JP7293098B2 - MRI equipment and RF coil unit for MRI equipment - Google Patents

Description

The embodiments disclosed in the specification and drawings relate to an MRI apparatus and an RF coil unit for an MRI apparatus.

Magnetic Resonance Imaging (MRI) involves exciting the nuclear spins of a subject's tissue in a static magnetic field with an RF (radio frequency) pulse having its Larmor frequency and generating magnetic resonance signals (MR signals) based on this excitation. It is an imaging method that reconstructs image data using

An MRI apparatus (magnetic resonance imaging apparatus) is an imaging diagnostic apparatus that generates image data based on MR signals detected from within a living body. The ability to obtain information is essential in the current field of diagnostic imaging.

In order to generate good quality image data with an MRI apparatus, it is important to detect weak MR signals from a living body with high sensitivity. To that end, many technical improvements have been made to RF coils that detect MR signals. The RF coils provided in the MRI apparatus are composed of a transmitting RF coil that emits RF pulses to excite a diagnosis target region of a subject and a receiving RF coil that detects MR signals from the subject. However, since the excitation timing and the MR signal detection timing are different, it is also possible to use the same RF coil for RF pulse irradiation and MR signal detection.

In order to efficiently detect the above-mentioned MR signals, it is desirable to place the RF coil close to the diagnosis target region of the subject. For this reason, a dedicated RF coil has been developed that matches the shape of the diagnostic target site. For example, in MRI imaging of the upper abdomen such as the liver, the RF coil is used as a pair of an upper RF coil above the subject and a lower RF coil below the subject so that the subject is positioned between them. Since it is difficult to move the lower RF coil located below after the subject is placed on the tabletop, it is usually placed over a wide range on the back side of the subject, and the upper RF coil is positioned within the range of the diagnostic target area. Together, they are placed on the subject.

At this time, in order to prevent the upper RF coil from moving during imaging by the MRI apparatus, the operator placed the upper RF coil at an appropriate position on the subject before imaging and connected it to the top plate. It was necessary to fix the subject and the upper RF coil using a band, and this work was a burden on the operator and the subject, and reduced the efficiency of MRI imaging.

JP-A-10-57335 U.S. Pat. No. 9,506,455

One of the problems to be solved by the embodiments disclosed in the specification and drawings is to improve the efficiency of MRI imaging. However, the problems to be solved by the embodiments disclosed in this specification and drawings are not limited to the above problems. A problem corresponding to each effect of each configuration shown in the embodiments described later can be positioned as another problem.

An RF coil unit for an MRI apparatus according to an embodiment includes an upper RF coil, an upper RF coil holder, and an RF coil support. An upper RF coil is positioned above the subject and provides detection of MR signals. The upper RF coil holding section holds the upper RF coil and has an air pressure chamber inside, and the upper RF coil moves toward the subject by applying air pressure to the air pressure chamber. The RF coil supporting section supports the upper RF coil holding section above a top plate on which the subject is placed.

FIG. 1 is a schematic diagram showing the overall configuration of the MRI apparatus according to this embodiment. FIG. 2 is a view showing the XY cross section of the RF coil unit according to the present embodiment before the upper RF coil holding section is driven. FIG. 3 is a view showing the XY section after driving the upper RF coil holding portion of the RF coil unit according to the present embodiment. FIG. 4 is a diagram for explaining the movement of the RF coil unit on the top plate according to this embodiment.

Hereinafter, embodiments of an MRI apparatus and an RF coil unit for an MRI apparatus will be described in detail with reference to the drawings. In addition, embodiment is not restricted to the following embodiments.

The configuration of the MRI apparatus according to this embodiment will be described with reference to FIGS. 1 to 4. FIG. FIG. 1 is a schematic diagram showing the overall configuration of the MRI apparatus according to this embodiment. FIG. 2 is a view showing the XY cross section of the RF coil unit according to the present embodiment before the upper RF coil holding section is driven. FIG. 3 is a view showing the XY section after driving the upper RF coil holding portion of the RF coil unit according to the present embodiment. FIG. 4 is a diagram for explaining the movement of the RF coil unit on the top plate according to this embodiment.

