JP2011131009A - Magnetic resonance imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an MRI apparatus which has a large inner space and a gradient magnetic field coil with superior cooling capacity. <P>SOLUTION: A gradient magnetic field coil comprises a tubular conductor 12 with flat inner diameter and a cooling tube 10. The tubular conductor includes spiral slit. The cooling tube 10 is arranged so as to cover a peripheral area of the tubular conductor, at least a part of an area except for a prescribed area with width 2T centering on a position where the major axis of the inner diameter of the tubular conductor and the tubular conductor cross. Thus even a gradient magnetic field coil with a flat inner diameter such as an oval shape can be efficiently cooled. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a magnetic resonance imaging (hereinafter referred to as “MRI”) apparatus, and more particularly to a magnetic resonance imaging apparatus including a gradient magnetic field coil that generates a high-intensity gradient magnetic field and has improved openness.

  In an MRI apparatus using a cylindrical magnetic field generator, it is desired to increase the inner diameter of the gradient magnetic field coil in order to secure the maximum space for the subject and reduce the feeling of blockage.

  Patent Document 1 discloses an MRI apparatus in which the inner diameter of a gradient magnetic field coil is elliptical and the inner diameter in the horizontal direction is widened.

  Patent Document 2 discloses an apparatus in which a gradient magnetic field coil that is divided in the vertical direction and is open on the side is arranged inside a cylindrical static magnetic field generating coil. Thereby, the diameter of the space where the subject is arranged has an elliptical shape in which the horizontal direction is larger than the height direction. Further, a configuration is also disclosed in which the gradient magnetic field coil has an active shield structure, and the gradient magnetic field coil, the shield coil, and the cooling channel are arranged.

  Patent Document 3 discloses a gradient magnetic field coil that also serves as a cooling conduit by providing a hollow region in a conductor of a gradient magnetic field coil and flowing a refrigerant.

JP 2001-327478 A Japanese Patent Laid-Open No. 10-179552 JP 2005-230543 JP

  The gradient coil design requires an electromagnetic design in which a gradient magnetic field with a predetermined strength is formed in the internal space (inside the bore) where the subject is placed, and conversely, no leakage magnetic field is generated outside. It is. At the same time, it is necessary to provide a cooling mechanism for suppressing heat generation caused by flowing current through the gradient coil.

  In the gradient magnetic field coil having an inner diameter of an ellipse, by making the thickness in the major axis direction thinner than that in the minor axis direction, a wider space for the subject can be secured in the major axis direction. However, when the thickness of the gradient magnetic field coil is reduced, the cooling pipe in the gradient magnetic field coil must be thinned or omitted, and it is difficult to ensure a sufficient cooling effect. Therefore, it becomes difficult to flow a large current, and it becomes difficult to design a gradient coil that generates a large gradient magnetic field.

  The gradient magnetic field coil described in Patent Document 2 has a configuration in which the gradient magnetic field coil is vertically separated and opened in the horizontal direction. Therefore, there is no problem of ensuring the cooling effect of the gradient magnetic field coil in the major axis direction. For this reason, the technology of the cooling channel disclosed in Patent Document 2 cannot be directly applied to the elliptical gradient coil. In addition, the coil that also serves as the cooling conduit described in Patent Document 3 needs to increase the hollow area of the conduit, that is, the conductor size, in order to increase the flow rate of the refrigerant. Have difficulty.

  An object of the present invention is to provide an MRI apparatus including a gradient magnetic field coil having a large internal space and excellent cooling ability.

  In order to achieve the above object, according to the present invention, the following MRI apparatus is provided. That is, a magnetic resonance imaging apparatus having a static magnetic field generation unit that generates a static magnetic field space and a gradient magnetic field coil that is arranged inside the static magnetic field generation unit and applies a gradient magnetic field to the static magnetic field space, Includes a cylindrical conductor having a flat inner diameter and a cooling pipe. The cylindrical conductor is provided with a spiral slit. The cooling pipe is an outer peripheral region of the cylindrical conductor, and is at least one of the regions excluding the region having a predetermined width around the position where the major axis of the inner diameter of the cylindrical conductor intersects the cylindrical conductor. It arrange | positions so that a part may be covered. By disposing the cooling pipe in such a region, the gradient magnetic field coil having a flat shape such as an elliptical inner diameter can be efficiently cooled.

