JP2005027863A - Magnetic resonance imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide vertical magnetic field type MRI apparatus favorably disposed with a cable for supplying a current to a lower-side gradient magnetic field coil, in a narrow space under a magnet. <P>SOLUTION: This MRI apparatus is provided with a through-hole 104 for disposing the cable of the gradient magnetic field coil in the central part of a lower-side superconducting magnet 102; and means 10-14 guiding the cable 902 from the through-hole 104 to an outer circumferential part of the lower-side superconducting magnet 102 in the opposite side of an imaging space of the lower-side superconducting magnet 102. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vertical magnetic field magnetic resonance imaging apparatus (hereinafter referred to as an MRI apparatus) in which a static magnetic field direction is orthogonal to a body axis direction of a subject, and more particularly to a technique for attaching a gradient magnetic field coil cable.
[0002]
[Prior art]
An MRI apparatus utilizes a nuclear magnetic resonance phenomenon that occurs in the nucleus of atoms that constitute a subject when a subject placed in a uniform static magnetic field (imaging space) is irradiated with a high-frequency magnetic field. By detecting a magnetic resonance signal (hereinafter referred to as an NMR signal) and reconstructing an image using the NMR signal, a magnetic resonance image (hereinafter referred to as an MRI image) representing the physical properties of the subject is obtained. It is. In order to give this imaging position information, a gradient magnetic field is applied in a superimposed manner on the static magnetic field.
[0003]
In recent years, in a vertical magnetic field type MRI apparatus in which the direction of the static magnetic field is orthogonal to the body axis direction of the subject, a concave arrangement space is provided on the opposing surface of the coil container placed opposite to the upper and lower sides, and a gradient magnetic field coil is provided in the space. Has been proposed, and is desirable for reducing the required magnetomotive force (for example, Patent Document 1).
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-99296
FIG. 3A shows an example in which the gradient magnetic field coil cable is pulled out from the outer peripheral portion of the gradient magnetic field generating coil and arranged on the imaging space side of the superconducting magnet in the vertical magnetic field type MRI apparatus described in Patent Document 1. .
In FIG. 3 (a), 101 and 102 are arranged facing each other vertically, and a superconducting magnet (101 is the upper side and 102 is the lower side) having a placement space for the concave gradient magnetic field coils on the upper and lower opposing surfaces of the coil container. , 501 and 502 are gradient magnetic field coils (501 is the upper side, 502 is the lower side) arranged vertically opposite to the concave arrangement space of the superconducting magnets (101 and 102), and 901 and 902 are the gradient magnetic field coils (501 and 502). Gradient coil cables for supplying current (901 is the upper side, 902 is the lower side), 4 is a base for fixing the lower superconducting magnet 102 to the floor, and 105 is the superconducting magnet (101, 102). A refrigerator 106 for cooling the inside of the magnet 106 is a shield room for preventing external noise from entering the space where the MRI apparatus is installed.
[0006]
In FIG. 3 (a), the direction of the static magnetic field is the vertical direction, and the cable of the gradient magnetic field coil has a portion that faces in a direction perpendicular to the direction of the static magnetic field. Lorentz force works. Therefore, in the example of FIG. 3A, it is necessary to firmly fix the cable of the gradient magnetic field coil to the surface of the superconducting magnet in contact with the imaging space side.
[0007]
However, the wiring example of the gradient coil shown in FIG. 3A has the following problems. That is, as shown in FIG. 3A, when the cable of the gradient magnetic field coil is passed through the surface of the superconducting magnet that is in contact with the imaging space, the cable through which a large current flows passes by the subject and adversely affects the subject. Or the cable passes through the vicinity of the shooting space, and the shooting space becomes narrow. The subject is moved from outside on the top of the subject table, but if there is a cable, it may hinder the top. Therefore, it is not preferable to pass the cable of the gradient coil through the imaging space side of the superconducting magnet.
[0008]
Therefore, as shown in FIG. 3B, an example is considered in which a through hole is provided in the center of the superconducting magnet, and the cable of the gradient magnetic field coil is drawn through the through hole to the surface opposite to the imaging space of the superconducting magnet. It is done. In FIG. 3B, reference numerals 103 and 104 denote through holes (103 is the upper side and 104 is the lower side) provided in the central portion of the superconducting magnet (101, 102), and the gradient coil coils (901, 902). Are arranged in the through hole and on the surface opposite to the imaging space of the superconducting magnet.
