Computer simulator for treatment planning of cerebral aneurysms

Abstract

A computer simulator for use in selecting a device 14 and planning a treatment for a brain aneurysm 12.SOLUTION: With device 14 inserted in cerebral aneurysm 12, the three dimensional image is equally divided by a cutting plane 18 perpendicular to a centerline 16 of cerebral aneurysm 12 or device 14. The positional relation between the outer peripheral surface of the device 14 and the inner wall of the cerebral aneurysm 12 or the degree of a gap generated between them is obtained for each divided part. The result is colored and displayed on the three dimensional image of the cerebral aneurysm 12. The length in the direction along the center line of the device in the cerebral aneurysm is calculated, and an image of the device actually inserted into the cerebral aneurysm is drawn.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a computer simulator used for selecting a device and planning treatment for cerebral aneurysms. [Background technology]

[0002] A method using a pouch-like device made of woven braided mesh has been developed as a treatment for intracranial cerebral aneurysms (Patent Document 1) (Patent Document 2). This pouch-like device creates a wall inside the cerebral aneurysm or blocks the neck of the cerebral aneurysm, promoting the formation of a blood clot within the aneurysm and preventing the aneurysm from rupturing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-163180 [Patent Document 2] Japanese Patent Publication No. 2022-168039 Summary of the Invention [Problem to be solved by the invention]

[0004] The surgical insertion of this device requires the selection of an appropriate device according to the shape of the cerebral aneurysm and the consideration of the optimal treatment method. The present invention provides a computer simulator for planning treatment of cerebral aneurysms. [Means for solving the problem]

[0005] The following configurations are means for solving the above problems.

[0006] <Configuration 1> A computer simulator for planning treatment of cerebral aneurysms displays a three-dimensional image of a device inserted into a cerebral aneurysm, the device being made of a self-expanding elastic braid that expands without the application of external force, divides the three-dimensional image of the device and cerebral aneurysm into multiple annular sections along a cross section that passes through the vertices of the diamond-shaped braid that makes up the device's braid and is perpendicular to the center line of the device, determines the relationship between the envelope of the divided device and the inner wall of the cerebral aneurysm, and displays the results in a colored three-dimensional image of the cerebral aneurysm.

[0007] <Configuration 2> A computer simulator for treatment planning for cerebral aneurysms according to configuration 1, characterized in that the divided annulus of the cerebral aneurysm is divided into a plurality of segments, and for each segment, the segment is displayed in a first color when the envelope of the device is positioned so that it sinks into the inner wall of the cerebral aneurysm by a certain amount or more, the segment is displayed in a second color when the envelope of the device is positioned so that it just contacts the inner wall of the cerebral aneurysm, and the segment is displayed in a third color when the envelope of the device is positioned so that a gap of a certain amount or more occurs between the envelope of the device and the inner wall of the cerebral aneurysm 12.

[0008] <Configuration 3> A computer simulator for treatment planning for cerebral aneurysms according to configuration 1, characterized in that when the envelope surface of the device is positioned so as to sink into the inner wall of the cerebral aneurysm to a certain extent or more, the radial expansion of the envelope surface of the device is considered to be prevented by the inner wall of the cerebral aneurysm, and the length of the center line is calculated from the above-mentioned diamond shape of that part, and when the calculated length of the center line exceeds the length of the center line when the device is expanded without the application of external force and exceeds the neck plane of the cerebral aneurysm, the exceeding part is displayed in a fourth color.

[0009] <Configuration 4> A device in an expanded state without external force is divided into n pieces in a cross section perpendicular to its center line, and the perimeter of each of the obtained rings is defined as Lm (m = 1 to n), and the width of each ring as viewed in the direction of the center line of the device is defined as wm (m = 1 to n). The relation between the perimeter Lm of the ring and its width wm is determined as wm = f(Lm), When a device is inserted into a cerebral aneurysm, if there are areas of the inner wall of the cerebral aneurysm that are prevented from expanding, The amount by which the circumference of each of the n annulus of the device in the cerebral aneurysm has decreased from the original circumference Lm is measured from the image data, and the new width of each annulus is calculated using the above formula and added together. A method for calculating the length along the centerline of a device within a cerebral aneurysm.