  The cooling pipe can be configured to be arranged so as to cover only a region having a predetermined length in the central axis direction of the cylindrical conductor from the openings at both ends of the cylindrical conductor. Thereby, the area | region where the emitted-heat amount near the opening of the both ends of a cylindrical conductor can be cooled efficiently.

  For example, the flat cylindrical conductor has an inner diameter that is elliptical.

  For example, the cylindrical conductor is configured to be covered with an insulating material, and at least a part of the insulating material is configured such that particles of a material having a higher thermal conductivity than the insulating material are mixed. . By improving the thermal conductivity of the insulating material, the cylindrical conductor in the region where the cooling pipe is not arranged can be efficiently cooled. The region of the insulating material in which the particles are mixed is, for example, a region having a predetermined width in the circumferential direction centering on a position where the long axis where the cooling pipe is not disposed and the cylindrical conductor intersect. The region can be at least a predetermined length in the direction of the central axis from the opening of the conductor. As particles having a high thermal conductivity, any of silica, alumina, aluminum nitride, and boron nitride can be used.

  It is possible to arrange shim coils for adjusting the static magnetic field uniformity between the cooling pipes arranged at both ends of the cylindrical conductor.

  The gradient magnetic field coil may be configured to include a main coil that generates a gradient magnetic field and a shield coil that prevents the gradient magnetic field from leaking to the static magnetic field generation unit side. In this case, at least the main coil is configured to include a cylindrical conductor having a flat inner diameter. The cooling pipe can be disposed between the main coil and the shield coil.

  According to the present invention, even if the gradient magnetic field coil has a flat shape such as an ellipse with an inner diameter, the cooling pipe is not arranged in the long axis direction with a small thickness. Efficiency can be improved. In addition, by utilizing the heat conductivity of the gradient magnetic field coil conductor, the thin portion on the long axis can be cooled only by the cooling pipe arranged on the short axis, so that a large current is applied to the gradient magnetic field coil. It is possible to flow, and a high magnetic field strength can be obtained.

The block diagram which shows the partial structure of the MRI apparatus of embodiment. The side view which shows the partial shape of the opening part of the gradient magnetic field coil 2 of the MRI apparatus of embodiment. XY sectional drawing of the gradient coil 2 of FIG. FIG. 3 is a YZ sectional view of the gradient coil 2 of FIG. 2. Explanatory drawing which shows the structure of the Y main coil 12 and the Y shield coil 32 of the MRI apparatus of embodiment. FIG. 6 is a top view when a part of the Y main coil 12 of FIG. FIG. 6 is a YZ side view of the Y main coil 12 of FIG. 5. Explanatory drawing which shows the state which expand | deployed some X main coils, Y main coils, and the cooling pipe of the gradient magnetic field coil of FIG. Explanatory drawing which shows the state which expand | deployed the X main coil of the gradient magnetic field coil of the MRI apparatus of 3rd Embodiment, the Y main coil, and a part of cooling pipe in planar shape. Explanatory drawing which shows the state which expand | deployed some X main coils, Y main coils, and a cooling pipe of the gradient magnetic field coil of the MRI apparatus of 4th Embodiment planarly. Explanatory drawing which shows the state which expand | deployed a part of X main coil, Y main coil, and cooling pipe of the gradient magnetic field coil of another example of the MRI apparatus of 4th Embodiment planarly. YZ sectional drawing of the gradient coil of the MRI apparatus of 5th Embodiment. The perspective view of the cooling pipe 10 of the gradient magnetic field coil of 5th Embodiment. The YZ sectional view of the gradient magnetic field coil of another embodiment.

  An MRI apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment of the invention, and the repetitive description thereof is omitted.

