JPH10295665A - Magnetic resonance imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic resonance imaging device which has a high uniformity in the static magnetic field, allows the operator to perform the therapeutic process in usual attitude, and includes an open structure to a degree enough to smoothly make the care of a subject. SOLUTION: A magnetic resonance imaging device has a magnet frame 1 whose contour assumes spherical, and in the front part when viewed from the direction of Arrow A, a gap 3 is formed having a widh of such a size as admitting insertion of a bed 2 into the internal space 5. The internal space 5 is shaped spherical, can accommodate the bed 2 including top plate 6 completely, and in this condition, has a width to such a degree as admitting rotation of the bed 2 in the horizontal direction. The bed 2 is equipped with a rotational driving mechanism to rotate the top plate 6 in the horizontal direction at least 90 deg. in the condition that the subject P is placed thereupon.

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 (open type M) having an open type magnet mount.
RI).

[0002]

2. Description of the Related Art Various types of conventional open MRI systems have already been realized. As an example, (1) US Pat. No. 4,829,252 describes:
MRI system with open magnetic field (MRI SYSTEM WITH OPE) with open access to patient imaging area
N ACCESS TO PATIENT IMAGE VOLUME) is disclosed.

Further, (2) US Pat. No. 5,291,16
No. 9 describes a superconducting magnet assembly (OPEN ARCHITIT) for magnetic resonance imaging with an open structure.
ECTURE MAGNETIC RESONANCE IMAGING SUPERCONDUCTING
MAGNET ASSEMBLY). This is an example of a static magnetic field magnet having a double donut structure used in a lateral magnetic field type open MRI system, and a horizontal magnetic field type open MRI system has already been realized as a research system.

[0004] The open type MRI system of the above (1) has the following problems. That is, this MR
There is a problem that the open access (openness) provided by the I-system is not sufficient when taking into account the actual operation at the medical site.

On the other hand, the open type MRI system provided with the static magnetic field magnet having the double donut structure as described in (2) has the following problems. That is, the MRI system for diagnosis requires a high uniformity of the static magnetic field, but the MRI system of (2) has a problem that a sufficiently high uniformity of the static magnetic field cannot be obtained due to its structure.

[0006]

Accordingly, the present invention provides
Provide a magnetic resonance imaging apparatus with high uniformity of a static magnetic field, sufficient openness for an operator to perform a treatment procedure in a normal position, and for smooth care of a subject. The purpose is to do.

[0007]

In order to solve the above problems and achieve the object, a magnetic resonance imaging apparatus according to the present invention is configured as follows. That is, the magnetic resonance imaging apparatus of the present invention has a substantially spherical inner space capable of accommodating a bed on which a subject is placed, and is arranged in a substantially spherical shape along the inner space to generate a static magnetic field. A gap for inserting the bed into the inner space is formed in a magnet mount having a static magnetic field generating means.

[0008] Therefore, a diagnostician or a doctor can enter the internal space through the gap formed in the magnet mount,
Further, the subject can approach the bed on which the subject is placed.

Further, since the static magnetic field generating means is provided along the spherical inner space formed on the magnet mount, for example, a plurality of coil bundles or inner spaces discretely arranged along the inner space. When the static magnetic field generating means is constituted by a coil bundle continuously arranged along the axis, the coil pattern can be formed into a spherical shape.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view (bird's eye view) showing the appearance of an open type MRI apparatus according to an embodiment of the present invention.
It is. In the figure, arrow A indicates the direction in which the device is viewed from the front, arrow B indicates the direction in which the device is viewed from the side, and arrow C indicates the direction in which the device is viewed from the top.

Reference numeral 1 denotes a magnet base (base body) in which a static magnetic field magnet, a gradient magnetic field coil, a whole-body excitation (R)
F) A coil and a cooling mechanism for cooling these coils and the like are provided. Open type MR of this embodiment
The I device employs a so-called transverse magnetic field system, and the static magnetic field magnet generates a horizontal static magnetic field. 2 is floor 16
The bed is a bed that can move freely, and a top plate 6 on which the subject P is placed is attached to the top.

As shown in FIG. 1, the outer shape of the magnet mount 1 has a spherical shape, and the front portion viewed from the direction of arrow A is such that the bed 2 can be inserted into the inner space 5. Is formed. The inner space 5 is a spherical space, which can completely accommodate the bed 2 including the top plate 6 and has such a size that the bed 2 can be rotated in the horizontal direction in this state. The couch 2 is provided with a rotation drive mechanism (not shown in FIG. 1) for rotating the top 6 at least 90 degrees in the horizontal direction while the subject P is placed thereon.

