High-frequency coil device and magnetic resonance imaging device using the same

Abstract

To provide a high-frequency coil device that can maintain a distance between coils at any attachment position and achieve uniform sensitivity distribution and high sensitivity in an RF coil including a movable coil unit.SOLUTION: A high-frequency coil device includes: first coil unit that can move on a substantially-circular trajectory; and a second coil unit that is fixed in the substantially-circular trajectory. The first coil unit and the second coil unit are arranged at substantially-point symmetrical positions. Magnetic coupling of conductor loops contained in both coil units is kept almost constant in the movable range of the first coil unit.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a radio frequency coil device used as an RF coil of a magnetic resonance imaging (MRI) apparatus. Background Art

[0002] In an MRI apparatus, a radio frequency magnetic field is applied to a subject placed in a static magnetic field space, nuclear magnetic resonance signals generated from the subject are collected, and an image of the subject is generated. A radio frequency coil (RF coil) used for applying the radio frequency magnetic field and receiving the nuclear magnetic resonance signal is required to have high and uniform sensitivity to obtain good images. In particular, a receiving RF coil can improve receiving sensitivity by being closely attached to the subject.

[0003] In MRI apparatuses, in order to achieve adhesion to a subject and high sensitivity, multi-array coils formed by combining a plurality of small coils into a single coil device are widely used. In such a multi-array coil, in order to obtain high sensitivity and suppress electromagnetic interference between coils, the coil is regularly designed such that portions of elements (conductor loops) constituting individual coils overlap each other (for example, Patent Document 1).

[0004] However, since the size and shape of the subject to which the coil is attached vary depending on the subject, it is difficult to maintain a regular arrangement when attempting to bring the coil into close contact with the subject. Although circuit structures that suppress electromagnetic interference have been developed, interference is not completely eliminated, so maintaining a regular arrangement with overlapping portions of elements (conductor loops) remains important for ensuring high sensitivity.

[0005] On the other hand, for RF coils that are difficult to closely adhere to a subject, such as coils for the head, there has also been proposed a coil device in which a plurality of coil units with elements regularly arranged are combined, the coil units are configured to be movable, and are attached to the subject (Patent Document 2, Patent Document 3). Prior Art Documents [Patent Documents]

[0006] [Patent Document 1] International release 2018 / 098255 [Patent Document 2] Specification of Patent No. 6195731 [Patent Document 3] Japanese Patent Publication No. 2021-137388 [Disclosure of the Invention] [Problems that the invention aims to solve]

[0007] In coil devices with movable coil units, while the regular arrangement of elements can be maintained for individual coil units, the relative positions of the coil units change because one of them is movable. At the mounting position, the relative positions of the loops constituting one coil unit and the loops constituting another coil unit change depending on the size and mounting method of the subject being mounted. Despite the elements being arranged to suppress electromagnetic interference, this can cause electromagnetic interference and lead to a decrease in sensitivity.

[0008] For example, the RF coil for the head disclosed in Patent Document 3 has a movable mask-shaped coil unit that covers the top of the patient's head and part of their face, and is configured so that the mask-shaped coil unit can be closely fitted to the face depending on the size of the subject. However, the positional relationship with the fixed coil placed at the back of the head differs depending on whether the head size is large or small, making it difficult to maintain a positional relationship that suppresses electromagnetic interference.

[0009] The present invention aims to provide a high-frequency coil device that includes a movable coil unit as described above, which can maintain the distance between coils at any mounting position, and can achieve a uniform sensitivity distribution and high sensitivity. [Means for solving the problem]

[0010] The present invention relates to a high-frequency coil device having multiple coil units whose relative positions are variable, which enables attachment to a subject while maintaining the relative positions of the coils by devising the trajectory of the movable coils.

[0011] That is, one embodiment of the high-frequency coil device of the present invention is a high-frequency coil device for magnetic resonance imaging comprising a first coil unit having at least one conductor loop and a second coil unit having at least one conductor loop, wherein the relative positions of the first coil unit and the second coil unit are variable, and within at least a portion of the range of motion, the conductor loop of the first coil unit and the conductor loop of the adjacent second coil unit move while maintaining electromagnetic coupling.

