JP2006122663A - Image processing apparatus and image processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processing apparatus capable of generating a more useful cross-sectional image with less work burden in the case of generating the cross-sectional image of a curved observation target. <P>SOLUTION: A plurality of position data are inputted, which indicate the position of the observation target defined in a three-dimensional space, on its three-dimensional image, which is viewed from a predetermined view point along a predetermined line-of-sight direction. A curved cross section in the line-of-sight direction is computed from the plurality of position data and line-of-sight data including the predetermined view point and the predetermined line-of-sight direction. A projection image is generated by projecting the three-dimensional image on the computed curved cross-section onto a projection surface along the line-of-sight direction. The projection image is then displayed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image processing method, an image processing apparatus, and an image processing method capable of providing an image with which a curved cross-sectional shape of an observation target can be easily grasped.

  An image processing apparatus used in the medical image field in recent years is used in combination with medical imaging equipment such as an ultrasonic diagnostic apparatus, an X-ray CT scan, and a magnetic resonance imaging apparatus, and is widely used in many hospitals and examination institutions. It's being used. This image processing apparatus is capable of providing various images useful as clinical information as the speed of image processing increases and the resolution is improved. For example, in a simulation before surgery, blood vessel running, gastrointestinal tumor, plaque (spots) ), And imaging of the digestive tract cavity when examining the cause of stenosis, etc.

  Conventionally, in such an image processing apparatus, a curved multi-planar reformatting (Curved MRP: hereinafter abbreviated as “C-MPR”) is a method for displaying a cross section of an object in an easy-to-see manner from a three-dimensional image including a bent observation object. ) Is known. For example, (1) a polygonal line is set on a screen on which the entire three-dimensional image is displayed. (2) A cross section (C-MPR cross section) including a polygonal line set perpendicular to the screen is configured. (3) The pixel value on the cross section is displayed as it is as a two-dimensional image. It is executed following these steps.

  FIG. 6 is a diagram for explaining a C-MPR image (an image generated by C-MPR). In the figure, the polygonal line defining the C-MPR section is composed of four straight lines a, b, c and d. A C-MPR image is generated by displaying pixel values on a C-MPR cross section composed of four planes each including a broken line and perpendicular to the screen as they are. Therefore, C-MPR is a method of displaying pixel values that are not on a plane as a whole on a single plane, and according to this method, an image on a curved surface composed of a plane can be observed at one time. it can.

  Similarly, another method is also known in which pixel values that are not on a plane as a whole are displayed side by side on one plane. For example, (1) a broken line is displayed on a screen on which an entire three-dimensional image is displayed. Set. (2) A cross section (C-PC cross section) including a polygonal line set perpendicular to the screen is formed. (3) Only the pixel values on the cross section are projected and displayed on the projection plane in consideration of the viewpoint. It is executed following these steps. Here, this display method is referred to as Curvd Plane Cut (C-PC).

  FIG. 7 is an explanatory diagram of a C-PC image. In the figure, the right part shows a C-PC image, and the display shows the shape of the C-PC cross section. It is also possible to rotate the entire C-PC cross section and view from a different viewpoint.

  However, the conventional cross-sectional display method has the following problems, for example.

  First, since the C-MPR is an image obtained by developing a curved surface into a plane, the shape of an object to be observed cannot be grasped. For example, in medical image diagnosis, a torsional observation object such as a blood vessel is seen, but a curved surface cannot always be specified so that the bending condition of the entire observation object can be understood, so it is possible to grasp the bending condition of the entire observation object. There are things you can't do.

  Further, as is clear from the description of the C-MPR image described above, the observer views the C-MPR image from a direction different from the direction in which the 3D image was viewed when setting the C-MPR cross section. Become. As an observer, it is natural to view the cross section of the observation object from the same direction as the direction in which the three-dimensional image is viewed at that time. However, this requirement cannot be satisfied with C-MPR images.

  Furthermore, when it is desired to observe the observation object from a different direction after displaying the C-MPR image once, another C-MPR section must be set. Since this is a troublesome work, it places a heavy work burden on the observer. In an actual medical field, there is a demand for observing an observation object including a cross section of a blood vessel from various directions. Therefore, in order to satisfy this, the setting of the C-MPR section must be repeated many times, which is not realistic.

  Note that in a C-PC image, an image on a curved surface composed of a plane is displayed without being developed on a plane, and therefore it can be said that it is slightly better than C-MPR for grasping the shape of an observation object. However, since the method of specifying a curved surface is the same as that of C-MPR, there is a limit to grasping the entire shape.

  In addition, it is possible to observe from different directions by rotating the entire C-PC cross section. However, the C-PC cross section itself is the same, and the same data can only be viewed from different directions. Therefore, the request to view the cross section of the observation object from the same direction as the direction in which the three-dimensional image is viewed at that time cannot be satisfied even by the C-PC image.

  Furthermore, when it is desired to observe the observation object from a different direction after displaying the C-PC image once, another C-PC cross section must be set as in the case of C-MPR. Therefore, the observer has to repeat the setting of the C-PC cross section many times, which is not realistic.

In addition, as a well-known document relevant to this application, there exist the following, for example.
Japanese Patent Laid-Open No. 11-318884

  The present invention has been made in view of the above circumstances, and an image processing apparatus and an image processing method capable of generating a more useful cross-sectional image with a small work load when generating a cross-sectional image of a bent observation object. The purpose is to provide.