Further, a passage window 7 is formed in the side of the magnet base 1 when viewed from the direction of arrow B, which leads from the inner space 5 to the outside of the magnet base 1. Note that a similar passing window is provided on a side surface portion facing the inside space 5. The passage window 7 allows a part of the top plate 6 (and a part of the body of the subject P placed thereon) to pass through when the bed 2 is stored in the inner space 5. .

The operation of the present apparatus during operation will be described with reference to FIGS. Figure 2 shows the magnet base 1
FIG. 4 is a view showing the outer surface of FIG. 4 and showing a state immediately before the bed 2 is inserted into the inner space 5. FIG. 2A is a view of the magnet base 1 as viewed from the front (the direction of arrow A in FIG. 1).
FIG. 2B is a view of the magnet base 1 viewed from the side (the direction of arrow B in FIG. 1), and FIG.
FIG. 6 is a diagram viewed from the direction of arrow C in FIG. 1A to 1C, the hatching indicates the outer surface of the magnet mount 1, and the broken line indicates the inside of the magnet mount 1. In this state, the bed 2 is moved in the direction of arrow I and inserted into the inner space 5 via the gap 3 as shown in FIG.

FIG. 3 is a cross-sectional view of the magnet base 1 at the center of the sphere, showing a state where the bed 2 is inserted into the inner space 5. As shown in these figures, the bed 2 inserted from the gap 3 is completely accommodated in the inner space 5 of the magnet gantry 1.
In this state, the table 6 is rotated by the rotary drive mechanism of the bed 2.
Is rotated in the direction of arrow T (or may be rotated in the direction opposite to arrow T) as shown in FIG.

FIG. 4 is a cross-sectional view of the magnet base 1 at the center of the sphere, showing a state where the top plate 6 is rotated by 90 degrees. By rotating the top board 6 by 90 degrees in the direction of the arrow T in this way, the body axis direction of the subject P is adjusted to the static magnetic field direction of the magnet mount 1 (Z-axis direction). Although not shown, it goes without saying that the direction of the magnetic field generated by the gradient coil is the Z-axis direction.

At this time, the toes (or heads) of the subject P placed on the table 6 are directed toward the passage window 7, where the diagnosis (assuming that the treatment is also used). The top plate 6 is shifted in the Z-axis direction in order to move the target portion for performing the operation (1) near the center of the static magnetic field / gradient magnetic field. FIG. 5 is a cross-sectional view of the magnet base 1 at the center of the sphere, and shows a state in which the top 6 is shifted with respect to the bed 2.

Depending on the position of the target part, it is necessary to increase the shift amount of the top 6. In such a case, the end of the top plate 6 on the head side or leg side of the subject P abuts on the inner wall of the magnet mount 1. However, in the present embodiment, as shown in the figure, a part of the top plate 6 (and the patient's body) protrudes outside the magnet gantry 1 through the passing window 7. As a result, the settable range of the target part is changed to the inner space 5.
Without being restricted by the size of the patient or forcing the patient into an unreasonable position. In addition, since the inner space 5 has a spherical shape, the subject P does not feel a feeling of pressure.

At this stage, an RF coil (not shown) for transmission / reception or reception only is set. R
There are various types of F coils, such as a volume coil and a surface coil, depending on the target region.

When, for example, cardiac imaging is performed by the MRI apparatus of the present embodiment, a diagnostic technician or a diagnosing physician attaches an RF coil to the subject P or performs Gd-D
Preparation and administration of a contrast agent such as TPA are performed. Here, in the MRI apparatus of the present embodiment, since the above-described gap 3 is formed in the magnet mount 1 and the top plate 6 is rotated by 90 degrees, as shown in FIG. 3
Allows the diagnostician or the diagnostician 14 to enter the inner space 5 of the magnet mount 1 and to approach the side of the table 6 on which the subject P is placed. Therefore, the above operation can be performed smoothly. Further, in a case where a so-called interventional method in which image diagnosis is simultaneously used in the treatment, that is, a so-called interventional method, is performed, the treating physician can perform the treatment in the standing or sitting position near the subject P.

Next, a specific configuration of the magnet base 1 will be described. 6A is a cross-sectional view of the center of the sphere when the magnet base 1 is viewed from the front (in the direction of arrow A in FIG. 1), and FIG. 6B is a case where the magnet base 1 is viewed from the top (FIG. 1). (In the direction of arrow C). In these drawings, only the coil portion corresponding to the static magnetic field magnet is shown as the internal structure of the magnet mount 1, and other coil portions, for example, gradient magnetic field coils and the like are omitted.

As shown in these figures, a spherical inner space 5 is formed in the magnet base 1 and a static magnetic field magnet 10 is provided along the inner space 5. The static magnetic field magnet 10 is composed of a coil bundle of a superconductor or a normal (electric) conductor for flowing an annular current. The static magnetic field magnets 10 may be discretely arranged in units of a coil bundle as described above, or may be arranged continuously like a solenoid coil.

A hatched portion 11 in FIGS. 6A and 6B shows a coil cooling mechanism. The magnet mount 1 is structurally divided by left and right hemispheres 1a and 1b since a gap 3 is formed in a part thereof.
b and connecting structure parts 12 and 13.
A current path, a cooling system, or the like is connected through the connection structures 12 and 13. The width 15 of the connecting portion 12 is desirably as short as possible so that the doctor 14 or the like can prepare for diagnosis or treatment beside the subject P without any trouble. On the other hand, since the connecting portion 13 is a portion corresponding to the insertion path of the bed 2, it is desirable that its width be as long as possible.

In order to allow the bed 2 to be smoothly inserted into the inner space 5 of the magnet base 1, the upper surface of the connecting portion 13 is flush with the floor 16 as shown in FIG. As described above, the bottom is buried in the floor 16 when the magnet mount 1 is installed.

FIGS. 7 and 8 are cross-sectional views showing the structure of the magnet mount 1 when the leakage magnetic field is reduced by the active shield type coil in the present embodiment. Here, the magnet base 1
In order to reduce the leakage magnetic field to the outside, an active shield type coil is wound around the outside of the static magnetic field magnet (coil bundle) 10.

FIG. 7 shows a case where the active shield type coil 17 is arranged in a spherical shape along the static magnetic field magnet 10. FIG. 8 shows a case in which the active shield type coil 18 is arranged away from the static magnetic field magnet 10, and in this case, the number of turns of the active shield type coil 18 can be made smaller than that in FIG. When the coils are arranged as shown in FIG. 8, the outer shape of the magnet base 1 is an egg shape.

As described above, since the spherical inner space 5 is formed in the magnet base 1 and the static magnetic field magnet 10 is provided along the inner space 5, the coil pattern of the static magnetic field magnet 10 is It becomes spherical. Thereby, the static magnetic field magnet 1
0 can increase the uniformity of the static magnetic field.

Next, a specific configuration of the bed 2 will be described. FIG. 9 is a diagram showing a basic configuration of the bed 2. The bed 2 is composed of the bed base 21, the rotation drive mechanism 20, and the top plate 6. The top plate 6 includes a base 6a and a movable portion 6b,
As shown in the figure, the subject P is placed on the movable part 6b. The rotation drive mechanism 20 drives the top plate 6 to rotate in the horizontal direction. Note that the couch base 21 may be rotated in the horizontal direction, so that the couchtop 6 may be rotationally driven.
In this case, the rotation drive mechanism 20 is unnecessary.

FIG. 10 is a view showing a bed which can be diagnosed and treated by changing the body position of the subject P from a supine state to a sitting state. 2A shows the bed 2 in a supine position, and FIG. 2B shows the bed 2 in a sitting position. In this configuration, the body position of the subject P is changed by changing the shape of the top 6. For this purpose, the movable parts 22 and 23 are provided on the top plate 6. By the operation of the movable part 22, a part of the top plate 6 corresponding to the upper body of the subject P rises in the direction of the arrow M1, and by the operation of the movable part 23, a part of the top plate 6 corresponding to the lower part of the knee of the subject P is moved. As a result, the body position of the subject P can be changed from the supine state to the sitting state. The top plate 6 is driven to rotate in the horizontal direction indicated by the arrow H by the rotation drive mechanism 20.

FIG. 11 is a view showing a bed which can be diagnosed and treated by changing the body position of the subject P from a supine state to a standing state. FIG. 2A shows the bed 2 in the supine state, and FIG. 2B shows the bed 2 in the standing state. In this configuration, the body position of the subject P is changed by raising and lowering the top 6. For this purpose, the movable part 24 is provided on the top plate 6. The top plate 6 is raised in the direction of the arrow V by the operation of the movable unit 24, and the body position of the subject P can be changed from the supine state to the upright state. The rotation of the top plate 6 by the rotation drive mechanism 20 is indicated by an arrow H.
Are driven to rotate in the horizontal direction indicated by.

FIG. 12 is a view showing a horizontal shift mechanism of a subject by sliding a top board, and FIG. 13 is a view showing the same shift mechanism by moving a bed. In the shift mechanism shown in FIG. 12, the movable portion 6b of the top plate 6 is manually or electrically slid in the horizontal direction with respect to the base 6a. Thereby, the subject P is shifted in the horizontal direction indicated by the arrow S from the position (initial state before the shift) shown in FIG. 10A (the initial state before the shift) to the position shown in FIG. be able to.

