JPH0970405A - Cerebral aneurysm clip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of a large distortion in an image by composing the blades of a cerebral aneurysm clip of zirconia. SOLUTION: The blades 1, 1 of the clip C are composed of the zirconia and, therefore, the large distortion does not arise in the image at the time of NMR-CT inspection and, consequently, hindrances do not arise. Namely, the zirconia does not induce halation even in a high magnetic field and at high frequency. Further, the blades 1, 1 of the clip C consist of the zirconia and, therefore, the clip has the high mechanical strength and toughness thereby the miniaturization thereof is possible. The zirconia ceramic has relatively high elasticity only when the zirconia ceramic is made into a thin and slender shape. The constricted parts 3, 3 of the blood vessel are opened by pressing a U-shaped clamping part 8 by a clamp. The constricted parts 3, 3 of the blood vessel are closed when this pressing state is next released.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cerebral aneurysm clip, and more particularly to an NMR-C for a patient wearing this clip.
The present invention relates to a ceramic cerebral aneurysm clip that enables avoidance of obstacles during T examination.

[0002]

Cerebral aneurysm is a cerebral artery swelling in the shape of an aneurysm, and if it ruptures, it causes subarachnoid hemorrhage and becomes very dangerous when it affects human life.

Surgery for a cerebral aneurysm begins with X as angiography.
It is performed after its existence is confirmed by line CT, NMR-CT, etc., and is completed by sandwiching the root of the aneurysm with a special clip called a cerebral aneurysm clip. After the surgery, the clip will remain in the body.

Conventionally, this cerebral aneurysm clip has been made of stainless steel or a metal such as a cobalt-chromium alloy. However, in X-ray CT, when a subject contains a metal or the like, X-rays are reflected / scattered on the surface of the subject, which causes halation in a captured image, making it virtually impossible to read the inspection result. Further, since NMR-CT uses a strong magnetic field and high frequency, if a magnetic substance is present in the subject, a large amount of distortion will occur in the image, and heat generation of the clip will occur in the body. Furthermore, there is a problem that due to the presence of a metal having conductivity, an induced current is generated in a magnetic field and a high frequency field, which poses a danger to the human body. Patients who have surgery for a cerebral aneurysm and have a metal clip in the brain After surgery, X-ray CT or N plays an important role in brain surgery such as cerebral aneurysm surgery
He was having trouble getting the MR-CT examination.

In order to solve these problems, X of alumina, AlN, sialon, silicon nitride, silicon carbide, etc. is used.
A cerebral aneurysm clip made of ceramics having an HN value of line CT of 2500 or less has been proposed. (Tokuhei 3-6065
(See 2, Ibid. 5-9101, Ibid. 5-54985)

[0006]

By the way, in recent years, NMR is mainly used for examinations that play a very important role in brain surgery such as cerebral aneurysm surgery.
-CT examination is used.

Cerebral aneurysm clips made of ceramics having an HN value of X-ray CT of 2500 or less proposed in JP-B-5-9101 and JP-A-5-54985 place emphasis on antihalation measures in X-ray CT examination. , NMR-
For CT examination, its validity is considered only because it is a non-magnetic material. Therefore, even if ceramics such as alumina, AlN, sialon, silicon nitride, and silicon carbide having an HN value of X-ray CT of 2500 or less as described above, N
A large distortion may occur in the image at the time of MR-CT examination, and there is a risk of causing trouble during the NMR-CT examination as in the case of the metallic cerebral aneurysm clip.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems of the prior art and to provide a cerebral aneurysm clip that does not interfere with post-operative NMR-CT examination.

[0009]

Therefore, experiments were repeated on various ceramic materials for the presence or absence of halation failure during NMR-CT inspection and the size thereof, and zirconia is the most resistant to halation failure for NMR-CT inspection. The material was identified and the blade was constructed from zirconia in a cerebral aneurysm clip.