[0009]
[Problems to be solved by the invention]
However, in the example of FIG. 3 (b), the space between the lower side of the superconducting magnet and the floor surface is a work space in which a person enters and fixes the cable. Therefore, it is necessary to keep the space wide. For this purpose, the height of the base 4 must be increased. In this case, the height of the entire superconducting magnet is increased, and the imaging space and height are also increased. When the height of the imaging space is increased, the subject is placed in the increased imaging space, so that a sense of fear is felt, and access to the subject is difficult for doctors and engineers who handle the apparatus. Furthermore, when the height of the entire superconducting magnet is increased, the upper side of the superconducting magnet needs to have a high ceiling height in the shield room 106 in order to secure a space necessary for the maintenance work of the refrigerator 105. Depending on the situation, it may be necessary to modify the ceiling of the room. Therefore, in the actual apparatus, the height of the lower magnet from the floor surface is lowered. For this reason, it has the subject that the cable fixation of a gradient magnetic field coil is very difficult.
[0010]
An object of the present invention is to provide a vertical magnetic field type MRI apparatus capable of suitably arranging and fixing a cable for supplying a current to a lower gradient magnetic field coil in a narrow space under a magnet. is there.
[0011]
[Means for Solving the Problems]
According to the present invention, a static magnetic field generating means that is arranged vertically opposite to each other across the imaging space and generates a static magnetic field in the vertical direction in the imaging space, and arranged on the imaging space side of the static magnetic field generating means A gradient magnetic field generating means for generating a gradient magnetic field in the imaging space, and a cable for supplying an electric current for generating a gradient magnetic field in the gradient magnetic field generating means, and in the central part of the static magnetic field generating means In the magnetic resonance imaging apparatus provided with a through hole for arranging the cable, the cable is connected from the through hole to the outer peripheral portion of the static magnetic field generating unit on the side opposite to the imaging space of the static magnetic field generating unit. There is provided a magnetic resonance imaging apparatus comprising guide means for guiding, wherein the cable is inserted and fixed along the guide means.
[0012]
According to the invention, there is provided a magnetic resonance imaging apparatus, wherein the guide means includes a rail.
[0013]
According to the present invention, there is provided a magnetic resonance imaging apparatus comprising means for bundling the plurality of cables when the cable is composed of a plurality of cables.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be specifically described below with reference to the accompanying drawings.
FIG. 1 shows a configuration diagram of a vertical magnetic field MRI apparatus according to the present invention. 101 and 102 are superconducting magnets for generating a uniform magnetic field in the imaging space, and are provided with an arrangement space for the concave gradient magnetic field coils on the opposing surface of the coil container arranged opposite to each other (101 is the upper side, 102 is the lower side), 103 and 104 are through holes (103 is the upper side, 104 is the lower side) through the central portion of the superconducting magnet, 2 is the subject, 3 is the subject 2 for placing the subject 2 in the imaging space The top plate 4 is a base for fixing the superconducting magnet to the floor, and 501 and 502 are respectively disposed in the concave arrangement space of the superconducting magnets (101 and 102), and a gradient magnetic field coil for adding positional information to the imaging space , 601 and 602 are high-frequency magnetic field coils for irradiating a proton atom of the subject 2 with a high-frequency magnetic field (601 is on the upper side, 602 is on the lower side), and 7 is a high frequency receiving NMR signal generated from the subject 2. Wave field receiving coils, 801 and 802 are gradient magnetic field coil support bases for fixing the gradient magnetic field coils (501 and 502) (801 is the upper side, 802 is the lower side), 901 and 902 are superconducting from the center of the gradient magnetic field coil This is a gradient coil coil cable that is drawn out of the imaging space through the through holes (103, 104) of the magnet (901 is the upper side, and 902 is the lower side). Further, 15 is a transmission / reception system for converting the NMR signal detected by the high-frequency magnetic field receiving coil 7 into an audio frequency signal, and 16 is an AD for A / D converting the NMR signal converted into the audio frequency signal into a digital signal. A converter 17 is an operation control unit that performs necessary processing on the A / D converted digital signal and reconstructs the image, and 18 is a gradient magnetic field power source. The operation control unit 18 also inclines predetermined voltage and current values through a cable at an appropriate timing by the gradient magnetic field power supply 18 in order to generate a gradient magnetic field for adding position information necessary for imaging to the NMR signal. Control is also applied to the magnetic field coil.
[0015]
The MRI apparatus according to the embodiment of the present invention is further configured as follows to achieve the object of the present invention. That is, 10 and 11 are metal fittings for bundling and inserting the cable (902) of the lower gradient coil, 10 being arranged in the through hole (104) when inserted, and 11 being the lower It is arrange | positioned under a side superconducting magnet. The cable (902) of the lower gradient coil is inserted and bundled into a metal fitting (10, 11) having a hollow portion therein, and an appropriate one is obtained by inserting the metal fitting (10, 11) into the through hole. Placed in position. 12 and 13 are two rails arranged on the lower side of the lower superconducting magnet (102), and when the metal fitting (11) bundled with the cable (902) is inserted from the through hole (104) direction, The metal fitting (11) is slid and moved on the rail, and the cable (902) is preferably arranged below the lower superconducting magnet (102). Reference numeral 14 denotes a metal fitting for defining the direction in which the rails (12, 13) are arranged and fixing the rails (12, 13) to the lower side of the lower superconducting magnet (102).
