JP6296631B2 - Magnetic resonance imaging system - Google Patents

Description

  The present invention relates to a magnetic resonance imaging (hereinafter referred to as MRI; Magnetic Resonance Imaging) apparatus including a static magnetic field generator and a gradient magnetic field generator.

  The MRI apparatus obtains a magnetic resonance image (tomographic image) representing the physical properties of the subject placed in the imaging space using the nuclear magnetic resonance phenomenon of the nucleus. In general, an MRI apparatus generates a static magnetic field generation apparatus having a static magnetic field generation source that generates a uniform magnetic field (static magnetic field) in an imaging space, and a high-frequency electromagnetic wave for generating nuclear magnetic resonance in a nucleus of a living tissue of a subject. An irradiation coil to be generated, a receiving coil for detecting a nuclear magnetic resonance signal generated by nuclear magnetic resonance, and a gradient magnetic field that generates a linear gradient magnetic field superimposed on a uniform magnetic field to give positional information to the nuclear magnetic resonance signal A gradient magnetic field generator having a generation source is provided. At the time of imaging by the MRI apparatus, a gradient magnetic field generator superimposes a linear gradient magnetic field in the X, Y, and Z axis directions on a subject placed in a uniform magnetic field according to a desired pulse sequence, and the atomic spin of the subject is changed to Larmor. Excited magnetically at frequency. With this excitation, a magnetic resonance signal is detected, and a magnetic resonance image of the subject, for example, a two-dimensional tomographic image is reconstructed.

  The gradient magnetic field generator is desired to have a large inner diameter (bore) in order to maximize the space for the subject to enter and relieve the feeling of blockage. On the other hand, the smaller the inner diameter of the static magnetic field generator, the smaller the magnetic energy, so it is not preferable to increase the outer shape of the gradient magnetic field generator. That is, the gradient magnetic field generator is desired to be thin.

  Vibration may occur in the gradient magnetic field generator and the static magnetic field generator. This vibration may cause degradation of tomographic images and noise around the MRI apparatus. When the gradient magnetic field generator is thinned, the rigidity of the entire apparatus decreases and the vibration tends to increase. As a conventional technique related to a vibration suppression method for an MRI apparatus, a technique has been proposed in which a gradient magnetic field generation source is laminated with a viscoelastic sheet and a glass fiber mat, and the attenuation ratio is increased to reduce the noise of the gradient magnetic field generation apparatus ( Patent Document 1). In addition, a technique has been proposed in which a reinforcing rib is provided at a portion protruding in the axial direction of the gradient magnetic field generator to reduce vibration while reducing the thickness of the gradient magnetic field generator (see Patent Document 2).

JP-A-2-124139 JP 2013-39152 A

  However, with the technique disclosed in Patent Document 1, it is considered that the vibration at the resonance point can be reduced by increasing the damping ratio, but the vibration reducing effect at a frequency other than the resonance point is small. Further, in the technique of Patent Document 2, it is considered that the vibration of the protruding portion at the axial end of the gradient magnetic field generator can be reduced by the reinforcing rib, but the vibration other than the axial end cannot be reduced.

  Therefore, the problem to be solved by the present invention is to provide an MRI (magnetic resonance imaging) apparatus capable of reducing vibration without increasing the thickness of the gradient magnetic field generator.

In order to solve the above problems, the present invention has a cylindrical static magnetic field generation source capable of introducing a subject into an internal imaging space, and generates a uniform magnetic field in the imaging space by the static magnetic field generation source. And a gradient magnetic field generation device having a gradient magnetic field generation source for superimposing a gradient magnetic field on the imaging space, wherein the gradient magnetic field generation source is disposed outside the gradient magnetic field main coil and the gradient magnetic field main coil. Between the provided gradient magnetic field shield coil, the gradient magnetic field main coil, and the gradient magnetic field shield coil so as to overlap the imaging space in the central axis direction of the gradient magnetic field generation source, and in the central axis direction It is an MRI (Magnetic Resonance Imaging) apparatus provided with a rigid member having a length that includes at least the entire passing area of the imaging space .