(First embodiment)
FIG. 1 shows a partial configuration of the MRI apparatus of the first embodiment. The MRI apparatus includes a static magnetic field generator 1 that forms a uniform static magnetic field region 5, a gradient magnetic field coil 2 that applies a gradient magnetic field in each direction of the X, Y, and Z axes to the uniform static magnetic field region 5, and a uniform static magnetic field region A subject in 5 is provided with a high-frequency magnetic field coil 3 and a bed 4 for a high-frequency magnetic field. Here, the static magnetic field generator 1 uses a cylindrical one with the central axis directed in the Z-axis direction. Any of a superconducting magnet, a normal conducting magnet, and a permanent magnet may be used. An unillustrated subject lies on the bed 4 and is disposed in the uniform magnetic field region 5. The gradient magnetic field coil 2 is fixed between the static magnetic field generator 1 and the uniform magnetic field region 5. The high-frequency magnetic field coil 3 is fixed between the gradient magnetic field coil 2 and the uniform magnetic field region 5.

  In addition, although not shown in FIG. 1, the MRI apparatus includes a receiving coil, a shim coil, a gradient magnetic field power source, a transmission system, a reception system, a signal processing system, a sequencer, And an operation unit.

  The gradient magnetic field power supply supplies a drive current to the gradient magnetic field coil 2 at a predetermined timing to generate a gradient magnetic field. The transmission system supplies a high-frequency pulse to the high-frequency magnetic field coil 3 and generates a high-frequency magnetic field pulse that causes nuclear magnetic resonance (NMR) in the nuclear spins of atoms constituting the living tissue of the subject. The receiving system detects the NMR signal from the subject received by the receiving coil and sends it to the signal processing system. The signal processing system performs signal processing on the signal received from the receiving system and performs image reconstruction. The sequencer controls the gradient magnetic field power supply, transmission system, and reception system, repeatedly irradiates and applies high frequency magnetic field pulses and gradient magnetic field pulses to the subject at a predetermined timing, and receives a pulse sequence for receiving NMR signals at a predetermined timing. Let it run. The operation unit receives input from the operator of various control information.

  Hereinafter, the configuration of the inclined ground coil 2 will be described in detail with reference to FIG.

  As shown in FIG. 2, the gradient magnetic field coil 2 has a cylindrical outer surface in order to secure a wide internal space in which the subject is placed in the horizontal direction (X direction). An elliptical cylinder with its long axis oriented in the X direction. Therefore, the thickness of the inclined ground coil 2 is thinner in the horizontal direction than in the vertical direction.

  The gradient magnetic field coil 2 has three types of coils for generating gradient magnetic fields in the X, Y, and Z directions, respectively, as shown in FIG. 3 for the XY sectional view and FIG. 4 for the YZ sectional view (AA sectional view). (X coils 11, 31, Y coils 12, 32, Z coils 13, 33), a cooling pipe 10, and an insulating member 15 for fixing each coil and the cooling pipe 10 together.

  The three types of coils include a main coil that applies a gradient magnetic field to the imaging space, and a shield coil that generates a reverse magnetic field so that the magnetic field generated by the main coil does not leak to the static magnetic field magnet side. Specifically, the X coil includes an X main coil 11 and an X shield coil 31, the Y coil includes a Y main coil 12 and a Y shield coil 32, and the Z coil includes a Z main coil 13 and a Z shield. Including the coil 33. These are the Z main coil 13, X main coil 11, Y main coil 12, cooling pipe 10, Z shield coil 33, X shield coil 31, Y shield coil 32 in this order from the imaging space (uniform static magnetic field region 5) side. Are stacked.

  The insulating member 15 is filled between the coils to which a high voltage is applied and between the turns of each coil, and while ensuring insulation, these are consolidated together to maintain the shape. Moreover, as an insulating material, it is inorganic materials, such as resin, such as epoxy, and glass, Comprising: A nonmagnetic material can be used.

  Each of the X coils 11 and 31 and the Y coils 12 and 32 is manufactured by slitting a conductor plate. On the other hand, the Z coils 13 and 33 have a structure in which a tubular conductor is wound around the Z axis. The gradient coil 2 is cooled by passing a cooling medium through the Z coils 13 and 33. As a material of the conductor constituting each coil, a material having a high electric conductivity is desirable, for example, copper is preferable.

  The cooling pipe 10 is disposed only in a predetermined region determined in consideration of the coil patterns of the X coils 11 and 31 and the Y coils 12 and 32. Thereby, the temperature rise of the gradient magnetic field coil 2 is suppressed while keeping the internal space of the gradient magnetic field coil 2 wide.

  FIG. 5 shows a schematic configuration diagram of the Y coil. As shown in FIG. 5, the Y coil is composed of a Y main coil 12 and a Y shield coil 32, each of which is composed of four conductors. Each of the four conductors is formed with slits having a predetermined vortex pattern. In FIG. 5, the four conductors are illustrated with gaps between them, but in reality, the four conductors are connected at the ends, and the Y main coil 12 forms an elliptical cylinder on the inner side surface. The Y shield coil 32 forms a cylinder. An ellipse is a shape having a focal point defined by a major axis and a minor axis.

  FIG. 6 illustrates a vortex pattern formed by a slit in one conductor of the Y main coil 12 in a state where the conductor is developed on a plane. In FIG. 6, the pattern edge 22 between adjacent turns is shown as one line, but in reality, a slit having a predetermined width is formed between the turns. Although omitted in FIG. 6, a spiral pattern is formed by connecting adjacent turns, and a lead line from the center is provided.

FIG. 7 shows a side view of the entire Y main coil 12 formed by connecting four conductors. As shown in FIG. 7, two pairs of vortex patterns facing in the Y-axis direction are arranged side by side in the Z-axis direction. The vortex pattern is designed to generate a Y-direction gradient magnetic field with a predetermined specification. Conductor width turn located within a range of a length L _h from the end of the Z-axis direction as is apparent Y main coil 12 from FIG. 7 is the narrowest in the entire vortex. In consideration of the fact that the magnetic flux spreads when the magnetic flux leaks from the opening of the gradient coil 2 to the outside, the magnetic flux density generated by the coil in the vicinity of the opening is made larger than the central portion in the Z-axis direction of the cylinder. Because. Thereby, the area | region where the gradient magnetic field intensity in a cylinder is constant is ensured as widely as possible.

Turn ranging Thus Y length from the end of the Z-axis direction in the main coil 12 L _h is conductor width is narrow. Moreover, since the X and Y main coils 11 and 12 are elliptical and the internal space is wider than the cylindrical one, the total number of turns is increased compared to the cylindrical one, and the conductor width is cylindrical. Narrower than things. Therefore, turn the range of length L _h is greater electrical resistance than a cylindrical coil, the current density is high, the amount of heat generated is proportional to the electrical resistance as is generally known, current It increases in proportion to the square of. Assuming that the coil axis length in the Z direction is L _coil , this L _h is approximately 0.1 to 0.15 × L _coil , and it is known that the amount of heat generation is about three times higher than other regions.

On the other hand, the X main coil 11 is a coil obtained by rotating the Y main coil by 90 °. Thus, it concentrates from the end of the same as Z-axis direction highly exothermic region of X main coil 11 also Y main coil 12 in the range of length L _h.

Therefore, in the present embodiment, the cooling pipe 10 is arranged in a range of length L _h from both ends in the Z-axis direction of the X main coil 11 and the Y main coil 12 as shown in FIGS. Cool the heat generating area. Specifically, as shown in FIG. 8, a vortex pattern of the Y main coil 12 and the X main coil 11 and a plan development view of the cooling pipe 10 (range from 0 ° (X axis direction) to 180 ° in FIG. 2). the cooling tube 10 in the region of the length L _h from the end of the Z-axis direction, they are arranged in a serpentine shape. In FIG. 8, the dotted line indicates the pattern edge 21 of the X main coil 11.

Cooling pipe 10 as shown in FIG. 8, but for the Z-axis direction is arranged in the region of the length L _h from the end, for the circumferential direction of the X and Y main coil 11, 12, 0 of FIG. 2 ° They are not arranged in a range of a predetermined width T (total width 2T) on both sides centering on (x-axis direction) and 180 °. In this region, heat is transferred along the path of the arrow shown in FIG. 8 by the heat conduction of the conductors constituting the X and Y main coils 11 and 12, and is transferred to the cooling pipe 10. Since the thermal conductivity of copper, which is the conductor material, is as high as about 390 W / m ° C., the heat generated in the region having a width of 2T can be sufficiently conducted to the cooling pipe 10 by the heat conduction of the conductor. The width 2T and the length L _h are inclined below the desired temperature in consideration of the heat generation of the X and Y main coils 11 and 12, the heat conductivity of the conductor, and the flow rate / temperature of the refrigerant in the cooling pipe 10. The length is designed so that the magnetic field coil 2 can be maintained.

  The refrigerant inside the cooling pipe 10 is supplied from a chiller outside the inspection room. It is also possible to connect the cooling pipe 10 in parallel with the Z coils 13 and 33 that also serve as a conduit.

  Thus, in this embodiment, since the cooling pipe 10 is disposed in addition to the Z coil 13 that also serves as a cooling conduit, the high heat generating portions of the X and Y main coils 11 and 12 are effectively cooled. be able to. For this reason, the X and Y main coils 11 and 12 with a large internal space and a large number of turns and a narrow conductor width of the turns, compared to the cylindrical type, have a high cooling capacity, so a large current is consumed. Can be supplied. Therefore, it is possible to realize the gradient magnetic field coil 2 having a wide internal space and capable of applying a large gradient magnetic field.

  Moreover, in the present embodiment, the cooling pipe 10 is not disposed in the range of the predetermined width 2T centering around 0 ° and 180 ° in the circumferential direction, and therefore, as shown in FIG. Further, the thickness of the gradient coil 2 in the 180 ° direction can be reduced. That is, the thickness of the insulating member 15 between the X, Y, Z main coils 11, 12, 13 and the X, Y, Z shield coils 31, 32, 33 can be made smaller than the diameter of the cooling pipe 10. it can. By arranging the cooling tube 10 as described above, the thickness of the gradient magnetic field coil 2 in the major axis direction is made as thin as possible, the inner diameter in the major axis direction is made as large as possible, and the space in which the subject is arranged is increased. It can be enlarged horizontally.

Further, as shown in FIG. 4, by arranging the cooling pipe 10 only in the range of the length L _h from both ends of the Z axis, the shim coil 14 is arranged in the central space sandwiched between the two cooling pipes 10. It becomes possible. The shim coil 14 is a coil for compensating for the static magnetic field uniformity due to the difference in magnetic susceptibility of the imaging region. Thereby, compared with the case where the shim coil 14 is arranged separately from the gradient magnetic field coil 2, a large imaging region can be secured.

  As the structure of the shim coil 14, a known structure can be used. For example, it is manufactured by winding a conductive wire, slitting a copper plate, or etching a substrate, and usually a current of several A is applied.

(Second Embodiment)
An MRI apparatus according to the second embodiment will be described.

  In the MRI apparatus of the second embodiment, particles having a higher thermal conductivity than the insulating member, such as silica, alumina, aluminum nitride, boron nitride, etc., are dispersed in at least a part of the insulating member 15 of the gradient coil 2. ing. Other configurations are the same as those of the first embodiment, and thus description thereof is omitted.

Area for arranging the insulating member 15 the particles are dispersed, at least 0 ° (X axis direction) in FIG. 2 and 180 ° about the width 2T, is an area of length L _h from the end in the Z-axis direction . An insulating member 15 in which particles are dispersed is disposed between the X, Y, and Z main coils 11, 12, and 13 in this region. It is also possible to arrange the insulating member 15 in which particles are dispersed between the turns of the coil. Not this region only, especially heating of and the insulating member 15 the entire area of the Z length from axial end L _h is a large part, also be configured as the particles are dispersed throughout the insulating member 15 Is possible.

  In the present embodiment, since the efficiency of transmitting the heat generated in the region having a width of 2T around 0 ° and 180 ° to the cooling pipe 10 can be increased, the cooling efficiency is increased. Accordingly, the width 2T can be set larger than that in the first embodiment, and the gradient magnetic field coil 2 can be further thinned, so that the internal space can be increased.

