Medical image processing device, method, and program

Abstract

To correct a core line near a branch part of a tubular structure.SOLUTION: A medical image processing device includes an extraction unit and a correction unit. The extraction unit extracts a lumen region which is the internal region of a tubular structure from medical image data including the tubular structure having a branch part within the body, and performs a thinning process on the lumen region to extract a first core line. The correction unit generates a second core line by correcting the position of the branch point in the first core line on the basis of the information on the lumen region and the information on the first core line.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The embodiments disclosed in this specification and the drawings relate to a medical image processing apparatus, method, and program.

Background Art

[0002] Conventionally, a technique of performing thinning processing on a roughly extracted blood vessel region to extract a center line of the blood vessel region has been known. In this thinning processing, at the vicinity of a branch portion of a blood vessel, the center line is extracted so as to pass through the center between two branching blood vessels. When the center line is extracted in this way, at the vicinity of the branch portion, the center line of one of the branching blood vessels is attracted to the center line of the other branching blood vessel. Therefore, in a stretched image centered on the center lines of the branching blood vessels and a multi-cross-sectional image orthogonal to the center lines of the branching blood vessels, a bulge of a blood vessel different from the actual shape of the blood vessel may occur. This is due to the distortion of the center line in the vicinity of the branch portion of the blood vessel. Further, this is applicable not only to blood vessels but also to tubular structures including branch portions such as bronchi.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to correct the center line in the vicinity of the branch portion of a tubular structure. However, the problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above problems. The problems corresponding to the respective effects of the respective configurations shown in the embodiments described later can also be regarded as other problems.

Means for Solving the Problems

[0005] The medical image processing apparatus according to the embodiment includes an extraction unit and a correction unit. The extraction unit extracts a lumen region, which is an internal region of a tubular structure, from medical image data including the tubular structure having a branch portion in a living body, and extracts a first core line by performing a thinning process on the lumen region. The correction unit generates a second core line in which the position of a branch point in the first core line is corrected based on the information of the lumen region and the information of the first core line.

Brief Description of the Drawings

[0006]

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DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, embodiments of a medical image processing apparatus will be described in detail with reference to the drawings. In the following embodiments, as a specific example, it is assumed that a blood vessel (branch blood vessel) having a branch portion in a living body is analyzed. Such a blood vessel having a branch portion exists, for example, in the coronary artery (coronary artery) of the heart.

[0008] First, the above-described conventional core line extraction will be specifically described. Hereinafter, with respect to the core line extracted by the thinning process, a stretched image centered on the core line of the branching blood vessel and a multi-sectional image orthogonal to the core line of the branching blood vessel will be described with reference to FIGS. 76 and 77, respectively.

[0009] FIG. 76 is a diagram for explaining a stretched image centered on a core line extracted by a conventional thinning process. FIG. 76 shows a cross-section 10 of a lumen region extracted from medical image data and a stretched image 20. The cross-section 10 is an arbitrary cross-section in three-dimensional medical image data. Further, in the cross-section 10, a core line 11 projected from a direction perpendicular to the cross-section is shown. The stretched image 20 is an image obtained by deforming the cross-section 10 such that the core line 11 branching to the left becomes a straight line.

[0010] Focusing on the core line 11 branching to the left and the boundary line 12 located on the left in the cross-section 10, the distance d2 between the core line 11 and the boundary line 12 at the branch point is larger than the distance d1 between the core line 11 before branching and the boundary line 12 and the distance d3 between the core line 11 after branching and the boundary line 12. When a stretching process centered on the core line 11 branching to the left is performed on this cross-section 10, an unnatural bulge occurs in the vicinity of the branch point where the distance d2 is shown, as in the stretched image 20. In fact, since there is no bulge in the vicinity of the branch point of the boundary line 12, it may cause inconvenience in diagnosis and analysis.

[0011] FIG. 77 is a diagram for explaining multi-sectional images orthogonal to a core wire extracted by a conventional thinning process. In FIG. 77, a lumen region 30 extracted from medical image data and three cross-sectional images 41, 42, 43 are shown. In the lumen region 30, a core wire 31, a cross-section 32 of a blood vessel before branching, a cross-section 33 of a blood vessel at a branch point, and a cross-section 34 of a blood vessel after branching are shown. The three cross-sectional images 41, 42, 43 are images corresponding to the cross-sections 32, 33, and 34 of the lumen region 30, respectively.

[0012] In FIG. 77, the three cross-sectional images 41, 42, 43 are shown in the order of each position along the traveling direction of the blood vessel (each position from the upstream to the downstream of the blood vessel). With respect to the distance d1 between the center of the blood vessel and the left wall surface of the cross-sectional image 41 at the position p1 and the distance d3 between the center of the blood vessel and the left wall surface of the cross-sectional image 43 at the position p3, the distance d2 between the center of the blood vessel and the left wall surface of the cross-sectional image 42 at the position p2 is larger. In the multi-sectional image of the blood vessel, since the cross-sections may be sequentially displayed in the traveling direction of the blood vessel with the core wire 31 as the center, when the user checks this, the blood vessel may appear to bulge at the position p2 near the branch point. This may cause inconvenience in diagnosis and analysis as described above.

[0013] Also, when generating a multi-sectional image, the direction of the core wire extracted by the conventional thinning process changes abruptly at the branch point. If the branch point is a corner point, since a tangent cannot be defined, there is a risk that the orthogonal cross-section is not uniquely determined, or the multi-sectional image changes greatly near the branch point.

[0014] As described above, it can be said that the core wire extracted by the conventional thinning process is distorted at the branch point. Such distortion of the core wire may cause inconvenience in diagnosis and analysis. In the following embodiments, correction of the distortion of the core wire will be described.

[0015] (First Embodiment) FIG. 1 is a block diagram showing a configuration example of a medical image processing apparatus 100 according to a first embodiment. The medical image processing apparatus 100 includes a processing circuit 110, a memory 120, a display 130, an input interface 140, and a communication interface 150. Data communication between the processing circuit 110, the memory 120, the display 130, the input interface 140, and the communication interface 150 is performed via a bus (BUS).

[0016] Hereinafter, the memory 120, the display 130, the input interface 140, and the communication interface 150 will be described first, and then the processing circuit 110 will be described.

[0017] The memory 120 is a storage device such as an HDD (Hard Disk Drive), an SSD (Solid State Drive), or an integrated circuit memory device that stores various information. The memory 120 stores, for example, medical image data such as imaging data and reconstructed image data. The medical image data is, for example, three-dimensional volume data (three-dimensional volume data) captured by an X-ray computed tomography apparatus (X-ray CT apparatus). In addition to an HDD or an SSD, the memory 120 may be a drive device that reads and writes various information to and from a portable storage medium such as a CD (Compact Disc), a DVD (Digital Versatile Disc), a flash memory, or a semiconductor memory element such as a RAM (Random Access Memory). Further, the storage area of the memory 120 may be in an external storage device connected via a network. For example, the memory 120 stores display image data. The memory 120 stores a processing program for medical image processing in the present embodiment.

[0018] The display 130 displays various types of information. For example, the display 130 outputs (displays) a display image generated by the processing circuit 110, a GUI (Graphical User Interface) for receiving various operations from the operator, and the like. For example, as the display 130, for example, a liquid crystal display (LCD), a CRT (Cathode Ray Tube) display, an organic EL display (OELD), a plasma display, or any other display can be used as appropriate.

[0019] The input interface 140 receives various input operations from the operator, converts the received input operations into electrical signals, and outputs them to the processing circuit 110. For example, the input interface 140 receives from the operator image processing conditions when generating a processed image and the like.

[0020] As the input interface 140, for example, a mouse, a keyboard, a trackball, a switch, a button, a joystick, a touch pad, and a touch panel display can be used as appropriate.

[0021] Note that in this embodiment, the input interface 140 is not limited to those equipped with physical operation components such as a mouse, a keyboard, a trackball, a switch, a button, a joystick, a touch pad, and a touch panel display. For example, a processing circuit for receiving an electrical signal corresponding to an input operation from an external input device provided separately from the apparatus and outputting this electrical signal to the processing circuit 110 is also included in the examples of the input interface 140.

[0022] The communication interface 150 is a circuit for communicating with an external device by wire, wirelessly, or both. The external device may be, for example, a server included in systems such as modalities, medical information processing devices, radiological information systems (RIS), hospital information systems (HIS), and picture archiving and communication systems (PACS), or other workstations, etc.

[0023] The processing circuit 110 controls the operation of the entire medical image processing apparatus 100 in response to the electrical signals of the input operations output from the input interface 140. For example, as hardware resources, the processing circuit 110 has processors such as a CPU, an MPU (Micro Processing Unit), and a GPU (Graphics Processing Unit), and memories such as a ROM and a RAM.

[0024] Specifically, the processing circuit 110 has a system control function 111, an acquisition function 112, an extraction function 113 (extraction unit), a correction function 114 (correction unit), and a display control function 115 (display control unit). The processing circuit 110 executes the system control function 111, the acquisition function 112, the extraction function 113, the correction function 114, and the display control function 115 by a processor that executes a program developed in the memory. Note that these functions are not limited to being realized by a single processing circuit. It is also possible to configure a processing circuit by combining a plurality of independent processors, and each function is realized by each processor executing a program.

[0025] The system control function 111 is a function that controls the medical image processing apparatus 100 based on an input operation received from an operator via the input interface 140. Specifically, the processing circuit 110 reads out a processing program stored in the memory 120 by the system control function 111 and expands it onto the memory in the processing circuit 110, and controls each part of the medical image processing apparatus 100 according to the expanded processing program. For example, the processing circuit 110 controls each function of the processing circuit 110 based on an input operation received from an operator via the input interface 140.

[0026] The acquisition function 112 is a function that acquires medical image data. Specifically, the processing circuit 110 acquires medical image data stored in the memory 120 or medical image data via the network NW by the acquisition function 112. Note that the acquisition function 112 is an example of an acquisition unit.

[0027] The extraction function 113 is a function that extracts a lumen region and a centerline from medical image data. Specifically, the processing circuit 110 extracts a lumen region, which is an internal region of a tubular structure, from medical image data including a tubular structure having a branch portion in a living body by the extraction function 113. Then, the processing circuit 110 extracts a first centerline by performing a thinning process on the extracted lumen region. Note that the extraction function 113 may extract a tubular region representing the outer shape of the tubular structure from medical image data including the tubular structure.

[0028] The tubular structure having a branch portion in a living body is, for example, a blood vessel, and particularly assumes the coronary artery of the heart. The branch portion indicates a portion where the blood vessel branches from a parent branch into a plurality of small branches. Since the lumen region is the lumen of the blood vessel, it may be called a blood vessel region.

[0029] The thinning process is, for example, a process of deleting voxels that may exist in the lumen region from the outside toward the center. Specifically, when the lumen region has a cylindrical shape, a centerline connected by one voxel is extracted by performing the thinning process on the cylindrical shape.

[0030] Note that the processing circuit 110 may detect the branch point of the first core wire by the extraction function 113. Specifically, the processing circuit 110 detects the branch point by tracking the core wire position from a plurality of end points on the first core wire, for example.

[0031] The correction function 114 is a function that generates the second core wire by correcting the first core wire extracted by the thinning process. Specifically, the processing circuit 110 generates the second core wire by correcting the position of the branch point on the first core wire based on the information of the inner cavity region and the information of the first core wire by the correction function 114.

[0032] The above "correcting the position of the branch point" is synonymous with "setting the position of the new branch point". Also, the "new branch point" may be referred to as the "branch start point". The information of the inner cavity region includes the position information of the inner cavity region and the information regarding the branch direction of the branch portion. Also, the information of the first core wire includes the position information of the first core wire.

[0033] The display control function 115 is a function that controls the display 130 to display the information during the processing or the processing result in each function or process of the processing circuit 110. Specifically, the processing circuit 110 displays the second core wire by the display control function 115. Also, the processing circuit 110 may display the branch start point and a plurality of branch end points described later together with the second core wire. Further, the processing circuit 110 may display the center point from the branch start point to each of the plurality of branch end points.

[0034] The configuration of the medical image processing apparatus 100 according to the first embodiment has been described above. Hereinafter, the medical image processing of the medical image processing apparatus 100 according to the first embodiment will be described with reference to the flowchart of FIG. 2.

[0035] FIG. 2 is a flowchart for explaining the operation of a processing circuit 110 that executes medical image processing in the first embodiment. The medical image processing in the first embodiment searches from a branch point to a branch start point and a plurality of branch end points as a process of correcting a first centerline (centerline correction process). The medical image processing shown in FIG. 2 starts according to a user's instruction.

[0036] (Step ST10) When the medical image processing starts, the processing circuit 110 executes an acquisition function 112. When executing the acquisition function 112, the processing circuit 110 acquires medical image data. Specifically, the processing circuit 110 acquires, for example, medical image data stored in the memory 120. Hereinafter, a specific example of the medical image data will be described with reference to FIG. 3.

[0037] FIG. 3 is a schematic diagram showing a specific example of medical image data MID1 in the first embodiment. Medical image data MID1 is shown in FIG. 3. The medical image data MID1 is data of a blood vessel that branches from a parent branch into two small branches. The medical image data MID1 is, for example, three-dimensional volume data taken by an X-ray CT apparatus. Therefore, the medical image data MID1 can identify a lumen region showing the inside (lumen) of the blood vessel.

[0038] (Step ST20) After acquiring the medical image data, the processing circuit 110 executes an extraction function 113. When executing the extraction function 113, the processing circuit 110 extracts a lumen region and a first centerline. Specifically, the processing circuit 110 extracts the lumen region from the medical image data, and extracts the first centerline by performing a thinning process on the lumen region. Hereinafter, specific examples of the lumen region and the first centerline will be described with reference to FIG. 4.

[0039] FIG. 4 is a schematic diagram showing specific examples of a lumen region LR1 and a first centerline CL11 in the first embodiment. In FIG. 4, a lumen region LR1 and a first centerline CL11 passing through the inside of the lumen region LR1 are shown.

[0040] According to FIG. 4, the processing circuit 110 extracts the lumen region LR1 from the medical image data MID1 using known segmentation techniques. Examples of known segmentation techniques include, for example, a method based on threshold processing of pixel values, a method using graph cut, and a method using a CNN (Convolutional Neural Network) (for example, U-Net). Also, the first method is simple but has low accuracy, and the remaining two methods have high accuracy. Then, the processing circuit 110 extracts the first core line CL11 by performing a thinning process on the lumen region LR1.

[0041] (Step ST30) After extracting the lumen region and the first core line, the processing circuit 110 detects the branch points of the first core line by the extraction function 113. Specifically, the processing circuit 110 detects the branch points by tracking the core line positions from a plurality of end points on the first core line. Hereinafter, the detection of the branch points will be described with reference to FIG. 5.

[0042] FIG. 5 is a schematic diagram for explaining the detection of the branch point BP10 of the first core line CL11 in the first embodiment. FIG. 5 shows the lumen region LR1, the first core line CL11, and the branch point BP10 on the first core line CL11.

[0043] According to FIG. 5, the processing circuit 110 detects the branch point BP10 by tracking the core line positions from three end points on the first core line CL11.

[0044] (Step ST40) After detecting the branch points of the first core line, the processing circuit 110 executes the correction function 114. When the correction function 114 is executed, the processing circuit 110 generates a second core line with the positions of the branch points on the first core line corrected. Hereinafter, the process of step ST40 will be referred to as "core line correction process". Hereinafter, a specific example of the core line correction process will be described with reference to the flowchart of FIG. 6.

[0045] FIG. 6 is a flowchart exemplifying the core wire correction process of the flowchart of FIG. 2. The flowchart of FIG. 6 transitions from step ST30. Hereinafter, each part of the lumen region LR1 shall be represented as shown in FIG. 7.