As shown in FIG. 1, the MRI apparatus 100 includes a static magnetic field generator 1 and a gradient magnetic field generator 2 that generate a magnetic field for a subject 150, and an RF pulse irradiation and an MR signal reception for the subject 150. a table 4 on which the subject 150 is placed, and a table moving mechanism 5 for moving the table 4 in the body axis direction of the subject 150 (long axis direction of the table 4). Equipped with

The MRI apparatus 100 includes an image data generating unit 6 that reconstructs the MR signals received by the transmitting/receiving unit 3 to generate image data, a display unit 7 that displays the generated image data, MR signal acquisition conditions and An input unit 8 for setting image data display conditions, inputting various command signals, etc., and a control unit 9 for controlling each unit in the MRI apparatus 100 are provided.

The static magnetic field generator 1 has a main magnet 11 composed of a normal conducting magnet, a superconducting magnet, or the like, and forms a strong static magnetic field with respect to a subject 150 placed in the imaging field of a gantry (not shown). Note that the main magnet 11 may be composed of a permanent magnet.

The gradient magnetic field generator 2 includes gradient magnetic field coils (Gx, Gy, Gz) 21 that form gradient magnetic fields in the X-axis direction, the Y-axis direction, and the Z-axis direction, which are orthogonal to each other, and each Gx of the gradient magnetic field coil 21, A gradient magnetic field power supply 22 for supplying pulse currents to Gy and Gz is provided.

The gradient magnetic field power supply 22 encodes the imaging field in which the subject 150 is placed based on the sequence control signal supplied from the control unit 9 . That is, the gradient magnetic field power supply 22 controls the pulse currents supplied to the gradient magnetic field coils 21 in the X-axis direction, the Y-axis direction, and the Z-axis direction based on the sequence control signal, thereby generating a gradient magnetic field in each direction. Form. Then, the gradient magnetic fields in the X-axis direction, the Y-axis direction, and the Z-axis direction are combined to form a slice selection gradient magnetic field (Gs), a phase-encoding gradient magnetic field (Ge), and a frequency-encoding gradient magnetic field (Gr) orthogonal to each other in desired directions. , and these gradient magnetic fields are superimposed on the static magnetic field formed by the main magnet 11 and applied to the subject 150 .

The transmitting/receiving unit 3 includes an RF coil unit 31 having an RF coil for irradiating the subject 150 with an RF pulse and detecting an MR signal from the subject 150, and a transmission unit 31 for supplying an RF signal to the RF coil. 32 and a receiver 33 that performs predetermined processing on the MR signal detected by the RF coil.

The RF coil unit 31 is positioned above the subject 150 and irradiates the subject 150 with RF pulses and detects MR signals. An upper RF coil holding portion 312 that holds from the inside and has an air pressure chamber that bends when air pressure is applied to the air pressure chamber, and an upper RF coil that applies air pressure to the air pressure chamber of the upper RF coil holding portion 312. The holding part driving mechanism part 330 is supported on the top plate 4 on which the subject 150 is placed so as to be movable in the longitudinal direction of the top plate 4, and the upper RF coil holding part driving mechanism part 330 and the upper RF coil holding unit An RF coil support portion 314 is provided to support the portion 312 from above.

As the upper RF coil holding part 312, for example, as disclosed in US Pat. No. 9,506,455, it is made of silicone rubber having an air pressure chamber therein, and is bent by applying air pressure to the air pressure chamber. structure can be applied. Then, as shown in FIG. 3, the arrangement is such that it bends toward the subject 150 when air pressure is applied, and the distal end portion of the upper RF coil holding section 312 protruding toward the subject 150 due to the bending is moved from above (upper portion). The upper RF coil holding part 312 detachably holds the upper RF coil 311 by detachably connecting it to the upper RF coil 311 (on the subject 150 side as viewed from the RF coil holding part 312). In addition, since the overall distance in the bending direction does not change when air pressure is applied to the upper RF coil holding part 312, the distance between the tip parts when the air pressure is applied to the upper RF coil holding part 312 to bend is less than the distance between the tips before air pressure is applied. Therefore, each tip portion is connected to the upper RF coil 311 so as to be movable (slidable) in the bending direction at the connection point of the upper RF coil 311 (that is, the upper RF coil holding portion 312 is connected to the upper RF coil 311). movable along the articulating plane).

