JPH0994235A - Mri medical care system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To always obtaining a clear MR image by providing a means for relatively moving at least one of a receiving coil and a means of formation of magnetic field so that the normal vector of the opening plane of the receiving coil of the MRI apparatus should face in a definite direction to the direction vector of the static magnetic field. SOLUTION: This MRI medical care system comprises a prove 8 inserted in vivo and an MRI apparatus 15 having counter magnets opposing each other and forming a static magnetic field B0 parallel to the ground wherein the MRI apparatus has a receiving unit 10 having a signal receiving coil 2 disposed on the top part of the prove 8. The receiving unit 10 has a ball 13 floated on a liquid contained in a hollow sphere 6. The ball 13 has a heavy under part 13 to always keep the up and down direction. Thereby, the direction vector of the static magnetic field B0 parallel to the ground and the normal vector to the opening plane of the receiving coil 2 are kept always perpendicular to each other and the receiving sensitivity for MR signal by the receiving coil 2 is kept maximal.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an MRI medical system for performing medical treatment while obtaining a tomographic image by an MRI apparatus.

[0002]

2. Description of the Related Art In recent years, nuclear magnetic resonance (hereinafter referred to as MR)
A minimally invasive method for diagnosing a human body using a phenomenon has been developed. The MR phenomenon refers to a phenomenon in which a certain atomic nucleus resonates and absorbs electromagnetic wave energy of a specific wavelength in a magnetic field, and then emits this as an electromagnetic wave. In an MR imaging (hereinafter referred to as MRI) apparatus using this MR phenomenon, The human body is placed in a static magnetic field, a high-frequency magnetic field of a predetermined frequency is applied to the human body to excite nuclei with spin in the human body, and the MR signal of a predetermined frequency generated while the excited nucleus returns to its original state is detected. Then, it is processed by a computer to obtain a tomographic image of the human body.

Generally, such an MRI apparatus has a single cylindrical magnet as a static magnetic field generating means for generating a uniform static magnetic field covering almost the entire human body and a predetermined body for the human body placed in the static magnetic field. R that gives a high frequency magnetic field of the frequency
An F coil, an MR signal detection coil for detecting an MR signal of a predetermined frequency emitted by an excited nucleus having a spin in the human body, and a control unit for processing a detection signal from the MR signal detection coil to obtain a tomographic image of the human body Mainly consists of and.

Recently, in order to reduce the burden on patients such as phobia of closure, an open type in which the above-mentioned single cylindrical magnet (closed type) that covers almost the entire human body is divided into two parts has become widespread. ing. This open type allows the doctor to directly approach the patient through the gap (space) between the two divided magnets, so that simultaneous treatment can be performed while observing the MR tomographic image in real time.

With the widespread use of the open type MRI apparatus capable of performing treatment through the gap (space) between the magnets, the combination of the surgical operation and the MRI apparatus has come to the spotlight. That is, an attempt has been made to perform a surgical operation on a patient from between the divided magnets of the MRI apparatus (US Pat. No. 53680).
No. 32).

[0006]

By the way, the above-mentioned MRI
In some devices, an MR signal detection coil for detecting an MR signal of a predetermined frequency from a human body is built in a magnet together with an RF coil, and another MR signal detection coil is provided separately from the magnet. .

When the MR signal detecting coil is provided separately from the magnet, the gap 7 between the magnets 5 and 5 of the open type MRI apparatus shown in FIG. 1B.
Since the MR signal detecting coil can be arranged at the insertion portion of a medical instrument such as an endoscope or a probe used when performing a treatment through (see JP-A-6-304152,
(JP-A-6-319718, etc.), the MR signal detection coil is moved closer to a target region where MR imaging is desired along with the insertion of a medical instrument into the body, thereby increasing the resolution of the MR image. be able to.