  According to the present invention, it is possible to provide an MRI (magnetic resonance imaging) apparatus capable of reducing vibrations without increasing the thickness of the gradient magnetic field generator.

1 is a schematic perspective view of an MRI (magnetic resonance imaging) apparatus according to a first embodiment of the present invention. 1 is a schematic longitudinal sectional view of an MRI apparatus according to a first embodiment of the present invention. It is a schematic longitudinal cross-sectional view of the gradient magnetic field generator of the MRI apparatus which concerns on the 1st Embodiment of this invention. It is a schematic longitudinal cross-sectional view of the gradient magnetic field generator of the MRI apparatus which concerns on the 2nd Embodiment of this invention. It is a schematic longitudinal cross-sectional view of an axial direction edge part among the gradient magnetic field generators of the MRI apparatus which concerns on the 3rd Embodiment of this invention. It is a schematic front view of the gradient magnetic field generator of the MRI apparatus which concerns on the 4th Embodiment of this invention.

Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In each figure, common portions are denoted by the same reference numerals, and redundant description is omitted.
(First embodiment)
FIG. 1 shows a schematic perspective view of an MRI (magnetic resonance imaging) apparatus 1 according to the first embodiment of the present invention. The MRI apparatus 1 has a cylindrical static magnetic field generator 2 capable of introducing the subject 10 into the internal imaging space 8 and a nuclear magnetic resonance in an atomic nucleus constituting a living tissue of the introduced subject 10. An irradiation coil 4 for irradiating a high-frequency signal, a gradient magnetic field generator 3 for giving position information to each signal emitted from the subject 10, and a rigid member 5 provided in the gradient magnetic field generator 3 (see FIG. 5) ), A receiving coil 22 for receiving a signal emitted from the subject 10, a bed 6 on which the subject 10 is loaded, and the like.

  The static magnetic field generator 2 generates a uniform magnetic field 7 (see FIG. 2) in the imaging space 8 in order to orient the spins of atoms constituting the living tissue of the subject 10. In order to correct the magnetic field of the uniform magnetic field 7 and increase the uniformity thereof, a shim coil (not shown) is provided on the imaging space 8 side of the static magnetic field generator 2.

  The static magnetic field generator 2 is supported by a vacuum vessel support leg 2f. The static magnetic field generator 2 has a cylindrical shape with a z-axis parallel to the horizontal direction as a central axis. The gradient magnetic field generator 3 is provided on the imaging space 8 side of the static magnetic field generator 2.

  The gradient magnetic field generator 3 has a cylindrical or elliptical shape having the same central axis as the static magnetic field generator 2 (with the z axis as the central axis), and a plurality of main coils (gradient magnetic field generation sources). 3a (see FIG. 3) and a plurality of shield coils (gradient magnetic field generating sources) 3b (see FIG. 3). The main coil 3a and the shield coil 3b are fixed by a resin 3c (see FIG. 3) including a laminated structure such as beads or glass fiber cloth.

  The irradiation coil 4 is provided on the imaging space 8 side of the gradient magnetic field generator 3. The irradiation coil 4 has a cylindrical or elliptical shape having the same central axis as the static magnetic field generator 2 (with the z axis as the central axis). The irradiation coil 4 irradiates a high-frequency signal in order to cause nuclear magnetic resonance to occur in atomic nuclei constituting the biological tissue of the subject 10. A receiving coil 22 is attached to the bed 6 in order to receive a magnetic resonance signal by nuclear magnetic resonance.

  Although details will be described later, a rigid member 5 is provided between the main coil 3 a and the shield coil 3 b of the gradient magnetic field generator 3. The rigid member 5 is formed of a material having higher axial rigidity than members such as beads and glass fiber cloth included in the surrounding resin 3c.