The upper RF coil holding part 312 bends to move the held upper RF coil 311 toward the subject 150 (that is, bring the upper RF coil 311 closer to the subject 150). In order to efficiently detect MR signals, it is desirable that the upper RF coil 311 be brought closer to the diagnosis target region of the subject 150 . For this reason, the degree of curvature of the upper RF coil holding part 312 is preferably such that the upper RF coil 311 to be held is kept in light contact with the subject 150 or slightly separated from the subject 150 during MRI imaging. The degree of curvature can be adjusted by adjusting the degree of air pressure applied. Since the upper RF coil holding part 312 is made of silicone rubber, even when the upper RF coil 311 contacts the subject 150, it is in soft contact with the subject 150. Therefore, the impact given to the subject 150 is reduced. extremely small.

Some of the upper RF coils 311 have an area that covers the body surface of the subject 150, and the upper RF coil 311 with such a wide area is stably moved toward the subject 150 by the bending operation of the upper RF coil holder 312. In order to move, it is preferable to have a configuration in which one upper RF coil 311 is held by a plurality of upper RF coil holding portions 312 . A single RF coil 311 is held by a plurality of upper RF coil holders 312 .

The top plate 4 has a guide groove 41 along the longitudinal direction of the top plate 4 , and the RF coil unit 31 has an RF coil unit moving mechanism 331 that moves the RF coil support portion 314 along the guide groove 41 . equip.

By providing the mechanism as described above, as shown in FIG. The upper RF coil holding portion 312 in a steady state (a state in which air pressure is not applied and is not curved) supported from above via the RF coil support portion 314 while the end portion of the portion 314 is supported by the guide groove 41 . After mounting the appropriate upper RF coil 311 on the diagnostic part of the subject for MRI imaging, the RF coil unit moving mechanism part 331 is driven by the operator's instruction operation, and the RF coil support part 314 is moved along the guide groove 41. After moving the RF coil 311 to a position above the subject 150 in order to place the RF coil 311 at an appropriate position for MRI imaging, the upper RF coil holding portion drive mechanism 330 is moved by the operator's instruction operation. By driving, the application of air pressure to the upper RF coil holding part 312 continues to bend, and the held upper RF coil 311 is moved toward the subject 150 . When the upper RF coil 311 approaches or contacts the subject 150 to an appropriate position, the operator stops instructing the upper RF coil holding part drive mechanism part 330 and moves the upper RF coil holding part 312. The continuous application of air pressure is stopped to stop the movement of the upper RF coil 311, the movement of the upper RF coil 311 is locked while the position is maintained, and MRI imaging is started in this state.

After the MRI imaging is completed, the operator issues an instruction to the upper RF coil holding unit drive mechanism unit 330 to unlock the upper RF coil 311 and hold it inside the upper RF coil holding unit 312. release the air pressure. Due to the release of the internal air pressure, the upper RF coil holding portion 312 recovers from the curved state to the original steady state. By restoring the upper RF coil holding part 312 to a steady state, the upper RF coil 311 moves away from the subject 150 and moves from the original upper RF coil holding position to the position close to or in contact with the subject 150 . It returns to the position attached to the portion 312 .

After the upper RF coil 311 is separated from the subject 150, the operator drives the RF coil unit moving mechanism 331 to move the RF coil support 314 along the guide groove 41, thereby moving the RF coil 311 to MRI. In order to retreat from the imaging position, it moves to a position where it does not cover the subject 150 (for example, the feet of the subject 150). After the RF coil support section 314 is retracted to a position where the subject 150 is not covered by the subject 150, the top board 4 is moved to the home position in order to remove the subject 150 placed on the top board 4 from the top board 4. , and the subject 150 is lowered from the top plate 4 .

According to the above-described embodiment, the upper RF coil holding portion 312 supported from above by the RF coil support portion 314 supported on the top plate 4 holds the upper RF coil 311 from above and also holds the upper RF coil 311 from above. It has a pneumatic chamber, and when pneumatic pressure is applied to the pneumatic chamber, it bends toward the subject 150 , and by bending, the holding upper RF coil 311 moves toward and approaches the subject 150 . Thus, the work of fixing the upper RF coil 311 on the subject 150 with a belt can be omitted, the load on the operator and the subject can be reduced, and the efficiency of MRI imaging can be improved.

Also, the position of the upper RF coil 311 of this embodiment is not limited to the above description. The upper RF coil 311 may be positioned vertically above the subject 150 (as shown in FIG. 2) or horizontally (height) above the subject 150 (not shown). ). The vertical direction of the subject 150 is the direction of the connection line between the subject 150 and the ground after the subject 150 is laid on the top board 4, that is, the Y-axis direction shown in FIG. The horizontal direction of the subject 150 is the penetrating direction of the head and feet of the subject 150, that is, the Z-axis direction shown in FIG.

Furthermore, although the RF coil support section 314 of the present embodiment has been described as being supported on the top plate 4, it may be supported by a bed device that supports the top plate 4, for example. In that case, the guide groove 41 is provided not on the top plate 4 but on the bed device.

According to the embodiments described above, the efficiency of MRI imaging can be improved.

While embodiments of the invention have been described, the embodiments have been presented by way of example and are not intended to limit the scope of the invention. This embodiment can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. This embodiment and its modifications are included in the scope and gist of the invention, as well as the scope of the invention described in the claims and its equivalents.

31 RF coil unit 311 Upper RF coil 312 Upper RF coil holder 314 RF coil supporter 330 Upper RF coil holder drive mechanism

Claims (9)

an upper RF coil positioned above the subject for detecting MR signals;
An upper RF that holds the upper RF coil, has an air pressure chamber inside, bends itself by applying air pressure to the air pressure chamber, and moves the upper RF coil in the direction of the subject a coil holder;
an RF coil supporting part that supports the upper RF coil holding part above the top plate on which the subject is placed;
An RF coil unit for an MRI apparatus. The upper RF coil holding part bends itself while a portion in contact with the upper RF coil moves along a connection surface with the upper RF coil by applying air pressure to the air pressure chamber. and moving the upper RF coil in the direction of the subject;
An RF coil unit for an MRI apparatus according to claim 1. Further comprising an upper RF coil holding unit drive mechanism that applies air pressure to the air pressure chamber,
An RF coil unit for an MRI apparatus according to claim 1. The upper RF coil is positioned vertically above the subject,
An RF coil unit for an MRI apparatus according to claim 1. The upper RF coil holding part is made of silicon rubber,
An RF coil unit for an MRI apparatus according to claim 1. The RF coil support can move along the longitudinal direction of the top plate.
An RF coil unit for an MRI apparatus according to claim 1. A plurality of the upper RF coil holding parts are arranged along the RF coil support part, and one of the upper RF coils is held by the plurality of upper RF coil holding parts,
An RF coil unit for an MRI apparatus according to claim 1. The top plate has a guide groove along the longitudinal direction of the top plate,
The RF coil unit includes an RF coil unit moving mechanism that moves the RF coil support along the guide groove,
The RF coil unit for an MRI apparatus according to claim 5. In an MRI apparatus that generates an MR image by detecting MR signals generated by irradiating a subject with RF pulses,
an upper RF coil positioned above the subject for detecting the MR signal;
It holds the upper RF coil from above, has an air pressure chamber inside, and bends itself when air pressure is applied to the air pressure chamber, thereby moving the upper RF coil in the direction of the subject. an upper RF coil holder;
an RF coil supporting part that supports the upper RF coil holding part above the top plate on which the subject is placed;
MRI apparatus with

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