

[0059] 9) Scale up the reconstructed three-dimensional gastric lumen model according to this ratio. As Figure 5 shown, so as to guide the doctor to correctly perceive the anatomical relationship of the tissues adjacent to the inflated gastric lumen with the help of this correction model to assist in relevant diagnosis and operations. The specific operations are as follows:

[0060] Define the scaling ratio through instructions (scale_factor = 1.321 # Scale up the non-inflated three-dimensional model reconstructed based on CT images by 1.321 times)

[0061] Translate the coordinates of each vertex of the mesh relative to the centroid so that the centroid moves to the coordinate origin (vertices_centered = vertices – centroid)

[0062] Scale each vertex

[0063] (scaled_vertices = vertices_centered * scale_factor)

[0064] Move the enlarged mesh back to the original centroid position (scaled_vertices += centroid)

[0065] Update the vertices of the mesh

[0066] (mesh.vertices = o3d.utility.Vector3dVector(scaled_vertices))

[0067] Through testing and verification of a considerable number of images, a general expansion coefficient of the gastric cavity after inflation can be obtained to fill the current knowledge gap in this area. The calculation method of this gastric cavity expansion coefficient can be referred to for solving the clinical impact caused by deformation of other hollow organs such as the bladder and uterus.

[0068] An electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor; when the processor executes the computer program, it implements the steps of a method for constructing a three-dimensional model of an expanded hollow organ.

[0069] The electronic device can be a desktop computer, a notebook, a handheld computer, a cloud server, and other electronic devices. The electronic device can include, but is not limited to, a processor and a memory. Those skilled in the art can understand that the figure is only an example of the electronic device and does not constitute a limitation on the electronic device. It can include more or fewer components than shown in the figure, or different components.

[0070] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0071] The memory can be an internal storage unit of the electronic device, for example, the hard disk or memory of the electronic device. The memory can also be an external storage device of the electronic device, for example, a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) card, a Flash Card, etc. equipped on the electronic device. The memory can also include both the internal storage unit and the external storage device of the electronic device. The memory is used to store the computer program and other programs and data required by the electronic device.

[0072] In several embodiments provided by this application, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device embodiments described above are merely illustrative. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architectures, functions, and operations of devices, methods, and computer program products according to multiple embodiments of the present invention. In this regard, each block in the flowchart or block diagram can represent a module, a program segment, or a part of code, and the module, program segment, or part of code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than that marked in the accompanying drawings. For example, two consecutive blocks can actually be executed substantially in parallel, and they can sometimes be executed in the reverse order, depending on the functions involved. It should also be noted that each block in the block diagram and / or flowchart, as well as the combination of blocks in the block diagram and / or flowchart, can be implemented by a dedicated hardware-based system for performing the specified functions or actions, or can be implemented by a combination of dedicated hardware and computer instructions.

[0073] In addition, the functional modules in various embodiments of the present invention can be integrated together to form an independent part, or each module can exist alone, or two or more modules can be integrated to form an independent part.

[0074] If the above functions are implemented in the form of software functional modules and sold or used as an independent product, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of the present invention. It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including", or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article, or device including a series of elements not only includes those elements but also includes other elements not explicitly listed, or further includes elements inherent to such process, method, article, or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article, or device including the said element.

[0075] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention. It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0076] As described above, these are only the specific implementation manners of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or replacements, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for constructing a three-dimensional model of an enlarged hollow organ, characterized in that, including Determine the contour of the target hollow organ according to the two-dimensional plan view of the target hollow organ in the enlarged state; Construct a three-dimensional model based on the image of the target hollow organ in the non-enlarged state, and determine the orthogonal projection of the target hollow organ in the non-enlarged state according to the three-dimensional model; Determine all the contour points of the target hollow organ in the enlarged and non-enlarged states according to the two-dimensional plan view and the orthogonal projection; Determine the contour maps of the target hollow organs in the enlarged and non-enlarged states according to the angles between the contour points and the coordinate origin; Calculate the perimeters of the target hollow organ in the enlarged state and the target hollow organ in the non-enlarged state respectively, and calculate the enlargement coefficient according to the perimeters of the two; The perimeter of the target hollow organ in the enlarged state is determined according to the relationship coefficient, and the relationship coefficient is the ratio of the length of the real object existing in the two-dimensional plan view to the pixel distance at the same position corresponding to the length of the real object in the two-dimensional plan view; Obtain the three-dimensional model of the enlarged target hollow organ according to the enlargement coefficient and the three-dimensional model in the non-enlarged state.