[0012] Another embodiment of the high-frequency coil device of the present invention comprises a first coil unit movable on a circular track and a second coil unit fixed within the circular track, characterized in that the first coil unit and the second coil unit are arranged in substantially point-symmetric positions.

[0013] Furthermore, the MRI apparatus of the present invention is equipped with a high-frequency coil of each of the above embodiments as at least one of the RF receiving coil and RF transmitting coil. [Effects of the Invention]

[0014] According to the present invention, a movable RF coil moves along a predetermined trajectory relative to a fixed RF coil, and during this movement, the relationship between the two coils, the distance between the coils that maintains the magnetic coupling between them, or the overlap area is maintained. This suppresses fluctuations in electromagnetic interference and enables the achievement of a uniform sensitivity distribution. Furthermore, because at least one of the coil units is movable, the contact with the subject can be improved, and high sensitivity can be achieved. [Brief explanation of the drawing]

[0015] [Figure 1] A figure showing one embodiment of the high-frequency coil device of the present invention. [Figure 2] A diagram showing the positional relationship between two conductor loops at each position in the movable range of a movable coil unit. [Figure 3] A diagram showing an embodiment of the shape of a conductor loop. [Figure 4] A diagram showing an example of a trajectory along which a movable coil unit moves. [Figure 5] A diagram showing the positional relationship of conductor loops at each position in the movable range when a deformed rectangular conductor loop is used. [Figure 6] A diagram showing an embodiment including a movable portion of the high-frequency coil device of the present invention. [Figure 7] A diagram showing Embodiment 1 of the movable portion. [Figure 8] A diagram explaining the movement of the high-frequency coil in the embodiment of Fig. 6. [Figure 9] A diagram showing Embodiment 2 of the movable portion. [Figure 10] A diagram showing an outline of an MRI apparatus to which the present invention is applied. [Figure 11] A diagram showing an example of an RF coil (high-frequency coil device) of the MRI apparatus in Fig. 10. MODE FOR CARRYING OUT THE INVENTION

[0016] Hereinafter, embodiments of the high-frequency coil device of the present invention will be described with reference to the drawings. In the following description, as an example, the case where the high-frequency coil device functions as a receiving coil for an MRI apparatus will be described.

[0017] As shown in Fig. 1, the high-frequency coil device 1 of the present embodiment has a basic structure including one RF coil unit 10, an RF coil unit 20 whose position relative to the RF coil unit 10 changes, and a mechanism section 30 for moving the RF coil unit 20 relative to the RF coil unit 10. The movement of the RF coil unit 20 relative to the RF coil unit 10 is a relative movement where one is movable when the other is fixed, and includes, for example, the case where both are movable. Here, to simplify the description, the RF coil unit 10 is assumed to be fixed, and the RF coil unit 20 is assumed to be movable.

[0018] The high-frequency coil device 1 of this embodiment has a structure that changes the relative positions of multiple coil units, thereby facilitating the attachment process to the inspection target (various parts of the human body) and maintaining a tight seal during attachment.

[0019] The RF coil unit 10 and the movable RF coil unit 20 each include at least one conductor loop 11, 12. Each conductor loop 11, 12 is tuned to receive the nuclear magnetic resonance signal from the MRI device. This tuning is performed by the conductor loop itself (conductor) and capacitors added to the conductor loop. The RF coil unit 10 and the movable RF unit 20 may also be multi-array coils in which multiple conductor loops are connected in a predetermined arrangement. In this case, each of the multiple conductor loops is tuned to receive the nuclear magnetic resonance signal, and the overlap between each conductor is arranged to minimize electromagnetic interference.

[0020] The mechanism 30 includes, for example, a fixing part 31 to which the RF coil unit 10 is fixed, and a movable part 33 fixed to the fixing part 31 that moves the RF coil unit 20 along a predetermined trajectory. When the high-frequency coil device 1 of this embodiment is attached to an inspection area 40 such as the head of a subject, for example, with the inspection area placed on the RF coil unit 10 fixed to the fixing part 31, the RF coil unit 20 is moved along a predetermined trajectory, and the RF coil unit 10 and RF coil unit 20 are attached so as to cover the inspection area 40.

[0021] In a conventional movable high-frequency coil, for example, in which the movable coil is attached by contacting it from both sides or the top of the subject's head, the position of the movable coil located on the back of the head changes in the direction of distance, and when the movable coil is in close contact with the head, the distance between the two changes depending on the size of the subject. In other words, in subjects with large heads, the fixed coil and the movable coil are relatively far apart, while in subjects with small heads, the fixed coil and the movable coil are closer together, and the electromagnetic coupling changes at each position. That is, even if adjustments are made to suppress electromagnetic coupling for each coil, the balance of the electromagnetic coupling adjustment of all conductor loops is disrupted when it is used as a high-frequency coil device.

[0022] In this embodiment, the high-frequency coil device 1 is provided with a movable part 33 that moves the movable RF coil unit 20 relative to the RF coil unit 10 such that the movement trajectory of the conductor loop (second conductor loop) 21, which is adjacent to the conductor loop (first conductor loop) 11 of the RF coil unit 10, maintains approximately the same overlap area as the first conductor loop 11, thereby maintaining the electromagnetic coupling of both coil units 10 and 20 within an adjusted range.

[0023] Specifically, as shown in Figure 2, the trajectory 330 of the movable RF coil unit 20 is generally circular, and its center C lies within the region where the second conductor loop 21 of the RF coil unit 20 and the first conductor loop 11 of the RF coil unit 10 overlap. As a result, when the RF coil unit 20 moves from (a) to (c) in Figure 2, the positional relationship between the second conductor loop 21 and the first conductor loop 11, specifically the distance between the center of the second conductor loop and the center of the first conductor loop 11, remains almost constant, and the overlapping area of ​​the two conductor loops that affect electromagnetic coupling remains almost constant.

[0024] In the example shown in Figure 2, the movable RF coil unit 20 maintains a constant overlap area of ​​both conductor loops from position (a) to position (c), which is 90 degrees. However, the range in which the overlap area is kept constant does not need to be the entire range of motion of the movable RF coil unit; it only needs to be a position close to the object being examined. For example, a circular trajectory should be maintained in a range of about 15 to 20 degrees, such as the range in which adjustments can be made between large and small patients, or between the fixed position for a patient with claustrophobia and the fixed position for a normal patient. In other words, a portion of the trajectory within the range of motion may include linear trajectories that move the movable RF coil unit in a straight line, such as horizontally, vertically, or diagonally.

[0025] The conductor loops 11 and 21 can take on various shapes, as shown in Figures 3(a) to 3(d), and any desired sensitivity can be achieved by using any shape. Furthermore, as shown in Figure 3(c), by making a part of the rectangle into an arc shape, as shown in Figure 5, it becomes easy to control the area of ​​the overlapping portion of the two conductor loops 11 and 21, and changes in the overlapping area due to the movement of the RF coil unit 20 can be kept to a minimum.

[0026] Figure 3(d) shows an example of a figure-eight loop that includes a section where the conductor loops cross. Adopting such a conductor loop makes it easier to obtain depth sensitivity. Furthermore, by making the overlapping section of the figure-eight loop arc-shaped, the same effect as the coil shape in (c) can be obtained.

[0027] Furthermore, the trajectory of the movable RF coil unit that maintains the positional relationship between the second conductor loop 21 and the first conductor loop 11 is not limited to a circular trajectory, but can be appropriately changed according to the shape of the conductor loops, as long as it minimizes the change in the overlapping area of ​​the conductor loops. Figure 4 shows examples of elliptical and polygonal trajectories 330' and 330'' when one of the conductor loops is rectangular. In the case of an elliptical trajectory, there are two trajectory centers, so the trajectory of the second conductor loop 21 is determined so that the center of one of them lies in the region where the two conductor loops overlap. Note that the example in Figure 4 shows the case where the conductor loop 11 of the fixed RF coil unit 10 is rectangular, but conversely, the conductor loop 21 of the movable RF coil unit 20 may also be rectangular.

[0028] According to this embodiment, by configuring the movable part 33 so that the movable RF coil unit 20 moves along the fixed RF coil unit 10, it is possible to always attach the device in a secure and operable manner, even to subjects of varying sizes and attachment positions, while maintaining uniformity of sensitivity.

[0029] <Embodiment 1> The basic structure and movement of the high-frequency coil device of this embodiment have been described above. Below, a specific embodiment of the structure of the high-frequency coil device will be described. In this embodiment, the structure of the head coil disclosed in Patent Document 3 is used as the basis, and a specific mechanism for realizing the trajectory of the movable RF coil, which is a feature of the present invention, will be described.

[0030] First, the structure of the head coil described above will be explained with reference to Figure 6. This head coil 1A includes a plate-shaped fixing part 31, an RF coil unit 10 fixed to the fixing part 31, an RF coil unit 20 movable relative to the fixed RF coil 10, and a movable part 33 with one end fixed to the fixing part 31 and the movable coil 20 attached to the other end. The RF coil unit 10 and the RF coil unit 20 are each multi-array coils in which a plurality of conductor loops are arranged in a predetermined configuration. Each conductor loop is adjusted with a capacitor (not shown) or the like to receive nuclear magnetic resonance signals, and the overlap between the conductor loops is also adjusted. Furthermore, the conductor loops and adjustment elements such as capacitors that constitute these coil units are fixed in a predetermined configuration to a flexible member such as an insulating resin molded into a predetermined shape. Hereinafter, including the conductors and the entire member that fixes them, the RF coil unit 10 will be referred to as the fixed coil, and the RF coil unit will be referred to as the movable coil.

[0031] In Figure 6, the conductor loops of the movable coil 20 are shown with solid lines, and the conductor loops of the fixed coil 10 are shown with dotted lines. Among these conductor loops, the conductor loops of the movable coil 20 and the conductor loops of the fixed coil 10 that are adjacent to each other are shown with thick lines. In Figure 6, the movable coil 20 and the fixed coil 10 are each shown with two conductor loops, but for example, three or more conductor loops may be arranged to cover the head and maintain appropriate magnetic coupling with each other.

[0032] The fixed coil 10 adheres closely to the back of the head when the head is placed on it. The movable coil 20 has a conductor loop fixed in a predetermined position to a flexible member such as an insulating resin molded into a mask shape, and is worn so as to cover at least part of the face from the top of the head.

[0033] The movable part 33 includes a rail 331 that provides a predetermined track, a slider 332 that fixes the movable coil 20 and moves along the rail 331, and a support part 333 that fixes the rail 331 to the fixed part 31.

[0034] In the illustrated embodiment, the rail 331 has an overall arc shape, and the slider 332 moves along the arc-shaped rail 331, allowing the movable coil 20 to move along a track determined by the shape of the rail.

[0035] Although not shown in the diagram, a locking mechanism may be provided between the rail 331 and the slider 332 to fix the slider to the rail 331 at any desired position. For example, a spring member that connects the slider 332 and the rail 331 in stages can be used as the locking mechanism. A latch or ratchet may also be used.

[0036] With this configuration, as shown in Figure 7, the movable coil 20 can be moved along the rail 331, moving from a position where the movable coil 20 is retracted from the top surface of the fixed coil 10 (retracted position) to a position where it overlaps the top surface ((b) mounting position). Figure 8 shows the change in the relative positions of the conductor loops 21 and 11 from the mounting position until the movable coil 20 is tilted towards the rear of the RF coil unit 10 (0 degrees to 20 degrees). In Figure 8, the conductor loops 21 and 11 that are closest to each other are shown with thick lines, and the other conductor loops are shown with thin lines. As can be seen from Figure 8, the overlapping portion of the two conductor loops 21 and 11 remains almost unchanged between 0 degrees and 20 degrees.

[0037] According to the high-frequency coil device 1A of this embodiment, the movable coil 20 is configured to move along a rail 331 that provides a circular track, thereby maintaining a nearly constant overlap area between the conductor loop 21 constituting the movable coil 20 and the conductor loop 11 of the nearest fixed coil 10. As a result, within the range where the overlap area is maintained, the relationship between the conductor loops, which is initially set to minimize electromagnetic interference, can be maintained regardless of the mounting position in which the movable coil 20 is fixed, thereby achieving high and uniform sensitivity.

[0038] Although Figure 6 shows a combination of rail 331 and slider 332 as the movable part 33, any member that guides the movement of the movable coil 20 along a predetermined trajectory can be used as a means of providing a trajectory for the movable coil, not limited to a combination of rail and slider, but also including grooved rails and hooks that engage with the grooves.

[0039] In this embodiment, the positional relationship between the second conductor loop 21 and the first conductor loop 11, specifically the distance between the center of the second conductor loop and the center of the first conductor loop 11, is kept approximately constant, and the overlapping area of ​​the two conductor loops that affect electromagnetic coupling is kept approximately constant. However, the embodiment is not limited to this. For example, the two conductor loops do not need to overlap. As long as the distance between the two conductor loops is kept approximately constant and the magnetic coupling value is maintained, the sensitivity of the high-frequency coil device can be maintained.

[0040] <Embodiment 2> Figure 9 shows a high-frequency coil device 1B of Embodiment 2, which has a different structure of the movable part 33. As shown in Figure 9, the movable part 33 of Embodiment 2 consists of an arm part 335 that fixes the movable coil 20 and a support part 336 that rotatably supports the arm 335. The arm part 335 is a member that extends from the center C1 of the movable coil 20 material toward both sides along the curved surface of the movable coil 20, and its side ends are supported by support parts 336 provided at two locations corresponding to the left and right sides of the subject.

[0041] In this configuration, the arm portion 335 moves in a circular shape with a radius determined by the distance between the end fixed to the support portion 336 and the central portion where the mask-shaped coil 20 is fixed. This allows the mask-shaped coil 20, fixed to the center of the arm portion 335, to move along a circular trajectory. As a result, similar to the high-frequency coil device 1A shown in Figure 6, the relationship of the conductor loop, which is initially set to minimize electromagnetic interference, can be maintained regardless of the mounting position in which the RF coil unit 20 is fixed.

[0042] Also in this embodiment, means for locking the arm portion 335 at any position (e.g., a latch, a ratchet, a fastening bolt, etc.) can be provided between the arm portion 335 and the support portion 336 to which the arm portion 335 is fixed, whereby the RF coil unit can be installed at a stable mounting position.

[0043] The embodiments of the high-frequency coil device of the present invention have been described above. However, the high-frequency coil device of the present invention is not limited to the embodiments shown in the drawings, and the configuration, shape, combination, arrangement and the like of the conductor loops can be changed. In addition, although the above embodiment describes a high-frequency coil device provided with two coil units, a third RF coil unit as disclosed in Patent Document 3 and the like, for example, a pair of RF coil units installed on the side surface of a subject, can also be added.

[0044] In addition, although the above embodiment mainly describes the case where the present invention is applied to a head coil, the present invention is not limited to use for the head, and is applicable to any high-frequency coil device configured such that at least one of two or more coil units is movable and the position of the coil unit is variable for mounting, and modifications can be made according to the mounting site.

[0045] <Embodiment of MRI Apparatus> The MRI apparatus of the present invention includes the high-frequency coil device of the present invention in at least one of an RF receiving coil and an RF transmitting coil. Since configurations other than the high-frequency coil device are the same as those of a general MRI apparatus, detailed description thereof is omitted, and only an outline of the apparatus is described here.

[0046] Figure 10 is a block diagram showing the schematic configuration of the MRI apparatus 100. As shown in this figure, the MRI apparatus 100 includes a horizontal magnetic field magnet 110, a gradient magnetic field coil 131, an RF transmitting coil 151, an RF receiving coil 161, a gradient magnetic field power supply 132, a shim coil 121, a shim power supply 122, a high-frequency magnetic field generator 152, a receiver 162, a magnetic coupling prevention circuit drive device 180, a computer (PC) 170, a sequencer 140, and a display device 171. The subject 40 is placed on the table 102 and positioned in the static magnetic field space formed by the magnet 110.

[0047] The gradient coil 131 is connected to the gradient power supply 132 and generates a gradient magnetic field. The shim coil 121 is connected to the shim power supply 122 and adjusts the uniformity of the magnetic field. The RF transmitting coil 151 is connected to the high-frequency magnetic field generator 152 and irradiates (transmits) a high-frequency magnetic field to the subject 103. The RF receiving coil 161 is connected to the receiver 162 and receives the nuclear magnetic resonance signal from the subject 103. The magnetic coupling prevention circuit drive device 180 is connected to the magnetic coupling prevention circuit. The magnetic coupling prevention circuit is a circuit connected to the RF transmitting coil 151 and the RF receiving coil 161, respectively, that prevents magnetic coupling between the RF transmitting coil 151 and the RF receiving coil 161.

[0048] The sequencer 140 sends commands to the gradient magnetic field power supply 132, the high-frequency magnetic field generator 152, and the magnetic coupling prevention circuit drive device 180, causing them to operate. The commands are sent according to instructions from the computer (PC) 170. Also, according to instructions from the computer (PC) 170, the receiver 162 sets the magnetic resonance frequency to be used as the detection reference. For example, according to a command from the sequencer 140, a high-frequency magnetic field is irradiated onto the subject 103 through the RF transmitting coil 151. The nuclear magnetic resonance signal generated from the subject 103 by the irradiation of the high-frequency magnetic field is detected by the RF receiving coil 161 and detected by the receiver 162.

[0049] The computer (PC) 170 also functions as a signal processing unit that controls the operation of the entire MRI apparatus 100 and performs various signal processing. For example, it receives the signal detected by the receiver 162 via the A / D conversion circuit and performs signal processing such as image reconstruction. The results are displayed on the display device 171. The detected signal and measurement conditions are stored in the storage medium 132 as needed. It also sends commands to the sequencer 140 so that each device operates at a pre-programmed timing and intensity. Furthermore, when it is necessary to adjust the static magnetic field uniformity, the sequencer 140 sends a command to the shim power supply 122, causing the shim coil 121 to adjust the magnetic field uniformity.

[0050] Next, Figure 11 shows an example of the configuration of the RF transmitting coil 151 and RF receiving coil 161 of this embodiment. In Figure 11, as an example, an RF coil having a birdcage shape (birdcage RF coil) 151A is used as the RF transmitting coil 151, and an array coil 161A, which consists of multiple loop-shaped RF coils (surface coils) arranged in a row, is used as the RF receiving coil 161. In Figure 11, two surface coils (sub-coils) that make up the array coil 161A are shown, but the number of sub-coils may be three or more, or it may be just one.

[0051] The resonant frequency of the birdcage-type RF coil 151A, used as the RF transmitting coil 151, is adjusted to the resonance frequency of the element to be excited, for example, the magnetic resonance frequency of hydrogen nuclei that can excite hydrogen nuclei. The array coil 161A, used as the RF receiving coil 161, is adjusted to detect the nuclear magnetic resonance signal of the element that the birdcage-type RF coil 151A can excite.

[0052] The MRI apparatus of this embodiment includes, as the RF receiving coil 161, a high-frequency coil device for the head, 1A, 1B as shown in Figure 1 or Figure 6, i.e., an RF coil unit (fixed coil) 10 fixed to a fixed part 31, and a movable RF coil unit (movable coil) 20 supported by a movable part 33 and capable of changing position relative to the RF coil unit 10.

[0053] When attaching the high-frequency coil device 1 to a subject, the high-frequency coil device 1 is placed on a table 102 inserted into the examination space of the MRI machine, and the subject's head is placed on the fixed coil 10 with the movable coil 20 in a retracted position away from the fixed coil 10 (Figure 7(a)). Next, the movable coil 20 is moved from the retracted position along the subject's head (Figure 7(b)) and fixed to the subject in a position appropriate to the purpose of the examination. Fixation may be performed using a belt (not shown) provided on the fixing part 31, or, if the movable part 33 is provided with a means for locking the slider (or engaging with a groove) to which the movable coil 20 is fixed, the movable coil 20 may be fixed in a predetermined position using the locking means.

[0054] The locking mechanism allows the slider to be fixed in any position, thereby mounting the movable coil unit 20 in a desired position according to the size of the subject, or in an appropriate position depending on whether or not the subject has claustrophobia.

[0055] Subsequently, the table 102 is moved into the static magnetic field space formed by the magnet 110, and the examination is performed in the same manner as with a normal MRI device. The magnetic resonance signals generated by the subject are received by the coil units 10 and 20 of the high-frequency coil device 1 attached to the subject. In this case, even if the position of the movable coil 20 changes within a predetermined range relative to the fixed coil 10, the conductor loop 21 of the movable coil 20 and the conductor loop 11 of the fixed coil 10 can maintain almost the same overlapping area. Therefore, there is no decrease in sensitivity due to changes in electromagnetic interference, and the uniformity of the sensitivity distribution is maintained. As a result, good images can be obtained.

[0056] In the embodiment shown in Figure 11, the case in which the high-frequency coil device of the present invention is used as the RF receiving coil 161 was described. However, regardless of the presence or absence of the RF transmitting coil 151, the high-frequency coil device used as the RF receiving coil 161 can also be used for transmission, in which case uniform and high irradiation sensitivity can be achieved. [Explanation of Symbols]

[0057] 1,1A,1B: High-frequency coil device, 10: Coil unit (fixed coil), 20: Coil unit (movable coil), 11,12: Conductor loop, 30: Mechanism, 31: Fixed part, 33: Movable part, 331: Rail, 332: Slider, 335: Arm, 336: Fixing member, 100: MRI device, 151: RF transmitting coil, 161: RF receiving coil

Claims

1. A high-frequency coil device for magnetic resonance imaging, comprising a first coil unit having a plurality of conductor loops and a second coil unit having a plurality of conductor loops, The plurality of conductor loops of the first coil unit and the plurality of conductor loops of the second coil unit are each fixed in a predetermined arrangement within the coil unit. A high-frequency coil device characterized in that the first coil unit and the second coil unit have variable relative positions, and within at least a portion of their range of motion, one conductor loop of the first coil unit and the adjacent conductor loop of the second coil unit maintain an electromagnetic coupling while moving.

2. A high-frequency coil device according to claim 1, A high-frequency coil device characterized in that the conductor loop of the first coil unit and the conductor loop of the second coil unit adjacent thereto are arranged in such a positional relationship that the distance between the centers of each conductor loop is substantially constant in at least a portion of the movable range of the second coil unit.

3. A high-frequency coil device according to claim 1, The device further comprises a fixing part for fixing the first coil unit and a movable part for changing the position of the second coil unit relative to the first coil unit. The aforementioned movable part is characterized by moving the second coil unit along a trajectory that maintains electromagnetic coupling.

4. A high-frequency coil device according to claim 3, The aforementioned trajectory is a high-frequency coil device, which is one of a circular trajectory, an elliptical trajectory, or a polygonal trajectory.

5. A high-frequency coil device according to claim 3, A high-frequency coil device characterized in that the overlapping area of ​​a portion of the conductor loops of the first coil unit and the second coil unit remains constant and is movable.

6. A high-frequency coil device according to claim 1, A high-frequency coil device characterized by being a coil for head examination.

7. A high-frequency coil device according to claim 1, The second coil unit is movable on a circular track, and the first coil unit is fixed within the circular track. A high-frequency coil device characterized in that the conductor loop of the first coil unit and the conductor loop of the second coil unit adjacent thereto are arranged in such a positional relationship that the distance between the centers of each conductor loop is substantially constant in at least a portion of the movable range of the second coil unit.

8. A high-frequency coil device according to claim 7, A high-frequency coil device in which the second coil unit moving along the circular track has a range of motion of 10 degrees or more and 90 degrees or less.

9. A high-frequency coil device according to claim 7, The high-frequency coil device is characterized in that the second coil unit is arranged such that the center of the circular trajectory is located inside the conductor loop that is closest to the first coil unit.

10. A magnetic resonance imaging apparatus comprising an RF transmitting coil for applying a high-frequency magnetic field to a subject and an RF receiving coil for detecting a nuclear magnetic resonance signal from the subject, wherein at least one of the RF transmitting coil and the RF receiving coil is the high-frequency coil apparatus described in claim 1.

11. A magnetic resonance imaging apparatus according to claim 10, A magnetic resonance imaging apparatus comprising a dual-purpose RF coil that serves as both an RF transmitting coil and an RF receiving coil, wherein the dual-purpose RF coil is the high-frequency coil device described in claim 1.

12. A magnetic resonance imaging apparatus according to claim 10, A magnetic resonance imaging apparatus characterized in that the RF receiving coil is a receiving coil for head examination and is a high-frequency coil device as described in claim 1.

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