  In order to achieve the above object, the present invention takes the following measures.

  The invention according to claim 1 includes a position data specifying unit for specifying a plurality of position data indicating positions of the observation object on the input three-dimensional image data of the observation object, and the plurality of position data. A curved section calculation unit for calculating a first curved section in the line-of-sight direction from the line-of-sight data including the desired line-of-sight direction, and the three-dimensional image data or the first curved section on the first curved section. A projection image generation unit that generates a projection image by projecting three-dimensional image data relating to a region with reference to the projection plane along the line-of-sight direction, and a display unit that displays the projection image. An image processing apparatus characterized by the above.

  The invention according to claim 11 is an acquisition unit for acquiring three-dimensional image data of an observation object, and a position data specifying unit for specifying a plurality of position data indicating the position of the observation object on the three-dimensional image data. A curved section calculation unit for calculating a first curved section in the line-of-sight direction from the plurality of position data and line-of-sight data including a desired line-of-sight direction, and the three-dimensional image on the first curved section A projection image generation unit that generates a projection image by projecting data or three-dimensional image data relating to a region based on the first curved section onto the projection plane along the line-of-sight direction, and displaying the projection image A medical image diagnostic apparatus, comprising: a display unit.

  The invention according to claim 21 specifies a plurality of position data indicating the position of the observation object on the input three-dimensional image data of the observation object, and the plurality of position data and a desired line-of-sight direction. The first curved section in the line-of-sight direction is calculated from the line-of-sight data including the three-dimensional image data on the first curved section or the region based on the first curved section. Is projected onto a projection plane along the line-of-sight direction to generate a projected image and display the projected image.

  As described above, according to the present invention, it is possible to realize an image processing apparatus and an image processing method capable of generating a more useful cross-sectional image with a small work load when generating a cross-sectional image of a bent observation object.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, components having substantially the same function and configuration are denoted by the same reference numerals, and redundant description will be given only when necessary.

  Note that the image processing apparatus according to the present embodiment is assumed to be a single medical workstation that develops a dedicated program on a working memory and executes image processing to be described later, for example. However, the present invention is not limited to this, and may be an image processing apparatus built in various modalities such as a medical image dedicated viewer, an X-ray computed tomography apparatus, an ultrasonic diagnostic apparatus, and a magnetic resonance imaging apparatus.

  In the present embodiment, the three-dimensional image means not the displayed image but three-dimensional image data to be displayed. This three-dimensional image is defined on a real space (three-dimensional image space or volume space), and is sometimes referred to as volume data.

  FIG. 1 is a block diagram of an image processing apparatus 10 according to this embodiment. As shown in FIG. 1, the image processing apparatus 10 includes a control unit 11, a main storage unit 13, an external storage unit 14, an image processing unit 15, a transmission / reception unit 17, a display unit 19, and an input unit 21.

  The control unit 11 statically or dynamically controls the image processing apparatus 10 as a control center of the entire system.

  The main storage unit 13 stores image data (not restricted before and after reconstruction) collected by various modalities received by the transmission / reception unit 17 via the network. The main storage unit 13 stores a dedicated program for executing a curved slice image generation process described later.

  The external storage unit 14 is a recording medium such as a magnetic disk (floppy disk, hard disk, etc.), an optical disk (CD-ROM, DVD, etc.), and a semiconductor memory. The external storage unit 14 may store at least part of image data, programs, and the like stored in the main storage unit 13.

  The image processing unit 15 executes a curved slice image generation process. The configuration of the image processing unit 15 and the content of the curved slice image generation process will be described in detail later.

  The transmission / reception unit 17 transmits / receives various data including image data to / from various medical imaging apparatuses (for example, an X-ray computed tomography apparatus, an ultrasonic diagnostic apparatus, a magnetic resonance imaging apparatus, etc.) via a network.

  The display unit 19 is an output unit that displays the projection image received from the three-dimensional image projection unit 157 in a predetermined form.

  The input unit 21 has an input device (a mouse, a trackball, a mode switch, a keyboard, etc.) for capturing various instructions, commands, and information from an observer (operator).

(Function and configuration of image processing unit 15)
FIG. 2 is a block diagram illustrating a configuration of the image processing unit 15. As shown in the figure
The image processing unit 15 includes a three-dimensional image storage unit 151, a position data storage unit 152, a curved section data calculation unit 153, a curved section data storage unit 154, a line-of-sight data change unit 155, a line-of-sight data storage unit 156, and a three-dimensional image projection. Part 157.

  Note that the function and configuration of the image processing unit 15 is, for example, an auxiliary memory (not shown) that is installed by installing a dedicated program for executing the processing in the image processing apparatus 10 and reading out the program under the control of the control unit 11. It can be realized by developing on a section (memory). Of course, a program that can execute the functions of the image processing unit 15 is stored in a recording medium such as a magnetic disk (floppy disk, hard disk, etc.), an optical disk (CD-ROM, DVD, etc.), a semiconductor memory, or the like. It can also be distributed.

  However, the present embodiment is not intended to be limited to such a software configuration, and for example, at least a part of the configuration shown in FIG. 2 may be realized by a hardware configuration such as a graphic card.

  The 3D image storage unit 151 stores 3D image data read from the main storage unit 13.