[0046] FIG. 7 is a schematic diagram for explaining each part of the lumen region LR1 in the first embodiment. FIG. 7 shows the lumen region LR1, the first core wire CL11, and the branch point BP10. In the lumen region LR1, the thick parent branch located at the upper part is called the main trunk part, and the two small branches branching from the main trunk part located at the lower part are called the first branch part and the second branch part, respectively. Specifically, in FIG. 7, the main trunk part represents the region extending upward from the branch point BP10, the first branch part represents the region extending from the branch point BP10 in the lower left direction, and the second branch part represents the region extending from the branch point BP10 in the lower right direction.

[0047] Note that the main trunk part, the first branch part, and the second branch part do not necessarily have their regions clearly distinguished in the lumen region LR1. That is, each of these parts shall at least define the direction of extension to the three endpoints on the first core wire CL11 from the branch point BP10. For example, starting from the branch point BP10, the extension direction to the main trunk part may be defined as the first direction, the extension direction to the first branch part may be defined as the second direction, and the extension direction to the second branch part may be defined as the third direction. Also, these directions may be obtained by analysis or may be given in advance.

[0048] (Step ST110) After detecting the branch point of the first core wire in step ST30, the processing circuit 110 sets three points on the first core wire at a predetermined distance from the branch point. Hereinafter, the setting of the three points near the branch point will be described with reference to FIG. 8.

[0049] FIG. 8 is a schematic diagram for explaining the setting of three points (point CP11, point CP21, and point CP31) near the branch point BP10 in the first embodiment. In FIG. 8, the lumen region LR1, the first core wire CL11, and the branch point BP10 are shown. Further, on the first core wire CL11, the branch point BP10, point CP11 on the main trunk portion, point CP21 on the first branch portion, and point CP31 on the second branch portion are shown.

[0050] According to FIG. 8, the processing circuit 110 sets three points (point CP11, point CP21, and point CP31) on the first core wire CL11 at a predetermined distance from the branch point BP10 along the core wire.

[0051] In the first embodiment, the predetermined distance is based on, for example, (1) a fixed distance from the branch point, (2) a sphere inscribed in the lumen region centered on the branch point, and (3) the size of the diameter of each part of the lumen region. Specific examples of each are described below.

[0052] (1) In the case of a fixed distance from the branch point, a value (for example, 1.0 mm) determined in advance based on previous analysis and experience is used. Note that this fixed distance is the distance from the branch point along the core wire and measures the length along the core wire starting from the branch point.

[0053] (2) In the case of a sphere inscribed in the lumen region centered on the branch point, when the radius of the sphere centered on the branch point is gradually increased (for example, by 0.5 mm at a time) from a minimum value (for example, 0.5 mm), a value (for example, 1.25 mm) that is a predetermined multiple (for example, 1 / 2 times) of the maximum radius (for example, 2.5 mm) that does not include a region other than the lumen region in the sphere (that is, includes only the lumen region (the lumen of the blood vessel)) is used.

[0054] (3) In the case of the size of the diameter of each part of the lumen region, the size of the diameter near the respective end points of the main trunk portion, the first branch portion, and the second branch portion is used. For example, a value that is a predetermined multiple (for example, 1 / 2 times) of the smallest diameter among these parts is used.

[0055] In the above (2), for example, after clarifying the voxel positions of the lumen region (blood vessel region) and the voxel positions of the regions other than the lumen region by binarization or the like, a sphere may be set to include only the lumen region. Also, for example, in setting the sphere, the voxel values themselves may be used. When using voxel values, a predetermined multiple of the maximum radius within which the variance (or standard deviation) of the voxel values of all voxels located on the surface of the sphere is within a predetermined threshold is used. That is, it is set so that only the voxel values of the blood vessel region are included inside the sphere.

[0056] In other words, the predetermined distance in the first embodiment may be based on a fixed distance, or may be based on the size of a circle or sphere inscribed in the lumen region centered on the branch point, or a predetermined geometric shape centered on the branch point that includes only the lumen region (for example, a circle or sphere) based on the size (for example, the distribution of a predetermined geometric shape in contact with the boundary of the lumen region). Note that the processing circuit 110 may calculate a predetermined distance.

[0057] (Step ST120) After setting three points on the first core wire, the processing circuit 110 creates a cross-section (reference cross-section, first cross-section) obtained by cutting the lumen region with a plane including the set three points. Hereinafter, the creation of the first cross-section will be described with reference to FIG. 9.

[0058] FIG. 9 is a schematic diagram for explaining the creation of the first cross-section CS11 in the first embodiment. In FIG. 9, on the first cross-section CS11, a left boundary line BLa11, a right boundary line BLb11, and a first core wire CL11 are shown. Also, on the first core wire CL11, a branch point BP10 and three points (point CP11, point CP21, and point CP31) are shown. The left boundary line BLa11 is continuous from the main trunk portion to the first branch portion. The right boundary line BLb11 is continuous from the main trunk portion to the second branch portion.

[0059] According to FIG. 9, the processing circuit 110 creates a first cross-section CS11 obtained by cutting the inner cavity region LR1 with a plane including three points (point CP11, point CP21, and point CP31) on the first core wire CL11. In the cross-section of FIG. 9, except for the boundary lines, what is shown is projected from a direction perpendicular to the cross-section. For example, since the core wire and each point are distributed in a three-dimensional space, they may only partially exist on the cross-section or may not exist on the cross-section. However, for the convenience of explanation, these are illustrated on the cross-section. This is the same for the following figures.

[0060] (Step ST130) After creating the first cross-section, the processing circuit 110 sets a branch start point on the first core wire passing through the main trunk. Hereinafter, the process of step ST130 will be referred to as the "branch start point setting process". Hereinafter, a specific example of the branch start point setting process will be described with reference to the flowchart of FIG. 10.

[0061] FIG. 10 is a flowchart illustrating the branch start point setting process (step ST130) of the flowchart of FIG. 6. The flowchart of FIG. 10 transitions from step ST120. In the branch start point setting process, the left boundary line or the right boundary line in the cross-section of the inner cavity region is used. Hereinafter, for the convenience of explanation, the left boundary line will be used.

[0062] (Step ST1301) After creating the first cross-section in step ST120, the processing circuit 110 sets a first boundary point closest to the branch point on the first boundary line in the first cross-section. Hereinafter, the setting of the first boundary point will be described with reference to FIG. 11. Hereinafter, the aforementioned left boundary line BLa11 will be renamed the first boundary line BLa11. Also, in each of the following figures, elements not directly related to the explanation will be omitted from the illustration and description.

[0063] FIG. 11 is a schematic diagram for explaining the setting of the first boundary point BLPa11 in the first embodiment. In FIG. 11, on the first cross-section CS11, a first boundary line BLa11 and a first core wire CL11 are shown. Further, on the first core wire CL11, a branch point BP10 and three points (point CP11, point CP21, and point CP31) are shown, and on the first boundary line BLa11, a first boundary point BLPa11 is shown.

[0064] According to FIG. 11, the processing circuit 110 sets the first boundary point BLPa11 that is closest to the branch point BP10 on the first boundary line BLa11 in the first cross-section CS11. Note that the first boundary point BLPa11 is in the direction passing between the point CP11 and the point CP21 when viewed from the branch point BP10.

[0065] (Step ST1302) After setting the first boundary point, the processing circuit 110 sets the point on the first core wire passing through the main trunk among the set three points as the first control point. Thus, hereinafter, the point CP11 is renamed as the first control point CP11.

[0066] (Step ST1303) After setting the first control point, the processing circuit 110 substitutes 1 for the variable k.

[0067] (Step ST1304) The processing circuit 110 sets the (k + 1)-th control point in the direction opposite to the branch point from the k-th control point. As a specific example, in the case after transitioning from step ST1303 (i.e., when k = 1), the processing circuit 110 sets the second control point in the direction opposite to the branch point from the first control point. Regarding this case, hereinafter, the setting of the second control point will be described with reference to FIG. 12.

[0068] FIG. 12 is a schematic diagram for explaining the setting of the second control point CP12 in the first embodiment. In FIG. 12, with respect to FIG. 11, a second control point CP12 is added on the first core wire CL11.

[0069] According to FIG. 12, the processing circuit 110 sets a second control point CP12 in the direction opposite to the branch point BP10 from the first control point CP11. At this time, the distance from the first control point CP11 to the second control point CP12 is a predetermined distance along the core wire from the branch point BP10 to the first control point CP11. Hereinafter, when newly setting a control point, the distance between the control points is the above-mentioned predetermined distance.

[0070] (Step ST1305) After setting the (k + 1)-th control point, the processing circuit 110 creates a (k + 1)-th cross section obtained by cutting the inner cavity region with a plane including the k-th boundary point, the k-th control point, and the (k + 1)-th control point. As a specific example, when k = 1, the processing circuit 110 creates a second cross section obtained by cutting the inner cavity region with a plane including the first boundary point, the first control point, and the second control point. Regarding this case, hereinafter, the creation of the second cross section will be described with reference to FIG. 13.

[0071] FIG. 13 is a schematic diagram for explaining the creation of the second cross section CS12 in the first embodiment. In FIG. 13, a second boundary line BLa12 and a first core wire CL11 are shown on the second cross section CS12. Further, on the first core wire CL11, a branch point BP10, a first control point CP11, and a second control point CP12 are shown, and a first boundary point BLPa11 is shown on the second boundary line BLa12. Note that the first boundary point BLPa11 is a point on the first boundary line BLa11, and in FIG. 13, it is assumed to be projected onto the second boundary line BLa12. This is the same in the following figures.

[0072] According to FIG. 13, the processing circuit 110 creates a second cross section CS12 obtained by cutting the inner cavity region LR1 with a plane including the first boundary point BLPa11, the first control point CP11, and the second control point CP12.

[0073] (Step ST1306) After creating the (k + 1)-th cross-section, the processing circuit 110 sets the (k + 1)-th boundary point closest to the k-th control point on the (k + 1)-th boundary line in the (k + 1)-th cross-section. As a specific example, when k = 1, the processing circuit 110 sets the second boundary point closest to the first control point on the second boundary line in the second cross-section. Regarding this case, the setting of the second boundary point will be described below with reference to FIG. 14.

[0074] FIG. 14 is a schematic diagram for explaining the setting of the second boundary point BLPa12 in the first embodiment. In FIG. 14, with respect to FIG. 13, the second boundary point BLPa12 is added on the second boundary line BLa12.

[0075] According to FIG. 14, the processing circuit 110 sets the second boundary point BLPa12 closest to the first control point CP11 on the second boundary line BLa12 in the second cross-section CS12. Note that the second boundary point BLPa12 is in the direction passing between the first boundary point BLPa11 and the second control point CP12 as viewed from the first control point CP11.

[0076] (Step ST1307) After setting the (k + 1)-th boundary point, the processing circuit 110 sets the k-th core line segment connecting the k-th control point and the (k + 1)-th control point. As a specific example, when k = 1, the processing circuit 110 sets the first core line segment connecting the first control point and the second control point.

[0077] (Step ST1308) After setting the k-th core line segment, the processing circuit 110 sets the k-th boundary line segment connecting the k-th control point and the (k + 1)-th boundary point. As a specific example, when k = 1, the processing circuit 110 sets the first boundary line segment connecting the first control point and the second boundary point.

[0078] (Step ST1309) After setting the k-th boundary line segment, the processing circuit 110 calculates the internal angle θk between the k-th core line segment and the k-th boundary line segment. As a specific example, when k = 1, the processing circuit 110 calculates the internal angle θ1 between the first core line segment and the first boundary line segment. Hereinafter, the processing from step ST1307 to step ST1309 will be described with reference to FIG. 15.

[0079] FIG. 15 is a schematic diagram for explaining the internal angle θ1 between the first core line segment sCP11 and the first boundary line segment sBLPa11 in the first embodiment. FIG. 15 shows the first control point CP11, the second control point CP12, and the second boundary point BLPa12 extracted from FIG. 14. Further, FIG. 15 shows the first core line segment sCP11 connecting the first control point CP11 and the second control point CP12 and the first boundary line segment sBLPa11 connecting the first control point CP11 and the second boundary point BLPa12.

[0080] In FIG. 15, the processing circuit 110 sets the first core line segment sCP11 and the first boundary line segment sBLPa11, and calculates the internal angle θ1 between the first core line segment sCP11 and the first boundary line segment sBLPa11.

[0081] (Step ST1310) After calculating the internal angle θk, the processing circuit 110 determines whether the internal angle θk is approximately 90 degrees. If it is determined that the internal angle θk is not approximately 90 degrees, the process proceeds to step ST1311. If it is determined that the internal angle θk is approximately 90 degrees, the process proceeds to step ST1312. Note that the internal angle θk being approximately 90 degrees means that the k-th core line segment and the k + 1-th boundary line are approximately parallel.

[0082] (Step ST1311) After determining that the internal angle θk is not approximately 90 degrees, the processing circuit 110 increments the variable k by 1.

[0083] (Step ST1312) After it is determined that the internal angle θk is approximately 90 degrees, the processing circuit 110 sets the k-th control point as the branch start point. After step ST1312, the process proceeds to step ST140 in FIG. 6. Hereinafter, the setting of the branch start point will be described with reference to FIG. 16.

[0084] FIG. 16 is a schematic diagram for explaining the setting of the branch start point BSP10 in the first embodiment. In FIG. 16, on the fourth cross-section CS14, the fourth boundary line BLa14 and the first core wire CL11 are shown. Also, on the first core wire CL11, a branch point BP10, a first control point CP11, a second control point CP12, a third control point CP13, and a fourth control point CP14 are shown in order, and on the fourth boundary line BLa14, a first boundary point BLPa11, a second boundary point BLPa12, a third boundary point BLPa13, and a fourth boundary point BLPa14 are shown in order. Note that in FIG. 16, it is assumed that the internal angle θ3 between the third core wire segment connecting the third control point CP13 and the fourth control point CP14 and the third boundary line segment connecting the third control point CP13 and the fourth boundary point BLPa14 is approximately 90 degrees.

[0085] According to FIG. 16, since the internal angle θ3 (not shown) is approximately 90 degrees, the processing circuit 110 sets the third control point CP13 as the branch start point BSP10.

[0086] (Step ST140) After setting the branch start point, the processing circuit 110 sets the first branch end point on the first core wire passing through the first branch portion. Hereinafter, the process of step ST140 will be referred to as the "first branch end point setting process". Since the first branch end point setting process is substantially the same as the branch start point setting process, a detailed description thereof will be omitted. For example, the first branch end point setting process is different from the branch start point setting process in that a control point is set on the first core wire passing through the first branch portion. Hereinafter, the setting of the first branch end point will be described with reference to FIG. 17.

[0087] FIG. 17 is a schematic diagram for explaining the setting of the first branch end point BEP11 in the first embodiment. In FIG. 17, on the sixth cross-section CS16, the sixth boundary line BLa16 and the first core wire CL11 are shown. Also, on the first core wire CL11, a branch point BP10, and in the first branch portion, a fifth control point CP21, a sixth control point CP22, and a seventh control point CP23 are sequentially shown starting from the branch point BP10. On the sixth boundary line BLa16, in the first branch portion, a fifth boundary point BLPa15 and a sixth boundary point BLPa16 are sequentially shown starting from the first boundary point BLPa11. In FIG. 17, it is assumed that the inner angle θ6 between the sixth core wire segment connecting the sixth control point CP22 and the seventh control point CP23 and the sixth boundary segment connecting the sixth control point CP22 and the sixth boundary point BLPa16 is approximately 90 degrees.

[0088] According to FIG. 17, since the inner angle θ6 (not shown) is approximately 90 degrees, the processing circuit 110 sets the sixth control point CP22 as the first branch end point BEP11.

[0089] (Step ST150) After setting the first branch end point, the processing circuit 110 creates a first partial core wire connecting the branch start point and the first branch end point. Hereinafter, the process of step ST150 will be referred to as the "first partial core wire creation process". Hereinafter, a specific example of the first partial core wire creation process will be described with reference to the flowchart of FIG. 18.