On the other hand, the MR signal receiving sensitivity of the MR signal detecting coil is, as shown in FIG. 1A, the normal vector 3 perpendicular to the opening surface of the detecting coil 2 and the magnets 5 and 5 of the MRI apparatus. It is highest when the direction vector 4 of the static magnetic field B ₀ formed by is perpendicular. In other words, as the magnetic flux of the static magnetic field penetrating the opening surface of the detection coil 2 increases, the reception sensitivity of the MR signal by the detection coil 2 decreases.

Therefore, when the MR signal detecting coil is provided in the insertion portion of the medical device, when the medical device is inserted into the body, the normal vector 3 of the opening surface of the MR signal detecting coil 2 is set.
And the positional relationship between the static magnetic field B _{0 and} the direction vector 4 constantly change, and accordingly, the sensitivity of the MR signal detecting coil 2 constantly changes. Therefore, the sensitivity of the MR signal detection coil 2 may be lowered depending on the insertion state of the medical device, and the M
Even if the R signal detection coil 2 is brought close to the target site, a good MR image may not be obtained.

The present invention has been made by paying attention to the above circumstances, and an object thereof is to always maintain the sensitivity of an MR signal detecting coil provided in an insertion portion of a medical instrument at an optimum level to obtain a good MR. It is to provide an MRI medical system capable of obtaining images.

[0011]

In order to solve the above-mentioned problems, an MRI medical system of the present invention has an insertion portion that can be inserted into a body, and a receiving coil for receiving a magnetic resonance signal in a living body is inserted. And a static magnetic field generating means for generating a static magnetic field, and obtains a magnetic resonance image in the body based on a magnetic resonance signal from a receiving coil provided in the insertion part of the surgical instrument. The MRI apparatus and the receiving coil and the static magnetic field generating means are arranged such that the normal vector of the opening surface of the receiving coil always faces a constant direction with respect to the direction vector of the static magnetic field generated by the static magnetic field generating means. And a means for relatively moving at least one of them according to the insertion direction of the insertion portion of the medical device.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows a first embodiment of the present invention. As shown in FIG. 2B, the MRI medical system according to the present embodiment includes a probe 8 as a medical device to be inserted into the body and an open magnet type M.
The RI device 15 is provided.

As shown in FIG. 1B, the MRI apparatus 15 is provided with counter pole type magnets 5 and 5 which face each other and form a static magnetic field parallel to the ground. Magnets 5, 5
Is a permanent magnet, a superconducting magnet, or a normal conducting magnet. Further, the magnets 5 and 5 give spatial information to a magnetic resonance signal (hereinafter referred to as MR signal) and an RF coil that gives a high frequency magnetic field of a predetermined frequency to a human body placed in the static magnetic field. And a gradient magnetic field generating coil for generating a minute gradient magnetic field are provided inside the housing.

The probe 8 is inserted into the human body through the gap 7 between the magnets 5 and 5, for example, and is used to perform a predetermined treatment. At the tip of the probe 8, a receiver 10 including an MR signal receiving coil 2 for receiving MR signals from a living body is provided. MR signal receiving coil 2
Is an MRI for processing an MR signal via a lead wire 11.
The MR signal is electrically connected to the control circuit of the apparatus 15 and can process the MR signal detected by the MR signal receiving coil 2 on the MRI apparatus 15 side to obtain an MR tomographic image of a human body. Specifically, a high-frequency magnetic field having a predetermined frequency is applied to the human body by the RF coil to excite a nucleus having a spin in the human body, and an MR signal having a predetermined frequency generated while the excited nucleus returns to its original state. It is detected by the MR signal receiving coil 2 and processed by a computer to obtain a tomographic image of the human body.

As shown in FIG. 2 (a), the receiver 10 comprises a hollow sphere 6. The inside of the sphere 6 is filled with the liquid 12, and the ball 13 is suspended in the liquid 12. The lower portion 13a of the ball 13 is heavier than the upper portion 13b, and regardless of the orientation of the probe 8 including the receiving unit 10, the vertical relation between the lower portion 13a and the upper portion 13b of the ball 13 is always maintained by gravity. There is. The outer peripheral surface of the ball 13 in which the vertical relationship is always maintained in this manner is parallel to the ground and
The MR signal receiving coil 2 is wound on the surface traversing the outer peripheral surface of the. Therefore, in the MR signal receiving coil 2, since the vertical relationship of the balls 13 is always maintained, the opening surface of the MR signal receiving coil 2 is always parallel to the ground.