(Third embodiment)
An MRI apparatus according to a third embodiment of the present invention will be described.

In the first embodiment, a region of the cooling pipe 10 Z length from axial both ends L _h as shown in FIG. 8, the width in the circumferential direction 0 ° (X-axis direction) and 180 centered ° 2T However, in the third embodiment, as shown in FIG. 9, the cooling pipe 10 is arranged in the entire area excluding the area having a width of 2T around 0 ° and 180 °. . The Z-axis direction is arranged in the entire region of the coil axis length Lcoil. Other configurations are the same as those of the first embodiment, and thus description thereof is omitted.

  As shown in FIG. 9, the cooling pipe 10 is arranged in the entire region in the Z-axis direction, so that the cooling efficiency is further increased, so that the current supplied to the gradient coil can be increased. Therefore, the MRI apparatus of the present embodiment can cope with a sequence that requires a high gradient magnetic field while ensuring a large space for the subject.

(Fourth embodiment)
An MRI apparatus according to a fourth embodiment will be described.

In the fourth embodiment, the cooling pipe 10 is arranged in the same region as that of the first embodiment, but the shape of the cooling pipe 10 is different from that of the first embodiment. FIG. 10 shows an example in which the cooling pipe 10 has a shape meandering in the Z-axis direction. FIG. 11 shows an example in which the cooling pipe 10 is wound in a spiral shape. Located the region of the cooling pipe 10 as in the first embodiment, a region of length L _h from both ends in the Z axis direction, in the circumferential direction 0 ° (X-axis direction) and 180 centered ° This is an area excluding an area having a width of 2T. Further, except for the structure of the cooling pipe 10, it is the same as in the first embodiment.

  Even when the cooling pipe 10 is structured as shown in FIGS. 10 and 11, the area where the cooling pipe 10 is arranged is made the same area as in the first embodiment, so that the MRI of the first embodiment is performed. Functions and effects similar to those of the apparatus can be obtained.

  Further, the cooling pipe 10 of FIGS. 10 and 11 is the entire area in the Z-axis direction (the entire coil axis length Lcoil) as in the second embodiment, and the circumferential direction is 0 ° and 180 °. It is also possible to arrange in a region excluding the region of width 2T from the center.

(Fifth embodiment)
An MRI apparatus according to a fifth embodiment will be described.

  In the fifth embodiment, the shape of the cooling pipe 10 is different from that of the first embodiment. FIG. 12 is a YZ sectional view of the gradient magnetic field coil 2, and FIG. 13 is a perspective view of the cooling pipe 10. The cooling pipe 10 of the present embodiment is configured to be wound in a ring shape that circulates in the circumferential direction, except for a region having a width of 2T around 0 ° (X axis) and 180 °. The length Lh in the Z-axis direction can be designed to an arbitrary length depending on the number of windings of the cooling pipe 10 and the winding interval. It is also possible to arrange the cooling pipe 10 over the entire length in the Z-axis direction.

  By making the cooling pipe 10 into a ring shape as shown in FIGS. 12 and 13, the cooling pipe 10 has a position close to the elliptical X, Y, Z main coils 11, 12, 13 and the cylindrical X, Y, Since it can arrange | position in the position close | similar to Z shield coil 31,32,33, main coil 11,12,13 and shield coil 31,32,33 can be cooled simultaneously.

  In FIG. 12, the stacking order of the shield coils is arranged in the order of X, Y, Z shield coils 31, 32, 33 from the side closer to the cooling pipe 10. As a result, the X and Y shield coils 31 and 32 can be cooled by being sandwiched between the cooling pipe 10 and the Z shielding coil 33 that also serves as the cooling pipe. As in the first embodiment, the main coils are stacked so that the X and Y main coils 11 and 12 are sandwiched by the cooling main tube 10 and the Z main coil 13 that also serves as a cooling tube for cooling. With such a structure, not only the main coil but also the shield coil can be efficiently cooled, and a large gradient magnetic field can be generated by supplying a large current to the gradient coil 2.