[0010] <Configuration 5> A computer simulator for treatment planning for cerebral aneurysms, characterized in that it uses position data of all annuli obtained by the method described in configuration 4 to draw an image of a device actually inserted inside the cerebral aneurysm. <Configuration 6> A computer simulator for treatment planning of cerebral aneurysms, characterized in that the positional relationship between all annulus of the device obtained by the method described in configuration 4 and the annulus of the cerebral aneurysm around it is displayed in color on a three-dimensional image of the cerebral aneurysm so that it is possible to distinguish between appropriate and inappropriate cases. <Configuration 7> A computer simulator for treatment planning of cerebral aneurysms, characterized in that it displays a colored three-dimensional image of the cerebral aneurysm obtained by the method described in Configuration 4, so that it is possible to distinguish between appropriate and inappropriate positional relationships between a device inserted inside the cerebral aneurysm and nearby blood vessels. <Configuration 8> 8. A computer simulator for treatment planning of cerebral aneurysms in configuration 6 or 7, characterized in that it colors a three-dimensional image of the cerebral aneurysm and displays a numerical index, a volume filling rate, or a surface contact rate. [Effects of the Invention]

[0011] <Effects of Configuration 1> Three-dimensional images of an expanded device inserted into a cerebral aneurysm without external force can be used to simulate the device and help select the optimal shape. Three-dimensional images of the device and cerebral aneurysm are divided into sections perpendicular to the center line of the device, passing through the vertices of the diamonds that make up the braided body of the device, and each annular section is compared, allowing the coordinate data used when the device was designed to be used. <Effects of Configuration 2> Images of the cerebral aneurysm and the device are superimposed to allow the optimal device shape to be selected. The size of the device may be too large, just right, or too small compared to the cerebral aneurysm. The entire cerebral aneurysm is divided into multiple segments and displayed in different colors, allowing the condition of each part of the cerebral aneurysm to be confirmed in detail when the device is inserted. <Effects of Configuration 3> When the device is actually inserted into a cerebral aneurysm, no part of the device will extend beyond the inner wall of the aneurysm, thereby preventing the device from expanding radially. When this occurs in any part of the device, the size of the device will increase along the centerline. At this time, no part of the device should extend beyond the neck plane of the cerebral aneurysm and enter the blood vessel, so the part that has exceeded this limit is displayed in a fourth color. The length of the device after deformation can be calculated by determining the diamond shape from the circumference of the annular part. <Effects of configuration 4 and below> The length of the device along the centerline after insertion into the cerebral aneurysm can be calculated, and an accurate image of the device inserted inside the cerebral aneurysm can be drawn. By displaying three-dimensional image data and numerical indicators that reflect the results, it is possible to determine whether the device selection was appropriate. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is an explanatory diagram showing a three-dimensional image of a device inserted into a cerebral aneurysm and the image divided into rings. [Figure 2]FIG. 2 is a side view showing examples of various types of devices. [Figure 3] FIG. 3 is an explanatory diagram showing the envelopes of three types of devices. [Figure 4] Figure 4 shows a comparison of the state of three types of devices inserted into a cerebral aneurysm. [Figure 5] FIG. 5 is an explanatory diagram of coloring according to the positional relationship between the annularly divided device and the cerebral aneurysm. [Figure 6] FIG. 6 is an illustration of an example where the device extends beyond the neck plane. [Figure 7] Figure 7 shows longitudinal cross-sectional views of devices with different shapes and cerebral aneurysms. [Figure 8] FIG. 8 is an explanatory diagram showing the relationship between the outer diameter and width of the device inserted into the cerebral aneurysm. [Figure 9] FIG. 9 is an explanatory diagram of the relationship between the outer diameter of each part of the device and the width of the ring. [Figure 10] FIG. 10 is an illustration of an expanded image of the device inserted into a cerebral aneurysm. [Figure 11] FIG. 11 is an illustration of an image of the device inserted into a kinked cerebral aneurysm. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described in detail for each example. [Example]

[0014] As shown in Figure 1, the present invention aims to display a three-dimensional image of a device 14 inserted into a cerebral aneurysm 12 using computer simulation, and to assist in selecting a device 14 for treating the cerebral aneurysm 12 and in planning treatment.