2. The method for constructing a three-dimensional model of an enlarged hollow organ according to claim 1, wherein Determining the orthogonal projection of the target hollow organ in the non-enlarged state according to the three-dimensional model includes: Load the three-dimensional model, ignore the y coordinate of each point, obtain the values of its x and z axis coordinates, and draw a plan view of the target hollow organ according to the values of each point's x and z to obtain the orthogonal projection of the three-dimensional model on the XZ axis.

3. The method for constructing an enlarged three-dimensional model of a hollow organ according to claim 1, characterized in that, Determining all the contour points of the target hollow organ in the enlarged and non-enlarged states according to the two-dimensional plan view and the orthogonal projection includes: Draw a straight line parallel to the x-axis at a set distance along the z-axis direction from the top to the bottom of the two figures of the two-dimensional plan view and the orthogonal projection respectively. This straight line will pass through the orthogonal projection and the two-dimensional plan view respectively and generate two intersection points with them. These two intersection points are the points with the smallest and largest x values. Draw lines and take points in turn until all the contour points of the target hollow organs in the enlarged and non-enlarged states are obtained.

4. The method for constructing a three-dimensional model of an enlarged hollow organ according to claim 1, wherein Determining the contour maps of the target hollow organs in the enlarged and non-enlarged states according to the angles between the contour points and the coordinate origin includes: Calculate the angle between the line connecting the contour point and the coordinate origin and the x or z axis, and calculate the angle sizes of all the contour points in turn, and sort them in ascending order to obtain the ordered contour points in the clockwise direction.

5. The method for constructing a three-dimensional model of an enlarged hollow organ according to claim 1, wherein Calculate the perimeter of the target hollow organ in the non-enlarged state as the sum of the Euclidean distances between all adjacent two contour points in the contour map of the target hollow organ in the non-enlarged state.

6. The method for constructing a three-dimensional model of an enlarged hollow organ according to claim 1, wherein Calculating the perimeter of the target hollow organ in the enlarged state includes: Calculate the sum of the Euclidean distances between all adjacent two contour points according to the contour of the target hollow organ in the enlarged state as the pixel perimeter; The perimeter of the target hollow organ in the enlarged state is the product of the pixel perimeter and the relationship coefficient.

7. The method for constructing a three-dimensional model of an enlarged hollow organ according to claim 1, wherein Obtaining the three-dimensional model of the enlarged target hollow organ according to the enlargement coefficient and the three-dimensional model in the non-enlarged state includes: Define the scaling ratio through instructions to enlarge the three-dimensional model according to the enlargement coefficient; Translate the coordinates of each vertex of the enlarged three-dimensional model grid relative to the centroid so that the centroid moves to the coordinate origin; Scale each vertex of the enlarged three-dimensional model; Move the enlarged grid back to the original centroid position; Update the vertices of the enlarged three-dimensional model grid.

8. An enlarged three-dimensional model of a hollow organ, characterized in that, A model constructed by the method for constructing a three-dimensional model of an enlarged hollow organ according to any one of claims 1-7.

9. An electronic device, comprising a memory and a processor, wherein computer-readable instructions are stored in the memory, and when the computer-readable instructions are executed by the processor, it is characterized in that The processor is caused to execute the method for constructing a three-dimensional model of an enlarged hollow organ according to any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, A computer program is stored in the readable storage medium, and when the computer program runs on a computer, the computer is caused to execute the method for constructing a three-dimensional model of an enlarged hollow organ according to any one of claims 1-7.

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