According to such a configuration, no matter which direction the probe 8 is inserted into the human body, the ball 13 is rotated by the action of gravity according to the inserting direction, and the ball 13 is rotated.
The vertical relationship between the lower part 13a and the upper part 13b of the MR signal receiving coil 2 is always maintained, and accordingly, the opening surface of the MR signal receiving coil 2 is always parallel to the ground. Therefore, the direction vector 4 of the static magnetic field B ₀ parallel to the ground formed by the magnets 5 and 5 of the MRI apparatus 15 and the normal vector 3 perpendicular to the opening surface of the receiving coil 2 are always kept vertical (FIG. 1). (A)
(See), the receiving sensitivity of the MR signal by the receiving coil 2 is maximized. Thereby, a good MR image can be obtained.

3 and 4 show a second embodiment of the present invention. The MRI medical system of the present embodiment has a probe 20 as a medical device to be inserted into the body.
And an open magnet type MRI apparatus 27.

As shown in FIG. 4, the MRI apparatus 27 has a C-shaped arm 3 rotatably provided with respect to a main body 30.
1 and a counter pole type magnet 5 provided on the arm 31.
5, the direction of the static magnetic field B ₀ can be changed by rotationally driving the arm 31.

As shown in FIG. 3, the probe 20 comprises an elongated insertion portion 21 to be inserted into a body cavity and a main body portion 22 provided on the proximal end side of the insertion portion 21. A step motor 25 is built in the main body portion 22, and an MR signal receiving coil 2 is built in the distal end portion of the insertion portion 21. The MR signal receiving coil 2 is connected to the step motor 2 via the rod 23.
5, the MR signal receiving coil 2 is rotated by the rotation of the rod 23 accompanying the driving of the step motor 25, and the orientation of the opening surface of the MR signal receiving coil 2 can be changed.

The step motor 25 has a controller 26.
The controller 26 controls the drive thereof. The MR signal receiving coil 2 is electrically connected to the control circuit of the MRI apparatus 27 that processes the MR signal via the lead wire 39, and the MR signal detected by the MR signal receiving coil 2 is transmitted to the MRI apparatus 27 side. It is possible to obtain an MR tomographic image of the human body by performing the processing.

At the edge of the opening surface of the MR signal receiving coil 2, a Hall element for detecting the intensity of the magnetic flux of the static magnetic field penetrating the opening surface of the MR signal receiving coil 2 is the same as the opening surface of the coil 2. It is provided on the surface. The detection information from the Hall element is sent to the MRI apparatus 27 to be calculated, and the calculated information is sent to the controller 26. Controller 26
Controls the drive of the step motor 25 based on this calculation information so that the magnetic flux of the static magnetic field formed by the magnets 5 and 5 does not penetrate the opening surface of the MR signal receiving coil 2, that is, the static magnetic field. The receiving coil 2 is rotated so that the normal vector of the opening surface of the receiving coil 2 is perpendicular to the direction vector. That is, the receiving coil 2 is moved according to the inserting direction of the probe 20 so that the normal vector of the opening surface of the receiving coil 2 always faces a constant direction with respect to the direction vector of the static magnetic field, and the magnetic flux of the static magnetic field is moved. Keeps the Hall element clear.

Such an operation is the same when the magnets 5 and 5 are moved by the rotation of the arm 31.
That is, the operation of the receiving coil 2 is controlled according to the change in the direction of the static magnetic field that changes due to the operation of the magnets 5 and 5. That is, the MRI apparatus 27 determines in which direction the static magnetic field formed by the magnets 5 and 5 is oriented.
The controller controls the operation of the receiving coil 2 based on the information detected by the side.

In this embodiment, the rotation operation of the arm 31 is controlled according to the insertion direction of the probe (that is, the direction of the opening surface of the reception coil 2) without controlling the operation of the reception coil 2, and the MR is controlled. The magnetic flux of the static magnetic field may not penetrate the opening surface of the signal receiving coil 2.

