JPH11197131A - Magnetic resonance imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an MRI(magnetic resonance imaging) by which an operator can more easily access a subject body in an open type MRI device using a superconducting magnet. SOLUTION: In this MRI device, magnetic field generation sources 2 provided with a superconducting coil are arranged above and below a photographing area 1 and the magnetic field generation sources 2 generate an uniform magnetic field in the photographing area 1. Magnetic shielding plates 7 are arranged above and below and two yokes 5 are arranged at side around the magnetic field generation sources 2 and a magnetic shield is constituted. By arranging the two yokes 5 behind the photographing area 1, the open property of the device is improved. In such constitution, by setting a height from the standing position 10 of the operator 6 to the center position 8 of the photographing area 1 to 1,000 mmm-1,300 mm, the operator performs IVR work or the like in the photographing area 1 in the posture of tilting forwards.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic resonance imaging apparatus (hereinafter, referred to as an MRI apparatus), and more particularly to an operator (a doctor or a technician performing an inspection work) with improved accessibility to a subject. The present invention relates to an open type MRI apparatus.

[0002]

2. Description of the Related Art Conventionally, a horizontal cylindrical MRI apparatus using a cylindrical superconducting magnet has been widely used. This M
The superconducting magnet used in the RI apparatus is composed of a main coil having a small diameter and a shield coil having a large diameter, and generates a horizontal magnetic field. Usually, since both coils are made using a superconducting wire, a predetermined temperature (for example, a liquid helium temperature (4.
2K) or in the case of oxide superconductors, it is necessary to cool down to the temperature of liquid nitrogen (77 K) to about 10 K). Therefore, the coil is held in a cooling container including a vacuum container, a heat shield, and a refrigerant container (a container for storing liquid helium or the like). Further, in order to keep the temperature low, a refrigerator is used to maintain the temperature of the heat shield at a constant low temperature, or the amount of refrigerant evaporated is reduced.

In an MRI apparatus having such a configuration, a space (imaging area) where a subject enters for imaging is narrow, and the surrounding area is surrounded, so that the subject has a sense of obstruction. For this reason, the subject may sometimes be refused entry into the apparatus. Also, it was difficult for the surgeon to access the subject from outside the device. For these reasons, it has been very difficult to perform an operation (interventional radiology, hereinafter referred to as IVR) under imaging with an MRI apparatus.

In order to compensate for the above-mentioned drawbacks of the horizontal cylindrical type MRI apparatus, a vertical magnetic field type MRI apparatus has been put to practical use. This vertical magnetic field type MRI apparatus is disclosed in Japanese Patent Application Laid-Open No. 2-246927 (known example 1). In the MRI apparatus of the known example 1, a magnetic field source composed of a permanent magnet is disposed above and below an imaging region, and a magnetic shield plate for fixing the magnetic field sources above and below is supported by four yokes. Therefore, the surgeon can access the subject from the front or the rear. However, in the MRI apparatus of the known example 1, it is difficult for the surgeon to access the center of the imaging region because there are four yokes around the MRI apparatus.

[0005] In the vertical magnetic field type MRI apparatus described above, an open type MRI is considered as one in which accessibility to a subject is improved.
The apparatus is disclosed in JP-A-8-140958 (known example 2). In the open-type MRI apparatus of the publicly known example 2, the magnetic field sources are arranged above and below the imaging region, and the upper and lower magnetic field sources are connected by left and right columns, and the imaging region on the front side is opened to the left and right columns. The left and right columns are arranged as shown. With this configuration, the accessibility of the apparatus to the subject from the front side (front and side directions) is remarkably improved.

[0006]

The open type M of the known example 2
In the RI apparatus, FIGS. 9 and 10 show an example in which the operator accesses the imaging region of the apparatus. 9 shows a case where the operator 6 is sitting on a chair or the like, and FIG. 10 shows a case where the operator 6 is standing. However, this open type M
In the RI apparatus, the center of the imaging region 1 from the floor surface 7, that is, the middle point of the cover that covers the imaging region 1 side of the magnetic field sources 2 arranged vertically is at a low position. In the case of FIG. 10 as well, the surgeon 6 can access only the vicinity where the operator is sitting or standing, and it is difficult to access the center of the imaging region 1. In addition, if the operator 6 intends to use both hands while facing the imaging area 1, as shown in FIG.
In R, the surgeon 6 felt great fatigue. Also,
The fact that a bent posture causes fatigue can be found in Kageyu Noro, Illustrated Ergonomics, 280, (Japanese Standards Association, published February 14, 1990) (hereinafter referred to as Document 1).