  FIG. 2 shows a schematic longitudinal sectional view of the MRI apparatus 1 according to the first embodiment of the present invention. The static magnetic field generator 2 includes a plurality of main coils (static magnetic field generation sources) 2a that are superconducting coils, a plurality of shield coils (static magnetic field generation sources) 2b that are superconducting coils, a main coil 2a that is a superconducting coil, and a shield. A cooling container 2e that houses and cools the coil 2b together with a coolant, a radiation shield plate 2d that shields radiation heat radiated from the vacuum container 2c, and a cooling container 2e and a radiation shield plate 2d that contain the cooling container 2e. Are housed in a vacuum environment and insulated, a vacuum container support leg 2f (see FIG. 1) for supporting the vacuum container 2c on the installation floor, a cooling container 2e and a radiation shield plate 2d in the vacuum container 2c. And a load support (not shown) that supports the heat insulation.

  The main coil (static magnetic field generation source) 2a has a ring shape, and its central axis coincides with the z-axis. In the present embodiment, a plurality (four in the example of FIG. 2) of main coils 2a are arranged along the z-axis direction.

  The main coil 2 a generates a static magnetic field that is a uniform magnetic field 7 in the imaging space (space) 8. The main coil 2a generates a static magnetic field in addition to the imaging space 8, and particularly generates a leakage magnetic field at a position farther than the main coil 2a in the z-axis direction with the imaging region 9 as the center. The shield coil (static magnetic field generation source) 2b can reduce the magnitude of this leakage magnetic field.

  The shield coil 2b has a ring shape, and its central axis coincides with the z-axis. A plurality of shield coils 2b (two (a pair) in the example of FIG. 2) are arranged in the z-axis direction. The shield coil 2b is disposed in the vicinity of the pair of main coils 2a disposed at both ends of the plurality of main coils 2a arranged in the z-axis direction. The shield coil 2b is disposed farther from the pair of main coils 2a disposed at both ends in the z-axis direction when the imaging region 9 is the center.

  FIG. 3 shows the gradient magnetic field generator 3 in FIG.

  Although the gradient magnetic field generator 3 is omitted in FIG. 2 and described as one, it actually has a plurality of main coils (gradient magnetic field generation sources) 3a. In addition, although one gradient magnetic field generation device 3 is omitted in FIG. 2 and is actually described, it actually includes a plurality of shield coils (gradient magnetic field generation sources) 3b. And the gradient magnetic field generator 3 has the resin 3c which fixes the main coil 3a and the shield coil 3b mutually.

The cross section of the main coil (gradient magnetic field generation source) 3a is arranged in an annular region having a cylindrical or elliptical shape with the z-axis as the central axis. The main coil 3 a generates a gradient magnetic field 20 that is superimposed on the uniform magnetic field 7 in the imaging space 8. The main coil 3 a generates a leakage magnetic field other than the imaging space 8. The shield coil (gradient magnetic field generation source) 3b can reduce the magnitude of this leakage magnetic field. The shield coil 3b is disposed in a cylindrical or elliptical region with the z axis as the central axis. The shield coil 3b is disposed farther than the main coil 3a with respect to the z axis. As described above, since the main coil 3a and the shield coil 3b are arranged in a circular or elliptical area centered on the z axis, the gradient magnetic field generator 3 also reflects this arrangement, and the z axis It has a cylindrical structure with a circular or elliptical cross section.
The shield coil 3b is disposed on the static magnetic field generator 2 side with respect to the main coil 3a. The gradient magnetic field generator 3 is attached to the vacuum vessel 2 c via the attachment member 21.

  The rigid member 5 is disposed between the main coil 3a and the shield coil 3b of the gradient magnetic field generator 3, and supports the main coil 3a and the shield coil 3b. Further, the rigid member 5 is continuously disposed at least on both sides of the imaging space 8 in the z-axis direction in the z-axis direction (the magnetic field direction of the uniform magnetic field 7), and imaging is performed in the direction in which the subject 10 is introduced. The space 8 has end portions outside the both ends. In other words, the rigid member 5 is a single member that is disposed so as to overlap with the imaging space 8 in the z-axis direction and has a length that includes at least the entire area of the imaging space 8 in the z-axis direction.

  The rigid member 5 is disposed between the main coil 3a and the shield coil 3b, and the resin 3c fixes the main coil 3a, the shield coil 3b, and the rigid member 5, and a gradient magnetic field generator as one structure. 3 is formed.

  Moreover, the rigid member 5 may be arrange | positioned continuously about the circumferential direction of the gradient magnetic field generator 3, or may be arrange | positioned discretely. The rigid member 5 is mechanically coupled to the gradient magnetic field generator 3. Since the rigid member 5 is arranged in a region having a large magnetic field between the main coil 3a and the shield coil 3b of the gradient magnetic field generator 3, an eddy current is generated in the rigid member 5 when the gradient magnetic field generator 3 is energized. It is desirable that the electrical resistivity per cross section perpendicular to the z-axis direction of the rigid member 5 is equal to or higher than that of the outer wall of the gradient magnetic field generator 3.

  Next, suppression of vibration in the MRI apparatus 1 will be described.

  At the time of imaging, a uniform magnetic field 7 is generated in the imaging space 8 by the static magnetic field generator 2, but at the same time, a static magnetic field is also generated in a region where the gradient magnetic field generator 3 is disposed. In this manner, under the influence of the static magnetic field, a pulsed current flows through the main coil 3a and the shield coil 3b of the gradient magnetic field generator 3. Then, a static magnetic field generated in a region where the gradient magnetic field generating device 3 is arranged, and a pulsed Lorentz force acts on the main coil 3a and the shield coil 3b due to the coupling of the pulsed current, and the gradient magnetic field generating device. 3 vibrates.

  And the vibration of this gradient magnetic field generator 3 propagates to the vacuum vessel 2c via the attachment member 21 which attaches the gradient magnetic field generator 3 to the static magnetic field generator 2, and from the vacuum vessel 2c via the load support. By propagating to the radiation shield plate 2d and the cooling container 2e, each member of the static magnetic field generator 2 vibrates. In addition, although the example which attached the gradient magnetic field generator 3 to the static magnetic field generator 2 was given here, it is not restricted to this, For example, the gradient magnetic field generator 3 is attached to other members which comprise MRI apparatus 1, such as the vacuum vessel 2c. When the is attached, vibrations are similarly generated and transmitted through the connected points.

  The rigid member 5 is provided as a single structure between the main coil 3a and the shield coil 3b of the gradient magnetic field generator 3 and at least on both sides in the z-axis direction with respect to the imaging space 8 in which the uniform magnetic field 7 is generated. Yes. Thereby, the bending rigidity of the gradient magnetic field generator 3 in the z-axis direction (longitudinal direction) is increased by the bending rigidity of the rigid member 5 itself, and the bending deformation of the gradient magnetic field generator 3 due to vibration is reduced.

  Also, the main coil 3a and the shield coil 3b are fixed, and the two cylindrical or elliptical structures that have been softly fixed by the resin 3c are rigidly fixed, so that the bending rigidity proportional to the fourth power of the diameter is obtained. The bending deformation of the gradient magnetic field generator 3 due to vibration decreases and decreases.

  As a result, even when a Lorentz force is generated in a pulsed manner in the gradient magnetic field generator 3 at the time of imaging, the bending rigidity in the z-axis direction of the gradient magnetic field generator 3 is improved by the rigid member 5. The vibration amplitude of the gradient magnetic field generator 3 is suppressed, and the radiated sound (noise) propagating in the air is reduced.

Further, generally, currents flow in opposite directions in the main coil 3a and the shield coil 3b, so that the Lorentz force generated in each direction is also reversed. By rigidly fixing between the main coil 3a and the shield coil 3b, distortion in the cross section perpendicular to the z-axis direction is reduced, and the reliability of the gradient magnetic field generator is improved.
The bending rigidity in the longitudinal direction of the rigid member 5 is proportional to the cube of the radial dimension that is the plate thickness, and is proportional to the first power of the circumferential dimension that is the width direction. Therefore, if the rigid member 5 has a sufficient thickness to support the main coil 3a and the shield coil 3b in the radial direction, the circumferential dimension is short, that is, even in a discrete arrangement in the circumferential direction. The longitudinal bending rigidity can be improved.

  By adopting such an arrangement of the rigid members 5, it is possible to arrange the shim tray 12 (see FIG. 6) between the rigid members 5 that are discretely arranged in the circumferential direction. The shim tray 12 is a tray for installing a shim member used to ensure the accuracy of the uniform magnetic field 7. By securing a space in which the shim tray 12 is disposed between the main coil 3a and the shield coil 3b, the space can be used efficiently and an increase in the size of the MRI apparatus can be suppressed.

  Further, in the case of the MRI apparatus 1 that fixes the gradient magnetic field generation device 3 described above to the static magnetic field generation device 2, the vibration of the gradient magnetic field generation device 3 is reduced, so that the vibration to the static magnetic field generation device 2 is reduced. Propagation is also reduced, vibration of the static magnetic field generator 2 is also suppressed, and image deterioration due to an error magnetic field due to this can be suppressed.

  Further, since the gradient magnetic field generator 3 vibrates the gradient magnetic field 20, the tomographic image may be deteriorated due to the influence of the error magnetic field when the tomographic image is captured. By reducing, the influence of the error magnetic field can be reduced, and image degradation can be suppressed.

In this way, by installing the rigid member 5 using the space between the main coil 3a and the shield coil 3b of the gradient magnetic field generator 3, the vibration suppression effect can be achieved without increasing the thickness of the gradient magnetic field generator 3. Can be obtained.
In addition, when the rigid members 5 are discretely arranged in the circumferential direction, a shim tray 12 that stores a magnetic body for adjusting a static magnetic field is arranged between the rigid members 5 so that the space can be efficiently used and An MRI apparatus having a large bore can be provided.

(Second Embodiment)
FIG. 4 is a schematic longitudinal sectional view of the gradient magnetic field generator 3 of the MRI apparatus 1 according to the second embodiment of the present invention. The MRI apparatus 1 of the second embodiment is different from the MRI apparatus 1 of the first embodiment in that the rigid member 5 protrudes in the z-axis direction from the main coil 3a of the gradient magnetic field generator 3. Is a point. According to such a rigid member 5, in addition to the gradient magnetic field generating device 3 becoming more rigid, it is possible to reduce the vibration of the protruding portion of the shield coil 3b having a large vibration.

When a Lorentz force acts on the main coil 3a and the shield coil 3b, the protruding portion of the shield coil 3b at the end in the z-axis direction of the gradient magnetic field generator 3 is thin, so that vibration tends to increase. By lengthening the rigid member 5 in the axial direction to the protruding portion of the shield coil 3b, the vibration of the protruding portion of the shield coil 3b is reduced, the fatigue accumulated at the end of the shield coil 3b is suppressed, and damage is less likely to occur. be able to.
Further, when the gradient magnetic field generator 3 is operated, Joule heat is generated in the main coil 3a and the shield coil 3b, and the temperature of the gradient magnetic field generator 3 rises. However, the rigid member 5 protrudes to the end in the axial direction. The surface area of the gradient magnetic field generator 3 increases, and the efficiency of heat dissipation can be increased. as a result. When the gradient magnetic field generation device 3 is fixed to the static magnetic field generation device 2, the heat of the gradient magnetic field generation device 3 is propagated to the static magnetic field generation device 2 through the attachment member 21, and from the vacuum vessel 2c (see FIG. 2). By dissipating heat to the surroundings, consumption of the refrigerant stored in the cooling container 2e of the static magnetic field generator 2 can be suppressed.

(Third embodiment)
FIG. 5 shows a schematic longitudinal sectional view of a part of the gradient magnetic field generator 3 of the MRI apparatus 1 according to the third embodiment of the present invention. The MRI apparatus 1 according to the third embodiment is different from the MRI apparatus 1 according to the first embodiment between the rigid member 5 and the main coil 3a and shield coil 3b of the gradient magnetic field generator 3. It is the point provided with this rigid member 5a.

  According to another rigid member 5a, even if there is a gap between the rigid member 5, the main coil 3a, and the shield coil 3b, the main coil 3a and the shield coil 3b can be rigidly fixed. The rigid members 5 and 5a may protrude in the axial direction from the main coil 3a of the gradient magnetic field generator 3 as in the second embodiment.

(Fourth embodiment)
In FIG. 6, the schematic front view of the z-axis direction of the gradient magnetic field generator 3 of the MRI apparatus 1 which concerns on the 4th Embodiment of this invention is shown. The MRI apparatus 1 of the fourth embodiment is different from the MRI apparatus 1 of the first embodiment in that the rigid member 5 stores a shim tray 12 that stores a magnetic material for adjusting a static magnetic field. It is a point that doubles as a frame.

  Since the rigid member 5 rigidly fixes the main coil 3a and the shield coil 3b of the gradient magnetic field generator 3, the frame that houses the shim tray 12 also has a shape that expands in the radial direction. Thereby, the thickness of the shim tray 12 can be increased, the amount of the magnetic material stored for adjusting the static magnetic field can be increased, and the magnetic field uniformity can be improved.

  Further, an additional rigid member (not shown) can be inserted between the rigid member 5 that becomes the frame of the shim tray 12 and the shim tray 12. It is necessary to provide a gap between the rigid member 5 and the shim tray 12 for the convenience of inserting and removing the shim tray 12. However, by filling the gap with an additional rigid member (not shown), the rigidity of the shim tray 12 is also increased by the main coil 3a. And can be used to fix the shield coil 3b rigidly. In addition, the shim tray 12 can be made of a material having rigidity equivalent to that of the rigid member 5, so that the above effect can be enhanced.

(Fifth embodiment)
The MRI apparatus 1 of the fifth embodiment is different from the MRI apparatus 1 of the first to fourth embodiments in that the material of the rigid member 5 is carbon fiber reinforced plastics. Although carbon is a conductor, the cross-sectional area is reduced by becoming a fiber, the electric resistance per rigid member 5 is increased, and the eddy current is suppressed, thereby reducing heat generation.

  Moreover, since the rigidity is large while being lightweight, the natural frequency of the gradient magnetic field generator 3 is increased. In general, the vibration mode has a higher energy when the natural frequency is smaller. Therefore, when the natural frequency is higher, the energy of noise is reduced, leading to a reduction in overall. Therefore, it is effective for noise reduction.

  Furthermore, if the continuous fiber oriented in the axial direction of the gradient magnetic field generator 3 is used, the thermal conductivity in the axial direction is increased, and the heat generated in the central portion in the axial direction of the gradient magnetic field generator 3 can be quickly transferred to the axial end. Can be transported to. This works more effectively in the case of the second embodiment.

(Sixth embodiment)
The MRI apparatus 1 of the sixth embodiment is different from the MRI apparatuses 1 of the first to fourth embodiments in that the material of the rigid member 5 is metal fiber reinforced plastics. Examples of the metal include nonmagnetic materials such as aluminum and stainless steel.

  Although the metal is a conductor, the cross-sectional area is reduced by becoming a fiber, the electric resistance per rigid member 5 is increased, and the eddy current is suppressed, so that heat generation is reduced. Moreover, if the continuous fiber oriented in the axial direction of the gradient magnetic field generating device 3 is used, the thermal conductivity in the axial direction is increased, and the heat generated in the central portion in the axial direction of the gradient magnetic field generating device 3 can be quickly transferred to the axial end. Can be transported to. This works more effectively in the case of the second embodiment.

(Seventh embodiment)
The MRI apparatus 1 of the seventh embodiment is different from the MRI apparatus 1 of the first to fourth embodiments in that the material of the rigid member 5 is plastics reinforced with non-magnetic insulating fibers. Is a point. Examples of nonmagnetic insulators include boron.

  Since it is an insulator, since no eddy current is generated, the rigid member 5 does not generate heat. Moreover, since it is lightweight, the natural frequency of the gradient magnetic field generator 3 is increased, and this effectively acts in noise reduction.

(Eighth embodiment)
The MRI apparatus 1 of the eighth embodiment is different from the MRI apparatuses 1 of the first to fourth embodiments in that the material of the rigid member 5 is ceramic. Since the electric resistance is large, eddy current is hardly generated and the heat generation of the rigid member 5 is small.

  In the first to eighth embodiments described above, the superconducting coil is taken up as the static magnetic field generating sources 2a and 2b. However, the present invention is not limited to this. A normal conducting coil or a permanent magnet may be used as the static magnetic field generating sources 2a and 2b.

DESCRIPTION OF SYMBOLS 1 Magnetic resonance imaging apparatus 2 Static magnetic field generator 2a Static magnetic field generator (main coil)
2b Static magnetic field generation source (shield coil)
2c Vacuum container (outer wall of static magnetic field generator)
2d Radiation shield plate 2e Cooling vessel 2f Vacuum vessel support leg 3 Gradient magnetic field generator 3a Gradient magnetic field source (main coil)
3b Gradient magnetic field source (shield coil)
3c resin 4 irradiation coil 5, 5a rigid member 6 bed 7 uniform magnetic field 8 imaging space 10 subject 11 elastic body 12 shim tray 20 gradient magnetic field 22 receiving coil

Claims (10)

A static magnetic field generating device for generating a uniform magnetic field in the imaging space by the object have a static magnetic field generating source can be introduced cylindrical inside of the imaging space, the static magnetic field generating source,
A gradient magnetic field generator having a gradient magnetic field generation source for superimposing a gradient magnetic field on the imaging space,
The gradient magnetic field source is
A gradient main coil,
A gradient magnetic field shield coil provided outside the gradient magnetic field main coil;
The gradient magnetic field main coil and the gradient magnetic field shield coil are disposed so as to overlap the imaging space in the central axis direction of the gradient magnetic field generation source , and at least the entire area of the imaging space is passed in the central axis direction. A rigid member having a length to include ,
A magnetic resonance imaging apparatus comprising:   The magnetic resonance imaging apparatus according to claim 1, wherein the rigid member is a columnar member including both ends of the imaging space with respect to a central axis direction of the static magnetic field generation apparatus.   The magnetic resonance imaging apparatus according to claim 2, wherein both ends of the rigid member include both ends of the gradient magnetic field main coil with respect to a central axis direction of the static magnetic field generation apparatus.   The rigid member, and another rigid member having a different dimension in the central axis direction of the static magnetic field generator is provided between the main coil and the shield coil of the gradient magnetic field generator. Item 3. The magnetic resonance imaging apparatus according to Item 2.   The magnetic resonance imaging apparatus according to claim 2, wherein the rigid member also serves as a magnetic substance storage container provided in the gradient magnetic field generator or a frame into which the storage container is inserted.   The magnetic resonance imaging apparatus according to claim 1, wherein the rigid member is discretely arranged in a circumferential direction between the gradient magnetic field main coil and the gradient magnetic field shield coil.   The magnetic resonance imaging apparatus according to claim 1, wherein the rigid member is a carbon fiber reinforced plastic.   The magnetic resonance imaging apparatus according to claim 1, wherein the rigid member is a metal fiber reinforced plastic.   The magnetic resonance imaging apparatus according to claim 1, wherein the rigid member is a non-magnetic insulating fiber reinforced plastic.   The magnetic resonance imaging apparatus according to claim 1, wherein the rigid member is made of ceramics.

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