As described above, in this embodiment, at least one of the receiving coil 2 and the magnets 5 and 5 is connected to the probe 2.
By moving relative to 0 insertion direction,
Since the direction vector of the static magnetic field formed by the magnets 5 and 5 of the MRI apparatus 27 and the normal vector perpendicular to the opening surface of the receiving coil 2 are always kept vertical (see (a) of FIG. 1), The MR signal reception sensitivity of the coil 2 is maximized. Thereby, a good MR image can be obtained.

By the above-described modes, various configurations shown in the following sections can be obtained. 1. A surgical instrument having an insertion part that can be inserted into the body, a receiving coil for receiving a magnetic resonance signal in the living body being provided in the insertion part, and a static magnetic field generating means for generating a static magnetic field, MR for obtaining a magnetic resonance image in the body based on a magnetic resonance signal from a receiving coil provided in the insertion portion of the instrument
I device and the receiving coil and the static magnetic field generating means such that the normal vector of the opening surface of the receiving coil always faces a constant direction with respect to the direction vector of the static magnetic field generated by the static magnetic field generating means. An MRI medical system comprising: a moving unit that relatively moves at least one of the moving units according to the insertion direction of the insertion portion of the medical device.

2. The moving means includes at least one of the receiving coil and the static magnetic field generating means so that the normal vector of the opening surface of the receiving coil and the direction vector of the static magnetic field generated by the static magnetic field generating means are always perpendicular to each other. The MRI medical system according to claim 1, wherein the MRI medical system is relatively moved in accordance with the insertion direction of the insertion part of the medical device.

3. The magnet of the MRI apparatus generates a static magnetic field parallel to the ground, and the moving means has a lower part that is heavier than an upper part and is floated in a liquid filled in a hollow sphere and its opening surface. The MRI medical system according to claim 1, further comprising an MR signal receiving coil wound around a ball so as to be always parallel to the ground.

4. The MRI medical system according to claim 1 or 2, wherein the medical device is an endoscope. 5. The MRI medical system according to item 1 or 2, wherein the medical device is a probe.

[0029]

As described above, according to the MRI medical system of the present invention, it is possible to always maintain the optimum sensitivity of the MR signal detecting coil provided in the insertion portion of the medical instrument to obtain a good MR image. You can

[Brief description of drawings]

FIG. 1A is a normal vector perpendicular to the opening surface of a detection coil and a static magnetic field B formed by a magnet of an MRI apparatus.
FIG. 3 is a diagram showing a relationship with a direction vector of ₀ , and FIG. 3B is a diagram showing the arrangement of magnets of an open type MRI apparatus.

FIG. 2 is a schematic configuration diagram of an MRI medical system showing the first embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of an MRI medical system showing a second embodiment of the present invention.

4 is a main part configuration diagram of a static magnetic field generating magnet of the MRI medical system of FIG. 3. FIG.

[Explanation of symbols]

2 ... MRI signal receiving coil, 8, 20 ... Probe (medical device), 10 ... Receiving part, 15, 27 ... MRI device, 26
…controller.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Takahashi 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside Olympus Optical Co., Ltd. (72) Ryoji Masuchibuchi 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd. (72) Inventor Katsuya Suzuki 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd.

Claims (1)

[Claims] 1. A medical instrument having an insertion part that can be inserted into the body and provided with a receiving coil for receiving a magnetic resonance signal in the living body in the insertion part, and a static magnetic field generation means for generating a static magnetic field. An MRI apparatus for obtaining a magnetic resonance image in the body based on a magnetic resonance signal from a receiving coil provided in the insertion portion of the surgical instrument; and a normal vector of an opening surface of the receiving coil by the static magnetic field generating means. Means for moving at least one of the receiving coil and the static magnetic field generating means relative to the direction vector of the generated static magnetic field in accordance with the insertion direction of the insertion part of the medical device. An MRI medical system characterized by comprising: