JPH06165769A - Surgical tool fitted to magnetic resonance photographing method - Google Patents

Abstract

PURPOSE: To make it possible to carry out a surgical treatment without causing any distortion of MR-image, and to obtain a dialogue-type imaging by making a surgical instrument from a ceramic material having a stable, small magnetizing rate and high intensity, and which is stabilized by yttria or magnesia. CONSTITUTION: A surgical instrument is made from a ceramic material stabilized by yttria and magnesia, and having a smaller magnetizing rate with a high intensity. As the surgical instrument, a bio-testing needle and a small knife are formed, for example. As the bio-testing needle a canuula 2 having a lure lock joint 4, a central opening 5 and a sharp blade tip 11, is inserted into a living body by using a positioning 6 and a sleeve 8. A drug solution is injected from the central opening 5, for example, the part of a body fluid or bionic tissue is extracted. The knife consists of a very thin blade 15 and a stem 17, and used for an incision. These surgical instruments are composed of a material having a small magnetizing rate. By this, a surgical treatment is conducted during the magnetic resonance imaging without any trouble, and a dialogue-type internal imaging is produced and displayed during the surgical operation.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to surgical instruments and, more particularly, to surgical instruments that can be used in magnetic resonance imaging.

[0002]

2. Description of Related Art Surgical instruments such as swords (or scalpels) and biopsy needles are usually easily sterilizable, have a high degree of rigidity, and are critical when inserted into the body of a subject. It is made of a material (usually stainless steel) that does not cause physiological side effects. Several alloys are known as suitable materials for making such surgical instruments.

Magnetic resonance (MR) imaging uses large magnets for producing a uniform magnetic field and gradient coils for uniformly varying the magnetic field in time or space to produce a magnetic field gradient. It MR imaging also uses an RF coil to apply a radio frequency (RF) electromagnetic field to the tissue to be imaged, thereby causing the tissue to resonate and generate an MR response signal. An image is created using the MR response signal thus obtained. The homogeneity of the magnetic field and the linearity of the magnetic field gradient in space are important for obtaining a clear image without distortion. Interference with RF fields also reduces the quality of the images obtained.

Recently, it has been desired to obtain interactive images of the patient's internal organs during surgery. The use of MR imaging is advantageous because it produces very detailed images of soft tissue. The best imaging results are then obtained if the magnetic and RF fields generated by the MR imager are not disturbed by the surgical instrument. Many metals have ferromagnetism and are therefore physically attracted to magnets. Due to the strong magnetic fields used in MR imaging, the instrument may be subjected to large magnetic forces. Therefore, the penetrating device must not be made of ferromagnetic material. Otherwise, the magnetic forces applied to the penetrating device make them difficult to operate.

Another problem is observed with materials that produce eddy currents when placed in a variable magnetic field. Eddy currents created in those materials, which are typically conductors, create a unique magnetic field, thereby interfering with the RF fields used for MR imaging. Therefore, materials that produce eddy currents (eg aluminum or copper) should not be used in variable magnetic fields.

Furthermore, the conductor disturbs the RF field required for magnetic resonance imaging and causes its distortion. The degree of magnetization that a material exhibits with respect to an applied magnetic field is defined by the "susceptibility." The magnetic susceptibility of a material also affects the homogeneity of the applied magnetic field within the area surrounding the material. This causes a noticeable distortion in the MR image near the material.

As described above, a surgical instrument which can be used in an MR magnetic field because it is not physically attracted to a magnet which generates an MR magnetic field, and which does not cause distortion in the obtained MR image. Is currently desired.

[0008]

SUMMARY OF THE INVENTION Surgical instruments (such as swords and biopsy needles) made of materials with a low magnetic susceptibility, such as yttria (Y ₂ O ₃ ) stabilized zirconia, have little or no magnet. It is not attracted at all, has only a slight effect on the high-frequency electromagnetic field, does not generate eddy currents and does not affect the homogeneity of the applied uniform magnetic field. Also, such surgical instruments have a high degree of durability and possess a sharp cutting edge. Due to these properties, such surgical instruments have magnetic resonance (M
R) It can be used in the magnetic field used for imaging. As a result, interactive internal images can be created and displayed to the surgeon during surgery.

[0009]

OBJECTS OF THE INVENTION One of the objects of the present invention is to provide a surgical instrument which can be used in a magnetic field for MR imaging without being attracted to the magnet which generates the magnetic field. . Another object of the present invention is to provide a surgical instrument which has a low magnetic susceptibility and thus does not distort the MR image and therefore can be used in the magnetic field of a magnetic resonance imaging apparatus.