Japanese Unexamined Patent Publication No. Hei 9-153408 (known example 3) discloses a superconducting magnet device for an MRI device. The superconducting magnet device of the third prior art has a magnetic field source composed of a superconducting coil arranged vertically above and below an imaging region, and is suitable for an open type MRI apparatus. In an MRI apparatus using a superconducting magnet as disclosed in the known example 3, in order to increase the uniformity of the magnetic field formed in the imaging region, the outer diameter of the superconducting coil increases, and accordingly, the outer diameter of the cooling vessel increases. That is, the outer diameter of the magnetic field generation source increases. As a result, the distance between the surgeon on the outer periphery of the magnetic field source and the subject in the imaging region becomes longer, so that the surgeon accesses the subject to perform the IVR operation. Is more difficult to do. Therefore, an object of the present invention is to provide an MRI apparatus in which an operator can more easily access a subject in an open-type MRI apparatus using a superconducting magnet.

[0008]

In order to achieve the above-mentioned object, an MRI apparatus according to the present invention comprises an MRI in which a magnetic field source using a superconductor is provided with a superconducting magnet arranged vertically above and below an imaging region. In the apparatus, the height from the position where the operator can stand to the center of the imaging region is 1,000 mm to 1,300 mm (claim 1).

In this configuration, since the height from the position where the surgeon can stand to the center of the imaging region is appropriate for the surgeon (so-called “ideal height”), the surgeon can shoot. When performing an IVR operation or the like on the subject inserted into the region, the operator can easily access the subject by performing the operation in the forward tilted posture, and without feeling great fatigue. Work can be continued.

In the MRI apparatus of the present invention, the height from the position where the operator can stand to the center of the imaging region is adjusted by providing a stepping board on which the operator stands (claim 2). In this configuration, the step is set around the superconducting magnet, and the surgeon rides on the step, thereby achieving the "ideal height" for the operator. As a result, in the case of claim 1, The same effect can be obtained. This configuration is effective when the height of the upper surface of the magnetic field source below the superconducting magnet is high.

In the MRI apparatus of the present invention, the height from the position where the surgeon can stand to the center of the imaging region is adjusted by providing feet for adjusting the height below the superconducting magnet. (Claim 3). In this configuration, a foot is provided below the superconducting magnet to increase the center position of the imaging region, thereby achieving “ideal height” for the operator. This configuration is effective when the height of the upper surface of the magnetic field source below the superconducting magnet is low.

[0012] In the MRI apparatus of the present invention, the step or the foot is provided with a height changing means, and the height of the step or the foot can be changed by the height changing means. ). In this configuration, the height from the position where the surgeon can stand to the center position of the imaging region can be changed by the step changing means and the height of the foot, so that the height of the surgeon is too high or too low. In this case, the height can be adjusted so that the operator can easily work according to the height of the operator.

In the MRI apparatus according to the present invention, the height from the position at which the operator can stand to the center of the imaging area is adjusted by digging the floor surface at the position at which the operator can stand. ). In this configuration, a hole is dug in the floor surface and the depth is adjusted to optimize the height from the position where the operator can stand to the center position of the imaging region.
This configuration is also effective when the height of the upper surface of the magnetic field generation source below the superconducting magnet is low, as in the case of the third aspect.

In the MRI apparatus of the present invention, the height from the position where the operator can stand to the center of the imaging region is adjusted by embedding a part or all of the superconducting magnet below the floor surface. Claim 6). In this configuration, part or all of the magnetic field source below the superconducting magnet is buried under the floor to lower the center position of the imaging area, achieving "ideal height" for the operator. doing. This configuration is effective when the height of the upper surface of the magnetic field source below the superconducting magnet is high, as in the case of the second aspect.

In the MRI apparatus of the present invention, the superconducting magnet further includes a magnetic shield plate disposed above and below the magnetic field generating source, and a yoke supporting the magnetic shield plate. By embedding part or all of the side magnetic shield plate under the floor, the height from the position where the operator can stand to the center of the imaging region is adjusted (claim 7). In this configuration, the superconducting magnet has a magnetic shield around the magnetic field generating source, and part or all of the lower magnetic shield plate of the magnetic shield is buried under the floor to lower the center position of the imaging region. This achieves the "ideal height" for the surgeon.

