JP2010088803A - 3d image processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily obtain the shape of a medical instrument, etc., indwelled in a subject. <P>SOLUTION: An image data storage part 11 stores data of a plurality of slice images concerning the medical instrument indwelled in the subject. An image generating part 13 generates data of a plurality of projection images with different projection ranges, based on the plurality of slice images stored in the image data storage part 11. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a three-dimensional image processing apparatus that processes data of a three-dimensional image related to a medical instrument.

  The technique of intravascular intervention is becoming popular. This procedure involves making a small hole in the thigh and hand of the foot, inserting a device such as a guide wire or catheter into the blood vessel (arteries or veins) from here, carrying the device to the lesion in the heart, brain or lower limbs, This is a surgical method to treat the lesion. Compared to conventional laparotomy, it is a treatment method that has been growing in recent years because the pain given to patients is extremely small.

  For example, suppose that a lesion to be treated is narrowed. In the stenosis, the flow of blood flow is hindered, and an intravascular device called a stent is placed for the purpose of expanding the stenosis and further preventing restenosis in order to secure sufficient blood flow downstream. This stent has a cylindrical mesh.

  In a general clinical workflow, a doctor places a stent on a target site, expands it, generates a three-dimensional image by rotational imaging, and visually observes the three-dimensional image. Usually, it was visually confirmed whether or not the stent was sufficiently expanded in a columnar shape, and the diameter and length after the stent expansion were measured.

In addition, as a well-known document relevant to this application, there exist the following, for example.
JP 2005-288164 A

  As described above, a doctor observes a portion of a stent that has been placed in an inadequate portion of an unexpanded portion with the above three-dimensional image. However, it is difficult to determine whether or not the expansion is poor only by displaying a slice image. is there.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a three-dimensional image processing apparatus capable of easily grasping the shape and the like of a medical instrument placed on a subject.

  In order to achieve the above object, according to one aspect of the present invention, a storage unit that stores data of a plurality of slice images related to a medical device placed in a subject, and a plurality of projection ranges different from the stored slice images And an image generation unit that generates projection image data.

  As described above, according to the present invention, it is possible to provide a three-dimensional image processing apparatus capable of easily grasping the shape and the like of a medical instrument placed on a subject.

  Hereinafter, a three-dimensional image processing apparatus according to the present invention will be described with reference to the drawings. In the following embodiments, the three-dimensional image processing apparatus will be described as being incorporated in an X-ray imaging apparatus.

  FIG. 1 is a configuration diagram of an X-ray imaging apparatus equipped with a three-dimensional image processing apparatus according to an embodiment of the present invention. The X-ray imaging apparatus has a C arm 5. The C-arm 5 is supported so as to be rotatable about three orthogonal axes by a floor-mounted or ceiling-supporting mechanism (not shown). An X-ray tube 1 is attached to one end of the C arm 5. The X-ray control unit 4 applies a tube voltage between the electrodes of the X-ray tube 1 to generate X-rays from the X-ray tube 1 in accordance with the control of the system control unit 9, and the cathode filament of the X-ray tube 1 To supply a heating current. An X-ray detector 2 is attached to the other end of the C arm 5. The X-ray tube 1 and the X-ray detector 2 face each other with the subject P on the top 3 interposed therebetween. The X-ray detector 2 is composed of, for example, a combination of an image intensifier and a TV camera. Alternatively, the X-ray detector 2 includes a flat panel detector (FPD: planar X-ray detector) having semiconductor detection elements arranged in a matrix. The C-arm rotation mechanism 6 supplies electric power to the drive source for rotating the C-arm 5 according to the control of the system control unit 9. By repeating imaging while the C-arm 5 rotates, a multi-directional X-ray image (projection image) necessary for three-dimensional image reconstruction can be acquired.

  The rotation of the C-arm 5, the application of a high voltage to the X-ray tube 21, and the signal reading of the X-ray detector 2 are controlled by the system control unit 9, and the data of a plurality of projection images having different imaging directions are controlled by the image acquisition circuit 10. Are collected. Further, in the present X-ray imaging apparatus, an electrocardiograph 10 is equipped to measure the subject P and generate an electrocardiogram. The image data storage unit 11 stores data of a plurality of projection images collected by the image collection circuit 10 in association with the shooting direction data.

  The reconstruction processing unit 12 reconstructs volume data based on a plurality of projection images having different shooting directions stored in the image data storage unit 11. In the present embodiment, data of a plurality of slice images related to a stent placed in a target site in intravascular intervention is stored in the image data storage unit 11.

  The operation unit 8 is provided to transmit various commands from the user to the system control unit 9, and includes various input devices such as a keyboard and a mouse. The monitor 7 includes a CRT (cathode-ray tube), a liquid crystal display (LCD), or the like.

  Furthermore, in the present embodiment, an image generation unit 13, a display processing unit 14, and an index measurement unit 15 are provided in order to make it easier to grasp a portion of the stent that has been placed on the subject that is not sufficiently expanded. FIG. 2 shows an example of the shape of the stent. As shown in FIG. 2, a stent generally has a mesh structure. For this reason, there is a problem that a complicated calculation is required to measure the diameter of the stent, and that it is difficult to understand by a simple display method to indicate that the diameter is smaller than the standard value. For example, the right side of FIG. 2 is a stent slice image (cross-sectional image). In order to measure the diameter of a stent from this slice image, complicated processing such as imagining a line connecting points is required.

  Therefore, the image generation unit 13 generates data of a plurality of projection images having different projection ranges from the plurality of slice images stored in the image data storage unit 11. The display processing unit 14 displays the generated projection image on the monitor 7. The index measuring unit 15 measures an index related to the shape of the stent (for example, the diameter or eccentricity of the cross section of the stent) from the stent image on the projection image generated by the image generating unit 13.

  Hereinafter, specific processing contents of the image generation unit 13, the index measurement unit 15, and the display processing unit 14 will be described according to each embodiment.

Example 1
In the first embodiment, an image suitable for measuring a diameter or the like is generated from a plurality of slice images related to a stent imaged by an X-ray imaging system.

  As shown in FIG. 2 above, in the three-dimensional image of the reconstructed stent, white dots indicate stent nets (stent struts). Since the stent is a mesh-like cylinder, dotted lines appear in a slice image as a circle. When the diameter of a stent is automatically measured by a computer, in the conventional method, for example, a line connecting a white point and a white point is assumed to be a circle and the diameter of the circle is measured. For this reason, the measurement result may not be obtained correctly if a line connecting the white point and the white point cannot be obtained successfully due to noise or other factors.

  Thus, in the first embodiment, an image processing method for generating an image suitable for measuring a diameter or the like from a plurality of slice images of a stent will be described. FIG. 3 is a diagram for explaining the operation of the first embodiment. FIG. 4 is a flowchart illustrating an image processing procedure according to the first embodiment.

  In FIG. 4, the image generation unit 13 divides the data of the plurality of slice images stored in the image data storage unit 11 into sections of different projection ranges in the axial direction of the stent (step S1a). For example, the section length may be preset to about 0.5 to 20 mm, or may be provided with a GUI (Graphical User Interface) that can be adjusted by the operator. Further, the section may be divided not only as shown in FIG. 3 but also as shown in FIG.

  The image generation unit 13 generates a maximum value projection (MIP) image from the slice image in the section (step S2a). By performing the process of step S2a on each section, a MIP image for each section is generated and displayed on the screen of the monitor 7 by the display processing unit 14. Since the stent has a cylindrical mesh shape, when an MIP image is generated from a plurality of slice images, dots are connected to form a circle as shown on the right in FIG. The index measuring unit 15 measures an index (center, diameter, eccentricity, etc.) regarding the shape of the stent from the generated MIP image (step S3a).

  According to the first embodiment, a complicated process of virtualizing a line connecting points is unnecessary, and the diameter of a circle is accurately measured. You will be able to grasp.

  In the first embodiment, the MIP process is performed for each section. Alternatively, an average value process or a minimum value process may be performed. If the section length is all sections (from the end of the stent to the end), the average diameter of the stent can be measured.

(Example 2)
In the second embodiment, the technique shown in the first embodiment can be applied to a bent blood vessel.

  As shown in FIG. 6, even if an actual human blood vessel is localized, it is often bent. When a MIP image for each section is generated as in the first embodiment in a state where the blood vessel is bent, the stent image is displaced on the generated MIP image.

  Therefore, in the second embodiment, an image processing method that can cope with such a case where the blood vessel is bent is proposed. FIG. 7 is a diagram for explaining the operation of the second embodiment. FIG. 8 is a flowchart illustrating an image processing procedure according to the second embodiment.

  First, as in the first embodiment, the image generation unit 13 divides the data of the plurality of slice images stored in the image data storage unit 11 into sections of different projection ranges in the axial direction of the stent (step S1b), A MIP image is generated from the slice image (step S2b). Thereby, a plurality of MIP images are created.

  Next, the image generation unit 13 corrects the displacement of the stent image between the MIP images (step S3b). Since the stent image is depicted as a circle on each MIP image, alignment processing is performed so as to maximize the cross-correlation between the MIP images in the preceding and following sections. Then, based on the obtained positional deviation amount, a process of translating the position of the stent image on each MIP image is performed. As a result, in all the MIP images, MIP images corrected so that the centers of the stents are aligned are obtained. Further, by generating MIP images for all sections based on the corrected MIP image (step S4b), a circle in which the centers of the stent images are aligned is drawn. The index measurement unit 15 measures the average diameter of the stent using the generated MIP images of all sections (step S5b).

  As described above, in the second embodiment, even when the blood vessel is bent by correcting the positional deviation of the slice image on the MIP image with respect to the plurality of MIP images generated as in the first embodiment, The average diameter of the stent can be accurately measured. In addition to the cross-correlation method, other algorithms can be used as a method for correcting misalignment.

(Example 3)
Example 3 provides a new index in measuring the shape of a stent.

  As a measurement result of a stent, one that outputs a diameter and a length is conventionally known. It can also be easily analogized to measure the eccentricity. In addition to these, the third embodiment proposes to measure a new index called “curvature”. FIG. 9 is a diagram for explaining the operation of the third embodiment. FIG. 10 is a flowchart illustrating an image processing procedure according to the third embodiment.

  First, similarly to the first embodiment, the image generation unit 13 divides the data of the plurality of slice images stored in the image data storage unit 11 into sections of different projection ranges in the axial direction of the stent (step S1c), A MIP image is generated from the slice image (step S2c). Thereby, a plurality of MIP images are created.

  The index measurement unit 15 obtains the center coordinates (ui, vi) of the stent image on each MIP image in the process of measuring the diameter of the stent from each MIP image as in the first embodiment (step S3c). . Since each slice image is an element in the three-dimensional image, the coordinates (ui, vi) can be converted into three-dimensional coordinates (xi, yi, zi) (step S4c). The index measuring unit 15 calculates a three-dimensional curved approximate curve L connecting the converted three-dimensional coordinates (xi, yi, zi), and calculates a curvature R of the curved line L (step S5c).

  There are various types of stents, each having a different “hardness”. The stent is easily bent or difficult to bend due to this hardness. The doctor knows this "hardness" from the data sheet and experience. Therefore, the index measurement unit 15 compares the calculated “curvature” with the “hardness” of each stent, and issues a “warning” when the bending exceeds the standard hardness. . Bending beyond the standard means that the stent has been subjected to a force that exceeds its proof strength, and the stent may be subject to fatigue fracture in the future, or extra force may be applied to the surrounding blood vessels. Because it is expensive, warnings can help prevent future accidents.

Example 4
Example 4 is a method of displaying an abnormally expanded portion of a stent in an easy-to-understand manner.
After the doctor expands the stent, he wants to know if the stent is spreading properly. For example, if a portion of a blood vessel is calcified and hard, the stent may be underexpanded only in that area. In order to capture such a phenomenon, the current two-dimensional image cannot be captured depending on the projection direction, which is a problem. Even a three-dimensional stent image remains difficult to capture depending on the display method. For example, it is difficult to determine whether or not the stent is properly spread even in a cross-sectional image as shown in the right of FIG.

  Therefore, in the fourth embodiment, the slice image is displayed so as to overlap the MIP image generated in the first embodiment. FIG. 11 is a diagram for explaining the operation of the fourth embodiment. FIG. 12 is a flowchart illustrating an image processing procedure according to the fourth embodiment.

  First, as in the first embodiment, the image generation unit 13 divides the data of the plurality of slice images stored in the image data storage unit 11 into sections of different projection ranges in the axial direction of the stent (step S1d), An MIP image is generated from the slice image (step S2d). Thereby, a plurality of MIP images are created.

  Next, the display processing unit 14 superimposes the slice image in the section on the generated MIP image and displays it on the monitor 7 (step S3d). At this time, the MIP image to be displayed may be an MIP image of a partial section or an MIP image of the entire section, but a longer section is preferable. As a result, the spread of the slice relative to the average spread of the stent can be recognized at a glance, and the abnormally expanded portion of the stent can be easily understood.

(Example 5)
In Example 5, the abnormal part of the stent is made easier to understand in Example 4.
FIG. 13 is a diagram for explaining the operation of the fifth embodiment. FIG. 14 is a flowchart illustrating an image processing procedure according to the fifth embodiment.

  First, as in the first embodiment, the image generation unit 13 divides the data of the plurality of slice images stored in the image data storage unit 11 into sections of different projection ranges in the axial direction of the stent (step S1e), An MIP image is generated from the slice image (step S2e). Thereby, a plurality of MIP images are created.

  Next, the image generation unit 13 generates MIP images for all sections based on the generated MIP images for each section (step S3e). The display processing unit 14 displays the MIP image for each section on the MIP image for all sections on the monitor 7 (step S4e). Further, the display processing unit 14 displays a difference portion between the displayed MIP image of all the sections and the MIP image of each section in a color or the like (step S4e).

  As described above, according to the fifth embodiment, the doctor can more accurately grasp the abnormal expansion portion of the stent. In step S4e, as shown in FIG. 13, the difference portion can be displayed as a projection image, the area of the difference portion can be measured and displayed, or the area can be displayed as a graph. Further, the projection direction in which the difference portion can be seen well is calculated so that the doctor can easily recognize how much the expansion is insufficient compared with the good expansion portion, and the C-arm rotation mechanism 6 is driven in that direction. You may do it.

  In addition, this invention is not limited to the said embodiment as it is. For example, the above embodiment can be used for a case where two stents are arranged in series in addition to a single stent, or when a stent is arranged at a branching portion. Moreover, although the said embodiment is useful especially in a stent, of course, it is applicable also to other medical devices, such as a balloon.

  In the above-described embodiment, the above-described embodiment uses the cardiovascular X-ray image for the description. However, the present invention is not limited to the X-ray image, and medical images collected by other systems such as a CT image, an MRI image, and an ultrasound image are used. Extension to images is also possible.

  In the above embodiment, the three-dimensional image processing apparatus according to the present invention has been described as a configuration integrated with the X-ray imaging apparatus, but includes an image data storage unit, an image generation unit, a display processing unit, an index measurement unit, and a monitor. In addition, the three-dimensional image processing apparatus can be configured separately and independently.

  Each function according to the present embodiment can also be realized by installing a program for executing the processing in a computer such as a workstation and developing the program on a memory. At this time, a program capable of causing the computer to execute the technique is stored in a recording medium such as a magnetic disk (floppy (registered trademark) disk, hard disk, etc.), an optical disk (CD-ROM, DVD, etc.), or a semiconductor memory. It can also be distributed.

  In short, 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. For example, various inventions can be formed by appropriately combining a plurality of constituent elements 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.

The figure which shows one Embodiment of the X-ray imaging apparatus provided with the three-dimensional image processing apparatus which concerns on this invention. The figure which shows an example of the shape of a stent. FIG. 3 is a diagram illustrating an operation of the first embodiment. 3 is a flowchart illustrating an image processing procedure according to the first exemplary embodiment. FIG. 6 is a diagram illustrating another example of a section in the first embodiment. The figure which shows the stent indwelled in the blood vessel of the bent state. FIG. 6 is a diagram illustrating an operation of the second embodiment. 9 is a flowchart illustrating an image processing procedure according to the second embodiment. FIG. 10 is a diagram illustrating the operation of the third embodiment. 10 is a flowchart illustrating an image processing procedure according to the third embodiment. FIG. 10 is a diagram illustrating the operation of the fourth embodiment. 10 is a flowchart illustrating an image processing procedure according to the fourth embodiment. FIG. 10 is a diagram illustrating the operation of the fifth embodiment. 10 is a flowchart illustrating an image processing procedure according to the fifth embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... X-ray tube, 2 ... X-ray detector, 3 ... Top plate, 4 ... X-ray control part, 5 ... C arm, 6 ... C arm rotation mechanism, 7 ... Monitor, 8 ... Operation part, 9 ... System control , 10 ... an image collection circuit, 11 ... an image data storage unit, 12 ... a reconstruction processing unit, 13 ... an image generation unit, 14 ... a display processing unit, 15 ... an index measurement unit.

Claims (5)

A storage unit for storing data of a plurality of slice images related to a medical instrument placed in the subject;
A three-dimensional image processing apparatus comprising: an image generation unit that generates data of a plurality of projection images having different projection ranges from the plurality of stored slice images.   The said image generation part further correct | amends the position shift of the image of the said medical device on the produced | generated several projection image based on the correlation of the produced | generated several projection image. 3D image processing apparatus.   2. The three-dimensional image according to claim 1, further comprising an index measurement unit that measures an index related to a shape of the medical device based on a position of an image related to the medical device on the plurality of generated projection images. Image processing device.   The three-dimensional image processing apparatus according to claim 1, further comprising a display processing unit that displays the plurality of slice images on the generated projection image.   The three-dimensional image processing apparatus according to claim 4, wherein the display processing unit further displays a difference between the displayed projection image and a slice image.

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