[0015] In the present invention, a three-dimensional image is displayed of a device 14 inserted into a cerebral aneurysm 12, the device 14 being made of a self-expanding elastic braid that expands without the application of external force. The braid of the device 14 is configured so that the entire device is surrounded by a diamond-shaped mesh using thin lines, as shown in the figure. As shown in Figure 1(a), the three-dimensional image of the device 14 and cerebral aneurysm 12 is divided by a cross section 18 that passes through the vertices of each diamond and is perpendicular to the center line 16 of the device 14. In the example shown in this figure, this divides the device into rings of approximately the same thickness.

[0016] In this way, the positional relationship between the envelope of the divided device 14 (device ring 20) and the inner wall of the cerebral aneurysm 12 (aneurysm ring 22) is determined. As shown in Figure 1(b), the device ring 20 is cut by a plane perpendicular to the center line 16. The aneurysm ring 22 is also cut at the same thickness as the cerebral aneurysm 12. If we focus only on this part, the device 14 appears to be fitted inside the cerebral aneurysm 12 with a gap between them. Therefore, the positional relationship between the two is quantified, and the result is displayed as a colored three-dimensional image of the cerebral aneurysm 12.

[0017] In this case, it is conceivable to display a three-dimensional image of the state after device 14 has actually been inserted inside cerebral aneurysm 12 and calculate the gap that occurs between them, but as will be explained later, the shape of each part of device 14 may be deformed when inserted into cerebral aneurysm 12. Finding the coordinate values ​​of the outer shape and accurately calculating the relationship with the inner wall of cerebral aneurysm 12 is a complicated process.

[0018] Therefore, here, we assume that the device 14 is inserted into the cerebral aneurysm 12 without any external force being applied, and calculate the positional relationship using coordinate data that is clear from the structure of the device 14. If the device expands without any external force being applied, it will have the shape as designed, so standard calculation processing is possible.

[0019] As described above, the braided body of the device 14 is a collection of diamond-shaped stitches 14a as shown in Figure 1(c). When an external force is applied by colliding with the wall of the cerebral aneurysm 12, the diamonds 14a are stretched and deformed in the horizontal and vertical directions. This causes the coordinate values ​​at the time of design to fluctuate. Therefore, in the simulation for device selection, calculations were performed without the application of external force.

[0020] As shown in FIG. 2, device 14 is available in a variety of shapes and sizes. Each device is composed of a self-expanding elastic braid, as described in Patent Documents 1 and 2, and is drum-shaped or tubular, with the entire device surrounded by diamond-shaped stitches. In computer simulations, a three-dimensional image of device 14 is displayed using a virtual semi-transparent envelope surface indicated by a dashed line, as shown in FIG. 3. That is, the shape of device 14 is displayed using an envelope surface, and the image is displayed semi-transparently to allow the cerebral aneurysm 12 to be seen through.

[0021] Although the center line 16 of the cerebral aneurysm 12 is not necessarily a straight line, the state in which the device 14 is inserted is set so that part of the center line 16 coincides with the center line 16 of the device 14. In the example of Figure 1, the center lines of both devices are nearly overlapping. Figure 4 shows a diagram assuming that the three types of devices 14 shown in Figure 3 have been inserted into the same cerebral aneurysm 12.

[0022] The example in Figure 4(a) shows a case where the device 14 is too large for the cerebral aneurysm 12. The example in Figure 4(b) shows a case where a device 14 of approximately the same size as the cerebral aneurysm 12 is inserted. The example in Figure 4(c) shows a case where a device 14 that is too small for the cerebral aneurysm 12 is inserted. In both examples, a plan view of the device ring 20 and the aneurysm ring 22 with a portion cut away is shown on the right. In the examples in Figures 4(b) and (c), a gap has formed between the device ring 20 and the aneurysm ring 22. While it is acceptable if the width of this gap is within a certain tolerance, if the gap exceeds the tolerance, blood may flow into that area and cause the cerebral aneurysm 12 to rupture. In practice, this tolerance is approximately 1 mm.

[0023] As already explained using Figure 1, by dividing the device 14 equally along a plane perpendicular to the center line and passing through the vertices of the diamond-shaped mesh, a group of rings with a thickness equivalent to half the vertical length of the diamond was obtained within the set range (almost the entire area in this example). The actual device size is often 5 to 10 mm in width and 4 to 11 mm in the center line direction. Therefore, it is recommended to divide the device into thicknesses of approximately 0.2 to 0.8 mm.

[0024] Here, as shown in Figure 5, the positional relationship between each ring 20 of the device 14 and each ring 22 of the cerebral aneurysm 12 is compared. First, the ring 20 of the device and the ring 22 of the cerebral aneurysm 12 are divided into multiple parts at a fixed central angle 24 as viewed from the center line 16. It is also advisable to use the coordinates of the vertices of a diamond for this division.

[0025] This yields the segment 26 of the ring of the cerebral aneurysm 12 and the segment 28 of the ring of the device 20. The distance between each segment group is calculated, and finally the segment 26 of the ring 22 of the cerebral aneurysm 12 is colored. Alternatively, the ratio of the cross-sectional areas of the ring 20 of the device 14 and the ring 22 of the cerebral aneurysm 12 may be calculated, and whether the gaps are sufficiently filled overall may be displayed by color, and also indicated by a numerical index, volume filling rate, or surface contact rate.

[0026] In this example, the annulus 22 of the divided cerebral aneurysm 12 is divided into a plurality of segments 26, and each segment 26 is colored according to its positional relationship. For example, when the envelope of the device 14 is positioned so that it sinks into the inner wall of the cerebral aneurysm 12 by a certain amount or more, the segment is displayed in a first color (red); when the envelope of the device 14 is positioned so that it just touches the inner wall of the cerebral aneurysm 12, the segment is displayed in a second color (white); and when the envelope of the device 14 is positioned so that a gap of a certain amount or more is created between the envelope of the device 14 and the inner wall of the cerebral aneurysm 12, the segment is displayed in a third color (blue). In this way, by displaying the segments in at least three easily recognizable colors, the relationship between the two segments becomes clear.

[0027] In the plan view of the device annulus 20 and the aneurysm annulus 22 shown in Figure 5, a portion of the device annulus 20 extends outside the aneurysm annulus 22. In reality, the device annulus 20 collides with the inner surface of the aneurysm annulus 22, preventing expansion of this portion. The device 14 does not push the aneurysm annulus 22 apart. As a result, the perimeter of the device annulus 20 in this portion becomes smaller than the designed perimeter. The relationship between the perimeter of the device annulus and the perimeter of the cerebral aneurysm annulus affects the device's holding force in this portion. Therefore, it is advisable to convert this to holding force, for example, and output a numerical indicator.

[0028] At this time, the diamond shape shown in Figure 1(c) extends in the direction of the center line at this point. This causes the device to extend in the direction of the center line, and as shown in Figure 6, for example, part of the device may extend below the neck plane 30 of the cerebral aneurysm 12. In the above example, the relationship between the cerebral aneurysm 12 and the device 14 is displayed when no external force is applied to the device 14. On the other hand, after a candidate device of appropriate size and shape is found, it is advisable to calculate the results when part of the device 14 actually deforms as shown here. That is, after performing the calculation described in Figure 5 and coloring, the part colored in the first color is changed to the second color, and the extension in the direction of the center line is calculated. When the neck plane 30 of the cerebral aneurysm is exceeded, part of the cerebral aneurysm 12 in this part and part of the blood vessel 32 around the neck plane 30 can be colored in a fourth color (black) to draw attention.

[0029] In other words, even if the size of the device 14 to be inserted into the cerebral aneurysm 12 is selected appropriately, the results of insertion may not necessarily be optimal. Therefore, it is desirable to display multiple simulation results by changing the device position and degree of deformation, in order to select the best device and develop a treatment plan. The simulator of the present invention can flexibly meet such requirements. [Example]

[0030] Figure 7 shows a perspective view of the device envelope, and above that is a cross-sectional view of the device inside a cerebral aneurysm. Cerebral aneurysms come in various shapes, and the device is prevented from expanding at each part of the aneurysm, resulting in a deformed shape. Because the device is surrounded by braided wire, its cross section is approximately circular or elliptical.

[0031] When a device is inserted into a cerebral aneurysm, if there are portions of the device where expansion is prevented by the inner wall of the cerebral aneurysm, the length of the device will increase in the direction of the centerline. In this example, an image of the device actually inserted into the cerebral aneurysm is drawn together with an image of the cerebral aneurysm. As in Example 1, the three-dimensional image of the cerebral aneurysm is colored to distinguish between appropriate and inappropriate positional relationships between the device ring and the cerebral aneurysm ring.

[0032] In Figure 8(a), when device 14 is inserted into cerebral aneurysm 12, the area indicated by the thick line is the area where device 14 was not fully expanded. When the area is divided into three, A1, A2, and A3, as shown in the figure, the perimeter of device 14 is shorter in areas A2 and A3. The state in which device 14 is expanded without the application of external force will be referred to as the initial state for the remainder of the explanation.

[0033] The left side of Figure 8(b) is a plan view of a portion of the mesh of the device when it is expanded without the application of external force. To the right of that is a plan view of the mesh when the perimeter has been shortened. Figure 8(c) shows the relationship between the length of this mesh in the direction of the device's center line and the perimeter of that portion of the device. The length c of one side of the diamonds that make up the mesh is constant at any point on the device. The total number of diamonds counted around the device is also constant. From this, as shown in the figure, the relationship between the perimeter of the device and the width in the direction of the center line of that portion can be expressed by a constant relationship.

[0034] As shown in Figure 9, a device in an expanded state without external force is divided into n pieces in a cross section perpendicular to its centerline. The number of divisions and the width of the divisions can be arbitrary. For example, the width may be the width of one diamond (bx2 in Figure 8) or the width of several diamonds. The number of diamonds around one circumference of the device 14 is constant, P. The perimeter of each obtained circle is then defined as Lm (m = 1 to n), and the width of each circle as viewed in the direction of the centerline of the device is defined as wm (m = 1 to n). The relationship between the perimeter Lm and the width wm in the direction of the centerline can be expressed as wm = f(Lm).

[0035] In other words, in the example shown in the figure, the device in its expanded state is made up of three connected rings: one with a circumference of L1 and a width of w1, one with a circumference of L2 and a width of w2, one with a circumference of L3 and a width of w3, one with a circumference of L4 and a width of w4, and one with a circumference of L5 and a width of w5. If the device is drum-shaped, the widths of the rings will be slightly different.

[0036] When the device is inserted into the cerebral aneurysm 12, the circumferential length of the portion that is not fully expanded shortens, and the width expands accordingly. For example, when the outer diameter of a ring with a circumferential length of L1 and a width of w1 is reduced, the outer diameter L1' and width w1' after deformation satisfy the relationship w1 = f(L1).

[0037] The image data is used to measure how much the outer diameter of each of the n rings (five in the example shown) of the device inside the cerebral aneurysm has been reduced. For example, the diameter of the rings of the device can be measured and calculated from that. The circumference is then substituted into each equation to calculate the new width of each ring. The widths of all the rings are then added together.

[0038] That is, when the N=1 ring is deformed, the post-deformation width w1 is calculated using the relational expression w1 = f(L1). When the N=2 ring is deformed, the post-deformation width w2 is calculated using the relational expression w2 = f(L2). When the N=3 ring is deformed, the post-deformation width w3 is calculated using the relational expression w3 = f(L3). When the N=4 ring is deformed, the post-deformation width w4 is calculated using the relational expression w4 = f(L4). When the N=5 ring is deformed, the post-deformation width w5 is calculated using the relational expression w5 = f(L5).

[0039] From the results of this calculation, w1 + w2 + w3 + w4 + w5 is the length along the centerline of the device after it has been inserted into the cerebral aneurysm. Note that the above calculation was made because the outer diameters of each part of the drum-shaped device are not the same in the initial state. If an approximate calculation does not result in a large error, a fixed relationship can be used regardless of the initial shape of the device.

[0040] When a device is inserted into a cerebral aneurysm, if there are areas of the inner wall of the cerebral aneurysm where expansion is hindered, the device will always be stretched longer than its original size and fit inside the cerebral aneurysm 12. Using the position data of all the annular rings obtained in this way, it is possible to draw an image of the device when it is actually inserted inside the cerebral aneurysm. At the same time, it is possible to display numerical indicators, volume filling rate, or surface contact rate.

[0041] For example, by calculating the width of the ring furthest from the blood vessel and connecting the rings with the width of adjacent rings in order, it is possible to accurately depict the shape of a device with a portion extending toward the centerline inside the cerebral aneurysm 12. If the number of divisions n is large, it is possible to depict a device with a smooth outline. If it is desired to fix the position of a specific ring at a specific location on the cerebral aneurysm 12, it is sufficient to connect adjacent rings in order from that ring. The position data for each ring can be expressed as the position coordinates of the top and bottom surfaces of the ring. By displaying three-dimensional image data reflecting the results, it is possible to determine whether the device selection was appropriate.

[0042] Furthermore, by using the method of Example 1 to display a colored three-dimensional image of a cerebral aneurysm, it is possible to distinguish between appropriate and inappropriate positional relationships between all the annulus of the device and the annulus of the cerebral aneurysm surrounding it. Furthermore, it is possible to display the positional relationship between the device inserted inside the cerebral aneurysm and the nearby blood vessels, as explained in Figure 6. By displaying the results in colored three-dimensional images of the cerebral aneurysm and the blood vessels, it is possible to distinguish between appropriate and inappropriate device insertion.

[0043] Figure 11 shows an example in which a device 14 is inserted into a bent cerebral aneurysm 12. Here, the center line of the cerebral aneurysm 12 and the center line of the device 14 are assumed to be nearly overlapping. Even in this case, if the center line 16 is divided into predetermined intervals and the device 14 is cut along a plane perpendicular to the center line 16, calculations similar to those in the above example can be performed.

[0044] Figure 11(a) shows an example in which the perimeter of each part of device 14 remains almost constant throughout its entire length. If device 14 shown in this figure is cut in two places in a cross section perpendicular to centerline 16, a circular ring is obtained in which the bending portions are deformed and the thickness of each portion is uneven. However, no matter how this ring is deformed, as long as the perimeter of the ring is constant, the thickness of the centerline portion will be constant. In other words, even if the device as a whole is bent inside cerebral aneurysm 12 as shown in the figure, the thickness of the centerline portion of the ring can be calculated using the above calculation. By adding these values ​​in order, the entire length of device 14 can be determined.

[0045] As shown in Figure 11(b), when the perimeter of a portion of the device 14 is shortened by the inner wall of the cerebral aneurysm 12, the thickness of the entire ring increases when that portion is cut in a cross section perpendicular to the center line 16. In this example, too, the total length of the device can be found by sequentially adding up the thicknesses of the rings along the center line 16. Starting from the ring furthest inside the cerebral aneurysm 12 (the ring at the top of the figure), the thicknesses are calculated and the rings are drawn one by one, and finally an envelope of these rings is created, allowing an image of the device 14 fitted inside the bent cerebral aneurysm 12 to be drawn. [Explanation of symbols]

[0046] 12 Cerebral aneurysm 14 devices 16 Center line 18 Cut surface 20 Device Circle 22 The Circle of Ru 24 center angle 26 Fragment of Ru 28 Device Fragments 30 Neck plane 32 Blood vessels

Claims

1. A computer simulator for planning treatment of cerebral aneurysms, which displays a three-dimensional image of a device inserted into a cerebral aneurysm, the device being made of a self-expanding elastic braid that expands without the application of external force, divides the three-dimensional image of the device and cerebral aneurysm into multiple annular sections along a cross section that passes through the vertices of the diamond-shaped braid that makes up the device's braid and is perpendicular to the center line of the device, determines the relationship between the envelope of the divided device and the inner wall of the cerebral aneurysm, and displays the result in color on the three-dimensional image of the cerebral aneurysm.

2. 2. A computer simulator for treatment planning for cerebral aneurysms as described in claim 1, characterized in that the divided cerebral aneurysm ring is divided into a plurality of segments, and for each segment, the segment is displayed in a first color when the envelope of the device is in a positional relationship such that it exceeds the inner wall of the cerebral aneurysm, the segment is displayed in a second color when the envelope of the device is in a positional relationship such that it just contacts the inner wall of the cerebral aneurysm, and the segment is displayed in a third color when the envelope of the device is in a positional relationship such that a gap of a certain amount or more occurs between the envelope of the device and the inner wall of the cerebral aneurysm.

3. 2. A computer simulator for treatment planning for cerebral aneurysms as described in claim 1, characterized in that when the envelope of the device is positioned so as to extend beyond the inner wall of the cerebral aneurysm, the inner wall of the cerebral aneurysm prevents the radial expansion of the device, and when the length of the center line of the device exceeds the length of the center line when expanded in the absence of external force and reaches from the neck plane of the cerebral aneurysm into the blood vessel, the exceeding portion is displayed in a fourth color.

4. A device in an expanded state without external force is divided into n pieces in a cross section perpendicular to its centerline, and the circumferential length of each of the obtained rings is defined as Lm (m = 1 to n), and the width of each ring as viewed in the direction of the centerline of the device is defined as wm (m = 1 to n). A relational expression wm = f(Lm) that shows the relationship between the circumferential length Lm of the ring and its width wm is obtained, When a device is inserted into a cerebral aneurysm, if there are areas of the inner wall of the cerebral aneurysm that are prevented from expanding, The amount by which the circumference of each of the n annulus of the device in the cerebral aneurysm has decreased from the original circumference Lm is measured from the image data, and the new width of each annulus is calculated using the above relational expression and cumulatively added. A method for calculating the length along the centerline of a device within a cerebral aneurysm.

5. A computer simulator for treatment planning of cerebral aneurysms, characterized in that it uses position data of all the annuli obtained by the method of claim 4 to draw an image of a device actually inserted inside the cerebral aneurysm.

6. A computer simulator for planning treatment of cerebral aneurysms, characterized in that it displays in color a three-dimensional image of a cerebral aneurysm all of the annulus of a device obtained by the method of claim 4 and the annulus of the cerebral aneurysm around it, in order to distinguish between appropriate and inappropriate positional relationships.

7. A computer simulator for planning treatment of cerebral aneurysms, characterized in that it displays in color a three-dimensional image of the cerebral aneurysm, obtained by the method of claim 4, a positional relationship between a device inserted inside the cerebral aneurysm and nearby blood vessels, so that it is possible to distinguish between appropriate and inappropriate cases.

8. 8. A computer simulator for planning treatment for cerebral aneurysms according to claim 6 or 7, wherein the three-dimensional image of the cerebral aneurysm is colored and a numerical index, a volume filling rate, or a surface contact rate is displayed.

Images