RF coil, bed device, and magnetic resonance imaging device

Abstract

To provide an RF coil, a bed device, and a magnetic resonance imaging device capable of preventing reduction of SNR regardless of the body shape of a subject, facilitating setting, and improving a workflow.SOLUTION: An RF coil according to the present disclosure is configured so that a first outer shell region which is formed of multiple elements of a first fixing belt arranged on a top plate where a subject is placed has a tapered shape as it is separated from a first end side of the top plate, and a second outer shell region which is formed of multiple elements of a second fixing belt arranged on the top plate has a tapered shape as it is separated from a second end side of the top plate. The first outer shell region and the second outer shell region are positioned so that their phases in a longitudinal direction are offset from each other.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to an RF coil, a bed apparatus, and a magnetic resonance imaging apparatus, and particularly to a technique for fixing an RF coil to a subject.

Background Art

[0002] A magnetic resonance imaging apparatus (hereinafter referred to as an MRI (Magnetic Resonance Imaging) apparatus) receives a magnetic resonance signal generated in a subject and reconstructs this received signal to obtain a magnetic resonance image. In such an MRI apparatus, it is necessary to fix an RF (Radio Frequency) coil in which a plurality of elements for receiving a magnetic resonance signal are arranged to the subject.

[0003] Patent Document 1 discloses an RF coil unit for MRI including a plurality of RF coils formed to undertake at least one of transmission and reception of a high-frequency magnetic field for MRI, and an output impedance adjustment circuit for adjusting the output impedance of the plurality of RF coils.

[0004] Patent Document 2 discloses an RF coil that receives a magnetic resonance signal from a subject with a plurality of elements including a first element that can be expanded and contracted and a second element that can be expanded and contracted.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] It is preferable that the elements of the RF coil be arranged without gaps near the subject. However, in a one-piece RF coil with a fixed size, it may not be possible to cover variations in the size of the subject. In this case, there is a problem that the SNR (Signal to Noise Ratio) of the magnetic resonance signal cannot be sufficiently obtained in the range that cannot be covered by the elements.

[0007] In addition, a one-piece RF coil with a fixed size has a problem that the number of settings is large and the workflow is degraded.

[0008] On the other hand, the techniques described in Patent Document 1 and Patent Document 2 cannot solve these problems.

[0009] The present invention has been made in view of such circumstances, and an object thereof is to provide an RF coil, a bed apparatus, and a magnetic resonance imaging apparatus that can prevent a decrease in SNR regardless of the body shape of the subject, and that are easy to set up and can improve the workflow.

Means for Solving the Problems

[0010] To achieve the above object, an RF coil according to a first aspect of the present disclosure is an RF (Radio Frequency) coil for a magnetic resonance imaging apparatus including a top plate on which a subject is placed along a longitudinal direction, and includes a first fixing belt disposed on the top plate and attached to the subject from a first end side in a width direction orthogonal to the longitudinal direction of the top plate toward a second end side opposite to the first end side, and a plurality of elements disposed on the first fixing belt, a first coil unit; a second fixing belt disposed on the top plate and at least partially overlapped with the first fixing belt and attached to the subject from the second end side of the top plate toward the first end side, and a plurality of elements disposed on the second fixing belt, a second coil unit; and a first outer contour region formed by the plurality of elements of the first coil unit has a tapered shape as it is spaced apart from the first end side of the top plate, a second outer contour region formed by the plurality of elements of the second coil unit has a tapered shape as it is spaced apart from the second end side of the top plate, and the first outer contour region and the second outer contour region are RF coils arranged with their longitudinal phases shifted from each other.

[0011] According to the RF coil according to the first aspect, it is possible to prevent a decrease in SNR regardless of the body shape of the subject, and the setting is easy and the workflow can be improved.

[0012] An RF coil according to a second aspect of the present disclosure is the RF coil according to the first aspect, wherein the plurality of elements of the first coil unit form a plurality of first outer contour regions, the plurality of elements of the second coil unit form a plurality of second outer contour regions, and it is preferable that the plurality of first outer contour regions and the plurality of second outer contour regions are alternately arranged along the longitudinal direction.

[0013] An RF coil according to a third aspect of the present disclosure is the RF coil according to the first aspect or the second aspect, wherein it is preferable that the plurality of elements each have a smaller diameter as they are spaced apart from the top plate.

[0014] The RF coil according to the fourth aspect of the present disclosure is the RF coil according to the third aspect, and it is preferable that the plurality of elements are arranged at positions where the lines connecting the centers are parallel to the width direction.

[0015] The RF coil according to the fifth aspect of the present disclosure is the RF coil according to the third aspect, and it is preferable that the plurality of elements of the first coil unit are arranged with their ends aligned on one side in the longitudinal direction, and the plurality of elements of the second coil unit are arranged with their ends aligned on the other side in the longitudinal direction.

[0016] The RF coil according to the sixth aspect of the present disclosure is the RF coil according to the fifth aspect, and it is preferable that the first fixing belt and the second fixing belt are provided with guide lines for arranging the other side of the first outer region and one side of the second outer region adjacent to each other in a plan view when the first fixing belt and the second fixing belt are attached to the subject.