[0016]
On the other hand, the gradient magnetic field cable (901) passing through the upper side of the upper superconducting magnet 101 has a space for the operator to climb up and fix it on the upper superconducting magnet 101. The magnetic field cable (901) is fixed on the upper superconducting magnet (101).
[0017]
Next, FIG. 2 shows an enlarged view of a mechanism for fixing the cable (902) of the lower gradient coil in the embodiment of the present invention.
Reference numeral 102 denotes a lower superconducting magnet, 802 denotes a lower gradient coil support, 902 denotes a lower gradient coil cable, 10, 11 and 14 denote metal fittings, and 12 and 13 denote rails. However, the A side indicated by the arrow in FIG. 2 is the same as the A side indicated by the arrow in FIG.
[0018]
The procedure for assembling the mechanism for fixing the cable (902) of the lower gradient coil is as follows. First, the gradient coil support base 802 is attached to the lower superconducting magnet 102. The gradient coil support base 802 is provided with fixing holes (not shown) for fixing the rails (12, 13). The rails (12, 13) are fixed to the fixing holes with bolts and nuts. Is done. The rails (12, 13) are arranged in the direction of the metal fitting 14, and are fixed to the lower side of the outermost peripheral portion of the lower superconducting magnet 102 by the metal fitting 14.
[0019]
On the other hand, a cable (902) of the gradient coil is drawn out from the gradient coil, but they are bundled in advance by the metal fittings (10, 11). (However, since the gradient magnetic field required for the MRI apparatus is generally composed of three types corresponding to three-dimensional coordinates of X, Y and Z, the number of gradient magnetic field coils (902) is also different. The number of gradient coil coils (902) is 6 in total including input and output.) And gradient coil, gradient coil cable (902), gradient coil cable ( The metal fittings (10, 11) bundled with 902) are integrally installed at a predetermined position. At this time, the metal fittings (10, 11) bundled with the cables (902) are mounted on the gradient magnetic field coil support (802). And the rails (12, 13) are arranged to slide.
[0020]
The metal fitting (11) is disposed so as to change the direction of a narrow space from the side surface of the gradient coil support (802) onto the rails (12, 13). In order to be able to convert, the metal fitting (11) is composed of a plurality of pieces, each of which has a sufficiently short length in the insertion direction. In addition, the shape of the metal fitting (11) is such that the opposing surfaces of the metal fitting (11) can mesh with each other so that the rail (12, 13) can be suitably slid. In the present embodiment, the cross-sectional shape of the two rails (12, 13) is circular, and two semicircular grooves are provided on the surface of the metal fitting (11) opposite to this, and the interval between them is Is the same as the interval between the two rails (12, 13), and the radius is the same as or slightly larger than the radius of the rail.
[0021]
According to the above embodiment, even if the operator does not enter the lower superconducting magnet (102), the lower gradient coil cable (902) is placed below the lower superconducting magnet (102). A vertical magnetic field MRI apparatus capable of arranging the cable (902) of the lower gradient magnetic field coil in a narrow space under the magnet while the height of the imaging space is an appropriate height. Can be provided. The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
[0022]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a vertical magnetic field MRI apparatus capable of suitably arranging a cable for supplying a current to the lower gradient coil in a narrow space under the magnet.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a vertical magnetic field MRI apparatus according to the present invention.
FIG. 2 is an enlarged view of a mechanism for fixing a cable of a lower gradient coil.
FIG. 3 is a wiring array of a gradient coil coil cable in a conventional vertical magnetic field type MRI apparatus;
[Explanation of symbols]
10, 11, 14 ... metal fittings 12, 13 ... rail

Claims (1)

A static magnetic field generating means for vertically generating a static magnetic field in the imaging space with the imaging space interposed therebetween, and a static magnetic field generating means disposed on the imaging space side of the static magnetic field generating means, A gradient magnetic field generating means for generating a gradient magnetic field; and a cable for supplying a current to generate a gradient magnetic field to the gradient magnetic field generating means, and the cable is disposed in the center of the static magnetic field generating means In the magnetic resonance imaging apparatus in which a through hole is provided, a guide unit that guides the cable from the through hole to an outer peripheral portion of the static magnetic field generation unit on the side opposite to the imaging space of the static magnetic field generation unit is provided. The magnetic resonance imaging apparatus is characterized in that the cable is inserted and fixed along the guide means.

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