JP2794066B2 - Nuclear magnetic resonance imaging equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a nuclear magnetic resonance imaging apparatus (hereinafter, referred to as MRI).
It is called a device. In particular, the present invention relates to an MRI apparatus in which a couch can be moved in two axes in a body axis direction and a direction perpendicular thereto, and an imaging region of a subject can be moved to the center of a magnetic field.

[Conventional technology]

First, a static magnetic field generator of an MRI apparatus will be briefly described. As the static magnetic field generation method of the MRI apparatus, a superconducting or normal conducting electromagnet method or a permanent magnet method is currently used. In each of these cases, a uniform magnetic field space having a predetermined size is formed. The uniform magnetic field space is required to set the examination part of the subject by applying a gradient magnetic field. Conventionally, the uniform magnetic field space is a static magnetic field generating device, that is, a device formed in the center of the space in the magnet. Met.

Next, the high frequency irradiation coil and the bed in the MRI apparatus will be described. The conventional high-frequency irradiation coil uses a saddle-shaped coil 60 as shown in FIG. 12, and has a cylindrical shape. In general, the saddle coil 60 is fixed to a resin bobbin 61, and the diameter of the bobbin 61 becomes an opening of a magnetic field generator main body (hereinafter, referred to as a gantry) of the MRI apparatus. In addition, the diameter of the opening is small within a range in which the subject can enter the opening due to the magnetic field generation efficiency of the magnet, and the diameter is about 60 cm, and the subject can move in the radial direction within the gantry opening. There is only a small space depending on the physique of the subject. Therefore, the couchtop on which the subject lies lies on the couch, and moves vertically to move the subject to the optimal height to lay the subject on the couch, and moves vertically to move the subject to the center of the magnetic field (body axis direction). It suffices to have only a mechanism for (moving).

Here, a conventional general bed vertical and vertical movement mechanism will be described with reference to FIG. For the vertical movement of the top plate, a link (1) 62 and a link (2) 63 form a pantograph to guide the left / right and front / back swing, and a pin (1) 64 and a pin (2) 65 fixed to the lower bed. The upper bed is supported by a hydraulic cylinder 73 rotatably mounted on the upper bed.

In addition, the vertical movement of the top is guided vertically and horizontally by rails 66 fixed to the upper bed and rollers 74 fixed to the top 70, and is not shown so that the top is not bent by the load. There are provided several rollers, which enable vertical movement of the top plate. The chain 72 is fixed to a plate 71 fixed to the rear of the top plate 70, and the top plate 70 is driven by transmitting the driving force from the motor 68 and the reduction gear 69 to the sprocket 67.

[Problems to be solved by the invention]

According to the above-described conventional technology, it is impossible to position any imaging region at the center of the magnetic field and perform imaging at a position where the magnetic field uniformity is good. For example, when imaging the shoulder, the gantry opening has a diameter of only about 60 cm, and the top plate cannot move laterally, so the subject hardly moves, and after all, it is necessary to take an image in a place with poor magnetic field uniformity Image wrapping due to non-uniform magnetic field, S / N
And a good image could not be obtained. Also,
Even if the gantry opening is wide and the subject can move within the opening, the couch does not move in the direction perpendicular to the body axis (lateral movement), so that the subject must hold an unreasonable posture for a long time and perform imaging. In addition, the subject is not only forced to suffer, but also has many difficulties, such as the subject moving due to an unreasonable posture, which easily causes motion artifacts.

An object of the present invention is to provide an MRI that can easily move a subject within a gantry opening so that an imaging region can be easily aligned with the center of a magnetic field.
An object of the present invention is to provide a device, which can obtain a good image at any imaging site and reduce pain of a subject who undergoes MRI diagnosis.

[Means for solving the problem]

The above problem is that a gantry having a built-in static magnetic field and each magnetic field generating means of a gradient magnetic field, and having an opening for inserting a subject into an imaging position formed by the magnetic field generating means, and a gantry, A nuclear magnetic resonance imaging apparatus including a bed that lays down and moves the imaging region to the imaging center along the body axis direction of the subject, wherein the gantry opening is formed into a substantially rectangular shape that is long in the width direction in the opening front view. A mechanism for forming and moving the couchtop at least in two directions, the body axis direction of the subject and a horizontal direction intersecting the body axis direction, on the couch on which the subject rests, A mechanism that can be fixed at an arbitrary position within a movement stroke in a direction perpendicular to the moving direction is provided.