  The position data storage unit 152 has predetermined position data (for example, a bend in a three-dimensional image, which will be described later) input via the input unit 21, another device via a network, a removable external storage device such as a CD. Blood vessel centerline data) that is an observation object.

  The curved section data calculation unit 153 inputs the blood vessel centerline data read from the position data storage unit 152 and the line-of-sight data read from the line-of-sight data storage unit 156, and generates curved section data by a predetermined calculation. . This calculation will be described later in detail.

  The curved section data storage unit 154 stores the curved section data generated by the curved section data calculation unit 153.

  The line-of-sight data changing unit 155 generates line-of-sight data in response to an operation from the input unit 31 for changing the line-of-sight direction. That is, the line-of-sight data changing unit 155 regards the direction and degree of movement of a mouse, a trackball, or the like as the amount of change in the viewpoint or the line-of-sight direction from the input data from the input unit 31, and creates line-of-sight data defining at least the line-of-sight direction. . The line-of-sight data may define the viewpoint in addition to the line-of-sight direction as necessary.

  The line-of-sight data storage unit 156 stores the line-of-sight data created by the line-of-sight data change unit 155.

  The three-dimensional image projection unit 157 is a projection method instructed by the control unit 11 based on the three-dimensional image read from the three-dimensional image storage unit 151 and the line-of-sight data read from the line-of-sight data storage unit 156. Is used to project a three-dimensional image to generate a projected image. The generated projection image is output to the image display unit 29 and displayed in a predetermined form.

  Further, based on the 3D image read from the 3D image storage unit 151, the line-of-sight data read from the line-of-sight data storage unit 156, and the curved section data stored in the curved section data storage unit 154. Then, a predetermined projection process is executed to generate a projection image. This projection processing will be described in detail later. The generated projection image is output to the image display unit 29 and displayed in a predetermined form.

(Curved section image generation processing)
FIG. 3 is a flowchart showing the procedure of the curved slice image generation process executed by the image processing apparatus 10. As shown in the figure, the curved cross-section image generation processing is mainly composed of the following three steps.

Step S1: Input a plurality of position data indicating the position of the observation object in the three-dimensional image.

Step S2: A curved section in the line-of-sight direction is obtained from the plurality of position data and the line-of-sight data for the three-dimensional image.

Step S3: Projecting a three-dimensional image on the curved section onto the projection plane based on the line-of-sight data.

  The processing of each step will be described in detail below.

[Step S1]
In this step, a plurality of position data indicating the position of the observation object in the three-dimensional image is input. If the input position data is n (n is a natural number greater than or equal to 2) and the entire position data is expressed as ^W K, the i-th position data ^w K _i is expressed by the following equation (1). is there.

Position data ^w K _i : ( ^w x _i , ^w y _i , ^w z _i ) i = 0, 1, 2,..., N-1 (1)
Here, ^w x _i , ^w y _i , and ^w z _i are the x coordinate, the y coordinate, and the z coordinate of the real space, respectively.

[Step S2]
In step S2, a curved section is calculated from the n pieces of position data input in step S1 and the line-of-sight data. The processing executed in this step is composed of the following three small steps as shown in steps S21 to S23 in FIG.

Step S2-1: The coordinates of the position data are converted from the real space coordinate system to the screen coordinate system.

Step S2-2: The coordinates in the depth direction of each point on the screen are obtained from the position data converted into the screen coordinate system.

Step S2-3: The coordinates of each point of the obtained screen coordinate system are converted into a real space coordinate system.

Hereinafter, processing in each small step will be described. In the following description, the transformation matrix from the real space coordinate system in which the volume data is arranged to the screen coordinate system is denoted as ^S T _W, and the inverse matrix is denoted as ^W T _S. ^W T _S is a transformation matrix from the screen coordinate system to the real space coordinate system. In this case, will be referred to as line-of-sight data are collectively ^S T _W and ^W T _S.

[Step S2-1]
In step S2-1, matrix calculation according to the following equation (2) is performed to obtain the coordinates of the position data ^s K _i in the screen coordinate system, that is, ( ^s x _i , ^s y _i , ^s z _i ).

^{_{t [S x i S y i}} S z i 1] = S T W t [W x i W y i W z i 1] (2)
Here, ^t [] means a transposed matrix. The element 1 in the transposed matrix exists because ^S T _W takes into account the shift amount (translation amount) between the two coordinate systems.

[Step S2-2]
In this step S2-2, the position data of the screen coordinate system obtained in step S2-2, obtains the data in the depth direction of the screen coordinate system of each point (pixel) ^S P on the screen. If the point of the coordinates ( ^S x, ^S y) on the screen is described as ^S P _{x, y} , the data in the depth direction (gaze direction) is the z coordinate value ^S z in the screen coordinate system. Information), and a set of ( ^S x, ^S y, ^S z) becomes data representing the desired curved section.

The real space position data ^w K _i converted to the screen coordinate system is named ^S K _i . ^Using a point ( ^S x _i , ^S y _i ) obtained by projecting ^S K _i on the screen, the distance D _i between ^S P _{x, y} and ( ^S x _i , ^S y _i ) is calculated by the following equation (3). (I = 0, 1, 2,..., N-1) is calculated.