[0090] FIG. 18 is a flowchart illustrating the first partial core wire creation process (step ST150) of the flowchart of FIG. 6. The flowchart of FIG. 18 transitions from step ST140 of FIG. 6. Hereinafter, the boundary segments connecting each point on the left boundary line from the main trunk portion to the first branch portion and each point on the first core wire will be described with reference to FIG. 19.

[0091] FIG. 19 is a schematic diagram for explaining a plurality of boundary line segments related to the first branch portion in the first embodiment. In FIG. 19, on a cross-section CS1n (an arbitrary cross-section), a boundary line BLa1n (an arbitrary boundary line) and a first core wire CL11 are shown. Further, on the first core wire CL11, points A0 to A5 corresponding to each point (five control points and branch points) from the branch start point BSP10 of the main trunk portion to the first branch end point BEP11 of the first branch portion are shown. Specifically, point A0 corresponds to the branch start point BSP10 (the third control point CP13), point A1 corresponds to the second control point CP12, point A2 corresponds to the first control point CP11, point A3 corresponds to the branch point BP10, point 4 corresponds to the fifth control point CP21, and point A5 corresponds to the first branch end point BEP11 (the sixth control point CP22).

[0092] Furthermore, on an arbitrary boundary line in FIG. 19, points B0 to B5 corresponding to each point (six boundary points) from the fourth boundary point BLPa14 of the main trunk portion to the sixth boundary point BLPa16 of the first branch portion are shown. Specifically, point B0 corresponds to the fourth boundary point BLPa14, point B1 corresponds to the third boundary point BLPa13, point B2 corresponds to the second boundary point BLPa12, point B3 corresponds to the first boundary point BLPa11, point B4 corresponds to the fifth boundary point BLPa15, and point B5 corresponds to the sixth boundary point BLPa16.

[0093] Moreover, in FIG. 19, a boundary line segment sAB0 connecting point A0 and point B0, a boundary line segment sAB1 connecting point A1 and point B1, a boundary line segment sAB2 connecting point A2 and point B2, a boundary line segment sAB3 connecting point A3 and point B3, a boundary line segment sAB4 connecting point A4 and point B4, and a boundary line segment sAB5 connecting point A5 and point B5 are shown.

[0094] (Step ST1501) After setting the first branch end point, the processing circuit 110 sets new points on the boundary line segments set between the branch start point and the first branch end point. Hereinafter, the setting of new points on the boundary line segments will be described with reference to FIG. 20.

[0095] FIG. 20 is a schematic diagram for explaining the setting of new points on the boundary line segment regarding the first branch portion in the first embodiment. In FIG. 20, with respect to FIG. 19, a new point AB0 is added on the boundary line segment sAB0, a new point AB1 on the boundary line segment sAB1, a new point AB2 on the boundary line segment sAB2, a new point AB3 on the boundary line segment sAB3, a new point AB4 on the boundary line segment sAB4, and a new point AB5 on the boundary line segment sAB5 are respectively added.

[0096] Here, the maximum value 5 of the numbers attached to the line segment and each point is defined as M, and the length from the point Bk (k = 0 to M) to the new point AB0 is defined as the line segment length Lk. For example, if k = 0, the length from the point B0 to the new point AB0 is the line segment length L0. This line segment length Lk can be obtained by the following formula (1).

[0097] Lk = L0·w + LM·(1 - w) (1) Here, w = (M - k)÷M. According to the above formula (1), the value gradually decreases or increases from the line segment length L0 to the line segment length L5.

[0098] According to FIG. 20, the processing circuit 110 sets new points (new point AB1, new point AB2, new point AB3, and new point AB4) on the boundary line segments (boundary line segment sAB1, boundary line segment sAB2, boundary line segment sAB3, and boundary line segment sAB4) set between the branch start point BSP10 (corresponding to the new point AB0) and the first branch end point BEP11 (corresponding to the new point AB5). Specifically, the processing circuit 110 calculates the line segment length Lk from the point Bk using the above formula (1), and sets the point on the boundary line segment sABk that is at a distance of the line segment length Lk from the point Bk as the new point ABk.

[0099] (Step ST1502) After setting a plurality of new points, the processing circuit 110 creates a curve from the branch start point to the first branch end point so as to pass through the set plurality of new points. Hereinafter, the creation of the curve from the branch start point to the first branch end point will be described with reference to FIG. 21.

[0100] FIG. 21 is a schematic diagram for explaining the creation of a curve PCL11 from a branch start point BSP10 to a first branch end point BEP11 in the first embodiment. In FIG. 21, a curve PCL11 is added on a plurality of new points with respect to FIG. 20.

[0101] According to FIG. 21, the processing circuit 110 uses a known interpolation technique to create a curve PCL11 from a branch start point BSP10 (corresponding to new point AB0) to a first branch end point BEP11 (corresponding to new point AB5) so as to pass through a plurality of new points (new point AB1, new point AB2, new point AB3, and new point AB4). Known interpolation techniques include, for example, spline interpolation techniques in three-dimensional space.

[0102] (Step ST1503) After creating the curve, the processing circuit 110 sets the created curve to the first partial core wire. Specifically, the processing circuit 110 sets the created curve PCL11 to the first partial core wire PCL11. After step ST1503, the process proceeds to step ST160 in FIG. 6.

[0103] (Step ST160) After setting the first partial core wire, the processing circuit 110 sets a second branch end point on the first core wire passing through the second branch portion. Hereinafter, the process of step ST160 is referred to as "second branch end point setting process". Hereinafter, the preprocessing before executing the second branch end point setting process and the setting of the second branch end point will be described with reference to FIGS. 22 and 23.

[0104] FIG. 22 is a schematic diagram for explaining the preprocessing before executing the second branch end point setting process in the first embodiment. As preprocessing before executing the second branch end point setting process, it is necessary to set a boundary point on the right boundary line in the cross section of the lumen region. This preprocessing is required for the process of connecting the branch start point and the second branch end point later.

[0105] In FIG. 22, on a cross-section CS2m (an arbitrary cross-section), a boundary line BLb2m (an arbitrary boundary line) and a first core wire CL11 are shown. Further, on the first core wire CL11, a branch point BP10, a first control point CP11, a second control point CP12, a third control point CP13 (corresponding to a branch start point BSP10), and a fourth control point CP14 are shown in order. On an arbitrary boundary line, a boundary point BLPb21 set using the branch point BP10, a boundary point BLPb22 set using the first control point CP11, a boundary point BLPb23 set using the second control point CP12, and a boundary point BLPb24 set using the third control point CP13 are shown. Note that in FIG. 22, it is assumed that the interior angle between the core wire segment connecting the third control point CP13 and the fourth control point CP14 and the boundary line segment connecting the third control point CP13 and the boundary point BLPb24 is approximately 90 degrees.

[0106] The fact that the interior angle θ3 described with reference to FIG. 16 becomes approximately 90 degrees at the control point CP13 and the fact that the interior angle described with reference to FIG. 22 becomes approximately 90 degrees at the same control point CP13 are likely to occur frequently, but it is not an inevitable coincidence. For example, the interior angle described with reference to FIG. 22 may become approximately 90 degrees at the control point CP12 or the control point CP14.

[0107] The above preprocessing may be incorporated into the branch start point setting process of step ST130. That is, in the branch start point setting process, boundary points may be set for both the left boundary line and the right boundary line.

[0108] FIG. 23 is a schematic diagram for explaining the setting of the second branch end point BEP12 in the first embodiment. In FIG. 23, on a cross section CS2n (an arbitrary cross section), a boundary line BLb2n (an arbitrary boundary line) and a first core wire CL11 are shown. Further, on the first core wire CL11, a branch point BP10 and, in the second branch portion, a control point CP31, a control point CP32, and a control point CP33 are shown in order starting from the branch point BP10. On an arbitrary boundary line, in the second branch portion, a boundary point BLPb25 and a boundary point BLPb26 are shown in order starting from a boundary point BLPb21. Note that in FIG. 23, it is assumed that the internal angle between the core wire segment connecting the control points CP32 and CP33 and the boundary line segment connecting the control points CP32 and BLPb26 is approximately 90 degrees.

[0109] Note that the fact that the internal angle θ6 described with reference to FIG. 17 becomes approximately 90 degrees at the control point CP22 and the fact that the internal angle described with reference to FIG. 23 becomes approximately 90 degrees at the control point CP32 are not necessarily in agreement. For example, the internal angle described with reference to FIG. 23 may become approximately 90 degrees at the control point CP33 or a control point CP34 (not shown).

[0110] According to FIG. 23, since the internal angle related to the control point CP32 is approximately 90 degrees, the processing circuit 110 sets the control point CP32 as the second branch end point BEP12.

[0111] (Step ST170) After setting the second branch end point, the processing circuit 110 creates a second partial core wire connecting the branch start point and the second branch end point. After step ST170, the process proceeds to step ST50 in FIG. 2. Hereinafter, the process of step ST170 is referred to as the "second partial core wire creation process". Since the second partial core wire creation process is substantially the same as the first partial core wire creation process, a detailed description thereof is omitted. Hereinafter, with reference to FIG. 24 for each point on the right boundary line from the main trunk portion to the second branch portion and the boundary line segment connecting each point on the first core wire, with reference to FIG. 25 for setting a new point on the boundary line segment, and with reference to FIG. 26 for creating a curve from the branch start point to the second branch end point.

[0112] FIG. 24 is a schematic diagram for explaining a plurality of boundary line segments related to the second branch portion in the first embodiment. In FIG. 24, on a cross-section CS2n (an arbitrary cross-section), a boundary line BLb2n (an arbitrary boundary line) and a first core wire CL11 are shown. Further, on the first core wire CL11, from a branch start point BSP10 of the main trunk portion, points C0 to C5 corresponding to each point (five control points and branch points) up to a second branch end point BEP12 of the second branch portion are shown. Specifically, point C0 corresponds to the branch start point BSP10, and point C5 corresponds to the second branch end point BEP12.

[0113] Furthermore, on an arbitrary boundary line in FIG. 24, a boundary point D0 corresponding to point C0, a boundary point D1 corresponding to point C1, a boundary point D2 corresponding to point C2, a boundary point D3 corresponding to point C3, a boundary point D4 corresponding to point C4, and a boundary point D5 corresponding to point C5 are shown.

[0114] Moreover, in FIG. 24, a boundary line segment sCD0 connecting point C0 and boundary point D0, a boundary line segment sCD1 connecting point C1 and boundary point D1, a boundary line segment sCD2 connecting point C2 and boundary point D2, a boundary line segment sCD3 connecting point C3 and boundary point D3, a boundary line segment sCD4 connecting point C4 and boundary point D4, and a boundary line segment sCD5 connecting point C5 and boundary point D5 are shown.

[0115] FIG. 25 is a schematic diagram for explaining the setting of new points on the boundary line segment related to the second branch portion in the first embodiment. In FIG. 25, with respect to FIG. 24, a new point CD0 is added on the boundary line segment sCD0, a new point CD1 on the boundary line segment sCD1, a new point CD2 on the boundary line segment sCD2, a new point CD3 on the boundary line segment sCD3, a new point CD4 on the boundary line segment sCD4, and a new point CD5 on the boundary line segment sCD5 are respectively added. Note that the method of setting new points on the boundary line segment may be the same as the method described in step ST1501 of FIG. 18, so the description is omitted.

[0116] According to FIG. 25, the processing circuit 110 sets new points (new point CD1, new point CD2, new point CD3, and new point CD4) on the boundary line segments (boundary line segment sCD1, boundary line segment sCD2, boundary line segment sCD3, and boundary line segment sCD4) set between the branch start point BSP10 (corresponding to the new point CD0) and the second branch end point BEP12 (corresponding to the new point CD5).

[0117] FIG. 26 is a schematic diagram for explaining the creation of the curve PCL12 from the branch start point to the second branch end point in the first embodiment. In FIG. 26, a curve PCL12 is added on a plurality of new points with respect to FIG. 25.

[0118] According to FIG. 26, the processing circuit 110 creates a curve PCL12 from the branch start point BSP10 (corresponding to the new point CD0) to the second branch end point BEP12 (corresponding to the new point CD5) so as to pass through a plurality of new points (new point CD1, new point CD2, new point CD3, and new point CD4) using a known interpolation technique.

[0119] After creating the curve, the processing circuit 110 sets the created curve on the second partial core wire. Specifically, the processing circuit 110 sets the created curve PCL12 on the second partial core wire PCL12.

[0120] In other words, for the processing of step ST40 above, the processing circuit 110 generates a second core wire with the position of the branch point in the first core wire corrected based on the information of the lumen region and the information of the first core wire. Specifically, the processing circuit 110 uses the distance from the branch point to the first point on the boundary of the lumen region (boundary line segment related to the branch point), the distance from the branch start point to the second point on the boundary of the lumen region different from the first point (boundary line segment related to the main trunk), and the distances from a plurality of branch end points to a plurality of points on the boundary of the lumen region different from the first point and the second point respectively (boundary line segments related to the first branch part and the second branch part) to generate the second core wire.

[0121] More specifically, the processing circuit 110 sets a plurality of control points on the first core wire, sets a branch start point and a plurality of branch end points based on the branch point, the plurality of control points, and the lumen region, and generates a second core wire based on the branch point, the plurality of control points, the lumen region, the branch start point, and the plurality of branch end points.

[0122] As another expression, for each of a first direction which is the extending direction of the main trunk starting from the branch point, a second direction which is the extending direction of the first branch starting from the branch point, and a third direction which is the extending direction of the second branch starting from the branch point, the processing circuit 110 sets control points on the first core wire at predetermined distances from the branch point, and sets the control points that satisfy a predetermined condition as the branch start point for the first direction, the first branch end point for the second direction, and the second branch end point for the third direction, and generates a second core wire that branches from the branch start point to the first branch end point and the second branch end point respectively. Here, the above-mentioned predetermined condition is that the internal angle between the line segment connecting the control point and the boundary point of the lumen region and the line segment connecting the control point and another control point on the first core wire at a predetermined distance from the control point in the direction opposite to the branch point is approximately 90 degrees.

[0123] After the above step ST40, the processing circuit 110 deletes the partial core wire from the branch point BP10 to the branch start point BSP10, the partial core wire from the branch point BP10 to the first branch end point BEP11, and the partial core wire from the branch point BP10 to the second branch end point BEP12 on the first core wire CL11. Then, the processing circuit 110 can create the second core wire CL12 by adding the first partial core wire PCL11 from the branch start point BSP10 to the first branch end point BEP11 and the second partial core wire PCL12 from the branch start point BSP10 to the second branch end point BEP12.

[0124] (Step ST50) After creating the second core wire, the processing circuit 110 executes the display control function 115. When the display control function 115 is executed, the processing circuit 110 displays a second core wire including a branch start point and a plurality of branch end points. Hereinafter, the display of the second core wire including the branch start point and the plurality of branch end points will be described with reference to FIG. 27.

[0125] FIG. 27 is a schematic diagram for explaining the display of a second core wire including a branch start point and a plurality of branch end points in the first embodiment. In FIG. 27, on a cross-section CSn (an arbitrary cross-section), a left boundary line BLan, a right boundary line BLbn, and a second core wire CL12 are shown. Further, on the second core wire CL12, a branch start point BSP10, a first partial core wire PCL11, a first branch end point BEP11, a second partial core wire PCL12, and a second branch end point BEP12 are shown.

[0126] According to FIG. 27, the processing circuit 110 displays a second core wire CL12 including a branch start point BSP10, a first branch end point BEP11, and a second branch end point BEP12. Incidentally, the processing circuit 110 may display a first core wire CL11 including a branch point BP10 together with the second core wire CL12. By displaying both the first core wire CL11 and the second core wire CL12, the user can confirm the state of the core wire before and after correction.

[0127] Further, the processing circuit 110 may set the center points on the partial core wires (the first partial core wire PCL11 and the second partial core wire PCL12) from the branch start point to each of the plurality of branch end points as a plurality of branch center points on the second core wire. At this time, the processing circuit 110 displays a second core wire including a branch start point, a plurality of branch end points, and a plurality of branch center points. Hereinafter, the second core wire including a branch start point, a plurality of branch end points, and a plurality of branch center points will be described with reference to FIG. 28.