In addition, built-in static magnetic field, gradient magnetic field generation means,
A gantry having an opening for inserting a subject into a photographing position formed by the magnetic field generating means on the side, and laying down the subject and moving the photographed region to the photographing center along the body axis direction of the subject In a nuclear magnetic resonance imaging apparatus including a bed, the gantry opening is formed in a substantially rectangular shape that is long in the width direction when the opening is viewed from the front, and the bed on which the subject rests is provided with at least a top plate. A mechanism for moving the specimen in two directions, that is, the body axis direction and a horizontal direction intersecting the body axis direction, and the top plate clearly indicates the position at a position where the center of the magnetic field generating means coincides with the center in the direction perpendicular to the body axis. It is also solved by providing means.

Further, a gantry having a built-in static magnetic field and gradient magnetic field generating means, and having an opening on the side for inserting a subject into an imaging position formed by the magnetic field generating means, In a nuclear magnetic resonance imaging apparatus having a bed for moving a part to the imaging center along the body axis direction of the subject, a tabletop is moved in the body axis direction of the subject on the bed on which the subject is placed. A mechanism and a mechanism for moving in the horizontal direction intersecting the body axis direction within the static magnetic field can also be solved by providing at least the gantry opening into a substantially rectangular shape long in the width direction in the opening part front view. This problem can also be solved by forming and moving the body axis horizontal moving mechanism to an arbitrary position within the range of the width of the substantially rectangular opening.

Furthermore, a gantry having a built-in static magnetic field and a gradient magnetic field generating means, and having an opening on the side for inserting the subject into an imaging position formed by the magnetic field generating means, and laying down the subject. In a nuclear magnetic resonance imaging apparatus comprising: a bed for moving an imaging region to the center of imaging along the body axis direction of the subject, the couch on which the subject is placed is moved with a top plate in the body axis direction of the subject. This mechanism is also solved by moving the top plate in a horizontal direction intersecting the body axis direction in a static magnetic field, so that the gantry opening is moved to the front of the opening. Formed in a substantially rectangular shape that is long in the width direction when viewed, the moving mechanism in the body axis direction moves the top plate to an arbitrary position within the range of the body axis direction and the width of the substantially rectangular opening. It is also solved by.

[Action]

The movement of the couch top in the body axis direction of the subject serves to position the imaging part of the subject at the center of the magnetic field in the depth direction of the gantry, and also in a direction or an opening crossing the body axis direction in the horizontal direction. The movement of the couch top in the width direction of the part has an effect of positioning the imaging region of the subject at the center of the magnetic field in the gantry width direction.

In addition, forming the gantry opening in a substantially rectangular shape that is long in the width direction when viewed from the front of the opening secures a space for any imaging part of the subject to be positioned at the center of the magnetic field (that is, when the imaging of the shoulder is targeted). This means that a space about three times the width of the shoulder of the subject is required).

A mechanism that fixes the movement of the tabletop in a direction that intersects horizontally with the body axis of the subject ensures that the subject is positioned with respect to the center of the magnetic field of the subject, and that the center of the tabletop in the body axis direction of the subject and the magnetic field generation The means for specifying a position where the center of the magnetic field coincides with the means facilitates returning the top plate once moved to the original center position.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a diagram showing a high-frequency irradiation coil according to the present invention. A coil 2 having a rectangular cross-section wide from a circular cross-section to the saddle-shaped coil shown in FIG. 12 is wound along the outer shape of the resin bobbin 1 to form a high-frequency irradiation coil. The current flowing through the coil 2 flows as indicated by an arrow 3, and the high-frequency magnetic field is formed as indicated by an arrow 4. The inner side of the resin bobbin 1 is provided with a cosmetic coating to cover the gantry opening. As described in the section of operation, the opening width of the resin bobbin 1 (gantry opening) is about 1000 mm (three times the shoulder width)
And Since this coil is a deformation of the saddle-shaped coil shown in FIG. 12, the non-uniformity of the high-frequency magnetic field, the efficiency, and the like become problematic. Experiments have confirmed that there is no practical problem if L / D ≧ 1.