D _i = (( ^S x _i - ^S x) ² + ( ^S y _i - ^S y) ² ) ^1/2 (3)
FIG. 4 is a conceptual diagram showing an example of the distance D _i between the point ^S P _{x, y} on the screen and ( ^S x _i , ^S y _i ).

Next, ^S z is obtained according to equations (4) and (5).

^S z = _Σ (δ _i ^S z _i ) / _Σ δ _i (i = 0,…, n-1) (4)
δ _i = 1 / D _i ^m (5)
Here, δ _i is a weight, and is considered so that the smaller the D _i is, that is, the larger the ^S K _i is closer to the point ( ^S x _i , ^S y _i ), the greater the weight.

When this calculation is executed for all points on the screen, data representing the desired curved section is obtained. m is a constant, and the larger the value, the smoother the curved cross section. When D _i is zero, that is, when ^S P _{x, y} is the same as the position data ^S K _i , the z coordinate ^S z _i of ^S K _i is used as data in the depth direction.

[Step S2-3]
In step S2-3, the coordinates ( ^S x, ^S y, ^S z) of the points on the curved section (intermediate curved section) obtained in step S2-2 are converted into real space coordinates by the following equation (6). Convert.

^{t [W x W y W z} 1] = W T S t [S x S y S z 1] (6)
Thus obtained ^{(W x, W y, W} z) is the set of a data in the real space of the curved cross-section.

[Step S3]
In step S3, a projection process for projecting a three-dimensional image using the curved cross-section data that can be placed in the real space in step S2 is executed. That is, in this step S3, for each point ( ^S x, ^S y) on the screen, the coordinates in the real space ( ^W x) corresponding to the coordinates ( ^S x, ^S y, ^S z) obtained in step S2-2. , ^W y, the pixel values of the three-dimensional image in ^W z) ^{(voxel) V (W x, W y} , to give a ^W z), it ^(S x, the projection processing of the pixel values in ^S y) Do.

FIGS. 5A and 5B are diagrams for explaining the results obtained by executing the curved cross-sectional image generation process on the three-dimensional CT image including the aorta. That is, FIG. 5 (a), shows the data ^S z of the resulting depth direction in step S2-2 as an image, black portions means that in front of the white portion. The line-of-sight direction is set to a direction in which the CT image is viewed from the front of the patient, and the value of m in step S2-2 is 8. Further, FIG. 5B shows the result of execution up to step S3. Since the cross-sectional shape of the entire aorta viewed from the line-of-sight direction is displayed in an easy-to-understand manner, and the direction of the line-of-sight is not different from the direction of viewing, the image is natural for the observer. For reference, a curve indicating the position of the blood vessel center line of the aorta is shown superimposed on the image.

  As the position data, data indicating the position of the blood vessel center line of the aorta is used. For example, “Ali Shahrokni et al,“ Fast skeltonization algorithm for 3-D elongated objects ”, Proceedings of SPIE Vol.4322, pp.323-330, 2001” “USP5,971,767”, “Onno Wink, Wiro J. Niessen,“ Fast Delineation and Visualization of Vessels in 3-D Angiographic Images ”, IEEE Trans. Med. Imag., Vol. 19, No. 4, 2000, etc. The disclosed technique can be used.

(Modification 1)
Next, a modification of this embodiment will be described. In this modification, in step S3, a projection method is employed in which the curved section obtained in step S2 is projected with a thickness.

  That is, a fixed thickness is given to the front and rear in the line-of-sight direction on the curved section obtained in step S2, and the projection area is set so that the thickness is equal to L voxels. The maximum voxel value among the voxels in the projection area that is on the line of sight perpendicular to each point on the screen and passes through the line of sight is projected as the pixel value of that point on the screen. This process is well known under the name of Maximum Intensity Projection.

  FIG. 5C shows an image obtained by setting L = 20 using the same three-dimensional CT image and blood vessel centerline data as in FIG. In the figure, not only the shape of the entire aorta as seen from the direction of the line of sight is well understood, but also blood vessels, organs, and bones around the aorta are depicted more easily.

  Further, the thickness may not be constant. For example, the entire region behind the curved cross section may be projected with respect to the line-of-sight direction. Further, the projection method may be a projection method other than the maximum value projection. For example, various projection methods can be applied depending on the interest, such as so-called volume rendering in which projection is performed using opacity and color.

(Modification 2)
Next, another modification of the present embodiment will be described. In this modification, the line-of-sight direction can be arbitrarily changed.

  That is, the line-of-sight data changing unit 155 calculates the amount of line-of-sight change based on a line-of-sight direction change instruction (for example, an instruction to move the pointer in a predetermined direction by a predetermined amount) by the input unit 21 such as a mouse or a trackball. Create new line-of-sight data.

  The curved section data calculation unit 17 calculates curved section data on screen coordinates based on the changed line-of-sight direction. Further, the three-dimensional image projection unit 157 generates a projection image obtained by projecting a curved section in the real space based on the changed line-of-sight direction. The obtained projected image is displayed on the image display unit 19 in a predetermined form.

  When the series of processes described above is repeated, every time the operator changes the line-of-sight direction, curved cross-sectional images are created and displayed one after another. Therefore, the operator can observe the cross section of the bent observation object from various directions only by operating the input unit for changing the line-of-sight direction. Needless to say, in step S3, when the same projection processing as that of the first modification is performed, a region having a thickness including a curved section is projected.

  According to the configuration described above, the following effects can be obtained.

  According to the present image processing apparatus, a curved section in real space is obtained from a curved section on a screen including a winding observation target, and data on the curved section in the real space or a region having a thickness including the curved section is obtained. Projecting. Therefore, it is possible to provide a projection image that allows the shape of the entire observation target to be easily grasped as compared with the conventional method of observing a cross section of an observation target that is winding as an image developed on a plane.

  In addition, according to the present image processing apparatus, a curved section image in a real space is calculated from the position data set for the bent observation target and the data in the line-of-sight direction, and is projected to generate a curved section image. To do. The curved section in the real space is obtained from the position data converted into the screen coordinate system using the coordinates in the depth direction of each point on the screen according to the line-of-sight direction. Therefore, a projection image is created using a curved section of real space viewed from the same direction as the direction in which the observer is viewing the 3D image, so that an image from a direction different from the direction in which the 3D image is viewed is displayed. Compared with the generated conventional technology, it is possible to provide a projection image that allows a natural observation of a winding object.

  Further, according to the present image processing device, when the line-of-sight direction is changed, a new curved section in real space viewed from the changed line-of-sight direction is created without inputting new cross-section position data. A projection image is generated using this. On the other hand, in the conventional method, even when the line-of-sight direction is changed, a new cross-sectional image cannot be generated unless new cross-section position data is input. Therefore, unlike the conventional case, it is possible to provide a projection image that can naturally observe a winding observation object regardless of how the line-of-sight direction is set.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. The image processing apparatus according to the present embodiment has a function of visualizing a blood vessel inner wall (a blood vessel inner wall visualization function) using the curved cross section obtained in the first embodiment. Hereinafter, the contents of the function and processing according to the function will be described according to the embodiment. For the sake of convenience, the curved cross section acquired in step S2 in FIG. 3 will be referred to as a “first type curved cross section”. In addition, a curved section generated by a process (vascular inner wall visualization process) according to the blood vessel inner wall visualization function using the first type curved section will be referred to as a “second type curved section”.

Example 1
The first embodiment generates a second type curved section by replacing a blood region existing on the first type curved section with a non-blood region that first appears from the blood region in the visual line depth direction. is there.

  FIG. 8 is a flowchart showing the flow of the blood vessel inner wall visualization process according to the present embodiment. First, as shown in the figure, a plurality of position data indicating the position of the observation object in the three-dimensional image is input (step S1), and from the input plurality of position data and the line-of-sight data for the three-dimensional image, A first type curved section in the viewing direction is calculated (step S2). These processes are the same as those in the first embodiment.

  Next, the curved surface data calculation unit 153 determines whether or not a voxel having a value within a predetermined range (value considered to be blood) exists on the first type curved surface (step S3a). As a result, when it is determined that the corresponding voxel does not exist on the first type curved section, the three-dimensional image projection unit 157 converts the three-dimensional data on the first type curved section based on the line-of-sight data. A display image is generated by projecting onto a two-dimensional plane (step S7a). This process is the same as the process in step S3 of FIG.

  On the other hand, when it is determined that a voxel having a value within a predetermined range exists on the first type curved section, the curved section data calculation unit 153 extracts the corresponding first voxel by extracting the corresponding voxel. A blood region existing on the cross section is specified (step S4a).

  Next, the curved cross-section data calculation unit 153 determines the voxel value along the line-of-sight depth direction from each position in the blood region, and specifies the first voxel having a value that does not correspond to blood, whereby the non-blood region ( That is, the blood vessel inner wall is specified (step S5 (a)). Further, the curved section data calculation unit 153 generates a second type curved section including the inner wall of the blood vessel by replacing the blood region on the first type curved section with the specified non-blood region (step S6a).

  Next, the three-dimensional image projection unit 157 generates a display image by projecting the generated three-dimensional data on the second type of curved section onto a two-dimensional plane based on the line-of-sight data (step S7a).

(Example 2)
In the second embodiment, 0 or (relative to the tissue) is applied to a voxel having a value within a predetermined range (value considered to be blood) together with a clipping process for removing data existing before the first type of curved section. By performing volume rendering processing with low transparency assigned, the inner wall of the blood vessel is actively imaged.

  FIG. 9 is a flowchart showing the flow of the blood vessel inner wall visualization process according to the present embodiment. First, as shown in the figure, a plurality of position data indicating the position of the observation object in the three-dimensional image is input (step S1), and from the input plurality of position data and the line-of-sight data for the three-dimensional image, A first type curved section in the viewing direction is calculated (step S2). These processes are the same as those in the first embodiment.

  Next, the 3D image projection unit 157 uses the first type of curved section as a clipping plane, and performs a clipping process to remove data in front of the clipping plane (step S3b). Further, the three-dimensional image projection unit 157 uses the clipped data to execute volume rendering processing in which low transparency (or transparency 0) is assigned to voxels having values corresponding to blood as shown in FIG. 10 ( Step S4b). Thereby, a volume rendering image in which the inner wall of the blood vessel is visualized can be generated. The opacity assigned to the voxel having a value corresponding to blood can be set to an arbitrary value.

(Example 3)
In Example 3, the blood vessel center line acquired in the first embodiment is used to identify the inner wall of the blood vessel, and this is replaced with the blood region on the first type curved surface, thereby generating the second type curved surface. To do.