[0128] FIG. 28 is a schematic diagram for explaining the display of a second core wire including a branch start point, a plurality of branch end points, and a plurality of branch center points in the first embodiment. In FIG. 28, with respect to FIG. 27, a first branch center point BMP11 is added on the first partial core wire PCL11, and a second branch center point BMP12 is added on the second partial core wire PCL12.

[0129] According to FIG. 28, the processing circuit 110 displays a second core wire CL12 including a branch start point BSP10, a first branch end point BEP11, a second branch end point BEP12, a first branch center point BMP11, and a second branch center point BMP12.

[0130] In FIGS. 27 and 28, the processing circuit 110 displays the second core wire CL12 in an arbitrary cross section of the lumen region LR1, but the display method is not limited to this. For example, it may be displayed three-dimensionally as shown in FIG. 4. That is, the processing circuit 110 may display the lumen region LR1 and the second core wire CL12 passing through the inside of the lumen region LR1.

[0131] As described above, the medical image processing apparatus according to the first embodiment extracts a lumen region, which is an internal region of a tubular structure having a branch portion in a living body, from medical image data including the tubular structure, performs thinning processing on the lumen region to extract a first core wire, and generates a second core wire in which the position of a branch point on the first core wire is corrected based on the information of the lumen region and the information of the first core wire.

[0132] Further, the lumen region has a main trunk portion and a plurality of branch portions branching from the main trunk portion. The medical image processing apparatus according to the first embodiment sets a branch start point, which is a new branch point, on the first core wire by moving the branch point in the extending direction of the main trunk portion starting from the branch portion, and generates the second core wire branching from the branch start point.

[0133] In addition, the medical image processing apparatus according to the first embodiment sets a plurality of branch end points on the first core line in the extending direction of each of the plurality of branch portions starting from the branch point, and generates the second core line that branches from the branch start point to each of the plurality of branch end points.

[0134] Further, the medical image processing apparatus according to the first embodiment sets a plurality of control points on the first core line, and sets the branch start point and the plurality of branch end points based on the branch point, the plurality of control points, and the lumen region, and generates the second core line based on the branch point, the plurality of control points, the lumen region, the branch start point, and the plurality of branch end points.

[0135] Therefore, the medical image processing apparatus according to the first embodiment can correct the core line in the vicinity of the branch portion of the tubular structure by correcting the branch point on the core line to an appropriate position.

[0136] In addition, the medical image processing apparatus according to the first embodiment can correct the core line (first core line) extracted by the thinning process and use the corrected core line (second core line) for diagnosis and analysis. Hereinafter, with respect to the corrected core line, an extended image centered on the core line of the branching blood vessel and a multi-sectional image orthogonal to the core line of the branching blood vessel will be described with reference to FIGS. 29 and 30, respectively.

[0137] FIG. 29 is a schematic diagram for explaining an extended image centered on the corrected core line in the first embodiment. FIG. 29 shows a cross section 200 and an extended image 300. The cross section 200 is an arbitrary cross section in the three-dimensional medical image data. Further, in the cross section 200, the core line 210 is projected as viewed from a direction perpendicular to the cross section. The extended image 300 is an image obtained by deforming the cross section 200 so that the core line 210 branching to the left becomes a straight line.

[0138] In cross-section 200, when paying attention to the core wire 210 that branches to the left and the boundary line 220 located on the left, the distance d2' between the core wire 210 and the boundary line 220 at the branch point is approximately the middle (average) of the distance d1 between the core wire 210 and the boundary line 220 before branching and the distance d3 between the core wire 210 and the boundary line 220 after branching. By using the corrected core wire 210, when performing an expansion process centered on the core wire 210 that branches to the left with respect to cross-section 200, it is possible to eliminate the unnatural bulge as shown in FIG. 76 in the vicinity of the branch point where the distance d2' is shown.

[0139] FIG. 30 is a schematic diagram for explaining a multi-cross-sectional image orthogonal to the corrected core wire in the first embodiment. FIG. 30 shows a lumen region 400 extracted from medical image data and three cross-sectional images 510, 520, 530. In the lumen region 400, a core wire 410, a cross-section 420 of the blood vessel before branching, a cross-section 430 of the blood vessel at the branch point, and a cross-section 440 of the blood vessel after branching are shown. The three cross-sectional images 510, 520, 530 are images corresponding to the cross-sections 420, 430, and 440 of the lumen region 400, respectively.

[0140] In FIG. 30, the three cross-sectional images 510, 520, 530 are shown in the order of each position along the running direction of the blood vessel (each position from the upstream to the downstream of the blood vessel). The distance d2' between the center of the blood vessel and the left wall surface of the cross-sectional image 520 at position p2 is approximately the middle (average) of the distance d1 between the center of the blood vessel and the left wall surface of the cross-sectional image 510 at position p1 and the distance d3 between the center of the blood vessel and the left wall surface of the cross-sectional image 530 at position p3. By using the corrected core wire 410, when displaying a multi-cross-sectional image of the blood vessel, it is possible to eliminate the unnatural bulge of the blood vessel as shown in FIG. 77 at time t2 near the branch point.

[0141] As described above, it can be said that the corrected core wire in the first embodiment has no distortion at the branch point. Since there is no distortion in the core wire, the corrected core wire is considered to be more convenient for diagnosis and analysis than the conventional distorted core wire.

[0142] (Modification of the First Embodiment) For the medical image processing apparatus according to the first embodiment, the core line correction process was performed on normal blood vessels. Normal blood vessels are, for example, blood vessels without plaques on the vessel wall or without calcification visible on the vessel wall. On the other hand, for the medical image processing apparatus according to a modification of the first embodiment, for example, the core line correction process is performed on blood vessels with plaques. Hereinafter, a cross-section with plaques will be described with reference to FIG. 31.

[0143] FIG. 31 is a schematic diagram showing a specific example of a cross-section of a medical image in which a blood vessel with plaques in a modification of the first embodiment is shown. In FIG. 31, on a cross-section CS1n (an arbitrary cross-section), a boundary line BLa1n (an arbitrary boundary line) and a first core line CL11 are shown. Also, on an arbitrary boundary line, a plaque PL can be seen on the trunk side. The arbitrary boundary line has a convex shape in the direction of the center of the lumen region at the portion of the plaque PL. Hereinafter, the setting of the branch start point in the case of having plaques will be described with reference to FIG. 32.

[0144] FIG. 32 is a schematic diagram for explaining the setting of the branch start point in the case of having plaques in a modification of the first embodiment. FIG. 32 corresponds to the explanation of step ST1312 in the flowchart of FIG. 10. In FIG. 32, on a fourth cross-section CS14’, a fourth boundary line BLa14’ and a first core line CL11 are shown. Also, on the first core line CL11, a branch point BP10, a first control point CP11, a second control point CP12, a third control point CP13, and a fourth control point CP14 are shown in order, and on the fourth boundary line BLa14’, there is a plaque PL, and a first boundary point BLPa11, a second boundary point BLPa12, a third boundary point BLPa13’, and a fourth boundary point BLPa14’ are shown in order. Note that in FIG. 32, it is assumed that the internal angle θ3 between the core line segment connecting the third control point CP13 and the fourth control point CP14 and the boundary line segment connecting the third control point CP13 and the fourth boundary point BLPa14’ is approximately 90 degrees.

[0145] According to FIG. 32, since the inner angle θ3 (not shown) is approximately 90 degrees, the processing circuit 110 sets the third control point CP13 as the branch start point BSP10. Note that depending on the shape of the plaque PL, significant distortion may occur in the first core wire CL11 near the plaque PL. In such a case, a control point different from the control point (the third control point CP13) described above (for example, the second control point CP12 or the fourth control point CP14, etc.) may be set as the branch start point. However, this only reflects the difference in blood vessel shape and is considered to be not much different from the processing for normal blood vessels.

[0146] As described above, even if there is a plaque PL in the lumen region, the processing of the flowchart in FIG. 10 can set the branch start point at an appropriate position. Therefore, the medical image processing apparatus according to the modification of the first embodiment can correct the core wire near the branch portion of the tubular structure, similar to the medical image processing apparatus of the first embodiment.

[0147] (Second Embodiment) The medical image processing apparatus according to the first embodiment searched from the branch point to the branch start point and a plurality of branch end points in the core wire correction process. On the other hand, the medical image processing apparatus according to the second embodiment sets positions separated from the branch point by a predetermined distance as the branch start point and a plurality of branch end points.

[0148] The medical image processing apparatus according to the second embodiment has substantially the same configuration as the medical image processing apparatus according to the first embodiment. Therefore, the description of the configuration of the medical image processing apparatus according to the second embodiment is omitted.

[0149] The medical image processing apparatus according to the second embodiment differs in the processing of step ST40 in the flowchart of FIG. 2. In the medical image processing apparatus according to the second embodiment, step ST40A is performed instead of step ST40 in FIG. 2. Hereinafter, the processing of step ST40A will be referred to as "core line correction processing". Hereinafter, a specific example of the core line correction processing in the second embodiment will be described with reference to the flowchart of FIG. 33. Note that the processing target is the same as the lumen region LR1 described in the first embodiment.

[0150] FIG. 33 is a flowchart illustrating the core line correction processing (step ST40A) in the second embodiment. The flowchart of FIG. 33 transitions from step ST30 in FIG. 2.

[0151] (Step ST210) After detecting the branch point of the first core line in step ST30, the processing circuit 110 sets three points on the first core line at a predetermined distance from the branch point.

[0152] (Step ST220) After setting the three points on the first core line, the processing circuit 110 sets the set three points as the branch start point, the first branch end point, and the second branch end point, respectively. Hereinafter, the setting of the branch start point, the first branch end point, and the second branch end point will be described with reference to FIG. 34.

[0153] FIG. 34 is a schematic diagram for explaining the setting of the branch start point, the first branch end point, and the second branch end point in the second embodiment. FIG. 34 shows the lumen region LR2, the first core line CL21, and the branch point BP20. Further, on the first core line CL21, a point BSP20 is shown on the main trunk portion, a point BEP21 is shown on the first branch portion, and a point BEP22 is shown on the second branch portion.

[0154] According to FIG. 34, first, the processing circuit 110 sets three points (point BSP20, point BEP21, and point BEP22) on the first core wire CL21 at a predetermined distance from the branch point BP20. Next, the processing circuit 110 sets the three set points as the branch start point BSP20, the first branch end point BEP21, and the second branch end point BEP22, respectively.

[0155] The predetermined distance in the second embodiment is based on, for example, either (1) a fixed distance from the branch point and (2) a sphere inscribed in the lumen region centered on the branch point. Specific examples of each are described below.

[0156] (1) In the case of a fixed distance from the branch point, a value (for example, 3.0 mm) determined in advance based on previous analysis and experience is used. Note that this fixed distance is the distance away from the branch point along the core wire, and measures the length along the core wire starting from the branch point.

[0157] (2) In the case of a sphere inscribed in the lumen region centered on the branch point, when the radius of the sphere centered on the branch point is gradually increased from the minimum value, a value (for example, 2.5 mm to 3.25 mm) that is a predetermined multiple (for example, 1 to 1.3 times) of the maximum radius (for example, 2.5 mm) that does not include regions other than the lumen region in the sphere (that is, includes only the lumen region) is used. In this specific example, the thicker the blood vessel, the larger the predetermined distance.

[0158] In other words, the predetermined distance in the second embodiment may be based on the fixed distance or on the size of a predetermined geometric shape (for example, a circle or a sphere) centered on the branch point (for example, the distribution of a predetermined geometric shape in contact with the boundary of the lumen region). Note that the processing circuit 110 may calculate the predetermined distance.

[0159] (Step ST230) After setting the branch start point, the first branch end point, and the second branch end point, the processing circuit 110 sets respective reference line segments at the branch start point, the first branch end point, and the second branch end point. Hereinafter, the process of step ST230 is referred to as "reference line segment setting process". Hereinafter, a specific example of the reference line segment setting process will be described with reference to the flowchart of FIG. 35.

[0160] FIG. 35 is a flowchart illustrating the reference line segment setting process of the flowchart of FIG. 33. The flowchart of FIG. 35 transitions from step ST220.

[0161] (Step ST2301) In step ST220, after setting the branch start point, the first branch end point, and the second branch end point, the processing circuit 110 calculates the direction vector of the first core wire in the vicinity of each of the three set points. Hereinafter, the calculation of the direction vector will be described with reference to FIG. 36.

[0162] FIG. 36 is a schematic diagram for explaining the calculation of the direction vector in the second embodiment. In FIG. 36, with respect to FIG. 34, a direction vector vBSP20, a direction vector vBEP21, and a direction vector vBEP22 are added. The direction vector vBSP20 is a vector along the first core wire CL21 starting from the branch start point BSP20. The direction vector vBEP21 is a vector along the first core wire CL21 starting from the first branch end point BEP21. The direction vector vBEP22 is a vector along the first core wire CL21 starting from the second branch end point BEP22.

[0163] According to FIG. 36, the processing circuit 110 calculates the direction vector vBSP20 for the branch start point BSP20, calculates the direction vector vBEP21 for the first branch end point BEP21, and calculates the direction vector vBEP22 for the second branch end point BEP22.

[0164] (Step ST2302) After calculating the direction vector of the first core wire, the processing circuit 110 creates a region cross-section where a cross-section orthogonal to the direction vector intersects the lumen region, respectively. Hereinafter, the creation of the region cross-section will be described with reference to FIG. 37.

[0165] FIG. 37 is a schematic diagram for explaining the creation of a region cross-section in the second embodiment. In FIG. 37, a region cross-section RCS1, a region cross-section RCS2, and a region cross-section RCS3 are added to FIG. 36. The region cross-section RCS1 is a cross-section orthogonal to the direction vector vBSP20 and including the branch start point BSP20. The region cross-section RCS2 is a cross-section orthogonal to the direction vector vBEP21 and including the first branch end point BEP21. The region cross-section RCS3 is a cross-section orthogonal to the direction vector vBEP22 and including the second branch end point BEP22.

[0166] According to FIG. 37, the processing circuit 110 creates a region cross-section RCS1 where a cross-section orthogonal to the direction vector vBSP20 intersects the lumen region LR2, creates a region cross-section RCS2 where a cross-section orthogonal to the direction vector vBEP21 intersects the lumen region LR2, and creates a region cross-section RCS3 where a cross-section orthogonal to the direction vector vBEP22 intersects the lumen region LR2.

[0167] (Step ST2303) After creating the region cross-section, the processing circuit 110 creates a reference cross-section obtained by cutting the lumen region with a plane including the set three points (branch start point BSP20, first branch end point BEP21, and second branch end point BEP22).

[0168] (Step ST2304) After creating the reference cross-section, the processing circuit 110 sets reference line segments (four line segments described later) where the reference cross-section intersects each region cross-section (region cross-section RCS1, region cross-section RCS2, and region cross-section RCS3). After step ST2304, the process proceeds to step ST240 in FIG. 33. Hereinafter, the creation of the reference cross-section and the setting of the reference line segments will be described with reference to FIG. 38.

[0169] FIG. 38 is a schematic diagram for explaining the creation of a reference cross-section and the setting of reference line segments in the second embodiment. In FIG. 38, on the reference cross-section CS31, a left boundary line BLa31, a right boundary line BLb31, and a first core wire CL21 are shown. Further, on the first core wire CL21, a branch point BP20 and three points (a branch start point BSP20, a first branch end point BEP21, and a second branch end point BEP22) are shown.

[0170] On the left boundary line BLa31, a boundary point BLPa31S and a boundary point BLPa31E are shown. The boundary point BLPa31S is the intersection point of the aforementioned region cross-section RCS1 and the left boundary line BLa31. The boundary point BLPa31E is the intersection point of the aforementioned region cross-section RCS2 and the left boundary line BLa31.

[0171] On the right boundary line BLb31, a boundary point BLPb31S and a boundary point BLPb31E are shown. The boundary point BLPb31S is the intersection point of the aforementioned region cross-section RCS1 and the right boundary line BLb31. The boundary point BLPb31E is the intersection point of the aforementioned region cross-section RCS3 and the right boundary line BLb31.

[0172] Furthermore, on the reference cross-section CS31, a reference line segment sa31S connecting the branch start point BSP20 and the boundary point BLPa31S, a reference line segment sa31E connecting the first branch end point BEP21 and the boundary point BLPa31E, a reference line segment sb31S connecting the branch start point BSP20 and the boundary point BLPb31S, and a reference line segment sb31E connecting the second branch end point BEP22 and the boundary point BLPb31E are shown.

[0173] According to FIG. 38, first, the processing circuit 110 creates a reference cross-section CS31 obtained by cutting the inner cavity region LR2 in a plane including the set three points (branch start point BSP20, first branch end point BEP21, and second branch end point BEP22). Next, the processing circuit 110 sets reference line segments sa31S, sa31E, sb31S, and sb31E where the reference cross-section CS31 intersects with the respective region cross-sections RCS1, RCS2, and RCS3. Hereinafter, the reference line segment sa31S is renamed as the first reference line segment sa31S, and the reference line segment sa31E is renamed as the second reference line segment sa31E.

[0174] (Step ST240) After setting the reference line segments, the processing circuit 110 creates a first partial core wire connecting the branch start point and the first branch end point. Hereinafter, the process of step ST240 is referred to as the "first partial core wire creation process". Hereinafter, a specific example of the first partial core wire creation process will be described with reference to the flowchart of FIG. 39A and the flowchart of FIG. 39B. Note that FIGS. 39A and 39B are merely a formal separation of one flowchart showing the first partial core wire creation process, and hereinafter will be simply described as FIG. 39.

[0175] FIG. 39 is a flowchart illustrating the first partial core wire creation process (step ST240) of the flowchart of FIG. 33. The flowchart of FIG. 39 transitions from step ST230 (or step ST2304).

[0176] (Step ST2401) After setting the reference line segments in step ST230 (or step ST2304), the processing circuit 110 sets three nearby points on the first core wire near the branch point. Hereinafter, the setting of the three nearby points will be described with reference to FIG. 40.

[0177] FIG. 40 is a schematic diagram for explaining the setting of three nearby points in the second embodiment. In FIG. 40, on the reference cross-section CS31, a left boundary line BLa31 and a first core wire CL21 are shown. Also, on the first core wire CL21, a branch point BP20 and three nearby points (nearby point NP11, nearby point NP12, and nearby point NP13) are shown.

[0178] According to FIG. 40, the processing circuit 110 sets three nearby points (nearby point NP11, nearby point NP12, and nearby point NP13) on the first core wire CL21 near the branch point BP20. Specifically, the processing circuit 110 sets the nearby point NP11 on the main trunk part, the nearby point NP12 on the first branch part, and the nearby point NP13 on the second branch part on the first core wire CL21, respectively. Note that, for example, a predetermined distance in the first embodiment may be used as the distance from the branch point BP20 to each nearby point.

[0179] (Step ST2402) After the three nearby points are set, the processing circuit 110 creates a cross-section (nearby cross-section, first cross-section) obtained by cutting the inner cavity region with a plane including the set three nearby points. Hereinafter, the creation of the first cross-section will be described with reference to FIG. 41.

[0180] FIG. 41 is a schematic diagram for explaining the creation of the first cross-section CS32 in the second embodiment. In FIG. 41, on the first cross-section CS32, a left boundary line BLa32 and a first core wire CL21 are shown. Also, on the first core wire CL21, a branch point BP20 and three nearby points (nearby point NP11, nearby point NP12, and nearby point NP13) are shown.

[0181] According to FIG. 41, the processing circuit 110 creates a first cross-section CS32 obtained by cutting the inner cavity region LR2 with a plane including the three nearby points (nearby point NP11, nearby point NP12, and nearby point NP13) on the first core wire CL21.

[0182] (Step ST2403) After creating the first cross-section, the processing circuit 110 sets a first boundary point closest to the branch point on the first boundary line in the first cross-section. Hereinafter, the setting of the first boundary point will be described with reference to FIG. 42. Note that hereinafter, the aforementioned left boundary line BLa32 is renamed as the first boundary line BLa32.

[0183] FIG. 42 is a schematic diagram for explaining the setting of the first boundary line BLa32 in the second embodiment. In FIG. 42, a first boundary point BLPa32 is added on the first boundary line BLa32 with respect to FIG. 41. Further, FIG. 42 shows a first boundary line segment sa32 connecting the branch point BP20 and the first boundary point BLPa32.

[0184] According to FIG. 42, the processing circuit 110 sets a first boundary point BLPa32 closest to the branch point BP20 on the first boundary line BLa32 in the first cross-section CS32. Note that the first boundary point BLPa32 is in the direction passing between the neighboring point NP11 and the neighboring point NP12 when viewed from the branch point BP20.

[0185] (Step ST2404) After setting the first boundary point, the processing circuit 110 calculates a first distance based on the distance of the first reference line segment and the distance of the second reference line segment. Specifically, the processing circuit 110 calculates the average of the distance of the first reference line segment and the distance of the second reference line segment as the first distance.

[0186] (Step ST2405) After calculating the first distance, the processing circuit 110 sets a first new point on the line segment between the branch point and the first boundary point based on the first distance. Specifically, the processing circuit 110 sets the first new point at a position separated from the first boundary point by the first distance on the line segment. Hereinafter, the calculation of the first distance and the setting of the first new point will be described with reference to FIG. 43.

[0187] FIG. 43 is a schematic diagram for explaining the calculation of the first distance dE1 and the setting of the first new point E1 in the second embodiment. In FIG. 43, with respect to FIG. 42, the first new point E1 is added on the first boundary line segment sa32. Further, in FIG. 43, the first distance dE1 from the first boundary point BLPa32 to the first new point E1 is shown.

[0188] According to FIG. 43, first, the processing circuit 110 calculates the average of the distance between the first reference line segment sa31S and the second reference line segment sa31E as the first distance dE1. Next, the processing circuit 110 sets the first new point E1 at a position on the first boundary line segment sa32 that is separated from the first boundary point BLPa32 by the first distance dE1.

[0189] (Step ST2406) After setting the first new point, the processing circuit 110 sets a plurality of control points at positions that divide the section from the branch point to the branch start point on the first core wire at substantially equal intervals. For example, when dividing into three parts, there are two control points. Note that there may be one control point. Hereinafter, the setting of the plurality of control points will be described with reference to FIG. 44.

[0190] FIG. 44 is a schematic diagram for explaining the setting of a plurality of control points in the second embodiment. In FIG. 44, with respect to FIG. 43, on the first core wire CL21, the first control point CP111 and the second control point CP112 are shown between the branch point BP20 and the branch start point BSP20.

[0191] According to FIG. 44, the processing circuit 110 sets the first control point CP111 and the second control point CP112 at positions that divide the section from the branch point BP20 to the branch start point BSP20 on the first core wire CL21 into three parts.

[0192] (Step ST2407) After setting a plurality of control points, the processing circuit 110 sets a plurality of boundary points corresponding to the plurality of control points. For setting the boundary points, the method described in the first embodiment may be used. That is, the processing circuit 110 creates a cross-section obtained by cutting the inner cavity region with a plane including the boundary point set immediately before and two control points on the first core wire, and sets a new boundary point at the point on the boundary line closest to the control point closer to the branch point among the two control points in the created cross-section. Hereinafter, the setting of the plurality of boundary points will be described with reference to FIG. 45.

[0193] FIG. 45 is a schematic diagram for explaining the setting of a plurality of boundary points in the second embodiment. In FIG. 45, on the third cross-section CS34, a third boundary line BLa34 and a first core wire CL21 are shown. Further, on the first core wire CL21, a branch point BP20, a first control point CP111, a second control point CP112, and a branch start point BSP20 are shown. Further, on the third boundary line BLa34, a first boundary point BLPa32, a second boundary point BLPa33, and a third boundary point BLPa34 are shown. Furthermore, FIG. 45 shows a second boundary line segment sa33 connecting the first control point CP111 and the second boundary point BLPa33, and a third boundary line segment sa34 connecting the second control point CP112 and the third boundary point BLPa34.

[0194] According to FIG. 45, first, the processing circuit 110 creates a second cross-section CS33 (not shown) obtained by cutting the inner cavity region LR2 with a plane including the first boundary point BLPa32, the first control point CP111, and the second control point CP112, and sets the second boundary point BLPa33 at the point closest to the first control point CP111 on the second boundary line BLa33 (not shown) in the second cross-section CS33. Next, the processing circuit 110 creates a third cross-section CS34 where a plane including the second boundary point BLPa33, the second control point CP112, and the branch start point BSP20 intersects the inner cavity region LR2, and sets the third boundary point BLPa34 at the point closest to the second control point CP112 on the third boundary line BLa34 in the third cross-section CS34.

[0195] (Step ST2408) After setting a plurality of boundary points, the processing circuit 110 calculates a plurality of distances based on the distance of the first reference line segment and the first distance. Specifically, the processing circuit 110 calculates, as a plurality of distances, the weighted average value of the distance of the first reference line segment and the first distance at each control point. More specifically, the processing circuit 110 determines the coefficient of the weighted average according to the ratio of the distance from the branch point BP20 to each control point and the distance from the branch start point BSP20 to each control point, and calculates a plurality of distances.

[0196] (Step ST2409) After calculating a plurality of distances, the processing circuit 110 sets new points on each of the plurality of line segments connecting the plurality of control points and the plurality of boundary points based on the plurality of distances. Specifically, the processing circuit 110 sets a new point at a position separated from each boundary line by the distance calculated from each boundary line on each line segment. Hereinafter, the calculation of the plurality of distances and the setting of the plurality of new points will be described with reference to FIG. 46.

[0197] FIG. 46 is a schematic diagram for explaining the calculation of a plurality of distances and the setting of a plurality of new points in the second embodiment. In FIG. 46, with respect to FIG. 45, a second new point E2 is added on the second boundary line segment sa33, and a third new point E3 is added on the third boundary line segment sa34. Further, FIG. 46 shows a second distance dE2 from the second boundary point BLPa33 to the second new point E2 and a third distance dE3 from the third boundary point BLPa34 to the third new point E3.

[0198] According to FIG. 46, first, the processing circuit 110 calculates the second distance dE2 and the third distance dE3 by the above-described weighted average. Next, the processing circuit 110 sets a second new point E2 at a position separated from the second boundary point BLPa33 by the second distance dE2 on the second boundary line segment sa33. Further, the processing circuit 110 sets a third new point E3 at a position separated from the third boundary point BLPa34 by the third distance dE3 on the third boundary line segment sa34.

[0199] (Step ST2410) After setting new points on each of the plurality of line segments, the processing circuit 110 sets a plurality of control points at positions that divide the section from the branch point to the first branch end point on the first core wire at substantially equal intervals. Hereinafter, the setting of the plurality of control points will be described with reference to FIG. 47.

[0200] FIG. 47 is a schematic diagram for explaining the setting of a plurality of control points in the second embodiment. In FIG. 47, with respect to FIG. 46, on the first core wire CL21, a third control point CP211 and a fourth control point CP212 are shown between the branch point BP20 and the first branch end point BEP21.

[0201] According to FIG. 47, the processing circuit 110 sets the third control point CP211 and the fourth control point CP212 at positions that trisect the section from the branch point BP20 to the first branch end point BEP21 on the first core wire CL21.

[0202] (Step ST2411) After setting the plurality of control points, the processing circuit 110 sets a plurality of boundary points corresponding to the plurality of control points. The boundary points may be set using the method described in the first embodiment and step ST2407. Hereinafter, the setting of the plurality of boundary points will be described with reference to FIG. 48.

[0203] FIG. 48 is a schematic diagram for explaining the setting of a plurality of boundary points in the second embodiment. In FIG. 48, on the fifth cross-section CS36, a fifth boundary line BLa36 and a first core wire CL21 are shown. Further, on the first core wire CL21, a branch point BP20, a third control point CP211, a fourth control point CP212, and a first branch end point BEP21 are shown. Further, on the fifth boundary line BLa36, a first boundary point BLPa32, a fourth boundary point BLPa35, and a fifth boundary point BLPa36 are shown. Furthermore, in FIG. 48, a fourth boundary line segment sa35 connecting the third control point CP211 and the fourth boundary point BLPa35, and a fifth boundary line segment sa36 connecting the fourth control point CP212 and the fifth boundary point BLPa36 are shown. Note that the specific description of the processing circuit 110 is omitted because it is substantially the same as the description in step ST2407.

[0204] (Step ST2412) After setting a plurality of boundary lines, the processing circuit 110 calculates a plurality of distances based on the distance of the second reference line segment and the first distance. The calculation of the plurality of distances may use the method described in step ST2408.

[0205] (Step ST2413) After calculating a plurality of distances, the processing circuit 110 sets new points on each of the plurality of line segments connecting the plurality of control points and the plurality of boundary points based on the plurality of distances. Hereinafter, the calculation of the plurality of distances and the setting of the plurality of new points will be described with reference to FIG. 49.

[0206] FIG. 49 is a schematic diagram for explaining the calculation of a plurality of distances and the setting of a plurality of new points in the second embodiment. In FIG. 49, with respect to FIG. 48, a fourth new point E4 is added on the fourth boundary line segment sa35, and a fifth new point E5 is added on the fifth boundary line segment sa36. Further, in FIG. 49, a fourth distance dE4 from the fourth boundary point BLPa35 to the fourth new point E4 and a fifth distance dE5 from the fifth boundary point BLPa36 to the fifth new point E5 are shown. Note that the specific description of the processing circuit 110 is omitted because it is substantially the same as the description in step ST2409.

[0207] (Step ST2414) After setting new points on each of the plurality of line segments, the processing circuit 110 creates a curve from the branch start point to the first branch end point so as to pass through the set plurality of new points. Hereinafter, the creation of the curve from the branch start point to the first branch end point will be described with reference to FIG. 50.

[0208] FIG. 50 is a schematic diagram for explaining the creation of a curve PCL21 from a branch start point BSP20 to a first branch end point BEP21 in the second embodiment. In FIG. 50, on a cross section CS3n (an arbitrary cross section), a boundary line BLa3n (an arbitrary boundary line) and a first core wire CL21 are shown. Further, on the first core wire CL21, a branch start point BSP20 and a first branch end point BEP21 are shown. Furthermore, in FIG. 50, the curve PCL21 is shown on a plurality of new points.

[0209] According to FIG. 50, the processing circuit 110 uses a known interpolation technique to create a curve PCL21 from the branch start point BSP20 to the first branch end point BEP21 so as to pass through a plurality of new points (a third new point E3, a second new point E2, a first new point E1, a fourth new point E4, and a fifth new point E5).

[0210] (Step ST2415) After creating the curve, the processing circuit 110 sets the created curve on the first partial core wire. Specifically, the processing circuit 110 sets the created curve PCL21 on the first partial core wire PCL21. After step ST2415, the process proceeds to step ST250 in FIG. 33.

[0211] (Step ST250) After creating the first partial core wire, the processing circuit 110 creates a second partial core wire that connects the branch start point and the second branch end point. After step ST250, the process proceeds to step ST50 in FIG. 2. Hereinafter, the process of step ST250 is referred to as the "second partial core wire creation process". Since the second partial core wire creation process is substantially the same as the first partial core wire creation process, a detailed description thereof is omitted. Hereinafter, the creation of the curve from the branch start point to the second branch end point will be described with reference to FIG. 51.

[0212] FIG. 51 is a schematic diagram for explaining the creation of a curve PCL22 from a branch start point BSP20 to a second branch end point BEP22 in the second embodiment. In FIG. 51, on a cross section CS4n (an arbitrary cross section), a boundary line BLb4n (an arbitrary boundary line) and a first core wire CL21 are shown. Further, on the first core wire CL21, a branch start point BSP20 and a second branch end point BEP22 are shown. Also, new points F1, F2, F3, F4, and F5 are shown on each boundary line segment.

[0213] According to FIG. 51, the processing circuit 110 creates a curve PCL22 from the branch start point BSP20 to the second branch end point BEP22 so as to pass through a plurality of new points (new point F3, new point F2, new point F1, new point F4, and new point F5).

[0214] After creating the curve, the processing circuit 110 sets the created curve as the second partial core wire. Specifically, the processing circuit 110 sets the created curve PCL22 as the second partial core wire PCL22.

[0215] In other words, for the process of step ST40A, based on the information of the inner cavity region and the information of the first core wire, the processing circuit 110 generates a second core wire with the position of the branch point on the first core wire corrected. Specifically, the processing circuit 110 uses the distance from the branch point to the first point on the boundary of the inner cavity region (the boundary line segment related to the branch point), the distance from the branch start point to the second point on the boundary of the inner cavity region different from the first point (the boundary line segment related to the main trunk), and the distances from the plurality of branch end points to the plurality of points on the boundary of the inner cavity region different from the first point and the second point respectively (the boundary line segments related to the first branch part and the second branch part) to generate the second core wire.

[0216] More specifically, the processing circuit 110 sets the points on the first core wire at a predetermined distance from the branch point as the branch start point and the plurality of branch end points respectively, sets a plurality of control points on the first core wire based on the branch point, the branch start point, and the plurality of branch end points, and generates the second core wire based on the branch point, the plurality of control points, the inner cavity region, the branch start point, and the plurality of branch end points.

[0217] As another expression, the processing circuit 110 sets three points on the first core wire at a predetermined distance away from the branch point as the branch start point, the first branch end point, and the second branch end point respectively, and generates the second core wire that branches from the branch start point to the first branch end point and the second branch end point respectively.

[0218] After the above step ST40A, the processing circuit 110 deletes the partial core wires from the branch point BP20 to the branch start point BSP20, from the branch point BP20 to the first branch end point BEP21, and from the branch point BP20 to the second branch end point BEP22 on the first core wire CL21. Then, the processing circuit 110 creates the second core wire CL22 by adding the first partial core wire PCL21 from the branch start point BSP20 to the first branch end point BEP21 and the second partial core wire PCL22 from the branch start point BSP20 to the second branch end point BEP22. Hereinafter, the display of the second core wire including the branch start point and the plurality of branch end points will be described with reference to FIG. 52.

[0219] FIG. 52 is a schematic diagram for explaining the display of a second core wire including a branch start point and a plurality of branch end points in the second embodiment. In FIG. 52, on a cross section CSn (an arbitrary cross section), a left boundary line BLan, a right boundary line BLbn, and a second core wire CL22 are shown. Further, on the second core wire CL22, a branch start point BSP20, a first partial core wire PCL21, a first branch end point BEP21, a second partial core wire PCL22, and a second branch end point BEP22 are shown.

[0220] According to FIG. 52, the processing circuit 110 displays a second core wire CL22 including a branch start point BSP20, a first branch end point BEP21, and a second branch end point BEP22. Incidentally, the processing circuit 110 may display a first core wire CL21 including a branch point BP20 together with the second core wire CL22. By displaying both the first core wire CL21 and the second core wire CL22, the user can confirm the states of the core wire before and after correction.

[0221] As described above, similar to the first embodiment, the medical image processing apparatus according to the second embodiment extracts a lumen region, which is an internal region of a tubular structure, from medical image data including a tubular structure having a branch portion in a living body, extracts a first core wire by performing a thinning process on the lumen region, and generates a second core wire in which the position of a branch point in the first core wire is corrected based on the information of the lumen region and the information of the first core wire.

[0222] Further, the medical image processing apparatus according to the second embodiment sets points on the first core wire at a predetermined distance from the branch point as the branch start point and a plurality of branch end points respectively, sets a plurality of control points on the first core wire based on the branch point, the branch start point, and the plurality of branch end points, and generates a second core wire based on the branch point, the plurality of control points, the lumen region, the branch start point, and the plurality of branch end points.

[0223] Therefore, similar to the medical image processing apparatus according to the first embodiment, the medical image processing apparatus according to the second embodiment can correct the core wire near the branch portion of the tubular structure.

[0224] (Third Embodiment) In the first and second embodiments, as a specific example, medical image processing for a tubular structure branching into two has been described. On the other hand, in the third embodiment, as a specific example, medical image processing for a tubular structure branching into three will be described.

[0225] The medical image processing apparatus according to the third embodiment has substantially the same configuration as the medical image processing apparatus according to each of the foregoing embodiments. Therefore, the description of the configuration of the medical image processing apparatus according to the third embodiment is omitted.

[0226] FIG. 53 is a flowchart for explaining the operation of the processing circuit 110 that executes medical image processing in the third embodiment. In the medical image processing in the third embodiment, a process of analyzing the lumen structure (lumen analysis process) is added to the medical image processing in each of the foregoing embodiments. The medical image processing shown in FIG. 53 starts according to a user's instruction.

[0227] (Step ST10B) When the medical image processing starts, the processing circuit 110 executes the acquisition function 112. When the acquisition function 112 is executed, the processing circuit 110 acquires medical image data. Specifically, the processing circuit 110 acquires, for example, medical image data stored in the memory 120. Hereinafter, a specific example of the medical image data in the third embodiment will be described with reference to FIG. 54.

[0228] FIG. 54 is a schematic diagram showing a specific example of the medical image data MID3 in the third embodiment. The medical image data MID3 is shown in FIG. 54. The medical image data MID3 is data of a blood vessel branching from a parent branch into three small branches. The medical image data MID3 is three-dimensional volume data similar to the medical image data MID1 in the first embodiment and the like.

[0229] (Step ST20B) After acquiring medical image data, the processing circuit 110 executes the extraction function 113. When the extraction function 113 is executed, the processing circuit 110 extracts the lumen region and the first core wire. Specifically, the processing circuit 110 extracts the lumen region from the medical image data and extracts the first core wire by performing a thinning process on the lumen region. Hereinafter, a specific example of the lumen region and the first core wire in the third embodiment will be described with reference to FIG. 55.

[0230] FIG. 55 is a schematic diagram showing a specific example of the lumen region LR3 and the first core wire CL31 in the third embodiment. FIG. 55 shows the lumen region LR3 and the first core wire CL31 passing through the inside of the lumen region LR3.

[0231] According to FIG. 55, the processing circuit 110 extracts the lumen region LR3 from the medical image data MID3 using a known segmentation technique. Then, the processing circuit 110 extracts the first core wire CL31 by performing a thinning process on the lumen region LR3.

[0232] (Step ST30B) After extracting the lumen region and the first core wire, the processing circuit 110 detects the branch points of the first core wire by the extraction function 113. Specifically, the processing circuit 110 detects the branch points by tracking the core wire positions from a plurality of end points on the first core wire. Hereinafter, the detection of the branch points in the third embodiment will be described with reference to FIG. 56.

[0233] FIG. 56 is a schematic diagram for explaining the detection of the branch point BP30 of the first core wire CL31 in the third embodiment. FIG. 56 shows the lumen region LR3, the first core wire CL31, and the branch point BP30 on the first core wire CL31.

[0234] According to FIG. 56, the processing circuit 110 detects the branch point BP30 by tracking the core wire positions from four end points on the first core wire CL31.

[0235] (Step ST300) After detecting the branch point of the first core wire, the processing circuit 110 executes lumen analysis processing. Hereinafter, a specific example of the lumen analysis processing will be described with reference to the flowchart of FIG. 57.

[0236] FIG. 57 is a flowchart illustrating the lumen analysis processing of the flowchart of FIG. 53. The flowchart of FIG. 57 transitions from step ST30B. Hereinafter, each part of the lumen region LR3 will be represented as shown in FIG. 58.

[0237] FIG. 58 is a schematic diagram for explaining each part of the lumen region LR3 in the third embodiment. FIG. 58 shows the lumen region LR3, the first core wire CL31, and the branch point BP30. In the lumen region LR3, the thick parent branch located at the upper part is called the main trunk part, and the three small branches branching from the main trunk part located at the lower part are respectively called the first branch part, the second branch part, and the third branch part. Also, the third branch part is located between the first branch part and the second branch part, or the first branch part, the second branch part, and the third branch part branch in three-dimensionally different directions like a tripod. Here, in FIG. 58, the main trunk part represents the region extending upward from the branch point BP30, the first branch part represents the region extending from the branch point BP30 in the lower left direction, the second branch part represents the region extending from the branch point BP30 in the lower right direction, and the third branch part represents the region extending from the branch point BP30 in the downward direction. That is, it is assumed that the third branch part in FIG. 58 is located between the first branch part and the second branch part.

[0238] Note that the main body, the first branch, the second branch, and the third branch do not necessarily need to have their regions clearly distinguished in the inner cavity region LR3. That is, each of these parts is at least defined by the direction extending from the branch point BP30 to the four end points on the first core wire CL31. For example, starting from the branch point BP30, the extending direction to the main body may be defined as the first direction, the extending direction to the first branch may be defined as the second direction, the extending direction to the second branch may be defined as the third direction, and the extending direction to the third branch may be defined as the fourth direction. Also, these directions may be obtained by analysis or may be given in advance.

[0239] (Step ST310) After detecting the branch point of the first core wire in step ST30B, the processing circuit 110 sets four points on the first core wire at a predetermined distance from the branch point.

[0240] The predetermined distance in the third embodiment is based on, for example, (1) a fixed distance close to the branch point, (2) a sphere centered on the branch point, and (3) the size of the diameter of each part of the inner cavity region. Note that specific examples of the predetermined distance may be the same as those described in the first embodiment, so the description is omitted.

[0241] (Step ST320) After setting the four points on the first core wire, the processing circuit 110 sets the vectors from the branch point to the four points. Hereinafter, the setting of the four points on the first core wire and the vectors from the branch point to the four points will be described with reference to FIG. 59.

[0242] FIG. 59 is a schematic diagram for explaining the setting of four points on the first core wire and the vectors from the branch point to the four points in the third embodiment. In FIG. 59, with respect to FIG. 58, proximity points NP21, NP22, NP23, and NP24 as four points are added on the first core wire CL31. Further, in FIG. 59, a first vector vNP21 from the branch point BP30 to the proximity point NP21, a second vector vNP22 from the branch point BP30 to the proximity point NP22, a third vector vNP23 from the branch point BP30 to the proximity point NP23, and a fourth vector vNP24 from the branch point BP30 to the proximity point NP24 are shown.

[0243] According to FIG. 59, first, the processing circuit 110 sets four points (proximity points NP21, NP22, NP23, and NP24) on the first core wire CL31 at a predetermined distance from the branch point BP30. Specifically, the processing circuit 110 sets the proximity point NP21 on the main trunk part, the proximity point NP22 on the first branch part, the proximity point NP23 on the second branch part, and the proximity point NP24 on the third branch part on the first core wire CL31, respectively.

[0244] Next, the processing circuit 110 sets vectors (the first vector vNP21, the second vector vNP22, the third vector vNP23, and the fourth vector vNP24) from the branch point BP30 to the four points (proximity points NP21, NP22, NP23, and NP24).

[0245] (Step ST330) After setting the four vectors, the processing circuit 110 analyzes the branching directions of the three branch parts. After step ST330, the process proceeds to step ST40B in FIG. 53. These three branch parts are the first branch part, the second branch part, and the third branch part described above. Hereinafter, the analysis of the branching directions of the three branch parts will be specifically described.

[0246] First, the processing circuit 110 calculates the cross product vectors for all combinations of the vectors set for each of the three branch portions. Specifically, the processing circuit 110 calculates a cross product vector v2×3 which is the cross product of the second vector vNP22 and the third vector vNP23, a cross product vector v2×4 which is the cross product of the second vector vNP22 and the fourth vector vNP24, and a cross product vector v3×4 which is the cross product of the third vector vNP23 and the fourth vector vNP24, respectively.

[0247] Next, the processing circuit 110 calculates an angle θ2×3·2×4 formed by the cross product vector v2×3 and the cross product vector v2×4, an angle θ2×3·3×4 formed by the cross product vector v2×3 and the cross product vector v3×4, and an angle θ2×4·3×4 formed by the cross product vector v2×4 and the cross product vector v3×4, respectively.

[0248] When all of the angles θ2×3·2×4, θ2×3·3×4, and θ2×4·3×4 are approximately 0 degrees or approximately 180 degrees, all of the branch point BP30, the neighboring point NP22, the neighboring point NP23, and the neighboring point NP24 will be located on substantially the same plane. In this case, further, the processing circuit 110 compares the norms (vector lengths) of the calculated cross product vectors respectively, and selects the cross product vector having the maximum norm (for example, the cross product vector v2×4). Then, the processing circuit 110 selects a vector (for example, the fourth vector vNP24) that was not used for the calculation of the extracted cross product vector, and a neighboring point (for example, the neighboring point NP24) corresponding to that vector. As a result, the branch portion (the third branch portion) of the first core wire CL31 where the selected neighboring point (the neighboring point NP24) exists is sandwiched (substantially in the center) between the other two branch portions (the first branch portion and the second branch portion).

[0249] Also, when all of the angles θ2×3·2×4, θ2×3·3×4, and θ2×4·3×4 are not approximately 0 degrees or approximately 180 degrees, any one of the branch point BP30, the neighborhood point NP22, the neighborhood point NP23, and the neighborhood point NP24 will be located outside the same plane. In this case, the processing circuit 110 regards that the first branch portion, the second branch portion, and the third branch portion branch in three-dimensionally different directions like a tripod.

[0250] (Step ST40B) After the lumen analysis process, the processing circuit 110 executes the correction function 114. When the correction function 114 is executed, the processing circuit 110 generates a second core wire in which the position of the branch point in the first core wire is corrected. Hereinafter, the process of step ST40B will be referred to as the "core wire correction process". Hereinafter, a specific example of the core wire correction process in the third embodiment will be described with reference to the flowchart of FIG. 60.

[0251] FIG. 60 is a flowchart illustrating the core wire correction process (step ST40B) of the flowchart of FIG. 53. The flowchart of FIG. 60 transitions from step ST300 (or step ST330).

[0252] (Step ST410) After analyzing the branching directions of the three branch portions in step ST330, the processing circuit 110 determines whether the branch point and three points on the branch portion are substantially on the same plane. If it is determined that the branch point and the three points on the branch portion are substantially on the same plane, the process proceeds to step ST420. If it is determined that the branch point and the three points on the branch portion are not substantially on the same plane, the process proceeds to step ST460.

[0253] (Step ST420) After it is determined that the branch point and the three points on the branch portion are substantially on the same plane, the processing circuit 110 detects the third branch portion sandwiched between the first branch portion and the second branch portion.

[0254] (Step ST430) After detecting the third branch portion, the processing circuit 110 creates a first partial core wire connecting the branch start point and the first branch end point. Hereinafter, the process of step ST430 is referred to as "first partial core wire creation process". Note that the first partial core wire creation process in the third embodiment may be the same as that in the second embodiment, and thus the description thereof is omitted. Alternatively, the first partial core wire creation process in the third embodiment may be replaced with the branch start point setting process, the first branch end point setting process, and the first partial core wire creation process in the first embodiment.

[0255] (Step ST440) After creating the first partial core wire, the processing circuit 110 creates a second partial core wire connecting the branch start point and the second branch end point. Hereinafter, the process of step ST440 is referred to as "second partial core wire creation process". Note that the second partial core wire creation process in the third embodiment may be the same as that in the second embodiment, and thus the description thereof is omitted. Alternatively, the second partial core wire creation process in the third embodiment may be replaced with the second branch end point creation process and the second partial core wire creation process in the first embodiment.

[0256] After the above step ST440, the processing circuit 110 deletes the partial core wire from the branch point BP30 to the first branch end point BEP31 and the partial core wire from the branch point BP30 to the second branch end point BEP32 on the first core wire CL31. Then, the processing circuit 110 creates a first temporary core wire CL31' by adding the first partial core wire PCL31 from the branch start point BSP30 to the first branch end point and the second partial core wire PCL32 from the branch start point BSP30 to the second branch end point. Hereinafter, the first temporary core wire including the branch start point and a plurality of branch end points will be described with reference to FIG. 61.

[0257] FIG. 61 is a schematic diagram for explaining a first temporary core wire including a branch start point and a plurality of branch end points in the third embodiment. In FIG. 61, an inner cavity region LR3 and a first temporary core wire CL31' are shown. In the first temporary core wire CL31', a branch point BP30, a branch start point BSP30, a first branch end point BEP31, and a second branch end point BEP32 are shown. Note that the correction has not been made for the core wire that extends from the branch start point BSP30 through the branch point BP30 to the third branch portion in the first temporary core wire CL31'.

[0258] (Step ST450) After creating the second partial core wire, the processing circuit 110 creates a second partial core wire that connects the branch start point and the third branch end point. After step ST450, the process proceeds to step ST50B in FIG. 53. Hereinafter, the process of step ST450 will be referred to as the "third partial core wire creation process". Hereinafter, a specific example of the third partial core wire creation process will be described with reference to the flowchart of FIG. 62.

[0259] FIG. 62 is a flowchart illustrating the third partial core wire creation process of the flowchart of FIG. 60. The flowchart of FIG. 62 transitions from step ST440. Hereinafter, in the first temporary core wire CL31', the correction of the core wire that extends from the branch start point BSP30 through the branch point BP30 to the third branch portion will be described.

[0260] (Step ST4501) After creating the second partial core wire, the processing circuit 110 sets a plurality of neighboring points at different distances centered on the branch point. Hereinafter, the setting of the plurality of neighboring points will be described with reference to FIG. 63.

[0261] FIG. 63 is a schematic diagram for explaining the setting of a plurality of neighboring points in the third embodiment. In FIG. 63, with respect to FIG. 61, two neighboring points (neighboring point NP211 and neighboring point NP212) in the first direction and two neighboring points (neighboring point NP241 and neighboring point NP242) in the fourth direction are added on the first temporary core wire CL31' from the branch point BP30.

[0262] According to FIG. 63, first, the processing circuit 110 sets the vicinity points NP211 and NP241 located at a position of a straight-line distance r not along the core wire around the branch point BP30. Next, the processing circuit 110 sets the vicinity points NP212 and NP242 located at a position of a straight-line distance 3r not along the core wire around the branch point BP30. Note that it is desirable that the straight-line distance 3r is shorter than the straight-line distance from the branch point BP30 to the branch start point BPS30. From this, the processing circuit 110 may set the vicinity points NP212 and NP242 first and then set the vicinity points NP211 and NP241.

[0263] (Step ST4502) After setting a plurality of vicinity points, the processing circuit 110 creates a curve so as to pass through the set plurality of vicinity points using a known interpolation technique. Hereinafter, the creation of a curve passing through a plurality of vicinity points will be described with reference to FIG. 64.

[0264] FIG. 64 is a schematic diagram for explaining the creation of a curve passing through a plurality of vicinity points in the third embodiment. FIG. 64 shows the lumen region LR3 and the first virtual core wire CL31' passing through the inside of the lumen region LR3. Further, a curve PCL33 connecting at least the vicinity point NP212 and the vicinity point NP242 is shown on the second core wire CL32.

[0265] According to FIG. 64, the processing circuit 110 creates the curve PCL33 by performing curve interpolation so as to pass through a plurality of vicinity points (vicinity point NP212, vicinity point NP211, vicinity point NP241, and vicinity point NP242). For curve interpolation, an interpolation method for creating a B-spline curve or the like can be used.

[0266] (Step ST4503) After creating the curve, the processing circuit 110 sets the center of the two vicinity points closest to the branch point as the branch center point. Hereinafter, the setting of the branch center point will be described with reference to FIG. 65.

[0267] FIG. 65 is a schematic diagram for explaining the setting of the branch center point in the third embodiment. In FIG. 65, with respect to FIG. 64, a branch center point BMP30 is added at an intermediate position between the nearby point NP211 and the nearby point NP241 on the curve PCL33.

[0268] According to FIG. 65, the processing circuit 110 sets the center of the two nearest nearby points (the nearby point NP211 and the nearby point NP241) to the branch center point BMP30.

[0269] (Step ST4504) After setting the temporary branch point, the processing circuit 110 sets the third branch end point based on the branch start point and the branch center point. Specifically, the processing circuit 110 sets the third branch end point at a position in the opposite direction from the branch start point by a distance equal to the distance from the branch center point to the branch start point, with the branch center point as the center. Hereinafter, the setting of the third branch end point will be described with reference to FIG. 66.

[0270] FIG. 66 is a schematic diagram for explaining the setting of the third branch end point in the third embodiment. In FIG. 66, with respect to FIG. 65, a third branch end point BEP33 is added on the curve PCL33.

[0271] According to FIG. 66, the processing circuit 110 calculates the distance from the branch center point BMP30 to the branch start point BSP30, and sets the third branch end point BEP33 at a position separated by the calculated distance in the opposite direction from the branch start point BSP30 from the branch center point BMP30.

[0272] (Step ST4505) After setting the third branch end point, the processing circuit 110 sets the curve from the branch start point to the third branch end point as the third partial core wire. Specifically, the processing circuit 110 expands the curve PCL33 created in step ST4502, and sets the expanded curve from the branch start point including the curve PCL33 to the third branch end point as the third partial core wire. After step ST4505, the process proceeds to step ST50B in FIG. 53.

[0273] (Step ST460) After it is determined in step ST410 that the branch point and the three points on the branch portion are not on substantially the same plane, the processing circuit 110 executes step ST40 or step ST40A for each of the three branch portions. Specifically, the processing circuit 110 generates a second core wire by performing core wire correction processing in the first embodiment or the second embodiment for the first branch portion, the second branch portion, and the third branch portion. After step ST460, the process proceeds to step ST50B in FIG. 53.

[0274] (Step ST50B) After creating the second core wire, the processing circuit 110 executes the display control function 115. When the display control function 115 is executed, the processing circuit 110 displays the second core wire including the branch start point and the plurality of branch end points. Hereinafter, the display of the second core wire including the branch start point and the plurality of branch end points will be described with reference to FIG. 67.

[0275] FIG. 67 is a schematic diagram for explaining the display of the second core wire including the branch start point and the plurality of branch end points in the third embodiment. In FIG. 67, the lumen region LR3 and the second core wire CL32 passing through the inside of the lumen region LR3 are shown. Also, on the second core wire CL32, a branch start point BSP30, a first partial core wire PCL31, a first branch end point BEP31, a second partial core wire PCL32, a second branch end point BEP32, a third partial core wire PCL33, and a third branch end point BEP33 are shown.

[0276] Note that in FIG. 67, the processing circuit 110 displays the second core wire CL32 three-dimensionally, but it is not limited to this. For example, it may be displayed two-dimensionally as in the first embodiment and the second embodiment. That is, the processing circuit 110 may display the second core wire CL32 in an arbitrary cross section of the lumen region LR3.

[0277] According to FIG. 67, the processing circuit 110 displays a second core line CL32 including a branch start point BSP30, a first branch end point BEP31, a second branch end point BEP32, and a third branch end point BEP33. Incidentally, the processing circuit 110 may display a first core line CL31 including a branch point BP30 together with the second core line CL32. By displaying both the first core line CL31 and the second core line CL32, the user can confirm the states of the core line before and after correction. Further, the processing circuit 110 may set and display, as a plurality of branch center points on the second core line, the center points from the branch start point BSP30 to each of the plurality of branch end points.

[0278] As described above, the medical image processing apparatus according to the third embodiment sets four points on the first core line in the extending directions of the main trunk portion, the first branch portion, the second branch portion, and the third branch portion starting from the branch point, which are at a predetermined distance from the branch point, for a tubular structure that branches into three. When the branch point and the three points set on the first branch portion, the second branch portion, and the third branch portion are substantially on the same plane, the third branch portion sandwiched between the first branch portion and the second branch portion is detected, and a plurality of control points are set on the first core line from the branch start point to the third branch end point, and the second core line is generated by performing curve interpolation on the plurality of control points.

[0279] Further, when the branch point and the three points set on the first branch portion, the second branch portion, and the third branch portion are not substantially on the same plane, the medical image processing apparatus according to the third embodiment sets a plurality of control points on the first core line for each of the first branch portion, the second branch portion, and the third branch portion, and generates the second core line based on the branch point, the plurality of control points, the lumen region, the branch start point, the first branch end point, the second branch end point, and the third branch end point.

[0280] Therefore, the medical image processing apparatus according to the third embodiment can correct the core line in the vicinity of the branch portion of the tubular structure even if the tubular structure branches into three.

[0281] (Fourth Embodiment) In the third embodiment, as a specific example, medical image processing for a tubular structure having one branch point and branching into three branches was described. On the other hand, in the fourth embodiment, as a specific example, medical image processing for a tubular structure having two branch points and branching into three branches will be described.

[0282] The medical image processing apparatus according to the fourth embodiment has substantially the same configuration as the medical image processing apparatus according to each of the foregoing embodiments. Therefore, the description of the configuration of the medical image processing apparatus according to the fourth embodiment is omitted.

[0283] FIG. 68 is a flowchart for explaining the operation of the processing circuit 110 that executes medical image processing in the fourth embodiment. In the medical image processing in the fourth embodiment, a process of analyzing branch points (branch point analysis process) is added to the medical image processing in the third embodiment. The medical image processing shown in FIG. 68 starts according to a user's instruction.

[0284] (Step ST10C) When the medical image processing starts, the processing circuit 110 executes the acquisition function 112. When the acquisition function 112 is executed, the processing circuit 110 acquires medical image data. Specifically, the processing circuit 110 acquires, for example, medical image data stored in the memory 120. Note that the external shape of the medical image data in the fourth embodiment is substantially the same as the medical image data in FIG. 54 described in the third embodiment. That is, the medical image data according to the fourth embodiment is data of a blood vessel that branches from a parent branch into three small branches.

[0285] (Step ST20C) After acquiring the medical image data, the processing circuit 110 executes the extraction function 113. When the extraction function 113 is executed, the processing circuit 110 extracts the lumen region and the first centerline. Specifically, the processing circuit 110 extracts the lumen region from the medical image data, and extracts the first centerline by performing thinning processing on the lumen region. Hereinafter, specific examples of the lumen region and the first centerline in the fourth embodiment will be described with reference to FIG. 69.

[0286] FIG. 69 is a schematic diagram showing a specific example of the lumen region LR4 and the first core wire CL41 in the fourth embodiment. In FIG. 69, the lumen region LR4 and the first core wire CL41 passing through the inside of the lumen region LR4 are shown.

[0287] According to FIG. 69, the processing circuit 110 extracts the lumen region LR4 from medical image data MID4 (not shown). Then, the processing circuit 110 extracts the first core wire CL41 by performing a thinning process on the lumen region LR4. It is assumed that the first core wire CL41 has two branch points.

[0288] (Step ST30C) After extracting the lumen region and the first core wire, the processing circuit 110 detects the branch points of the first core wire by the extraction function 113. Specifically, the processing circuit 110 detects the branch points by tracking the core wire position from a plurality of end points on the first core wire. Hereinafter, the detection of the branch points in the fourth embodiment will be described with reference to FIG. 70.

[0289] FIG. 70 is a schematic diagram for explaining the detection of the branch points (the first branch point BP41 and the second branch point BP42) of the first core wire CL41 in the fourth embodiment. In FIG. 70, the lumen region LR4, the first core wire CL41, and the first branch point BP41 and the second branch point BP42 on the first core wire CL41 are shown.

[0290] According to FIG. 70, the processing circuit 110 detects the first branch point BP41 and the second branch point BP42 by tracking the core wire position from four end points on the first core wire CL41. At this time, the processing circuit 110 tracks the core wire position from the end point of the main trunk, and sets the first branching point as the first branch point BP41.

[0291] (Step ST500) After detecting the branch points of the first core wire, the processing circuit 110 executes a branch point analysis process. Hereinafter, a specific example of the branch point analysis process will be described with reference to the flowchart of FIG. 71.

[0292] FIG. 71 is a flowchart illustrating the branch point analysis process of the flowchart of FIG. 68. The flowchart of FIG. 71 transitions from step ST30C. Hereinafter, the vicinity region NR near the branch point in FIG. 70 will be described with attention.

[0293] (Step ST510) After detecting the branch point of the first core wire, the processing circuit 110 sets the center of the two branch points as a provisional branch point. Hereinafter, the setting of the provisional branch point will be described with reference to FIG. 72.

[0294] FIG. 72 is a schematic diagram for explaining the setting of the provisional branch point in the fourth embodiment. In FIG. 72, in the vicinity region NR of FIG. 70, the first core wire CL41, the first branch point BP41 and the second branch point BP42 on the first core wire CL41, and further the provisional branch point PBP40 are shown.

[0295] According to FIG. 72, the processing circuit 110 sets the center of the two branch points (the first branch point BP41 and the second branch point BP42) as the provisional branch point PBP40. This provisional branch point PBP40 is set on the first core wire CL41 at the intermediate point between the first branch point BP41 and the second branch point BP42.

[0296] (Step ST520) After setting the provisional branch point, the processing circuit 110 sets a plurality of neighboring points centered on the provisional branch point. Hereinafter, the setting of the plurality of neighboring points will be described with reference to FIG. 73.

[0297] FIG. 73 is a schematic diagram for explaining the setting of a plurality of neighboring points in the fourth embodiment. In FIG. 73, with respect to FIG. 72, neighboring points NP41 in the first direction from the first branch point BP41, neighboring points NP42 in the second direction, neighboring points NP43 in the third direction from the second branch point BP42, and neighboring points NP44 in the fourth direction are added on the first core wire CL41. These plurality of neighboring points are set at the positions where the sphere with a radius of distance δ centered on the provisional branch point PBP40 intersects the first core wire CL41.

[0298] According to FIG. 73, first, the processing circuit 110 sets a sphere centered on the temporary branch point PBP40 with a radius of distance δ. Next, the processing circuit 110 sets a plurality of neighboring points (neighboring point NP41, neighboring point NP42, neighboring point NP43, and neighboring point NP44) at positions where the set sphere intersects with the first core wire CL41. It is desirable that the distance δ is longer than the straight-line distance from the temporary branch point PBP40 to the first branch point BP41 or the second branch point BP42. If it is shorter than this straight-line distance, neighboring points will be set on the side of the temporary branch point PBP40 with respect to the second branch point BP42, which is inconvenient. Specifically, the distance δ is set, for example, to a distance that is twice the straight-line distance (i.e., the distance not along the core wire) from the temporary branch point PBP40 to the first branch point BP41 or the second branch point BP42. Alternatively, the distance δ may be set to the straight-line distance (i.e., the distance not along the core wire) from the first branch point BP41 to the second branch point BP42.

[0299] (Step ST530) After setting a plurality of neighboring points, the processing circuit 110 deletes the partial core wires extending from the plurality of neighboring points in the direction of the branch point or the temporary branch point. Hereinafter, the deletion of the partial core wires will be described with reference to FIG. 74.

[0300] FIG. 74 is a schematic diagram for explaining the deletion of the partial core wires in the fourth embodiment. In FIG. 74, compared with FIG. 73, the line segment sNP41 from the neighboring point NP41 to the temporary branch point PBP40, the line segment sNP42 from the neighboring point NP42 to the first branch point BP41, the line segment sNP43 from the neighboring point NP43 to the second branch point BP42, and the line segment sNP44 from the neighboring point NP44 to the temporary branch point PBP40 are deleted.

[0301] According to FIG. 74, the processing circuit 110 deletes the line segments sNP41, sNP42, sNP43, and sNP44, which are parts (partial core wires) of the first core wire CL41.

[0302] (Step ST540) After deleting the partial core wires, the processing circuit 110 creates a plurality of temporary partial core wires that connect the temporary branch point and the plurality of neighboring points respectively.

[0303] (Step ST550) After creating the temporary partial core wires, the processing circuit 110 sets a first temporary core wire that branches from the temporary branch point. After step ST550, the process proceeds to step ST300C in FIG. 68. Hereinafter, the creation of a plurality of temporary partial core wires and the setting of the first temporary core wire will be described with reference to FIG. 75.

[0304] FIG. 75 is a schematic diagram for explaining the creation of a plurality of temporary partial core wires and the setting of the first temporary core wire in the fourth embodiment. In FIG. 75, compared with FIG. 74, a line segment sNNP41 from the vicinity point NP41 to the temporary branch point PBP40, a line segment sNNP42 from the vicinity point NP42 to the temporary branch point PBP40, a line segment sNNP43 from the vicinity point NP43 to the temporary branch point PBP40, and a line segment sNNP44 from the vicinity point NP44 to the temporary branch point PBP40 are added. Further, due to the addition of these line segments, instead of the first core wire CL41, a first temporary core wire CL41' that branches from the temporary branch point PBP40 is set.

[0305] According to FIG. 75, first, the processing circuit 110 creates the line segments sNNP41, sNNP42, sNNP43, and sNNP44, and uses each of them as a temporary partial core wire. Next, the processing circuit 110 sets a first temporary core wire CL41' that branches from the temporary branch point PBP40.

[0306] Note that before executing the above-described lumen analysis process, the processing circuit 110 measures the distance between the first branch point BP41 and the second branch point BP42, and if the measured distance is equal to or greater than a predetermined distance (that is, when the first branch point BP41 and the second branch point BP42 are not in the vicinity), the branch point analysis process may not be executed. When the branch point analysis process is not executed, the processing circuit 110 may also not execute the subsequent lumen analysis process, and may perform a core wire correction process for each of the first branch point BP41 and the second branch point BP42.

[0307] (Step ST300C) After the branch point analysis process, the processing circuit 110 executes a lumen analysis process. In the fourth embodiment, the processing circuit 110 executes a lumen analysis process on the first provisional core wire set by the branch point analysis process. Note that the lumen analysis process is the same as that in the third embodiment, and thus the description thereof is omitted.

[0308] (Step ST40C) After the lumen analysis process, the processing circuit 110 executes a correction function 114. When the correction function 114 is executed, the processing circuit 110 sets the first provisional core wire as the first core wire, and generates a second core wire in which the position of the branch point in the first core wire is corrected. Hereinafter, the process of step ST40C is referred to as a "core wire correction process". Note that the core wire correction process is the same as that in the third embodiment, and thus the description thereof is omitted.

[0309] (Step ST50C) After creating the second core wire, the processing circuit 110 executes a display control function 115. When the display control function 115 is executed, the processing circuit 110 displays the second core wire including a branch start point and a plurality of branch end points. Note that the display of the second core wire is the same as that in the third embodiment, and thus the description thereof is omitted.

[0310] As described above, for a tubular structure that branches into three, when there are two branch points in the first core wire and the distance between the two branch points is within a predetermined distance in the fourth embodiment, a provisional branch point that is in the middle of the two branch points is set on the first core wire, a provisional core wire obtained by correcting the first core wire with the provisional branch point is generated, and a second core wire in which the position of the provisional branch point in the provisional core wire is corrected is generated based on the information of the lumen region and the information of the provisional core wire.

[0311] Therefore, the medical image processing apparatus according to the fourth embodiment can correct the core wire in the vicinity of the branch portion of the tubular structure even when a plurality of branch points are respectively in the vicinity.

[0312] (Application Examples of Each Embodiment) In each of the above embodiments, as a specific example, the analysis was based on blood vessels having a branch portion in a living body, but it is not limited thereto. For example, the medical image processing apparatus according to each embodiment may analyze a general tubular structure including a branch portion such as a bronchus instead of a blood vessel.

[0313] Also, in each of the above embodiments, the analysis is performed using three-dimensional medical image data, but it is not limited thereto. For example, instead of three-dimensional medical image data, two-dimensional medical image data may be analyzed. The two-dimensional medical image data is, for example, MIP (Maximum Intensity Projection) image data generated when blood vessels are imaged by an X-ray fluoroscopic diagnostic apparatus (X-ray angiography) for blood vessel fluoroscopy. Different from the above embodiments, for the processing of one cross-section, although it is simple, it is useful to correct the core line sparsely extracted by the thinning process.

[0314] Also, when the core line is corrected according to each of the above embodiments, the corrected core line (second core line) is extended from one feature point (branch point) defined on the conventional core line (first core line) to a plurality of feature points (branch start point and a plurality of branch end points). Thus, since the feature points are extended and the core line position is also updated, the medical image processing apparatus according to each embodiment may update the screen display using a plurality of feature points and the core line position and update the value by analysis (measurement).

[0315] Specifically, when the core line is corrected, the multi-cross-section image orthogonal to the core line may be automatically updated in the medical image processing apparatus according to each embodiment. This multi-cross-section image is a cross-section at a position orthogonal to the core line at regular intervals along the core line. In a tubular structure, the cross-section may be sequentially changed and observed by changing the core line position with the center of the cross-section where the core line is displayed on the screen.

[0316] In addition, when the medical image processing apparatus according to each embodiment has a function of measuring the length of a section from a specific position to a branch point, it can measure the length of a section from the specific position to a branch start point or a branch end point. Further, when measuring the length of a branch portion, the medical image processing apparatus according to each embodiment can measure the length from a corrected branch start point instead of the length from a conventional branch point. From these facts, the medical image processing apparatus according to each embodiment can obtain a value different from the conventional length value.

[0317] In addition, when the medical image processing apparatus according to each embodiment has a function of measuring various measured values at each position in the lumen region and graphically displaying the length direction along the core line position as the X-axis of the graph and the various values as the Y-axis, the medical image processing apparatus according to each embodiment may be automatically updated from a graph based on the core line before correction to a graph based on the core line after correction as the core line is corrected. Note that the above various measured values include the diameter of the lumen region (e.g., blood vessel diameter), the cross-sectional area, and fluid parameters (e.g., blood pressure, blood flow rate, and fractional flow reserve ratio (FFR)) when fluid analysis is performed with the lumen region as a flow path.

[0318] In addition, when the lumen region is a blood vessel, analysis of the blood vessel (particularly measurement of the stenosis rate) is often performed in the coronary artery and the cerebral artery. From this fact, the medical image processing apparatus according to each embodiment is also effective for correcting the core line of the branch portion of the coronary artery and the cerebral artery as a preprocessing for blood vessel analysis.

[0319] According to at least one of the embodiments described above, the core line in the vicinity of the branch portion of the tubular structure can be corrected.

[0320] Note that the term "processor" used in the above description means, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), or a circuit such as an application specific integrated circuit (ASIC) or a programmable logic device (for example, a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), and a field programmable gate array (FPGA)). When the processor is, for example, a CPU, the processor realizes its function by reading and executing a program stored in a storage circuit. On the other hand, when the processor is, for example, an ASIC, instead of storing the program in the storage circuit, the function is directly incorporated as a logic circuit in the circuit of the processor. Note that each processor of the present embodiment is not limited to being configured as a single circuit for each processor, and a plurality of independent circuits may be combined to form one processor to realize its function. Further, a plurality of components in the figure may be integrated into one processor to realize its function.

[0321] In addition, each function according to the embodiment can also be realized by installing a program for executing the above processing in a computer such as a workstation and expanding them in a memory. At this time, the program that can cause the computer to execute the above method can also be stored and distributed in a storage medium such as a magnetic disk (such as a hard disk), an optical disk (such as a CD-ROM, a DVD), or a semiconductor memory.

[0322] Although some embodiments have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, changes, and combinations of embodiments can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, as well as in the invention described in the claims and the equivalent scope thereof.

Explanation of Reference Numerals

[0323] 10, 32, 33, 34, 200, 420, 430, 440 Cross Sections 11, 31, 210, 410 Core Wires 12, 220 Boundary Lines 20, 300 Extended Images 30, 400 Lumen Regions 41, 42, 43, 510, 520, 530 Cross-Sectional Images 100 Medical Image Processing Apparatus 110 Processing Circuit 111 System Control Function 112 Acquisition Function 113 Extraction Function 114 Correction Function 115 Display Control Function 120 Memory 130 Display 140 Input Interface 150 Communication Interface NW Network MID1, MID3 Medical Image Data LR1, LR2, LR3, LR4 Lumen Regions CL11, CL21, CL31, CL41 First Core Wires CL31’, CL41’ First Temporary Core Wires CL12, CL22 Second Core Wires BP10, BP20, BP30 Branch Points BP41 First Branch Point BP42 Second Branch Point PBP40 Temporary Branch Point BSP10, BSP20, BSP30 Branch start points BEP11, BEP21, BEP31 First branch end points BEP12, BEP22, BEP32 Second branch end points BEP33 Third branch end point PCL11, PCL21, PCL31 First partial core wires PCL12, PCL22, PCL32 Second partial core wires PCL33 Third partial core wire BMP11 First branch center point BMP12 Second branch center point

Claims

1. An extraction unit that extracts a lumen region, which is an internal region of the tubular structure, from medical image data including the tubular structure having a branch portion in vivo, and extracts a first core line by performing a thinning process on the lumen region; A correction unit that generates a second core line with the position of a branch point on the first core line corrected based on the information of the lumen region and the information of the first core line; A medical image processing apparatus comprising the above.

2. The information of the lumen region includes position information of the lumen region and information regarding a branching direction of the branch portion; The information of the first core line includes position information of the first core line. The medical image processing apparatus according to Claim 1.

3. The lumen region has a main trunk portion and a plurality of branch portions branching from the main trunk portion; The correction unit: Sets a branch start point, which is a new branch point, on the first core line by moving the branch point in the extending direction of the main trunk portion starting from the branch point; Generates the second core line branching from the branch start point. The medical image processing apparatus according to Claim 2.

4. The correction unit: Sets a plurality of branch end points on the first core line in the extending direction of each of the plurality of branch portions starting from the branch point; Generates the second core line branching from the branch start point to each of the plurality of branch end points. The medical image processing apparatus according to Claim 3.

5. The correction unit generates the second core line using the distance from the branch point to a first point on the boundary of the lumen region, the distance from the branch start point to a second point on the boundary of the lumen region different from the first point, and the distances from the plurality of branch end points to a plurality of points respectively on the boundary of the lumen region different from the first point and the second point. The medical image processing apparatus according to claim 4.

6. The correction unit sets a plurality of control points on the first core wire, sets the branch start point and the plurality of branch end points based on the branch point, the plurality of control points, and the lumen region, and generates the second core wire based on the branch point, the plurality of control points, the lumen region, the branch start point, and the plurality of branch end points. The medical image processing apparatus according to claim 5.

7. The correction unit sets points on the first core wire at a predetermined distance from the branch point as the branch start point and the plurality of branch end points, respectively, sets a plurality of control points on the first core wire based on the branch point, the branch start point, and the plurality of branch end points, and generates the second core wire based on the branch point, the plurality of control points, the lumen region, the branch start point, and the plurality of branch end points. The medical image processing apparatus according to claim 5.

8. The plurality of branch portions include a first branch portion and a second branch portion, the plurality of branch end points include a first branch end point corresponding to the first branch portion and a second branch end point corresponding to the second branch portion, and the correction unit generates the second core wire that branches from the branch start point to the first branch end point and the second branch end point, respectively. The medical image processing apparatus according to claim 4.

9. The correction unit sets control points on the first core wire at every predetermined distance from the branch point for each of a first direction that is the extending direction of the main trunk portion starting from the branch point, a second direction that is the extending direction of the first branch portion starting from the branch point, and a third direction that is the extending direction of the second branch portion starting from the branch point. Set the control points that satisfy the predetermined conditions as the branch start point for the first direction, the first branch end point for the second direction, and the second branch end point for the third direction. The medical image processing apparatus according to claim 8.

10. The predetermined condition is that the internal angle between the line segment connecting the control point and the boundary point of the lumen region and the line segment connecting the control point and another control point on the first core wire at a predetermined distance in the direction opposite to the branch point from the control point is approximately 90 degrees. The medical image processing apparatus according to claim 9.

11. The correction unit sets three points on the first core wire separated by a predetermined distance from the branch point as the branch start point, the first branch end point, and the second branch end point, respectively. The medical image processing apparatus according to claim 8.

12. The predetermined distance is based on the diameters of the main trunk portion, the first branch portion, and the second branch portion, respectively. The medical image processing apparatus according to claim 10 or claim 11.

13. The predetermined distance is based on the size of a predetermined geometric shape centered on the branch point. The medical image processing apparatus according to claim 10 or claim 11.

14. The predetermined distance is based on the distribution of the predetermined geometric shape in contact with the boundary of the lumen region. The medical image processing apparatus according to claim 13.

15. The plurality of branch portions includes a first branch portion, a second branch portion, and a third branch portion. The plurality of branch end points includes a first branch end point corresponding to the first branch portion, a second branch end point corresponding to the second branch portion, and a third branch end point corresponding to the third branch portion. The correction unit generates the second core wire that branches from the branch start point to the first branch end point, the second branch end point, and the third branch end point, respectively. The medical image processing apparatus according to claim 4.

16. The correction unit sets four points on the first core wire in the extending directions of the main trunk portion, the first branch portion, the second branch portion, and the third branch portion starting from the branch point, which are at a predetermined distance from the branch point. When the branch point and the three points set on the first branch portion, the second branch portion, and the third branch portion are substantially on the same plane, the third branch portion sandwiched between the first branch portion and the second branch portion is detected. sets a plurality of control points on the first core wire from the branch start point to the third branch end point. generates the second core wire by performing curve interpolation on the plurality of control points. The medical image processing apparatus according to claim 15.

17. The correction unit sets four points on the first core wire in the extending directions of the main trunk portion, the first branch portion, the second branch portion, and the third branch portion starting from the branch point, which are at a predetermined distance from the branch point. When the branch point and the three points set on the first branch portion, the second branch portion, and the third branch portion are not substantially on the same plane, a plurality of control points are set on the first core wire for each of the first branch portion, the second branch portion, and the third branch portion. generates the second core wire based on the branch point, the plurality of control points, the lumen region, the branch start point, the first branch end point, the second branch end point, and the third branch end point. The medical image processing apparatus according to claim 15.

18. In the first core wire, when there are two branch points including the branch point The correction unit When the distance between the two branch points is within a predetermined distance, a virtual branch point that is the middle of the two branch points is set on the first core wire, A virtual core wire obtained by correcting the first core wire with the virtual branch point is generated, Based on the information of the inner cavity region and the information of the virtual core wire, a second core wire with the position of the virtual branch point on the virtual core wire corrected is generated. The medical image processing apparatus according to claim 1.

19. A display control unit that displays the branch start point, the plurality of branch end points, and the second core wire is further provided. The medical image processing apparatus according to claim 4.

20. The correction unit sets center points on partial core wires from the branch start point to each of the plurality of branch end points as a plurality of branch center points on the second core wire, The display control unit further displays the plurality of branch center points. The medical image processing apparatus according to claim 19.

21. A computer extracts an inner cavity region, which is an internal region of the tubular structure, from medical image data including the tubular structure having a branch portion in a living body, and extracts a first core wire by performing a thinning process on the inner cavity region, generates a second core wire with the position of the branch point on the first core wire corrected based on the information of the inner cavity region and the information of the first core wire A medical image processing method comprising:

22. A computer means for extracting an inner cavity region, which is an internal region of the tubular structure, from medical image data including the tubular structure having a branch portion in a living body, and extracting a first core wire by performing a thinning process on the inner cavity region; means for generating a second core wire with the position of the branch point on the first core wire corrected based on the information of the inner cavity region and the information of the first core wire A medical image processing program that functions as

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