Yet another object of the present invention is to provide a surgical instrument which can be used in the magnetic field of a magnetic resonance imaging apparatus without introducing artifacts in the acquired MR image. The features of the invention believed to be novel are set forth with particularity in the appended claims. Nevertheless, the structure and method of implementation of the present invention as well as its additional objects and advantages will be best understood by reading the following description in conjunction with the accompanying drawings.

[0011]

DETAILED DESCRIPTION Turning first to FIG. 1, there is shown a biopsy needle consisting of a cannula 2 having a central opening 5 extending the entire length. Cannula 2 is yttria (Y ₂ O ₃ ).
Stabilized zirconia or magnesia (MgO)
It can be made of a high strength ceramic material such as zirconia stabilized with. The cannula 2 is attached to the luer lock joint 4 and is supported by the positioner 6. The positioner 6 serves to hold the cannula 2 in place so that it can be inserted into the body of a subject. The cannula 2 is slidably fitted to the sleeve 8 of the positioner 6. The cannula 2 also has a sharp tip 11. Such a biopsy needle is inserted into the tissue of the subject by the sharp tip 11 and a small sample is taken in the opening 5. The biopsy needle is then withdrawn from the subject, and the sample retained in the opening 5 is removed for testing. To reduce the invasiveness of such procedures, the biopsy needle is made as thin as possible. This requires that biopsy needles be made of materials that have a high degree of strength and rigidity.

Turning next to FIG. 2, there is shown a sword consisting of a blade 15 supported by a handle 17. Such blade 15
Must be made of a material that can be very thin and possess sharp cutting edges. Handle 1
The material of No. 7 is less important, but needs to have a low magnetic susceptibility. The handle 17 can also be made of a high strength ceramic material as described above (ie, yttria-stabilized zirconia or magnesia-stabilized zirconia).

The materials used to make these surgical instruments must be sterilizable and biocompatible. Biocompatible materials are materials that are non-toxic and do not cause significant physiological side effects. In accordance with the present invention, any instrument that may be needed during surgery based on the requirements described above in connection with biopsy needles and knives (e.g., knives, biopsy needles, fiber optic guides, retractors, Forceps, syringes, catheters and scissors) can be manufactured.

Table 1 below shows the mechanical properties of the above ceramic materials.

[0015]

[Table 1]

In the above table, GPa represents gigapascal and MPa represents megapascal. that's all,
Although the present invention has been described in detail with reference to the preferred embodiments, it will be apparent to those skilled in the art that many other modifications are possible. Therefore, the present invention should be limited solely by the appended claims and should not be construed as limited by the specific conditions or means described for the purpose of illustration herein.

[Brief description of drawings]

FIG. 1 is a plan view of a biopsy needle made of a material having a low magnetic susceptibility according to the present invention.

FIG. 2 is a plan view of a sword made of a material having a low magnetic susceptibility according to the present invention.

[Explanation of symbols]

 2 Cannula 4 Luer lock joint 5 Center opening 6 Positioner 8 Sleeve 11 Sharp tip 15 Blade 17 Handle

Front Page Continuation (72) Inventor Steven Peter Sosa, Lindley Terrace, Williamstown, Massachusetts, USA No. 136 (72) Inventor John Frederick Schenck Schenectady, Carrey, New York, USA Court, 17th (72) Inventor Ronald Dean Watkins Clifton Park Road, Naysayahna, New York, United States, 1584 (72) Inventor Cliftfer Judson Hardy United States, New York, Schenectady, Keys Avenue, number 1403

Claims (7)

[Claims] 1. A surgical instrument, characterized in that it is made of a material that exhibits only a slight magnetization in a magnetic field and is therefore almost not attracted to the magnet of a magnetic resonance imaging apparatus. 2. The surgical instrument of claim 1, wherein the instrument is selected from the group consisting of a knife, biopsy needle, fiber optic guide, retractor, forceps, syringe, catheter and scissors. 3. The surgical instrument of claim 1, wherein the material is sterilizable. 4. The surgical instrument of claim 1, wherein the material is a high strength ceramic material. 5. The surgical instrument of claim 1, wherein the material is yttria (Y ₂ O ₃ ) stabilized zirconia. 6. The surgical instrument of claim 1, wherein the material is magnesia (MgO) stabilized zirconia. 7. The material of claim 1, wherein the material is biocompatible.
The surgical instrument described.