  FIG. 11 is a flowchart showing the flow of the blood vessel inner wall visualization process according to the present embodiment. First, as shown in the figure, a plurality of position data indicating the position of the observation object in the three-dimensional image is input (step S1), and from the input plurality of position data and the line-of-sight data for the three-dimensional image, A first type curved section in the viewing direction is calculated (step S2). These processes are the same as those in the first embodiment.

  Next, the curved section data calculation unit 153 determines whether or not a voxel having a value corresponding to blood exists on the first type curved section (step S3c). As a result, when it is determined that the corresponding voxel does not exist on the first type curved section, the three-dimensional image projection unit 157 converts the three-dimensional data on the first type curved section based on the line-of-sight data. A display image is generated by projecting onto a two-dimensional plane (step S7c). This process is the same as the process in step S3 of FIG.

  On the other hand, when it is determined that a voxel having a value within a predetermined range exists on the first type curved section, the curved section data calculation unit 153 extracts the corresponding first voxel by extracting the corresponding voxel. A blood region existing on the cross section is specified (step S4c).

  Next, as shown in FIG. 12, the curved cross-section data calculation unit 153 determines voxel values for all angles along the radial direction from the blood vessel center line. For example, as shown in FIG. By specifying the first voxel changing as described above for each angle, the non-blood region (that is, the inner wall of the blood vessel) is specified (step S5 (c)). Furthermore, the curved cross-section data calculation unit 153 replaces the blood region on the first type curved cross-section with a non-blood region existing at a deeper position along the visual line depth direction from the blood region, thereby including a blood vessel inner wall. A two-kind cross section is generated (step S6c).

  Next, the three-dimensional image projection unit 157 generates a display image by projecting the generated three-dimensional data on the second type of curved section onto a two-dimensional plane based on the line-of-sight data (step S7c).

  In step S5 (c) of the present embodiment, the inner wall of the blood vessel may be specified based on the voxel value itself instead of the change rate of the voxel value. That is, the inner wall of the blood vessel can be specified by determining the voxel value along the entire radial direction from the blood vessel center line and specifying the first voxel having a value not corresponding to blood.

  The blood vessel inner wall visualized image generated by each method described above is displayed on the display unit 19 alone or together with the reference image, for example, in the form shown in FIG. Here, the reference image is obtained by visualizing the same object as the display image acquired by the method according to the first or second embodiment from the same line-of-sight direction. A typical example is a volume rendering image from the same line-of-sight direction regarding the same object. This reference image may be an image acquired by any modality. Further, when the image is displayed in the form as shown in FIG. 14, for example, when the line-of-sight direction and the enlargement ratio of the blood vessel inner wall visualized image are changed, the line-of-sight direction and the enlargement ratio of the reference image are also changed in synchronization therewith. It is preferable.

  Further, the display unit 19 may display the blood vessel inner wall visualized image together with the image visualized of blood as shown in FIGS. 5 (b) and 5 (c). Furthermore, the display unit 19 may synchronize and display the blood vessel inner wall visualized image, the blood visualized image, and the reference image as necessary.

  According to the configuration described above, the following effects can be obtained.

  According to this image processing apparatus, it is possible to generate and display a blood vessel inner wall visualized image in which blood is removed from the blood vessel images shown in FIGS. 5B and 5C and the blood vessel inner wall appears. Therefore, the inner wall of the blood vessel that could not be observed conventionally can be observed freely, which can contribute to the improvement of the quality of medical practice.

  Moreover, the blood vessel inner wall visualized image can be displayed in association with the reference image. Therefore, the observer can observe the entire diagnosis site by the reference image and the details by correlating the details by the visualized blood vessel inner wall image. Furthermore, by using together with the image acquired in the first embodiment, it is possible to freely observe the presence / absence of blood in the blood vessel according to the purpose. As a result, new diagnostic information can be provided and the degree of freedom in selecting diagnostic information can be expanded.

  Note that the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the components without departing from the scope of the invention in the implementation stage. Specific examples of modifications are as follows.

  In each of the above-described embodiments, for example, an image processing apparatus that executes a series of processes from setting of position data to a three-dimensional CT image to a projected image of a curved section has been described. On the other hand, for example, a configuration in which a projection image of a curved section is generated using at least one of position data, curved section data, line-of-sight data, etc. stored in advance in the main storage unit 13 or the like may be used. In such a case, since data stored in advance is used, an input operation by an observer can be omitted, and a predetermined data generation processing operation can be omitted.

  In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

  As described above, according to the present invention, it is possible to realize an image processing apparatus and an image processing method capable of generating a more useful cross-sectional image with a small work load when generating a cross-sectional image of a bent observation object.