In the MRI apparatus according to the present invention, a part or all of the outer peripheral portion of the lower surface of the upper cover among the covers covering the magnetic field generating source is tapered (claim 8). In this configuration, by providing a tapered portion on a part or all of the outer peripheral portion of the lower surface of the upper magnetic field generating source of the superconducting magnet, the position of the head when the operator takes a forward tilt posture and the lower surface of the upper cover Can be increased substantially.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings. 1 and 2 show a first embodiment of the MRI apparatus according to the present invention. FIG. 1 shows M of the present embodiment.
FIG. 2 is a vertical cross-sectional view of the RI device (as viewed from the side), and FIG. 2 is a front perspective view showing its appearance. In FIG. 2, the MRI apparatus has a magnetic field source 2 above and below an imaging region 1, and the upper and lower magnetic field sources 2 are connected by a connecting pipe 3. Magnetic field source 2
Generates a uniform static magnetic field in the imaging region 1. The magnetic field source 2 includes a superconducting coil for generating a static magnetic field in the imaging region 1, a refrigerant for cooling the superconducting coil to a superconducting state, a cooling container for containing the superconducting coil and the refrigerant, and the like. The upper and lower cooling vessels are connected through a connecting pipe 3. The cooling container has a refrigerator for cooling the cooling container.

In FIG. 1, the upper and lower magnetic field generating sources 2 are supported by a magnetic shield plate 4 arranged outside thereof.
The magnetic shield plates 4 are arranged on the left and right of the photographing area 1.
It is supported by a book yoke 5. The magnetic shield plate 4 and the yoke 5 are made of a ferromagnetic material such as iron, and constitute a magnetic shield for a static magnetic field generated by the magnetic field source 2. As described above, in the present embodiment, the magnetic field source 2 and the magnetic shield constitute a superconducting magnet of the vertical magnetic field type. The yoke 5
In order to increase the openness of the photographing area 1, it is arranged behind the center of the photographing area 1 and at a position away from the photographing area 1. With this configuration, most of the magnetic flux lines of the static magnetic field formed in the imaging region 1 by the magnetic field source 2 are transferred to the upper magnetic field source 2, the upper magnetic shield plate 4, the left and right yokes 5, and the lower yoke 5. Since the light returns to the imaging region 1 via the magnetic shield plate 4 on the side and the magnetic field source 2 on the lower side, the leakage of the magnetic field to the outside of the apparatus is extremely reduced. Further, the openness of the MRI apparatus is improved by the vertical arrangement of the magnetic field generation source and the rear arrangement of the yoke 5.

In the MRI apparatus that obtains a uniform static magnetic field required for imaging by using the superconducting coils separated vertically as described above, as described below, a sufficiently large coil radius,
A sufficient facing distance required for photographing is required. M in which a magnetic field source 2 using a superconducting coil is arranged above and below an imaging region 1
An example of a magnet for an RI apparatus is disclosed in Japanese Patent Application Laid-Open No. 9-153408 (known example 3). In this type of magnet, as disclosed in Known Example 3, when the diameter of the superconducting coil is increased, the uniformity of the static magnetic field in the imaging region 1 tends to be improved. Improving the uniformity of the static magnetic field in the MRI apparatus is an essential condition for high-speed, high-accuracy imaging in recent years, and therefore a sufficiently large coil radius is required for the magnet for the MRI apparatus.

Further, as described in Known Example 3,
In a superconducting magnet in which two magnetic field sources 2 are arranged at an interval, if the interval is widened, each magnetic field source 2 requires more magnetomotive force, that is, each superconducting coil requires an expensive superconducting wire. Needs to be wound more, which increases the cost of the MRI apparatus. Therefore, the facing distance is required to be narrow within a necessary and sufficient range.

As described above, in the open type MRI apparatus using the superconducting magnet, the outer diameter of the cooling vessel containing the superconducting coil becomes large, but the space between the upper and lower magnetic field sources 2 is not so large, The dimensions are such that some allowance is provided for the interval at which the subject lying on the bed can be inserted. In this embodiment, the former dimension is 1,500 mm to 2,
The size is selected to be about 000 mm (radius is about 750 mm to 1,000 mm), and the size of the latter is selected to be about 400 mm to 600 mm. Regarding the height of the center position 8 of the photographing area 1,
The selection is made in consideration of the operability of the operator 6 during the operation. When the operator 6 performs an IVR operation or the like on the subject inserted into the imaging region 1 with the MRI apparatus having such a configuration, as described in the document 1, the operator 6 It is appropriate to work in a forward leaning posture (posture with the knee extended and middle waist) as shown in FIG. In the case of the forward leaning posture, fatigue during work is small, and long-time work is possible. In addition, as described below, it is possible to extend the hand forward in a forward leaning posture.