Incidentally, Japanese Patent Publication No. 5-54985 describes that zirconia has an HN value of X-ray CT of 9000 and is not suitable as a material for a cerebral aneurysm clip.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a cerebral aneurysm clip (hereinafter, abbreviated as clip) C according to the present embodiment, and the clip is composed of a pair of blades 1 and 1 arranged opposite to each other made of zirconia. 1, 1 are integrally combined by a connecting member 2 made of a polymer material, and an annular body 4 made of an elastic material such as silicon rubber is fitted around the blood vessel holding portions 3, 3 at the tips. The blood vessel holding portions 3, 3 are opened by pressing the rear end side gripping portions 5, 5 with forceps (not shown), and when the pressed state is released next, the blood vessel holding portion is urged by the annular body 4. 3 and 3 are closed.

FIG. 2 shows the above-mentioned connecting member 2, which is a substantially cylindrical body having a bottom with one end open, and notches for assembling the blades 1 and 1 at two opposite side surfaces thereof. 6 and 6, a swing shaft 7 having a stopper head 7a is provided in the axial direction of the cylindrical body. Therefore, the blades 1, 1 can be held openably and closably.

Such a clip C includes blades 1 and 1
Is composed of zirconia, NMR-CT
No large distortion occurs in the image during inspection, so NM
There is no problem during R-CT examination. This is because, as will be described later, zirconia is a material that does not cause halation even in high magnetic fields and high frequencies.
Furthermore, since the blades 1 and 1 of the clip C are made of zirconia, they have a large mechanical strength and toughness and can be miniaturized.

FIG. 3 shows a clip C made of zirconia according to another embodiment. The U-shaped grip portion 8 formed integrally with the blades 1 and 1 has a thickness at the apex of the U-shape that is 0.1 to 0.6 times the thickness of the other portions. It has a spring function and urges both ends in the opening direction. Reference numeral 9 is an intersecting portion, and both ends of the U-shaped grip portion 8 intersect each other in an X shape, and one of them passes through the through hole 10 of the other.

It is generally known that zirconia ceramics has a relatively large elasticity only when it has a thin and elongated shape. This is because zirconia ceramics has a smaller elastic modulus than other ceramics. In the case of the above-mentioned clip C, the U-shaped grip portion 8 has a thin and elongated shape, and the thickness of the central portion is made extremely small as compared with the both end portions so as to have appropriate elasticity.

In FIG. 4, both ends of the U-shaped gripping portion 8 intersect in an X-shape at the intersections 9 and 9 in the clip C shown in FIG. Since the U-shaped gripping portion 8 is pressed by forceps (not shown) by providing the blood vessel holding portions 3 and 3 at the target position, the blood vessel holding portions 3 and 3 are opened. It is supposed to close.

In the production of the clip C shown in FIGS. 3 and 4, the zirconia slurry is molded and hardened by the injection method, and then the blood vessel holding portions 3, 3 and the crossing portion 9,
A method of polishing the obtained sintered body by performing a sintering prevention treatment with powder or sheet-like powder on the opposing portions such as 9 and then firing at about 1400 to 1500 ° C. was used. In addition, a casting method can be used as the molding method.

FIG. 5 shows a clip C according to another embodiment. The pair of blades 1 and 1 arranged to face each other are slidably engaged by a connecting member 16 made of zirconia or a polymer material, and a plate-shaped spring member 13 made of zirconia is attached to the grip portions 5 and 5. By being joined, the gripping parts 5, 5 are urged in the opening direction, and as a result, the blood vessel holding parts 3, 3 are closed with the engaging part 12 as a fulcrum.

Further, the plate-shaped spring member 13 is devised so as to have appropriate elasticity by making the thickness of the central portion extremely smaller than the thickness of the both end portions thereof, so that the spring property is imparted. It is a thing.

The clip C shown in FIG. 6 is the clip C shown in FIG.
The engaging portion 12 in is engaged by the slidable concavities and convexities 14 and 14 provided at the positions where the blades 1 and 1 face each other.