[0017] The RF coil according to the seventh aspect of the present disclosure is the RF coil according to the first aspect or the second aspect, and it is preferable that the plurality of elements each have a constant diameter and are arranged such that the number per unit area decreases as they are separated from the top plate.

[0018] The coil unit according to the eighth aspect of the present disclosure is the RF coil according to any one of the first aspect to the seventh aspect, and it is preferable that the first fixing belt is provided with a guide display indicating an appropriate range of a position where the second fixing belt overlaps.

[0019] The RF coil according to the ninth aspect of the present disclosure is the RF coil according to any one of the first aspect to the eighth aspect, and it is preferable that the first fixing belt and the second fixing belt are provided with the first surface and the second surface of a pair of surface fasteners whose first surface and second surface engage at a position where they contact each other when attached to the subject.

[0020] In order to achieve the above object, a bed device according to a tenth aspect of the present disclosure is a bed device including a top plate on which a subject is placed and an RF coil according to any one of the first aspect to the ninth aspect.

[0021] To achieve the above object, a magnetic resonance imaging apparatus according to the 11th aspect of the present disclosure includes a bed apparatus according to the 10th aspect, a gantry including a magnetic field generation source and having an opening, and a drive mechanism that moves a top plate in the longitudinal direction and enters and exits the opening of the gantry. It is a magnetic resonance imaging apparatus provided with.

Effect of the Invention

[0022] According to the present invention, it is possible to prevent a decrease in SNR regardless of the body type of the subject, and the setting is easy and the workflow can be improved.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

[0024] Hereinafter, preferred embodiments of an RF coil, a bed device, and an MRI device according to the present disclosure will be described with reference to the accompanying drawings. In this specification, the same reference numerals are assigned to the same components, and redundant descriptions are omitted as appropriate.

[0025] [Conventional Device] FIG. 1 is a perspective view showing an example of an MRI device 10. As shown in FIG. 1, the MRI device 10 includes a gantry 12 and a bed 16. The gantry 12 has a bore 14 which is an inspection (imaging) space on a cylinder. Further, an MRI magnet as a magnetic field generation source and various other coils are disposed in the gantry 12.

[0026] The bed 16 is installed on the front side of the gantry 12 facing the bore 14. The bed 16 includes a top plate 18. A subject 20 is placed on the top plate 18 along the longitudinal direction. The top plate 18 is configured to be movable in the X direction which is the width direction of the top plate 18, the Y direction which is the vertical direction, and the Z direction which is the longitudinal direction orthogonal to the width direction of the top plate 18.

[0027] The MRI apparatus 10 includes a drive mechanism (not shown) that moves the top plate 18 in the Z direction and causes it to enter and exit the opening of the gantry 12. By moving the top plate 18 within the bore 14, the examination site of the subject 20 placed on the top plate 18 is set at the center of the static magnetic field within the bore 14.

[0028] A multi-channel RF coil (hereinafter referred to as the RF coil), which is composed of a plurality of element coils (hereinafter referred to as elements) for receiving the magnetic resonance signal generated in the subject 20, is fixed to the examination site of the subject 20 by a fixing belt 22. In the example shown in FIG. 1, the abdomen of the subject 20 is the examination site, and the RF coil is attached to the abdomen of the subject 20.

[0029] The RF coil is connected to a receiving-side cable (not shown) that outputs the magnetic resonance signal received by the RF coil. A receiving-side connector (not shown) is connected to the end of this receiving-side cable. The receiving-side connector is connected to the bed-side connector of a bed-side cable (not shown). Thereby, the receiving-side cable and the bed-side cable are communicably connected via their respective connectors.

[0030] The bed-side cable is stored in a cable storage section (not shown) of the bed 16. The magnetic resonance signal of the subject 20 received by the RF coil is transmitted to a signal processing section (not shown) via the receiving-side cable and the bed-side cable. The signal processing section processes the received magnetic resonance signal and converts it into an image signal.

[0031] <Problem 1> FIG. 2 is a schematic cross-sectional view taken along line 2-2 of FIG. 1. As shown in FIG. 2, a back coil (Spine coil) 24 having a plurality of elements (not shown) is disposed on the surface of the top plate 18 on which the subject 20 is placed. Further, an upper abdomen coil 26 fixed by a fixing belt 22 (not shown in FIG. 2) is disposed on the abdomen of the subject 20 placed on the top plate 18. The back coil 24 and the upper abdomen coil 26 correspond to the RF coil.

[0032] It is preferable that the elements of the RF coil are arranged close to the subject 20 without any gaps. However, in the case of a one-piece RF coil with a fixed size such as the upper abdominal coil 26, the variations in the size of the subject 20 cannot be covered, and in the areas that cannot be covered by the elements, the SNR may not be sufficiently obtained. In the example shown in FIG. 2, there are areas on the side surfaces of the subject 20 (the left and right side surfaces of the subject 20 in FIG. 2) that cannot be covered by either the back coil 24 or the upper abdominal coil 26.

[0033] <Problem 2> The procedure for setting the RF coil is cumbersome, and the workflow is degraded. The user first brings an RF coil suitable for the size of the examination target site of the subject 20 from a coil storage area (not shown) to the MRI apparatus 10. Then, the user arranges this RF coil on the examination target site of the subject 20 and fixes it with the fixing belt 22. Also, after the examination, the user needs to remove the fixing belt 22 from the subject 20 and return the RF coil to the coil storage area again.

[0034] 〔First Embodiment〕 〈Configuration of RF Coil〉 FIG. 3 is a perspective view showing an example of an MRI apparatus 10A according to the first embodiment. As shown in FIG. 3, the MRI apparatus 10A includes an RF coil 100 for an MRI apparatus. The RF coil 100 includes a first coil unit 102 and a second coil unit 122.

[0035] The first coil unit 102 includes a first fixing belt 104. One end 104R of the first fixing belt 104 is arranged on the first end 18A side in the X direction of the top plate 18 (an example of the "first end side", the front side of the top plate 18 in FIG. 3), and the other end 104T is a free end.

[0036] The second coil unit 122 includes a second fixing belt 124. One end 124R of the second fixing belt 124 is arranged on the second end 18B side opposite to the first end 18A side in the X direction of the top plate 18 (an example of the "second end side", the back side of the top plate 18 in FIG. 3), and the other end 124T is a free end.

[0037] The first fixed belt 104 and the second fixed belt 124 are each made of a material that is easy to bend. The end 104R of the first fixed belt 104 and the end 124R of the second fixed belt 124 are arranged at the same position on the top plate 18 in the Z direction. The first fixed belt 104 and the second fixed belt 124 are configured to have the same length in the Z direction. Also, the first fixed belt 104 and the second fixed belt 124 are configured to have the same length from the end 104R to the end 104T and from the end 124R to the end 124T. That is, the first fixed belt 104 and the second fixed belt 124 have a similar shape and are arranged symmetrically with respect to the top plate 18.

[0038] The first fixed belt 104 and the second fixed belt 124 may each be arranged on the top plate 18 via a slide mechanism that is movable in the Z direction. Also, the first fixed belt 104 and the second fixed belt 124 may be configured as a single belt fixed to the top plate 18, with both ends being the end 104T and the end 124T.

[0039] FIG. 4 is a perspective view showing an example of the MRI apparatus 10A, and shows a state in which the subject 20 is fixed to the top plate 18 by the RF coil 100. Also, FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 4. When fixing the subject 20 to the top plate 18, first, the user attaches the first fixed belt 104 to the subject 20 from the first end 18A side to the second end 18B side of the top plate 18 on the examination target site (here, the abdomen) of the subject 20 placed on the top plate 18. Next, the user attaches the second fixed belt 124 to the subject 20 by directing it from the second end 18B side to the first end 18A side of the top plate 18 and overlapping at least a part of it with the first fixed belt 104.

[0040] The surfaces of the first fixed belt 104 that contact the second fixed belt 124 and the surfaces of the second fixed belt 124 that contact the first fixed belt 104 are respectively provided with a first surface 106 and a second surface 126 (not shown in FIG. 4) of the hook-and-loop fastener. The hook-and-loop fastener is a coupling member in which a pair of hook surfaces and loop surfaces engage. For example, the first surface 106 is a hook surface and the second surface 126 is a loop surface. The first fixed belt 104 and the second fixed belt 124 are detachably coupled by the first surface 106 and the second surface 126 of the hook-and-loop fastener in the overlapping regions that overlap each other.

[0041] Note that the coupling member that couples the first fixed belt 104 and the second fixed belt 124 is not limited to the hook-and-loop fastener, and a known buckle or the like whose coupling position can be adjusted may be used.

[0042] FIG. 6 is a plan perspective view of the first coil unit 102 and the second coil unit 122.

[0043] F6A in FIG. 6 shows a state in which the first coil unit 102 is placed on the top plate 18 (not shown in FIG. 6). As shown in F6A, a plurality of planar elements 108-1, 108-2, 108-3, 108-4, 108-11, 108-12, 108-13, and 108-14 are arranged on the first fixed belt 104. The shapes of the elements 108-1, 108-2, 108-3, 108-4, 108-11, 108-12, 108-13, and 108-14 are circular in plan view.

[0044] The elements 108-1 to 108-4 form a first outer contour region 110 that is partially overlapped and continuously arranged along the X direction in the plan view of the first fixed belt 104. Here, the element 108-1 and the element 108-2 partially overlap each other, the element 108-2 and the element 108-3 partially overlap each other, and the element 108-3 and the element 108-4 partially overlap each other.

[0045] Similarly, elements 108-11 to 108-14 each partially overlap to form a first outer contour region 112 that is continuously arranged along the X direction.

[0046] Thus, the first coil unit 102 has two rows of first outer contour regions 110 and 112 parallel to the X direction. The first outer contour regions 110 and 112 each have a generally tapered shape as they are spaced apart from the first end 18A of the top plate 18, that is, from the end 104R to the end 104T of the first fixing belt 104.