As described above, the space for moving the subject in the direction perpendicular to the body axis is secured.

FIG. 2 shows an external view of the gantry and the bed. Opening height
A gantry 5 having a horizontally long rectangular resin bobbin 1 having a length of 470 mm and an opening width of 1000 mm, and a bed 8 having a top plate 6 for laying down a subject and a head rest 7 for mounting a head are arranged at a certain interval. .

Next, FIG. 3 shows a three-dimensional view of the bed of the present invention.
A resin top plate 6 which is constrained in the body axis direction and up and down and is movable in the direction of arrow 12 is attached to a resin support plate 9 which can move in the direction of arrow 11 (body axis direction). A lever 10 for locking the movement in the direction of the arrow 12 at an arbitrary position within the movement stroke in the direction of the arrow 12 is attached. That is, since the top plate 6 can move only in the direction of arrow 12 and the support plate 9 to which it is attached can move in the direction of arrow 11, the top plate 6 can move in two directions of arrows 11 and 12. become. In the present invention, both the top plate 6 and the support plate 9 are made of FRP resin.

Next, the moving structure will be described with reference to FIGS. FIG. 4 is a three-dimensional view of a state where the top plate 6 of FIG. 3 is removed. FIG. 5 is a longitudinal sectional view showing a state where the top plate 6 is attached. First, in FIG. 4, a rigid base 21 is attached to the upper part of the bed 8 and the roller 13 is attached to the lower part of the bed 21 via the roller receiver 14 and the pin 22 so as to be rotatable in the direction of arrow 23. Support plate 9 is disposed. The support plate 9 is prevented from bending by the contact of the roller 13 with the base 21. When the support plate 9 moves to the arrow 11 in the body axis direction, the roller 13 is disengaged from the base 21.
As a result, a certain degree of deflection can be prevented. A roller base is provided on the support plate 9.
15 is attached, and the roller 16 points to the arrow via the pin 22
It is installed rotatable in 24 directions. This roller 16
5, as shown in FIG. 5, does not contact the support plate 9 but contacts the top plate 6 to prevent the top plate 6 from dropping downward, and at the same time, to the body axis of the top plate 6. The movement in the direction perpendicular to the direction is smooth. In addition, a roller base 17 is mounted on the support plate 9, and a roller 18 is rotatably mounted on the roller base 17 via a shaft 26. As shown in FIG. 5, the rail 25 fixed to the lower portion of the top plate 6 and the roller 18
The top plate 6 does not come off at the top due to contact. This also serves to prevent the top plate 6 from being turned over by the weight of the subject when it moves in the direction perpendicular to the body axis direction. As shown in FIG. 6, this mechanism portion may be structured so that the roller 28 is prevented from coming off in the upper direction, the movement is prevented in the body axis direction, and the roller 27 is guided from the right angle direction.

In FIG. 4, on the support plate 9, in addition to the above, a plate 19 and a rack 20 having a counterbore in the center in the bed width direction are mounted. Its use will be described with reference to FIG. The plate 19 is used in combination with a plunger 29 fixed to the top plate 6 to clearly indicate that the center in the width direction of the top plate 6 coincides with the center in the width direction of the bed. The plunger 29 has a structure as shown in FIG. The structure is such that the ball 31 is always pressed by the spring 30, so that even if the ball 31 is pushed in, it returns to the original state. Therefore, the ball 31 of the plunger 29 is retracted on the plate 19 described above, but the ball 31 protrudes when it comes to the position of the counterbore in the center of the plate 19, so that it is locked there, but a certain force or more. By pushing the top plate 6, the ball 31 comes out of the counterbore and can be moved. Therefore, the stroke center of the top plate 6 can be clearly indicated. Instead of using this method, the center may be clearly indicated by attaching the seal 80 shown in FIG. 3 to the bed 8 and the top plate 6.