FIG. 7 shows the plate-shaped spring member 13 of the clip C shown in FIGS.
The coiled spring member 15 has a core diameter of 0.5.

In manufacturing the clip C shown in FIGS. 5 and 6, a plate-shaped spring member 13 separately formed by an injection method or a casting method at a position opposite to the blades 1, 1 formed by an injection method or a casting method, or After joining the coil-shaped spring member 15 with the zirconia slurry, the engaging portion 12 and the blood vessel holding portions 3, 3 and the like are subjected to a sintering prevention treatment with powder or sheet-shaped powder and then about 1
A method of firing at 400 to 1500 ° C. and polishing the obtained sintered body was used.

Experimental Example 1 Pure titanium, Ti-6Al-4 as described in Table 1.
V, Vitalium, SUS316L, Single crystal alumina,
7 kinds of high-purity alumina and zirconia are used.
A test piece having a size of × 1 × 20 was prepared.

Next, these test pieces were held in agar, and MRI images were acquired at 1.5 Tesla. Then, in the obtained images (photographs), the degree of artifacts was compared for each material type. Table 1 shows the results.

[0025]

[Table 1]

As is clear from Table 1, zirconia is NM
Halation did not occur on R-CT.

Experimental Example 2 Various materials were tested for MRI images. A zirconia, silicon nitride, silicon carbide, alumina, single crystal alumina, pure titanium, titanium alloy, SUS316, vitalium, and SUS631 material was used to form a 1 × 2 × 20 mm prismatic test piece, which was embedded in agar. The thing was made into the test body.

These test specimens were photographed by MRI at 1.5 Tesler, and the images were compared on a film.
Zirconia was most clearly reflected, followed by silicon nitride, silicon carbide, alumina, and alumina single crystals, and the images were slightly disturbed by titanium and titanium alloys, and the images were clearly crushed by 316SUS and vitalium. Since SUS631 is a magnetic substance, it jumped out of the agar during shooting.

[0029]

As described above, according to the present invention, since the blade is made of zirconia in the cerebral aneurysm clip, the image is not greatly distorted during the NMR-CT examination, and therefore the trouble occurs during the NMR-CT examination. Never. Furthermore, since the blade of the clip is made of zirconia, it has an excellent effect that it has large mechanical strength and toughness and can be miniaturized. Further, when all the members are made of zirconia, it does not use any other material that may be harmful to the body, corrode, or wear, and therefore has an excellent effect of being extremely safe for the body. Is.

[0030]

[Brief description of drawings]

FIG. 1 is a perspective view of a cerebral aneurysm clip according to one embodiment of the present invention.

2A is a perspective view of a connecting member that constitutes the cerebral aneurysm clip of FIG. 1, and FIG. 2B is a cross-sectional view taken along line xx thereof.

FIG. 3 is a perspective view of a cerebral aneurysm clip according to another embodiment of the present invention.

FIG. 4 is a perspective view of a cerebral aneurysm clip according to another embodiment of the present invention.

FIG. 5 is a perspective view of a cerebral aneurysm clip according to another embodiment of the present invention.

FIG. 6 is a perspective view of a cerebral aneurysm clip according to another embodiment of the present invention.

7 (a) is a plan view of a plate-shaped clip of the cerebral aneurysm clip of FIG. 6 used as a coil-shaped spring member, and FIG. 7 (b) is a plate-shaped clip of the cerebral aneurysm clip of FIG. It is a top view of what was made into the shape of a spring member.

[Explanation of symbols]

 C (cerebral aneurysm) clip 1 blade 2 connecting member 3 blood vessel holding portion 4 annular body 5 gripping portion 6 notch 7a stopper head 7 swinging shaft 8 U-shaped gripping portion 9 crossing portion 10 through hole 12 engaging portion 13 spring Member 14 Concavo-convex 15 Spring member 16 Connecting member

Claims (1)

[Claims] 1. A cerebral aneurysm clip comprising a blade for stopping bleeding of capillaries in brain surgery, wherein the blade is made of zirconia.