FIG. 1 is a block diagram of an image processing apparatus 10 according to this embodiment. FIG. 2 is a block diagram illustrating a configuration of the image processing unit 15. FIG. 3 is a flowchart showing the procedure of the curved slice image generation process executed by the image processing apparatus 10. FIG. 4 is a conceptual diagram showing an example of the distance D _i between the point ^S P _{x, y} on the screen and ( ^S x _i , ^S y _i ). FIGS. 5A and 5B are diagrams for explaining the results obtained by executing the curved cross-sectional image generation process on the three-dimensional CT image including the aorta. FIG.5 (c) is a figure for demonstrating the modification 1 of this embodiment. FIG. 6 is a conceptual diagram for explaining C-MPR which is a method for displaying a cross section of an observation object. FIG. 7 is a conceptual diagram for explaining C-PC, which is a method for displaying a cross section of an observation object. FIG. 8 is a flowchart illustrating the flow of the blood vessel inner wall visualization process according to the first embodiment. FIG. 9 is a flowchart illustrating the flow of the blood vessel inner wall visualization process according to the second embodiment. FIG. 10 is a diagram for explaining opacity assignment in volume rendering. FIG. 11 is a flowchart illustrating the flow of the blood vessel inner wall visualization process according to the third embodiment. FIG. 12 is a diagram for explaining a method for specifying a non-blood region using a blood vessel center line. FIG. 13 is a diagram showing a change in the voxel value along the radial direction. FIG. 14 is a diagram illustrating an example of the display form of the reference image.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Image processing apparatus, 11 ... Control part, 13 ... Main memory part, 14 ... External storage part, 15 ... Image processing part, 17 ... Transmission / reception part, 19 ... Display part, 21 ... Input part, 15 ... Image processing part, DESCRIPTION OF SYMBOLS 31 ... Input part, 151 ... Three-dimensional image storage part, 152 ... Position data storage part, 153 ... Curve cross section data calculating part, 154 ... Curve cross section data storage part, 155 ... Gaze data change part, 156 ... Gaze data storage part, 157 ... 3D image projection unit

Claims (27)

On the input three-dimensional image data of the observation object, a position data specifying unit for specifying a plurality of position data indicating the position of the observation object;
A curved section calculation unit for calculating a first curved section in the line-of-sight direction from the plurality of position data and line-of-sight data including a desired line-of-sight direction;
A projection image is generated by projecting the three-dimensional image data on the first curved section or the three-dimensional image data relating to the region based on the first curved section onto the projection plane along the line-of-sight direction. A projection image generation unit;
A display unit for displaying the projected image;
An image processing apparatus comprising:   The image processing apparatus according to claim 1, wherein the curved section calculation unit calculates the first curved section using depth information regarding the line-of-sight direction of each position data.   3. The image processing apparatus according to claim 1, wherein the curved section calculation unit calculates the first curved section using a weight whose coefficient changes according to a distance from the plurality of position data. . The curved section calculation unit is
The plurality of position data set on the three-dimensional image data is converted into a screen coordinate system, and information on the depth of each position data in the screen coordinate system is used to obtain an intermediate curved section in the screen coordinate system. To calculate
Calculating the first curved section in the line-of-sight direction by inversely transforming the intermediate curved section into a three-dimensional space;
The image processing apparatus according to claim 1, wherein the image processing apparatus is an image processing apparatus. Further comprising a line-of-sight changing unit for changing the line-of-sight data;
The curved section calculation unit calculates the first curved section using the line-of-sight data after the change when the line-of-sight data is changed by the line-of-sight change unit;
The image processing apparatus according to claim 1, wherein the image processing apparatus is an image processing apparatus. The curved section calculation unit is
Based on the value of each voxel constituting the three-dimensional image data, the blood region existing on the first curved section and the first non-blood region appearing along the line-of-sight direction from the blood region are identified. And
By replacing the blood region and the non-blood region present on the first curved cross section, a second curved cross section is generated,
The projection image generation unit projects the three-dimensional image data on the second curved section or the three-dimensional image data related to the region based on the second curved section onto the projection plane along the line-of-sight direction. Generating the projection image by
The image processing apparatus according to claim 1, wherein the image processing apparatus is an image processing apparatus. The projection image generation unit includes:
Generate clipping data by executing a clipping process that removes data existing before the first curved section from the three-dimensional image data of the observation object,
Generating the projected image by performing volume rendering with a relatively low opacity assigned to the tissue for voxels having a value corresponding to blood using the clipping data;
The image processing apparatus according to claim 1, wherein the image processing apparatus is an image processing apparatus. The curved section calculation unit is
Based on the plurality of position data and the rate of change of the value of each voxel constituting the three-dimensional image data, a blood region existing on the first curved section, and the blood region along the line-of-sight direction Identify the first non-blood region that appears,
By replacing the blood region and the non-blood region present on the first curved cross section, a second curved cross section is generated,
The projection image generation unit projects the three-dimensional image on the second curved section or the three-dimensional image related to the region based on the second curved section onto the projection plane along the line-of-sight direction. Generating the projected image;
The image processing apparatus according to claim 1, wherein the image processing apparatus is an image processing apparatus.   The image according to any one of claims 1 to 8, wherein the display unit simultaneously displays the projection image in association with a reference image obtained by visualizing the observation object from the line-of-sight direction. Processing equipment.   The image processing apparatus according to claim 1, wherein the position data is data related to a blood vessel center line. An acquisition unit for acquiring three-dimensional image data to be observed;
On the three-dimensional image data, a position data specifying unit for specifying a plurality of position data indicating the position of the observation object;
A curved section calculation unit for calculating a first curved section in the line-of-sight direction from the plurality of position data and line-of-sight data including a desired line-of-sight direction;
A projection image is generated by projecting the three-dimensional image data on the first curved section or the three-dimensional image data relating to the region based on the first curved section onto the projection plane along the line-of-sight direction. A projection image generation unit;
A display unit for displaying the projected image;
A medical image diagnostic apparatus comprising:   The medical image diagnostic apparatus according to claim 11, wherein the curved section calculation unit calculates the first curved section using depth information regarding the line-of-sight direction of each position data.   The medical image diagnosis according to claim 11 or 12, wherein the curved section calculation unit calculates the first curved section using a weight whose coefficient changes in accordance with a distance from the plurality of position data. apparatus. The curved section calculation unit is
The plurality of position data set on the three-dimensional image data is converted into a screen coordinate system, and information on the depth of each position data in the screen coordinate system is used to obtain an intermediate curved section in the screen coordinate system. To calculate
Calculating the first curved section in the line-of-sight direction by inversely transforming the intermediate curved section into a three-dimensional space;
The medical image diagnostic apparatus according to claim 11, wherein the medical image diagnostic apparatus is a medical image diagnostic apparatus. Further comprising a line-of-sight changing unit for changing the line-of-sight data;
The curved section calculation unit calculates the first curved section using the line-of-sight data after the change when the line-of-sight data is changed by the line-of-sight change unit;
The medical image diagnostic apparatus according to claim 11, wherein the medical image diagnostic apparatus is any one of claims 11 to 14. The curved section calculation unit is
Based on the value of each voxel constituting the three-dimensional image data, the blood region existing on the first curved section and the first non-blood region appearing along the line-of-sight direction from the blood region are identified. And
By replacing the blood region and the non-blood region present on the first curved cross section, a second curved cross section is generated,
The projection image generation unit projects the three-dimensional image data on the second curved section or the three-dimensional image data related to the region based on the second curved section onto the projection plane along the line-of-sight direction. Generating the projection image by
The medical image diagnostic apparatus according to claim 11, wherein the medical image diagnostic apparatus is any one of claims 11 to 14. The projection image generation unit includes:
Generate clipping data by executing a clipping process that removes data existing before the first curved section from the three-dimensional image data of the observation object,
Generating the projected image by performing volume rendering with a relatively low opacity assigned to the tissue for voxels having a value corresponding to blood using the clipping data;
The medical image diagnostic apparatus according to claim 11, wherein the medical image diagnostic apparatus is any one of claims 11 to 14. The curved section calculation unit is
Based on the plurality of position data and the rate of change of the value of each voxel constituting the three-dimensional image data, a blood region existing on the first curved section, and the blood region along the line-of-sight direction Identify the first non-blood region that appears,
By replacing the blood region and the non-blood region present on the first curved cross section, a second curved cross section is generated,
The projection image generation unit projects the three-dimensional image on the second curved section or the three-dimensional image related to the region based on the second curved section onto the projection plane along the line-of-sight direction. Generating the projected image;
The medical image diagnostic apparatus according to claim 11, wherein the medical image diagnostic apparatus is any one of claims 11 to 14.   19. The medical device according to claim 11, wherein the display unit simultaneously displays the projection image in association with a reference image obtained by visualizing the observation object from the line-of-sight direction. Diagnostic imaging device.   The medical image diagnostic apparatus according to claim 11, wherein the position data is data related to a blood vessel center line. On the input three-dimensional image data of the observation object, specify a plurality of position data indicating the position of the observation object,
From the plurality of position data and gaze data including a desired gaze direction, a first curved section in the gaze direction is calculated,
A projection image is generated by projecting the three-dimensional image data on the first curved section or the three-dimensional image data related to the region based on the first curved section onto the projection plane along the line-of-sight direction. ,
Displaying the projected image;
An image processing method comprising:   The image processing method according to claim 21, wherein, in the first curved section calculation, the first curved section is calculated using depth information regarding the line-of-sight direction of each position data.   23. The first curved cross section according to claim 21 or 22, wherein, in the first curved cross section calculation, the first curved cross section is calculated using a weight that changes a coefficient according to a distance from the plurality of position data. Image processing method. Based on the value of each voxel constituting the three-dimensional image data, the blood region existing on the first curved section and the first non-blood region appearing along the line-of-sight direction from the blood region are identified. And
By replacing the blood region and the non-blood region present on the first curved cross section, a second curved cross section is generated,
A projection image is generated by projecting the three-dimensional image data on the second curved section or the three-dimensional image data relating to the region based on the second curved section onto the projection plane along the line-of-sight direction. thing,
The image processing method according to claim 21, further comprising: Generate clipping data by executing a clipping process that removes data existing before the first curved section from the three-dimensional image data of the observation object,
Using the clipping data to generate a projected image by performing volume rendering with a relatively low opacity assigned to tissue for voxels having a value corresponding to blood;
The image processing method according to claim 21, further comprising: Based on the plurality of position data and the rate of change of the value of each voxel constituting the three-dimensional image data, a blood region existing on the first curved section, and the blood region along the line-of-sight direction Identify the first non-blood region that appears,
By replacing the blood region and the non-blood region present on the first curved cross section, a second curved cross section is generated,
Generating a projection image by projecting the three-dimensional image on the second curved section or a three-dimensional image related to the region based on the second curved section onto the projection plane along the line-of-sight direction;
The image processing method according to claim 21, further comprising:   27. The image processing method according to claim 21, wherein, in displaying the projection image, the observation object is simultaneously displayed in association with a reference image visualized from the line-of-sight direction. .

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