When the surgeon 6 takes a forward leaning posture as shown in FIG. 3, the photographing area 1 is the "ideal photographing area" 1A shown in the figure.
In this position, the operation is easy for the operator 6 and the hand can be extended to a far distance. Edited by Jiro Ohara, Collection of Human Body and Motion Dimensions for Designers, p. 22, (Shokokusha, 1
According to the document 2 issued on February 10, 985) (hereinafter referred to as reference 2), when the operator 6 takes a forward tilted posture, the height from the floor surface 7 to the head of most of the operator 6 is 1, 300mm ~ 1,50
It is in the range of 0mm, and reachable distance is 900mm ~ 1,
It is in the range of 050 mm. Considering the above data of Document 2 and the distance between the upper and lower magnetic field sources 2, the distance 9 between the center position 8 of the imaging region 1 and the floor 7 is set to 1,000 mm or more.
By selecting 1,300 mm, an "ideal shooting area" 1A is obtained. Hereinafter, this distance 9 is referred to as “ideal height”.

"Ideal photographing area" 1A in FIG.
Is applied to the imaging region 1 of the MRI apparatus in FIG. 1, and the height from the floor surface 7 on which the operator 6 stands to the center position 8 of the imaging region 1 is set to an ideal height 9 (1,000 mm). ~
1,300 mm), the operator 6 takes a forward leaning posture, so that the head of the operator 6 fits in the space between the upper and lower magnetic field sources 2 and the hand of the operator 6 6 reaches a range of 900 mm to 1,050 mm at the longest. Therefore, if the position where the operator 6 stands is about 100 mm from the outer periphery of the cooling container, the hand of the operator 6 reaches 800 mm to 950 mm from the outer periphery of the cooling container.
Can easily access the subject inserted into the imaging region 1, and can perform an IVR operation or the like on the subject without causing significant fatigue.

In this embodiment, the position of the "ideal imaging region" is achieved by setting the thickness of the lower magnetic field source 2 and the lower magnetic shield plate 4 to appropriate thicknesses. I have. Normally, the height of the cooling vessel of the magnetic field source 2 and the distance between the upper and lower magnetic field sources 2 are almost determined by the required specifications of the superconducting magnet, so in the present embodiment, the thickness of the lower magnetic shield plate 4 is mainly reduced. By adjusting, the height of the middle point of the cover that covers the center of the imaging region 1, that is, the side of the magnetic field source 2 arranged above and below, facing the imaging region 1, is set to 1,00
The size is between 0 mm and 1,300 mm.

In this embodiment, an MRI apparatus having a structure in which a superconducting magnet is provided with a magnetic shield has been exemplified. However, a superconducting magnet which does not require a magnetic shield may be used. By arranging a mechanically strong plate below the magnetic field source 2 on the side and adjusting the thickness thereof, the height of the center of the imaging region 1 can be optimized.

FIG. 4 shows a second embodiment of the MRI apparatus of the present invention. In this embodiment, the step 11 is provided at a position where the surgeon 6 stands. In this embodiment, the main part of the superconducting magnet is the same as that of the first embodiment, but the thickness of the lower magnetic field source 2 and the lower magnetic shield plate 3 is larger than that of the first embodiment, The distance from the surface 7 to the center height 8 of the photographing area 1 exceeds the ideal height 9 described above. For this reason, in this embodiment, the step 11 is arranged at the position where the operator 6 stands, and the distance between the position 10 where the operator 6 stands and the center position 8 of the imaging region 1 is set to the ideal height 9. Has been adjusted.
The step 11 is preferably fixed to the floor 7.
However, it is not limited to the illustrated box type,
There is no limitation as long as it is for raising the position 10 where the operator 6 stands. For example, a structure in which the surgeon 6 can protrude around the lower magnetic shield plate 4 may be used. In addition, when the floor of the radiographing room has irregularities and this is not preferable, the superconducting magnet may be used. Except for the position where the camera is placed, an object to be used as a step may be spread on the floor of the entire photographing room.