  The stacking order of the main coils is not limited to the stacking order of FIGS. 4 and 12 of the first and fifth embodiments, and the cooling pipe 10 and the X and Y main coils 11 and 12 as shown in FIG. It is also possible to adopt a configuration in which a Z main coil 13 that also serves as a cooling pipe is disposed between the two.

  Further, in each of the above-described embodiments, the Z main coil 13 and the Z shield coil 33 have a structure that also serves as a cooling pipe, but the present invention is not limited to this configuration, and as the Z coils 13 and 33, It is also possible to use wires that are not conduits. Also in this case, since the cooling pipe 10 is disposed in the present invention, the high temperature region of the X and Y coils can be efficiently cooled.

  In each of the embodiments described above, the configuration in which the main coil of the gradient magnetic field coil 2 is formed in an elliptical cylinder and the shield coil is cylindrical has been described, but the present invention is limited to an example in which the shield coil is cylindrical. It is not something. The shield coil can also have an elliptical cylindrical shape.

DESCRIPTION OF SYMBOLS 1 ... Static magnetic field generator, 2 ... Gradient magnetic field coil, 3 ... High frequency magnetic field coil, 4 ... Bed, 5 ... Uniform magnetic field area (imaging space), 10 ... Cooling pipe, 11 ... X main coil, 12 ... Y main coil, 13 ... Z main coil, 14 ... Sim coil, 15 ... Insulating material, 21 ... X main coil pattern edge, 22 ... Y main coil pattern edge, 31 ... X shield coil, 32 ... Y shield coil, 33 ... Z shield coil

Claims (8)

A magnetic resonance imaging apparatus comprising: a static magnetic field generation unit that generates a static magnetic field space; and a gradient magnetic field coil that is disposed inside the static magnetic field generation unit and applies a gradient magnetic field to the static magnetic field space,
The gradient magnetic field coil includes a cylindrical conductor having a flat inner diameter and a cooling pipe, and the cylindrical conductor includes a spiral slit,
The cooling pipe is an outer peripheral region of the cylindrical conductor, excluding a region having a predetermined width centering on a position where the long axis of the inner diameter of the cylindrical conductor intersects the cylindrical conductor. A magnetic resonance imaging apparatus, wherein the magnetic resonance imaging apparatus is disposed so as to cover at least a part of the region.   2. The magnetic resonance imaging apparatus according to claim 1, wherein the cooling tube covers only a region having a predetermined length in a central axis direction of the cylindrical conductor from openings at both ends of the cylindrical conductor, respectively. A magnetic resonance imaging apparatus, wherein   The magnetic resonance imaging apparatus according to claim 1, wherein an inner diameter of the flat cylindrical conductor is an ellipse.   The magnetic resonance imaging apparatus according to claim 1, wherein the cylindrical conductor is covered with an insulating material, and the insulating material in at least a part of the region is made of particles of a material having a higher thermal conductivity than the insulating material. A magnetic resonance imaging apparatus characterized by being mixed.   5. The magnetic resonance imaging apparatus according to claim 4, wherein the region of the insulating material in which the particles are mixed is centered on a position where the long axis where the cooling pipe is not disposed and the cylindrical conductor intersect. A magnetic resonance imaging apparatus characterized in that the region has a predetermined width.   6. The magnetic resonance imaging apparatus according to claim 4, wherein the particles having a high thermal conductivity are any one of silica, alumina, aluminum nitride, and boron nitride.   3. The magnetic resonance imaging apparatus according to claim 2, wherein shim coils for adjusting the static magnetic field uniformity are arranged between the cooling tubes respectively arranged at both ends of the cylindrical conductor. Magnetic resonance imaging apparatus. The magnetic resonance imaging apparatus according to claim 1, wherein the gradient magnetic field coil includes a main coil that generates the gradient magnetic field and a shield coil that prevents the gradient magnetic field from leaking to the static magnetic field generation unit side. ,
The magnetic resonance imaging apparatus, wherein at least the main coil includes a cylindrical conductor having a flat inner diameter, and the cooling tube is disposed between the main coil and the shield coil.

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