Next, the role of the rack 20 will be described with reference to FIG. A pinion 32 fixed to the lever 10 is engaged with a rack 20 fixed on the support plate 9. The roller 34 fitted on the shaft 35 fixed to the top plate 6
It can enter and move only in the direction of arrow 37. The spring 36 pulls the lever 10 so that the rack and the pinion always mesh with each other. That is, the top plate 6 cannot be moved relative to the support plate 9 in a state where the top plate 6 and the support plate 9 are integrated. The meshing is released by pushing the lever 10 in the direction of the arrow 38, and the top plate 6 can be moved with respect to the support plate 9.

The above is the mechanism in which the top plate 6 moves in a direction perpendicular to the body axis. In the present invention, the movement is performed manually, but may be performed electrically. Further, the moving stroke is ± 100 mm or more.

Next, the body axis direction moving mechanism of the present invention will be described with reference to FIGS.
This will be described with reference to the drawings. FIG. 9 is a three-dimensional view showing only the upper part of the bed, with the support plate 9 removed. FIG. 10 is a cross sectional view thereof. In FIG. 10, a rail 44 having a square cross section fixed to the side of the base 21 of the bed 8 has a roller 46 for preventing vertical and vertical displacement and a roller 46 for moving in the axial direction, and a roller 45 for removing backlash in the horizontal direction. The plate fixing plate 39 is mounted so as to be movable only in the body axis direction. Further, a sprocket, a chain, a motor, and the like are mounted inside the base 21, so that the chain 47 and the support plate fixing plate 39 are clamped by the clamp plate. In FIG. 9, the operation of the chain 47 will be described. A sprocket 40 rotatably attached to the bed 8, a sprocket 41 for increasing a winding angle of a sprocket 42 described later, and a sprocket 42 for transmitting rotation attached to a shaft end of a motor 43 with a speed reducer, as shown in the drawing. Chain 47
Is wrapped around. Chain when motor 43 rotates
Since the 47 moves, the clamp plate 48 and the support plate fixing plate described above
39 is configured to move in the body axis direction.

The above is the description of the structure. The operation will be described below with reference to FIG. The subject 50 is placed on the top plate 6, and the high-frequency receiving coil 52 is set on the shoulder of the subject 50. The top plate 6 is moved by aligning the imaging part with the positioning light 51 built in the gantry, and the center of the coil 52 is adjusted, and the top plate 6 is moved by a predetermined amount such that this position matches the center of the magnetic field in the gantry. Perform the operation of sending images to the gantry for shooting. Then, since the obtained image is taken in a place with good uniformity, the S / N becomes good without being affected by the non-uniformity of the magnetic field.

〔The invention's effect〕

a. Since the top of the couch can be moved in the vertical and horizontal directions within the static magnetic field, the imaging region of the subject can be moved to the center of the magnetic field by moving the top. It is not necessary to have the subject move as in the above, and the subject does not have to be forced.

b.In order to move the subject in the direction perpendicular to the body axis, the opening of the gantry was widened in the width direction. It has the advantage of relaxing.

c. Since the imaging site can be moved to the center of the magnetic field, the S / N of the image is improved.

d. Since the imaging region can be moved to the center of the magnetic field, aliasing artifacts due to non-uniformity of the static magnetic field are eliminated.

e. Since the imaging region can be moved to the center of the magnetic field, the subject does not have to be forced, and motion artifacts can be reduced.

f. Positioning of the top plate in the lateral movement direction is ready.

g. Once the tabletop is moved laterally, it can be easily returned to its original center position.

h.Because the subject can be moved to any position within the static magnetic field, the subject can be moved to the center of the magnetic field without moving the subject or pulling out the tabletop, and the burden and operation on the subject The burden on the user can be reduced, and the photographing time can be reduced.

And so on.

[Brief description of the drawings]

In the accompanying drawings, FIG. 1 is a three-dimensional view of the high-frequency irradiation coil of the present invention, FIG. 2 is a three-dimensional view of the appearance of the MRI apparatus, FIG. 3 is a three-dimensional view of the external appearance of the bed of the present invention, and FIG. Fig. 5 is a three-dimensional view of the moving structure in the direction perpendicular to the body axis direction, Fig. 5 is a longitudinal sectional view of the moving structure in the direction perpendicular to the body axis direction of the bed of the present invention, and Fig. 6 is another embodiment of the bed of the present invention. Fig. 8 is a sectional view of a plunger, Fig. 8 is a three-dimensional view of a moving lock mechanism, Fig. 9 is a three-dimensional view of a moving structure of the bed of the present invention in the body axis direction, and Figs.
The figure is a cross-sectional view of the moving structure of the bed of the present invention in the body axis direction,
FIG. 12 is a view for explaining the operation of the present invention, FIG. 12 is a three-dimensional view showing the appearance of a conventional high-frequency irradiation coil, and FIG. 13 is a view showing a conventional bed moving mechanism. 1 ... bobbin, 2 ... coil, 3 ... current, 4 ... high frequency magnetic field, 5 ... gantry, 6 ... top plate, 7 ... head support,
8 ... bed, 9 ... support plate, 10 ... lever, 13, 16, 18
…… Roller, 19 …… Plate, 20 …… Rack, 29 …… Plunger, 32 …… Pinion, 25 …… Rail, 40, 41, 42 …… Sprocket, 43 …… Motor with reduction gear, 44 …… Rail .

Claims (6)

(57) [Claims] 1. A gantry having a built-in static magnetic field and a gradient magnetic field generating means, and having an opening on a side for inserting a subject into an imaging position formed by the magnetic field generating means; A nuclear magnetic resonance imaging apparatus including a bed that lays down and moves the imaging region to the imaging center along the body axis direction of the subject, wherein the gantry opening is formed into a substantially rectangular shape that is long in the width direction in the opening front view. A mechanism for forming and moving the couchtop at least in two directions, the body axis direction of the subject and a horizontal direction intersecting the body axis direction, on the couch on which the subject rests, A nuclear magnetic resonance imaging apparatus comprising: a mechanism that can be fixed at an arbitrary position within a movement stroke in a direction perpendicular to the direction of movement. 2. A gantry having a built-in magnetic field generating means for generating a static magnetic field and a gradient magnetic field, and having a side opening for inserting a subject into an imaging position formed by the magnetic field generating means; A nuclear magnetic resonance imaging apparatus including a bed that lays down and moves the imaging region to the imaging center along the body axis direction of the subject, wherein the gantry opening is formed into a substantially rectangular shape that is long in the width direction in the opening front view. A mechanism for forming and moving at least a top plate on a bed on which the subject rests in two directions: a body axis direction of the subject and a horizontal direction intersecting the body axis direction; A nuclear magnetic resonance imaging apparatus, comprising: means for specifying the center of the direction and the center of the magnetic field generating means at a position where the center coincides. 3. A gantry having a built-in static magnetic field and a gradient magnetic field generating means, and having an opening on a side for inserting a subject into an imaging position formed by the magnetic field generating means; In a nuclear magnetic resonance imaging apparatus including a bed that lays down and moves the imaging region to the imaging center along the body axis direction of the subject, a tabletop is placed on the bed on which the subject is placed in the body axis direction of the subject. A nuclear magnetic resonance imaging apparatus comprising at least a mechanism for moving and a mechanism for moving in a static magnetic field in a horizontal direction crossing the body axis direction. 4. The gantry opening is formed in a substantially rectangular shape that is long in the width direction when the opening is viewed from the front, and the mechanism for moving the body axis in the horizontal direction is provided within a range of the width of the substantially rectangular opening. The nuclear magnetic resonance imaging apparatus according to claim 3, wherein the apparatus is configured to be moved to a position. 5. A gantry having a built-in static magnetic field and a gradient magnetic field generating means, and having an opening at a side for inserting a subject into an imaging position formed by the magnetic field generating means; A bed for moving the imaging part to the imaging center along the body axis direction of the subject in a nuclear magnetic resonance imaging apparatus, wherein the couch on which the subject rests has a tabletop in the body axis direction of the subject. A nuclear magnetic resonance imaging apparatus, further comprising a mechanism for moving the tabletop in a body axis direction in a static magnetic field in a horizontal direction crossing the body axis direction. 6. The gantry opening is formed in a substantially rectangular shape that is long in the width direction when viewed from the front of the opening, and the moving mechanism in the body axis direction moves the top plate in the body axis direction and the opening in the substantially rectangular shape. 6. The nuclear magnetic resonance imaging apparatus according to claim 5, wherein the apparatus moves to an arbitrary position within a range of the width.