[0047] Here, the diameters of elements 108-1 to 108-4 decrease from the end 104R to the end 104T of the first fixing belt 104. That is, the diameters of elements 108-1 to 108-4 decrease in the order of 108-1, 108-2, 108-3, 108-4. Also, elements 108-1 to 108-4 are each arranged at positions where the lines connecting their centers are parallel to the X direction.

[0048] Similarly, the diameters of elements 108-11 to 108-14 decrease from the end 104R to the end 104T of the first fixing belt 104. Also, elements 108-11 to 108-14 are each arranged at positions where the lines connecting their centers are parallel to the X direction.

[0049] F6B in FIG. 6 shows a state where the second coil unit 122 is placed on the top plate 18. As shown in F6B, the second coil unit 122 has a plurality of planar elements 128-1, 128-2, 128-3, 128-4, 128-11, 128-12, 128-13, and 128-14 arranged on the second fixing belt 124. The shapes of elements 128-1, 128-2, 128-3, 128-4, 128-11, 128-12, 128-13, and 128-14 are each circular in plan view.

[0050] Elements 128-1 to 128-4 form a second outer contour region 130 that is partially overlapped and continuously arranged along the X direction in the plan view of the second fixed belt 124. Similarly, elements 128-11 to 128-14 form a second outer contour region 132 that is partially overlapped and continuously arranged along the X direction.

[0051] Thus, the second coil unit 122 has two rows of second outer contour regions 130 and 132 parallel to the X direction. The second outer contour regions 130 and 132 each have a tapered shape as they are spaced apart from the second end 18B side of the top plate 18, that is, from the end 124R to the end 124T of the second fixed belt 124.

[0052] Here, elements 128-1 to 128-4 each have a smaller diameter from the end 124R to the end 124T of the second fixed belt 124. That is, the diameters of elements 128-1 to 128-4 are in the order of 128-1, 128-2, 128-3, 128-4 from largest to smallest. Also, elements 128-1 to 128-4 are each arranged at positions where the lines connecting their centers are parallel to the X direction.

[0053] Similarly, elements 128-11 to 128-14 each have a smaller diameter from the end 124R to the end 124T of the second fixed belt 124. Also, elements 128-11 to 128-14 are each arranged at positions where the lines connecting their centers are parallel to the X direction.

[0054] The first outer contour regions 110 and 112 of the first coil unit 102 and the second outer contour regions 130 and 132 of the second coil unit 122 are arranged with a phase shift in the Z direction. Here, the first outer contour regions 110 and 112 of the first coil unit 102 and the second outer contour regions 130 and 132 of the second coil unit 122 are arranged alternately along the Z direction. In the example shown in FIG. 6, from top to bottom in FIG. 6, the first outer contour region 110, the second outer contour region 130, the first outer contour region 112, and the second outer contour region 132 are arranged alternately in this order.

[0055] <Shape of the Outer Perimeter Region> FIG. 7 is a diagram for explaining the shape of the outer perimeter region. Here, the first outer perimeter region 110 formed by elements 108-1 to 108-4 will be described as an example.

[0056] For the first outer perimeter region 110, a trapezoid T1 having a pair of opposite sides parallel to the Z direction is set, which encloses the first outer perimeter region 110 and has the smallest area. When the side on the end 104R side of the first fixed belt 104 is larger than the side on the end 104T side, which is the free end, among the two sides parallel to the Z direction of the trapezoid T1 set for the first outer perimeter region 110, the first outer perimeter region 110 is assumed to have a tapered shape as it moves away from the first end 18A side of the top plate 18, that is, from the end 104R to the end 104T of the first fixed belt 104. Since L1 > L2 for the trapezoid T1 shown in FIG. 7, the first outer perimeter region 110 has a tapered shape.

[0057] Also, in the case of the second outer perimeter region 130, a trapezoid having a pair of opposite sides parallel to the Z direction is set, which encloses the second outer perimeter region 130 and has the smallest area. When the side on the end 124R side of the second fixed belt 124 is larger than the side on the end 124T side, which is the free end, among the two sides parallel to the Z direction of the trapezoid set for the second outer perimeter region 130, the second outer perimeter region 130 is assumed to have a tapered shape as it moves from the end 124R to the end 124T of the second fixed belt 124.

[0058] In the first coil unit 102 and the second coil unit 122 shown in FIG. 6, the first outer perimeter regions 112, and the second outer perimeter regions 130 and 132 each have a smaller side on the free end side and a tapered shape.

[0059] <Size of the Subject and Arrangement of Elements> FIG. 8 is a schematic view showing a state in which the subject 20 is fixed to the top plate 18 by the RF coil 100, and is a cross-sectional view similar to FIG. 5. In FIG. 8, the illustration of the hook-and-loop fastener is omitted. F8A in FIG. 8 shows a case where the subject 20 having a relatively thin body shape (size) is fixed to the top plate 18. Further, F8B in FIG. 8 shows a case where the subject 20 having a relatively thick size is fixed to the top plate 18. As shown in FIG. 8, according to the size of the subject 20, the overlapping length of the first fixing belt 104 and the second fixing belt 124 changes.

[0060] FIG. 9 is a plan perspective view showing the arrangement of elements in a state where the subject 20 is fixed to the top plate 18 by the RF coil 100, and is a view of the state of FIG. 8 seen from the Y-direction side. In FIG. 9, the first fixing belt 104 and the second fixing belt 124 are shown unfolded in the X direction.

[0061] F9A in FIG. 9 shows a case where the subject 20 having a relatively thin size is fixed to the top plate 18. Further, F9B in FIG. 9 shows a case where the subject 20 having a relatively thick size is fixed to the top plate 18. As shown in FIG. 9, in a state where the RF coil 100 is attached to the subject 20, the first outer peripheral regions 110 and 112 arranged in a comb shape on the first fixing belt 104 and the second outer peripheral regions 130 and 132 arranged in a comb shape on the second fixing belt 124 are arranged in a nested manner and opposed to each other in the Z direction without a gap.

[0062] Here, since the position where the first outer peripheral regions 110 and 112 overlap with the second outer peripheral regions 130 and 132 changes according to the size of the subject 20, the coil size in the circumferential direction (X direction in FIG. 9) of the subject 20 changes in a gradation.

[0063] <Effect> According to the RF coil 100, the subject 20 can be fixed to the top plate 18, and the RF coil can be set up and put away only by operating the first fixing belt 104 and the second fixing belt 124, so that the workflow can be improved.

[0064] According to the RF coil 100, even if the overlapping position of the first fixing belt 104 and the second fixing belt 124 changes depending on the size of the subject 20, a gap between elements is less likely to occur. As a result, regardless of the size of the subject 20, the inspection site of the subject 20 can be appropriately covered with the elements.

[0065] FIG. 10 is a comparison diagram for explaining the effect of the first embodiment, and shows an RF coil 100C. The RF coil 100C includes a plurality of elements 108C having a constant diameter, and other configurations are the same as those of the RF coil 100. Similar to FIG. 9, FIG. 10 shows the arrangement of the elements in a state where the subject 20 is fixed to the top plate 18 by the RF coil 100C, with the first fixing belt 104 and the second fixing belt 124 unfolded in the X direction.

[0066] F10A in FIG. 10 shows a case where the subject 20 having a relatively small size is fixed to the top plate 18. Further, F10B in FIG. 10 shows a case where the subject 20 having a relatively large size is fixed to the top plate 18. As shown in F10A, the elements 108C of the RF coil 100C are arranged so that the inspection site of the subject 20 having a relatively small size can be appropriately covered with the elements 108C. However, as shown in F10B, in the case of the subject 20 having a relatively large size, there is a region AR where the inspection site cannot be covered with the elements 108C. In the region AR, the SNR of the magnetic resonance signal decreases, which is not preferable.

[0067] According to the RF coil 100 according to the first embodiment, it is possible to prevent a decrease in SNR in a region not covered by the elements in the case of the subject 20 having a relatively large size, as compared with the RF coil 100C shown in FIG. 10.

[0068] Note that the appropriate range of the size of the subject 20 for which the RF coil 100 is effective is a range in which a relatively large gap cannot be formed between the elements. Therefore, it is preferable to provide a guide display indicating the appropriate range of the overlapping amount of the first fixing belt 104 and the second fixing belt 124 on the first fixing belt 104, so that the user can confirm whether it is within the appropriate range during setting.

[0069] The bidirectional arrows 114A and 114B shown in FIG. 9 are an example of a guide display indicating the appropriate range of the overlapping amount. When the second fixing belt 124 is overlapped on the first fixing belt 104, if the position of the end portion 124T of the second fixing belt 124 is within the range of the bidirectional arrows 114A and 114B, the overlapping amount of the first fixing belt 104 and the second fixing belt 124 is appropriate. The guide display is not limited to the bidirectional arrows 114A and 114B, and any display that allows the user to recognize the appropriate range of the overlapping amount may be used.

[0070] 〔Second Embodiment〕 〈Configuration of RF Coil〉 FIG. 11 is a plan perspective view of the first coil unit 102A and the second coil unit 122A according to the second embodiment.

[0071] F11A in FIG. 11 shows a state where the first coil unit 102A is placed on the top plate 18 (not shown in FIG. 11). As shown in F11A, the first coil unit 102A includes a plurality of elements 108A-1, 108A-2, 108A-3, 108A-4, 108A-11, 108A-12, 108A-13, and 108A-14 two-dimensionally arranged on the first fixing belt 104A.

[0072] The elements 108A-1 to 108A-4 form a first outer contour region 110A that is partially overlapped and continuously arranged along the X direction in a plan view of the first fixing belt 104A. Similarly, the elements 108A-11 to 108A-14 form a first outer contour region 112A that is partially overlapped and continuously arranged along the X direction.

[0073] The diameter of elements 108A-1 to 108A-4 of the first outer peripheral region 110A becomes smaller as it goes from the end 104AR side of the first fixed belt 104 fixed to the first end 18A side of the top plate 18 toward the end 104AT side which is the free end. Similarly, the diameter of elements 108A-11 to 108A-14 of the first outer peripheral region 112A becomes smaller as it goes from the end 104AR side toward the end 104AT side.

[0074] Elements 108A-1 to 108A-4 and elements 108A-11 to 108A-14 are arranged in alignment in FIG. 11. That is, elements 108A-1, 108A-2, 108A-3, 108A-4 are arranged with their ends aligned so as to be in contact with a straight line L1 in one side in the Z direction (the upper side in FIG. 11) of elements 108A-1 to 108A-4 and parallel to the X direction. Further, elements 108A-11, 108A-12, 108A-13, 108A-14 are arranged with their ends aligned so as to be in contact with a straight line L2 in one side in the Z direction (the upper side in FIG. 11) of elements 108A-11 to 108A-14 and parallel to the X direction. Further, a guide line 116 is provided on the first fixed belt 104A. The guide line 116 is provided at a position that bisects the interval between the first outer peripheral regions 110A and 112A.

[0075] F11B in FIG. 11 shows a state in which the second coil unit 122A is placed on the top plate 18. As shown in F11B, the second coil unit 122A includes a plurality of elements 128A-1, 128A-2, 128A-3, 128A-4, 128A-11, 128A-12, 128A-13, and 128A-14 arranged two-dimensionally on the second fixed belt 124A.

[0076] Elements 128A-1 to 128A-4 form a second outer peripheral region 130A in which a part overlaps in a plan view of the second fixed belt 124 and is continuously arranged along the X direction. Similarly, elements 128A-11 to 128A-14 form a second outer peripheral region 132A in which a part overlaps and is continuously arranged along the X direction.

[0077] The second outer region 130A has the diameters of the elements 128A-1 to 128A-4 decreasing from the end 124R side to the end 124T side of the second fixing belt 124 fixed to the second end 18B side of the top plate 18. Similarly, the second outer region 132A has the diameters of the elements 128A-11 to 128A-14 decreasing from the end 124R side to the end 124T side.

[0078] The elements 128A-1 to 128A-4 and the elements 128A-11 to 128A-14 are arranged in alignment in FIG. 11. That is, the elements 128A-1, 128A-2, 128A-3, 128A-4 are arranged with their ends aligned so as to contact a straight line L3 in the other side in the Z direction (the lower side in FIG. 11) of the elements 128A-1 to 128A-4 and parallel to the X direction. Also, the elements 128A-11, 128A-12, 128A-13, 128A-14 are arranged with their ends aligned so as to contact a straight line L4 in the other side in the Z direction (the lower side in FIG. 11) of the elements 128A-11 to 128A-14 and parallel to the X direction.

[0079] The first outer regions 110A and 112A of the first coil unit 102A and the second outer regions 130A and 132A of the second coil unit 122A are arranged alternately along the Z direction of the top plate 18. In the example shown in FIG. 11, they are arranged alternately in the order of the first outer region 110A, the second outer region 130A, the first outer region 112A, and the second outer region 132A from top to bottom in FIG. 11.

[0080] Further, a guide line 136 is provided on the second fixing belt 124A. The guide line 136 is provided at a position passing through the centers of the elements 128A-1, 128A-2, 128A-3, 128A-4 that constitute the second outer region 130A.

[0081] 〈Shape of the outer region〉 FIG. 12 is a diagram for explaining the shape of the outer peripheral region. Here, the first outer peripheral region 110A formed by the elements 108A-1 to 108A-4 will be described as an example.

[0082] For the first outer peripheral region 110A, a trapezoid T2 having a pair of opposite sides parallel to the Z direction is set, which encloses the first outer peripheral region 110A and has the smallest area. As shown in FIG. 12, for the trapezoid T2 set for the first outer peripheral region 110A, among the two sides parallel to the Z direction of the trapezoid T2, the length L3 of the side on the end 104AR side of the first fixed belt 104A is larger than the length L4 of the side on the end 104AT side which is the free end. Therefore, the first outer peripheral region 110A has a tapered shape. Similarly, the first outer peripheral region 112A, the second outer peripheral regions 130A and 132A each have a smaller side on the free end side and a tapered shape.

[0083] 〈Size of the Subject and Arrangement of the Elements〉 FIG. 13 is a plan perspective view showing the arrangement of the elements in a state where the subject 20 is fixed to the top plate 18 by the RF coil 100A including the first coil unit 102A and the second coil unit 122A. In FIG. 13, similar to FIG. 9, the first fixed belt 104A and the second fixed belt 124A are shown unfolded in the X direction.

[0084] F13A in FIG. 13 shows the case where the subject 20 with a relatively small size is fixed to the top plate 18. Further, F13B in FIG. 13 shows the case where the subject 20 with a relatively large size is fixed to the top plate 18. Here, the second fixing belt 124A is overlapped on the first fixing belt 104A so that the guide line 116 and the guide line 136 overlap. That is, the guide lines 116 and 136 are arranged at positions adjacent to each other in a plan view on the other side (the lower side in FIG. 13) of the first outer region 110A and the one side (the upper side in FIG. 13) of the second outer region 130A, and for arranging the other side (the lower side in FIG. 13) of the first outer region 112A and the one side (the upper side in FIG. 13) of the second outer region 132A at positions adjacent to each other in a plan view. In the example shown in F13A, since the guide line 116 and the guide line 136 are overlapped, the first fixing belt 104A and the second fixing belt 124A are overlapped with a shift in the Z - direction position.

[0085] As shown in FIG. 13, as the overlapping position of the first outer regions 110A, 112A and the second outer regions 130A, 132A changes according to the size of the subject 20, the coil size in the X - direction changes in a gradation.

[0086] <Effect> According to the RF coil 100A, in the direction in which the diameter of the element becomes smaller, that is, in the circumferential direction of the subject 20 (the X - direction in FIG. 11), the first fixing belt 104A arranges the elements in an upper - aligned manner, and the second fixing belt 124A arranges the elements in a lower - aligned manner. When the first fixing belt 104 and the second fixing belt 124 are overlapped, the distribution of the elements does not become oblique with respect to the X - direction.

[0087] In the RF coil 100A, the direction of change in the overlapping state of the first fixing belt 104 and the second fixing belt 124 according to the size of the subject 20 is the element arrangement direction, which is an oblique direction with respect to the X direction. According to the RF coil 100A, by displaying the guide lines 116 and 136 on the first fixing belt 104 and the second fixing belt 124 so that the user can recognize the element arrangement direction, even when the size of the subject 20 is different, the user overlaps the second fixing belt 124A on the first fixing belt 104A so that the guide line 116 and the guide line 136 coincide, whereby the first outer contour regions 110A, 112A and the second outer contour regions 130A, 132A can be appropriately arranged with respect to the subject 20.

[0088] Note that the display for enabling the user to recognize the element arrangement direction is not limited to the guide lines, and any display that allows the user to overlap the first fixing belt 104 and the second fixing belt 124 so as to appropriately arrange the first outer contour regions 110A, 112A and the second outer contour regions 130A, 132A is acceptable.

[0089] 〔Third Embodiment〕 〈Configuration of RF Coil〉 FIG. 14 is a plan perspective view of the first coil unit 102B and the second coil unit 122B according to the third embodiment.

[0090] F14A in FIG. 14 shows a state in which the first coil unit 102B is placed on the top plate 18 (not shown in FIG. 14). As shown in F14A, the first coil unit 102B includes a plurality of elements 108B-1 and 108B-2 two-dimensionally arranged on the first fixing belt 104B.

[0091] The plurality of elements 108B-1 each have a constant diameter. Also, the plurality of elements 108B-1 each form a first outer contour region 110B that is partially overlapped and continuously arranged along the X direction in a plan view of the first fixed belt 104B. Similarly, the plurality of elements 108B-2 each have a constant diameter, and each form a first outer contour region 112B that is partially overlapped and continuously arranged along the X direction.

[0092] In the first outer contour region 110B, the number of elements 108B-1 per unit area decreases from the end 104BR side fixed to the top plate 18 of the first fixed belt 104B toward the end 104BT side which is the free end. Similarly, in the first outer contour region 112B, the number of elements 108B-2 per unit area decreases from the end 124BR side toward the end 124BT side.

[0093] F14B in FIG. 14 shows a state where the second coil unit 122B is placed on the top plate 18. As shown in F14B, the second coil unit 122B includes a plurality of elements 128B-1 and 128B-2 two-dimensionally arranged on the second fixed belt 124B.

[0094] The plurality of elements 128B-1 each have a constant diameter. Also, the plurality of elements 128B-1 each form a second outer contour region 130B that is partially overlapped and continuously arranged along the X direction in a plan view of the second fixed belt 124B. Similarly, the plurality of elements 128B-2 each have a constant diameter, and each form a second outer contour region 132B that is partially overlapped and continuously arranged along the X direction.

[0095] In the second outer contour region 130B, the number of elements 128B-1 per unit area decreases from the end 124BR side of the second fixed belt 124B toward the end 124BT side. Similarly, in the second outer contour region 132B, the number of elements 128B-2 per unit area decreases from the end 124BR side toward the end 124BT side.

[0096] The first outer peripheral regions 110B and 112B of the first coil unit 102B and the second outer peripheral regions 130B and 132B of the second coil unit 122B are alternately arranged along the Z direction of the top plate 18. In the example shown in FIG. 14, from top to bottom in FIG. 14, the first outer peripheral region 110B, the second outer peripheral region 130B, the first outer peripheral region 112B, and the second outer peripheral region 132B are alternately arranged in this order.

[0097] 〈Shape of the outer peripheral region〉 FIG. 15 is a diagram for explaining the shape of the outer peripheral region. Here, the first outer peripheral region 110B formed by a plurality of elements 108B-1 will be described as an example.

[0098] Regarding the first outer peripheral region 110B, a trapezoid T3 having a pair of opposite sides parallel to the Z direction is set, which encloses the first outer peripheral region 110B and has the smallest area. As shown in FIG. 15, for the trapezoid T3 set for the first outer peripheral region 110B, among the two sides parallel to the Z direction of the trapezoid T3, the length L5 of the side on the end 104BR side of the first fixing belt 104B is larger than the length L6 of the side on the end 104BT side which is the free end. Therefore, the first outer peripheral region 110B has a tapered shape. Similarly, the first outer peripheral region 112B, the second outer peripheral regions 130B and 132B each have a smaller side on the free end side and a tapered shape.

[0099] 〈Size of the subject and arrangement of the elements〉 FIG. 16 is a plan perspective view showing the arrangement of elements in a state where the subject 20 is fixed to the top plate 18 by the RF coil 100B including the first coil unit 102B and the second coil unit 122B. In FIG. 16, similar to FIG. 9, the first fixing belt 104B and the second fixing belt 124B are shown unfolded in the X direction.

[0100] F16A in FIG. 16 shows the case where the subject 20 with a relatively small size is fixed to the top plate 18. Also, F16B in FIG. 16 shows the case where the subject 20 with a relatively large size is fixed to the top plate 18.

[0101] As shown in FIG. 16, since the positions where the first outer contour regions 110B and 112B and the second outer contour regions 130B and 132B overlap change according to the size of the subject 20, the coil size in the X direction changes in a gradient.

[0102] <Effect> According to the RF coil 100B, even if the diameter of the element is constant, by arranging the elements in a tapered region similar to the first outer contour regions 110 and 112 and the second outer contour regions 130 and 132 of the first embodiment, the same effects as those of the first embodiment can be obtained. Further, according to the RF coil 100B, since the diameter of the element is constant, the management cost can be reduced by the common use of parts.

[0103] Here, the case where the number of rows in the coil region is the same in the first coil unit 102B and the second coil unit 122B has been described. However, in the RF coil 100B, the first coil region of the first coil unit 102B may have two rows, while the second coil region of the second coil unit 122B may have one row or three rows. Thereby, an optimal sensitivity region can be obtained for the target site. The same applies to the RF coil 100 according to the first embodiment and the RF coil 100A according to the second embodiment.

[0104] [Others] The technical scope of the present invention is not limited to the scope described in the above embodiments. The configurations and the like in each embodiment can be appropriately combined between the embodiments without departing from the gist of the present invention.

Explanation of Reference Numerals

[0105] 10... MRI apparatus 12... Gantry 14... Bore 16... Bed 18... Ceiling 20... Subject 22... Fixing belt 100, 100A, 100B, 100C... RF coil 102, 102A, 102B... First coil unit 122, 122A, 122B… second coil unit

Claims

1. An RF (Radio Frequency) coil for a magnetic resonance imaging apparatus including a top plate on which a subject is placed along a longitudinal direction, a first fixing belt disposed on the top plate and attached to the subject from a first end side in a width direction orthogonal to the longitudinal direction of the top plate toward a second end side opposite to the first end side, a plurality of elements disposed on the first fixing belt, a first coil unit including the above, a second fixing belt disposed on the top plate and attached to the subject with at least a part thereof overlapping the first fixing belt from the second end side of the top plate toward the first end side, a plurality of elements disposed on the second fixing belt, a second coil unit including the above, and comprising, a first outer contour region formed by the plurality of elements of the first coil unit has a tapered shape as it is spaced apart from the first end side of the top plate, a second outer contour region formed by the plurality of elements of the second coil unit has a tapered shape as it is spaced apart from the second end side of the top plate, the first outer contour region and the second outer contour region are arranged with a phase shift in the longitudinal direction, an RF coil.

2. the plurality of elements of the first coil unit form a plurality of the first outer contour regions, the plurality of elements of the second coil unit form a plurality of the second outer contour regions, the plurality of the first outer contour regions and the plurality of the second outer contour regions are alternately arranged along the longitudinal direction, the RF coil according to Claim 1.

3. each of the plurality of elements has a diameter that decreases as it is spaced apart from the top plate, the RF coil according to Claim 1.

4. the plurality of elements are arranged at positions where a line connecting the centers is parallel to the width direction, the RF coil according to Claim 3.

5. the plurality of elements of the first coil unit are arranged with their ends aligned on one side in the longitudinal direction, the plurality of elements of the second coil unit are arranged with their ends aligned on the other side in the longitudinal direction, the RF coil according to Claim 3.

6. The first fixed belt and the second fixed belt are provided with guide lines for arranging the other side of the first outer contour region and the one side of the second outer contour region adjacent to each other in a plan view when the first fixed belt and the second fixed belt are attached to the subject. The RF coil according to claim 5.

7. Each of the plurality of elements has a constant diameter and is arranged such that the number per unit area decreases as the distance from the top plate increases. The RF coil according to claim 1.

8. The first fixed belt is provided with a guide display indicating an appropriate range of a position where the second fixed belt overlaps. The RF coil according to claim 1.

9. The first fixed belt and the second fixed belt are provided with the first surface and the second surface of a pair of surface fasteners whose first surface and second surface engage with each other at a position where they come into contact with each other when attached to the subject. The RF coil according to claim 1.

10. A top plate on which a subject is placed; The RF coil according to any one of claims 1 to 9; A bed apparatus comprising:

11. The bed apparatus according to claim 10; A gantry including a magnetic field generation source and having an opening; A drive mechanism for moving the top plate in the longitudinal direction and entering and exiting the opening of the gantry; A magnetic resonance imaging apparatus comprising:

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