In the shift mechanism shown in FIG.
The entire bed 2 is moved on the floor 16. This allows
It is possible to shift the subject P in the horizontal direction indicated by the arrow S from the position (initial state before shifting) shown in FIG. 10A (the initial state before the shift) to the position shown in FIG. it can.

As described above, according to the present embodiment, the diagnostic technician or the diagnostician 14 can enter the inner space 5 of the magnet mount 1 through the gap 3 formed in the magnet mount 1, The user can approach the side of the table 6 on which the sample P is placed. Therefore, the above operation can be performed smoothly.

Further, since the spherical inner space 5 is formed in the magnet base 1 and the static magnetic field magnet 10 is provided along the inner space 5, the coil pattern of the static magnetic field magnet 10 becomes spherical. . Therefore, the uniformity of the static magnetic field by the static magnetic field magnet 10 can be improved.

The top plate 6 on which the subject P is placed has the above-mentioned movable mechanism, so that diagnosis and treatment can be performed by changing the body position of the subject P.
The MRI apparatus according to the present embodiment is configured to completely accommodate the bed 2 in the inner space 5 of the magnet gantry 1 to perform diagnosis or treatment. For this reason, compared to the conventional MRI apparatus, the MR
The I-scan room can be reduced (almost halved). However, in this case, it is necessary to make the leakage magnetic field region sufficiently small. The present invention is not limited to the above-described embodiment, and can be implemented with various modifications.

[0036]

As described above, according to the present invention, the uniformity of the static magnetic field is high, and the operator can perform the treatment procedure in a normal body position, so that care for the subject can be performed smoothly. A magnetic resonance imaging apparatus having sufficient openness to the extent possible.

[Brief description of the drawings]

FIG. 1 is a perspective view (bird's eye view) showing the appearance of an open type MRI apparatus according to an embodiment of the present invention.

FIG. 2 is a view showing an outer surface of the magnet gantry 1 according to the embodiment, showing a state immediately before the bed 2 is inserted into an inner space 5;

FIG. 3 is a cross-sectional view at the center of a sphere of the magnet mount 1 according to the embodiment, showing a state when the bed 2 is inserted into an inner space 5.

FIG. 4 is a cross-sectional view at the center of a sphere of the magnet mount 1 according to the embodiment, showing a state in which a top plate 6 is rotated by 90 degrees.

FIG. 5 is a cross-sectional view at the center of a sphere of the magnet mount 1 according to the embodiment, showing a state in which a top plate 6 is shifted with respect to the bed 2;

FIG. 6 is a cross-sectional view showing a specific configuration of the magnet mount 1 according to the embodiment.

FIG. 7 is a cross-sectional view showing the structure of the magnet mount 1 when the leakage magnetic field is reduced by the active shield type coil according to the embodiment.

FIG. 8 is a cross-sectional view showing the structure of the magnet mount 1 when the leakage magnetic field is reduced by the active shield type coil according to the embodiment.

FIG. 9 is a diagram showing a basic configuration of a bed 2 according to the embodiment.

FIG. 10 is a diagram showing a bed capable of performing diagnosis and treatment by changing the body position of the subject P from a supine state to a sitting state.

FIG. 11 is a diagram showing a bed capable of performing diagnosis and treatment by changing the body position of the subject P from a supine state to an upright state.

FIG. 12 is a view showing a horizontal shift mechanism of a subject by sliding a top plate according to the embodiment.

FIG. 13 is a view showing a horizontal shift mechanism of the subject by moving the bed according to the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Magnet stand 2 ... Bed 3 ... Gap 5 ... Inner space 6 ... Top plate 7 ... Passing window 12 ... Connection part 16 ... Floor surface

Claims (4)

[Claims] 1. A static magnetic field generating means which has a substantially spherical inner space capable of accommodating a bed on which a subject is placed and which is arranged in a substantially spherical shape along the inner space and generates a static magnetic field. A magnetic resonance imaging apparatus, wherein a gap for inserting the bed into the inner space is formed in a magnet mount having the same. 2. The bed according to claim 1, wherein the bed includes a top plate on which the subject is placed, and rotation driving means for rotating the top plate with respect to the bed base. Magnetic resonance imaging device. 3. The magnetic resonance imaging apparatus according to claim 1, wherein said static magnetic field generating means includes a plurality of coil bundles arranged discretely along said inner space. 4. The magnetic resonance imaging apparatus according to claim 1, wherein said static magnetic field generating means includes a plurality of coil bundles continuously arranged along said inner space.