FIG. 5 shows a third embodiment of the MRI apparatus of the present invention. In this embodiment, the foot 12 is inserted under the superconducting magnet, and the entire superconducting magnet is lifted. In this embodiment, the main part of the superconducting magnet is the same as that of the first embodiment, but the thickness of the lower magnetic field source 2 and the lower magnetic shield plate 4 combined is greater than that of the first embodiment. It is getting thinner. For this reason, in this embodiment, the distance between the position 10 where the surgeon 6 stands and the center position 8 of the imaging region 1 is increased by putting the foot 12 under the magnet, and the ideal height 9 is obtained. Is adjusted as follows. The material of the foot 12 is not particularly limited, and may be any material having a strength capable of supporting the weight of the magnet. The number of the legs 12 is desirably three or more, but may be two as long as it has a sufficient supporting area.

In the second embodiment, the step 11
In the third embodiment, the insertion of the foot 12 has been described. However, it is possible to provide a means for changing the height of the step 11 or the foot 12. That is, the height of each can be controlled by providing a hydraulic control jack or the like to the stepping base 11 or the foot 12. The relative position of the operator 6 with respect to the center position 8 of the imaging region 1 of the MRI apparatus can be changed by using the stepping step and the height changing means of the foot. The height up to position 8 can be adjusted after installation of the device. In addition, when the height of the operator 6 is too high or too low, it is possible to adjust the height of the operator 6 to a level at which the operator 6 can easily work according to the height of the operator 6.

FIG. 6 shows a fourth embodiment of the MRI apparatus of the present invention. In this embodiment, a hole 13 is dug at a position where the operator 6 stands, and a position 10 where the operator 6 can stand is dug down from the floor surface 7. Also in the case of the present embodiment, as in the third embodiment, the combined thickness of the lower magnetic field source 2 and the lower magnetic shield plate 4 is smaller than that of the first embodiment. By digging the hole 13, the position 10 where the operator 6 stands is lower than the floor surface 7, and the distance between the position 10 where the operator 6 stands and the center position 8 of the imaging region 1 is increased. This hole 1
Digging 3 may be performed after the superconducting magnet is installed, or may be performed before the superconducting magnet is installed, and the hole 13 is positively used for loading and positioning when the superconducting magnet is installed. Is also good.

FIG. 7 shows a fifth embodiment of the MRI apparatus of the present invention. In this embodiment, the magnetic shield plate 4 below the superconducting magnet is embedded under the floor surface 7. In the present embodiment, first, the lower magnetic shield plate 4 is embedded below the floor surface 7, and then the remaining magnetic shield (the yoke 5 and the upper magnetic shield plate 4) and the upper and lower magnetic field sources 2 are arranged. Thus, assembly of the superconducting magnet is also facilitated. Here, the lower magnetic shield plate 4 may be entirely buried under the floor surface 7 or a part thereof may be buried under the floor surface 7. By embedding the lower magnetic shield plate 4 under the floor surface 7 in this manner, the distance from the floor surface 7 to the center position 8 of the photographing area 1 is adjusted to be the ideal height 9. .

FIG. 8 shows a sixth embodiment of the MRI apparatus of the present invention. In this embodiment, the magnetic field source 2 above the superconducting magnet
A tapered portion 15 is provided on the outer peripheral portion of the lower surface of the upper cover 14 that covers the upper surface. This taper processing is performed, for example, in a range of 200 mm to 400 mm from the outer periphery by 50 mm.
What is necessary is just to give a taper of 200 mm. Normally, the cover 14 is made of a thin non-magnetic material or the like, and a magnetic field generating source and a magnetic shield exist inside the cover 14. Therefore, it may be necessary to provide the magnetic field generating source 2 with a similar tapered portion. As in the present embodiment, when the tapered portion 15 is provided on the upper cover 14, the position of the head of the operator 6 and the tapered portion 14 are provided on the magnetic field generation source 2. When the height of the center position 8 of the imaging region 1 is too high and needs to be lowered, or when the operator 6 is tall, This is effective, for example, in eliminating the risk of the head coming into contact with the lower surface of the magnetic field source 2 when the head is in the forward tilted posture. The above-mentioned taper processing is not limited to the case of linear taper processing,
A slightly rounded curve or a combination of a plurality of straight lines may be used, or a tapered appearance may be used.

In the above description, the superconducting magnet has been treated as being composed of the magnetic field generating source 2, the magnetic shield plate 4, and the yoke 5, but there is no magnetic shield such as the magnetic shield plate 4 and the yoke 5. However, since the superconducting magnet can exert its function, it goes without saying that the present invention can be applied to an MRI apparatus including a superconducting magnet having only the upper and lower magnetic field sources 2. In this case, the combination of the lower magnetic field source 2 and the lower magnetic shield plate 4 may be replaced with only the lower magnetic field source 2. For example, as another example of the fifth embodiment, by embedding a part or the entirety of the lower magnetic field source 2 under the floor surface 7, a position 10 where the surgeon 6 stands and a central position 8 of the imaging region 1 are set. The height up to can be adjusted.

[0033]

As described above, according to the present invention, an operator can easily access a subject by using an MRI apparatus in which a magnetic field source using a superconductor is disposed vertically above and below an imaging region. It is possible to perform IVR or the like for a long time without feeling great fatigue.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a first embodiment of the MRI apparatus of the present invention.

FIG. 2 is a front perspective view showing the appearance of the first embodiment of the MRI apparatus of the present invention.

FIG. 3 is a diagram showing a relationship between a position where an operator stands and an ideal photographing position.

FIG. 4 is a longitudinal sectional view of a second embodiment of the MRI apparatus of the present invention.

FIG. 5 is a longitudinal sectional view of a third embodiment of the MRI apparatus of the present invention.

FIG. 6 is a longitudinal sectional view of a fourth embodiment of the MRI apparatus of the present invention.

FIG. 7 is a longitudinal sectional view of a fifth embodiment of the MRI apparatus of the present invention.

FIG. 8 is a longitudinal sectional view of a sixth embodiment of the MRI apparatus of the present invention.

FIG. 9 is a diagram in which an operator performs an IVR operation or the like from the side of the MRI apparatus.

FIG. 10 is a diagram in which an operator is performing an IVR operation or the like while sitting on a chair.

FIG. 11 is a diagram in which an operator performs an IVR operation or the like in an imaging region in a standing posture with a conventional MRI apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 imaging area 2 magnetic field source 3 connecting pipe 4 magnetic shield plate 5 yoke 6 surgeon 7 floor 8 center position 9 ideal height 10 position where surgeon stands 11 step 12 feet 13 hole 14 cover 15 tapered portion

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hiroshi Tazaki 1-1-1 Uchikanda, Chiyoda-ku, Tokyo Inside Hitachi Medical Corporation (72) Inventor Mitsuru Onuma 1-280, Higashi Koikebo, Kokubunji-shi, Tokyo Hitachi Design Laboratory (72) Inventor Isamu Takekoshi 1-280 Higashi Koigakubo, Kokubunji, Tokyo Hitachi Design Laboratory, Ltd.

Claims (8)

[Claims] 1. A magnetic resonance imaging apparatus (hereinafter, referred to as an MRI apparatus) having a superconducting magnet in which a magnetic field source using a superconductor is disposed vertically above and below an imaging region, from a position where an operator can stand. An MRI apparatus, wherein the height to the center of the imaging region is 1,000 mm to 1,300 mm. 2. The MRI apparatus according to claim 1, wherein a height from a position where the operator can stand to a center of the imaging region is adjusted by providing a step board on which the operator stands. 3. The MRI apparatus according to claim 1, wherein a foot for adjusting a height is provided below the superconducting magnet to adjust a height from a position where an operator can stand to a center of an imaging region. An MRI apparatus characterized in that: 4. The MRI apparatus according to claim 2, wherein the step or the foot is provided with a height changing means, and the height of the step or the foot can be changed by the height changing means. MRI apparatus. 5. The MRI apparatus according to claim 1, wherein a height from a position where the operator can stand to a center of the imaging region is adjusted by digging a floor surface at a position where the operator can stand. MRI equipment. 6. The MRI apparatus according to claim 1, wherein a part of or the whole of the superconducting magnet is buried under the floor to adjust a height from a position where an operator can stand to a center of an imaging region. An MRI apparatus characterized by the above-mentioned. 7. The MRI apparatus according to claim 6, wherein said superconducting magnet includes a magnetic shield plate disposed above and below said magnetic field generating source, and a yoke supporting said magnetic shield plate. An MRI apparatus wherein a height from a position where an operator can stand to a center of an imaging region is adjusted by embedding a part or the whole of a lower magnetic shield plate under the floor. 8. The MRI apparatus according to claim 1, wherein a part or all of the outer peripheral portion of a lower surface of an upper cover among the covers covering the magnetic field generating source is tapered. apparatus.